2023
SCIENTIFIC
REPORT
2023
SCIENTIFIC
REPORT
© Chr. Morel / CEA
SCIENTIFIC
REPORT
2023
T
The year 2023 was marked by the arrival—amid much
hype—of generative AI on the consumer and industrial
markets. This new technology could affect not only our
electronic component development roadmaps, but also
our work itself. Climate change was also top of mind
as temperatures hit record highs around the globe.
Against this rapidly-changing backdrop, the industrial and
technology sectors are now unequivocally faced with some
sizeable challenges that raise essential questions about the
role of digital—as both a cause and a potential cure. It is up
to us, at least in part, to decide what we will make of it.
he publication of our Scientific
Report is a personal highlight for me
each year. And, while it is difficult
to compare our results from one
year to the next, 2023 stands out in several
ways. First, the number of CEA-Leti papers
and presentations in international journals
and at international scientific conferences
grew significantly, generating an impressive
number of awards for our scientists from
PhD student to senior. The global scientific
community’s recognition of the pertinence
of our research reaffirms our position as a
major research and technology stakeholder
in a field where the already-brisk pace of
innovation is accelerating: digital.
At the CEA our ambition is to put our
facilities and brain power to work on the
challenges ahead. And CEA-Leti’s roadmap
now addresses the environmental and
societal issues around the development
of technology, with further convergence
planned for the coming years. Our long
tradition of R&D on very-low-power
technologies and on substrates that make
more economical use of materials is 100%
aligned with today’s context.
Our R&D partners turn to us for help with
their technology-related problems. That
hasn’t changed. What has changed, however,
is that they are now coming to us for broader
business solutions—solutions that are also
more responsible and ethical. The winds have
shifted, and our people are more motivated
and inspired than ever to make an impact.
Sébastien Dauvé
CEO, CEA-Leti
4
© UtopikPhoto / CEA
The electronics industry is zeroing in on low-power
solutions, and Chips Acts in Europe, the United
States, and Asia opened up exciting new research
and development opportunities in 2023. Throughout
the year, CEA-Leti worked closely with partners
from diverse horizons to bring new low-power
technologies to the market.
T
his year’s Scientific Report reflects
the broad scope of our research.
In addition to our historic focus
areas—energy-efficient computing,
sensors (including biosensors) and displays,
materials and integration—our crossdisciplinary research and development
targeting specific industries and use
cases also generated some noteworthy
breakthroughs.
We made exciting developments in
technologies for Edge AI, quantum
computing, telecommunications, and 3D
integration. Our health program, with
advances in organs-on-chips, echoed the
more general trend toward digital-enabled
medicine that is driving demand for
increased miniaturization.
Our organization-wide eco-innovation
program also continued to grow, with
projects addressing the impacts of
our R&D activities and of the resulting
technologies. Our R&D partners are
showing increasing interest in technologies
backed by lifecycle analyses and other
eco-innovation approaches.
Many of the results in the following pages
are the fruit of joint research with our
partners, be they academic research labs
or companies. I would like to thank them
for their continued trust in us. I would
also like to extend my gratitude to our
people at CEA-Leti for their extraordinary
commitment and dedication. I am thrilled
to share this year’s Scientific Report with
you, and I hope you enjoy it.
Thomas Ernst
VP Science and Technology,
CEA-Leti
5
SCIENTIFIC
REPORT
2023
CEA-LETI AND THE CARNOT NETWORK
08
CONTENT
SUSTAINAIBLE DEVELOPMENT10
MATERIALS AND DEVICES
FOR ENERGY EFFICIENT COMPUTING
PUSHING COMPUTING AND MEMORY TO THE EDGE FOR
INCREASED ENERGY EFFICIENCY IN THE ERA OF IOT
Elisa Vianello, Gabriele Navarro, Tifenn Hirtzlin, with Souifi Abdelkader (INSA) 14
ADVANCES IN QUANTUM HARDWARE
Biel Martinez, Jean-Michel Hartmann, Ségolène Olivier,
with Gérard Ghibaudo (IMEP-LAHC)18
World first: nanoscale electrostatic
potential mapping in active micro-LEDs
David Cooper24
3D integration: pulsed-laser annealing for
accurate control of silicon recrystallization
Sébastien Kerdilès
25
Market news from our R&D partners26
SMART POWER DEVICES
CEA-Leti presents advances in transferred SiC substrates
for electronics and photonics at ICSCRM 2023
Julie Widiez30
Insulated recessed gate GaN power transistors
enable promising normally-OFF architecture
Pedro Fernandes Paes Pinto Rocha32
New model for the optimization of
high-energy-density microbatteries for IoT devices
Sami Oukassi34
Piezoelectric materials could enable more
compact, efficient power converters
Ghislain Despesse
36
Market news from our R&D partners38
IMAGING, DISPLAYS AND SENSORS FOR SMART HUMAN
ENVIRONMENT & MACHINE INTERACTION
Semiconductor development to benefit from
GPU-accelerated CZT detector simulation
Guillaume Montémont44
ADVANCES IN INFRARED IMAGING
Sebastien Becker, Jacques Baylet, Olivier Gravrand
46
New analysis capabilities could help make future
infrared detectors more robust
Nicolas Baier48
Meta-optics for inertial confinement fusion laser facilities
Pierre Brianceau, Jérôme Neauport, Nicolas Bonod
50
Algorithm-architecture co-design for compact
representation of ToF pixel data
William Guicquero
52
Market news from our R&D partners54
6
TELECOMUNICATION AND SECURITY FOR CONNECTED SOCIETY
THE 5G TO 6G TIPPING POINT HAS ARRIVED
Jean-Baptiste Doré, Erwan Morvan, Luc Maret, Mohamed Sana,
with Alexis Fischer (Université Sorbonne Paris Nord)
58
Smart antennas: manipulating, shaping, and controlling
electromagnetic waves for telecommunications,
localization, and sensing
Christophe Delaveaud62
Ultra-low-power filter for RF spectrum sensing could lead
to more energyefficient “listening” on IoT networks
Dominique Morche
64
Record mmW radar performance to support
remote contactless vital sign detection
Mykhailo Zarudniev65
AI-enabled power amplification could help make
wireless communications more energy efficient
Jean-Baptiste Doré66
Pulsed-laser deposition of lithium niobate thin films
for applications ranging from 5G to quantum
Florian Dupont67
Evaluating the robustness of embedded neural network
models for more secure Edge AI in a physical world
Pierre-Alain Moellic68
Market news from our R&D partners
70
GENERIC MATERIALS
AND CHARACTERIZATION
ADVANCED PACKAGING
Jean Charbonnier, Emilie Bourjot, Jean-Charles Souriau,
Thierry Mourier 74
CEA-Leti and Intel join forces on novel self-assembly
technology that could enable high-throughput
die-to-wafer bonding
Frank Fournel78
Lab-scale hard X-ray photoelectron spectroscopy
(lab-HAXPES) for MOSc-HEMT characterization
Eugénie Martinez80
TMD-like semiconducting materials grown at
BEOL-compatible temperatures
Stéphane Cadot82
Making cleanrooms cleaner with ecofriendly chitosan
water-based lithography resists for sustainable nanofabrication
Isabelle Servin
83
EMERGING DEVICES TO IMPROVE HUMAN HEALTH
ADVANCED SENSING AND STIMULATION TECHNOLOGIES
DRIVE INNOVATIONS IN PATIENT MONITORING,
TREATMENT, AND MOBILITY
Abdelmadjid Hihi, Christelle Godin, Salam Hamieh, Emma Villeneuve,
Guillaume Charvet, with Dr Hussein Al Osman (u Ottawa)
and Henri Lorach (EPFL)86
ORGANS-ON-CHIPS SUPPORT SAFER,
MORE PERSONALIZED MEDICINE
Fabrice Navarro, Frédéric Bottausci, Pascal Mailley 90
Toward biocompatible printed electronics for transient,
bioresorbable medical devices
Isabelle Texier92
3D time-lapse imaging could bring advanced
pre-implantation embryo observation to IVF clinics
Lionel Hervé93
New rapid bloodstream pathogen identification technique
for faster diagnosis of infections
Pierre Marcoux94
Unprecedented phage surface density could help advance
phage therapy and enable new antibacterial surfaces
Pierre Marcoux, Larry O’Connell95
New technique detects lethargic but still-infectious
pathogens for safer seafood
Pierre Marcoux96
Cancer screening and environmental microplastics
detection could benefit from a label-free MIR
interferometric imaging technique
Marine Beurrier-Bousquet
97
Market news from our R&D partners
98
AWARDS
104
7
SCIENTIFIC
REPORT
2023
Committed to innovation,
CEA-Leti creates differentiating
solutions with its partners
CEA-Leti, a technology
research institute at CEA, is a
global leader in miniaturization
technologies enabling
smart, energy-efficient and
secure solutions for industry.
Founded in 1967, CEA-Leti pioneers micro-&
nanotechnologies, tailoring differentiating
applicative solutions for global companies, SMEs
and startups. CEA-Leti tackles critical challenges
in healthcare, energy and digital migration.
From sensors to data processing and computing
solutions, CEA-Leti’s multidisciplinary teams
deliver solid expertise, leveraging world-class
pre-industrialization facilities. With a staff of more
than 2,000 talents, a portfolio of 3,200 patents,
11,000 sq. meters of cleanroom space and a
clear IP policy, the institute is based in Grenoble,
France, and has offices in Silicon Valley, Brussels
600
Founded in
IS0 9001
Based in
publications per year
certified since 2000
114
European projects
and Tokyo. CEA-Leti has launched 76 startups
and is a member of the Carnot Institutes network.
Technological expertise
CEA has a key role in transferring scientific
knowledge and innovation from research to
industry. This high-level technological research
is carried out in particular in electronic and
integrated systems, from microscale to
nanoscale. It has a wide range of industrial
applications in the fields of transport, health,
safety and telecommunications, contributing
to the creation of high-quality and competitive
products.
Follow us on
cea-leti.com
@CEA-Leti
1967
France (Grenoble)
with offices in the
US (San Francisco) and
Japan (Tokyo)
Belgium
(Brussells)
300
industrial partners
2,000
researchers
3,200 patents
in portfolio
11,000
sq. meters of cleanrooms
100-200-300 mm wafers
76
© CEA
startups created
8
Susana Bonnetier
VP of the Carnot Network and
Carnot Program Manager
Scientific Directorate of CEA-Leti
CEA-Leti is a member of the French Carnot network:
39 institutes dedicated to the co-development of
differentiating technologies with and for businesses
worldwide to support industrial development and
competitiveness. The Carnot institutes represent 20% of
the French public research force (35,000 professionals
dedicated to generating innovation for industry) and sign
a hefty 11,000 direct contracts yearly with companies
in all economic sectors, be it start-ups, SMEs or large
groups, helping to bring new products to the market
for the benefit of society. The Carnot institutes have
the additional capacity of working together to respond
with comprehensive and interdisciplinary solutions to
the major R&D challenges faced by industry today. It
comes as no surprise, then, that over 50% of all the R&D
contracts signed between French industry and French
public research organisms involve a Carnot institute.
Some remarquable results produced
by Carnot projects in 2023 include:
•
•
•
•
•
In 2023, Carnot projects opened new venues of
research in areas such as, for example, eco-innovation,
high performance computing, advanced CMOS
architectures, 5 and 6G enabling technologies, classic
and quantum photonics, cyber-physical systems
and cybersecurity, power electronics and energy
management systems, medical devices, connected
health and personalized medicine. Many of these
projects benefitted from collaborations with national
and international academic partners that help
strengthen our scientific excellence and professionalism,
while reinforcing our open mindset and sharpening our
vision of the future.
•
•
Improved photoluminescence of annealed samples
was observed for patterned GeSn epitaxial
microstructures, for annealing temperatures above
epitaxial growth temperature, this will be particularly
useful for optically pumped lasers;
The wavefront of a defocused laser beam was
successfully shaped to focus light on a target, using a
scalable and compact integrated phase modulator that
combines a Liquid Crystal Cell with a CMOS image
sensor;
New mmWave and THz RF components were
developed using 3D integrated photonics on CMOS ;
Cathodoluminescence and Kelvin Force microscopy
were successfully combined to analyze LEDs sidewall
defects ;
A brain computer interface developed at CEA-Leti,
combined with a spine stimulator developed at EPFL,
enabled thought-controlled walking after a spinal
cord injury;
The first injection-locked oscillator-based time-domain
feature extraction for KWS (keyword spotting) operating
at 0.4V supply voltage was achieved, with a 91% accuracy
on 10 words;
Spintronic memories for emerging computational
concepts were developed using various hybrid
CMOS+MTJ building blocks.
MQW : multiple quantum wells ;
RT : room temperature
© CEA
The French Ministry of Higher Education and Research
created the Carnot label in 2006 to recognize public R&D
institutes that successfully transfer the results of their
research to industry. To obtain the Carnot label, institutes
must actively cultivate both their scientific excellence and
their professionalism when engaging in R&D partnerships
with businesses. The label comes with government
funding aimed at preparing the next round of disruptive
technologies for industry. CEA-Leti uses these funds
to finance a bi-yearly call for proposals that stimulates
the upsurge of new ideas from researchers and to carry
out multidisciplinary top-down projects that generate
demonstrators aimed at maturing technological concepts
into tangible and transferable results.
© P. Jayet / CEA
The French “Carnot” institutes
are the preferred R&D partners
of France’s innovative companies
“Cathodoluminescence (CL) and KPFM images showing analysis
at the edge of a 1 mm2 GaN mesa. CL results reveal reduced
intensities related to InGaN quantum well emission, KPFM
measurements indicating charge trapping of holes in the surface of
p-GaN, as evidenced by the positive surface photovoltage (SPV).“
Find out more about the Carnot institutes by clicking
www.instituts-carnot.eu
9
SCIENTIFIC
REPORT
2023
CEA-Leti voices
on eco-innovation
Léa, you created CEA-Leti’s
eco-innovation program in 2020,
and you passed the torch to your
successor, Laurent Pain, this year.
What motivated you to take on this
ambitious project back in 2019?
© Rangizzz - Fotolia.com
LD: Once you start thinking about
climate
change and understanding
Léa Di Cioccio
its
implications,
you can’t help but
Eco-innovation
Program Director,
want to get others on board. As a
CEA-Leti
leading center for semiconductor
research and development, I feel it is our responsibility
to initiate this important transformation by integrating
ecodesign and lifecycle assessment methods into our
technologies to reduce the impacts of the semiconductor
industry on climate change and on our planet’s finite
resources. We must also take steps to use less water
and limit the impacts of the pollutants generated by our
activities and technologies on the air and soil. That’s
what I’ve been working on for the past three years at
CEA-Leti—a mission that I am sure Laurent will carry
on with brio moving forward. I will continue to serve
in an advisory role as a CEA Fellow and I plan to keep
eco-innovation at the center of my activities.
10
© B. Lavit / CEA
© Christian Morel / CEA
It is now widely accepted that the “take, make, use, dispose” model of production
and consumption is no longer viable. This is especially true for the semiconductor
industry. As the number of electronic devices in operation worldwide continues
to grow exponentially, all aspects of the semiconductor product lifecycle must be
addressed urgently to reduce environmental impacts. This includes the products
themselves, of course, but also processes at all stages from R&D to manufacturing
and recycling. CEA-Leti Eco-Innovation Program Managers Léa DiCioccio and Laurent
Pain talked to us about the organization’s efforts to make not only its own cleanroom
processes, but also the technologies it transfers to partners, more sustainable.
Laurent, what is your main driver
as you take on this new role?
LP: Integrated circuit technology
offers the potential to help address
some of our climate-related
challenges. Yet, at the same time,
as the number of devices in use
Laurent Pain
increases, so do the impacts.
CEA-Leti research
Within this paradox is, of course,
director
the challenge of reducing those
impacts, but also opportunities to continue to bring
sustainable innovations to society. That’s what I’m
interested in. When Léa started the project, she took
a holistic approach, addressing both environmental
and societal impacts, and successfully raising CEA-Leti
management’s awareness of what is at stake. Some
of the foundational activities Léa got up and running
are collecting data from our clean rooms so we can
systematically conduct lifecycle analyses and running
in-house eco-innovation workshops with our staff. I plan
to continue to build on that solid foundation.
“Making semiconductors more sustainable
is both a sprint and a marathon. We have to
act now and maintain our efforts over the
long term. The Eco-innovation Program is our
instrument for doing just that, both within
CEA-Leti and with our external R&D partners.”
Laurent Pain
So, eco-innovation has clearly started to take hold across
CEA-Leti and with its R&D partners since the program
was launched. But the wider environment has also
changed. How will this impact the industry in terms of
sustainability?
LD: The European Green deal and pressure from the
general public are pushing companies in all industries to
use less energy and be more sustainable. As Laurent said,
semiconductors can be part of the
solution in many industries, but
they also have their own impacts.
The Chips Acts will accelerate
the uptake of more sustainable
manufacturing practices in our
industry, but there is still work to be
done on the product use end.
LP: The main purpose of the Chips
Acts, whether it’s in Europe, the
United States, or Japan, is to
support R&D, but the Acts all have
sustainability components. This will
create space for new conversations
that, I hope, will move us, together
as an industry, in the right direction.
Where would you like to see the semiconductor industry
in five to ten years in terms of sustainability?
LP: Manufacturing has the potential to drive significant
progress on our environmental performance. We are
talking about precision manufacturing down to the
nanometer. A whopping 90% to 99% of the material
used is discarded. Even if the part we do use is used
in extraordinary ways, I would like to see more circular
manufacturing that would allow us to recover material
and reuse it in our fabrication processes. Then there is
the issue of repairability. I hope that one day we will have
more repairable components, where the package can
be reused and only the faulty subcomponent repaired or
replaced. This could happen through more applicationspecific components.
LD: This is exactly the kind of solution our R&D partners
are looking for, and no one is better placed to deliver it
than CEA-Leti.
Further reading
• Vauche, L., Guillemaud, G., Lopes Barbosa, J.-C., & Di Cioccio,
L. (2024). Cradle-to-Gate Life Cycle Assessment (LCA) of GaN
Power Semiconductor Device. Sustainability, 16(2), 901.
• Guillemaud, G., Vauche, L., Lopes Barbosa, J. C., Sousa, V.,
& Di Cioccio, L. (2023, July). Empreinte environnementale d’un
composant de puissance à base de GaN. Paper presented at
the Symposium de Génie Électrique (SGE), Lille, France.
© Shuo / AdobeStock
LD: Management is 100% on board now, and in 2023 we
saw two new firsts: the launch of our eco-innovation services
to outside R&D partners and the completion of a carbon
audit of our activities. Our Sustainable Electronics program is
now well-established, and the methods developed are being
integrated into more and more of our R&D projects. Our
R&D partner companies are thrilled to see us responding to
this need, so that they in turn can bring relevant solutions
to their markets. In power electronics, we also made a
notable advance in eco-innovation in 2023, assessing the
environmental impacts of a GaN power component (see
“Further reading” below).
11
© xiaoliangge - Adobe Stock
SCIENTIFIC
REPORT
2023
12
01 I MATERIALS AND DEVICES FOR ENERGY EFFICIENT COMPUTING
MATERIALS AND DEVICES
FOR ENERGY EFFICIENT
COMPUTING
Jean-Paul Barnes
© Utopikphoto / CEA
Scientific Advisor to
the Technology Platform Division
CEA-Leti is innovating in materials,
processes, and integration to drive
progress in advanced computing
and photonics applications. In 2023
we made strides in chalcogenide
materials and leveraged synergies
between filamentary and ferroelectric
memories for Edge AI. Our quantum
computing research hit milestones
in isotopically enriched silicon
heterostructures, low-temperature
transistor modeling, and photonic
quantum circuits. Finally, our
expertise in nanocharacterization
techniques allowed us to improve
electrostatic mapping for the
exploration of advanced LED
structures.
13
SCIENTIFIC
REPORT
2023
PUSHING COMPUTING AND
MEMORY TO THE EDGE FOR
INCREASED ENERGY EFFICIENCY
IN THE ERA OF IOT
As the digital fabric of our society becomes increasingly dense, the capacity of Edge
computing solutions to efficiently process and analyze data near or at the sensor will have
a profound impact on power consumption, of course, but also on system performance.
CEA-Leti and its partners continued to drive advances in this exciting field in 2023,
leveraging expertise from materials to characterization to integration.
CEA-Leti labs are addressing the growing non-volatile
memory market with innovations in materials crucial to
keeping up with future demand. This included a deep
dive into the switching and failure phenomena at work in
memory and selector devices made from chalcogenides.
This research will help increase memory density, which in
turn will enable new Edge AI solutions in the future.
© UtopikPhoto / CEA
While progress continues on this novel selector device,
we pursued our investigations of a more mature approach
exploiting a CMOS transistor as a selector to create a
groundbreaking Bayesian machine, marking a significant
step forward in energy-efficient Edge artificial intelligence.
By addressing AI’s energy consumption
issues and offering an explainable
alternative to conventional “black box”
neural networks, the novel device could
enable transformative Edge AI use
cases. “A decade-long collaboration
with Dr. Damien Querlioz, CNRS
Researcher at C2N, the Centre for
Nanoscience
and Nanotechnology,
Elisa Vianello
14
Nanoelectronics Department, Université Paris-Saclay,
has been instrumental in allowing us to test new
computing paradigms. This partnership has now
expanded through the PEPR Electronique and Neuronic
projects, both financed in part by France’s national
research agency, and through two jointly-supervised
PhD students, one of whom, Tifenn Hirtzlin, is now on
staff at CEA-Leti,” said CEA-Leti’s Elisa Vianello.
In other Edge AI research, with Dr. Querlioz’s team and
CEA-List, we looked at the integration of resistive and
ferroelectric memories, opening up new avenues for
neuromorphic computing. This novel co-integration,
presented at IEDM 2023, is a breakthrough for on-chip
learning and inference, crucial for the continuous, real-time
processing required by next-generation IoT applications.
Pivotal research with laboratories at INSA Lyon
establishes link between chalcogenide structure
and OTS device behavior
CEA-Leti worked with labs at INSA Lyon on
groundbreaking research leveraging physico-chemical and
© INSA
© itchaznong - Adobe Stock
01 I MATERIALS AND DEVICES FOR ENERGY EFFICIENT COMPUTING
According to Navarro, “Co-supervising PhD students
definitely got us talking more often than we would
have otherwise. I can’t help but feel this has had a
positive impact on our research.”
© CEA
electrical characterization analysis. For example, Raman
spectroscopy was used to study the structure of an OTS
material integrated into selector devices with a transparent,
conductive indium tin oxide layer for the top electrode,
analyzing the devices after multiple switching operations.
Raman spectra were acquired after up to 1,000 switching
cycles to highlight the structural changes in the region
involved in the switching. The spectra were compared
to spectra obtained on blanket samples annealed at
increasing temperatures up to 550 °C. A link between the
annealing process, changes in the material’s structure, and
device behavior during cycling was established. “This is a
major advance that brings new light to the mechanisms
that underpin switching and failure in
chalcogenide OTS memory devices,”
said CEA-Leti’s Gabriele Navarro.
“This is a prime example of why
working with academic research
labs is so important. In addition to
it being a real pleasure to work with
Abdelkader Souifi’s team, they bring
Gabriele
hands-on experience with earlier-stage
Navarro
experiments like this one.”
Souifi Abdelkader
INSA Lyon’s Abdelkader Souifi said, “My main task is
to teach engineering students in our Materials Science
and Engineering department. The partnership with
CEA-Leti is solid, and our PhDs benefit directly in the
form of job opportunities with CEA-Leti’s industrial
R&D partners. At INSA Lyon, only around 10% of our
students are majoring in advanced nanotechnologies.
Working with CEA-Leti also helps us attract top
candidates to our programs. When we send our
students to CEA-Leti, we know they are going to be
satisfied. On a more personal level, after 20 years, I
feel more like a colleague than a partner.”
New, detailed understanding of switching and
failure—and PhD student success stories
The partners’ latest findings show that the increase
in Sb-Sb and Sb-Se bonds are mainly responsible for
the switching mechanism in the alloy. The gradual Sb
segregation and potential Sb2Se3 crystallization observed,
supported by TEM/EDX analyses and confirmed by
XRD patterns and Raman spectra obtained on blanket
samples, are the main culprits behind device failure. The
joint research that led to this advance was born some
20 years ago out of a student internship and, later, a first
co-supervised PhD dissertation that led to others.
Raman spectra acquired on the OTS device at different numbers
of cycles (virgin, after forming, and up to 1,000 cycles). The main
features are highlighted: Sb-Se, Ge-Se, Sb-Sb, and Se-Se.
Source: Journal of Applied Physics
Laguna, C., et al. Inside the ovonic threshold switching (OTS) device
based on GeSbSeN: Structural analysis under electrical and thermal
stress. (2023). doi.org/10.1063/5.0134947
15
SCIENTIFIC
REPORT
2023
© CEA
Reimagining computing to enable new Edge AI scenarios
A team comprising CEA-Leti, three CNRS laboratories,
and startup HawAI.tech leveraged in-memory and
near-memory computing techniques to do two things:
First, minimize data movement—one of AI’s particularly
energy-hungry aspects—to drastically reduce energy
consumption and second, implement a Bayesian framework
that, unlike conventional neural networks, is explainable.
“AI researchers around the world
are on a quest for energy-efficient,
secure computing solutions capable
of overcoming traditional hardware’s
struggles with AI algorithms. These
solutions are a prerequisite to moving
AI computing out of the cloud—where
Tifenn
data is exposed to privacy and security
Hirtzlin
threats—and onto devices,” said
CEA-Leti’s Tifenn Hirtzlin, formerly of C2N. This hybrid
CMOS-memristor demonstrator circuit excels in safetycritical situations, where high uncertainty is present, little
data is available, and explainable decisions are required. It
could open the door to new Edge AI solutions for medical
sensors, industrial safety monitoring, and other critical use
cases.
A cover-worthy breakthrough
Our breakthrough solution, which made the cover of
Nature Electronics, is a fully-fabricated hybrid CMOSmemristor circuit combining 2,048 memristors and
30,080 transistors. The architecture is based on fully
distributed memory using only local memristor arrays as
memory elements. By employing stochastic computing
principles and optimizing data movement, we achieved
energy improvements of several orders of magnitude
compared to traditional implementations. Additionally, our
system capitalizes on non-volatile memory, for instant on/
off capabilities that allow inference almost immediately
upon powering on and conserve energy by completely
shutting down when idle—a revolution in energy efficiency.
The objective of CEA-Leti’s groundbreaking research was to
demonstrate the feasibility of near-memory implementation
of Bayesian models on a test circuit, opening the door to
new embedded AI solutions for critical use cases. Bayesian
reasoning is a probabilistic framework, that excels in “small
data” situations by leveraging prior expert knowledge and
providing explainable results. It can also estimate prediction
certainty—an asset that neural networks don’t possess. Until
now, however, implementing Bayesian reasoning in nearmemory computing scenarios has been challenging due to
high memory access requirements.
16
© CEA
Solving the challenges of efficient near-memory
Bayesian computing
Optical microscopy photograph
of the Bayesian system die.
Source: Nat Commun 14, 7530
Bonnet, D., et al. Bringing uncertainty quantification to
the extreme-edge with memristor-based Bayesian neural
networks. (2023). doi.org/10.1038/s41467-023-43317-9
01 I MATERIALS AND DEVICES FOR ENERGY EFFICIENT COMPUTING
On-chip inference and learning at the Edge
The rapid growth of artificial intelligence has spawned
smart algorithms that enable machines to learn
autonomously and interact with the environment, adjusting
their synaptic weights. This brain-like process of learning
and inference can be replicated, using special memory
devices to store the synaptic weights. The problem is
that today’s memory technologies cannot simultaneously
excel at both learning and inference. Some, suitable for
inference, deteriorate quickly with learning activities, while
others are optimized for learning but perform poorly during
inference. This limitation has prevented neuromorphic
systems with emerging memories from possessing active
learning abilities. These systems must be pre-programmed.
RRAM and FeRAM a winning combination
In joint research with smart digital systems experts at
CEA-List, we co-integrated resistive random-access
memory (RRAM) and one transistor-one capacitor (1T-1C)
ferroelectric random-access memory (FeRAM) devices.
RRAM, with its non-destructive readouts, is excellent for
inference but falls short in the learning phase due to limited
write endurance and high programming energy. In contrast,
FeRAM offers the advantage of ultra-low programming
energy and high endurance, but a data-destructive reading
process makes the technology unsuitable for inference
tasks. Combining the two could overcome the limitations
of current memory devices, but this type of co-integration
brings a new set of challenges.
Scalability and CMOS Back End Of Line (BEOL)
compatibility
In this kind of integration scenario, the creation of multiple
new masks and additional process steps adds complexity
and costs. We developed a novel memory stack using
ferroelectric Si-doped hafnium oxide so that the RRAM
and FeRAM could be co-integrated in the same BEOL
without extra masks. This hybrid memory stack enables the
transformation of devices fabricated as FeRAM to RRAM
through a unique electrical forming operation.
Cardiac arrythmia test case produces compelling
results
A new synaptic circuit that facilitates on-chip learning
in binarized neural networks (BNNs) was designed and
tested. It uses FeRAM to store the nuanced weights
during learning and RRAM to hold the binary weights for
inference. The system takes advantage of the specific
properties of each memory type, ensuring energy-efficient
operations and stability where needed. We tested this
innovative circuit on cardiac arrhythmia detection, where it
met the demands of constrained hardware. This advance
is a significant step toward implementing and designing
energy-efficient neural networks capable of learning and
inference at the edge, surmounting the limitations of
current memory technologies and potentially enabling
continuous learning and adaptation in Edge AI systems.
Further reading
• Laguna, C., et al. Inside the ovonic threshold switching (OTS)
device based on GeSbSeN: Structural analysis under electrical
and thermal stress. Journal of Applied Physics, 133(7), 074501.
2023. doi.org/10.1063/5.0134947.
• Harabi, K.-E., et al. A memristor-based Bayesian machine.
Nature Electronics, 6(1), 52-63. 2023.
• Martemucci, M., et al. Hybrid FeRAM/RRAM Synaptic Circuit
Enabling On-Chip Inference and Learning at the Edge. Paper
presented at the International Electron Devices Meeting (IEDM).
2023.
17
SCIENTIFIC
REPORT
2023
ADVANCES IN QUANTUM
HARDWARE
CEA-Leti quantum partners
CEA-Irig, CEA-List, CNRS, Institut
Néel, Inria, IMEP-LAHC, FhG-IPMS,
University of Pavia, Italy, Soitec,
STMicroelectronics, Quobly
The path toward millions
of qubits superconducting
vs. Si spin qubits
• Superconducting qubits are the
conventional favorites (Google, IBM)
and the current state of the art is
in the 1,000s of qubits.
• Silicon spin qubits (CEA-Leti’s bet)
got a late start, and the current state
of the art is around 10 qubits,
and the technology is scalable.
• Photonic qubits, an alternative approach,
are currently in the 100s of qubits with
discrete components. Scalability will
come through integrated photonics.
18
Quantum computing—a quintessential deep tech
field—continued to make headlines in 2023, with
hundreds of quantum startups around the world
raising billions in capital. CEA-Leti continued to drive
advances in semiconductor-based qubits and photonic
quantum integrated circuits in 2023, working with
academic research labs, startups, major corporations,
and EU project consortia to bring the reality of an
operable quantum computer closer.
The anxiously-awaited quantum computer will revolutionize
computing in fields like medicine and energy, solving
complex problems that conventional computers cannot. The
promise of quantum is that exponentially-more-powerful
computing will help overcome some of the technological
hurdles to solving the major challenges facing our society.
Our objective at CEA-Leti is to develop a fully integrated
technology on silicon offering a viable path to industrial
manufacturing of quantum communication and quantum
computing technologies.
In 2023 we made strides in FD-SOI-based spin qubits—the
chosen technology of CEA-Leti spinoff Quobly, which raised
€19 million in capital in 2023, placing Grenoble at the center
of the silicon qubit movement. We also made strides in the
cryogenic electronics necessary for quantum processors and
in photonic quantum integrated circuits.
© diuno - Adobe Stock
01 I MATERIALS AND DEVICES FOR ENERGY EFFICIENT COMPUTING
CEA-Leti is developing key materials,
structures, and process flows for silicon
qubits, making advances in 28Si layers
and c-Ge/SiGe heterostructures for spin
qubits. These advances could ensure that Si
CMOS VLSI technology, which is at a high
manufacturing readiness level (MRL),
can be used for the monolithic fabrication
of huge numbers of group-IV semiconductor
qubits. Along the same lines, CEA-Leti
is also investigating device design to ensure
the desired performance. This research
is being conducted at CEA-Leti with
CNRS-Institut Néel, CEA-Irig
and Quobly, a quantum startup
spun off from CEA-Leti and CNRS.
A new generation of CEA-Leti Si MOS
spin qubit devices
Based on the feedback from the experiments performed
on the Si MOS spin qubit devices fabricated in CEA-Leti
cleanrooms, we identified additional improvements to
increase device performance and fabrication yield.
Top-view and cross-section TEM images
of the new-generation device.
© CEA
Silicon spin qubits
19
SCIENTIFIC
REPORT
2023
© CEA
Based on the feedback from the experiments performed
on the Si MOS spin qubit devices fabricated in CEA-Leti
cleanrooms, we identified additional improvements to
increase device performance and fabrication yield.
We fabricated a new generation of the devices with finely
tuned processes and with different etched patterns in
the Si nanowire to do away with the spurious couplings
between the qubits and nearby charge sensors. The
devices were characterized at room and cryogenic
temperatures, and the results confirmed that the devices
are functional and can still perform charge sensing with the
new etched areas. Additionally, no trace of the spurious
couplings was found. Finally, given these promising results,
numerical simulations were carried out to test the impact
of several possible improvements. “Remarkably, the
devices were demonstrated to be
functional on the first attempt, so
different variations were simulated
to predict an optimal geometry that
should improve their functioning
even more. These results indicate a
significant upgrade to the Si MOS
spin qubit devices fabricated at
Biel Martinez
CEA-Leti, and should bring Quobly
one step closer to the demonstration of many-qubit
experiments,” said CEA-Leti’s Biel Martinez.
Advances in semiconductor
quantum-dot-based spin qubits
One approach to scalable quantum being investigated
at CEA-Leti is spin in semiconductor quantum dots. Our
research with CEA-Irig produced two key advances in 2023,
both of which were published in Nature Nanotechnology.
The first was longer coherence times achieved by varying
the magnetic field orientation to reveal “sweet spots”
20
where the impact of charge noise is lower, and electricdipole spin control is still efficient. The second was a spincoupling rate well above the spin-photon decoherence
rate. Together, these results open up a realistic new
pathway to the development of circuit quantum
electrodynamics with spins in semiconductor quantum
dots.
Optimizing 28Si layer production
and c-Ge/SiGe heterostructures
The ability to obtain high-purity 28Si layers and c-Ge/
SiGe heterostructures is vital to improving the coherence
times of electron spins in quantum dots and, as a result,
quantum processor performance. “The 28SiH4 gas
used to grow the layers is scarce
and expensive. Our research also
addresses strategies to reduce
the consumption of this gas.
In parallel, we are developing
c-Ge/SiGe heterostructures for
hole-spin qubits. The objective
here is to generate a highmobility, two-dimensional hole
Jean-Michel
gas in a compressively-strained
Hartmann
Ge quantum well embedded in SiGe. The ability to
fine-tune the layers and electric fields would enable
precise manipulation of individual wells, vital to qubit
functionality,” said CEA-Leti’s Jean-Michel Hartmann.
UtopikPhoto / CEA
A new generation of CEA-Leti Si MOS
spin qubit devices
01 I MATERIALS AND DEVICES FOR ENERGY EFFICIENT COMPUTING
The development of efficient, scalable quantum
computers will depend in part on a deeper
understanding of how CMOS technologies like
FD-SOI behave at cryogenic temperatures.
CEA-Leti has been investigating the role of
carrier statistics and mobility variations in
the design and understanding of cryogenic
electronics. CEA-Leti and IMEP-LaHC, a
laboratory affiliated with the French National
Center for Scientific Research (CNRS), Grenoble
INP - UGA, and Université Savoie Mont Blanc
gained new insights into the zero-temperature
coefficient (ZTC) observed in FD-SOI MOSFETs
at cryogenic temperatures.
© IMEP-LEHC
Cryogenic electronics
Gérard Ghibaudo
“Our strong partnership, supported by joint European
projects, the French Labex Minos initiative, and
the co-supervision of PhD students, has allowed us
not only to benefit from pooled financial resources
and manpower, but also to reinforce our personal
relationships,” Ghibaudo said.
Tomorrow’s quantum computers will require new
low-temperature integration paradigms
Quantum bits—or qubits—operate at very low
temperatures, on cryogenically-cooled chips. And the
closer the cryogenic components and conventional
electronics are to each other, the less room-temperature
wiring is needed in these systems. Integrated circuits
that can operate at much lower temperatures could help
close this gap, ultimately enabling superconducting and
silicon spin qubits to coexist on a single chip. This kind of
hardware, where cryogenic electronics and qubits work
hand in hand, will facilitate extensive qubit matrix indexing
and support the deployment of large-scale quantum
processors. CEA-Leti and Gérard Ghibaudo’s team at
IMEP-LaHC are helping bridge the gap in our physical
understanding and move cryogenic CMOS circuit design
capabilities forward. Ghibaudo, who has been working with
CEA-Leti on characterization since he was a PhD student in
1979, is pleased with the latest advances this decades-long
partnership has produced.
FD-SOI a promising technology
Fully depleted silicon-on-insulator (FD-SOI), with its ability
to adjust threshold voltage through back biasing, has
enabled generations of high-performance, energy-efficient
electronics—especially at low temperatures. But there are
hurdles to cryogenic CMOS chips, not least of which is a
lack of specialized process design kits (PDKs) tailored to
cryogenic operation across different technology nodes.
“Extensive electrical characterization is a prerequisite to
the development of future cryogenic compact models,”
IMEP-LaHC is a valuable partner in this respect,” said
CEA-Leti’s Mikael Cassé. “Another approach currently
being explored is to provide designers with analytical
and physics-based models to optimize circuits for
cryogenic operation.”
21
SCIENTIFIC
REPORT
2023
Understanding the zero-temperature
coefficient (ZTC)
In this research, our goal was to unravel the zerotemperature coefficient (ZTC) observed in FD-SOI
MOSFETs at cryogenic temperatures. The ZTC represents a
point where gate-to-channel capacitance and drain current
remains constant across a broad temperature range.
Here’s what we learned: The ZTC point in the capacitance
curves is inferred to the sub-band occupation probability
(controlled by the Fermi-Dirac function), which is
temperature-independent for a given gate voltage. When
the Fermi level increases with temperature, compensating
for the temperature decrease, the ZTC emerges.
“We also looked at the effects of carrier mobility on the
ZTC in drain current transfer characteristics, factoring
in the temperature-dependence of carrier mobility
and different scattering mechanisms. Under specific
conditions, such as phonon scattering-limited mobility,
the ZTC point can be observed in the drain current
characteristics, even if its origin resides in the carrier
statistics. However, in the presence of other scattering
mechanisms, such as Coulomb and neutral defect
scattering, the ZTC point no longer exists,” said Cassé.
Photonic quantum
integrated circuits
Silicon photonics has the potential to
support quantum communications, either
for the exchange of secret keys for ultrasecure quantum communication networks
or to link distributed quantum processors.
Miniaturized systems with on-chip quantum
generation, encoding, and detection will be
vital to the massive deployment of quantum
communications. In quantum computing,
silicon photonics could provide a strong
foundation for photonic qubits that
could offer a path to low decoherence
and room-temperature operation.
Challenges to building quantum integrated circuits
© UtopikPhoto / CEA
At CEA-Leti, we are focusing on quantum integrated
circuits for the generation, encoding, processing, and
detection of quantum states of light. “Quantum light can
be generated on silicon using nonlinear processes, but
achieving high generation rates remains challenging.
In addition, high-performance filtering and
demultiplexing solutions are needed to
provide quantum photon states that can be
further manipulated on-chip for encoding
and computation,” said CEA-Leti’s Ségolène
Olivier. “The integrated photodetectors
currently used in telecoms and datacoms will
have to be replaced by much more sensitive
Ségolène Olivier single-photon detectors,” Olivier said.
22
01 I MATERIALS AND DEVICES FOR ENERGY EFFICIENT COMPUTING
On-chip quantum-grade components
In collaboration with the University of Pavia, Italy, we
developed integrated sources of entangled photon pairs
on silicon based on the nonlinear spontaneous fourwave mixing process. They emit quantum light at around
1,550 nm with a MHz generation rate for one couple of
paired wavelengths, and up to 4 GHz for multiple couples
of paired wavelengths. We also developed a low-loss
integrated demultiplexer to separate the signal from
the idler frequencies of the multiple photon pairs and
developed an integrated pump filter, obtaining a rejection
ratio above 75 dB. Finally, for quantum light detection, we
developed a first generation of superconducting nanowire
single-photon detectors integrated on silicon waveguides
in collaboration with CEA-Irig. We obtained on-chip
detection efficiency exceeding 80% for a dark count rate
under 100 Hz at a wavelength of 1,550 nm. These results
were obtained on industrial-grade 200 mm and 300 mm
cleanroom equipment using a CMOS-compatible process
flow, marking a step toward cost-effective photonic
integrated quantum technologies.
Further reading
• Bertrand, B., et. al. Paper presented at the International
Electron Devices Meeting (IEDM) conference, San Francisco,
US. 2023.
•Brisson, V., et al. NbN Waveguide-Integrated
Superconducting Nanowire Single-Photon Detectors on
200 mm SOI Wafers. Paper presented at the European
Conference on Optical Communications, Glasgow, UK. 2023.
• Cassé, M., et al. FDSOI for cryoCMOS electronics:
device characterization towards compact model.
In International Electron Devices Meeting (IEDM)
(pp. 34.6.1-34.6.4). San Francisco, CA, USA. 2022.
doi: 10.1109/IEDM45625.2022.10019322.
• Catapano, E., et al. On the Zero Temperature
Coefficient in Cryogenic FD-SOI MOSFETs. IEEE Transactions
On Electron Devices, 70(3), 845-849. 2023.
doi: 10.1109/TED.2022.3215097.
• Catapano, E., et al. TCAD simulations of FDSOI devices
down to deep cryogenic temperature. Solid-State Electronics,
194, 108319. 2022. doi: 10.1016/j.sse.2022.108319.
• Gianini, L., et al. Silicon-Integrated Multiplexed Source
of Time-Energy Entangled Photon Pairs with Emission Rate
over 1 GHz. Paper presented at the European Quantum
Technology Conference, Hannover, Germany. 2023.
(Paper to be published in 2024).
• Hartmann, J.-M., et al. Epitaxy of Group-IV Semiconductors
for Quantum Electronics. ECS Transactions, 111(1), 53. 2023.
doi: 10.1149/11101.0053ecst.
• Olivier, S., et al. Building a quantum-grade integrated
photonics platform to address the technological challenges
of quantum communications and computing. Invited talk at
the Photonics West Conference, San Francisco, US. 2023.
• Piot, N., et al. A single hole spin with enhanced coherence
in natural silicon. Nature Nanotechnology, 17(10), 1072-1077.
2022.
• Virot, L., et al. High rejection filters based on cascaded ring
resonators in a 300 mm silicon photonics platform. Paper
presented at the Photonics West Conference, San Francisco,
US. 2023.
• Yu C., et al. Strong coupling between a photon and a hole
spin in silicon. Nature Nanotechnology, 18(7), 741-746. 2023.
23
SCIENTIFIC
REPORT
2023
World first: nanoscale electrostatic potential
mapping in active micro-LEDs
UtopikPhoto / CEA
CEA-Leti research
director
Micro-LEDs play pivotal roles in
lighting, displays, and detectors.
Device performance is intricately
tied to internal structures and
electrostatic potentials, which—
amid increasing miniaturization—
require more and more precise
measurement techniques. CEA-Leti
made a significant stride in this
direction, utilizing a combination of
transmission electron microscopy
(TEM) and off-axis electron
holography to obtain nanometerresolution in situ measurements
of the electrostatic potentials in a
red-emitting AlInGaP micro-LED.
Advanced characterization techniques instrumental in this
world-first
This research focused on micro-LEDs. A fully processed red-emitting
AlInGaP micro-LED with well-established properties verified through
standard luminescence techniques was examined. The device was
prepared for in situ TEM analysis using a focused ion beam, ensuring a
thin, operable region for observation. Advanced electron holography
acquisition parameters were employed to achieve a balance between
high spatial resolution and signal-to-noise ratio, facilitating the
observation of electrostatic potentials during operation.
From device to
TEM experiment
to theory.
© CEA
David Cooper
Measurement plus simulation in combination deliver new
information
Impact
Electric potentials were observed at
the nanoscale for the first time ever in
working devices, providing clear insights
into how potential changes during
micro-LED operation. This world-first
advances our understanding of microLED operation and opens new avenues
for the optimization and development
of future opto-electronic devices.
Research partners
N/A
Further reading
Our in situ measurements and simulations revealed the evolution of
electrostatic potentials within the micro-LED as it transitioned from a
non-emissive to a light-emitting state. This data was correlated with
the applied bias, providing a direct visual representation of the device’s
operational mechanisms. The potentials measured were used to confirm
the simulations of band structure and carrier injection in the devices.
The ability to “see” how a micro-LED works from the inside
has wider implications
When you think of TEM, atoms spring to mind first. However, we used
an electron biprism to create interference between the electrons
passing through the sample and a reference electron wave to generate
an electron hologram to “see” the changes in potential in the device
during operation. While this project focused specifically on micro-LEDs
for displays, the methods developed could be used to optimize and
develop other semiconductor devices.
• Denaix, L., et al. Inversion of the Internal Electric Field Due to Inhomogeneous Incorporation of Ge Dopants
in GaN/AlN Heterostructures Studied by Off-Axis Electron Holography. ACS Applied Materials & Interfaces,
15(8), 11208-11215. 2023.
• Cooper, D., et al. Mapping of the Electrostatic Potentials in a Fully Processed Led Device with nm-Scale
Resolution by In Situ off-Axis Electron Holography. Small Methods, 2300537. 2023.
24
01 I MATERIALS AND DEVICES FOR ENERGY EFFICIENT COMPUTING
3D integration: pulsed-laser annealing for
accurate control of silicon recrystallization
Sébastien Kerdilès
CEA-Leti is continuing to drive advances in
3D integration with the development of new
processes. Recently, nanosecond pulsed-laser
annealing was applied in the melt and submelt regimes to accurately control silicon
recrystallization, potentially boosting chip
density and performance while limiting heat
diffusion during fabrication.
3D integration presents severe thermal budget
limitations
Three-dimensional or vertically-stacked integrated circuits
are currently one of the main paths toward more-thanMoore devices. However, 3D integration introduces
significant thermal challenges, particularly for the upper
layers of transistors. Traditional annealing processes,
involving temperatures around 1,000 °C, can damage
the bottom-layer transistors. CEA-Leti is pioneering
the use of UV laser annealing, utilizing extremely short
pulse durations to concentrate heat at the top surface,
preserving the integrity of the underlying structures.
This innovative approach is effective at lowering the
thermal budget required for top-layer fabrication, thereby
safeguarding the thermal stability of the entire system.
Two approaches to pulsed-laser annealing to
obtain silicon junctions
To obtain high-performance silicon junctions compatible
with 3D integration, we are investigating two main
approaches using pulsed-laser annealing: in the melt
regime and the sub-melt regime.
•
In the melt regime, the silicon region to be doped
is brought into the liquid phase with a single highenergy laser pulse, followed by recrystallization.
•
In the sub-melt regime, multiple pulses are applied to
trigger dopant activation and crystal healing.
Both approaches have their advantages and
disadvantages. We successfully demonstrated heavy
phosphorus doping. Plus, with SOI structures, whose
silicon layer is very thin, the optimal process conditions
also happened to correspond to the near full-melt of the
SOI layer, which means that perfect crystallinity can be
obtained. Controlling melt depth accurately is crucial to
limiting thermal dissipation in the device. Uniform laser
beams with excellent repeatability are a must, as are well-
© CEA
UtopikPhoto / CEA
CEA-Leti research engineer
calibrated numerical simulations. Recent improvements in
our models have supported even better results.
Ion implantation for doping and amorphization
We also investigated a solid-state approach, amorphizing
and doping SOI structures via ion implantation. Here, we
used nanosecond and microsecond lasers to induce solidphase epitaxial regrowth, applying several pulses at the
same location to gradually recrystallize the silicon, again
obtaining very high dopant concentrations, and, thanks
to a new strategy of continuously adjusting laser energy
density, an optimized silicon recrystallization rate.
Impact
Our recent advances in nanosecond laser annealing will
contribute to generic modules for 3D integrations or
any device fabricated on top of a traditional CMOS. The
use of such an out-of-equilibrium annealing technique
enables ultimately high active dopant concentrations
relevant for advanced CMOS technologies.
Research partners
LASSE, a SCREEN company; CNRS-LASS (France) and
CNR-IMM (Italy) under the EU MUNDFAB project.
Further reading
• Ricciarelli, D., et al. Impact of surface reflectivity on the ultrafast laser melting of silicon-germanium alloys. Materials Science
in Semiconductor Processing, 165, 107635. 2023.
• Chery, N., et al. Study of recrystallization and activation
processes in thin and highly doped silicon-on-insulator layers by
nanosecond laser thermal annealing. Journal of Applied Physics,
131(6), 065301. 2022.
• Calogero, G., et al. Multiscale modeling of ultrafast melting
phenomena. npj Computational Materials, 8(1), 36.
• Alvarez-Alonso, A., et al. (2022). Optimization of solid-phase
epitaxial regrowth performed by UV nanosecond laser annealing.
MRS Advances, 7(36), 1310. 2022.
• Tabata, T., et al. Microsecond non-melt UV laser annealing for
future 3D-stacked CMOS. Applied Physics Express, 15(6), 065301.
2022.
• Tabata, T., et al. Solid-phase recrystallization in Arsenic ion
implanted SOI by microsecond laser annealing. IEEE Journal on
Electron Devices Society, 10, 712. 2022.
25
SCIENTIFIC
REPORT
2023
MARKET
NEWS
FROM OUR R&D PARTNERS
EXTENDING MOORE’S LAW: CEA-LETI & INTEL TO
DEVELOP ATOMICALLY THIN 2D TMDS ON 300 MM
WAFERS USING LAYER TRANSFER TECHNOLOGY
FOR FUTURE TRANSISTOR SCALING
© B. Lavit / CEA
Grenoble, France – June 19, 2023.
CEA-Leti and Intel today announced a joint research project to develop layer transfer
technology of two-dimensional transition-metal dichalcogenides (2D TMDs) on 300 mm wafers
with the goal to extend Moore’s Law beyond 2030.
Robert Chau, Intel Senior Fellow
in Technology Development and Director
of Intel Europe Research, said:
“As we are relentlessly pushing Moore’s Law, 2D TMD material is a
promising option for extending the limits of transistor scaling in the
future. This research program focuses on developing a viable 2D TMDbased technology in 300 mm for future Moore’s Law transistor scaling.“
https://urlz.fr/nKFK
26
© ImageFlow / IRStone - Adobe Stock
01 I MATERIALS AND DEVICES FOR ENERGY EFFICIENT COMPUTING
QUOBLY RAISES €19 MILLION
Quobly (formerly Siquance) has successfully raised €19 million. The highest
amount ever raised by an CEA-Leti start-up for a first funding round.
The funding will accelerate the development of a fault-tolerant quantum
processor for universal quantum computing.
https://urlz.fr/nKH9
www.quobly.io
WEEBIT NANO AND CEA-LETI QUALIFY
RERAM MEMORIES FOR AUTOMOTIVE
APPLICATIONS
Source: ViPress.net
Published by Pascal Coutance. August 22, 2023.
7/7, Automotive, Component, MT, Semiconductor, Techno.
The Israeli company, which has a subsidiary in Grenoble, has qualified
its ultra-low-power ReRam memories, made by its R&D partner, up to a
temperature of +125°C specified for automotive-grade non-volatile memories.
https://urlz.fr/nMYa
27
© Tatiana - Adobe Stock
SCIENTIFIC
REPORT
2023
28
02 I SMART POWER DEVICES
SMART POWER
DEVICES
Gaël Pillonnet
© UtopikPhoto / CEA
Scientific Advisor to
the Silicon Components Division
With the electrification of
the economy well underway,
CEA-Leti’s historic expertise in
silicon supported advances in
everything from substrates and
power components to converter
topologies and energy storage in
2023. We continued to lead the
way in silicon carbide substrate
research, with notable advances in
transferred silicon carbide substrates.
We also made breakthroughs
in insulated recessed-gate GaN
transistors for more reliable power
components, investigated highfrequency piezoelectric materials for
increased power converter density,
and introduced cutting-edge siliconbased microbattery performance
optimization tools.
29
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REPORT
2023
CEA-Leti presents advances
in transferred SiC substrates for electronics
and photonics at ICSCRM 2023
© CEA
CEA-Leti engineer
CEA-Leti’s cornerstone research on
silicon carbide substrates initially
gained traction in 2019 with
Soitec on booming demand from
the electric vehicle market and a
scarcity of monocrystalline silicon.
Today, with four presentations
at ICSCRM 2023 showcasing
pioneering advances in transferred
silicon carbide substrates for
electronics and photonics, CEA-Leti
continues to lead the way in silicon
carbide and thin film transfer
technologies.
Impact
The development of thin SiC film transfer
techniques could provide a new supply
of SiC wafers and an innovative toolbox
for enhancing the performance of
state-of-the-art technologies for power
electronics, photonics, quantum, and
nanoelectronics.
A history advancing innovative substrates from lab to fab
CEA-Leti’s successful partnership with Soitec led to the company’s
launch of a SiC plant in Bernin, France, in less than five years.
Although these developments were kept confidential at the time,
more recent advances were shared at ICSCRM 2023, the International
Conference on Silicon Carbide and Related Materials, where more
than 700 physicists, engineers, scientists, and students came to discuss
SiC and other innovative materials. Of the four abstracts CEA-Leti
submitted to ICSCRM 2023, two earned spots for oral presentations,
and two for poster presentations, providing a panorama of the latest
advances coming out of CEA-Leti labs.
Schematic view of the transferred SiC substrates developed
at CEA-Leti. (a) SiCOI substrates for photonics and quantum;
(b) vertically conductive SmartSiC™ substrates for power electronics.
© CEA
Julie Widiez
Progress in SiC integration a key highlight at ICSCRM
The four CEA-Leti presentations at ICSCRM illustrate significant
strides in silicon carbide (SiC) integration for electronic and photonic
applications, exploring the development of SiC-on-Insulator (SiCOI)
structures using ion slicing technologies. These structures constitute
a valuable tool to investigate the electrical properties of transferred
SiC layers. A deeper understanding of the impacts of ion implantation
and annealing processes will be vital to optimizing SiC-based
device performance, and, further down the line, driving advances in
applications where SiC plays a pivotal role, from power electronics to
photonics and even quantum.
Building the future of SiC together
The advances presented at ICSCRM were not pioneered by CEA-Leti
alone; an entire ecosystem of partners has contributed to this
groundbreaking research. In addition to Soitec (for power applications),
CEA labs LIFT and LAPS worked closely with the CEA’s LITP lab (on
test vehicles on the PFP platform), CEA-Irig (on high-temperature
annealing), plus CEA experts in bonding, implantation, and thermal
annealing. CEA-Leti also has a number of SiC partnerships with
academic research labs and/or companies (such as the MobiSiC
and Transform projects). Finally, CEA-Leti is working on photonic
applications with C2N, a CNRS laboratory located in Paris-Saclay.
30
02 I SMART POWER DEVICES
Further reading
• Gelineau, G., “Processing and electrical characterization of SiC-on-Insulator
structures.”
This study focuses on SiC-on-Insulator (SiCOI) structures fabricated using ion slicing
technology. Thin film transfer techniques have gained popularity in SiC processing
for power electronics and optical devices. The electrically insulating oxide layer
between the receiving substrate and the transferred layer allows for the measurement
of electrical properties affected by ion implantation before material recovery.
Electrical characterization has demonstrated improved properties at higher annealing
temperatures, indicating progressive restoration of the transferred material’s
electrical characteristics. SiCOI substrates prove to be valuable for investigating thin
4H-SiC layers, providing insights into electrical behavior and potential applications in
power electronics and optical devices.
• Masante, C., “Electrical characterization of 200 mm 4H-SiC-on-polycristalline SiC
wafers bonding interface.”
This study focuses on the electrical characterization of 200 mm 4H-SiC-onpolycrystalline wafers. These substrates possess lower resistivity, which reduces
device access resistance and allows for flexible backside processing for ohmic contact
fabrication. A lateral design test vehicle with circular electrodes was employed to
extract the bonding interface resistivity. FE-modeling techniques were used to
calculate resistance and determine the bonding interface resistivity. The results
indicate a low bonding interface resistivity, offering significant resistance reduction
for power devices. Furthermore, backside ohmic contact was achieved without
the need for a silicide layer and high-temperature annealing, providing further
confirmation of the potential of the transferred SiC layer on poly-SiC substrates in
power electronics applications.
• Prudkovskiy, V., “Confirmation of the growth mechanism of the buffer layer in
epitaxial graphene on SiC.”
Epitaxial graphene on SiC, referred to as epigraphene, holds substantial promise
for nanoelectronic applications. To ensure successful application, comprehending
the growth mechanism of epigraphene on SiC is paramount. This study confirms the
thermal decomposition epitaxy process for epigraphene growth on SiC, in which the
SiC substrate serves as a carbon source. This growth procedure yields a multilayer
graphene stack. Furthermore, the study reveals that the transition from graphene to a
‘buffer’ layer takes place during the cooling down phase. Subsequent annealing of the
sample preserves the integrity of the graphene-SiC interface. This research provides
invaluable insights into the growth process of epigraphene on SiC and its potential for
nanoelectronic applications.
• Huet, S., “Demonstration of SiC-on-insulator substrate with Smart Cut™
technology for photonic applications.”
SiC-on-insulator (SiCOI) substrates utilizing Smart Cut™ technology facilitate costeffective and high-quality photonic circuits. The produced 150 mm SiCOI wafers
exhibit exceptional quality, boasting low roughness and minimal defects. Waveguides
and microring resonators are intricately designed on SiCOI substrates, with
simulations indicating promising modal behavior and a high power density conducive
to nonlinear optical effects. This work validates the successful transfer of a 500 nm
monocrystalline SiC layer onto an insulating SiO2 layer, thereby opening avenues for
efficient and commercially viable SiC-based photonic applications.
31
SCIENTIFIC
REPORT
2023
Insulated recessed gate GaN power
transistors enable promising
normally-OFF architecture
Pedro Fernandes
Paes Pinto Rocha
© CEA
CEA-Leti PhD
candidate
The size, energy efficiency, reliability, and integration
requirements for power components are tougher than
ever, and the search for breakthroughs that will lead
to more advanced normally-OFF architectures for a
wide variety of markets is underway. CEA-Leti and
STMicroelectronics made advances on an insulated
recessed-gate GaN (gallium nitride) power transistor
that will improve device reliability.
Fully-recessed MIS gates could solve GaN power transistor
overvoltage reliability problems
Impact
Insulated recessed-gate GaN power
transistors are poised to revolutionize
power conversion for solar energy, onboard chargers, USB-C chargers, data
centers, and more. CEA-Leti, CNRS, and
STMicroelectronics brought advanced
etching and dielectric deposition
techniques to a technology that holds
immense promise for the future of power
electronics.
Research partners
STMicroelectronics, CNRS.
32
According to the Yole Group’s Power GaN 2022 report, the GaN power
component market is expected to see double-digit growth over the
next several years. As costs come down and performance improves,
GaN devices will make increasing inroads into the consumer power
supply, automotive, and telecoms/datacoms markets, the report
posits. Although GaN-on-Si power transistors offer smaller devices and
higher power densities than silicon MOSFETs, the conventional p-GaN
gate architecture is plagued by reliability issues, not least of which
is a tendency to fail under even slight overvoltages. Fully-recessed
MIS gate GaN power transistors also offer a wider gate voltage swing
and lower gate leakage current than silicon MOSFETs, making them a
promising solution. CEA-Leti contributed to a number of advances with
STMicroelectronics that will help position the semiconductor giant to
better address the booming power GaN market.
Review paper highlights a series of recent advances in fullyrecessed MIS gate structures
There are a number of challenges to harnessing all the advantages
of insulated recessed-gate transistors. A primary concern is the
optimization of interfaces between the insulator and AlGaN/GaN
to minimize interface trapping states and enhance current flow.
Controlling the insulator charge is also crucial. The most recent
developments in manufacturing processes have focused on:
•
Wet cleaning, thermal treatment, and plasma treatment to obtain
a higher-quality surface.
•
Low-impact etching and atomic layer etching (ALE) for the gate
recesses.
•
Interfacial layers (AlN, in this case) to further reduce power losses.
•
Alternative materials for thin film dielectric layers to improve
reliability
© V. Guilly / CEA
02 I SMART POWER DEVICES
200mm wafer with insulated recessed-gate GaN power
transistors from CEA-Leti.
All of these process steps—from surface preparation to
etching and the deposition of the dielectric layer—must
be carefully controlled to obtain the desired device
specifications. Proper characterization of the damage
induced by plasma-assisted etching and industriallyviable process integration present additional challenges
that must still be addressed.
The outlook for power electronics
Insulated recessed-gate GaN power transistors have
the potential to redefine power conversion systems
for solar panels, on-board chargers, USB-C chargers,
and data centers. The innovative transistors developed
by CEA-Leti, CNRS, and STMicroelectronics harness
cutting-edge etching and dielectric deposition
techniques and will position STMicroelectronics to drive
adoption of its power GaN products by these markets.
Further reading
• P. Fernandes Paes Pinto Rocha et al., Recent Developments
and Prospects of Fully Recessed MIS Gate Structures for GaN
on Si Power Transistors. Energies 2023, 16, 2978, 2023,
doi: 10.3390/en16072978.
• B. Mohamad et al., Deep Insights into Recessed Gate
MOS-HEMT Technology for Power Applications, 2023
7th IEEE Electron Devices Technology & Manufacturing
Conference (EDTM), Seoul, Korea, Republic of, 2023, pp. 1-3,
2023, doi: 10.1109/EDTM55494.2023.10102971.
• C. Piotrowicz et al., Impact of Gate Morphology on Electrical
Performances of Recessed GaN-on Si MOS channel-HEMT for
Different Channel Orientations, 2023 IEEE 35th International
Symposium on Power Semiconductor Devices and ICs (ISPSD),
Hong Kong, 2023, doi: 10.1109/ISPSD57135.2023.10147642.
33
SCIENTIFIC
REPORT
2023
New model for the optimization
of high-energy-density microbatteries
for IoT devices
Sami Oukassi
© S. Barbier / CEA
CEA-Leti engineer
On-chip batteries will play a key role in our
increasingly connected, electrified, and sustainable
world. As wireless sensor technologies improve and
the Internet of Things expands, the need for tiny,
high-energy-density solid-state integrated batteries
for a rapidly-growing number of use cases is urgent.
CEA-Leti is pushing back the frontiers of on-device
energy storage with innovative battery performance
optimization tools.
Thin-film fabrication and advanced characterization vital to
improving performance
In this research, CEA-Leti fabricated innovative thin-film batteries on
the institute’s TINY platform. Standard microfabrication techniques
and a 200 mm wafer integration process flow were used to produce
sub-square-millimeter microbatteries with a specific areal capacity five
times that of today’s commercially-available products. The batteries
also exhibited exceptional power density and virtually no capacity
fading over hundreds of cycles. These remarkable attributes are ideal
for the longer battery life and small form factor needed for IoT devices.
Thin film batteries fabricated on
200 mm Tiny technology platform.
Impact
Improved thin-film battery performance
is the most promising avenue to meet
growing demand for on-chip energy
storage for IoT. While electrode design
and material offer limited optimization
potential with the currently-available
technologies, charge-discharge protocol
optimizations and associated new circuit
topologies represent viable options.
Research partners
N/A
• Celè, J., et al. Minimal Architecture Lithium
Batteries: Toward High Energy Density Storage
Solutions, 2023, doi: 10.1002/smll.202207657.
34
© CEA
Further reading
02 I SMART POWER DEVICES
Towards viable and more sustainable alternatives
to lithium metal
Lithium metal, used in battery anodes, represents one of
the major environmental hurdles to the adoption of the
technology. Here, we focused on an anode-free model system
utilizing a transition-metal dioxide (LiCoO2), an inorganic
lithium phosphorus oxynitride (LiPON) glass electrolyte, and
a titanium current collector. We were able to demonstrate
full-stack cyclability, making this a viable alternative to
lithium metal. In addition, the maximal discharge capacity
was measured at 1.5 mAh.cm-2, unprecedented for thin film
batteries. Plus, when this anode-free model was coupled
with a 100% active cathode, the battery demonstrated a
volumetric capacity of up to 1,400 Wh/l. We also investigated
different cathode thicknesses: There was a linear correlation
between thickness and delivered capacity for high current
densities of up to 2 mA/cm². Diffusion limitations only
emerged when the state of charge (SOC) fell below 50%,
with thicker electrode designs proving advantageous as long
as the battery charge remains above this threshold. Overall,
this model appears to be very promising for a wide variety of
on-chip energy storage needs.
Modeling the future of microbatteries
A comprehensive physical model, which aligns closely with our
experimental results, was developed based on this research.
It also factors in performance variations depending on design
and architecture, making it a useful and relevant tool for
the optimization of microbatteries for a variety of use cases,
including medical devices.
35
SCIENTIFIC
REPORT
2023
Piezoelectric materials could enable more
compact, efficient power converters
Ghislain Despesse
© CEA
CEA-Leti Research
Director
When operated at high
frequencies, certain piezoelectric
materials display exceptional
quality factors and power
densities. CEA-Leti and an
academic research partner have
been investigating how to bring
these remarkable properties to
power conversion in the form
of a new inductor-free power
converter concept based on
mechanical, rather than magnetic,
energy storage.
Demand for smaller passive components strong on mobile
device growth
One of the most common approaches to achieving more compact,
efficient power electronics has been to target passive components.
Shrinking power converters often means increasing the switching
frequency to allow smaller energy storage elements. While it is true
that inductors, a kind of passive component commonly used in power
electronics, do get smaller as switching frequencies increase, you
eventually hit a wall due to the components’ magnetic properties and
thermal management issues. Not to mention the fact that integrating
efficient magnetic materials and coils in the Ampere range on chips
is difficult—if not impossible—using today’s fabrication processes.
CEA-Leti has been driving advances in piezoelectric materials that
could help solve this problem.
Moving from magnetic to mechanical energy storage not a
straightforward swap
In addition to improved quality and coupling factors, piezoelectric
materials eliminate the need for winding and core assembly, which
means a more streamlined manufacturing process. Plus, their planar
profile makes them ideal for low-profile applications in mobile devices.
This research firmly establishes
piezoelectric resonators for step-down
voltage DC/DC conversion and veryhigh-frequency DC/AC conversion. These
developments, coupled with novel highfrequency control loops, have resulted in
power output of 100 W (170 W transient)
at 1 MHz.
Research partners
Dr. François Costa, Director, Systèmes
et Applications des Technologies de
l’Information et de l’Energie (SATIE), UMR
8029 & professor at Université Paris Est
Créteil.
36
© Satie
Impact
Dr. François Costa
CEA-Leti and SATIE, a Université Paris Est Créteil-CNRS lab
headed by Dr. François Costa, have been working together
for the past several years on piezoelectric resonators (PRs) for
energy storage, looking at ways to solve the new challenges
created by using these tiny mechanical systems instead
of conventional magnetic inductors in power converters.
CEA-Leti’s research with SATIE has led to the development of
new topologies that fully exploit the potential of PRs for power
conversion use cases. “Our lab has been working on piezo
transformers for a long time, but this original research on piezo
resonators is new for us. It is particularly gratifying for me to
have moved from simple observer, sitting on PhD dissertation
juries at CEA-Leti, to a full-fledged partner in this exciting
research,” said Costa.
02 I SMART POWER DEVICES
Most recently, our research produced three new converter
types, one for step-down voltage DC/DC conversion, one
for isolated DC/DC conversion, and one for very-highfrequency DC/AC conversion. Notably, the step-down
voltage converter, which uses PZT (lead zirconate titanate,
a common piezoelectric material), exhibited a power
density increase as the operating frequency rose, achieving
up to 100 W at 1 MHz. The very-high-frequency converter,
which uses a φ2 VHF topology, was combined with a
specific LNO (lithium niobate) resonator and ZVS (zero
voltage switching) regulation loop. The device allowed
us to demonstrate the piezoelectric material’s operation
at 20.6 MHz. Driving is another challenge that must still
be addressed. We also modelled and generalized the
piezoelectric conversion principle to step-up conversion,
step-down conversion, and high/low conversion ratios,
something that is vital to the development of generic
control loops for high-frequency operation. Comparing the
piezoelectric material to an inductor operating at the same
power level revealed a substantial volume gain of more
than sevenfold, underlining the transformative potential of
an innovation born from a particularly fruitful partnership
with an academic research lab. Costa said, “CEA-Leti has
manpower and R&D equipment that goes beyond what
most university labs have access to, with resources you
know will be around for a long time. I am proud of the
world-first we achieved together.”
© CEA
Innovative topologies for two novel piezo-enabled
power converters
Step-down voltage converter
(100 kHz to 1 MHz).
Further reading
• Breton, V., et al. A New Isolated Topology of DC–DC
Converter Based on Piezoelectric Resonators. IEEE
Transactions on Power Electronics, 38(8), 10012-10025, 2023,
doi: 10.1109/TPEL.2023.3276478.
• Bigot, E., et al. Mathematical resolution of a PR-based power
converter. In conf. JNRSE 2023, Paris, France, 2023.
• Touhami, M., et al. A New Topology of DC–DC
Converter Based on Piezoelectric Resonator. IEEE
Transactions on Power Electronics, 37(6), 6986-7000, 2022,
doi: 10.1109/TPEL.2022.3142997.
© CEA
• Massavie, V., et al. Class φ2 ZVS regulation applied to L-Piezo
inverter. In 2022 20 th IEEE Interregional NEWCAS Conference
(NEWCAS) (pp. 490-494). Quebec City, QC, Canada, 2022,
doi: 10.1109/NEWCAS52662.2022.9841975.
Very-high-frequency converter
L-piezo 10.3 kHz).
• Pereira, L. d. A., et al. Operating Frequency Prediction
of Piezoelectric DC–DC Converters. IEEE Transactions
on Power Electronics, 37(3), 2508-2512, 2022,
doi: 10.1109/TPEL.2021.3115182.
• Massavie, V., et al. Comparison between Piezoelectric Filter
and Passive LC Filter in a Class L−PiezoInverter. Electronics,
11(23), 3983, 2022, doi: 10.3390/electronics11233983.
37
SCIENTIFIC
REPORT
2023
MARKET
NEWS
FROM OUR R&D PARTNERS
CONCENTRATED COMPETENCE IN BATTERY
MANAGEMENT: VITESCO TECHNOLOGIES FRANCE
COOPERATES WITH CEA
Toulouse, June 13, 2023.
• ​First results were presented at the EVS36 symposium
from June 11, to June 14, in the United States.
• SWIBA project for better performance and durability of electric vehicles.
• New solution allows to optimize the costs as well as the second life
of the battery in electric vehicles.
After three years of research and development, Vitesco Technologies, a leading international
provider of modern powertrain technologies and electric mobility solutions, presents the
first outcome of its partnership with the CEA (Commissariat à l’énergie atomique et aux
énergies alternatives) in France: Together they have developed a “switched battery" (SWIBA)
management technology that further improves the overall performance of the powertrain of
electric vehicles by increasing their range and reducing their fast charge time, while optimizing
the cost of charging, and increasing the life of the battery. The second life of the battery is also
facilitated.​
Nicolas Léto, innovation project manager
at Vitesco Technologies France said:
“The battery is the key and most expensive element of electric vehicles.
Great progress is being made every day on cell technology. However,
in the current approach, battery packs remain limited because they
are static, and are ultimately only basic energy reservoirs. Our new
SWIBA technology brings dynamic electronic control into the battery
pack to optimize energy management, provide new functionalities and
ultimately reduce its cost and environmental impact.“
https://urlz.fr/nLOL
38
© Blue Planet Studio / AdobeStock
© ImageFlow / IRStone - Adobe Stock
02 I SMART POWER DEVICES
39
SCIENTIFIC
REPORT
2023
MARKET
NEWS
FROM OUR R&D PARTNERS
ELECTRIC VEHICLES:
CEA AND RENAULT GROUP DEVELOP
A VERY HIGH EFFICIENCY BIDIRECTIONAL
ON-BOARD CHARGER
© Renault
Published on 19 January 2023.
• This more compact, high-efficiency charger will reduce energy losses by 30% and recharge the
vehicle’s battery faster.
• The bidirectional charger will also allow the connected vehicle to inject energy from the battery
into the electrical network.
• The subject of 11 patents, this unique French innovation will be deployed on Renault vehicles
by the end of the decade.
Jean-François Salessy, Vice-President Advanced
Engineering, Renault Group said:
“This project with the CEA has exceeded our expectations by confirming
the ability to achieve the expected performance in terms of efficiency
and compactness. It opens up strong prospects for power electronics,
which is a real challenge in the electric vehicle, in order to make the best
use of the batteries’ capacities. With bidirectional charging, the vehicle
serves the electrical network and enables the end consumer to reduce
energy costs.“
https://urlz.fr/nLQs
40
02 I SMART POWER DEVICES
SKIING MORE EFFICIENTLY THANKS
TO A FRENCH ALPS-BASED COLLABORATIVE INNOVATION
Published on 13 February 2023.
​Established by a consortium of stakeholders from the Auvergne-Rhône-Alpes region, the Smart Ski
Experience project explores a new connected ski technology that will offer snow sports enthusiasts an
unprecedented ski experience. Early experiments rely on an energy self-sufficient sensor placed on
skis, which will communicate with smartphones via Bluetooth in order to view a skier’s overall technical
control and level. It combines key parameters such as the skis’ impact in curves, frequency of execution
in turns, and speed. The project’s R&D budget is €1M, with 50% funding from the Auvergne-RhôneAlpes region, as part of its support to Public-Private partnerships in Innovation. It is supported by
Cluster Montagne.
© Louis Garnier
Philippe Watteau, CEA Director
of Technological Research Innovations, said:
https://urlz.fr/o4w4
“The Smart Ski Experience is a wonderful illustration
of the innovative capacity of YSPOT combined
with CEA reserach institutes. Our teams have
been supporting Rossignol to define new user
needs, develop technical evolutions arising from
market requirements, launch key local stakeholder
collaborations such as Lumiplan, and demonstrate
value propositions via field experiments. Together,
we are proud to be unveiling and offering the
unique Smart Ski Experience to all mountain lovers
gathered today in Courchevel!“
41
© id512 - Adobe Stock
SCIENTIFIC
REPORT
2023
42
03 I IMAGING, DISPLAYS AND SENSORS FOR SMART HUMAN ENVIRONMENT & MACHINE INTERACTION
IMAGING, DISPLAYS
AND SENSORS FOR SMART
HUMAN ENVIRONMENT &
MACHINE INTERACTION
Alexei Tchelnokov
© UtopikPhoto / CEA
Scientific Advisor to
the Optics and Photonics Division
CEA-Leti is active across the imaging
value chain, from sensor to display.
In 2023 we developed simulation
techniques for CZT detector R&D.
In infrared imaging, we continued
to drive advances in SWIR and
MWIR to bring our R&D partners
better size, weight, power, and
cost tradeoffs. Imagers for space
will benefit from new insights into
the origins of Random Telegraph
Signals in HgCdTe FPAs exposed to
proton irradiation. We also studied
nanostructured meta-optics for highenergy laser chains for sustainable
nuclear fusion and brought our
hardware and software expertise to
new signal processing approaches
for conventional Time-of-Flight (ToF)
histogram acquisition schemes.
43
SCIENTIFIC
REPORT
2023
Semiconductor development
to benefit from GPU-accelerated CZT
detector simulation
Guillaume Montémont
© E. Tolwinska - CEA
CEA-Leti research engineer
Simulation is an important tool in the development
of semiconductor devices like cadmium zinc telluride
(CZT) detectors, which, due to their excellent
properties, are ideally suited to medical imaging and
security applications—two areas where reliability
is crucial. And yet, the simulations used in the
development of these devices incorrectly assume that
the semiconductor material is flawless. CEA-Leti has
been working on more advanced simulation techniques
that would allow imperfections to be introduced,
making the simulations more realistic.
More realistic simulation for more reliable devices
Unlike simulated CZT detectors, real-world devices are far from
perfect. Structural defects that occur during the growth of the
substrate impact performance. What’s more, dynamic phenomena
like polarization degrade the estimation of incident photon energy
and position. Detector performance would be improved dramatically
if these defects could be accurately characterized and corrected for.
When it comes to simulation, this means developing a model that
can capture the complexities of non-uniform electric fields in the
detector and implementing a solution to the computational burden
this complexity creates.
A GPU-accelerated model that can handle non-uniformity
Impact
CEA-Leti made new advances in GPUaccelerated simulation that could result in
higher-performance CZT detectors.
Research partners
N/A
44
At CEA-Leti, we have been using graphics processing units (GPUs)
to parallelize the simulation of millions of photons and speed up the
calculations—vital to obtaining realistic simulations—with the goal of
developing a tool to analyze the impacts of real defects and calibrate
the detectors to correct for them.
New insights into defects for better-calibrated detectors
Our model accepts changes to the electric field, so that we can
rapidly observe changes in the detector’s behavior. In this research,
we introduced different types of spatial defects likely to be found in
real CZT crystals (point-like, planar, etc.), using the GPU-accelerated
simulation to quickly and easily visualize the impact of these defects
on the detector’s spatial and spectral response. By understanding
the specific nature and positioning of defects, they can be corrected
for. This will ultimately make the detectors more reliable.
03 I IMAGING, DISPLAYS AND SENSORS FOR SMART HUMAN ENVIRONMENT & MACHINE INTERACTION
© CEA
Top view of the area surrounding one pixel.
Color indicates the simulated intensity of the signal
measured by pixel as a function of incident photon
position. The impact of a higher conductivity region
is mainly seen as a reduction of signal intensity.
Further reading
• Delcourt, A., et al. GPU-accelerated CZT detector
simulation with charge build-up effects. Journal of
Instrumentation, 18, P02005, 2023.
45
SCIENTIFIC
REPORT
2023
ADVANCES IN
INFRARED IMAGING
When it comes to imaging technologies, the push for smaller pixel pitches is on,
bringing with it new obstacles to finding the best tradeoffs between size, weight,
power, and cost—all without sacrificing detection performance. CEA-Leti is driving
advances in short- and medium-wave infrared (SWIR and MWIR) imaging.
InGaAs is the legacy material for SWIR imaging. Developed
primarily for the security and defense market, the technology
is used in high-performance vision systems designed
for deployment in degraded environments. However, as
autonomous driving, industrial automation, and smart
agricultural systems take hold, higher-volume consumer
and commercial markets are driving new demand for SWIR
among CEA-Leti partners. These markets are hungry for
more affordable, compact, and powerful detectors. In terms
of R&D, this creates the challenge of how to shrink pixels
without negatively impacting performance.
In 2019, the CMOS imaging market leader disrupted SWIR
imaging with heterogeneous integration. By fabricating
InGaAs pixels on large silicon substrates, it became
possible to volume-manufacture the devices in CMOS
foundries at a low cost. The current state of the art in
InGaAs pixels on silicon read-out integrated circuits (ROIC)
is a 5 μm pitch (with greater than 75% quantum efficiency
46
CEA-Leti is investigating a new shallow-mesa architecture’s
potential for further reducing pixel pitch while achieving
state-of-the-art quantum efficiency and dark current
noise. The chosen fabrication process involved doping
the substrate in situ during epitaxy. The p/n junction was
created by etching the top p-type layer between the
pixels. However, unlike other mesa-type device fabrication
processes, CEA-Leti’s etching step only removes the
p-doped region from the top stack, resulting in a “shallow”
mesa. “This is a low-thermal-budget process that
bodes well for full integration in a
Si-CMOS-compatible fab. We also
fine-tuned the doping and thickness
of the barrier n-InP layer and the
doping concentration of the contact
layer, arriving at a set of doping
concentrations and thicknesses
that suppresses the barrier for
hole
collection. Passivation with a
Jacques Baylet
dielectric was carried out using two different processes
for comparison to see which one had the most impact
on dark current noise,” said CEA-Leti’s Jacques Baylet.
Schematic cross section of a
shallow-mesa-type photodiode.
© CEA
The race to smaller pixels and an optimal SWaP-C
tradeoff for SWIR detectors
at 1.2 μm and dark current noise reported as low as 2 nA/
cm2 at 0.1 V and 23 °C) in research conducted at Sony.
© UtopikPhoto / CEA
© UtopikPhoto / CEA
Infrared imaging “sees” what is invisible by giving us access
to electromagnetic information that the human eye cannot
detect. The potential applications
are vast. “Currently, silicon is the
material of choice for imaging in
the visible spectrum. However,
for wavelengths above 1 µm, the
material is transparent. Other
semiconductors are needed to
absorb infrared light and convert it
into
electrons to produce an image,”
Sebastien
said
CEA-Leti’s Sebastien Becker.
Becker
© Mariedofra - Adobe Stock
03 I IMAGING, DISPLAYS AND SENSORS FOR SMART HUMAN ENVIRONMENT & MACHINE INTERACTION
As MWIR detector pixels get smaller, CEA-Leti
strives to make them better
Further across the electromagnetic spectrum, HgCdTe
crystals (II-VI semiconductors) have historically been the
materials of choice for MWIR solutions for the defense
market. The need for longer-range vision systems is
the main driver of innovations in MWIR detectors, and
international competition to achieve smaller pixels and
greater performance is fierce. Today’s market is centered
around 15 µm pitch products, with 7.5 µm just over the
horizon. CEA-Leti and partner LYNRED have already
demonstrated the ability to industrially manufacture 7.5 µm
detectors.
CEA-Leti’s ambition is to shrink the pixel pitch to the
theoretical diffraction limit (5 µm) while pushing detection
performance beyond the state of the art in terms of
sensitivity, noise, and operating temperature. In 2023, we
continued to work with LYNRED with three objectives in
mind. The first was to demonstrate a viable technology to
manufacture IR detectors operating at 130 K or higher with
low pixel defectivity and high performance. The second
objective was to provide a shorter process flow than for the
previous technology. The final objective was to transfer the
technology to LYNRED for production.
The research will have a significant impact on LYNRED’s
future production of high-performance MWIR imaging
systems offering both high-resolution images and high
operating temperatures—a strong advantage over
competitors. “While the details of the
increase in image quality obtained
are confidential, they are enough
to be considered a game changer
in high-performance IR imaging
systems. The faster processing times
could also be a source of savings,
but this remains to be confirmed
once
production has begun,” said
Olivier
CEA-Leti’s
Olivier Gravrand.
Gravrand
© UtopikPhoto / CEA
The photodiodes were then tested and compared.
The measurement for 3 µm pixel pitch shallow mesa
photodiodes fabricated using this process is the first
published for such a small pitch. The dark current density
obtained was as low as 30 nA/cm2 for a 3 µm pixel pitch,
and as low as 5 nA/cm2 for a 5 µm pixel pitch at 0.1 V and
at room temperature. The reason for the increasing dark
current density at smaller pitches merits further study and
could provide further insights into how to improve the
performance of small-pitch photodiodes.
Further reading
• Baier, N., et al. Small pixel pitch MCT P on N MWIR photodiodes
at DEFIR: towards 7.5μm and beyond with very high image quality.
In Proceedings of Infrared Technology and Applications XLIX, SPIE,
Vol. 12534, 1253413. 2023. doi: 10.1117/12.2663760.
• Bustillos Vasco, S., et al. Modulation Transfer Function
Measurements by Electron-Beam-Induced Current of HgCdTe
Planar Diode with Small Pitch and High Operating Temperature.
Journal of Electronic Materials, 52, 7081–7088. 2023.
doi: 10.1007/s11664-023-10655-9.
• Rubaldo, L., et al. Sub-10μm pitch HOT technologies
development at Lynred. In Infrared Technology and Applications
XLIX, SPIE Proceedings Vol. 12534. 2023.
• Tillement, J., et al. Design and Characterization of 5 μm Pitch
InGaAs Photodiodes Using In Situ Doping and Shallow Mesa
Architecture for SWIR Sensing. Sensors, 23, 9219. 2023.
doi: 10.3390/s23229219.
47
SCIENTIFIC
REPORT
2023
New analysis capabilities could
help make future infrared
detectors more robust
Nicolas Baier
© UtopikPhoto / CEA
CEA-Leti research
engineer
Over their lifetimes, satellites in orbit are subjected
to harsh radiation from the sun. On Earth, it is
difficult to test how much scientific payloads
like infrared detectors will degrade over time in
orbit due to exposure to this radiation, except in
advanced research facilities. CEA-Leti was able
to gain new insights into the impacts of radiation
on detector performance that will help extend
the lifetimes of infrared images on board future
satellites.
Assessing the durability of low-temperature HgCdTe
infrared detectors in space
Impact
The ability to more effectively verify the
robustness of new designs will be vital
to research partner Airbus Defence and
Space in developing solutions to extend
the lifetime of infrared imagers in space.
Research partners
ISAE-SUPAERO, Airbus Defence
and Space.
48
The purpose of this research was to gain a deeper understanding
of the performance and degradation of low-temperature
HgCdTe infrared detectors, instruments that are often included
in scientific payloads, when exposed to the kind of radiation
experienced in orbit—and that is virtually non-existent on Earth.
Special instruments like proton accelerators and gamma sources
are required to replicate these particularly harsh conditions in a
controlled setting.
Random telegraph signals in the crosshairs
The strategy employed in CEA-Leti’s research was to expose
the components to radiation over several irradiation sequences
to simulate the detector’s state at various stages in its lifecycle.
The idea was to zoom in on a particular kind of radiation-induced
noise known as random telegraph signals. The affected pixels may
intermittently display normal behavior, which makes the problem
hard to detect. By tracking the increase in affected pixels and
studying their properties and dynamics over time, we were able to
get a clear picture of the impact on detector performance.
03 I IMAGING, DISPLAYS AND SENSORS FOR SMART HUMAN ENVIRONMENT & MACHINE INTERACTION
“Rest” could help damaged pixels recover
During
irradiation
After
irradiation
© CE A
© CEA
Exposure to radiation during operation creates
defects in infrared detectors. Some of these
are immediately obvious, but others are only
revealed once the detector heats back up to
ambient temperature. Not knowing whether a
detector has latent defects that will manifest
themselves during the detector’s lifetime is a real
problem. We observed that heating the detector
up to a temperature slightly higher than ambient
temperature (less than 100°C) can “heal” some of the
defects, and those remaining tend to shift towards
less impactful configurations. Unfortunately, this
annealed is not possible in space.
Before
irradiation
Ségolène
Dinand
CEA-Leti PhD student
Ségolène Dinand, who
authored an article in IEEE
Transactions on Nuclear
Science about the research,
also won a William E. Spicer
- Thomas N. Casselman
Best Student Paper Award
at the U.S. Workshop on the
Physics and Chemistry of II-VI
Materials (II-VI Workshop) for
this research.
Birth of an RTS behavior in one pixel
after a strong event during irradiation
Further reading
• Dinand, S., et al. Proton Radiation-Induced Random
Telegraph Signal in HgCdTe Photodiode Array. IEEE
Transactions on Nuclear Science, 70(8). 2023.
49
SCIENTIFIC
REPORT
2023
Pierre Brianceau
Meta-optics for inertial
confinement fusion
laser facilities
Jérôme Neauport
Research institutes around the world are investigating
high-energy laser chains as a path toward nuclear
fusion. While the ability to obtain nuclear fusion
reactions with a net energy gain was demonstrated
at a US Department of Energy Lab in 2022, several
challenges must still be overcome. One of them is the
occurrence of optical-component-damaging nonlinear
Kerr effects at high laser intensities. A recent advance
by CEA-Leti and partners could help change that.
© UtopikPhoto / CEA
CEA-Leti research
engineer
© CEA-Cesta
CEA-Cesta research
engineer
Nicolas Bonod
CNRS-Institut Fresnel
research engineer
© CNRS
Silica optics subject to damage under high-power lasers
Impact
Nanostructured metasurfaces were
implemented in novel silica waveplates
capable of withstanding high laser
fluence. The meta-optic successfully
delayed the Kerr effect and could
potentially also be used to manipulate
polarization for optical smoothing to limit
instability during laser-target interaction.
Research partners
CEA-CESTA, Institut Fresnel (CNRS, AMU,
Centrale Marseille)
50
While the advance at the National Ignition Facility (NIF) in the US
made headlines in 2022, France also has its own powerful laser-based
inertial confinement fusion facility, the Megajoule Laser (LMJ) near
Bordeaux. This facility will have 176 beams delivering linearly-polarized
nanosecond laser pulses, which, after amplification in the near-infrared
and frequency tripling to reach a wavelength of 351 nm, pass through
transparent silica optics and converge on a target located at the center
of a large spherical chamber. This is where the Kerr effect comes in,
potentially causing the beams to self-focus in the silica. For high-power
lasers like the ones at NIF and LMJ, this self-focusing phenomenon can
create multiple filaments, damaging the silica optics. This presents a
potential obstacle to increasing the power of these lasers.
A new approach to converting linear polarization to circular
The Kerr effect depends on the polarization of the laser beam and can
be mitigated by circular polarization. Linear-to-circular polarization
conversion can be obtained using a quarter-wave plate. The problem
is that the anisotropic materials used to make quarter-wave plates
would be damaged by such powerful lasers. So, an alternative
approach to effectively manipulating the beams was needed.
Amorphous silica is compatible with high-power laser beams but does
not affect polarization in its usual form. This is not the case, however,
when the material is nanostructured.
© CEA
03 I IMAGING, DISPLAYS AND SENSORS FOR SMART HUMAN ENVIRONMENT & MACHINE INTERACTION
Nanostructured silica for
quarter-wave plate application.
Metamaterial tames laser filamentation
To make the new quarter-wave plate, the amorphous
silica was structured with deep and closely spaced linear
grooves to obtain the required specifications: a period
smaller than the laser wavelength, a substantial aspect
ratio, minimal phase delay with high transmittance, and
the ability to withstand laser fluence. The nanostructured
meta-optics successfully controlled filamentation in glass
under circular polarization—a breakthrough.
Further reading
• Bonod, N., et al. Linear-to-Circular Polarization
Conversion with Full-Silica Meta-Optics to Reduce
Nonlinear Effects in High-Energy Lasers. Nature
Communications, 14, 5383, 2023,
doi : 10.1038/s41467-023-40709-9.
• Bonod, N., et al. Full-Silica Metamaterial Wave Plate
for High-Intensity
UV Lasers. Optica, 8, 1372-1379, 2021,
doi: 10.1364/OPTICA.434662.
Collaboration between partners instrumental
These results would not have been possible without
exemplary collaboration between CEA-Leti and its
partners. CEA-CESTA and CNRS-Institut Fresnel
came up with the idea and designed the experiment;
CEA-CESTA analyzed and supervised the optical
metrology and performed laser damage experiments;
Institut Fresnel performed the numerical modeling; and
CEA-Leti developed and executed the half-scale sample
fabrication process. Scaling this technology to full-sized
optical components presents an exciting challenge
with enormous potential benefits for high-energy laser
facilities and, ultimately, sustainable nuclear fusion.
51
SCIENTIFIC
REPORT
2023
Algorithm-architecture co-design for compact
representation of ToF pixel data
William Guicquero
© UtopikPhoto / CEA
CEA-Leti research
engineer
CEA-Leti combined its hardware
and software expertise to
investigate the benefits of new
signal processing approaches to
conventional Time-of-Flight (ToF)
histogram acquisition schemes.
Among the techniques developed
are compressive sensing and
expectation-maximization
algorithms. Both turned out to be
promising avenues for reducing
hardware design constraints in
active direct ToF 3D imaging based
on SPAD pixels.
Direct time-of-flight for active 3D imaging
Direct time-of-flight (D-ToF) imagers, which detect the time-of-arrival
of reflected light pulses from a synchronized laser, are one of the key
enablers for active 3D imaging, which has a wide range of applications
from manufacturing to defense. A device called a single photon
avalanche diode (SPAD), which is affordable, low-noise, and effective,
is generally used to detect the photons’ arrival. Finally, a histogram of
ToF data is generated using a technique called time correlated single
photon counting (TCSPC). Several challenges—background noise,
bulky in-pixel circuits, and large volumes of data—must be overcome
to make the combined use of TCSPC and SPAD a viable solution.
From photons in the wild to meaningful
data, a study of TCSPC physical models
and processing variants.
These innovations represent significant
strides in the field of depth sensing,
offering promising avenues for future
research and development. By addressing
the inherent challenges in SPAD sensors
and TCSPC histograms, we have laid the
groundwork for more efficient, accurate,
and versatile depth-sensing technologies
based on D-ToF active 3D imaging.
Research partners
N/A
52
© CEA
Impact
Overcoming the challenges of TCSPC and SPAD
To address the issues preventing the widespread adoption of TCSPC
and SPAD for 3D imaging, our first objective was to thoroughly review
all working modes for TCSPC, utilizing a physically-plausible SPAD
sensor model. Secondly, we explored alternatives to the conventional
ToF histogram acquisition scheme, focusing on compressive sensing
(CS), which is data-agnostic by design, and expectation-maximization
(EM), which is intrinsically data-driven. The idea was to arrive at a
balanced view of the advantages and potential drawbacks of both
techniques and their capacity to enable concrete and practical sensors
design with improved characteristics. Finally, we also investigated the
application of today’s deep learning models for depth map rendering.
© 3d_kot - Adobe Stock
03 I IMAGING, DISPLAYS AND SENSORS FOR SMART HUMAN ENVIRONMENT & MACHINE INTERACTION
Findings promising for tomorrow’s depth sensing
technologies
We established that ToF histograms from high photon
counts in synchronous modes could be accurately
modeled using a mixture of truncated-shifted Erlang
distributions. A customized EM algorithm was
proposed for precise pixel parameter estimation. A
novel 2-stage online EM algorithm was developed
for efficient peak detection, coupled with a pixellevel hardware implementation. This approach
demonstrated a substantial compression ratio of 0.4%
and a 40% reduction in pixel pitch, all without sacrificing
performance. A pixel-wise CS approach was also
designed, with its hardware implementation. Beyond
showcasing the effectiveness of information retrieval
via a LASSO type of algorithm and enabling a practical
pixel pitch reduction, the CS data can also feed deep
generative models (DGM) for reconstruction.
Further reading
• Poisson, V., et al. Deep learning depth-intensity
reconstruction from compressive TCSPC SPADbased imaging, 2023.
• Poisson, V., et al. TCSPC histogram data modeling:
A custom EM algorithm dedicated to a mixture of
truncated-shifted Erlangs, 2023.
• Poisson, V., et al. A 2-Stage EM Algorithm for
Online Peak Detection, an Application to TCSPC
Data. IEEE Transactions on Circuits and Systems II:
Express Briefs, 69(9), 3625-3629, 2022,
doi: 10.1109/TCSII.2022.3181687.
• Poisson, V., et al. Histogram Compressive Sensing
using Shuffled Cellular Automata: the TCSPC
sensor use case. In Proceedings of the 20th IEEE
Interregional NEWCAS Conference (NEWCAS) (pp.
124-128), Quebec City, QC, Canada, 2022,
doi: 10.1109/NEWCAS52662.2022.9842077.
• Poisson, V., et al. Luminance-Depth Reconstruction
From Compressed Time-of-Flight Histograms. IEEE
Transactions on Computational Imaging, 8, 148-161,
2022, doi: 10.1109/TCI.2022.3149088.
53
SCIENTIFIC
REPORT
2023
MARKET
NEWS
FROM OUR R&D PARTNERS
INFRARED VISION:
EXCEPTIONALLY
SHARP IMAGES
Published on 25 April 2023.
​The CEA-Leti transfer of technology to LYNRED
provides a set of technological building blocks for
cooled infrared detectors with record-breaking
performance. These new detectors can operate
at 130 kelvin or more using a novel 7.5 µm pixel
architecture with high resolution and exceptionally
sharp images. These detectors are aimed at the
defense sector, but may also be of interest for
astrophysics and weather forecasting.
Olivier Gravrand, research director at CEA-Leti said:
“We devised a new method for measuring MTF sharpness.
Instead of injecting photons locally to excite the pixels, we use
a scanning electron microscope to inject electrons. This ‘electron
brush’ is much finer than the conventional optical beam and
allows for a more accurate measurement of MTF.“
https://urlz.fr/nKDb
Source : ELECTRONIQUES N° 142. Jan.- Feb. 2023.
This young company, based near Grenoble, is developing
self-powered sensors to monitor room parameters
and optimize energy consumption.
https://urlz.fr/o2uq
www.orioma.com
54
© sutichak - Fotolia
ORIOMA USES INFRARED
TO REDUCE ENERGY BILLS
IN BUILDINGS
© ImageFlow / IRStone - Adobe Stock
03 I IMAGING, DISPLAYS AND SENSORS FOR SMART HUMAN ENVIRONMENT & MACHINE INTERACTION
Source: ViPress.net
Published by Pascal Coutance. Mar 2, 2023.
By reducing the spacing between each carrier frequency
to just 100 GHz, the multifrequency laser source integrated
on a silicon chip, which Scintil Photonics will be presenting at
OFC 2023, makes it possible to increase the number of optical
fiber transmission channels in high-performance computing
and artificial intelligence applications.
© Scintil Photonics
GRENOBLE-BASED SCINTIL PHOTONICS UNVEILS A WORLDFIRST SILICON-INTEGRATED MULTIFREQUENCY LASER
https://urlz.fr/nMVM
www.scintil-photonics.com
© Microoled
MICROOLED RAISES
€21 MILLION
The start-up from CEA-Leti is
specialized in the design, production
and marketing of OLED microdisplays
for near-eye applications.
In just a few years, Microoled has
become a key partner of the world’s
top technology integrators with a
unique technology that combines high
resolution, high levels of brightness
and low energy consumption.
https://urlz.fr/nJM2
www.microoled.net
55
© jamesteohart - Adobe Stock
SCIENTIFIC
REPORT
2023
56
04 I TELECOMUNICATION AND SECURITY FOR CONNECTED SOCIETY
TELECOMUNICATION
AND SECURITY FOR
CONNECTED SOCIETY
Viviane Cattin
© DR CEA / M. Jary
Scientific Advisor to the Smart Devices,
Telecommunications and Security Division
Technology and society are
throughlines of CEA-Leti’s
telecommunications research. 2023
saw innovation in advanced RF and
optical communication circuits,
and in intelligent and collaborative
network infrastructures. We
also made decisive progress on
propagation, with better-controlled
compact antennas and radiationsensitive surfaces. We investigated
a low-power mmW on-chip radar
transceiver and a low-power RF
receiver architecture for industrial,
scientific, and medical monitoring.
And, with trust in digital technology
a more pressing concern than
ever, we studied component
vulnerabilities and secure hardware,
including AI-based embedded
systems for IoT.
57
SCIENTIFIC
REPORT
2023
THE 5G TO 6G TIPPING
POINT HAS ARRIVED
With mobile traffic doubling over the past two years and R&D ecosystems
poised to support the next steps in network deployment thanks in part to
an influx of government funding, 2023 stands as a year of transition from
5G to the transformative era of 6G. CEA-Leti is at the forefront of network
R&D against a particularly dynamic market and policy backdrop.
•
•
•
•
58
Co-coordinator of French PEPR
(Priority Research Facilities and
Programs) in electronics and
future networks
Associated participant in IPCEI
ME/CT (Important Project of
Common European Interest
in microelectronics and
communication technologies)
Involved in 5+ ANR (French
National Research Agency)
projects
Involved in 10+ EU-funded
projects
© Chr. Morel / CEA
CEA-Leti a stakeholder
in national and European
research initiatives:
CEA-Leti is anticipating a surge in demand
for innovation in all wireless communication
technologies and is banking on strong
partnerships with maturing ecosystems to
deliver them. “We believe that our research
must support a sustainable, sovereign, and
just transition from 5G to 6G. Our academic
and
other partners and our involvement in
Jean-Baptiste
Doré
French and EU initiatives to galvanize the
research community around tomorrow’s networks put us in a
position of collective strength to tackle the challenges ahead,”
said CEA-Leti’s Jean-Baptiste Doré.
The first technological benchmarks for 6G are emerging. And, as
the 2030 milestone approaches, CEA-Leti’s research will continue to
catalyze high-performance devices that will make today’s promising
concepts realities for tomorrow’s networks. In 2023, we made
strides in GaN-on-silicon semiconductor devices, RF architectures
and antenna systems, optical communications, and AI-enabled
signal processing and network orchestration.
© Cris.lo Studio - Adobe Stock
04 I TELECOMUNICATION AND SECURITY FOR CONNECTED SOCIETY
The transition from 5G to 6G
telecommunications is placing new demands—
frequency, power, efficiency, compactness—
on radio frequency (RF) amplifiers. The key to
meet these demands will be high-performance
transistors made from advanced semiconductor
materials.
Overcoming cost and scalability challenges to 6G
Record RF power levels and efficiencies at high frequencies
have already been demonstrated on gallium nitride (GaN)
high electron mobility transistors (HEMTs). The current
issue with GaN HEMTs is that they must be fabricated on
silicon carbide (SiC) in special cleanrooms. In addition,
the high-performance SiC used to grow the GaN layers is
expensive and only available in smaller wafer sizes. Pivoting
to GaN/Si devices fabricated on larger wafers using
high-performance CMOS processes in today’s standard
cleanrooms would go a long way toward reducing costs.
capabilities. We used the most advanced ultra-wide
bandgap material available (AlN), an advanced surface
passivation technique, and a metal insulator semiconductor
(MIS) gate architecture. Because the heterojunction layer is
highly sensitive to virtually every fabrication process step,
we used soft processing during etching and deposition
and kept the thermal budget low to preserve processability
and performance. An additional challenge was achieving
the desired performance at around 30 GHz. Here, we
developed a short gate technology (with a 150 nm gate
length) with uniform on-wafer characteristics. Several
CEA-Leti labs and partner STMicroelectronics helped
develop and fine-tune this original transistor process flow,
contributing expertise in deposition, etching, and CMP.
“We developed an original low-cost, efficient GaN
MIS-HEMT technology that will be
used by designers to build lightweight,
compact, high-performance power
amplifiers for 5G-6G, satellite
communications, civil and defense
radars and jammers, and earth
observation equipment,” said CEA-Leti
engineer Erwan Morvan.
© CEA
Advances in GaN on silicon
for cost-effective highperformance RF amplifiers
Erwan Morvan
Rebuilding GaN/Si technology to compete with
expensive GaN/SiC
We took the entire fabrication process apart and put it
back together to take full advantage of CMOS cleanroom
59
Organic micro-OLEDs enable
ultra-high-data-rate optical
wireless transmission
Visible light communication (VLC), which
operates in the unlicensed optical spectrum,
could effectively round out radio frequency
(RF) communication and alleviate RF
network congestion for effective end-to-end
communication. The research community has
been hard at work trying to exploit VLC’s vast
potential for improvement at both the material
and device levels. CEA-Leti has thrown its
micro-OLEDs into the ring, hoping to bring
the devices’ low fabrication cost, minimal
carbon footprint, and ease of hybridization on
any substrate to the world of optical wireless
communications.
Partnerships play a key role in setting new optical
transmission record
Alexis Fischer
“Our co-supervised PhD has produced state-of-the-art
results, and we are expecting additional publications
and a patent,” said Professor Alexis Fischer of
Université Sorbonne Paris Nord (USPN). “But beyond
that, our partnership with CEA-Leti is exemplary in several
respects. First, it is balanced. Each party freely shares the
knowledge that can be shared. And, while we do have
our own cleanrooms, it is wonderful to have access to
CEA-Leti’s advanced equipment and the know-how of not
one, but two of its labs. We are highly complementary,
covering OLED research from material science, to optics,
to information technology. I don’t know many research
organizations capable of getting several labs, internal and
external, working together in synergy to achieve scientific
advances as quickly as CEA-Leti can,” Fischer said.
Toward more sustainable optical wireless devices
Recent developments in optoelectronics have focused
on crystalline inorganic semiconductors. While their
performance is excellent, their environmental impacts are
substantial. Organic LEDs offer a more environmentallyattractive alternative, and, if this breakthrough is any
measure, a viable one in terms of performance.
60
© CEA
© UtopikPhoto / CEA
This research produced the fastest micro-OLED ever
fabricated, with an active area of 40x40µm² and an observed
cutoff frequency of up to 459 MHz. We also reported a
world-first multi-gigabit transmission (2.85 Gb/s). “These
results would not have been possible without French
(the ANR DEµS project) and EU (Important Project of
Common European Interest in microelectronics and
communication technologies) research initiatives.
Together with our partners we
were able to develop a high-end
transmission setup for optical microsources, integrate and characterize
them, and, finally, optimize the
digital waveform transmitted.
These new benchmarks will enable
and encourage the development
of complete organic systems,
Luc Maret
with organic optical emitters and
receivers,” said CEA-Leti engineer Luc Maret. A CEA-Leti
PhD student, Mohamed Nihal Munshi, was first author on
two papers about the research published in the journals
Organic Electronics and IEEE Photonics Technology Letters.
© Université Sorbonne Paris Nord
SCIENTIFIC
REPORT
2023
Data rate function of separation distance,
compared to previous works (inset: bit
error rate function of data rate).
04 I TELECOMUNICATION AND SECURITY FOR CONNECTED SOCIETY
AI-driven efficiency will
transform next-gen
communication networks
Drastic improvements in artificial intelligence
are blazing trails into an array of use cases—
including wireless communications. CEA-Leti
is helping create AI-enabled networks with
pioneering cooperative orchestration and
distributed learning techniques that could
revolutionize radio resource management in
mission-critical networks.
Self-configuring drone swarms for flexible, ondemand network coverage, anywhere
Forest fires—a threat to people, property, and biodiversity—
are on the rise. In remote areas with limited cellular
coverage, AI could enable innovative solutions. Imagine
an AI-enabled fleet of drones capable of communicating
with each other and with a ground control center to
autonomously configure a temporary 3D network to provide
real-time data processing and communication support for
firefighting efforts. Although a drone-swarm-network might
seem futuristic at first glance, it is a realistic solution if it can
be made cost effective and energy efficient.
Joint optimization of available radio, computing,
storage, and energy resources
© UtopikPhoto / CEA
CEA-Leti is developing AI-based communication protocols
and orchestration mechanisms to enable the kind of
autonomous and self-configuring network described in the
forest fire scenario. “The challenge is to make the best
use of all resources in a dynamic network characterized
by relatively high mobility, fluctuating traffic demand,
and an evolving network topology, for networks with
low computational complexity and energy consumption.
We proposed using multi-agent
reinforcement learning (MARL)
for autonomous decision-making
by mobile access points (MAPs),”
said CEA-Leti engineer Mohamed
Sana. The AI-endowed MAPs (the
drones) autonomously cooperated
to maximize network coverage and
capacity
in real time, aided by a dual
Mohamed Sana
neural attention architecture for on-the-fly communication
protocol adjustments. Backhaul limitations were addressed
by a two-level hierarchical resource allocation mechanism
to enable on-demand backhaul and access capacity,
significantly improving network performance.
The best tradeoff between flexibility, cost, and
complexity over the network lifespan
To further make learned protocols more robust and reduce
their computational complexity, we wanted to ensure that
knowledge acquired in specific scenarios could be applied
to distinct unseen scenarios without requiring additional
© CEA
An heterogeneous 3D
network deployment with
radio and computing
resources.
learning. Our federated MARL framework consolidated
multiple learned protocols into a “meta protocol” for the
3D operation of a 5G network with a fluctuating number of
MAPs, for an encouraging tradeoff between management
flexibility, operating cost, and complexity over the network
lifespan. However, in practical use cases, hardware and/or
energy constraints may limit the deployment and execution
of learned protocols on each MAP. To overcome this
limitation, we adopted a newly-introduced concept called
deep neural network (DNN) splitting and proposed an online
adaptive resource allocation algorithm to jointly optimize
radio and computing resources for the best tradeoff
between energy consumption, latency, and accuracy.
What’s next in the wireless communication revolution
CEA-Leti’s AI-driven solutions are helping enable
new levels of network efficiency, optimizing energy
consumption and computational and operational
complexity. With groundbreaking network paradigms
just over the horizon, our research is setting the stage for
smarter, more sustainable connectivity.
Further reading
• Morvan, E., et al. 6.6W/mm 200mm CMOS compatible AlN/
GaN/Si MIS-HEMT with in-situ SiN gate dielectric and low
temperature ohmic contacts. Paper presented at the IEDM
Conference, San Francisco. 2023.
• Munshi, M. N., et al. High-speed OLED bandwidth
optimization method based on Relative Intensity Noise
measurements. Organic Electronics, 123, 106935. ISSN 1566
1199. 2023. doi: 10.1016/j.orgel.2023.106935.
• Munshi, M. N., et al. 2.85-Gb/s Organic Light Communication
With a 459-MHz Micro-OLED. IEEE Photonics Technology
Letters, 35(24), 1399-1402. 2023. doi: 10.1109/LPT.2023.3327612.
• Sana, M., “Distributed Learning for 5G and Beyond Network
Management and Orchestration,” phdthesis, Université
Grenoble Alpes [2020-....], 2021. Accessed: Aug. 25, 2023.
[Online]. Available: https://theses.hal.science/tel-04086284.
• Catté, E., et al., “Dual-Attention Deep Reinforcement
Learning for Multi-MAP 3D Trajectory Optimization in
Dynamic 5G Networks.” arXiv, Mar. 14, 2023. doi: 10.48550/
arXiv.2303.05233. (accepted for publication in IEEE ICC 2023).
• Laurent, J., et al., “Hardware Architecture of a Beam
Alignment Module for D-band Fronthaul and Backhaul,” in
ICC 2023 - IEEE International Conference on Communications,
(accepted for publication in IEEE ICC 2023).
• Sana, M., et al., Learning Hierarchical Resource Allocation and
Multi-agent Coordination of 5G mobile IAB Nodes. 2023. doi:
10.48550/arXiv.2302.07573. (accepted for publication in IEEE
ICC 2023).
• Catté, E., et al., “Federated Multi-Agent Deep Reinforcement
Learning for Dynamic and Flexible 3D Operation of 5G MultiMAP Networks.” arXiv, Jun. 30, 2023. Accessed: Aug. 25, 2023.
[Online]. Available: http://arxiv.org/abs/2307.06842(accepted for
publication in IEEE PIMRC 2023).
• I. Labriji, M. et al. “Energy-efficient cooperative inference via
adaptive deep neural network splitting at the edge,” Feb. 24, 2023.
doi: 10.1234/ICC. (accepted for publication in IEEE ICC 2023).
61
SCIENTIFIC
REPORT
2023
Smart antennas: manipulating,
shaping, and controlling electromagnetic
waves for telecommunications,
localization, and sensing
Christophe
Delaveaud
© CEA
CEA-Leti Research
Director
Impact
These advances resulted in new design
and optimization tools for compact
supergain antennas and near- and farfield transmitarray antennas, as well as
new metrics and models for the study of
wave propagation.
Last year was a fruitful one for antenna
and propagation research at CEA-Leti, with
advances in the characterization of wave
propagation, the development of innovative
beam shaping solutions for millimeter wave
antennas, and a deeper understanding
of directivity and efficiency in miniature
antennas.
New understanding of stationary distance could improve
system performance
Our characterization and modeling work led to a new
understanding of the propagation of millimeter waves. A channel
sounder was developed and experiments carried out to study
channel correlation properties and quasi-stationary time. Using
different metrics, we looked at how to meaningfully determine
stationary distance, a factor that has a huge influence on channel
properties and overall system performance.
Research partners
CNES, DGA, IEMN, IETR, Oviedo University,
Radiall, Université Paris-Sorbonne, UCL.
Joseph Hoellinger
• Hoellinger, J., et al. Channel Correlation and
Stationarity in mm-Wave V2V Channels. In 2023
17th European Conference on Antennas and
Propagation (EuCAP) (pp. 1-5). Florence, Italy. 2023.
doi: 10.23919/EuCAP57121.2023.10133740.
• Koutsos, O., et al. Wideband Transmitarrays based
on Anisotropic Unit-Cells for Next Generation
sub-THz Applications. In 2023 17th European
Conference on Antennas and Propagation (EuCAP)
(pp. 1-5). Florence, Italy. 2023. doi: 10.23919/
EuCAP57121.2023.10133333.
• Munoz, F., et al. Space-Time Dense Multipath
Components Modeling at mmWaves in Indoor
Industrial Environments. In 2023 17th European
Conference on Antennas and Propagation (EuCAP)
(pp. 1-5). Florence, Italy. 2023. doi: 10.23919/
EuCAP57121.2023.10133474.
• Tornese, A., et al. Compact End-Fire Arrays: from
Theory to Directivity and Gain Maximization. In
2023 17th European Conference on Antennas and
Propagation (EuCAP) (pp. 1-5). Florence, Italy. 2023.
doi: 10.23919/EuCAP57121.2023.10133075.
62
© CE A
Further reading
CEA-Leti PhD student
Joseph Hoellinger won
a Best Paper Award for
this research.
Controlling beam shaping in millimeter-wave antennas
We also investigated reconfigurable transmitarrays in the Ka-band
for satellite communications and, especially, “satcom-on-the-move”
systems. These systems need high-gain, wide beam-scanning, and
circular polarization switching capabilities. We studied two unit-cell
architectures, integrating them into two transmitarray prototypes.
In the first architecture, polarization switching is implemented by
V- and H-polarized cells. In the second, a polarization converter
is used. The second outperformed the first in terms of aperture
efficiency, at 24.8% compared to 18%.
© CEA
04 I TELECOMUNICATION AND SECURITY FOR CONNECTED SOCIETY
CEA-Leti’s anechoid room.
Pushing back the fundamental limits of miniature antennas
Finally, we studied directivity and gain properties in different
compact antenna architectures. We used a loss model integrated
into the optimization tool to optimize Huygens source end-fire
arrays according to two strategies maximizing either directivity or
gain. Losses due to the miniaturization of the radiating source and
coupling had a major impact on radiation performance, especially
for the Huygens source array. However, we did demonstrate an
efficiency gain of up to 8 dBi for gain optimization (vs. directivity
optimization) for small dipole end-fire arrays.
63
SCIENTIFIC
REPORT
2023
Ultra-low-power filter for RF spectrum
sensing could lead to more energyefficient “listening” on IoT networks
Dominique Morche
The wireless radio chips used in IoT
systems spend much of their time
idly waiting for a communication
request to come in. This passive
“listening” wastes enormous
amounts of energy. CEA-Leti
helped develop an ultra-low-power
“listening” chip that could solve
this problem.
Impact
Our new receiver architecture obtained
the best-ever figure of merit for such a
low-pass filter. This advance will help
reduce the power consumption of IoT
devices.
Research partners
École Polytechnique Fédérale
de Lausanne (EPFL).
Further reading
• Pekcokguler, N., et al. An Ultra-Low-Power
Widely-Tunable Complex Band-Pass Filter for RF
Spectrum Sensing. IEEE Transactions on Circuits
and Systems I: Regular Papers, 70(10), 3879-3887,
2023, doi: 10.1109/TCSI.2023.3300965.
64
© Syda Productions - Adobe Stock
© CEA
CEA-Leti engineer
A new chip and a novel spectrum-scanning strategy
Our objective was to develop a new radio chip tasked exclusively
with listening for communication requests from the network. We
worked with EPFL as part of a co-supervised PhD research project to
completely overhaul the receiver architecture, introducing tunable
complex filtering to scan the entire the 2.4GHz Industrial, Scientific,
and Medical (ISM) band without modifying the oscillating frequency.
The result is much faster scanning that uses much less energy.
Power-to-performance ratio better than the state of the art
for this type of device
The 0.0049 mm2, widely-tunable first-order ultra-low-power
transconductor-capacitor CBPF (complex band-pass filter) was
fabricated using the GlobalFoundries® 22FDX® 22 nm FD-SOI process
platform. We were able to obtain a frequency shift of ±60 MHz in the
5 MHz to 40 MHz bandwidth range. Power consumption ranged
from 6.7 µW to 99.2 µW with the best and worst figure of merit (the
power-to-performance ratio) being 0.034 fJ/pole and 0.082 fJ/pole.
The implications of our work extend beyond power savings,
and could enable innovative spectrum sensing algorithms, ultralow-power location, and more efficient network security solutions,
for example. Reducing power consumption is a major bottleneck
to the development of IoT services, and our research will help remove
this barrier to more energy-efficient connectivity.
04 I TELECOMUNICATION AND SECURITY FOR CONNECTED SOCIETY
Record mmW radar performance
to support remote contactless
vital sign detection
Mykhailo Zarudniev
© CEA
CEA-Leti engineer
CEA-Leti developed a new radar technology that could enable low-power,
high-performance on-chip radar transceivers for the contactless measurement
of vital signs for automotive in-cabin systems and medical devices. The
technology is sensitive enough to generate a human heartbeat profile from
surface micro-vibrations of the thorax.
Meeting the requirements of demanding markets
The markets for non-invasive vital sign monitoring
are expanding into new territory. Medical device
manufacturers are no longer the only companies
interested in integrated radar-on-chip transceivers. The
automotive industry is also on the lookout for in-cabin
solutions to detect forgotten babies and pets and monitor
driver and passenger health. Whatever the market, the
devices and their antennas must be very compact and
lightweight while delivering extreme ranging precision,
high spatio-temporal resolution, and low mean power
consumption.
demonstration of ranging sensitivity confirmed 10 µm
sensitivity in the range direction at sensor rates up to
100 kHz—on par with an echocardiograph—even in the
presence of significant mechanical disturbances, like those
present around a person riding in a car or running on a
treadmill. Parasitic movements can be digitally filtered out,
leaving clear, accurate vital sign readings.
New architecture and original frequency
multiplication technique yield excellent results
Unparalleled chirp modulation for extremely
sensitive radar sensing
We obtained chirp modulation rates as high as 30 GHz/
µs on a 60 GHz carrier, with exceptional phase noise
performance. This is the steepest chirp slope known for
mmW radar systems to date. The low-frequency input
enables the use of a direct digital synthesizer to perform
fast chirping on mmW frequencies. Our application-level
© CEA
The main objective of this research was to validate
the operation of a new radar transceiver architecture
capable of delivering low phase noise, fast chirp signal
generation, and low operational duty cycles. In terms
of precision, our benchmark was based on conventional
echocardiography, which meant being able to measure
object displacements of 10 µm at a repetition rate of
around 1 kHz. The main integrated circuit design obstacle
was to achieve operation in the 60 GHz band with low
power and low phase noise starting from a 2 GHz carrier
signal. Traditionally, 10 GHz signals are converted to
mmW frequencies to do this. Here, we introduced an
innovative mmW FMCW radar signal generation technique
utilizing a periodically repeated oscillation train (PROT)
and injection-locked oscillators (ILO), enabling frequency
multiplication rates exceeding 30X from low-frequency
synthesizers.
PCB based demonstator with 60 GHz
45 nm RF-SOI radar transceiver.
Impact
This low-power mmW radar transceiver technology
could pave the way towards new solutions in structural
health monitoring, instrumented sports equipment,
automotive in-cabin monitoring, and human health
monitoring.
Research partners
N/A
Further reading
• Siligaris, A., et al. Fast Chirping 58-64 GHz FMCW
Radar Transceiver using D-PROT Multiplier in CMOS
45nm RFSOI for Vital Signs Detection. In ESSCIRC
2023 Conference Proceedings (pp. 505-508). 2023..
65
SCIENTIFIC
REPORT
2023
AI-enabled power amplification could
help make wireless communications
more energy efficient
© Chr. Morel / CEA
CEA-Leti 6G Program
Manager
Artificial intelligence is ushering
in a new era of digital wireless
communication systems R&D.
CEA-Leti is pioneering advances
in this exciting field to lay the
groundwork for 5G-and-beyond
solutions with unprecedented
energy efficiency. A recent
investigation of neural networks
and meta-learning for digital predistortion of power amplification
yielded encouraging results.
Impact
This transformative innovation
significantly reduces complexity and
data consumption, bringing new levels
of efficiency and adaptability to DPD
for PAs. The power of AI will make
tomorrow’s wireless communications
networks smarter and more energyefficient.
Research partners
N/A
Further reading
• Falempin, A., et al. Low-Complexity
Adaptive Digital Pre-Distortion with MetaLearning based Neural Networks. In 2022 IEEE
19th Annual Consumer Communications &
Networking Conference (CCNC) (pp. 453-453).
Las Vegas, NV, USA, 2022. doi: 10.1109/
CCNC49033.2022.9700529.
• Falempin, A., et al. Low-Complexity
Adaptive DPD: From Online Optimization
to Meta-Learning. IEEE Transactions on
Broadcasting, 68(4), 904-915, 2022,
doi: 10.1109/TBC.2022.3204229.
66
Targeting energy-hungry power amplifiers for sustainable RF
communications
Power amplifiers (PAs) play a major role in ensuring that communication
signals reach their destinations. But they are also voracious power
consumers, accounting for a staggering 80% of the total power
consumption in RF transmitters. This raises the obvious challenge of
how to boost PA power efficiency without sacrificing radio coverage
or quality. We investigated the potential of an AI-enabled solution to
address the nonlinear distortions RF PAs exhibit when working close
to their saturation level, where power efficiency is high, to achieve a
better tradeoff between energy efficiency and radio coverage.
© CEA
Jean-Baptiste Doré
Spectrum before and after DPD with proposed
conventional learning (CL).Using a 5G
waveform (OFDM) and power amplifier with
an 8 dB backoff (BO) (blue curves) introduces
leakage at the edge of the spectrum. To meet
a spectrum mask requirement, the BO must
increase and, consequently, the efficiency
of the power amplifier decreases. By using
the DPD and the proposed learning process,
leakage can be significantly reduced while
keeping the BO level low, making the use of
the power amplifier more energy efficient.
New dual-neural-network architecture makes digital
pre-distortion simpler and more resource-efficient
Currently considered the most promising PA linearization technique,
digital pre-distortion (DPD)—which entails adding a DPD module
before the PA to create a linear system—has been well documented in
the literature. There is one major hurdle, however, and that’s estimating
the inverse characteristics of the PA for the DPD module, especially
for dynamic PAs. We engineered a custom, two-neural-network
architecture to perform DPD in the polar (phase and amplitude)
domain. And, at just ten neurons for both neural networks, the
complexity is impressively low.
Meta-learning a game-changer for adaptive DPD
We deployed a meta-learning model on our architecture to make it
truly adaptive. Specifically, we chose MAML (model-agnostic meta
learning), an algorithm that can rapidly generalize from small gradient
updates to optimize NN parameters. In this research, we consistently
achieved performance levels close to the theoretical DPD optimum.
And, using online retraining on minimal samples and with few training
steps, we produced results on par with conventional learning methods.
Our numerical results were compelling, showing how our solution
adeptly adapts to different PA operating conditions.
04 I TELECOMUNICATION AND SECURITY FOR CONNECTED SOCIETY
Pulsed-laser deposition of lithium niobate
thin films for applications ranging from
5G to quantum
Florian Dupont
Lithium niobate (LiNbO3 or LN) is a staple in today’s smartphones, forming
the active layer in the RF filters used for waveband selection. The material is
also garnering attention as a candidate for optical phase modulators (OPM),
essential components for tomorrow’s quantum computers. CEA-Leti made an
advance in the deposition of LN that could open the door to broader use of
the material in high-performance devices.
The switch from bulk substrates to
monocrystalline thin films
Recent research has shown that monocrystalline LN
thin films support better RF filter performance than the
conventional bulk substrates. So, why aren’t LN thin films
more widely used? The current technique, crystal ion
slicing, which is used in Soitec’s Smart Cut™ process, can
only produce certain thicknesses. It is also expensive,
which means the RF filters produced using it are as well.
Finally, uniformity issues on larger (200 mm and 300 mm)
silicon wafers are a deal breaker for use in tomorrow’s
quantum applications. Research on growing the films goes
back decades, but major technical hurdles have prevented
growth from becoming a viable alternative until now, with
the addition of pulsed laser deposition (PLD) to the mix.
test the layers’ piezoelectric properties and make further
improvements to the deposition process. Another avenue
to pursue is 300 mm OPM prototyping using layers grown
using PLD.
© CEA
© CEA
CEA-Leti engineer
Left: Ellipsometry thickness uniformity mapping of
PLD-deposited LN thin film on 200 mm silicon wafer;
Center: XRD reciprocal space mapping showing
homoepitaxially-grown LN thin film crystalline quality;
Right: TEM Xsection image showing epitaxy of PLD-LN
on a seed layer grown on a 200 mm silicon substrate.
World-firsts achieved with PLD on large substrates
In PLD, laser ablation removes material from the target
to create a thin film on the substrate. This mostlystoichiometric phenomenon ensures that the layer obtained
has the correct LN phase. In this research, the crystalline
orientation of the layer on Al2O3 substrates with specific
orientations was meticulously controlled under specific
growth conditions. We made several notable advances:
•
Crystalline orientations like (113) and (223), which are
very close to common CIS orientations but difficult to
obtain through growth, were seen for the first time.
•
Films with uniform thickness (under 2%
non-uniformity) were successfully grown on 200 mm
silicon using a Solmates PLD reactor at 10 nm/min—
fast enough for industrial deployment.
•
We also grew epitaxial LN on 200 mm silicon
wafers—a world first. A specific seed layer was used
to allow for monocrystalline growth, which could
open the door to OPM applications for quantum.
Several patents were filed to protect this technology.
Up next: integration into devices for testing
CEA-Leti’s R&D partners are keeping a close eye on this
advance in semiconductor materials. The next steps will
be to integrate the process into a functional RF filter to
Impact
We made several advances in the deposition of LN
thin films on large substrates using PLD that could
lead to more efficient RF filters for 5G and beyond
telecommunications and OPMs for tomorrow’s quantum
computers.
Research partners
N/A
Further reading
• Sauze, L. C., et al. Homo-epitaxial growth of LiNbO3
thin films by Pulsed Laser deposition. Journal of Crystal
Growth, 601, 126950. ISSN 0022-0248, 2023,
doi: 10.1016/j.jcrysgro.2022.126950.
• Pershukov, I., et al. Heteroepitaxial growth of Lithium
Niobate Thin Films on sapphire substrates with different
orientations by Pulsed-Laser Deposition.
In 2022 IEEE International Symposium on Applications
of Ferroelectrics (ISAF) (pp. 1-4). Tours, France. 2022.
doi: 10.1109/ISAF51494.2022.9870044.
67
SCIENTIFIC
REPORT
2023
Evaluating the robustness of embedded
neural network models for more secure
Edge AI in a physical world
Pierre-Alain Moellic
© CEA
CEA-Leti engineer
Impact
The future certification of embedded, or
Edge, AI systems will require the reliable
evaluation of these systems’ robustness
against a set of state-of-the-art threats,
including physical attacks. AI integrity,
confidentiality, and availability, especially
in critical use cases, will depend on new
evaluation methods.
Research partners
Mines Saint-Etienne (IMT, MSE) under the ANR
(French national research agency) PICTURE
program and the European INSECTT project
(ECSEL). IRT Nanoelec (ANR-10-AIRT-05).
Further reading
• Dumont, M., et al. Evaluation of Parameter-based
Attacks against Embedded Neural Networks with
Laser Injection. In International Conference on
Computer Safety, Reliability, and Security. 2023.
• Hector, K., et al. Fault Injection and Safe-Error Attack
for Extraction of Embedded Neural Network Models.
In International Workshop on Security and Artificial
Intelligence (with ESORICS). Best paper. 2023.
• Hector, K., et al. A closer look at evaluating the BitFlip Attack against deep neural networks. In 2022 IEEE
28th International Symposium on On-Line Testing and
Robust System Design (IOLTS) (pp. 1-5). IEEE. 2022.
• Yao, F., et al. DeepHammer: Depleting the
intelligence of deep neural networks through targeted
chain of bit flips. In 29th USENIX Security Symposium
(USENIX Security 20) (pp. 1463-1480). 2020.
• Rakin, A. S., et al. Bit-flip attack: Crushing neural
network with progressive bit search. In Proceedings
of the IEEE/CVF International Conference on
Computer Vision (pp. 1211-1220). 2019.
68
The need for reliable methods to ensure
the safety and security of Edge artificial
intelligence systems has never been more
pressing. With regulations like the EU’s AI
Act sharpening the collective focus on AI
trustworthiness, risk, and acceptability,
CEA-Leti made a breakthrough on the oftenoverlooked physical threats to AI systems,
demonstrating a robust evaluation method
on a common IoT use case.
Tighter AI requirements call for new safety and security
assessment tools
The pioneering European AI Act is casting a long shadow
over AI-based systems and their use cases, drawing increasing
attention to safety and security. The legislation also lays the
groundwork for tomorrow’s AI certification programs. But you
can’t certify without first evaluating. Increasingly pervasive AI
systems handle sensitive data and perform sometimes-missioncritical tasks in a wide range of environments. The adversarial
landscape is just as broad, and comprehensively assessing it
is a difficult but crucial task. For machine learning models and,
especially, deep neural networks (DNNs), the attack surface is
particularly complex. These systems are, in effect, mathematical
abstractions (with their many theoretical flaws) physically
implemented in an environment that includes software and
hardware.
An IoT use case: deep neural networks at the Edge
CEA-Leti investigated the often-overlooked physical
vulnerabilities inherent to common internet of things (IoT) devices:
deep neural network models on 32-bit microcontrollers. Since
internal model parameters are stored locally in device memory,
they make excellent targets for attacks that seek to manipulate
these parameters to reverse-engineer the models or alter their
behavior. We demonstrated the impact of Bit-Flip Attacks (BFAs)
on AI models: just a handful of bit-flips could significantly degrade
the performance of convolutional neural network models, raising
serious security and evaluation concerns.
© CEA
04 I TELECOMUNICATION AND SECURITY FOR CONNECTED SOCIETY
A laser injection
platform used
for evaluating
the robustness
of embedded
neural networks.
© CE A
Until now, most research has focused on DRAM. We
have demonstrated the relevance and effectiveness
of using bit-sets (instead of bit-flips) for a BFA-like
attack, to extract confidential information from a
protected black-box model. By analyzing the model’s
output decisions with and without faults to discover
parameter values, attackers can then use them in
reverse-engineering attacks. Our research charts
a course toward robust evaluation protocols for
embedded AI models on Cortex-M platforms with
Flash memory. We used theoretical analysis and laser
fault injection to better understand the relationships
between model characteristics and attack efficiency.
Our work has also demonstrated the value of
simulation in facilitating the evaluation of AI models.
These—and future—strides in the evaluation of AI
security will be crucial to certify and design protection
mechanisms for embedded AI systems.
© CEA
Laying the groundwork for robust AI
certifications
Kevin Hector
CEA-Leti PhD student
Kevin Hector won a
Best Paper Award for
this research at the
International Workshop
on Security and Artificial
Intelligence (SECAI)
2023 in conjunction with
ESORICS 2023.
69
SCIENTIFIC
REPORT
2023
MARKET
NEWS
© ABCDstock / AdobeStock
FROM OUR R&D PARTNERS
PEL® 4.0​​​​​
AN INNOVATIVE, CONNECTED CYLINDRICAL
BUSHING FOR PREDICTIVE MAINTENANCE
IN CONSTRUCTION VEHICLES​​
PEL® 4.0​​​​​ is an innovative sliding bushing solution that includes multilevel wear
sensors, RFID tag and antenna. The RFID tag enables users to track wear and
facilitates predictive maintenance. This innovation is designed to withstand the
harsh conditions of construction sites.
https://urlz.fr/nXkn
70
© ImageFlow / IRStone - Adobe Stock
04 I TELECOMUNICATION AND SECURITY FOR CONNECTED SOCIETY
CEA & SCHNEIDER ELECTRIC EXTEND
R&D COLLABORATION
Grenoble, France – 11 October, 2022.
CEA & Schneider Electric Extend R&D Collaboration To Bring Secure and Resilient Digital
Solutions To Energy Management and Industrial Automation.
CEA and Schneider Electric, the global leader in the digital transformation of energy management
and automation, have agreed to extend their joint laboratory collaboration for three more years.
The shared objective is to continue to test and fortify the security of world-leading process-andenergy technologies for greater resilience across industries. © P. Jayet
Michael Pyle, Director
of Product Cybersecurity
at Schneider Electric
and Sébastien Dauvé,
CEA-Leti CEO.
Michael Pyle, Director of Product Cybersecurity
at Schneider Electric, said:
“Our collaboration with CEA has allowed us to leverage our
in-depth knowledge of commercial and industrial applications
and CEA’s deep technical skill set to build a strong, two-way
partnership that will benefit both Schneider Electric and our
customers and this will be pursued for the next three years.“
https://urlz.fr/nXjr
71
© xiaoliangge - Adobe Stock
SCIENTIFIC
REPORT
2023
72
05 I GENERIC MATERIALS AND CHARACTERIZATION
GENERIC
MATERIALS AND
CHARACTERIZATION
CEA-Leti is one of the few research
institutes in the world to conduct
advanced research in materials,
processes, and characterization.
This allows us to bring a “materialto-system” approach to prototype
development and fabrication.
In 2023 we made exciting advances
ranging from new materials to their
characterization and integration.
3D integration and packaging played
pivotal roles in our developments.
Our exploration of bio-based resists
could contribute to huge reductions
in solvent use. Finally, an advanced
self-assembly technique could
be a game changer in terms of
manufacturing throughputs.
Scientific Advisor
to the Silicon
Components Division
© UtopikPhoto / CEA
Jean-Paul Barnes
© UtopikPhoto / CEA
Gaël Pillonnet
Scientific Advisor to
the Technology
Platform Division
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SCIENTIFIC
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2023
ADVANCED PACKAGING
CEA-Leti’s advanced heterogeneous packaging research leverages expertise in chiplets,
3D and hybrid integration, and flexible electronics. We have the full range of technologies
needed to break up monolithic circuits into modules, or chiplets, and package them into
vertically-stacked circuits using 3D integration techniques. We can also integrate ultrathin silicon components into labels and transfer them onto flexible printed devices. From
automotive to health, a wide range of industries will be counting on advanced packaging
to deliver simpler, faster, and cheaper chip designs that integrate more functions and
offer greater performance and versatility.
Advanced packaging
collaborations and partnerships
•
•
•
•
On-chip LiDAR startup
SteerLight
EU H2020 advanced LiDAR
project Tinker
The CEA Starac project
(with CEA-List)
Intel
More complex chip packaging architectures, whether stacked or
ultra-thin, will require new technologies to ensure tighter integration
and new fabrication processes compatible with the cost and
throughput requirements of volume manufacturing. We made
several notable advances in optical networks-on-chip for highperformance computing, self-assembly for die-to-wafer bonding,
and on-chip LiDAR (for CEA-Leti startup SteerLight). We also
developed a new solution in the field of flexible hybrid electronics,
which could, by combining silicon and printed flexible electronics,
bring new levels of performance to use cases like functionalized car
dashboards and wearable patches for health applications.
From monolithic many-core architectures to chiplets:
a new paradigm and new challenges
CEA-Leti has developed significant expertise in chiplets. In general,
high-performance computing—used in artificial intelligence, climate
modelling, and military applications, for example—has depended
on monolithic many-core processors at advanced technology nodes
for devices that measure several square centimeters. Today, there
is a move to partition smaller processors called chiplets on silicon
interposers; this is a mature technology. These tiny circuits can be
produced at a lower cost and offer higher manufacturing yields.
They are also lower-power and more versatile. CEA-Leti is coming
up with novel integration architectures to respond to the new
integration challenges created by chiplets.
74
Hydrophilic and hydrophobic surfaces
integrated together for water droplet
containment for self-assembly process.
Another area where CEA-Leti made advances in 2023 was
die-to-wafer bonding and, specifically, self-assembly.
Traditional DTW faces challenges in combining accuracy
with high throughput, especially for small dies. Several
advances brought a novel self-assembly technique using
water droplets closer to industrial deployment. The process
requires precision in surface preparation, balancing
hydrophilicity, surface energies, and nano-topography.
It aims for integration on hybrid surfaces like Cu and
SiO2, ensuring Cu integrity and optimal bonding quality.
According to CEA-Leti’s Emilie Bourjot, “Improved
bonding, controlled step height,
and compatibility with copper pad
fabrication are among the benefits
of this approach, which promises
smoother integration into future
technology process flows. This kind
of process could make the massproduction of devices with more
Emilie
complex 3D architectures possible.”
Bourjot
In related research, CEA-Leti and Intel
also worked together on self-assembly to achieve highthroughput die-to-wafer bonding (see page 78).
© CEA
CEA-Leti is helping develop what is considered a
disruptive approach to high performance computing
(HPC): optical network-on-chip (ONoC) technology.
Photons (light) have the potential to deliver fast on-chip
communication, increasing the bandwidth and reducing
the power consumption of high-performance computers.
We continued to tackle the main technological challenges
inherent to our architectural vision of an optical network-onchip approach to chiplets: a scalable, low-profile interface
between the chiplets and network, decentralized routing
to reduce data movement within the system, thermal
management compatible with optical communications,
and individual chiplet performance in multiple-chiplet
integrations. “We were able to successfully co-integrate
3D interconnections and photonic devices using a
newly-demonstrated approach to 10 µm diameter by
100 µm high through-silicon via formation and copper
metallization inside a photonic chip, 40 µm diameter
etched backside cavities under
optical micro-ring resonators for
improved thermal isolation, and
effective thermomechanical stress
management of the 100 µm thinned
photonic interposer for assembly
processes. We have now moved on
to assembly and packaging, and a full
demonstrator
is expected in 2024,”
Jean
Charbonnier
said CEA-Leti’s Jean Charbonnier.
More complex 3D chip architectures will require
new fabrication processes
© CEA
Taking NoCs further: optical networks-on-chip for
high-performance computing
75
© Quardia Inc. - Adobe Stock
© P. Jayet / CEA
05 I GENERIC MATERIALS AND CHARACTERIZATION
SCIENTIFIC
REPORT
2023
ChipInFlex, a new process for a higher level
of silicon integration on flexible substrates
This wafer-level process developed at CEA-Leti enables
the integration of bare dies of different types. The electrical
interconnections are made via the deposition of stud bumps on
bare dies followed by thermocompression. This is the first time
bare silicon dies have been integrated into a flexible film and
collectively thinned onto a wafer carrier. Two demonstrators
were fabricated, one with an ultra-thin silicon strain gauge, and
the other with an ultra-thin RFID tag, and tested successfully.
© CEA
Objects that let users interact with them naturally and
intuitively are the way of the future. The automotive and
smartphone industries, at the forefront of this trend, are
driving demand for electronics that can be integrated into
curved surfaces like car dashboards and steering wheels
or smartphone cases, for example. The interfaces for these
kinds of products typically depend on electronics printed
on flexible substrates rather than fabricated on silicon
wafers. “As impressive as they are, today’s printed
electronics still cannot rival silicon’s
computational and data storage
performance. In terms of integration,
advanced silicon technology nodes
have electrical interconnections that
are too small in size and pitch to be
connected directly to flexible printed
components,” said CEA-Leti’s
Jean-Charles
Souriau. CEA-Leti is
Jean-Charles
Souriau
introducing an intermediary step—
encapsulating the chips in a flexible label and fanning out
the pads to make them compatible with printed circuit
design rules—that is getting excellent results.
76
3D integration overcomes the last technological
hurdle to self-driving cars
LiDAR (light detection and ranging) is considered the “final
frontier” in truly autonomous driving. The technology
exists, but the sensors need to be improved dramatically
and made much more compact to be integrated into
autonomous driving systems. CEA-Leti leveraged flipchipping and through-silicon vias to come up with a new
integration that gets closer to those objectives. A CEA-Leti
startup, SteerLight, will be able to integrate these advances
into its automotive LiDAR chips.
“Current MEMS LiDARs don’t meet
the specifications of autonomous
driving systems. We believe that
silicon solid-state LiDARs are the
answer. We have developed an
optical phase array beam steering
device that marks a major step in this
direction. But the packaging of the
Thierry
device still needs to be optimized
Mourier
and miniaturized, and that’s what
we focused on in 2023, including through the European
Tinker project,” said CEA-Leti’s Thierry Mourier.
© UtopikPhoto / CEA
Silicon and flexible printed electronics:
better together
05 I GENERIC MATERIALS AND CHARACTERIZATION
Further reading
• Bourjot, E., et al. Challenges with self-assembly applied to dieto-wafer hybrid bonding. Chip Scale Review, 27(5), 25-31. 2023.
• Bourjot, E., et al. Integration and process challenges of self
assembly applied to die-to-wafer hybrid bonding. In 2023
IEEE 73rd Electronic Components and Technology Conference
(ECTC) (pp. 1397-1402). Orlando, FL, USA. 2023.
doi: 10.1109/ECTC51909.2023.00239.
• Malhouitre, S., et al. Bringing photonic technology to
3D-stacked computing systems: Creating the low-latency
“POPSTAR” optical network-on-chip through heterogeneous
integration on a photonic interposer. Photonic Integrated
Circuits, IV, 18-22. 2023.
• Mourier, T., et al. Advanced 3D integration TSV and flip chip
technologies evaluation for the packaging of a mobile LiDAR
256 channels beam steering device designed for autonomous
driving application. In 2023 IEEE 73rd Electronic Components
and Technology Conference (ECTC) (pp. 239-246). Orlando, FL,
USA. 2023. doi: 10.1109/ECTC51909.2023.00049.
• Saint Patrice, D., et al. Process Integration of Photonic
Interposer for Chiplet-Based 3D Systems. In 2023 IEEE 73rd
Electronic Components and Technology Conference (ECTC).
2023.
• Souriau, J. -C., et al. Flexible Hybrid Electronics Including
Ultrathin Strain Sensors or Radio Frequency Identification Dies
Manufactured on Wafer Silicon Carrier. IEEE Transactions on
Components, Packaging and Manufacturing Technology,
13(7), 913-919. 2023. doi: 10.1109/TCPMT.2023.3293528.
• Suarez Berru, J. J., et al. Demonstration of a Wafer Level
Face-To-Back (F2B) Fine Pitch Cu-Cu Hybrid Bonding with High
Density TSV for 3D Integration Applications. In 2023 IEEE 73rd
Electronic Components and Technology Conference (ECTC)
(pp. 97-102). Orlando, FL, USA. 2023.
doi: 10.1109/ECTC51909.2023.00025.
© CEA
The purpose of the Tinker project was to integrate the
photonic device onto a silicon interposer housing the
CMOS control circuit and other subsystems. A prototype
was fabricated using flip-chipping and through-silicon
vias for tighter integration and distribution of the
electrical contacts on the photonic die’s back side. The
main challenges to fabricating the device were adapting
mid-process-flow TSVs to the SOI substrate and managing
the thinning of the substrate to 130 µm. Despite these
issues, the photonic die was successfully attached to
the silicon interposer. A functional demonstrator will be
exhibited at LOPEC, the international large-area, organic,
and printed electronics convention, in March 2024.
The demonstrator is the first-ever functional
integration of a photonic device on a silicon
interposer using state-of-the-art mid-process TSV
technology coupled with fine-pitch flip-chip bonding.
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SCIENTIFIC
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2023
CEA-Leti and Intel join forces on novel
self-assembly technology that could enable
high-throughput die-to-wafer bonding
Frank Fournel
© UtopikPhoto / CEA
CEA Fellow & Head
of Bonding Process
Engineering
The direct-placement die-to-wafer bonding used in
today’s semiconductor fabs relies on pick-and-place
processes that cannot currently achieve both submicron placement accuracy and the high throughput
required for cost-competitive volume manufacturing.
Breakthrough processes are needed, and CEA-Leti
and Intel are tackling the challenge with a new selfalignment process that could be a game changer.
Direct bonding: the current state of the art and new challenges
Wafer-to-wafer direct bonding is well understood, and the literature is full
of studies of the different bonding mechanisms of silicon, silicon dioxide,
copper, and even hybrid surfaces. In fact, hybrid bonding has been in
production at Sony for years, mainly for imaging devices. Today, however,
this kind of wafer-to-wafer direct bonding must overcome some new
hurdles as new substrates and applications emerge. Die-to-wafer bonding,
used prior to hybrid bonding for optoelectronic applications integrating
heterogeneous (III-V and silicon) materials, offers an interesting alternative,
but is bumping up against limitations in accuracy and throughput. The
pick-and-place tools employed in this type of process can only handle
1,000 dies per hour at sub-micron placement accuracy—not nearly
enough for the demands of volume manufacturing.
A precision self-assembly process that could exponentially
increase throughput
Impact
It is still premature to discuss specific
impacts. However, die-to-wafer hybrid
bonding is the next significant challenge
in 3D integration, and self-alignment
could be a game-changing enabler.
Self-alignment has emerged as a potential solution, but previous
attempts have been very manual and, therefore, not compatible with
the demands of industrial fabrication. And there are other challenges
around modern wafers, including surface preparation of materials
like pure copper, the logistics of cavity-based wafer handlers, and
cleanliness issues created by faster pick-and-place tools. CEA-Leti has
been investigating a new approach that could enable an industriallydeployable self-alignment process for hybrid surfaces.
Using water’s capillary forces to "pick up" dies
Research partners
Intel
78
Our understanding of the link between water and the direct bonding
of silicon dioxide has advanced by leaps and bounds in recent years.
CEA-Leti and Intel have been focusing on fine self-alignment using a
droplet of water, harnessing the capillarity of water to pick up the die,
© P. Jayet / CEA
05 I GENERIC MATERIALS AND CHARACTERIZATION
Self-aligned die to wafer bonding using hydrophilic
and hydrophobic contrast.
which then self-aligns as the water evaporates. What
opens the door to industrial deployment is the fact that
die surfaces can now be prepared for self-alignment
using standard microelectronics processes. However,
there are still two approaches in the running: complete
collective bonding or high-speed die sorting with rough
alignment. CEA-Leti is exploring how each technique,
with its advantages and drawbacks, could potentially
be beneficial in different use cases. Precision placement
to within 200 nm was achieved using this still-immature
process, outperforming conventional pick-and-place. The
industrial roadmap will still have to address reducing step
height to 1 µm and the development of new equipment,
but these early results are promising.
Further reading
• Bourjot, E., et al. Challenges with self-assembly
applied to die-to-wafer hybrid bonding. Chip Scale
Review, 27(5), 25-31. 2023.
• Bourjot, E., et al. Integration and Process Challenges
of Self Assembly Applied to Die-To-Wafer Hybrid
Bonding. In 2023 IEEE 73rd Electronic Components
and Technology Conference (ECTC) (pp. 1397-1402).
Orlando, FL, USA. 2023.
doi: 10.1109/ECTC51909.2023.00239.
• Fournel, F., et al. Optoelectronic and 3D
Applications with Die to Wafer Direct Bonding: From
Mechanisms to Applications. ECS Meeting Abstracts,
MA2022-02, Advanced 3D Interconnect Technologies
and Packaging, D03, 853. 2022.
doi.org/10.1149/MA2022-0217853mtgabs
• Fournel, F., et al. Direct bonding: a key enabler for
3D technologies. Chip Scale Review, 26(5), 6-12. 2022.
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2023
Lab-scale hard X-ray photoelectron
spectroscopy (lab-HAXPES)
for MOSc-HEMT characterization
Eugénie Martinez
© UtopikPhoto / CEA
CEA-Leti engineer
Advances in microelectronics are creating demand
for more powerful characterization techniques and
finer control over critical interfaces that impact
device operation and performance.
Lab-scale HAXPES sheds new light on device
electrical properties, providing valuable information
for the optimization of fabrication processes.
Both non-destructive and invasive characterization methods
are needed
Impact
Lab-HAXPES is a powerful new
characterization tool that can measure
realistic structures without artificially
reducing layer thicknesses to access
the critical buried interfaces, directly
impacting the reliability of the analysis
of multilayer structures used in device
fabrication.
Research partners
LTM (a CNRS lab), Institut Pascal (a CNRS
lab), Université Libre de Bruxelles.
80
X-ray photoelectron spectroscopy (XPS), compatible with
semiconductor fabrication environments, has evolved in recent years
with the introduction of hard X-ray sources into innovative lab-scale
spectrometers. The new technique, hard X-ray photoelectron
spectroscopy (HAXPES), is emerging as a powerful tool for the
characterization of materials below the surface. CEA-Leti is applying
HAXPES to the chemical characterization and quantification of
materials for process development and optimization.
New insights into buried interfaces for improved device
performance
Lab-scale HAXPES (“lab-HAXPES”) is a welcome addition to the
existing repertoire of surface-sensitive characterization techniques
available to microelectronic device developers. It offers more
dependable analysis of the critical buried interfaces that play such
an important role in fabrication processes and in the electrical
performance of the final device. CEA-Leti completed an initial
evaluation of lab-HAXPES on a series of material characterization
case studies to assess the technique’s ability to detect deep buried
interfaces and determine its limitations in terms of sensitivity. The
technique was then applied to a GaN-based power transistor
development project.
05 I GENERIC MATERIALS AND CHARACTERIZATION
© CEA
Lab-based HAXPES for the analysis
of critical buried interfaces.
A powerful, accurate tool for power transistor
and memory R&D
In this research, lab-HAXPES provided insights into
gallium oxidation at the vital Al2O3/GaN interface of
MOSc-HEMT devices, revealing that GaN oxidation
escalates with increased Al2O3 thickness. The technique
was also used to assess the impact of etching and postdeposition annealing on this interface composition,
highlighting the significant effects that these processes
have on device performance. Finally, we combined
lab-HAXPES with inelastic background analysis (IBA)
to determine buried layer thicknesses and interface
locations within complex structures such as Al2O3 and
HfO2 layers used in memory devices.
Further reading
• Bure, T. R., et al. Assessing advanced methods in
XPS and HAXPES for determining the thicknesses
of high-k oxide materials: From ultra-thin layers to
deeply buried interfaces. Applied Surface Science,
609, 155317. ISSN 0169-4332. 2023.
doi.org/10.1016/j.apsusc.2022.155317.
• Spelta, T., et al. Impact of etching process on
Al2O3/GaN interface for MOSc-HEMT devices
combining ToF-SIMS, HAXPES and AFM. SolidState Electronics, 208, 108743. ISSN 0038-1101.
2023. doi.org/10.1016/j.sse.2023.108743.
• Renault, O. et al. New directions in the analysis
of buried interfaces for device technology by hard
X-ray photoemission. Faraday Discussions, 236,
288-310. 2022.
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2023
TMD-like semiconducting materials grown
at BEOL-compatible temperatures
Stéphane Cadot
© CEA
CEA-Leti engineer
Traditional silicon-based devices are bumping up against their physical
limits in terms of miniaturization. 2D semiconducting transition metal
dichalcogenides (TMDs) offer a unique atomically-thin layered structure
and immunity to short-channel effects, making TMDs like MoS2 and
WS2 attractive alternatives. However, these materials are grown at very
high temperatures (typically in excess of 850 °C) not compatible with most
materials. Plus, the toxic, corrosive chalcogen source used for deposition
imposes heavy safety constraints. Finally, TMDs have a lamellar structure
that is inherently non-adherent, making their integration extremely
challenging. CEA-Leti is investigating more practical, safer alternatives.
Graphical abstract representing
the SnS-to-SnS2 phase transition
observed by STEM
(cross-sectional view).
© CEA
2D semiconducting materials
like TMDs (transition metal
dichalcogenides) have garnered
interest as enablers of sub-5 nm and
More-than-Moore technologies. But
their high synthesis temperatures
are not compatible with back-endof-line processes. CEA-Leti grew
two TMD-like semiconductors
at much lower BEOL-compatible
temperatures, paving the way
for the fabrication of thin-film
transistors and switching, memory,
and energy storage devices.
Innovations in materials needed to shrink component size and
power consumption
Impact
2D TMD integration conventionally
involves high-temperature growth
on a dedicated substrate, followed
by polymer-assisted transfer of the
TMD layer. This research confirms
that the direct integration of TMD-like
2D materials into any kind of device
architecture is possible, opening up
exciting opportunities for More-thanMoore technologies.
Research partners
LMGP
Further reading
• Chatmaneerungcharoen, B., et al. Synthesis of
In-Plane Oriented Tin Sulfides by OrganosulfurMediated Sulfurization of Ultrathin SnO2 Films.
Chemistry of Materials, 34(13), 5842–5851. 2022.
• Cadot, S., et al. A novel 2-step ALD route to
ultra-thin MoS2 films on SiO2 through a surface
organometallic intermediate. Nanoscale, 9, 538546. 2017.
82
In-plane oriented tin sulfides obtained by organosulfurmediated sulfurization of ultrathin SnO2 films
Tin disulfide (SnS2) is a post-transition metal dichalcogenide with
properties similar to MoS2 but with lower crystallization temperatures
and better adhesion properties. Starting with ultrathin tin dioxide (SnO2)
layers deposited by ALD on SiO2 /Si substrates, different non-toxic
and volatile organosulfur compounds were tested for their ability to
convert tin oxide into tin sulfide. Tert-butyl disulfide (TBDS) directly
converted SnO2 into SnS2 at a mere 350 °C. Tert-butylthiol (TBT) formed
orthorhombic SnS at 300 °C. The SnS2 and SnS layers obtained display a
lamellar and 001-oriented structure with relatively large grains.
A deeper understanding of phase-change mechanisms will
support future 2D semiconductor development
Interestingly, sulfurization using TBT takes far less time than with
TBDS, and it was found that TBDS vapor was able to convert SnS into
SnS2 even faster. This was ascribed to better diffusion of sulfur species
through SnS compared to SnS2, the latter acting as a diffusion barrier.
For SnS-to-SnS2 conversion, sulfur species penetrate through grain
boundaries, laterally diffuse between the SnS 001 planes, and induce the
phase change through a zip mechanism which was observed using highresolution STEM microscopy. Based on these findings, lamellar (or even
2D) disulfides can be implemented at BEOL-compatible temperatures
using a safe and robust process compatible with most CVD tools.
05 I GENERIC MATERIALS AND CHARACTERIZATION
Making cleanrooms cleaner with eco-friendly
chitosan water-based lithography resists
for sustainable nanofabrication
Isabelle Servin
CEA-Leti eco-design engineer
& sustainability advisor
With semiconductor-industry stakeholders
around the globe now joining forces
to address climate challenges through
initiatives like the Semiconductor Climate
Consortium, the path to net zero by 2050
has been clearly charted. CEA-Leti is tackling
critical nanofabrication processes like
photolithography to eliminate hazardous
solvents and alkali-based solutions by using
water-soluble bio-sourced chitosan resists
derived from seafood industry waste.
Making fabrication processes safer and cleaner for
people and the planet
Photolithography is the main process in nanofabrication.
Unfortunately, today’s synthetic petroleum-derived
photoresists require the use of significant amounts of
organic solvents and alkali-based solutions—both of which
present environmental and human health risks. A watersoluble photoresist solution would go a long way toward
making photolithography more sustainable. Chitosan,
which is a natural polysaccharide obtained mainly from
seafood-industry waste, would be compatible with water
as a “green solvent” during patterning. CEA-Leti recently
completed the first-ever transfer of this solution from lab
to pilot fabrication line and did a lifecycle assessment
(LCA) of the new, bio-based process.
New, bio-based photoresists tested at the 300 mm
pilot scale
The chitosan films, just 100 nm thick, were spun onto wafers
with a high degree of precision, and a uniform, defect-free
coating was obtained on 200 mm and 300 mm wafers. The
water-soluble films were successfully deployed for DUV
photopatterning down to 1 μm followed by transfer etching
onto the silicon substrate of 35 nm deep features with good
pattern fidelity. The process is cleanroom-compliant and
the solution is ready-to scale up for volume production via a
dedicated aqueous-based unit. While the initial results were
promising, additional improvements to printing sensitivity
Comprehensive lifecycle assessment (LCA)
confirms environmental benefits
The chitosan resists dramatically outperformed
conventional fossil-based processes. The LCA revealed
a 50% reduction in environmental impacts, which factor
in CO2 emissions, electricity consumption, and chemical
usage. When applied to a high-volume manufacturing
scenario, the annual savings could be substantial. CEA-Leti’s
development of more sustainable cleanroom processes will
continue through partnerships with semiconductor industry
stakeholders and through European projects like RESIN
GREEN, which will begin in 2024.
© CEA
© UtopikPhoto / CEA
and resolution will need to be achieved, most likely by finetuning the material properties and testing novel formulations.
Patterning with water-soluble
bio-based chitosan resist.
Impact
CEA Leti is pioneering water as the ultimate “green
solvent” in support of the European Green Deal and
semiconductor industry sustainability goals. Replacing
petroleum-based resists with water-soluble, bio-sourced
chitosan could make a huge dent in the environmental
impacts of nanofabrication processes. Partnerships with
industry stakeholders promise to accelerate the adoption
of these sustainable technologies.
Research partners
CNRS, Université Claude Bernard Lyon, INSA Lyon,
Ecole Centrale de Lyon, Université de Haute-Alsace.
Further reading
• Sysova, O et al., «Chitosan as a Water-Developable
193 nm Photoresist for Green Photolithography»,
ACS Applied Polymer Materials, 4 (6), 4508-4519. 2022.
doi.org/10.1021/acsapm.2c00475.
• Servin, I. et al., «Water-soluble Bio-sourced Resists for
DUV Lithography in a 200/300 mm Pilot Line Environment»,
Micro and Nano Engineering, 2023.
doi.org/10.1016/j.mne.2023.100202.
• Servin, I. et al., «Chitosan as a Water-based Photoresist for
DUV Lithography», Proc. Of SPIE 2023 Proceedings Volume
12498, Advances in Patterning Materials and Processes XL;
1249818, 2023. doi.org/10.1117/12.2658423.
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© ipopba - Adobe Stock
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06 I EMERGING DEVICES TO IMPROVE HUMAN HEALTH
EMERGING DEVICES
TO IMPROVE
HUMAN HEALTH
© UtopikPhoto / CEA
Pascal Mailley
Scientific Advisor to the Technology
for Biology and Health Division
CEA-Leti’s health R&D addresses
prevention, diagnostics, and
treatment and encompasses
human, animal, and environmental
health. In 2023 we made advances
in sensors to detect pathogens
and microplastics in food and the
environment, in monitoring for blood
pressure and sleep apnea, and in
new weapons to fight bacteria. We
investigated emerging technologies
for embryo viability testing and
cancerous tissue analysis. It was
also a big year for our organ-onchip research. And, we developed
bioresorbable biomaterials that
could enable innovative monitoring
implants. Finally, our WIMAGINE®
brain implant helped a spinal cord
injury patient move again, opening
the door to future use in stroke
rehabilitation.
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ADVANCED SENSING AND
STIMULATION TECHNOLOGIES
DRIVE INNOVATIONS IN PATIENT
MONITORING, TREATMENT,
AND MOBILITY
Health—human, animal, and environmental—is at the top of the list of society’s
grand challenges. Tomorrow, the role of technology will expand beyond electronic
medical records and remote consultations. The advanced devices being developed
at CEA-Leti will contribute to powerful solutions throughout the health journey,
from wellness and prevention to diagnostics and treatment.
© Chr. Morel / CEA
Imagine if patients with mood disorders could
count on their smartphones to keep relapses—and
hospitalizations—at bay by providing a very early
warning based on the sleep, heart rate, and other data
that is already being collected by most smartphone and
smartwatch users?
“Our hope is that one day the
unique R&D pipeline we are creating
at CEA-Leti will become the new
standard for the efficient delivery of
novel medical solutions to patients,”
said CEA-Leti’s Abdelmadjid Hihi.
The year 2023 was a productive one,
resulting in several major advances in
patient monitoring and mobility and
medical devices.
And what if caregivers were able to send patients home
with a non-invasive device for the continuous monitoring of
CO2—a common indicator of a variety of conditions—but
without the need to have the patient exhale into a bulky
monitor or wait for blood samples to come back from a lab?
Abdelmadjid
Hihi
Our technologies can also help patients with spinal cord
injuries control their gait naturally using a brain-spine
interface system. Recent clinical trials are pushing back the
limits of what this kind of neuroprosthesis can do, giving
new hope to patients suffering from a loss of mobility.
The rise of artificial intelligence and dramatic improvements
in sensor technologies are revolutionizing human health
and well-being. Sensors are getting smaller, more powerful,
and more energy efficient, making it easier than ever to
monitor just about anything—or everything.
Finally, we are working with medical device manufacturers,
academic research labs, and clinicians to forge novel
solutions built on ingenious integrations of our state-ofthe-art circuits, sensors, and actuators.
86
New breakthroughs in monitoring people’s behaviors and
mental states will be deployed in novel solutions.
“The idea is not to control
individuals, but to assist them
in adapting their responses to
rapidly-changing circumstances,”
said CEA-Leti Research Director
Christelle Godin. “This includes
identifying potential harmful
situations while ensuring that users’
data
is kept away from prying eyes.”
Christelle Godin
© CEA
And for the developers of tomorrow’s medical devices, we
are designing a clinical trial protocol for the exploration of
blood pressure dynamics that will ensure robust, accurate
measurements and stable performance over time—the
ideal characteristics for simple, reliable at-home monitoring
systems.
Ubiquitous AI and sensing will power trustworthy
human monitoring solutions
© CE A
© Kiattisak - Adobe Stock
06 I EMERGING DEVICES TO IMPROVE HUMAN HEALTH
Salam
Hamieh
love to see my algorithm
implemented on a connected
watch,” she said. “The award
really gave me a boost, and
I appreciate my supervisors’
initiative in signing me up and
their support helping me finish
on time to be considered.”
Beyond health monitoring, this technology can help reduce
motor vehicle accidents caused by driver distraction or
drowsiness and improve the safety of workers in hazardous
environments by monitoring their mental states and actions.
© uOttawa
In research with Dr. Hussein Al Osman’s team at the University
of Ottawa on relapse detection in mental health patients,
anomaly detection techniques were employed to pick up
on relapses in patients with mental disorders. Heart rate,
sleep, and daily activity patterns are recorded during healthy
periods and used to train models on typical behavior patterns.
When anomalies or deviations from the learned patterns are
detected, the likelihood of a relapse can be determined. As a
specialist in applied AI, affective computing, human-computer
interaction, and multimedia systems, Al Osman immediately
saw the potential synergies with CEA-Leti when he first met
with scientists from the institute in 2019.
This research also won
CEA-Leti PhD student Salam
Hamieh, who developed
the algorithm, an honorable
mention in the ICASSP Grand
Challenge e-prevention
category in 2023. “I would
Dr Hussein Al Osman
© CEA
“My experience with CEA-Leti has highlighted
the value of international collaborations. Given
the success of this partnership, I am now more
motivated to cultivate other collaborations beyond
the frontiers of North America,” he said. “I have no
doubt that the deep professional relationships and
personal friendships I’ve forged with the team at
CEA-Leti will endure.”
Steering wheel equipped
with grip sensors.
Detection of hands activity
by mean of a camera and
IA algorithm.
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Test device for carbon dioxide measurement
through the skin. A liquid solution (representing
blood) and membrane (representing the skin)
are used to measure flow rate and pressure.
Wearables could enable continuous blood pressure
and CO2 monitoring for improved at-home
prevention and care
An at-home capnometry (CO2 monitoring) wristband
would provide substantial benefits to patients suffering
from respiratory injuries or obstructions caused by chronic
obstructive pulmonary disease (COPD) and infectious
diseases like Covid-19, for example. Capnometry can
also detect alveolar hypoventilation and hypercapnia.
In clinical settings, the solution could help with postoperative monitoring or for the monitoring of patients
coming off ventilators. CEA-Leti recently developed a
new architecture for non-dispersive infrared (NDIR) optical
measurement close to the skin’s surface, combined with
an open chamber design facilitating continuous air flow in
the collection cell. CEA-Leti’s Anne Koenig explained,
“We developed a model of the temporal dynamics
of CO2 exchange between blood and the device’s
gas channel using convection-diffusion equations. A
Kalman filter could be used to recursively estimate
blood CO2 concentrations over time, allowing real-time
tracking of blood CO2 pressure.”
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© A. Aubert / CEA
© CEA
The blood pressure meter trial generated data that will
deepen our understanding of blood pressure variations
and optical sensor characteristics at
individual-patient and population
levels—the foundation for safe,
repeated measurement protocols.
“Hypertension is a major and often
underdiagnosed cause of premature
death affecting increasingly younger
populations.
The development of
Emma
a
reliable,
accurate
blood pressure
Villeneuve
monitor is vital to prevent avoidable deaths and chronic
disease,” said Emma Villeneuve of CEA-Leti.
© A. Aubert / CEA
Blood pressure and CO2 are both crucial health indicators.
And yet, both are difficult to measure regularly and reliably
at home. Continuous home monitoring could help identify
high-risk patients, improve early diagnosis of a variety of
conditions, better target treatment, and improve postoperative outcomes. CEA-Leti and its partners made headway
in 2023 with a pioneering clinical trial of a cuffless, opticalsensor-based blood pressure meter and with a bracelet that
can non-invasively monitor CO2 through the skin.
Physiological measuring platform
(top) and commercial pulse wave
velocity monitor (bottom).
While this research focuses on CO2 transport from blood to
the collection cell, the proposed model can be extended
to other volatile molecular species (e.g., ethanol, acetone,
isoprene, methane) and diluted blood gases like oxygen
or hydrogen, offering vast potential for monitoring a wide
range of physiological parameters.
Translating thought into movement: Brain-Spine
Interface (BSI) technology
CEA-Leti and partners continue to break new ground with
the Brain-Spine Interface project at the Clinatec biomedical
research center. Electrocorticogram (EcoG) signals are
captured by the WIMAGINE® intracranial implant and
translated into commands sent to a spinal-cord stimulator,
effectively mobilizing muscle function. This technology
could one day enable patients with spinal cord injuries to
recover their mobility.
Henri Lorach
CEA-Leti and EPFL in Switzerland have been working
together on the technology since 2019. “Back in
2016, our research—on animals, not yet humans
at that point—showed that it was possible to link
intent at the motor cortex to the stimulation of the
spinal cord, opening up a viable path to restoring
movement to patients suffering from paralysis. That
advance set us on a quest for a technology capable
of materializing this link. The WIMAGINE® wireless
intracranial implant developed by CEA-Leti and
Clinatec performs this function with a high degree
of fidelity and stability over time,” said EPFL’s Henri
Lorach, a member of the team at the NeuroRestore
research, innovation, and treatment center.
© Chr. Morel / CEA
An ongoing clinical trial called STIMO-BSI (Stimulation
Movement Overground – Brain Spine Interface)
demonstrated that a paraplegic patient was able to regain
natural gait control based on his brain control . Additionally,
it has provided new confirmation that consistent activation
of a spinal cord simulator via the WIMAGINE® implant can
cause a lasting return of neurological function, even after
stimulation ceases. “This is an exciting
new development that marks a step
toward practical applications. We
have now expanded our training
environments outside the lab so that
patients can use the BSI at home,”
said CEA-Leti’s Guillaume Charvet.
The recent clinical trials have pushed
Guillaume
back the limits of neuroprosthetics.
Charvet
“Once we got our partnership
with CEA-Leti up and running, we rapidly established
strong mutual trust. I was impressed with how fast and
flexible CEA-Leti and Clinatec were during the transfer
of the WIMAGINE® implant technology. Personally,
working with CEA-Leti has been very valuable to me as
a scientist. I am excited about the prospect of working
with CEA-Leti and Clinatec on future projects,” said
Lorach.
CEA-Leti will now be directing its efforts toward
developing AI-enabled low-power Edge signal processing
and advancing tighter integration architectures for more
compact implantable systems. Close collaboration with
clinical partners will ensure that clinical and regulatory
issues are addressed at every step of the technology
development process.
With a technology portfolio spanning microelectronics,
sensors, actuators, and more, CEA-Leti boasts over
350 active patents to protect the deployment of its
enabling technologies in health. CEA-Leti’s health-related
research involves all five of the institute’s departments and
the Clinatec biomedical research center, which has its own
clinical unit. Finally, CEA-Leti has an active partnership
strategy in support of its core mission of transferring new
technologies to partners, whether they are hospitals or
medical device manufacturers.
© Jimmy Ravier – EPFL / CHUV
© EPFL
06 I EMERGING DEVICES TO IMPROVE HUMAN HEALTH
A paraplegic patient regained a natural control of walking
thanks to the coupling of the WIMAGINE Brain Computer
Interface technology with a spinal cord stimulator.
Further reading
• Hamieh, S., Heiries, V., Al Osman, H., & Godin, C. (2023).
Relapse detection in patients with psychotic disorders using
unsupervised learning on smartwatch signals. In 2023 IEEE
International Conference on Acoustics, Speech and Signal
Processing (ICASSP) (pp. 1).
• Grangeat, P., Duval Comsa, M.-P., Koenig, A., & Phlypo, R.
(2023). Dynamic Modeling of Carbon Dioxide Transport through
the Skin Using a Capnometry Wristband. Sensors, 23, 6096.
• Lorach, H., et al. (2023). Walking naturally after spinal cord injury
using a brain–spine interface. Nature, 618(7963):126-133.
• Morvillier, R., Prat, C., & Aloui, S. (2023). A camera-based
system to detect driver hands on the steering wheel in semiautonomous vehicles. In M.-R. Amini, S. Canu, A. Fischer, T.
Guns, P. Kralj Novak, & G. Tsoumakas (Eds.), Lecture Notes in
Computer Science: Machine Learning and Knowledge Discovery
in Databases (pp. 617-621). Cham: Springer Nature Switzerland.
89
SCIENTIFIC
REPORT
2023
What organs-on-chips can do:
•
•
•
•
90
Reduce animal testing by
providing an in vitro alternative
that more closely mirrors in vivo
human organs
Enable personalized medicine
and lessen side effects, like by
testing treatments on a replica
of an individual patient’s tissue
from biopsy
Enable regenerative tissue
therapies and post-organtransplant therapies
Safely test and screen new
therapeutic modalities
Fabrice Navarro
© CEA
Organon-chips
© UtopikPhoto / CEA
© CEA
Organs-on-chips, or
microphysiological systems, are
microfabricated devices with
tightly controlled parameters
designed to mimic the in vivo
functioning of human tissues
in vitro. These tiny systems
are made from microfluidic
chips that contain the 3D living
systems of interest to deliver
essential nutrients and maintain
physiological conditions. Organson-chips provide a more realistic
testing ground than 2D cells
cultivated on plastic substrates,
and could be a relevant
alternative to animal testing
in the near future. CEA-Leti
is leading the way in the next
generation of organ-on-chip
research and development.
© UtopikPhoto / CEA
ORGANS-ON-CHIPS
SUPPORT SAFER,
MORE PERSONALIZED
MEDICINE
Frédéric Bottausci Pascal Mailley
CEA-Leti draws on a portfolio of more than 50 patents for
microfluidic systems, including ten for organ-on-chip technologies.
And, with its own state-of-the-art cleanrooms and platforms, the
institute can design and fabricate the microfluidic components,
biocompatible materials, advanced sensors, and lensless imaging
systems that make up organs-on-chips.
Our research spans the growth and vascularization of organoids
on microfluidic chips, the study of organoid functionality using
purpose-built sensors, organ-on-chip monitoring using advanced
lensless imaging, and algorithms.
We made several notable advances in 2023. We achieved excellent
results with the design and fabrication of a novel biocompatible
impedance spectroscopy device that was assessed in vitro using
human airway epithelial cell cultures that could help improve the
development of organs-on-chips. Progress was also made toward
removing some of the obstacles to islet transplantation (IT) as a cure
for diabetes, a disease that affects more than 500 million adults
worldwide.
Advances in non-destructive
cellular functional integrity
screening for better organs-on-chip
Electrochemical impedance spectroscopy (EIS) is
widely accepted as an effective and nondestructive
method to assess cell health during cell culture.
Real-time monitoring of certain cell health parameters
using EIS could also assist in the development of
better organ-on-chip platforms for in vitro testing.
However, because the technique has never been
integrated into an automated system, it is difficult to
implement in large-scale screening. A recent advance
at CEA-Leti could change that.
© MP Studio - Adobe Stock
06 I EMERGING DEVICES TO IMPROVE HUMAN HEALTH
Lung epithelial cells a relevant organ-on-chip
test case
Organs-on-chips are well-suited for the study of lung
epithelial cell permeability. The cells are frequently
exposed to airborne insults from a variety of sources,
resulting in changes in cell health. Animal models,
traditionally used for risk assessment and biocompatibility
testing, pose ethical concerns, are labor-intensive,
expensive, and do not fully extrapolate to human
conditions. New in vitro models and testing platforms
like organs-on-chips would eliminate the need for animal
models.
Material and design optimizations lead
to a novel EIS system
In this research, we fabricated a device using easyto-manufacture processes like screen printing (of the
impedance electrodes) and molding and micromachining
(of the cell culture chamber). The electrode inks were
optimized to be biocompatible and sterilizable, and
three variations of the electrode design were tested to
measure their impact on impedance sensor response. The
goal was to accurately measure transepithelial electrical
resistance (TEER) as a surrogate for barrier tissue integrity
and to round out this mono-frequential measurement with
spectroscopic data over a wide range of frequencies.
Integration with a microfluidic chip containing
epithelial cells
The complete organ-on-chip system with cell-culture
chamber and impedance spectroscopy electrodes is
compatible with cell-culture conditions and facilitates
real-time TEER measurements for monitoring cell growth
and barrier tissue integrity. It could also be used to assess
cell stress in biomaterial risk assessments, complementing
the detection of inflammatory metabolites using
multiparametric electrochemical sensing platforms. The
chosen inks and processes are also cost-effective and
manufacturable.
Islet transplantation could
give diabetes patients new hope
Diabetes is a major global public health
issue. Current treatment methods, such as
intensive insulin therapy, have not provided
a permanent solution for insulin-dependent
diabetes. Pancreas transplantation (PT) and
islet transplantation (IT) are available options
but come with significant drawbacks. CEA-Leti
is working on organ-on-chip technologies that
could improve IT performance and, ultimately,
give patients with diabetes hope for a better
cure.
Islet transplantation could succeed when pancreas
transplantation is not an option
Pancreas transplantation is extremely limited by organ
availability. Islet transplantation—islets are “islets of
Langerhans,” the pancreatic cells that secrete insulin—
overcomes this hurdle, but is not without its own
challenges, including lifelong immunosuppression and
limited duration of efficacy. Our research is addressing
these concerns.
Innovations in islet encapsulation for improved IT
The development of methods to eliminate chronic
immunosuppression and enhance the 3D islet niche for
better functionality and longevity are crucial to improving
IT. One approach is to create capsules from concentrated
polymer solutions. This increases mechanical strength
and stability and results in smaller pores for better
immunoprotection. However, producing capsules that can
maintain regular shapes and high polymer concentrations
has been a challenge.
A "soft landing" for more robust encapsulation
At CEA-Leti, we introduced a groundbreaking soft landing
technique into centrifugal microencapsulation, successfully
producing monodisperse ellipsoidal capsules containing
cells from highly viscous alginate solutions. This method,
applicable to various centrifugal devices, has shown
potential in using soft landing liquids like soybean oil,
silicone oil, and n-Decane liquid for producing consistent
capsules. This advance not only holds promise for diabetes
cell therapy, but also extends to broader applications
like organoid production and medical delivery, marking
a significant step forward in managing—and possibly
curing—diabetes.
Further reading
• Cl. Quintard, et al. A microfluidic platform integrating functional
vascularized organoids-on-chip. Nature communications, 2024.
• Badalan, M., et al. A Soft Landing Approach for the Centrifugal
Microgel Synthesis Process. Comptes Rendus. Mécanique,
351, 83-102, 2023.
• Badalan, M., et al. Physical Analysis of the Centrifugal
Microencapsulation Process. Industrial and Engineering
Chemistry Research, 61, 10891-10914, 2022.
• Badalan, M., et al. Three-Dimensional Phase Diagram for
the Centrifugal Calcium-Alginate Microcapsules Production
Technology. Colloids and Surfaces A: Physicochemical and
Enginnering Aspects, 635, 127907, 2022.
• Chmayssem, A., et al. New Microfluidic System for
Electrochemical Impedance Spectroscopy Assessment
of Cell Culture Performance: Design and Development
of New Electrode Material. Biosensors, 12, 452. 2022.
doi.org/10.3390/bios12070452.
91
SCIENTIFIC
REPORT
2023
Toward biocompatible printed electronics
for transient, bioresorbable medical devices
© Chr. Morel / CEA
CEA-Leti research
engineer
Advances in printed electronics
are driving innovations in the
biomedical arena, where flexible,
stretchable electronics that
can conform to the structures
found in human tissues could
soon give rise to new resorbable
electronic biointerfaces that
disappear after use. CEA-Leti
and partners prototyped a
fully-organic, resorbable, crosslinkable, ink-jet-printable ink for
transient biomedical devices with
applications in monitoring, tissue
stimulation, and drug delivery.
Toward safe, functional, and comfortable biomedical devices
Conductive hydrogels have the potential to be used as contact electrodes
in transient, resorbable biomedical devices. Natural polysaccharides
like hyaluronic acid and heparin, used in combination with organic
conductive polymers, are potentially attractive building blocks for these
future devices. So far, however, little research has been reported on
chemically-crosslinked polysaccharide hydrogels that incorporate a
conducting polymer and exhibit mechanical properties similar to the
native extracellular matrix of interest. Additionally, most of the conductingpolymer hydrogels in the literature have synthetic polymer backbones. We
decided to fill this gap with a new approach.
A resorbable conductive fully organic ink made ofmodified hyaluronic
acid (HA) and PEDOT conductive polymer is printed on a resorbable
bioplastic PLGA substrate and UV-cross-linked to design a prototype
that resorbs in a fewweeks when immersed in aqueous fluid.
© CEA
Isabelle Texier
Impact
A fully-organic, resorbable, crosslinkable, ink-jet-printable ink was
successfully implemented in a
resorbable bioelectronic device. This
major advance could open the door to
flexible, stretchable drug delivery, tissue
stimulation, and monitoring devices
that dissolve when they have finished
performing their function.
Research partners
CEA-Leti, the Clinatec biomedical research
center, and CERMAV-CNRS.
Further reading
• LLeprince, M., et al. Design of hyaluronan-based
dopant for conductive and resorbable PEDOT ink.
Carbohydrate Polymers, 301(Part B), 120345. ISSN
0144-8617. 2023.
• Leprince, M., et al. A cross-linkable and resorbable
PEDOT-based ink using a hyaluronic acid derivative
as dopant for flexible bioelectronics devices.
Materials Advances, 4, 3636-3644. 2023.
doi: 10.1039/d3ma00170a.
92
A new class of biopolymer-based resorbable biocompatible
electrodes
The objective of this research was to design and prototype a biopolymerbased resorbable electrode array with sensing capabilities. The chosen
design was an organic printed electrical track and contact electrode
embedded in a biocompatible insulating material. The inks were made
of water-borne dispersions of PEDOT conducting polymer-sulfated
polysaccharide inks specially formulated to achieve the best tradeoff
between conductivity, printability, and controllable biological degradation.
New ink formulations implemented in prototype
To the best of our knowledge, the introduction of aromatic moieties
on polysaccharides to design new PEDOT biodopants has never been
described in the literature. Our research showed that modifying the
polysaccharide backbone with both sulfonic and conductive moieties
resulted in high ink conductivity in physiological conditions. The
resorbability of this new conductive material will allow the fabrication of
fully resorbable bioelectronic interfaces to address innovative medical
applications. The research resulted in one patent, two papers accepted for
publication (with CEA-Leti PhD student Maxime Leprince as first author),
and a third paper underway.
06 I EMERGING DEVICES TO IMPROVE HUMAN HEALTH
3D time-lapse imaging could bring
advanced pre-implantation embryo
observation to IVF clinics
Lionel Hervé
© CEA
CEA-Leti research engineer
Infertility affects some one in seven couples worldwide. IVF, a procedure
performed millions of times each year, depends in part on medical imaging,
used to select the most viable embryos for implantation. CEA-Leti helped
develop a compact new microscope that acquires three-dimensional timelapse images of living embryos directly in a cell culture incubator. The
technology could boost IVF pregnancy rates.
Leveraging pre-implantation embryo imaging to
increase the chances of successful IVF
Despite the routine nature of pre-implantation embryo
imaging procedures in tens of thousands of IVF clinics
worldwide, little attention has been paid to how better
imaging could contribute to more effective embryo
selection and, as a result, higher pregnancy rates.
CEA-Leti and partners have developed a new microscope
that enables the direct observation of embryonic
development from the moment of in vitro fertilization up
to six days post-fertilization.
A complex imaging system with strict
specifications
© CEA
Multiple constraints were considered in the microscope’s
design, starting with the system’s optical characteristics.
For effective observation of embryos, an excellent
tradeoff between field of view and resolution had to be
reached. In addition, the process had to be free from
toxic fluorescent substances or stains and non-intrusive
to protect embryos from harm. Ease of use in incubator
conditions and compatibility with the demands of a
biological analysis lab
were also factored
in. In terms of the
output, the 3D image
reconstruction had to be
computationally efficient
and the final rendering
useful to physicians in
terms of the quality
of the information
provided.
The compact 3D microscope developed has a LED
array (top) providing various angles of illumination
for the acquisition and 3D rendering of the sample.
Advanced 3D reconstruction software the system’s
cornerstone
A crucial component of this system is the software, which
converts raw data into 3D volumes. For the first time
ever, a neural network was implemented to complete the
necessary computations and provide extremely detailed
3D renderings. So far, the microscope has been tested
on mouse embryos, and the results are promising. The
3D time-lapse images produced allowed embryologists
to analyze the developing embryos’ morphological and
kinetic features—information that could open the door to
the use of novel markers for pre-implantation embryonic
health, contributing to the broader goal of improving IVF
success rates. CEA-Leti PhD candidate William Pierré was
first author of a paper on the microscope published in
Applied Optics.
Impact
Pre-implantation embryo observation must be as nonintrusive as possible. Our 3D microscope is particularly
effective—and gentle—at finding new embryonic
viability markers. This advance could help millions of
patients dealing with infertility.
Research partners
Several CEA departments, including at CEA-List;
Grenoble University Medical Center.
Further reading
• Pierré, W., et al. 3D time-lapse imaging of a mouse
embryo using intensity diffraction tomography embedded
inside a deep learning framework. Applied Optics, 61,
3337-3348. 2022.
93
SCIENTIFIC
REPORT
2023
New rapid bloodstream pathogen
identification technique for
faster diagnosis of infections
Early diagnosis of bloodstream
infections can make the difference
between life and death
© CEA
CEA-Leti engineer
Impact
Bloodstream infections are particularly
deadly, and rapid, accurate diagnosis
could make a huge difference in
outcomes for patients in septic shock.
E-MOC, an instrumented blood culture
bottle, could reduce time-to-results from
days to just hours.
E-MOC could make early diagnosis the norm
Research partners
94
© CE A
N/A
• Babin, T. Développement de capteurs
électrochimiques pour le diagnostic des
infections sanguines. PhD Dissertation,
Université Grenoble Alpes. 2023.
• Babin, T. C., et al. Electrochemical labelfree pathogen identification for bloodstream
infections diagnosis: Towards a machine
learning based smart blood culture bottle.
Sensors and Actuators B: Chemical,
387, 133748. onic devices. Materials
Advances, 4, 3636-3644. 2023.
doi: 10.21203/rs.3.rs-2153621/v1.
E-MOC prototype and,
for a blood sample
infected with E. coli,
readings of electrical
potentials over time
on the nine electrodes.
Given the potential outcome of bloodstream
infections—septic shock and, ultimately,
death—rapidly identifying the pathogen
responsible is crucial. The statistics speak
for themselves: In 2017, 48.9 million cases of sepsis and 11 million deaths
accounted for 19.7% of total worldwide mortality. The numbers are
just as dire for individual patients, with mortality rates rising by 7.6%
for every hour of ineffective treatment during septic shock. Alarmingly,
the diagnostic process, from blood sampling to the decision of what
antimicrobial treatment to administer based on test results, takes over
35 hours on average. Rapid testing solutions for the early and accurate
diagnosis of these infections could save many, many lives.
Pierre Marcoux
Further reading
© CEA
E-MOC is a revolutionary smart blood culture bottle based on
an innovative CEA-Leti technology. The purpose of the device is
to bridge the current gap in the early diagnosis of bloodstream
infections, notorious for their high morbidity and mortality
rates. A startup is planned to further develop and, ultimately,
commercialize E-MOC.
While there have been advances in rapidly identifying pathogens and
testing for antibiotic susceptibility after a blood bottle is flagged as
positive, low-cost solutions addressing the early stages of the process
to speed up total time-to-result have been sorely lacking. The E-MOC
smart blood culture bottle addresses this gap by taking advantage
of the time traditionally wasted during the transportation of blood
bottles. Equipped with multiple electrodes, the bottles have their own
tiny, artificial-intelligence-enabled multiparametric electrochemical
monitoring systems so that bacteria can be
detected and identified during transportation
of the sample, saving precious time.
Monomicrobial infections were successfully
diagnosed, with no false positives or negatives
Thibaut
so far, thanks to each cultured pathogen’s
Babin
unique fingerprint. No reagents or further
sample preparation steps were required.
The research won
CEA-Leti PhD Thibaut
Babin (see below) a Best
Dissertation Award from
the French Microbiology
Society.
Concept proven; clinical trials next
The technology has been proven, and a
path toward integrating the electrodes into
blood bottles to form a manufacturable
fully-instrumented consumable will now need
to be mapped out. For regions with limited
resources, efforts are underway to produce a cost-effective consumable
made from paper and affordable inks. A planned startup could pursue the
development of this groundbreaking solution and bring it to the market.
06 I EMERGING DEVICES TO IMPROVE HUMAN HEALTH
Unprecedented phage surface density
could help advance phage therapy and
enable new antibacterial surfaces
© CEA
© CEA
A novel functionalized surface for rapid phage
screening
Pierre Marcoux
CEA-Leti engineer
Larry O’Connell
CEA-Leti PhD candidate
With the increase in antibiotic-resistant
bacteria, scientists are investigating solutions
like rapid testing for faster treatment of
infections and functionalized antibacterial
surfaces to control bacteria before they
cause harm. CEA-Leti’s groundbreaking
research brings the latest advances in
biophotonics and surface chemistry to
tomorrow’s phage therapy.
Phage therapy an area of increasing interest
against multi-drug-resistant bacteria
© L. O’Connell / CEA
By 2050, antibiotic-resistant infections could claim 10 million
lives annually. Phage therapy, which uses bacteriophages,
or bacterial viruses, to combat bacterial infections, stands
out among the potential solutions. The therapy’s success,
however, hinges on effective targeting of highly specific
phages and ensuring the stability of complex pre-assembled
phage cocktails. Understanding the complex interplay
between phages and bacteria and the ability to rapidly
select the right phage or
combination of phages
for individual patients will
be paramount. CEA-Leti
is developing a disruptive
interdisciplinary
methodology at
the intersection
of biophotonic
microsystems and surface
chemistry to enable the
kind of in-depth analysis
of phage-bacteria
interaction required for
modern phage therapy.
Bacteriophage gh-1 grafted on a gold surface.
The ability to select the most active phages very rapidly
from phage banks is vital to the timely treatment of
antibiotic-resistant infections. Our goal was to produce
a multiplexed surface plasmon resonance (SPR)
screening method enabling rapid identification of the
ideal bacteriophages for individualized therapy. We
prototyped an innovative method for locally immobilizing
bacteriophage monolayers on a gold surface to multiplex
phage susceptibility testing on the surface. bacteria are
injected into a microfluidic flow that interacts with this
functionalized surface, producing a detectable SPR signal
used to identify the desired phage.
Study of immobilization chemistries produces new
information about gold surfaces
Although the chemical immobilization of phages on gold is
a crucial aspect of SPR-based tests, different immobilization
chemistries and the immobilization of multiple phages
with the same parameters have rarely been studied. Our
comparison revealed that a bacteriophage-functionalized
gold layer can easily approach the geometric limits of
surface density when cross-linked to the surface with
11-merceptoundecanoic acid if special consideration is paid
to upstream purification of the phage suspensions. In this
research, we obtained an unprecedented surface density
of grafted phages approaching the theoretical geometric
density limit.
Impact
These advances could help bring phage-functionalized
antimicrobial surfaces to hospitals and other settings and
enable rapid multiplexed phage susceptibility testing.
Research partners
IRIG – SYMMES with the support of LABEX ARCANE
and CBH-EUR-GS (Grant ANR-17-EURE-0003).
Further reading
• O’Connell, L., et al. Approaching the Geometric Limit
of Bacteriophage Conjugation to Gold: Synergy of
Purification with Covalent and Physisorption Strategies.
ACS Biomaterials Science & Engineering, 9(5), 2335–2346.
2023.
• O’Connell, L., et al. Rapid fabrication of interdigitated
electrodes by laser ablation with application to
electrokinetically enhanced surface plasmon resonance
imaging. Optics & Laser Technology, 161, 109167. 2023.
95
New technique detects
lethargic but still-infectious
pathogens for safer seafood
Seafood is responsible for a non-negligible proportion
of the collective food poisoning outbreaks that occur
each year. A new technology developed by CEA-Leti and
partners will make it possible to analyze the surfaces of
seafood packaging plants, identifying pathogenic bacteria
that are lethargic but still potentially infectious.
© ThomasBrauge & Graziella Midelet (ANSES).
SCIENTIFIC
REPORT
2023
Raman microspectrometer
at ANSES food safety
lab. The microscope plus
Raman spectrometer can
chemically analyze a single
bacterial cell (1 µm).
© CEA
VBNC bacteria a silent threat
Pierre Marcoux
CEA-Leti engineer
Impact
This new detection technology will make
it possible to test the surfaces of seafood
packaging plants for pathogenic bacteria
that are lethargic but still infectious,
mitigating a significant, yet silent, food
poisoning risk.
Research partners
ANSES (Raman microspectroscopy),
INRAE (application of the method
to a new Vibrio strain).
Further reading
• Trigueros S., et al. Deuterium isotope probing
(DIP) on Listeria innocua: Optimisation of
labelling and impact on viability state.
PLoS ONE 18(3): e0280885. 2023.
doi.org/10.1371/journal.pone.0280885
• Trigueros S. Mesure du métabolisme par
microspectroscopie Raman : Application à la
détection des cellules viables non cultivables de
Listeria. Sciences agricoles Université du Littoral
Côte d’Opale, 2022.
96
Many of the processes present in seafood manufacturing plants—salting,
smoking, marinating, chilling, cleaning, and disinfection—can drive
bacterial pathogens into what is known as a viable but non-culturable
(VBNC) state that makes them undetectable using conventional testing
techniques. These dormant pathogens can once again become harmful
once they are exposed to more favorable conditions, like those in
the human digestive tract, effectively “waking up” once ingested. A
2021 report by the European Food Safety Authority pointed to listeriosis,
which, caused by Listeria bacteria, had a mortality rate of 17.6% in 2019.
Because of the particularly severe consequences of Listeria contamination,
we decided to address it in our research, using Listeria innocua as a model
for Raman microspectroscopy-based VBNC detection.
Raman-DIP, a novel combination detection method
We began with Raman spectroscopy, known for its rapid, label-free,
single-cell identification capabilities. We then looked at how to best
couple it with Deuterium Isotope Probing (DIP), a technique that uses
heavy water (D2O) to measure metabolic activity. Together, the two
techniques turned out to be a cost-effective, non-destructive means
of detection. D2O had previously been shown to disrupt metabolic
pathways, impeding growth and biofilm formation. Therefore, we
looked at the impact of D2O on L. innocua cells in three states:
viable culturable, viable but non-culturable, and dead. Our Raman
spectroscopy studies confirmed that D2O did not affect the viability
of L. innocua. We also improved the DIP labelling protocol, achieving
maximum labelling intensity after two hours of exposure to 75% v/v
D2O. Early detection (at one and a half hours) was also possible.
This innovation indicates that Raman-DIP is a viable foundation
for developing new methods for detecting metabolically active
Listeria cells. CEA-Leti won two Best Poster Awards at the 2021 and
2022 French Microbiology Society Congresses for this research.
Helping public health authorities improve food safety
French food safety authority ANSES began working on pathogen
detection with CEA-Leti in 2018. A Raman spectrometer with singlebacteria resolution was acquired by the CEA and, in 2022, made
available to ANSES for bacterial pathogen detection in seafood. In
2023, the partnership expanded to include national agronomy research
institute INRAE. The implications just for France, as the 4th largest
fishery and aquaculture producer in the EU, are significant.
06 I EMERGING DEVICES TO IMPROVE HUMAN HEALTH
© CEA
© Marine Beurrier-Bousquet
Cancer screening and environmental
microplastics detection could benefit
from a label-free MIR interferometric
imaging technique
Marine Beurrier-Bousquet
CEA-Leti PhD candidate
A PhD dissertation recently completed at
CEA-Leti demonstrated the effectiveness
of a novel technique that could transform
in vivo cancer screening and the detection
of microplastics in water by eliminating the
need to dehydrate samples for chemical
analysis. The CEA’s quantum cascade laser
and uncooled infrared detector expertise
were instrumental in this advance.
New devices enable new imaging methods
Fourier transform infrared spectroscopy (FTIR) stands as
a reference technique for chemical analysis. However,
absorption by water at infrared wavelengths makes spectral
measurements on hydrated samples nearly impossible.
The emergence of new devices like quantum cascade
lasers (QCLs) and uncooled infrared imagers have opened
new avenues toward obtaining spatially resolved spectral
information in the infrared range on non-dehydrated
samples. This PhD research explored the potential of these
techniques to overcome the challenges posed by water
absorption.
Interferometric test bench
in the mid infrared.
Up next, testing on cancerous tumor samples
To our knowledge, this is the first time infrared images of
samples immersed in water have been generated using
holography. The next step will be to test the technique on
actual samples of hydrated cancerous tissue. In terms of
miniaturization and integration into a future medical device
like an endoscope, additional research and development will
also be needed.
Impact
Together, quantum cascade lasers, uncooled IR
detectors, and digital holography can effectively
analyze the chemical composition of aqueous samples,
creating a new path to applications like in vivo medical
diagnostics and environmental monitoring.
Digital holography a promising solution
Digital holography, operating on the principles of
interferometry, offers a promising solution for analyzing
hydrated samples in the mid-infrared spectrum. Here’s how
it works: A laser beam is bifurcated and then recombined,
with the sample placed in one beam and a reference
sample in the other. The difference in the two beams after
passing through the samples can be measured when the
beams are recombined. QCLs are powerful enough to pass
through the water in the samples, and holography allows for
measurements that are sensitive to the sample’s refractive
index and, therefore, its spectral signature, despite water
absorption. Finally, the uncooled infrared detectors generate
the resulting image—the hologram.
Research partners
N/A
Further reading
• Beurrier-Bousquet, M., et al. Mid-infrared digital
holography imaging in aqueous media. Proceedings
of SPIE, Label-free Biomedical Imaging and Sensing
(LBIS), 12391, 1239108. 2023.
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MARKET
NEWS
© A. Aubert / CEA
FROM OUR R&D PARTNERS
HEALTH PLATFORM
Innovation is the key to success in today’s fast-paced medtech industry.
Having the right R&D partner can be a real advantage.
MedTech companies, from startups to multinationals, can leverage CEA-Leti’s R&D
capabilities at every stage of their product development process: from early-stage
R&D to manufacturing. This could ensure regulation-compliant development and
clinical testing for new medicaldevices.
https://urlz.fr/nHOm
HOW CAN WE PREVENT BACTERIA
FROM SETTLING AND PROLIFERATING
ON THE INSIDE SURFACES OF THE
INTERNATIONAL SPACE STATION (ISS) ?
© NASA
Since 2016, CEA-Leti has been collaborating with Laurence Lemelle
and Christophe Place (ENS Lyon) to solve this challenge as part
of the Matiss project, which is funded by CNES.
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https://urlz.fr/nLM6
© ImageFlow / IRStone - Adobe Stock
06 I EMERGING DEVICES TO IMPROVE HUMAN HEALTH
INJECTSENSE,
A START-UP THAT GIVES HOPE
TO GLAUCOMA SUFFERERS
Source : France Bleu Isère
Gérard Fourgeaud.
Tuesday, June 27, 2023.
© vicu9 - Fotolia.com
It’s a start-up that could revolutionize
the cure for glaucoma: a terrible eye
disease that can lead to blindness.
"Injectsense" is on show at the "Leti
innovation Days" until Thursday June
29, at Minatech in Grenoble.
https://urlz.fr/nWow
www.injectsense.com
Published on 12 January 2022.
The problem with implantable medical monitoring devices for organs
like the eye, brain, or heart, is that the power sources are often larger
than the actual sensors.
Startup Injectpower was founded in early 2020 to tackle this challenge.
The company is building on a technology protected by 40 CEA-Liten
and CEA-Leti patents to offer rechargeable millimeter-sized microbatteries.
These tiny batteries make on-demand, intervention-free,
in situ measurement possible.
© Injectpower
INJECTPOWER, FOR IMPLANTABLE
MONITORING DEVICES THAT LAST
https://urlz.fr/nWBz
www.injectpwr.com
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MARKET
NEWS
FROM OUR R&D PARTNERS
ADMIR
HOW CEA SPIN-OFF ADMIR PLANS TO CUT CANCER
DIAGNOSIS TIME BY A FACTOR OF 100
© UtopikPhoto / CEA
© UtopikPhoto / CEA
© ADMIR
Source: Usine Nouvelle
January 2023.
A new start-up incubated at the CEA, Admir
aims to shake up the field of medical analysis.
At CES 2023, the deeptech company is
presenting an imaging system designed for
laboratories and hospitals. Using infrared
technology, the company claims to be able to
dramatically reduce cancer diagnosis times.
Mathieu Dupoy
CTO
Laurent Duraffourg
CE
The prototype machine
from start-up Admir
measures around
50 centimetres.
Laurent Duraffourg,
Admir’s CEO, said:
“With current equipment, cancer analysis can take two days
to three weeks. The system is completely clogged up as the
number of examinations increases exponentially. Our device
can reduce this analysis time to one hour.“
https://urlz.fr/nHX0
www.admir-analysis.com
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06 I EMERGING DEVICES TO IMPROVE HUMAN HEALTH
ECLYPIA, THE NEW STARTUP WORKING ON A LOW-COST,
NON-INVASIVE BLOOD GLUCOSE-SENSOR
By pooling their know-how, Eclypia and CEA-Leti
have developed an optimized, low-cost quantum
cascade laser (QCL) manufacturing process that
uses silicon as a production vehicle, bringing QCLs
into the field of silicon photonics.
© Eclypia
© Eclypia
Hélène Lefebvre, General Manager
and Jean-Guillaume Coutard, CTO
Jean-René Lequepeys,
CEA-Leti CTO, said:
“Based on our expertise in integrated photonics
and microelectronics processes, CEA-Leti is
mobilizing its teams to support the development
of a low-cost, non-invasive blood glucose sensor,
in close collaboration with Eclypia’s teams.“
https://urlz.fr/nHNo
www.eclypia.com
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MARKET
NEWS
FROM OUR R&D PARTNERS
MAG4HEALTH RAISES
5.3 M€ IN FINANCING
© Mag4Health
Source: La Région Auvergne-Rhône-Alpes Entreprises
Published June 9, 2023.
The Grenoble-based start-up that maps the inside of the brain has
raised €5.3 million from Business Angels, family offices, Bpifrance,
the Auvergne-Rhône-Alpes Region and ANR.
https://urlz.fr/o3qe
www.mag4health.com
102
From left to right:
Agustin Palacios-Laloy,
Jaroslaw Rutkowski, Matthieu
Le Prado, Rudy Romain,
Guillemette Barier, Etienne
Labyt, Sergey Mitryukovskiy.
06 I EMERGING DEVICES TO IMPROVE HUMAN HEALTH
103
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AWARDS
Award-winning research by scientists of all ranks
emblematic of CEA-Leti’s culture of collaboration
in support of scientific excellence
© CEA
104
The European Microelectronics and
Packaging Conference® 2023 (EMPC®
2023) was a win for Auriane DespaxFerreres, a PhD student researching
materials at CEA-Liten, and for CEA-Leti
PhD student Julie Gougeon. DespaxFerreres received a Highly Commended
recognition for her oral presentation on
the development of a stretchable and
removable electrical interconnect solution
for ultra-thin electronic components.
Gougeon was honored with a Best Paper
Award for her outstanding paper titled
“Development and Characterization of Fine
Pitch Flip-chip Interconnection Using Silver
Sintering.”
Justine Lespiaux and Marvin Frauenrath
were awarded the Best Student
Presentation award at the 242nd ECS
(Electrochemical Society) Meeting
in 2022 for their outstanding research
in semiconductor materials and
photodiode technology. Lespiaux’s
research, on the epitaxial growth of
IV-IV semiconductor materials, probed
the materials’ growth characteristics and
incorporation of dopants, providing fresh
insights into their properties and uncovering
potential new applications. Lespiaux, committed
to environmental sustainability in her personal
life and her research, plans to integrate her
findings into devices to enhance energy
efficiency. Frauenrath tackled the integration
of innovative materials with standard industry
equipment using reduced pressure-chemical
vapor deposition (RP-CVD). He achieved a
breakthrough by reducing contact resistance
through strong doping levels and enhancing
electrical confinement in the manufacture of
SiGeSn photodiodes, which exhibited superior
light-emitting intensity to those with doped
Ge contact layers. The devices could be used
for gas detection and as CMOS-compatible
components. Frauenrath’s next objective is
to create an electrically-powered laser that
functions under similar conditions.
EA
©C
EA
©C
© L. Termeau
/C
EA
CEA-Leti PhD students were very active
in materials and packaging in 2022-2023,
bringing home a number of awards
Anthony Albanese won the
Best Poster Presentation
award at E\PCOS 2022, the
European Phase-Change
and Ovonic Symposium, held
in September 2022 in Oxford,
for his research on amorphous
chalcogenide materials. His awardwinning poster demonstrates CEA-Leti’s
leadership in innovative photonic solutions.
Albanese’s research could support advances
in quantum computing, infrared sensors,
and telecommunications.
AWARDS
CEA
CE
A
Dudes Photo /
o
Tw
©
©
©
Camille Laguna, now a process
integration engineer for advanced
phase change memory at
STMicroelectronics, won a
Best Student Paper Award
at the ESSDERC 2022 - IEEE
52nd European Solid-State Device
Research Conference for her paper entitled
“Multilayer Structure in SeAsGeSi-based
OTS for High Thermal Stability and Reliability
Enhancement.” She compared the multilayer
OTS with a SeAsGeSi-based bulk alloy,
demonstrating the multilayer material’s
superior thermal stability, reduced deviceto-device variability, and reliable switching
operations at temperatures up to 300 °C.
given by a Student Merit Award winner at the
American Vacuum Society International
Symposium. Ronco won the award for his
research on process drift of SiO2 atomic layer
etching in HFC and FC/Ar chemistries by optical
spectroscopy and surface chemistry analysis.
Kyllian Millard won a Best Poster
Award at JNOG (Journées
Nationales d’Optique Guidée)
2023, a major French optics
meeting. Alain Aspect, winner
of the Nobel Prize in Physics
2022, presented the award.
Milliard is studying integrated
photonics, with a focus on designing and
characterizing photonic integrated circuits (PICs)
on transparent substrates for near-eye displays
that could be integrated into solutions like
augmented reality glasses.
Raphaël Feougier received the
Intel Supply Chain Best Student
Award at 2023 SPIE Advanced
Lithography + Patterning
in San Jose for his innovative
paper on grayscale lithography
for the creation of anti-reflective
nanostructures that could boost the
light-collecting properties of surfaces in
dark environments and enable self-cleaning
capabilities for devices like solar panels and
imagers. Feougier found his inspiration
for the advance in insect eyes.
Antoine Ronco won the 2023 PSTD
Coburn & Winters Student Merit Award,
which recognizes outstanding research
achievements and an oral presentation
© CEA
r.
Ch
Mo
rel / CEA
Process, integration, and device
research also earned our PhD students
awards in 2022-2023
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Théo Ayral earned a spot among the finalists
for Best Student Paper at the 2023 IEEE/
ASME International Conference on
Advanced Intelligent Mechatronics
(AIM Seattle 2023) for a tactile-based
method for detecting slippage in
robotic manipulation utilizing a single
piezoelectric sensor. This novel approach
combines spectral analysis and deep learning
to enhance efficiency and adaptability. The
award-winning research featured an automated
data collection process with accurate and
unbiased labels for slip events. This innovative
technique has significant potential to improve
the performance and reliability of robotic
systems, particularly in grasping applications.
EA
©C
Simone d’Agostino won a Second Place
Best Paper Award at the 5th International
Conference on Artificial Intelligence
Circuits and Systems (AICAS 2023)
for his research on artificial intelligence
and neural networks. The awardwining paper focused on optimizing
the implementation of metaplasticity in
quantized neural networks, a key element for
long-term memory emulation.
CEA-Leti PhD students also brought
home awards for their research for
telecommunications and space applications
© CE A
EA
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EA
©C
Artificial intelligence research
won CEA-Leti PhD students two awards
106
Ibrahim Sbeity received the
Best Paper Award at the
2023 International Conference
on Localization and GNSS
(ICL-GNSS) held in Spain. His
award-winning paper, titled
“RNN-Based GNSS Positioning
using Satellite Measurement Features and
Pseudorange Residuals,” showcases innovative
research in the field of satellite navigation and
localization leveraging recurrent neural networks
(RNN) to enhance global navigation satellite
system (GNSS) positioning.
Marwan Jadid was recognized
with an Honorable Mention
for the Best Student Paper at
ISAP’22, the 2022 International
Symposium on Antennas and
Propagation, held in Australia
form October 31 to November 3,
2022. As the New Space market grows, new,
more compact high-performance antennas will
be needed. Jadid’s paper highlighted innovative
RF solutions that led to exceptional performance
with a non-conventional antenna size, an
advance that could reduce electromagnetic
pollution and space crowding.
Meanwhile, Jean-Michel Hartmann won
the Electronics and Photonics Division
Award at the 243rd Electrochemical
Society Conference in Boston in
May 2023. The award, established
in 1969, encourages excellence in
electronics research and recognizes
remarkable technical contributions in
electronics. Hartmann’s groundbreaking
research positions vertical germanium-tin
transistors as viable contenders for future
low-power, high-performance computing and,
potentially, quantum computing applications.
This significant breakthrough also led to a
publication in Nature and celebrated the longstanding partnership between Hartmann and
the Forschungszentrum Jülich research center,
a collaboration that has yielded over a hundred
joint publications since 2009.
pikPhoto / CE
Uto
topikPhoto / C
EA
In packaging-related research, Aurélia
Plihon was recognized with the
Outstanding Interactive Presentation
Paper award at the 2022 IEEE
72nd Electronic Components and
Technology Conference (ECTC)
in San Diego for her research on
advanced 3D packaging, a technology that
is crucial to IoT, AI, and medical applications.
In the research that won this award, she and
her team successfully obtained through mold
interconnections (TMIs) with an exceptional
height-to-pitch ratio. These results pave
the way toward high-aspect-ratio vertical
interconnects, opening new avenues for more
complex and higher-density integrations in
fan-out wafer-level packaging.
©U
© CE
A
© CE A
©
PhD students weren’t the only
CEA-Leti scientists who won awards
in 2023. Our senior researchers were
also well represented at leading
international conferences
A
AWARDS
Gaël Pillonnet, a seasoned
energy conversion expert at
CEA-Leti, won the First Place
of the Best Poster Award
at the Tuesday session of
PowerMEMS22 held in Salt
Lake City, Utah in December
2022 for his research on ultra-lowpower logic with contactless capacitive MEMS.
Pillonnet’s approach allows contactless MEMS
components to be used for logic computation.
By using adiabatic transformation during
information processing, it is possible to
achieve near-zero power consumption at lower
calculation frequencies. This breakthrough in
MEMS technology provides unprecedented
durability to the systems in which they are
integrated, making it a game changer in the field
of computing. What used to be impossible with
conventional approaches can now be imagined
with contactless MEMS.
CEA-Leti’s Scientific Director
Science Thomas Ernst was
elected to the Academy of
Europe (Academia Europaea)
in 2023 after being nominated
at the organization’s 34th
congress held on October 9 to
11, 2023 in Munich. Ernst believes
in mobilizing future generations to tackle
emerging issues in the vast adventure that
is technology research, a vision that reflects
CEA-Leti’s commitment to nurturing future
talent and fostering a vibrant ecosystem
conducive to sharing diverse perspectives on
global challenges. Academia Europaea is the
pan-European academy of sciences, humanities,
and letters. It was established in 1988 to
support excellence in scholarship. Its more than
5,000 members include leading experts from
a wide range of scientific and technological
disciplines.
107
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CONTACTS
Thomas Ernst
Alexei Tchelnokov
Jean-Paul Barnes
Viviane Cattin
Gaël Pillonnet
Pascal Mailley
VP for Science
and Technology
thomas.ernst@cea.fr
Scientific Advisor to the
Technology Platform Division
jean-paul.barnes@cea.fr
Scientific Advisor to the
Silicon Components Division
gael.pillonnet@cea.fr
Scientific Advisor to
the Optics and Photonics Division
alexei.tchelnokov@cea.fr
Scientific Advisor to the Smart Devices,
Telecommunications and Security Division
viviane.cattin@cea.fr
Scientific Advisor to the Technology
for Biology and Health Division
pascal.mailley@cea.fr
Abdelmadjid Hihi
Scientific Program Manager at Clinatec
abdelmadjid.hihi@cea.fr
108
MANAGING EDITOR:
Thomas Ernst
COPYWRITING AND EDITING:
Sara Freitas, SFM Traduction
COORDINATION:
Hélène Vatouyas, Viviane Cattin
DESIGN:
Design by Eve
COVER PHOTO:
P. Jayet / CEA
WITH ADDITIONAL CONTRIBUTIONS FROM:
Jean-Paul Barnes, Gaël Pillonnet, Alexei Tchelnokov,
Pascal Mailley, Abdelmadjid Hihi, Susana Bonnetier, Léa Di Cioccio
2023
Work performed in the frame
of the IRT Nanoelec
CEA-Leti is a member
of the Carnot Institutes network
17 avenue des Martyrs | 38054 Grenoble Cedex 9 | France
cea-leti.com
Research results presented in this document were achieved through a large number of projects, many of
which were financed by local, national, and European public institutions.
We therefore acknowledge and are deeply grateful for the support of the Auvergne- Rhône-Alpes region,
the Grenoble-Alpes Metropole, the Department of Isère, the French State (France 2030, National Research
Agency, “Plan de relance,” Bpifrance), and the European Commission (Horizon Europe, KDT Joint Unit).
@CEA-Leti
FRANCE
Supported by the French
Public Authorities within
the frame of France 2030
© CEA-Leti December 2023 - All rights reserved, any reproduction in whole or in part on any medium or use of the information contained herein is prohibited without the prior written consent of CEA.
© P. Jayet / CEA
SCIENTIFIC
REPORT