Contents of Technology Course
General observations:
The material is organized in modules. Each module treats a distinct part of device
fabrication. There is also an introduction (Module 1), a part that integrates the different
process techniques (Module 7), and a section where the limits of present technology and the
future of the electronic devices fabrication is presented (Module 8). Links exist between the
modules. Because it is tiresome and time consuming to open all the links and the windows
with definitions, etc., the possibility of accessing the material as a whole exists, especially for
printing purposes. Each module consists in a part for beginners/students with the basic and
most important things and a part addressed to specialists/scientists with more technical and
detailed descriptions.
The separation between the theory and exercises should be avoided. Simulations and
questions/problems are used to permanently challenge the student. They are be included (only
as a link) during the course presentation and also at the end of each module. Also links to the
theory are given as tips when solving a problem. The simulations have also explanations and
links to theory. Because technology is a more practical field the practical problems should
have great importance.
A great importance is given to the emerging technologies. Therefore, all the techniques
described have also a component called “the future of…”, which is positioned usually at the
end of the modules and the course.
Emphasize is put on comparing different techniques that have the same main goal; the
advantages and disadvantages of each of them is studied; the choice for the suitable technique
for a particular application/device is questioned/discussed. Important criteria for comparing
different equipments are the cost, the efficiency, the reproducibility and the reliability – all
these are critical for production and industry. For each technique, theoretical models, if
available, are given and explained; simulations based on models are compared with the
experimental results.
Three types of references will be added for each topic or example, if possible:
1. A book where explanations of the phenomena are explained in a more detailed and
simple form as for a beginner
2. A paper with more technical details (equipment, conditions) and where the newest
research results are presented
3. An internet reference with a group from a university or company that performs
research on the discussed subject; this can enable not only information gathering but
also possible contacts with the people working in the field
Contents:
Module 1. Introduction
 Course organization in modules and course objectives
 Overview of microelectronic devices
 a history of developments in electronic devices fabrication
 process overview (presentation of the basic process steps, clean room
protocols)
 device overview (presentation of material structure and properties, devices,
charge motion)
 Motivation – the importance of electronics (pictured examples of microelectronic
devices such as MOSFET, IC, MEMS, sensors and actuators, LED, photonic
crystals, MRAM) and the future of electronic device fabrication (rapidly emerging
technologies, nanotechnology)
Module 2. Semiconductor growth
 Theory of crystal structure
 Crystal preparation
 preparation methods: Czochralski and floating zones techniques
 methods of preparing the crystal surface, avoiding defects, obtaining a
specific purity by cleaning and gettering and the role of dopants
Module 3. Changing the doping and conductivity of materials
 Theory – conduction mechanisms in semiconductors; the relation between the
conductivity of semiconductor layers and the doping; the concept of sheet resistance
 Diffusion – definition of diffusion and diffusion constant, Fick’s laws, diffusion
models, enhanced diffusion; equipment for diffusion and measurement methods
 Ion implantation – definition of ion implantation, induced damage, channeling;
learning to model the process and to design “arbitrary” doping profiles; description
of equipment and measurement methods; annealing the defects (rapid thermal
annealing); advantages of ion implantation over diffusion
Module 4. Growing and depositing thin films
 Film parameters – that need to be monitored for each process: uniformity, purity, step
coverage, adhesion, deposition rate, defects, porosity, mechanical stress, chemical
bonds, electrical properties
 Oxidation and nitridation – chemical reactions and growth kinetics (Deal grove
model); LOCOS, description of equipment and detrimental role of impurities
 PVD
 Evaporation – description of process and different types of evaporation
(resistive heating, flash evaporation, arc evaporation, exploding-wire
technique, laser evaporation, rf heating, electron-bombardment heating)
 Sputtering – description of process and different types of sputtering (DC
sputtering, RF sputtering, DC/RF magnetron sputtering, collimated and
ionized sputtering, hot sputtering, reactive sputtering)
 metallization issues - resistivity, electromigration, planarity
 CVD – deposition kinetics and chemistry, vacuum systems and different regimes of
gas-flow
 different CVD methods (APCVD, LPCVD, atomic layer deposition)
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 PECVD – different types of plasma, study of plasma parameters influence
upon film parameters (selectivity, conformality, uniformity, damage)
Langmuir-Blodgett technique
Epitaxy of thin films – definition of epitaxial growth of crystalline solids, the different
growth stages, film nucleation, models for epitaxy
 applications: Si for advanced electronic devices, GaAs for optoelectronic
devices, quantum well engineering
 types of epitaxy: Liquid Phase Epitaxy (LPE), Metal-Organic Chemical
Vapor Deposition (MOCVD), Molecular Beam Epitaxy (MBE)
Future – ultra thin dielectrics, high k and low k dielectric, Al replaced by Cu, W-plug
Module 5. Defining patterns
 Lithography – patterning of the substrate via interaction of beams of photons or
particles with materials
 classification of resist materials upon their solubility after exposure
 mask fabrication
 optical sources and types of photolithography, dependence of resolution
upon exposure wavelength, dose energy and resist contrast
 advanced lithography for sub-100 nm region (X-ray lithography, electron
beam lithography, ion beam lithography), the resolution limit for each
technique and its application to particular device fabrication; the advantages
and disadvantages of each technique
 future: nanolithography micro-contact printing, nanoimprint lithography,
scanned probe lithography (carbon nanotubes as tips), dip-pen lithography
(AFM tip)
 Etching – the physical mechanisms, the etch figures-of-merit (etch rate, uniformity,
selectivity, anisotropy and undercut), different etching techniques:
 wet etching
 plasma assisted etching – various etch mechanisms in plasma (chemical,
physical, ion enhanced) and how to make one dominant; different plasma
etch systems (plasma, reactive ion etch, reactive ion beam etch & beam
milling) and the advantages and applications of each of them
 lift-off
 chemical mechanical polishing
Module 6. Materials and process characterization
 Thickness - ellipsometry
 Structure - orientation, defects and morphology of materials; characterization by
electron diffraction, X-ray diffraction, TEM, REM, X-ray fluorescence
 Composition – characterization by interactions with different particles/waves:
electrons, ions, photons, X-ray; main characterization methods: Auger, XPS, SIMS,
ERD, RBS
 Surface – Atomic Force Microscopy (AFM), comparison of different types of AFM:
constant force versus constant height, constant mode versus tapping mode
 In-situ measurements – Reflective High Energy Electron Diffraction (RHEED)
 Electrical measurements – for various test structures
 Future (nanocharacterization) – scanning probe microscopy
 AFM – by repulsion between outer electrons of tip and sample it can
perceive molecules and atoms and measure atomic forces; also magnetic and
capacitive force microscopy
 Scanning Tunnelling Microscopy (STM) – based on electron tunnelling
current between tip and sample due to quantum mechanical tunnelling, the
current is dependent on the distance; also possible atomic manipulation
 Ballistic Electron Emission Microscopy (BEEM)
 Near-Field Scanning Optical Microscopy (NSOM))
Module 7.
Integration of individual process steps to build semiconductor devices
and micro(nano)structures
 MOSFET / IC
 Magnetic transistor / MRAM
 Optoelectronic device (LED, photodetector)
 Sensor / MEMS
 Integrated system with everything on chip (optomechanical, sensor, CMOS and
magnetical)
 Simulation and practical work: Design, develop, fabricate and characterize a process
flow for a microstructure including materials and process characterization test
structures
Module 8. THE FUTURE (nanotechnology)
 Limits of CMOS - scaling issues and obstacles to further scaling
 theoretical limits (thermal limit, quantum limit)
 technological limits (dielectric scaling, high leakage current, breakdown
voltage in junctions, increased interconnections delays, lithography, power
dissipation)
 economical limits
Bio-electric computers
Quantum computers
Molecular electronics
‘Smart’ lab-on-a-chip
Plastic/Printed IC’s
‘Self-assembly’
Vertical/3D CMOS
Micro-wireless nets
Integrated Optics
Metal gates
Hi-k/metal oxides
Low-k w/Cu
SOI
+2
106-107-x lower power
for ‘lifetime’ micro-batteries
Wearable communicators,
Wireless remote medicine,
‘Hardware over the Internet’
Pervasive voice recognition,
‘Smart’ transportation, etc.
Full motion mobile video,
Fully integrated mobile office
Now
True neural computing for
‘Intelligent’ communicators,
controllers, assistants
+4
+6
(source: R. Cavin, SRC; Digital DNA Motorola)
+8
+ 10
+ 12
+ 14
+ 16 years
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Quantum and single-electron devices – quantum effects in nanoelectronics, quantum
dot resonant tunnelling transistor
 applications: quantum dot SETs fabrication, nanocrystal SETs, SET
memory devices
Molecular electronics – electronic devices from individual molecules; advantages and
disadvantages
 molecules designed with specific atoms, geometries, properties
 applications: molecular switch, molecular diode, self-assembled molecular
electronics starting from SAMs
 challenges: transistor fabrication, integration on a chip, heat limit
Bottom-up approach
 self-assembly – definition; examples: thiols (RSH) on Au surface, Si
terminated chains on glass, multilayered self-assembly; applications: SAMbased lithography and anti-stiction coatings in MEMS
 ionic self-assembly (charged particles) – controlled successive stacking on
patterned surfaces, applications in nonlinear optics, LED, photovoltaics
polymers for solar cells
 DNA self assembly – material properties, role: DNA used as glue to
assemble arrays of molecules and nanoparticles, practical examples,
synthesis and preparation of complementary DNA; selective attachment of
DNA strands to substrate and devices
Fullerene and nanotubes – definition , structure, helicity, topology, types: single-wall
and multi-wall
 synthesis: electric arc discharge, laser evaporation, catalytic CVD
 orientation, cutting with STM, electronic properties (semiconductor, metal),
mechanical properties
 potential applications and advantages: quantum wire interconnects, diodes
and transistors, data storage, field emitters flat panel displays, THz
oscillators, nanoprobes for AFM, sensors, nanogears
 technological challenges: large scale integration, reliability and control,
controlled doping, process integration
Spintronics
Nanotechnology in magnetic systems – principle of magnetic recording, limitations,
nanostructured magnetic media: self-assembled colloid magnetic particles, quantum
storage, magnetoresistive heads, giant magnetoresistance
Nanotechnology in integrative systems (NEMS): from MEMS to NEMS,
nanomachining of single crystal layers, nuclear magnetic resonance on
nanoparticles, nanoelectrometer, nanoscopic transduction, molecular NEMS
Nanotechnology in optoelectronics – quantum effects in optoelectronics, epitaxial
quantum dots, self-organized dots, colloid nanocrystal synthesis, quantum dot lasers,
photonic bandgap materials, self-assembled photonic structures
Bionanotechnology –detection and manipulation of molecules, nanofluidics, lab on a
chip, monolithic nanomachining, nano-syringe
 biomimetism –learning by imitating nature, biomimetic films, biosensors
 retinal circuitry morphed into silicon, astroglial cell growth on Si structures,
cell growth on patterned surfaces
 biohybrid devices have also a human inspired component (device),
molecular motors, nanopropeller
September 2003