ISE 316: Manufacturing
Engineering I: Processes
Micro/Nano-Scale Manufacturing
Outline
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Historical Perspective and Introduction
Why make things very small
Sensors and Actuators
Micro/nano-scale manufacturing
processes
If at first, the idea is not absurd,
then there is no hope for it.
- Albert Einstein
MEMS & Nanotechnology: A Glimpse
1822: Nicéphore Niépce invents lithography to pattern a
portrait. Five years later, Lemaître etched out the engraving
with a strong acid
1939: First p-n junction on a semiconductor (W. Schottky)
Cardinal d’Amboise
1948: First transistor (J. Bardeen, W.H. Brattain, W.
Shockley) http://www.pbs.org/transistor/science/events/pointctrans.html
1958: First integrated circuit developed at Texas
Instruments. Jack Kilby wins the Nobel at 2000
First IC
1959: Richard Feynman dreams big (Oops, small!)
Why can’t we write the entire 24 volumes of
Encyclopedia Brittanica on the head of a pin?
MEMS & Nanotechnology: A Glimpse
1965: First MEMS device? Resonant
gate transistor built by Nathanson,
Newell and Wickstrom
1965: Gordon Moore foretells the future of silicon industry
Every 2 years: #
transistors double; cost
remains same or
decreases. On the
same scale in the auto
industry, cars would
cost 5 cents and
average 300000 mpg
today
A View from Macro to Micro to Nano
•Human hair: 50,000 nm across
•Viruses range in size from 20 to 300
nanometers (nm)
•10 hydrogen atoms in a line, 10 Angstroms
(or 1 nm)
Nanoparticles exist all around us – in sea,
air, cigarette smoke, and diesel exhaust.
So, what is different today?
Why is the issue of nanotechnology
generating so much discussion?
MEMS & Nanotechnology: A Glimpse
1989: Breakthrough in MEMS. Polysilicon micromotors built by Tai and
Muller. Lateral comb drive actuator built by Tang, Nguyen and Howe
hair
Stator
combs
Rotor
1994: Digital micro-mirror device (DMD) from Texas Instruments
1995: Commercial accelerometer from
Analogue Devices
MEMS & Nanotechnology: A Glimpse
IC vs MEMS Technology
0.75 m
AMD K6 Microprocessor
(top 6 layers only)
TI - DMD
MEMS & Nanotechnology: A Glimpse
Is there a limit?
What are the issues?
Fabrication (180 nm)
Materials
Physical mechanisms
MEMS & Nanotechnology: A Glimpse
1985: R. Smalley, R. Curl and H. Kroto discovers Buckminsterfullerene or
Bucky ball. Nobel in 1996.
A C60 molecule
Nano-abacus of C60 molecules
http://jcrystal.com/steffenweber/POLYHEDRA/p_00.html
Nano materials
• Carbon nanotubes (CNTs; also known as buckytubes)
are allotropes of carbon with a cylindrical nanostructure.
Nanotubes have been constructed with length-todiameter ratio of up to 132,000,000:1,[1] significantly
larger than any other material. These cylindrical carbon
molecules have novel properties, making them
potentially useful in many applications in
nanotechnology, electronics, optics, and other fields of
materials science, as well as potential uses in
architectural fields.
Armchair and zigzagcarbon
nanotube
Multiwall nanotubes
MEMS & Nanotechnology: A Glimpse
1986: (1) Atomic Force Microscope is invented.
NaCl on Mica
(2) Eric Drexler publishes “Engines of Creation”
www.foresight.org/EOC/Engines.pdf
During the early decades of the 21st century, the advent of practical molecular
manufacturing technology will make it possible to fabricate inexpensively
almost any conceivable structure allowed by the laws of physics.
Consequences will include immensely powerful computers, abundant and very
high quality consumer goods, and microscopic devices able to cure most
diseases by repairing the body from the molecular level up.
MEMS & Nanotechnology: A Glimpse
1991: Sumio Ijima discovers
carbon nanotubes
http://www.photon.t.u-tokyo.ac.jp/~maruyama/wrapping.files/frame.html
1997: DNA based micromechanical device built
MEMS & Nanotechnology: A Glimpse
2001: Carbon nanotube based logic demonstrated
Nano bearings
Nano gears
Should we borrow from Nature?
NATURE
vs.
ENGINEERING
Billions of years to evolve
Revolutionary, Ingenuity driven
Does not use metals
driven
Metals and Artificial materials
(e.g. Stone Age  Iron Age)
Movement by sliding/contraction
The Wheel
Energy storage
Gravitational/ Elastic
Electrical and Kinetic
A wet technology
Mostly dry
Smooth shapes
Sharp corners, rectangular
Nanometer: A Different Perspective
• Human hair: 50,000 nm across
• Bacterial cell: a few hundred nanometers
• Seeable with unaided human eye: 10,000
nanometers
• 10 hydrogen atoms in a line
Reasons to Miniaturize
Miniaturization
Attributes
Reasons
Low energy and little Limited resources
material consumed
Arrays of sensors
Redundancy, wider dynamic range, increased
selectivity through pattern recognition
Small
Small is lower in cost, minimally invasive
Favorable scaling
laws
Forces that scale with a low power become more
prominent in the micro domain; if these are
positive attributes then miniaturization favorable
(e.g. surface tension becomes more important than
gravity in a narrower capillary)
Reasons to Miniaturize
Miniaturization
Attributes
Reasons
Batch and beyond
batch techniques
Lowers cost
Disposable
Helps to avoid contamination
Breakdown of macro New physics and chemistry might be developed
laws in physics and
chemistry
Smaller building
blocks
The smaller the building blocks, the more
sophisticated the system that can be built
Need for Scaling
• As linear size
decreases behavior
changes.
– Not well understood on
the nano-scale.
– Scaling represents an
approximation to assist
in understanding.
• Scaling helps to explain
nature and can also be
used to design devices.
Scaling
• If a system is reduced isomorphically in
size (i.e. scaled down with all dimensions
of the system decreased uniformly), the
changes in length, area and volume ratios
alter the relative influence of various
physical effects.
• Sometimes these effect the operation in
unexpected ways.
Is scaling different in the micro
world?
Scaling of Length, Surface Area
and Volume
• What happens
as an object
shrinks?
– Area  L2
– Volume  L3
L
L
L
Why Whales Swim Faster
L3
L2
1
FD  C D Au 2  L2
2
where
CD: drag coefficient
ρ: density of fluid
A: largest projected area of the body
u: velocity
Scaling of Mechanical Systems
W
Scaling of Mechanical Systems
force L2
acceleration 
 3  L1
m ass L
In nano-mechanical systems
accelerations are large.
characteristic _ time_ scale  frequency1  L
speed  (acceleration)(time)  ( L1 )(L)  L0
Speed is length scale invariant.
Actuators
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Electrical
Electrostatic
Magnetic
Thermal
Electrostatic Motors
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Polysilicon micromotor:
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Rotor sits atop a 0.5mm layer of polysilicon that acts as an
electrostatic shield.
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Rotor, hub, stators formed from 1.5mm polysilicon.
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A 2.0mm polysilicon disk is attached to rotor.
Projection TV Technology
Use of electrostatic
torque for mirror
positioning.
Mirror mechanism
for DLP TV
(Texas Instruments)
Thermal Actuation
The current flow produces Joule
heating that in turn imparts a large
thermal stress on the device,
concentrated in the long thin beam.
The thermal expansion of the thin
beam causes the device to bend at
the short thin beam. The blade
rotates in the plane of the
substrate.
Piezoelectric Actuators
Recall the piezoelectric effect:
Ideal Sensor
• Zero Mass: no additional
mass, no thermal
compensation (no latent
heat energy stored),
thermally equilibrate
infinitely rapid, infinitely
wide dynamic response.
• Zero physical size: Could
be installed virtually
anywhere, extreme spatial
resolution by arrays.
• Zero energy.
Historically, most
successful applications
of MEMS techniques fall
in the “Sensors”
category.
MEMS Sensors are
close. They offer high
sensitivity, can be batch
fabricated (low cost, high
volume), some times
wireless and are robust
Mechanical Sensing
• Micro-mechanical structures at heart of
design process
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Beams that act as springs
Experience force and/or displacement
Deform under force, pressure, flow, etc.
Measure deflection
• Deflection equations developed for macroscale and assume:
• Material properties do not change
• No residual stresses
Silicon is generally
used for micromechanical
structures.
Concept
F  kx
Sensor and Transducer
• Sensor: Converts force to displacement
x  F /k
• Sensitivity: 1/k
• Transducer : Apply force to get displacement
• k can be constant or varying with force
Cantilever Beam
k  3EI / L
3
The left cantilever bends as the protein PSA binds to the
antibody. The other cantilevers are exposed to different
proteins found in human blood serum.
Another View of Sensing
Displacement as a means of sensing!
Mechanical Sensing
• Micro-mechanical structures at heart of
design process
•
•
•
•
Beams that act as springs
Experience force and/or displacement
Deform under force, pressure, flow, etc.
Measure deflection
• Deflection equations developed for macroscale and assume:
• Material properties do not change
• No residual stresses
Silicon is generally
used for micromechanical
structures.
Concept
F  kx
Sensor and Transducer
• Sensor: Converts force to displacement
x  F /k
• Sensitivity: 1/k
• Transducer : Apply force to get displacement
• k can be constant or varying with force
Cantilever Beam
k  3EI / L
3
The left cantilever bends as the protein PSA binds to the
antibody. The other cantilevers are exposed to different
proteins found in human blood serum.
Sensors: Mechanical
Measurement
Atomic Force Microscope
Accelerometers
When the reference frame is accelerated, the
acceleration is transferred to the proof mass
through the spring. The stretching of the spring,
which is measured by a position sensor
(represented as a length scale in the figure), gives
the acceleration when the proof mass is known.
Natural frequency
Applications:
Inertial guidance
system, airbags,
vibration measurement
Damping coefficient
Accelerometers
Piezoelectric Sensing
Chemical
Sensor
Biological Sensing
Diagram of interactions
between target and probe
molecules on cantilever beam.
Specific biomolecular
interactions between target and
probe molecules alter the
intermolecular nanomechanical
interactions
within a self-assembled
monolayer on one side of a
cantilever beam. This can
produce a sufficiently large
force to bend the cantilever
beam and generate motion.