Transcript Document 7305443

UCI
UCI MicroSystems Laboratory
MicroSensors and MicroActuators
Andrei M. Shkel
MicroSystems Laboratory
Mechanical and Aerospace Engineering Department
University of California, Irvine
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Plan for Today
Microsensors and MicroActuators
 Words of Wisdom from Graduate Students


Max Perez
 Alex Trusov
 Nivedan Tiwary

MicroSystems Lab Tour – EG 2110
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Pioneers of the 1st Silicon Revolution
Physicists John Bardeen, William B. Shockley, and Walter Brattain
shared the 1956 Nobel Prize for jointly inventing the transistor, a
solid-state device that could amplify electrical current.
1947
Vacuum tube
A model of the first transistor
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Jack Kilby’s Big Idea:
“All parts of a circuit should be made of the same material-silicon”
(Nobel Prize in Physics, 2000)
Frequency shifter: a transistor and other
components on a slice of germanium (7/16-by1/16-inches in size ). Invented by Jack Kilby, 1958.
In 1961Fairchild Camera and
Instrument Corp. invented
Resistor-Transistor Logic.
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Smaller, Cheaper, Faster, …
The Pentium 4 chip contains 42 million transistors !!!
As transistors become smaller, they
become faster, you can pack more
and more of them on a chip, and
chips are able to store and process
more information. To date, this has
been the silicon revolution.
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Computers
1940-1950
In 1947, transistor is
invented
• Vacuum tubes & mechanical
relays: UNIVAC, ENIAC
• 30 tons
• 150KWatt
• 80 bytes of memory
In 1958 Jack Kilby
introduced concept of
“Integrated Circuits”
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Moore’s Law
• Moore's Law. Estimates that the
number of transistors/chip doubles
every 18 months.
• Exponential Growth!
• Has been true for 20 years!
If we had similar progress in automotive technology, today you could buy a Lexus
for about $2. It would travel at the speed of sound, and get about 600 Miles on a
thimble of gas. -Randall Tobias: Former Vice Chairman of AT&T.
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What is next ?
To give chips the ability to sense, communicate, learn, and interact
Sense
Communicate
Learn
Interact
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The Next Logical Step …
…connect chips to the physical world
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From Pure Electronics Into …
MicroMechanics
Chemistry
Medicine
Genetics
Biology
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Micromachining
Surface Micromachining
Deposition
Photolithography
Etching
Reactive Ion Etching (RIE)
Wafer Bonding
Wet etch (anisotropic or isotropic)
Micrograph showing the
surface micromachined structure
SEM micrograph showing the
high aspect ratio feature
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Micro-Fabrication
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Batch fabrication
What is batch fabrication?
Example: Cronos surface micromachining
Courtesy of IMI (http://www.imi-mems.com)
Courtesy of the Cronos website (http://www.memsrus.com)
• Through batch fabrication, device and
electronics can be made on the same chip in the
same fabrication sequernce!
• Thousands of devices can be made at one
time, reducing costs
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MEMS GO Beyond …
Thicker films
deeper etches
fewer steps
Multiple Processing Cycles
DEPOSITION
OF
MATERIAL
PROBE
TESTING
SECTIONING
Special probing, sectioning and
handling procedures to protect
released parts
PATTERN
TRANSFER
Removal of underlying
materials to release
mechanical structures
REMOVAL
OF
MATERIAL
INDIVIDUAL
ASSEMBLY
PACKAGE
DIE
INTO PACKAGE
SEAL
Encapsulate some parts
of device but expose others
FINAL
TEST
Test more than just
electrical functions
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New Design Paradigm
• Compliance - a preferred effect
Conventional rigid-link crimping mechanism with
six moving parts, six pin joints, and a spring*
• Elastic deformation - an intended source for motion
and forces
• Devices can be constructed out of a single-piece
• Design compliant mechanisms is based combining the
traditional kinematic formulations with continuum
mechanics based structural optimization methods
Compliant crimping mechanism*
Compliant Clamp*
Compliant gripper*
Silicon Microtweezer. Photo courtesy of Chris Keller,
MEMS Precision Instruments
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What is a Micro-Sensor ?
Micro Sensors measure the environment without modifying it. Micro sensors are useful
because their small physical size allows them to be less invasive and work in smaller
areas.
Examples of micro sensors include devices which measure pressure, acceleration,
strain, temperature, vibration, rotation, proximity, acoustic emission, and many
others.
Transduction mechanisms are used by micro sensors to convert environmental changes
into electrical signals. Many of these transduction methods use mechanical structures.
planar polysilicon
pressure transducer
Polysilicon resonant
transducer
Microdynamomemter
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What is a Micro-Actuator ?
Micro Actuators interact with the environment. Micro actuators are useful because
the amount of work they perform on the environment is small and therefore can be very precise
Examples: relays, optical fiber switches, and other micro positioners.
They can also be used as the active component of a sensor
Energy for actuator motion is stored in volumes. The larger the volume the
larger the energy storage; and therefore, the greater energy available for actuator motion.
Surface area sets the fabrication costs of most micro actuators. This is
because most micro actuators are created with modified integrated circuit fabrication techniques where the
device area sets the cost. In a sense the height of the structure is free as long as there is additional time
associated with the creation of tall devices which take up the same area.
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Optical MEMS
Laser-to-fiber coupling
Micropositioners of mirrors
and gratings
High-resolution raster scanner
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Micromachining is not precision machining!
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Fabrication Imperfections
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Benefits of Micromachining






Small size
Significantly decrease in cost
Low power consumption
Integrated MEMS solutions
(mechanics + IC)
Faster dynamic response
In some cases increased reliability
Photo courtesy of
Draper Lab.
Silicon motor with a strand
of human hair.
Photo courtesy of BSAC
Z-axis accelerometer


Surface Micromachining
 3 mass sensor
 2 µm polysilicon
 2 µm minimum gap
Electronics
 standard 2 µm CMOS
 ~1000 transistors
On one wafer can
be fabricated
more than 10,000
integrated systems
Ref: Lemkin, M., et. al., A 3-axis surface micromachined
accelerometer, ISSCC, Tech. Digest, pp. 202-203, 1997
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From Micro-structures to Micro-systems
Co-Fabricating Electronics and
Microstructures: not easy!
• Mixed MEMS + CMOS – “boutique process” …
expensive!
• MEMS first, CMOS last – own your foundary or control
your own CMOS fab (example: Sandia and Analog
Devices)
• CMOS first, MEMS last – best way, but thermal budget
for MEMS is a challenge
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iMEMS Manufacturing Process
1. Surface micromachining process using polysilicon
2. Well filled with oxide and planarized (CMP)
3. Standard CMOS process
Ref: Smith, J.H., et. al., Embedded micromechanical devices for the monolithic
integration of MEMS with CMOS, IEDM, Tech. Digest, pp. 609-612, 1995.
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Angle Gyroscopes Implemented in Sandia’s
Integrated MEMS (iMEMS) Technology*
Z-axis RIG
X-axis RIG
Die includes one X-axis RIG*
Z-axis RIG
Die includes two Z-axis RIGs*
*These dies also include basic drive/sense electronics and rate gyroscopes designed by Ashwin Seshia
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Projects on Sensor Development

SiC Pressure Sensors
ALIGNMENT
STAGE
SPECTRUM
ANALYZER
(sponsored by Endevco Inc.)
-65-600 F, 0.1% Full Scale PSIA

High-g accelerometers
TUNABLE
LASER
(sponsored by VIP Sensors)
DC to 20kHz, upto 5,000g

Optical accelerometers
(sponsored by NSF, VIP, Agoura)
micro-g, EM immune, 1kHz band

Gyroscopes
(sponsored by NSF, BEI,Honeywell)
-40-125C, better than 1 deg/sec
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Measurement of Rotation

Navigation in Nature

Engineered Devices

Inclinometers, Gyroscopes,…
Rotating Mass
Ring Laser
Fiber Optic
Vibrating Mass
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Gyroscopes …
6-DOF Inertial Sensor System
10 mm
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Vibratory MEMS Gyros
Sense
direction
(y)
Anchor
Sense
Capacitors
Single proof mass driven into
resonance in x direction.
Coriolis Force in y direction.
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The Senses
Vision
Smell
Hearing
Taste
Touch
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Artificial Implants
Bionic retina
Artificial heart
Cochlear implant
Artificial vessels
Artificial lung
Artificial limb
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Totally Implantable Vestibular Prosthesis
MEMS Vestibular Prosthesis
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5mm
Natural
Balance
MEMS
Gyroscope
Full range
200deg/sec
200deg/sec
Sensitivity
0.5deg/sec
0.1deg/sec
Bandwidth
<8Hz
<500Hz
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MEMS Vibratory Gyroscopes
5 Surface-Micr. Runs + 6 Bulk-Micr. Runs.
9 patents (3 issued), 4 commercialized,
2 PhDs, 4 dozens of publications
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Recent Rate-Table Measurements
SOI Decoupled Gyro -200 +200 deg/sec
3
0.4
2
0.2
1
0
-30
-20
-10
0
10
20
30
Vout [V]
Vout [V]
SOI Decoupled Gyro -30 +30 deg/sec
0.6
0
-200
-100
0
-0.2
-1
-0.4
-2
-0.6
Input rate [deg/sec]
100
200
-3
Input rate [deg/sec]
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I/O Mathematical Model

H s 
Change in
resting potential
due to rotational
accelerations
 As
1 Ls
1   A s 1   1s 1   2 s 
where  A is related to the level of adaptation,
 L is related to hair cell response due to velocity of cupula,
 1 is a ratio of damping over the spring constant of cupula,
and  2 is a ratio of momentum of cupula to damping.
Goldberg, J. and C. Fernandez (1971). “Physiology of peripheral neurons innervating semi-circular
canals of the squirrel monkey. II. Response to sinusoidal stimulation and dynamics of peripheral
vestibular system.” Journal of Neurophysiology 34: 661.
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Experimental Results
Experimental prototype
Frequency Domain
F3=50*V2
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Opportunities
• There is a need …
• Driving hope:
• medium performance devices
• small size
• consume little power
• outperform natural organ
• Challenges:
• Interface with neurons
• long-term stability of the sensor
• drift suppression over time
• accurate mathematical model
• Bio-compatible package
• wireless programming
• …
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Development Cycle
Testing
IDEA
Concept
Packaging
Fabrication
Modeling-Simulation
Design-Layout
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Gallery of Lab’s Micro-Devices
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Lab’s Applications
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Silicon Anteaters
20 m
Current Post-Docs and Students
• Dragos Constantin (Post-Doc)
• Max Perez (MAE, M.S./Ph.D.)
• Adam Schofield (MAE, M.S./Ph.D)
• Alex Trusov (MAE, M.S./Ph.D.)
• Andreu Fargas (UPC, Ph.D.)
• Jasmina Casals (UPC, Ph.D.)
• Jesper Eklund (EECS, Ph.D.)
• Chandra Tupelly (MAE, M.S./Ph.D)
• Nivedan Tiwary (MAE, Ph.D.)
• Alex Nikolaenko (MAE, Ph.D.)
• Ilya Chepurko (Researcher)
Alumni
Chris Painter (Ph.D. 2005), Cenk Acar (Ph.D. 2004), Sauman Holston (M.S., 2004), Sebnem Eler
(Compac Inc.) M.S. 2001; Jung-sik Moon (Solus Inc.) M.S. 2001; Andreu Fargas (Consulting) M.S.
2001; Johanna Young (UCI GRA) M.S. 2001; Rabih Zaouk (MAE M.S./Ph.D.); Alia Marafie (MAE,
M.S.); John Gemmell (Materials, Ph.D.); Chris Ikei (BioMed, Ph.D.); Liz Hollenbeck
(MAE,M.S./Ph.D.); Carol Chou (ECE, B.S.); Matt Murakami (ECE, M.S.); Joann Dacanay (MAE,
B.S. ); Michael Williams (ECE, B.S.); Jasmina Casals (MAE, M.S.); Michael Williams (ECE, B.S.);
Le Yan (MAE, M.S.); Jiayin Liu (MAE, M.S.)
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A View of the Future
Sandia Lab’s Vision:
“We believe that the next step in the silicon revolution will be
different, and more important than simply packing more transistors
onto the silicon. We believe that the hallmark of the next thirty
years of the silicon revolution will be the incorporation of new
types of functionality onto the chip; structures that will enable the
chip to not only think, but to sense, act and communicate as well.
This revolution will be enabled by MEMS”
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