ee c245 – me c218 introduction to mems design fall 2008
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EE C245 – ME C218Introduction to MEMS Design
Fall 2008Fall 2008
Prof Clark T C NguyenProf. Clark T.-C. Nguyen
Dept of Electrical Engineering & Computer SciencesDept. of Electrical Engineering & Computer SciencesUniversity of California at Berkeley
Berkeley, CA 94720y
L t 1 D fi iti d I ti f MEMS
EE C245: Introduction to MEMS Design Lecture 1 C. Nguyen 8/28/08 1
Lecture 1: Definition and Incentives for MEMS
Instructor: Prof. Clark T.-C. Nguyen
• Education: Ph.D., University of California at Berkeley, 1994• 1995: joined the faculty of the Dept. of EECS at the U i it f Mi hiUniversity of Michigan
• 2006: (came back) joined the faculty of the Dept. of EECS at UC Berkeleyy
• Research: exactly the topic of this course, with a heavy emphasis on vibrating RF MEMS
• T hi ( t th U fM) i l t i t i it d i • Teaching: (at the UofM) mainly transistor circuit design courses, from undergraduate to graduate
• 2001: founded Discera, the first company to commercialize f , f mp y mmvibrating RF MEMS technology
•Mid-2002 to 2005: DARPA MEMS program managerran 10 different MEMS based programsran 10 different MEMS-based programstopics: power generation, chip-scale atomic clock, gas analyzers, nuclear power sources, navigation-grade gyros,
hip li mi i m t l t l
EE C245: Introduction to MEMS Design Lecture 1 C. Nguyen 8/28/08 2
on-chip cooling, micro environmental control
Course Overview
• Goals of the course:Accessible to a broad audience (minimal prerequisites)D i h iDesign emphasis
Exposure to the techniques useful in analytical design of structures, transducers, and process flowsof structures, transducers, and process flows
Perspective on MEMS research and commercialization circa 2008
• Related courses at UC Berkeley:EE 143: Microfabrication TechnologyCS 194 (EE 147): Introduction to MEMSCS 194 (EE 147): Introduction to MEMSME 119: Introduction to MEMS (mainly fabrication)BioEng 121: Introduction to Micro and Nano Bi t h l d Bi MEMSBiotechnology and BioMEMSME C219 – EE C246: MEMS Design
• Assumed background for EE C245: graduate standing in
EE C245: Introduction to MEMS Design Lecture 1 C. Nguyen 8/28/08 3
Assumed background for EE C245: graduate standing in engineering or physical/bio sciences
Course Overview
• The mechanics of the course are summarized in the course handouts, given out in lecture today
C I f i ShCourse Information SheetCourse descriptionCourse mechanicsCourse mechanicsTextbooksGrading policy
S ll bSyllabusLecture by lecture timeline w/ associated reading sectionsMidterm Exam: tentatively set for Thursday, Oct. 23Final Exam: Saturday, Dec. 20, 12:30-3:30 p.m.Change this Final Exam time?Change this Final Exam time?Project due date TBD (but near semester’s end)
EE C245: Introduction to MEMS Design Lecture 1 C. Nguyen 8/28/08 4
Lecture Outline
• Reading: Senturia, Chapter 1g p• Lecture Topics:
Definitions for MEMSMEMS roadmapMEMS roadmapBenefits of MiniaturizationExamplesp
GHz micromechanical resonatorsChip-scale atomic clockMicro gas chromatographMicro gas chromatograph
EE C245: Introduction to MEMS Design Lecture 1 C. Nguyen 8/28/08 5
MEMS: Micro Electro Mechanical System
d d h ( E ) h• A device constructed using micromachining (MEMS) tech.• A micro-scale or smaller device/system that operates mainly via a mechanical or electromechanical meansvia a mechanical or electromechanical means
• At least some of the signals flowing through a MEMS device are best described in terms of mechanical variables, e.g., , g ,displacement, velocity, acceleration, temperature, flow
Input: Output:
MEMSvoltage, currentacceleration, velocity
light, heat …
voltage, currentacceleration, velocity
light, heat, …
Control:voltage current
[Wu, UCLA]Transducer to Convert Controlto a Mechanical voltage, current
acceleration velocity
light heat
to a Mechanical Variable (e.g., displacement,
velocity, stress,
EE C245: Introduction to MEMS Design Lecture 1 C. Nguyen 8/28/08 6
Angle set by mechanical meansto control the path of light
light, heat, …y, ,heat, …)
Other Common Attributes of MEMS• Feature sizes measured in microns or less
Gimballed, SpinningMacro-Gyroscope
MicromechanicalVibrating Ring Gyroscope
80 mm[Najafi, Michigan]
Macro-Gyroscope Vibrating Ring Gyroscope
MEMSTechnologygy
1 mm
(for 80X sizeReduction)
•Merges computation with sensing and actuation to change the i d l h h i l ld
Signal Conditioning Circuits
way we perceive and control the physical world• Planar lithographic technology often used for fabrication
can use fab equipment identical to those needed for IC’s
EE C245: Introduction to MEMS Design Lecture 1 C. Nguyen 8/28/08 7
can use fab equipment identical to those needed for IC showever, some fabrication steps transcend those of conventional IC processing
Bulk Micromachining and Bonding
• Use the wafer itself as the
MicromechanicalVibrating Ring Gyroscope
• Use the wafer itself as the structural material
• Adv: very large aspect Adv very large aspect ratios, thick structures
• Example: deep etching and f wafer bonding 1 mm
[Najafi, Michigan] [Pisano, UC Berkeley][Pisano, UC Berkeley]
Silicon SubstrateSilicon SubstrateSilicon SubstrateSilicon Substrate
MovableStructure Electrode
Silicon Substrate
Gl S b t t
Silicon SubstrateSilicon Substrate
Gl S b t t
EE C245: Introduction to MEMS Design Lecture 1 C. Nguyen 8/28/08 8
Glass SubstrateGlass SubstrateMetal Interconnect
AnchorMicrorotor
(for a microengine)
Surface Micromachining
EE C245: Introduction to MEMS Design Lecture 1 C. Nguyen 8/28/08 9• Fabrication steps compatible with planar IC processing
Single-Chip Ckt/MEMS Integration• Completely monolithic, low phase noise, high-Q oscillator (effectively, an integrated crystal oscillator)
OscilloscopeOscilloscopeOutput
Waveform
• To allow the use of >600oC processing temperatures
[Nguyen, Howe 1993][Nguyen, Howe 1993]
EE C245: Introduction to MEMS Design Lecture 1 C. Nguyen 8/28/08 10
To allow the use of >600oC processing temperatures, tungsten (instead of aluminum) is used for metallization
3D Direct-Assembled Tunable L
EE C245: Introduction to MEMS Design Lecture 1 C. Nguyen 8/28/08 11
[Ming Wu, UCLA]
Technology Trend and Roadmap for MEMSs
108
109
DistributedStructural Digital Micromirror
Pentium 4
ompu
te
sist
ors
106
107Structural
ControlTerabit/cm2
Data Storage
DisplaysADXL-50
Digital MicromirrorDevice (DMD)CPU’s
Phased Array
bilit
y to
co
of T
rans
104
105
10
Adaptive
Integrated FluidicSystems
InertialNavigationOn a Chip
Displays
W
OMM 32x32
i-STAT 1Caliper
Phased-ArrayAntenna
crea
sing
ab
mbe
r o
2
103
104 AdaptiveOptics
Optical Switches& Aligners
Weapons,Safing, Arming,
and FusingADXL-278
Future MEMSIntegration Levels
Enabled Applications
Caliper
inc
Num
101
102
ADXL-78ADXRS
Number of Mechanical Components
100
100 101 102 103 104 105 106 107 108 109Majority of
Early MEMS
EE C245: Introduction to MEMS Design Lecture 1 C. Nguyen 8/28/08 12
increasing ability to sense and actNumber of Mechanical Componentsy
Devices(mostly sensors)
Benefits of Size Reduction: IC’s
•Numerous benefits attained by scaling of transistors:
Higher Current Drive FasterSpeed
Higher Current DriveLower Capacitance
Higher Integration DensityLower Supply Voltage
LowerPower Lower Supply VoltagePower
Hi h Ci it C l it & E f S lHigher Circuit Complexity & Economy of Scale
• But … some drawbacks:poorer reliability poorer reliability (e.g., hot e- effects)lower dynamic range ( l kt ff )
EE C245: Introduction to MEMS Design Lecture 1 C. Nguyen 8/28/08 13
(analog ckts suffer)
Example: Micromechanical Accelerometer
• The MEMS Advantage:>30X size reduction for accelerometer mechanical element m
Tiny mass means small output need
accelerometer mechanical elementallows integration with IC’s
Basic Operation Principle
400 μmintegrated transistor
circuits to compensate
xo
Basic Operation Principle
maFx i =∝
xSpring
Displacement
a Inertial Force
Spring
A l ti
Proof Mass
EE C245: Introduction to MEMS Design Lecture 1 C. Nguyen 8/28/08 14
AccelerationAnalog Devices ADXL 78
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