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I SSCC 2 0 1 2 Tutorial Getting I n Touch w ith MEMS: The Electrom echanical I nterface Dr. Aaron Partridge ap@sitime.com SiTime, Corp. February 19, 2012 Overview These slides accompany the 2012 ISSCC Tutorial, Getting In Touch with MEMS:

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I SSCC 2 0 1 2 Tutorial Getting I n Touch w ith MEMS: The Electrom echanical I nterface

  • Dr. Aaron Partridge

ap@sitime.com SiTime, Corp. February 19, 2012

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Aaron Partridge 2 of 70 Getting In Touch with MEMS: The Electromechanical I nterface

Overview

These slides accompany the 2012 ISSCC Tutorial, Getting In Touch with MEMS: The Electromechanical Interface. The tutorial is written for practicing IC engineers and

  • students. No MEMS background is needed.

The goal is to expand the attendee’s potential role from circuit designer to system designer. From “Here is the MEMS device, design the interface circuit.” into “Here is the problem, define an optimal solution.”

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Aaron Partridge 3 of 70 Getting In Touch with MEMS: The Electromechanical I nterface

Outline

  • MEMS Materials, Processes, and Example Applications
  • Electrical Interfaces
  • Scaling Laws
  • Packaging is Critical
  • CMOS Integration
  • How to Succeed
  • References
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Aaron Partridge 4 of 70 Getting In Touch with MEMS: The Electromechanical I nterface

  • MEMS Materials, Processes, and Example Applications
  • Electrical Interfaces
  • Scaling Laws
  • Packaging is Critical
  • CMOS Integration
  • How to Succeed
  • References
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Aaron Partridge 5 of 70 Getting In Touch with MEMS: The Electromechanical I nterface

Materials

  • Standard Semiconductor Materials

n Silicon (single crystal and poly). n Oxide (thermal and deposited). n Nitride. n Alum inum .

  • Unusual Materials

n Gold, various other metals. n Piezoelectrics (AlN mostly). n Plastics (e.g. SU-8). n And then just about anything else.

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Aaron Partridge 6 of 70 Getting In Touch with MEMS: The Electromechanical I nterface

Processes

  • Early in MEMS many unusual

etches were comm on.

  • Now standard fab process

are preferred when possible.

  • A few special processes

n Bosch etch. n HF vapor etch. n Oxide plasma release. n Xenon difluoride (XeF2) release.

  • Deep etches are com mon.

Tuning fork resonator, Bosch 2003

  • S. Pourkam ali, F. Ayazi, 2004
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Aaron Partridge 7 of 70 Getting In Touch with MEMS: The Electromechanical I nterface

Example Applications

  • MEMS will find its way into practically every application.
  • Right now, it is strong in

n Automotive (pressure, acceleration, rotation). n Consumer (acceleration, rotation, time). n Industrial and Military (pressure, acceleration). n Medicinal (pressure, biological sensors).

  • Future hot apps will be

n Medical, for diagnostic tools. n Timing, to replace quartz. n RF Filters, switches, etc. n Inertial, to sense motion of all types.

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Aaron Partridge 8 of 70 Getting In Touch with MEMS: The Electromechanical I nterface

Pressure Sensors

Sensimed intraocular pressure sensor in contact lens

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Aaron Partridge 9 of 70 Getting In Touch with MEMS: The Electromechanical I nterface

Accelerometers & Gyroscopes

Freescale accelerometer

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Microphones

Akustica microphone

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Light Modulators & Projectors

Two pixels in a TI DLP mirror array

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Aaron Partridge 12 of 70 Getting In Touch with MEMS: The Electromechanical I nterface

Resonators & Oscillators

SiTime oscillator

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RF Switches

  • G. Rebeiz UCSD, RF switch
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  • MEMS Materials, Processes, and Example Applications
  • Electrical Interfaces
  • Scaling Laws
  • Packaging is Critical
  • CMOS Integration
  • How to Succeed
  • References
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Aaron Partridge 15 of 70 Getting In Touch with MEMS: The Electromechanical I nterface

Capacitive Overview

  • Capacitive transduction is used in 90% of MEMS

interfaces.

  • Good Points:

n Easy to build, no need for special materials. n With the Bosch etch we can make beautiful cap structures. n Can move small to large distances. n Can move in-plane and out-of-plane. n Can sense tiny displacements.

  • Bad points:

n Often will not deliver as much force as desired. n Needs bias voltage, sometimes large. n Output signals can be very small.

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Aaron Partridge 16 of 70 Getting In Touch with MEMS: The Electromechanical I nterface

Capacitive Drive

  • How does capacitive drive work?

Take a parallel plate example:

  • Were F= force, 0= permittivity,

w= width, h= height, g= capacitive gap, V= voltage.

  • The voltage squared gives

attractive forces and drive nonlinearity.

  • The gap squared gives

displacement nonlinearity.

2 2

2 V g wh F

c

ε =

V g h w F

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Aaron Partridge 17 of 70 Getting In Touch with MEMS: The Electromechanical I nterface

Capacitive Drive

  • Want bipolar force?
  • We can offset the attraction (pull

more and pull less) with DC bias and AC drive.

  • Set Vbias > > Vdrive and we get a

bipolar offset drive.

  • As bias is increased and drive is

decreased the linearity improves.

2 2

) ( 2

drive bias c

V V g wh F + = ε

drive bias c

  • ffset

V V g wh F

2

ε ≈

g h w Vbias+ Vdrive F

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Aaron Partridge 18 of 70 Getting In Touch with MEMS: The Electromechanical I nterface

Capacitive Drive

  • Second option for bipolar is

differential (pull one way, pull the other),

  • Offset and differential can be

combined,

  • Typical bias and drive are 5V

and 0.5V.

( )

2 2 2

2

right left c dif

V V g wh F − = ε

( )

left right bias c dif

V V V g wh F − ≈

2

ε

g h w Fdif Vleft g Vright

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Aaron Partridge 19 of 70 Getting In Touch with MEMS: The Electromechanical I nterface

Capacitive Drive

  • Interdigitated fingers

(combs) can move further and are m ore linear.

  • N is the number of fingers.
  • Since p does not effect Fc

it is linear in displacement.

  • Pairs of fingers can be

used differentially to linearize V and push-pull.

2

V g h N F

c dif

ε =

V g h p Fc V

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Aaron Partridge 20 of 70 Getting In Touch with MEMS: The Electromechanical I nterface

Capacitive Sense

  • For capacitive sensing, we

need to think about charge,

  • We all learned that,
  • But for MEMS sensing we

sometimes care more about,

  • And we use a bias Vdc, often

about 5V but can be 100’s!

dt dQ i CV Q / , = = ) / ( dt dV C i = ) / ( dt dC V i

dc

=

i

cap C

Any structures with dC/ dx

  • work. Fingers are common.
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Aaron Partridge 21 of 70 Getting In Touch with MEMS: The Electromechanical I nterface

Capacitive Sense

  • What you will need to do as an engineer

n Because capacitances are small, sense currents are small. n Design the lowest noise sense amps possible. n If noise is not critical then shrink the MEMS. n Always push the circuits, always simplify the MEMS.

  • Drive Circuits

n For AC system (gyros, vibrometers, oscillators) we need to sense AC current. n For DC systems (accelerometers) we need to modulate a carrier. n Clasic accelerometer drives a differential signal on plates and measures current with a lock-in amplifier.

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Aaron Partridge 22 of 70 Getting In Touch with MEMS: The Electromechanical I nterface

Capacitive Sense

  • Differential lock-in sense amp for accelerometers.

OUT

A

phase trim diff

  • sc

sensor

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Aaron Partridge 23 of 70 Getting In Touch with MEMS: The Electromechanical I nterface

  • M. Dugger, Sandia Labs
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Aaron Partridge 24 of 70 Getting In Touch with MEMS: The Electromechanical I nterface

Piezoresistive Overview

  • Transduces strain to resistance.
  • One of the earliest MEMS interfaces and still important.
  • Good points:

n There is mechanical gain, typically about 30x. n The common sensor structure is a Wheatstone bridge. n Silicon-friendly fabrication, doped resistors work well.

  • Bad points:

n Main problem is temperature sensitivity – moderately doped silicon resistors change about 0.5% per C or more. n 1/ f noise and drift can be problematic. n Only senses, does not drive.

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Aaron Partridge 25 of 70 Getting In Touch with MEMS: The Electromechanical I nterface

Piezoresistive Sense

  • A simple idea with may coefficients

– strain changes resistivity.

  • = change in resistivity, are

piezo coefficients, are stress. The form a sparse 6x6 matrix.

  • For specific cases the equation can

be simplified to,

∑

=

= ∆

6 1 λ λ ωλ ω

σ π ρ ρ

  • R

axial effective

R R σ π = ∆

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Aaron Partridge 26 of 70 Getting In Touch with MEMS: The Electromechanical I nterface

Piezoresistive Sense

  • Typical sense circuits are bridges.

n This minimizes the tem perature sensitivity that can swamp signals. n Input offset often vital – use switched caps, diversity, etc. n Often must minimize 1/ f noise – use switched topologies. n Temperature compensation of offset and gain variation is

  • ften needed.
  • See: A.A. Barlian, W-T. Park, J.R. Mallon Jr., A.J.

Rastegar, and B.L. Pruitt, “Review: Semiconductor Piezoresistance for Microsystems”, Proceedings of the IEEE, v.97, n.3, March 2009.

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Piezoresistive Sense

  • Bridge amp with temperature offset and gain correction

OUT A OUT Vbias

  • ffset

trim gain trim temp sense sensor

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Aaron Partridge 28 of 70 Getting In Touch with MEMS: The Electromechanical I nterface

  • A. Partridge, Stanford
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Aaron Partridge 29 of 70 Getting In Touch with MEMS: The Electromechanical I nterface

Piezoelectric Overview

  • Transduces force to voltage.
  • Aluminum Nitride (AlN) is the most common material.
  • Good points:

n Moderately easy to fabricate, available in MEMS foundries. n Can provide low impedance and tremendous power handing for RF. n Works well at high frequencies.

  • Bad points:

n Displacements are tiny, so not generally used for motion. n Rather low Q’s when used in resonators. n Does not transduce DC signals.

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Aaron Partridge 30 of 70 Getting In Touch with MEMS: The Electromechanical I nterface

Piezoelectric Drive and Sense

  • For sense and drive, think in

terms of S21 and S12.

  • In the simplest form,
  • Where t= thickness,

e= dielectric perm ittivity, and d-bar is the piezoelectric charge coefficient (a function

  • f material and orientation).

F ewh t d V =

V h w F t

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Aaron Partridge 31 of 70 Getting In Touch with MEMS: The Electromechanical I nterface

  • G. Vigevani, UC Berkeley
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Aaron Partridge 32 of 70 Getting In Touch with MEMS: The Electromechanical I nterface

Other Transducers

  • Therm al sensors, particularly thermistors, are often used

for IR im aging bolometers.

  • Chemical sensors of all kinds are used in biology.
  • There are lots of optical transducers, and this is an

important area for displays. Optical forces can even be used to drive MEMS, but that is rare.

  • Magnetic transducers are common in m acrosystems but

don’t work well in micro. They are rare.

  • There are endless other ways to transduce signals.
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Aaron Partridge 33 of 70 Getting In Touch with MEMS: The Electromechanical I nterface

Remem ber This:

You will usually need to design the lowest noise circuits possible. If the MEMS is producing extra signal then it should be simplified.

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Aaron Partridge 34 of 70 Getting In Touch with MEMS: The Electromechanical I nterface

  • MEMS Materials, Processes, and Example Applications
  • Electrical Interfaces
  • Scaling Laws
  • Packaging is Critical
  • CMOS Integration
  • How to Succeed
  • References
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Aaron Partridge 35 of 70 Getting In Touch with MEMS: The Electromechanical I nterface

Scaling Laws

  • Most things scale against us, not for us.
  • Mechanical structures

n Volume and mass: x3 (simple) n Mechanical stiffness: x (extensional) n Resonant frequency: 1/ x (extensional)

  • Transducers

n Piezoresistance:

  • (no scale)

n Capacitance: x (voltage to force) n Piezoelectrics: x (voltage to force) n Magnetics: x4 (current to dipole torque) n Optics:

  • (wavelength limits)
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Aaron Partridge 36 of 70 Getting In Touch with MEMS: The Electromechanical I nterface

Why Does Scaling Matter?

  • Most MEMS things get worse when made smaller

n Mass goes down cubically, so inertial sensing gets tougher. n Capacitive and piezoelectric transducers get worse linearly. n Magnetic transducers scale terribly.

  • A few things get better

n Circuits can be mounted closer, so C-strays decrease. n Resonant frequencies increase. n Reliability improves. n And (the most important) unit costs decrease.

  • Poor scaling is counterintuitive for circuits engineers.
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Aaron Partridge 37 of 70 Getting In Touch with MEMS: The Electromechanical I nterface

Remem ber This:

Know how your system scales and leverage things that work for you and not against you.

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Aaron Partridge 38 of 70 Getting In Touch with MEMS: The Electromechanical I nterface

  • MEMS Materials, Processes, and Example Applications
  • Electrical Interfaces
  • Scaling Laws
  • Packaging is Critical
  • CMOS Integration
  • How to Succeed
  • References
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Aaron Partridge 39 of 70 Getting In Touch with MEMS: The Electromechanical I nterface

Packaging is Critical

  • In circuits we don’t think about packaging, except for

n Size. n Lead inductance and resistance. n Heat dissipation.

  • In MEMS, packaging is the single most im portant thing

after the transducer selection

n How do we protect the parts in operation? n How do we handle the parts in packaging? n Can we dice the parts from the wafers? n How do we connect to the sense/ drive medium? n How do we isolate from the environment? n A million problems happen here.

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Aaron Partridge 40 of 70 Getting In Touch with MEMS: The Electromechanical I nterface

Back-end Packaging

  • Sometim es just put the MEMS

and CMOS into a package.

  • Don’t touch it!
  • Production com plications

n How to dice? n How to pick & place? n Need a clean room?

  • For som e apps, like chemical

detectors, it can work well.

ADI ADXL-50 circa 1995

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Aaron Partridge 41 of 70 Getting In Touch with MEMS: The Electromechanical I nterface

Bonded Covers

  • Wafer bonded covers protect

the MEMS elements

n Can use frit glass to glue the wafers together. n These covers can take 80%

  • f the die area.

n Building the covers can be expensive.

  • Much less expensive then

handling naked MEMS wafers.

  • The dominant technology

today.

Bosch Gyroscope circa 1999

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Deposited Thin Film Covers

  • Save space by depositing

rather than bonding covers.

  • Harder than it looks

n How to empty it out inside? n Thermal mismatches. n Contamination. n Need strength for plastic. n Limits MEMS designs.

  • Development is expensive

n Only makes sense for high- volume applications.

J.L. Lund, Hilton Head, 2002 B.H. Stark, JMEMS 2004

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Deposited Encapsulation Example

  • SiTim e (my com pany) buries

resonators under the wafer surface.

SiTime Resonator

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Stacked Die in Plastic

  • When the MEMS is

covered or encapsulated

n It can be diced like a CMOS wafer. n Pick-place, wire bond, mold, etc, all normal.

  • A low cost option when it

works for the app.

  • Applications like optical

switches can’t use this.

SiTime Oscillator Construction

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Aaron Partridge 45 of 70 Getting In Touch with MEMS: The Electromechanical I nterface

Remem ber This:

Design from the outside to the inside, and do the packaging first.

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Aaron Partridge 46 of 70 Getting In Touch with MEMS: The Electromechanical I nterface

  • MEMS Materials, Processes, and Example Applications
  • Electrical Interfaces
  • Scaling Laws
  • Packaging is Critical
  • CMOS Integration
  • How to Succeed
  • References
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Homogeneous Integration

  • Only three ways

n MEMS on CMOS. n MEMS in CMOS. n MEMS under CMOS.

  • Usually not the best approach

n Do you have the tim e and m oney? n Do you feel lucky?

  • Just a few of the problems…

n The MEMS process can change the CMOS behavior. n The CMOS process may need to be adjusted. n Price leverage of CMOS at risk. n MEMS process limitations are severe. n Wasted area increases costs for each process. n Yield issues multiply (literally).

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Homogeneous Example

3-Axis Accelerometer, Sandia

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Heterogeneous Integration

  • Usually a better approach

n Build the MEMS and CMOS die into one package. n Can be wire bonded or bump bonded. n Requires the MEMS be pre-covered for most apps.

  • Usually cheaper, faster, and more versatile

n MEMS+ CMOS can be developed in parallel. n Fewer material and temperature restrictions on the MEMS. n Shorter development times. n Many fewer surprises.

  • Be prepared to argue against a homogeneous approach

n It seems obvious, everything is getting integrated right? n Actually, heterogeneous integration is very common in RF.

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Heterogeneous Exam ple

Oscillator, SiTime

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Wafer-scale Integration

  • MEMS wafer bonded to CMOS wafer

n The wafers are bonded face-face at the MEMS fab. n Various proprietary metallurgies at MEMS fabs. n Common are gold compression and eutectics.

  • Has some good points

n Electrically close – low capacitance. n Many interconnects possible. n Usually a decent and hermetic lid. n Built in parallel, a full wafer at a time.

  • Not always a good idea

n Enforces a 1: 1 size constraint on MEMS: CMOS die. n Usually wastes space on one or both die. n Yield losses multiply.

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Wafer-scale Example

Rich Ruby, Avago, I FCS 2011 MEMS Wafer Circuits Wafer

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Remem ber This:

Never integrate MEMS on, in, or under CMOS without a very compelling reason.

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  • MEMS Materials, Processes, and Example Applications
  • Electrical Interfaces
  • Scaling Laws
  • Packaging is Critical
  • CMOS Integration
  • How to Succeed
  • References
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Aaron Partridge 55 of 70 Getting In Touch with MEMS: The Electromechanical I nterface

Problems to Manage

  • You will need to build something early

n The MEMS components will not be finished when you start your IC design. n You will not have solid data for your analysis. n If prototypes have been tested, the new parts (the real parts!) will be different. n When the MEMS is tested it will show “surprises”.

  • You will need to make your own circuit m odels

n The MEMS components will not m odeled for you. n At best you will have theory or Matlab code. n Spice? Verilog-A? CppSim? You will need to build them yourself.

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Aaron Partridge 56 of 70 Getting In Touch with MEMS: The Electromechanical I nterface

Problems to Manage

  • Specs will change in the middle of developm ent

n There are three, maybe four things in flux. n Circuits, MEMS design, MEMS process, and software. n On the applications side, marketing and sales learn too. n Rates of flux are higher than you may be used to.

  • To improve the chances your circuits work

n Understand the system in detail. n Understand the MEMS as much as possible. n Design circuits with as much flexibility as possible. n Insist on rapid prototyping cycles with test chips. n Don’t go for product too early, it can waist design effort.

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Important Points

  • Be sure you have a MEMS expert on the team

n Hire one or consult with one, but get one. n Amateurs who think they are smart enough are wrong.

  • Understand the application drivers

n How does the scaling work? n Does it require integration?

  • Consider the packaging carefully

n Design from the outside to the inside.

  • Be sure an IC engineer (you) are involved early

n System design requires balancing circuit tradeoffs. n Does a good circuits person know the details?

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Aaron Partridge 58 of 70 Getting In Touch with MEMS: The Electromechanical I nterface

Important Points

  • Build flexibility in your I C

n The MEMS will not work as expected, so roll with it. n The MEMS will be improved later, and the earlier I C should support that.

  • Insist on m any sm all learning cycles

n Use test chips to prove out the concepts. n Don’t go into product design too early.

  • Take a bigger role than IC designer

n You must be the guardian of your success.

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Aaron Partridge 59 of 70 Getting In Touch with MEMS: The Electromechanical I nterface

Aaron’s Complexity Paradox

  • The “Simple” solutions

are difficult.

  • The “Complex” solutions

are easy.

  • Move toward easy

solutions whenever possible, this means increasing complexity.

  • Embrace complexity to

succeed.

Material Device Analog Digital Microcode Firmware Software Simple Complex Easy Difficult

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Aaron Partridge 60 of 70 Getting In Touch with MEMS: The Electromechanical I nterface

Aaron’s Complexity Paradox

  • For system designers this means

n Push the problem out of MEMS whenever possible. n Don’t ever m ake the MEMS designers do som ething that

  • ne can possibly do elsewhere.
  • For IC designers this means

n You will be (or should be!) asked to push your circuits to the limit to ease the work in MEMS. n Working with MEMS will never be easy – you will always need to bring your best game.

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Complexity Management Example

  • MEMS oscillator researchers (including me!) tried to build

frequency-accurate tem perature-flat resonators.

n That didn’t work.

  • Then my colleagues and I moved the complexity into

CMOS and managed the frequency with frac-N PLLs.

n That worked!

  • Then all sorts of great things started happening – we

could include new functions in that CMOS.

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Complexity Management Example

  • SiTim e Architecture.
  • Will step through this

block by block.

CMOS Oscillator MEMS Resonator GND Prog OE /ST Vcc Clk Temperature Sensor Configuration PROM Frequency Control I/O Regs Frac-N PLL Sustaining Amp Drive

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Choose the Right Products

  • Must have a Starving Market.

(Kurt Petersen)

  • Must have an Unfair Advantage.

(Arno Penzias)

  • Why discuss this in a circuits tutorial?

n Because we engineers and scientists can almost always make our stuff work. n But failure happens when people don’t want our stuff. n Good engineering, when not needed, is wasted effort.

  • We don’t have time to waste, we are very expensive for
  • ur companies.
  • And besides, we have better things to do than engineer

stuff that people don’t need.

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Aaron Partridge 64 of 70 Getting In Touch with MEMS: The Electromechanical I nterface

Remem ber This:

We are valued not by what we do, but by what we do that makes a difference.

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Your Work Does Make a Difference

  • Technology has

fundamentally helped Humanity.

  • Engineers m ake small

contributions that are m ultiplied countless times.

  • What you do matters to

Billions of people!

Dorothea Lang, “Migrant Mother” 1936

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Thank You! Questions?

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Aaron Partridge 67 of 70 Getting In Touch with MEMS: The Electromechanical I nterface

  • MEMS Materials, Processes, and Example Applications
  • Electrical Interfaces
  • Scaling Laws
  • Packaging is Critical
  • CMOS Integration
  • How to Succeed
  • References
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References

  • A complete background to MEMS and thorough basic references

n Gregory Kovacs, “Micromachined Transducers Sourcebook”, McGraw- Hill Science/ Engineering/ Math, I SBN 0-0729-0722-3 , 1998.

  • A good general introduction of scaling and technology options

n Marc Madou, “Fundamentals of Microfabrication, The Science of Miniaturization”, CRC Press, ISBN 0-8493-0826-7, 2002.

  • A deep dive into RF MEMS and systems

n Gabriel Rebeiz, “RF MEMS: Theory, Design, and Technology”, Willey- I nterscience, I SBN 978-0471201694 , 2004.

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References

  • A solid theoretical underpinning of common MEMS devices

n Ville Kaajakari, “Practical MEMS: Design of microsystems, accelerometers, gyroscopes, RF MEMS, optical MEMS, and microfluidic systems”, Small Gear Publishing, 098-2299109, 2009.

  • The primary conference proceedings and journals

n Hilton Head, “Solid-State Sensors, Actuators, and Microsystems workshop”, Transducers Research Foundation. n Transducers, “International Conference on Solid-State Sensors, Actuators and Microsystems”, IEEE. n MEMS, “I nternational Conference on Micro Electro Mechanical Systems”, IEEE. n JMEMS, “Journal of Microelectromechanical Systems”, IEEE.

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Additional References

Capacitive transduction

  • W.C. Tang, T-C.H. Nguyen, M.W. Judy, R.T. Howe, “Electrostatic-Comb Drive of

Lateral Polysilicon Resonators”, Sensors and Actuators A: Physical, v.21, pp.328- 331, 1990.

  • A. Selvakumar, K. Najafi, “Vertical Com b Array Microactuators”, J.

Microelectromechanical Systems, v.12, pp.440–449, 2003.

  • H. Hammer, "Analytical Model for Comb Capacitance Fringe Fields", J.

Microelectromechanical Systems, v.19, pp.175-182, 2010.

  • L. Prandi, C. Cam inada, L. Coronato, G. Cazzaniga, F. Biganzoli, R. Antonello, R.

Oboe, “A Low-Power 3-Axis Digital-Output MEMS Gyroscope with Single Drive and Multiplexed Angular Rate Readout”, ISSCC 2011, pp.104-106, 2011. Piezoresistive transduction

  • A.A. Barlian, W-T. Park, J.R. Mallon, A.J. Rastegar, B.L. Pruitt, “Review:

Semiconductor Piezoresistance for Microsystems”, Proceedings of the IEEE, v.97, n.3, 2009.

  • Y. Kanda, “A Graphical Representation of the Piezoresistance Coefficients in

Silicon,” IEEE Transactions on Electron Devices, vol.29, n.1, pp.64-70, 1982.

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Additional References

  • F.N. Hooge “1/ f Noise Sources,” IEEE Transactions of Electron Devices, v.41,

n.11, pp.1926-1935, 1994.

  • J.A. Harley, T.W. Kenny, “1/ F Noise Considerations for the Design and Process

Optim ization of Piezoresistive Cantilevers”, J. Microelectromechanical Systems, v.9, pp.226-235, 2000.

  • L.M. Roylance, J.B. Angell, “A Batch Fabricated Silicon Accelerometer,” IEEE

Transactions on Electron Devices, ED-26, n.12, pp.1911-1917, 1979. Piezoelectric transduction

  • W. G. Cady, “Piezoelectricity; An Introduction to the Theory and Applications of

Electromechanical Phenomena in Crystals”, McGraw-Hill, 1946.

  • R. Ruby, P. Bradley, J. Larson, Y. Oshmyansky, D. Figueredo, “Ultra-Miniature

High-Q Filters and Duplexers Using FBAR Technology”, ISSCC 2001, p.120-121, 2001.

  • G. Piazza, P.J. Stephanou, A.P. Pisano, “One and Two Port Piezoelectric Contour-

Mode MEMS Resonators for Frequency Synthesis”, Solid-State Device Research Conference ESSCERC 2006, pp.182-185, 2006.

  • R.L. Kubena, F.P. Stratton, D.T. Chang, R.J. Joyce, T.Y. Hsu, M.K. Lim R.T.

M’Closkey, “MEMS-Based Quartz Oscillators and Filters for On-Chip Integration”, International Frequency Control Symposium, p.6, 2005.

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Additional References

Examples of less common drive and sense technologies

  • C.H. Liu, A.M. Barzilai, J.K. Reynolds, A. Partridge, T.W. Kenny, J.D. Grade, H.K.

Rockstad, “Characterization of a High-Sensitivity Micromachined Tunneling Accelerometer with Micro-g Resolution,” IEEE Journal of Microelectromechanical Systems, v.7, n.2, pp.235-244, 1998.

  • A.M. Leung, J. Jones, E, Czyzewska, J. Chen, B. Woods, “Micromachined

Accelerometer Based on Convection Heat Transfer”, International Workshop on Micro Electro Mechanical Systems, pp.627-630, 1998.

  • A. Rahafrooz, S. Pourkamali, “Fully Micromechanical Piezo-Thermal Oscillators”

IEEE Int. Electron Devices Meeting, pp.7.2.1-7.2.4, 2010.

  • M. Lutz, W. Golderer, J. Gerstenmeier, J. Marek, B. Maihofer, S. Mahler, H.

Munzel, and U. Bischof, “A Precision Yaw Rate Sensor in Silicon Micromachining,” International Conference on Solid State Sensors and Actuators, , v.2, pp.847- 850, 1997.

  • Y. Li, J. John, X. Zhang, J. Zhang, J.A. Loeb, X. Xu, “3D Neural Probes with

Combined Electrical and Chemical Interfaces”, Solid-State Sensors, Actuators, and Microsystems Workshop, Hilton Head, pp.134-137, 2010.

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Additional References

MEMS wafer-level packaging

  • Y.T. Cheng, L. Lin, and K. Najafi, "Localized Bonding with PSG or Indium Solder

as Intermediate Layer," Twelfth IEEE International Conference on Micro Electro Mechanical Systems, pp. 285-289, 1999.

  • C.H. Tsau, S.M. Spearing, and M.A. Schmidt, "Fabrication of Wafer-Level

Thermocompression Bonds," Journal of Microelectromechanical Systems, vol. 11, pp.641-647, 2002.

  • C.M. Mastrangelo and R.S. Muller, "Vacuum-Sealed Silicon Micromachined

Incandescent Light Source," Proceedings of the International Electron Devices Meeting, pp.503-506, 1989.

  • M. Esashi, S. Sugiyama, K. Ikeda, Y. Wang and H. Miyashita, “Vacuum-Sealed

Silicon Micromachined Pressure Sensors,”

  • Proc. IEEE, v.86 pp.1627–1631, 1998.
  • K.S. Lebouitz, A. Mazaheri, R.T. Howe, and A.P. Pisano, “Vacuum Encapsulation
  • f Resonant Devices Using Permeable Polysilicon,” Twelfth IEEE International

Conference on Micro Electro Mechanical Systems. MEMS'99, pp.470-475, 1999.

  • B.H. Stark, K. Najafi, “A Low-Tem perature Thin-Film Electroplated Metal Vacuum

Package,” Journal of Microelectromechanical Systems, v.13, pp.147-157, 2004.

  • A. Partridge, A.E. Rice, T.W. Kenny, and M. Lutz, "New Thin Film Epitaxial

Polysilicon Encapsulation for Piezoresistive Accelerometers," 14th IEEE International Conference on Micro Electro Mechanical Systems, MEMS 2001, pp.54-59, 2001.

  • M. Esashi, “Wafer Level Packaging of MEMS”, J. of Micromechanics and

Microengineering, iopscience, v.18, 2008.

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