darpa mto mems: generalizing the benefits of miniaturizationctnguyen/research/plenarytalks/... ·...

C. T.-C. Nguyen, TEXMEMS, 5/6/03

DARPADARPA

MTOMTO

MEMS: Generalizing the Benefits of Miniaturization

Clark T.-C. NguyenProgram Manager, MPG/CSAC/MX/HERMIT

Microsystems Technology Office (MTO)Defense Advanced Research Projects Agency

TEXMEMS’03May 6, 2003


DARPADARPA

MTOMTOOutline

• Introduction:MEMS technologyintegration with transistors: an early driver for MEMS

• Benefits of MEMSsize reductionspeed, energy conservation, complexity, economy

• Present MEMS Programs in MTONano Mechanical Array Signal Processors (NMASP)Chip-Scale Atomic Clock (CSAC)Micro Power Generation (MPG)

• What’s Next?• Conclusions


DARPADARPA

MTOMTO

Angle set by mechanical meansto control the path of light

MEMS: Micro Electro Mechanical System

• A device constructed using micromachining (MEMS) tech.• A micro-scale or smaller device/system that operates mainly

via 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., displacement, velocity, acceleration, temperature, flow

MEMS

Input:voltage, current

acceleration, velocitylight, heat …

Output:voltage, current

acceleration, velocitylight, heat, …

Control:voltage, current

acceleration velocity

light, heat, …

Transducer to Convert Controlto a Mechanical Variable (e.g., displacement,

velocity, stress, heat, …)

Transducer to Convert Controlto a Mechanical Variable (e.g., displacement,

velocity, stress, heat, …)

[Wu, UCLA]


DARPADARPA

MTOMTOOther Common Attributes of MEMS

• Feature sizes measured in microns or less

• Merges computation with sensing and actuation to change the way we perceive and control the physical world

• Planar lithographic technology often used for fabricationcan use fab equipment identical to those needed for IC’showever, some fabrication steps transcend those of conventional IC processing

MEMSTechnology

Gimballed, SpinningMacro-Gyroscope

MicromechanicalVibrating Ring Gyroscope

Signal Conditioning Circuits

80 mm

1 mm

(for 80X sizeReduction)

[Najafi, Michigan]


DARPADARPA

MTOMTO

Silicon Substrate

Glass Substrate

Bulk Micromachining and Bonding

• Use the wafer itself as the structural material

• Adv: very large aspect ratios, thick structures

• Example: deep etching and wafer bonding

Silicon SubstrateSilicon Substrate

Glass Substrate

Silicon Substrate

Metal InterconnectAnchor

MovableStructure Electrode

MicromechanicalVibrating Ring Gyroscope

1 mm

Microrotor(for a microengine)

[Najafi, Michigan] [[PisanoPisano, UC Berkeley], UC Berkeley]


DARPADARPA

MTOMTO

• Fabrication steps compatible with planar IC processing

Surface Micromachining


DARPADARPA

MTOMTO

• Completely monolithic, low phase noise, high-Q oscillator (effectively, an integrated crystal oscillator)

• To allow the use of >600oC processing temperatures, tungsten (instead of aluminum) is used for metallization

OscilloscopeOutput

Waveform

Single-Chip Ckt/MEMS Integration

[Nguyen, Howe 1993][Nguyen, Howe 1993]


DARPADARPA

MTOMTOTechnology Trend and Roadmap for MEMS

incr

easi

ng a

bilit

y to

com

pute

increasing ability to sense and act

Num

ber o

f Tra

nsis

tors

Number of Mechanical Components

100

101

102

103

104

105

106

107

108

109

100 101 102 103 104 105 106 107 108 109

AdaptiveOptics

Integrated FluidicSystems

DistributedStructural

ControlTerabit/cm2

Data Storage

Optical Switches& Aligners

InertialNavigationOn a Chip

Displays

Weapons,Safing, Arming,

and Fusing

Majority ofEarly MEMS

Devices(mostly sensors)

ADXL-50

Digital MicromirrorDevice (DMD)

ADXL-278

Future MEMSIntegration Levels

Enabled Applications

OMM 32x32

ADXL-78

CPU’s

Pentium 4

ADXRS

i-STAT 1Caliper

Phased-ArrayAntenna


DARPADARPA

MTOMTOBenefits of Size Reduction: IC’s

• Numerous benefits attained by scaling of transistors:

FasterSpeed

Higher Current DriveLower Capacitance

Higher Integration DensityLower Supply Voltage

LowerPower

Higher Circuit Complexity & Economy of Scale

• But … some drawbacks:poorer reliability (e.g., hot e- effects)lower dynamic range (analog ckts suffer)


DARPADARPA

MTOMTOExample: Micromechanical Accelerometer

• The MEMS Advantage:>30X size reduction for accelerometer mechanical elementallows integration with IC’s

xo

x

a

Acceleration

Inertial Force

Spring

Proof Mass

Basic Operation Principle

400

μm

Analog Devices ADXL 78

Displacement

maFx i =∝

Tiny mass means small output need integrated transistor

circuits to compensate

Tiny mass means small output need integrated transistor

circuits to compensate


DARPADARPA

MTOMTO

DisplaysPhased-ArrayAntenna

Technology Trend and Roadmap for MEMSin

crea

sing

abi

lity

to c

ompu

te


Num

ber o

f Tra

nsis

tors


100

101

102

103

104

105

106

107

108

109

100 101 102 103 104 105 106 107 108 109

AdaptiveOptics



ControlTerabit/cm2

Data Storage




and Fusing



ADXL-50


ADXL-278



OMM 32x32

ADXL-78

CPU’s

Pentium 4

i-STAT 1

ADXRS

Analog Devices ADXRSIntegrated Gyroscope

Adv.: small sizeAdv.: small size

OMM 8x8 OpticalCross-Connect Switch

Adv.: faster switching, low loss, larger networks

Adv.: faster switching, low loss, larger networks

Adv.: low loss, fast switching, high fill factor

Adv.: low loss, fast switching, high fill factor

TI Digital Micromirror Device

Caliper Microfluidic Chip

Adv.: small size, small sample, fast analysis speed

Adv.: small size, small sample, fast analysis speed

Caliper


DARPADARPA


incr

easi

ng a

bilit

y to

com

pute


Num

ber o

f Tra

nsis

tors


100

101

102

103

104

105

106

107

108

109

100 101 102 103 104 105 106 107 108 109

AdaptiveOptics



ControlTerabit/cm2

Data Storage




and Fusing



ADXL-50


ADXL-278



OMM 32x32

ADXL-78

CPU’s

Pentium 4

incr

easi

ng p

ower

con

sum

ptio

n

ADXRS

i-STAT 1Caliper

Lucrative Territory



DARPADARPA

MTOMTOBenefits of Size Reduction: MEMS

• Benefits of size reduction obviated by IC’s in elect. domainsize reduction speed, low power, complexity, economy

• MEMS: enables a similar concept, but …

MEMS extends the benefits of size reductionbeyond the electrical domain

Performance enhancements for applicationdomains beyond those satisfied by electronics

in the same general categories Speed

Power ConsumptionComplexity

Economy

Frequency , Thermal Time Const. Actuation Energy , Heating Power Integration Density Batch Fab. Pot. (esp. for packaging)


DARPADARPA

MTOMTO

Nano Mechanical Array Signal Processors (NMASP)


DARPADARPA

MTOMTOExample: Scaling Guitar Strings

Guitar String

Guitar

Vibrating “A”String (440 Hz)Vibrating “A”

String (440 Hz)

High Q

440 Hz Freq.

Vib.

Am

plitu

de

Low Q

r

ro m

kfπ21

=

Freq. Equation:

Freq.

Stiffness

Mass

fo=8.5MHzQvac =8,000

Qair ~50

μMechanical Resonator

Performance:Lr=40.8μm

mr ~ 10-13 kgWr=8μm, hr=2μmd=1000Å, VP=5VPress.=70mTorr

[Bannon 1996]


DARPADARPA

MTOMTO

• Below: 7.81 MHz, 2-resonator, CC-beam μmechanical filter in POCl3-doped polysilicon

Spring-Coupled μMechanical Filter

Design:Lr=40.8μm, Wr=8μm, h=2μm,

Ls12=20.35μm, VP=35V

Design:Lr=40.8μm, Wr=8μm, h=2μm,

Ls12=20.35μm, VP=35V

Performance: (70 mTorr vacuum)fo=7.81 MHz, BW=18 kHz, Qres=6,000

PBW=0.23%, Ins. Loss < 1 dB

Performance: (70 mTorr vacuum)fo=7.81 MHz, BW=18 kHz, Qres=6,000

PBW=0.23%, Ins. Loss < 1 dB

Mechanical, not electrical, interconnect reduced

susceptibility to EMI

Mechanical, not electrical, interconnect reduced

susceptibility to EMI[Bannon, Nguyen 1996]


DARPADARPA


incr

easi

ng a

bilit

y to

com

pute


Num

ber o

f Tra

nsis

tors


100

101

102

103

104

105

106

107

108

109

100 101 102 103 104 105 106 107 108 109

AdaptiveOptics



ControlTerabit/cm2

Data Storage




and Fusing



ADXL-50


ADXL-278



OMM 32x32

ADXL-78

CPU’s

Pentium 4

incr

easi

ng p

ower

con

sum

ptio

n

ADXRS

i-STAT 1Caliper

Lucrative Territory



DARPADARPA

MTOMTONanomechanical Vibrating Resonator

• Constructed in SiC material w/ 50 nm Al metallization for magnetomotive pickup

192.0 192.5 193.0 193.5 194.00

200

400

600

800

1000

1200

Mag

neto

mot

ive

Res

p. [n

V]

Frequency [MHz]

Design/Performance:Lr =3 μm, Wr =150 nm, h= 259 nm

fo=193 MHz, Q =1,000 @ 4K

Lr

Wr

[Roukes, Zorman 2000]

h


DARPADARPA

MTOMTO

Scaling-Induced Performance Limitations

Mass Loading Noise

• Differences in rates of adsorption and desorptionof contaminant molecules

mass fluctuationsfrequency fluctuations

Temperature Fluctuation Noise

• Absorption/emission of photons

temperature fluctuationsfrequency fluctuations

ContaminantMolecules

mass ~10-13 kg

mk

2π1

of =

Photons

volume ~10-15 m3

• Problem: if dimensions too small phase noise significant!• Solution: operate under optimum pressure and temperature

[J. R. Vig, 1999]


DARPADARPA

MTOMTO

733 MHz Self-Aligned Radial Contour-Mode Disk μMechanical Resonator

• Self-aligned stem for reduced anchor dissipation• Polysilicon electrodes for better gap stability• Q > 6,000 seen even in air (i.e., atmospheric pressure)!• Below: 20 μm diameter disk

PolysiliconElectrode


R

Self-Aligned Stem

GroundPlane

fo=433MHzQ=4,066

μMechanical DiskResonator

-105

-100

-95

-90

-85

732 732.5 733 733.5 734

Frequency (MHz)

Tran

smis

sion

(dB

)

[Wang, Nguyen 2002]

fo = 732.9MHzQ = 7,330 (vac)

Design/Performance:R=10μm, t=2.1μm, d=800Å, VP=6.2Vfo=732.9MHz (2nd mode), Q=7,330

Q = 6,100 (air)


DARPADARPA

MTOMTO

1.14-GHz Self-Aligned Radial Contour-Mode Disk μMechanical Resonator

• Self-aligned stem for reduced anchor dissipation• Operated in the 3rd radial-contour mode• Q > 1,500 seen even in air (i.e., atmospheric pressure)!• Below: 20 μm diameter disk



R

Self-Aligned Stem

GroundPlane

μMechanical DiskResonator

[Wang, Nguyen 2003]

Design/Performance:R=10μm, t=2.1μm, d=800Å, VP=6.2V

fo=1.14 GHz (3rd mode), Q=1,595

-84-83-82-81-80-79-78-77

1138.5 1139.5 1140.5 1141.5

fo = 1.14 GHzQ = 1,595 (vac)Q = 1,583 (air)

Tran

smis

sion

[dB

]

Frequency [MHz]


DARPADARPA

MTOMTOBenefits of MEMS: Size Reduction

TransistorChips

TransistorChips

QuartzCrystalQuartzCrystal

IF Filter(SAW)

IF Filter(SAW)

InductorsCapacitorsResistors

InductorsCapacitorsResistors IF Filter

(SAW)IF Filter(SAW)

RF Filter(ceramic)RF Filter(ceramic)

MEMSMEMSTechnologyTechnology

Single-ChipTransceiver


DARPADARPA

MTOMTO

Chip-Scale Atomic Clocks (CSAC)


DARPADARPA

MTOMTOCSAC: A Disruptive Technology

State-of-Practice

State-of-Research

HP 5071AVol: 29,700 cm3

Power: 50 WAcc: 5×10–13

Datum R2000Vol: 9,050 cm3

Power: 60 WAcc: 5×10–11

Temex RMOVol: 230 cm3

Power: 10 WAcc: 1×10–11

NG MC250Vol: 27 cm3+

Power: 220 mW+Acc: 1.5×10–11

KerncoVol: 20 cm3+

Power: 300 mW+Acc: 1×10–11

NIST CPT cellVol: 30 cm3+

Power: 300 mW+Acc: 1×10–11

NISTNIST-- F1F1

VolVol: ~3.7 m: ~3.7 m33

Power: ~500 WPower: ~500 WAcc: Acc: 3.83.8××1010––1515

CSACCSACVolVol: 1 cm: 1 cm33

Power: 30 Power: 30 mWmWStab: Stab: 11××1010––1111


DARPADARPA

MTOMTOChip-Scale Atomic Clock Summary

• Goal: create atomic time and frequency reference units with±1µs/day accuracy< 1 cm3 volume< 30 mW power consumption

• Motivation: enable ultra-miniaturized (wristwatch in size) and ultra low power time and frequency references for

high-security communicationsjam-resistant GPS receivershigh-confidence identification of friends and foesultra-sensitive radar (for slow moving objects)efficient spectrum utilization for increased # of usersradio emitter locatorsimproved denial of systems to unauthorized userslonger autonomy period (radio silence interval)missile and munitions guidance


DARPADARPA

MTOMTOGlobal Positioning Satellite Receiver

• Operation based on trilateration: distances to satellites with known locations are used to interpolate the receiver location

d1

d2

L1

L3

Satellite 1

Satellite 3

• Knowledge of satellite locations (L1, L2, and L3) and distances (d1, d2, and d3) to the GPS receiver GPS receiver location

L2

Satellite 2

d3


DARPADARPA

MTOMTOGlobal Positioning Satellite Receiver

• Distance determination based on lags between pseudorandom signals generated by the satellite and receiver

L1

L2

L3

Satellite 1

Satellite 2

Satellite 3

time

ReceiverGenerated

PseudorandomCode

SatelliteTransmitted

PseudorandomCode

Time Lag Between Received And Local

Pseudorandom Codesd3

The more accurate the clock, the better

and faster the determination of

distance (& location)

The more accurate the clock, the better

and faster the determination of

distance (& location)

d1

d2

d3


DARPADARPA

MTOMTOAccurate Portable Timekeepers/Refs.

• Stability quite good at freqs. around 1 kHz

• {fm=1kHz} = -140dBc/Hz

High-Q Oscillators• Tank Q ~ tens of thousands• Example: crystal oscillator

• Quartz: vibrating mechanical resonance high Q, stable

10MHz Excellent stability at offset

frequencies ~1kHz

Excellent stability at offset

frequencies ~1kHz

Accuracy (@ tiny offset freqs.) good, but not good enough for

some applications

Accuracy (@ tiny offset freqs.) good, but not good enough for

some applications

Shear Mode


DARPADARPA

MTOMTOAtomic Clock Principle & Design

• Problem: μwave cavity dictates size133Cs

m = 0f = 4

m = 0f = 3

m = 1

852.11 nm

852.11 nm

ν = ΔE/ħ= 9 192 631 770 Hz

9 192 631 770 Hz

133Cs vapor at 10–7 torr

852.11 nm laserPhoto

detectorµ-wave cavity

Microwave at9 192 631 770 Hz

OpticalOptical--Microwave Atomic ClockMicrowave Atomic Clock

µ-wave f

852.11 nm laserModulated at

9 192 631 770 HzPhoto

detector133Cs vapor at 10–7 torr

Mod f

AllAll--Optical Atomic ClockOptical Atomic Clock• Solution: optical excitation (CPT)

• Frequency determined by an atomic transition energy

InterrogatingLaser

InterrogatingLaser

AbsorptionAbsorption

HyperfineTransitionHyperfineTransition

Input EnergyInput Energy


DARPADARPA

MTOMTOAtomic Clock System Requirements

• Atomic clocks are extremely accurate excellent long-term stability (i.e., excellent close-to-carrier phase noise)

• Problem: very low output power poor short-term stability• Solution: lock to another stable reference with larger output

power capability (e.g., microwave source locked to crystal) 852.11 nm laser

Modulated at9 192 631 770 Hz

PhotoDetector


Mod f

VCXOVCO

÷ N MicrowaveSource Voltage-Controllable

Crystal OscillatorVoltage-Controllable

Crystal Oscillator

10 MHz4.6 GHz


DARPADARPA

MTOMTOChallenge: Miniature Atomic Cell

• Advantage of Size Reduction:lower heating power: can use longer, thinner supports & smaller volume better thermal isolation

• Consequence of Size Reduction:stability compromise:

stability reduction seen as increase in resonance linewidth• Solutions: (to the above)

buffer gases to prevent wall collisionswall coatings to “cushion” collisions

Cell Size Surface-to-Volume Ratio

Atomic CollisionsWith Cell Walls Stability

LargeVaporCell

TinyVaporCell


DARPADARPA

MTOMTOChip-Scale Atomic Clock

• Key Challenges:cell design for maximum QGHz high-Q reference resonatorthermal isolation for low power

Cs or Cs or RbRbGlassGlassDetectorDetector

VCSELVCSEL

SubstrateSubstrate

GHzGHzResonatorResonatorin Vacuumin Vacuum

MEMS andMEMS andPhotonic Photonic

TechnologiesTechnologies

Chip-ScaleAtomic Clock


VCXOVCO

÷ N MicrowaveSource

10 MHz4.6 GHz

Laser

Vapor CellVapor Cell

PhotoDetector

Atomic Clock Concept

Mod f852.11 nm


DARPADARPA

MTOMTO

Micro Power Generation (MPG)


DARPADARPA

MTOMTOMPG Program in a Nutshell

• Objective: Generate power at the micro scale to enable standalone micro sensors and micro actuators with wireless communication to realize new systems and strategies for weapons systems, processes and battlefield environments

Sensors

Fuelstorage

Actuators ASIC/CPURF/Optical

Comm

Heat engine/Fuel reformer

Thermal/Exhaustprocessor 1 mm

TE Converter/Fuel cell

• Approach: Harness fuels with higher energy density

0 2 4 6 8 10 12 14Energy Density (kW-hr/kg)

PropaneMethaneGasoline

DieselEthanol

MethanolLi Battery


DARPADARPA

MTOMTODistributed Autonomous Sensor Networks

AutonomousSensor Node

• Typical Power Requirement: 10-100 μW continuous, 30 mWpulses 4 times per day (on average)


DARPADARPA

MTOMTOApproach: Fuel Cell

• Common elements among fuel cells:fuel storage/deliveryanode and cathode electrodescatalyst to dissociate fuel (e.g., into H+ and e-) at anode and combine products at cathodeion exchange medium (i.e., electrolyte)

Fuel Storage

Vout

ChemicalEnergy

FuelDelivery

ChemicalEnergy

ElectricalEnergyElectrolyte

PorousAnode

Electrode

PorousCathode

Electrode

Catalyst(e.g., platinum)

Load

+

-H+

e-

H+

e-

CO2O2

H2O

ElectricalEnergy

30–40% eff. with reformer


DARPADARPA

MTOMTOApproach: Micro Engine

• Common elements among micro engines:fuel storage/delivery systemcombustion to generate heatactuator (e.g., rotor): convert heat to mechanical motionelectromechanical transducer: convert mechanical motion to electricity

Fuel Storage CombustionChamber

Heat

Actuator(e.g., rotor, piston)

ElectromechanicalTransducer

ElectricityChemicalEnergy

EvaporatedFuel MotionExpanding Gas

ChemicalEnergy

ElectricalEnergy

MechanicalEnergy 1

MechanicalEnergy 2

20% eff.


DARPADARPA

MTOMTOEngine Types: Piston vs. Rotary

• Dominates automobile engine designs

efficientinexpensiveeasy to refuel

• Not ideal for MEMS

• Several combustion strokes occurring at once

• Fewer moving parts: no valves, camshafts, cams, …

• Smoother operation: no reciprocating piston

• More conducive to MEMS!

Piston Engine Rotary Engine


DARPADARPA

MTOMTOMEMS Rotary Engine Power System

Apex

Housing Top

Housing Bottom

Apex

Housing Top

Housing Bottom

Conformal SiCSurface Layer

Si Deep RIE

MEMSREPS

Package

Packaging

Soft MagneticPole Integration

IntegratedGenerator

Fuel Evaporator

Micro-RotaryEngine

Ultra-Thick DRIEProcess (900 μm)

Apex & FaceSeal Modeling

IntegratedApex Seal

PhaseEruption

EngineControl

Unit ASIC

• To Date: several components now micro-fabricated

[Pisano, UC Berkeley]


DARPADARPA

MTOMTO

What’s Next?(numerous possbilities)


DARPADARPA

MTOMTO

MicromechanicalDevice

Microplatform

Substrate

Vibration IsolatingFilter NetworkHeater

TemperatureSensor

VacuumCap

VacuumVacuum

• Objective: attain superior performance and lifetime of MEMS devices via localized control of their operating environments

• Approach: harness MEMS technology to achieve adaptive integrated micro-chambers that actively respond to changes (e.g., temperature, vibration) in their surroundings so as to provide ideal operating environments for contained devices

• Example: micro-oven control

Harsh Environment Robust Micromechanical Technology (HERMIT)


DARPADARPA

MTOMTOMicro-Scale Oven-Control Advantages

• The micro-scale advantages:orders of magnitude smaller sizeorders of magnitude less power consumptionorders of magnitude faster thermal time constants

SuspendedPlatform

Vibration IsolationSuspension

T Sensor Heater

OscillatorCircuit

FeedbackControl Ckts.

HeaterT Sensor

Quartz Xstal

Rth= 160 K/W, Cth= 3.75 J/KP (@ 50oC) = 2 W, τ = 600 s

Rth= 160 K/W, Cth= 3.75 J/KP (@ 50oC) = 2 W, τ = 600 s

Rth= 100,000 K/W, Cth= 3x10-7 J/KP (@ 50oC) = 3 mW, τ = 30 ms

Rth= 100,000 K/W, Cth= 3x10-7 J/KP (@ 50oC) = 3 mW, τ = 30 ms

P RthCth

T = P x Rth

Cth ~ volume

Rth ~ support lengthX-section area

Macro-Scale Micro-ScaleT stability ~10-8


DARPADARPA

MTOMTO

Conclusions


DARPADARPA

MTOMTOConclusions

• MEMS are micro-scale or smaller devices/systems that operate mainly via a mechanical or electromechanical means

• MEMS extend the advantages of size reduction beyond the electrical domain, to the mechanical domain

higher speedlower energy consumptionhigher complexity/functionalitylower cost

• What’s next? ideas that capitalize on the advantages of size reduction; multitude of possibilities:

Micro Gas Analyzers for chemical/biological detectionOn-Chip Data Storage for system on a chip applicationsMicro Cryogenic Cooling for targeted on-chip coolingMicro Propulsion for picosatellites and micro-UAVsNano/Micromechanical Circuits for enhanced circuits

… limitless possibilities …

darpa mto mems: generalizing the benefits of miniaturizationctnguyen/research/plenarytalks/... ·...

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