lecture 0 mems (microelectromechanical systems) : the...

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Lecture 0Lecture 0

MEMS (Microelectromechanical Systems) : MEMS (Microelectromechanical Systems) : The Leading Technology in the 21st CenturyThe Leading Technology in the 21st Century

• Introduction

• Applications

– Micro inertial sensors

– Display devices

– Information storage devices

– MEMS-based RF communication devices

마이크로시스템기술개론 MEMS_Lect00_1

– Micro chemical testing systems

• Conclusions

What is MEMS ?What is MEMS ?Microelectromechanical systems (MEMS) are integrated micro devices

or systems combining electrical and mechanical components fabricated using integrated circuit (IC) compatible batch-processing techniques and range in size from micrometers to millimeters. Current MEMS applications include

l t h i l d fl i ti ti laccelerometers, pressure, chemical, and flow sensors, micro-optics, optical scanners, and fluid pumps. MCNC, North Carolina


Vibrating micro gyroscope

130㎛130㎛5㎛5㎛

Thick PR mold for Electroplating

2

Fabrication Process of Micro CantileverFabrication Process of Micro Cantilever

InsulatorEtch Mask

(a)

(b)

(d)

(e)

Sacrificial layer

Structure layer


(c) (f)

Insulator Sacrificial layerStructure layer Etch Mask

Microfabricated GearMicrofabricated Gear

A tick is on a 300-micrometer diameter gear.


From Sandia National Laboratories

3

Conventional vs. MEMS Inertial Measurement Conventional vs. MEMS Inertial Measurement UnitsUnits


From DARPA

Mass Spectrograph on a ChipMass Spectrograph on a Chip


Mass spectrograph on a chip, which integrates vacuum pumps, ionizer,

an ion detector array, and control electronics onto a monolithic chip

architecture From DARPA

4

Conventional ApplicationsConventional Applications

Application of gyroscope-Inertial Navigation System-GPS-Suspension operation of cars -Compensation of movement of

the hands for camcorder -Self-operation of robots

Application of gyroscope-Inertial Navigation System-GPS-Suspension operation of cars -Compensation of movement of

the hands for camcorder -Self-operation of robots


-Head Mounted Display(HMDS)-Night Vision Goggle(NVG)-Flight simulator

-Head Mounted Display(HMDS)-Night Vision Goggle(NVG)-Flight simulator

Gyroscope ApplicationsGyroscope Applications

1

10

Airbags

Anti-Collision Systems

Active Suspension

Anti-Skid

Free Space Pointers

Vehicle

Homec)

0.01

0.1

Free Space Pointers

Remote Control Devices

Video Camera

Navigation(GPS)

Toys and Sports Equipment(Varies)

Machine Control

Attitude Control of Flying Objects

Automatic Guided Vehicles

Stabilized Platforms

Robotics

Angular Vibration measurement(Varies)

Monitoring of Body Movement

Vibration Diagnotics

Industry

Medical

Res

olut

ion

(deg

/sec


0.001

1 10 100 1000

Vibration Diagnotics

Control for Paralysed Patients

Surgical Instrument

Wheel Chairs

Range (deg/sec)

5

State of ArtState of Art

Commercial product1. SiVSGCommercial product1. SiVSG1

10

c)

2. JPL/UCLA3. Systron donner4. Bosch product

2. JPL/UCLA3. Systron donner4. Bosch product

The othersUniversityThe othersUniversity

0.01

0.1

1

11

22

33

Res

olut

ion

(deg

/sec

44

SNUSNUHigh resolution& large range

High resolution& large range


yy

0.0011 10 100 1000

Maximum measure range (deg/sec)

Microgyroscope StructureMicrogyroscope Structure

Inner gimbalInner gimbal

Driven mode flexureDriven mode flexureFixed anchorFixed anchor

Sensed mode flexureSensed mode flexure

Sensed electrode(+)Sensed electrode(+)Outer gimbalOuter gimbal

Rebalancing electrodeRebalancing electrode

Sensed electrode(-)Sensed electrode(-)


Balancing electrodeBalancing electrodeRebalancing electrodeRebalancing electrode

Comb driveComb drive

Schematics of in-plane vibratory gimbaled microgyroscope

Schematics of in-plane vibratory gimbaled microgyroscope

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Structure of Micro GyroscopeStructure of Micro Gyroscope

Fixed anchorDriven mode flexure

Sensed electrode(+)Inner gimbal

Sensed mode flexure Vibrating gyroscope:

Sensed mode

Sensed electrode(-)

Tuning electrode

Coriolis accelleration

Capacitive driving and sensing

Stability: 4 degrees per hour


Driven mode

Angular rateOuter gimbal

Comb drive

Rebalancing electrode

Principle & FabricationPrinciple & Fabrication

yx

z

Driving mode(2.036㎑) Sensing mode(2.720㎑)

Angular rate(z-axis)

Coriolis force

sensed electrodescomb drive

attitude correction & tuning


balancing

Fabricated microgyroscope Sensor die with needle’s eye CDIP packaged sensor chip

• Sensor area - 1mm x 1.1mm• Sensor area - 1mm x 1.1mm

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Micro Mirror ArrayMicro Mirror Array

Mirror plate


Torsional springMirror post

Scheme of Display Using Mirror ArrayScheme of Display Using Mirror Array

screen inscreen in screen out screen inscreen in screen out


V onV offV onV off V on V off

8

Micro Mirror Array ProjectorMicro Mirror Array Projector


from IEEE Spectrum

Fabricated Micro MirrorsFabricated Micro Mirrors


From T.I. From T.I.

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What is adaptive optics ?What is adaptive optics ?

Wavefront Sensor

Image Camera

Control System

Beam Splitter


Deformable Micro MirrorIncoming

Image

Spatial Light Modulator Array Spatial Light Modulator Array for Amplitude & Phase Modulationfor Amplitude & Phase Modulation

Mirror plate(100×100 μm2 )Torsional springfor amplitude modulation Electrostatic actuation

4μm

6μm

Upper electrode

Bottom electrode

Double crab leg spring

for amplitude modulation

Support post

Piston plus tilt mode operations are available.

Specification

Maximum vertical deflection length : 4 ㎛

Maximum rotation angle :


Schematic view of designed micro SLM

Double crab leg springfor phase modulation ±4.5°

Application: adaptive optics

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Fabrication Process & ResultsFabrication Process & Results

Bottom electrode forming

Spring structure define

1st post hole for spring structure forming by RIE

Mi Al d iti (10000Å)

SEM view of fabricated micro SLM array


Si Thick PR SiO2 Al

Mirror Al deposition (10000 Å)

Sacrificial layer removal by RIE

SEM side view of fabricated micro SLM array

Amplitude SLMAmplitude SLM

Two dimensional optical scanner (Ming. C. Wu et. al)

St d d th l l ili ff d b MCNC


• Standard three-layer polysilicon process offered by MCNC• Electrostatically driven micro mirror• Torsion spring structure• Large area (400 × 400 µm²), Large angle (±14º)• Pull in voltage : 70V, Resonant freq.: 1.5kHz

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Amplitude SLMAmplitude SLM

Laser-beam positioning mirror (R. S. Muller et. al)

• Beam steering mirror forscanning or off-chip beampositioning.

• Driven by comb actuator• Mirror size : (500 × 500 µm²)• Up to 20 degrees of angular

range of motion• Resonant freq : 29 kHz


Resonant freq.: 29 kHz

Scanner for off-chip beam positioning

MicroMicro--Optical ComponentsOptical Components


from UCLA

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MicroMicro--Optical Bench on a ChipOptical Bench on a Chip

from UCLA


from UCLA

Free-space micro-optical disk pickup head consists of a prealignedsemiconductor laser, a collimating lens, a beamsplitter, a focusing lens,a 45o upward-reflecting mirror and a 45o downward-reflecting mirror.

RF MEMS ProductsRF MEMS Products

• Low loss transmission line

• Variable capacitor and inductor

• RF filter

• VCO(Voltage-controlled oscillator)

• Phase shifter

• Movable antenna


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Advantage of RF MEMSAdvantage of RF MEMS

• Improvement of the power efficiency

– Replace electrical circuits with electromechanical signal processing

• Simply integrated with transmission lines

– Replace discrete, off-chip components (switch, varactor, inductor)

with micromachined elements

→Monolithic implementations are possible.


• Reduction of the fabrication cost, size, and complexity

Overlay CPW LINEOverlay CPW LINEPropagation region of EM waveSignal line

Ground line

A

A A´

A´

Signal line

Schematic view of OCPW line

• EM wave propagation along the overlapped area between overhanging signal line and ground plate– Reduction of the substrate

dielectric loss


Ground plate

Fabricated OCPW transmission line

dielectric loss– Reduction of conductor loss by

widening the center signal line– Wide distribution of the edge

current density

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Tunable TwoTunable Two--pole Resonators Filterpole Resonators Filter-- TwoTwo--pole Resonators Filterpole Resonators Filter

Micromachined variable capacitor

P t 2

RF choke

P t 1

DC bias source Micromachined variable capacitor

Half λ line• Using 2-pole resonators

• Frequency shift with micromachined variable


Port 2Port 1

Topology of two-pole resonators filter

micromachined variable capacitors connected to half wavelength resonators

• 6.2% center frequency shift from 30.6 GHz to 28.7 GHz

Fabricated FilterFabricated Filter

Cantilever beam

Variable capacitors 200 ㎛ ⅹ200 ㎛ • Fabricated with 2 ㎛-thick electroplated gold

structures on the glass (Corning #7740)

substrate

• Fabricated with 2 ㎛-thick electroplated gold

structures on the glass (Corning #7740)

substrate

λ/4 stub

Port2

Dielectric layer

Air bridges W: 20 ㎛, L: 190 ㎛

substrate

• Overhanging structures suspended 6㎛

substrate

• Overhanging structures suspended 6㎛


DC bias line

DC voltage pad

Port1Air bridge

Top view of two-pole resonators filter

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ext. chemicalprocess


Albert van den Berg, University of Twente


Evolution of LOC from Chemical SensorsEvolution of LOC from Chemical Sensors

chemicalcompound

sensor actuator

microfluidics

sensor actuator

microfluidics

chemical process

sensor

chemicalcompound

sensor actuator

chemicalcompound


electronic control electronic controlelectroniccontrol

electronic control

a) sensor b) sensor/actuator c) microanalysis system d) microchemical system

Process of integration of sensors, actuators, fluidics, and reactors into a microchemical system

Technologies Comprising LOCTechnologies Comprising LOC

Microfluidics Microelectronics

Micro Chemical

Processing Unit (micro

CPU)Integrated Detection

MicrochemistryMicrofabrication

Bioinformatics


Desktop Synthesizer

and Screener- David Sarnoff Research Center

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Gene Chip on MarketsGene Chip on Markets

400,000 probes/1.28 cm2

• Affymetrix gene chip kit

Gene diagnostic chip

Fluorescence scanning

• Nanogen chip


• CMS chip and scanner

Reagent A

hν

Absorption - 495 nmEmission - 520 nm

Window for fluorescencemeasurement

Micro ELISA Fluidic SystemMicro ELISA Fluidic System

Rinse Reagent B

FITC

Li k l (GAPS)

Virus or Cell (for detection)

Ab*FITC (or enzyme)

Blocking agentPrimary Ab(probe)

Waste


1. ELISA chip loading

2. Washing & samples are injected

3. Ab*FITC is injected

4. Fluorescence detection

Glass substrateLinker layer(GAPS)

Reactor ELISA chip loaded

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DNA ChipDNA Chip

DNA chip

- DNA sequencingDNA -double helix strands

DNA sequencing

- Micro fabrication

(Micro stamping or synthesis by photolithography)

- One chip assay

Performance is improved

Assay time and cost is


Assay time and cost is reduced

Easy manipulation

Assembly of Oligonucleotide Probes Using Assembly of Oligonucleotide Probes Using PhotolithographyPhotolithography

Ultra Violet lightDNA monomer ;A-X, T-X, G-X, C-X

Protection group;-XMask1

T-X

(a)

C-X

(b) (c)Ultra Violet light

ox

ox

ox

ox

oxx

Ho ox

ox

ox

Ho Tx x

ox

ox

oxx

T

Tx x

ox

ox

oxx

T Tx x

oxx

T Cx

Cx

TA C

CT

GGG

T

A T A TC

C

Mask2


Process repeat(d) (e) (f)

• 4 lithographies are required for a base• 64 lithography process are required for 16 base; lots of mask!!!

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UV illuminatorA

Maskless Photolithography Using Maskless Photolithography Using Micromirror ArrayMicromirror Array

Micromirror On state

Micromirror Off state Selective

lithography

A11 A12 A13

A21 A22 A23

A31 A32 A33

A

A’

Fabricated biochip


Micromirror array

(Virtual mask)

biochip

• MEMS technology is originated from semiconductor technology.

• Key components of information technology and biotechnology are

ConclusionsConclusions

y p gy gy

fabricated using MEMS technology.

• It is expected that MEMS market grows annually 20 - 30 % from 1998

to 2003.

• MEMS products are applied to micro inertial sensors, display devices,

information storage devices, MEMS-based RF devices and micro


chemical testing system.

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