Overview of MEMS

7/25/2019 Overview of MEMS

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Introduction to MEMS Technology

Dr. S. L. Pinjare

[email protected]!"#0$%
mailto:[email protected]:[email protected]


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Topics &hat is MEMS

&hy MEMS' (o) are MEMS Made

The (istory o* MEMS

+hallenges o* MEMS

MEMS ,pplications

MEMS mar-ets MEMS +,D

MEMS in ,ction

Summary


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&hat is MEMS'

Micro-Electro-Mechanical Systems

Three MEMS lood pressure

sensors on a head o* a pin /Photo

courtesy o* Lucas o1aSensor2

3remont2 +,4


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MEMS' MEMS e1ol1ed *rom the Microelectronics re1olution

MEMS or MST' 6nited States the technology is -no)n as MicroElectroMechanical Systems MEMS

In Europe it is called Microsystems Technology 7 MST

In 8apan2 Micromachines

&or-ing De*inition9

What's in a name? ... A rose by any othername would smell as sweet.

W. Shakespeare inRomeo and Juliet


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MEMS'

MEMS is simultaneously a toolo:2 a physical product2 and a

methodology2 all in one9

It is a port*olio o* techni;ues and processes to design and create

miniature systems.

It is a physical product o*ten specialiMEMS is a )ay o* ma-ing things2?

reports the Microsystems Technology **ice o* the 6nited States

D,AP, /$4. These >things? merge the *unctions o* sensing and actuation )ith

computation and communication to locally control physical

parameters at the microscale2 yet cause e**ects at much grander

scales.


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MEMS' , MEMS is a de1ice made *rom e:tremely small parts Bthough a uni1ersal

de*inition is lac-ingC.

MEMS products possess a numer o* distincti1e *eatures. miniature emedded systems

in1ol1ing one or many micromachined components or structures.

enale higher le1el *unctions2 y themsel1es they may ha1e limited utility

integrate smaller *unctions together into one pac-age *or greater utility

merging an acceleration sensor )ith electronic circuits *or sel*

diagnosticsC.

cost ene*its

directly through lo) unit pricing or indirectly y cutting ser1ice and

maintenance costs.


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MEMS device and biologicalmaterial

Size Comparison


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MEMS Si


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MEMS as a MicroSystem

, microsystem might comprise

the *ollo)ing9

, sensor that inputs

in*ormation into the systemF

,n electronic circuit that

conditions the sensor signalF

,n actuator that responds to

the electrical signals

generated )ithin the circuit.

oth the sensor and the actuator

could e MEMS de1ices in

their o)n right.


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MEMS'

, MicroElectroMechanicalSystem BMEMSC contains othelectrical and mechanicalcomponents )ith characteristicsi


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MEMS' Microelectronics

The microelectronics act as the

GrainG o* the system.

It recei1es data2 processes it2 and

ma-es decisions.

The data recei1ed comes *rom

the microsensors in the MEMS.


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MEMS' Microsensors

The microsensors act as the

arms2 eyes2 nose2 etc.

They constantly gather data

*rom the surrounding

en1ironment and pass this

in*ormation on to themicroelectronics *or

processing.

These sensors can monitor

mechanical2 thermal2iological2 chemical2 optical

and magnetic readings *rom the

surrounding en1ironment.


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MEMS' Microactuators

, micro actuator acts as a s)itch or

a trigger to acti1ate an e:ternalde1ice.

,s the microelectronics is

processing the data recei1ed *rom

the microsensors2 it is ma-ingdecisions on )hat to do ased on

this data.

Sometimes the decision )ill

in1ol1e acti1ating an e:ternal

de1ice. I* this decision is reached2 the

microelectronics )ill tell the micro

actuator to acti1ate this de1ice.


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MEMS' Microstructures BMechanicalC

Due to the increase in

technology *or micromachining2

e:tremely small structures can e

uilt onto the sur*ace o* a chip.

These tiny structures are called

micro structures and are actuallyuilt right into the silicon o* the

MEMS.

,mong other things2 these

microstructures can e used as1al1es to control the *lo) o* a

sustance or as 1ery small *ilters.


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MEMS'


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&hy MEMS


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&hy MEMS'

Small de1ices9

3ast mechanical response9

tend to mo1e or stop more ;uic-ly due to lo) mechanicalinertia.

Ideal *or precision mo1ements and also *or rapid actuation.

Encounter less thermal distortion and mechanical 1iration dueto lo) mass.

(a1e higher dimensional staility at high temperature due tolo) thermal e:pansion.

,re particularly suited *or iomedical and aerospaceapplications eing minute in si


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&hy MEMS'

less space This allo)s the pac-aging o* more *unctional

components in a single de1iceHsystem.

less material Means lo) cost o* production and

transportation.

Lo) po)er udget2 *aster de1ice2increased selecti1ity and sensiti1ity2)ider dynamic range.

minimal in1asi1e Be.g.2 micro*aricated

needlesC Potential to integrate )ith circuits

The aility to *aricate array o* de1ices

atch *arication

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MEMS3arication

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MEMS3arication

Microengineering re*ers to the technologies and practice o*

ma-ing three dimensional structures and de1ices )ith

dimensions in the order o* micrometers.

The t)o constructional technologies o* microengineering are 7

Microelectronics9

producing electronic circuitry on silicon chips2

a 1ery )ell de1eloped technology.

Micromachining9

Techni;ues used to produce the structures and mo1ingparts o* microengineered de1ices.

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MEMS3arication

MEMS ma-es use o* the

*arication techni;uesde1eloped *or the integratedcircuit industry to addmechanical elements such as eams2 gears2 diaphragms2 and

springs to de1ices.

6sually *aricated on Siliconsustrates

Source9 Sandia ational Laoratories

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MEMS 3arication

Traditional mechanical means Be.g. machining2 milling2 drilling

etc.C can not e used to shape the MEMS components due totheir e:tremely small si


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Micromachining Techni;ues

Silicon micromachining generally in1ol1es adding layers o*

material o1er a sustrate )ith etching precise patterns in these

layers or the underlying sustrate. The sustrate is typically a silicon )a*er9 a circular dis-2 500 7 "00 m

thic- and %?"? in dia.BJC

3or I+s2 silicon )a*er is an integral part o* the *inished product. 3or MEMS silicon )a*er o*ten acts as a mechanical anchor or support.

Silicon )a*er onding may also e re;uired

Some processes ha1e een de1eloped e:clusi1ely *or Silicon

Micromachining eg. ,niosotropic chemical )et etching

Deep reacti1e ion etching

&a*er onding

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Silicon Micromachining ul- Micromachining9 uilding

microstructure y Aemo1ingmaterials y etching

Enale etter control in Kdirection2 )ith a loss in *le:iility.

Thus2 they are use*ul in highaspect ratio structures.

Sur*ace micromachining9 9 Layer bylayer additionDepositing Thin *ilmsonto the sustrate one layer a*teranother to uild the Ndimensional

geometry. +an produce planar structures Bin

7 directionC )ith littlecontrol in Kdirection

lo) aspect ratio de1ices.

Etched pitEtched Pit

Silicon

Silicon

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ul- Micromachining9

$. ,nisotropic )et etch processes

%. Deep Aeacti1e ion etching

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ul- micromachining

is remo1al o* a lot o* material almost the entire *ilm thic-ness

to create )indo)s2 memranes2 1arious structures

(o) y etching9

&et etching9

isotropicand undercut appears2 )hich can e used in

some de1ices

anisotropic9 structures de*ined y crystal planes

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,nisotropic &et etching

O( not compatile )ith I+s Bal-ali metal such as O

contaminates the transistorsCF high selecti1ity *or 1di**erentcrystal orientation9 B$00 9 $$$ #00 9 $C2 silicon nitride is a 1ery

good mas- Bselecti1ity $000C2 silicon o:ide Bselecti1ity $00C2

stops at pQQ layers

EDP Bethylene diamnie purocatecholC to:ic2 carcinogenic2lo)er anisotropy9 B$00 9 $$$ N5 9 $C

%(# e:plosi1e

TM,( Btetra methyl ammonium hydro:ideC the etch

di**erence not so ig9 B$00 9 $$$ %5 9 $C

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+ontrol o* etch depth

in order to ma-e structures )ith certain dimension2 it is

important to etch the right depthF there are a *e) methods usedto control the etch depth9

Timing it is the least accurate method2 due to the *act that

etching rate 1aries 1ery much )ith temperature2

concentration2 etc,nisotropicetching o* 1groo1es i* only small

rectangularsH)indo)s are made2 then in an anisotropic )et

etch2 the etching stops )hen the t)o planes comine2 ma-ing

a Rgroo1e

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+ontrol o* etch depth

PQQ doping the etch rate is much lo)er in high doped

material2 than in undoped material2 there*ore i* implantationoccurs in the region )here etching should end2 an etch stop is

created .

e:planation9 electrons recomine )ith holes2 limiting the

electrons numer needed *or etching. ot I+compatile2 more process steps2 lo)er

pie


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,nisotrpic ac- etching

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,nisotrpic ac- etching

The pressure sensiti1e diaphragm is *ormed y silicon ac-end

ul- micromachining.

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Silicon Diaphragm

The pressure

sensiti1e diaphragmis *ormed y silicon

ac-end ul-micromachining.

3our pie


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Deep Aeacti1e Ion etching

Dry etching9

e3% 2 no plasma2 rough sur*ace

Plasma etch $9$00

Deep trench etchingBalternating passi1ation step and etching

stepC

o ,d1antage9 1ertical *eatures2

o Disad1antage9 cost o* e;uipment

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ul- MEMS 3arication9 DAIE

start with unpatterned wafer stack a wafer-bonded SOI

(silicon on insulator)

sacrifcial SiO2(1) Pattern photoresistbulk siliconsubstrate

waer-bondedSilicon

photoresist

(2) DRI !ertical etch

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ul- MEMS 3arication9 DAIE

start with unpatterned wafer stack a wafer-bonded SOI

(silicon on insulator)

(") #old e!aporation

($) SiO2isotropic etch

%arrow features released& 'idefeatures ust undercut#old irrors on top and potentiall*sides

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>ul- Silicon? MEMS De1ices

Comb-drive switch photo courtesy

IMT (Neuchate!

Sin"e-a#is tit-mirror photo

courtesy $. Conant% &S'C

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Sur*ace micromachining &hat is it.

a sacri*icial layer eneath another layer is etched Bcompletelyremo1ed *rom the *inal structureC2 thus releasing the upper

layer2 )hich )ill remain connected to the )a*er only in some

regions

It is called Gsur*aceG ecause it ta-es place on the )a*er sur*aceBcompared to ul-2 )here the )hole )a*er thic-ness is etchedC

&hy is it used'

ul- micromachining re;uires igger areas due to anisotropic

)et etching Bthe lateral etch is igC Parts o* the structure can e released and mo1e laterally2 thus it

is use*ul in ma-ing actuators

+an e integrated )ith I+

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Sur*ace Mircomachining

Materials used

lo)stress *ilm polysilicon deposited y LP+RD

it is annealed ecause annealing changes the type o* stress

*rom compressi1e to tensile due to crystalli


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Sura*ace MIcromachining

,pplications9 cantile1er

used to sense chemicals

the cantile1er is heated periodically2 to create 1irations Bdue

to di**erence in thermal coe**icientC

*re;uency o* 1irations is measured and the mass o* chemical

particles can e calculated

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Sur*ace MicromachiningStarting from bare silicon wafer, deposit & patternmultiple layers to form a MEMS wafer

From Cronos/JDSU MUMPS user guide at

www.MEMSRUS.com

Assembly = mechanical manipulation of structures (e.g., raising and latching a vertical mirror plate

!arious techni"ues used, some highly ro rietar

#elease = isotropic chemical etch to remove o$idesSpecial techni"ues may be used to remove li"uid (e.g., critical point drying

%iced and released MEMS device

ompleted MEMS wafer

' ) mas* steps

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1st Optical MEMS device


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e:as ns rumen s g a gProjector

& DLP PROJECTORTM

1 Optical MEMS device

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&a*er onding

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Waer bondin"

is used to join irre1ersile t)o )a*ers together .

onding has to e lea-proo*

typeso* onding9

3usion onding9

*irst the )a*er is immersed in acid to

create hydrophilic sur*aces )ith ( onds

then the sur*aces are put in contact and hydrogen onds are

created2 )ithout pressure

at the end2 a high temperaturetreatment B!00o+C is

gi1en and the onds ecome permanent onds B)ater is

desored and strong Si onds are createdC

sur*aces such as SiHSi2 Si%HSi%2 SiHSiN#2 etc. can e

onded

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,nodic onding in this case temperature ) biasare used to

*orm a strong ond et)een glass and siliconThe t)o )a*ers are placed on a heater and a ias is applied

et)een them Bpositi1e at silicon2 negati1e at the Pyre:Hglass

)a*erC

aQ ions are atracted and ecause they are moile2 theytra1el through the the glass )a*er to the electrode2 oth

)a*ers ecome conducti1e and the electric *ield is

concentrated at the highresistance area at the

inter*aceet)een the )a*ers

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Electrostatic attracti1e *orces pull the )a*ers together

creating a strong contact2 together )ith the temperatureB#00o+C2 creates chemical onds et)een glass and Si

Bo:ygen ions dri*t to the silicon2 creating strong Si ondsC

Sur*aces must e 1ery clean and *lat

ad1antage9 lo)er temperature is needed2 thus this method cane used )ith )a*ers patterned )ith metal2 *or e:ample

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eutectic onding

one Si )a*er has a layer o* gold on top

)hen the t)o )a*ers are put in contact and tempereature

is raised until eutectic temperature2 ,u )ill di**use in Si2

creating a strong alloy at the inter*ace

,pplications o* onding9 creating a sealed ca1ity *or a

capaciti1e pressure sensor2 *or e:ample9

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(istory o* MEMS

U.Some historical stu**U

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The inception o* Microelectromechanical Systems BMEMSC

de1ices occurred in many places and through the ideas andendea1ors o* se1eral indi1iduals. &orld)ide2 ne) MEMS

technologies and applications are eing de1eloped e1ery day.

This unit gi1es a road loo- at some o* the milestones )hich

ha1e contriuted to the de1elopment o* MEMS as )e -no)them today.

jecti1es9

ame three major MEMS technology processes )hich ha1e

emerged in MEMS history.ame at least three major MEMS milestones )hich ha1e

occurred throughout MEMS history.

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$#0Vs

$N Pjunction semiconductor B&. Schott-yC

$# Transistor B8. ardeen2 &.(. rattain2 &. Shoc-leyC

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, transistor uses electrical current or a small

amount o* 1oltage to control a larger changein current or 1oltage.

Transistors are the uilding loc-s o*

computers2 cellular phones2 and all other

modern electronics. In $#2 &illiam Shoc-ley2 8ohn ardeen2

and &alter rattain o* ell Laoratories

uilt the *irst pointcontact transistor.

The *irst transistor used germanium2 asemiconducti1e chemical.

It demonstrated the capaility o* uilding

transistors )ith semiconducti1e materials.

3irst Point +ontact

Transistor and Testing

,pparatus B$#C/Photo +ourtesy o* The

Porticus +entre4

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$50Vs $509 Silicon ,nisotropic Etchants BO(C in ell

La $5#9 Pie


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$5! 3irst integrated circuit

Prior to the in1ention o* the I+ there

)ere limits on the si

on one germanium chip9 $ transistor2

N resistors2 and $ capacitor.

Texas "nstrument#s $irst"nte%rated ircuit

[Photos ourtesy of Texas

"nstruments!

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Shortly a*ter Aoert oyce *rom 3airchild Semiconductor made

the *irst G6nitary +ircuit> on a silicon chip. The *irst patent )as a)arded in $"$ to Aoert oyce.

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$59 >ThereVs Plenty o* Aoom at the


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$59 There s Plenty o* Aoom at the

ottom? Aichard 3eynmanVs >ThereVs Plenty o* Aoom at

the ottom? )as presented at a meeting o* the,merican Physical Society in $5. The tal- populari


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$"0Vs

$"%9 Silicon integrated pie


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$"59 In1ention o* sur*ace

micromachiningF Sur*acemicromachined 3ET

accelerometer B(.+.

athanson2 A.,.

&ic-stromC $"9 ,nisotropic deep

silicon etching B(.,.

&aggener et al.C

)*+, The &esonant ateTransistor Patented

&esonant ate Transistor

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$$ The In1ention o* the


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$$ The In1ention o* the

Microprocessor $$2 Intel pulicly introduced the )orldYs *irst single chip

microprocessor The Intel #00# It po)ered the usicom calculator

This in1ention pa1ed the )ay *or the personal computer

The "ntel .//. Microprocessor

Photo ourtesy of "ntel orporation0usicom calculator

Photo ourtesy of "ntel orporation

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$"0V and 0Vs $"0Ys and $0Vs ul-Etched Silicon &a*ers as Pressure Sensors

GElectrochemically +ontrolled Thinning o* SiliconG y (. ,. &aggenerillustrated anisotropic etching o* silicon Bremo1es silicon selecti1ityC.

This techni;ue is the asis o* the ul- micromachining process.

ul- micromachining etches a)ay the ul- o* the silicon sustrate

lea1ing ehind the desired geometries.

3aricating these micromechanical elements re;uires selecti1e etching

techni;ues such as ul- etching.

In the $0Ys2 a micromachined pressure sensor using a silicon diaphragm

)as de1eloped y Ourt Peterson *rom IM research laoratory.

Thin diaphragm pressure sensors )ere proli*erated in lood pressuremonitoring de1ices .

+onsidered to e one o* the earliest commercial successes o*

microsystems de1ices.

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$0Vs

Se1enties

3irst capaciti1e pressure sensor BStan*ordC

$ Silicon electrostatic accelerometer BStan*ordC

$ Integrated gas chromatograph BS.+. Terry2 8.(. 8erman and

8.. ,ngellC

)*1* (P Micromachined "n23et 4ozzle

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)*1* (P Micromachined "n23et 4ozzle

(e)lett Pac-ard de1eloped the Thermal In-jet Technology

BTI8C. The TI8 rapidly heats in-2 creating tiny ules.

&hen the ules collapse2 the in- s;uirts through an array o*

no


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nozzleslose-up vie5 of a

commercial in23et printer head

illustratin% the nozzles [(e5lettPac2ard!

Schematic of an array of

in23et nozzleslose

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$!0Vs Early $!0Vs2

$!% >Silicon as aMechanical Material? BO.PetersenC

Aeirth o* sur*acemicromachining. Polysiliconstructural layers and o:idesacri*ical layers2U.Ber-eley and &isconsinC

$!% LIW, Process B&. Ehr*eld

et al.C Disposale lood pressure

transducer

$!N Integrated pressuresensor B(oney)ellC

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$!% LIW, Process Introduced

LIW, is a Werman acronym *or ray

lithography Bray LithographieC2Electroplating BWal1ano*ormungC2 and

Molding B,*ormungC.

In the early $!0s Oarlsruhe uclear

Aesearch +enter in Wermany de1elopedLIW,.

It allo)s *or manu*acturing o* high aspect

ratio microstructures.

(igh aspect ratio structures are 1erys-inny and tall.

LIW, structures ha1e precise dimensions

and good sur*ace roughness.

L"A-micromachined

%ear for a mini

electroma%netic

motor[ourtesy of

Sandia 4ational

Laboratories!

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$!0Vs Late $!0Vs

er-eley and ell Las demonstratepolysilicon sur*ace micromechanismF

$!" Silicon )a*er onding BM.ShimoC

The eginning o* MEMS +,D

,nalog De1ices egins accelerometerproject

$!" In1ention o* the ,3M

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$!" In1ention o* the ,3M

In $!" IM de1eloped a microde1ice called the atomic *orce

microscope B,3MC.The ,3M maps the sur*ace o* an atomic structure y

measuring the *orce acting on the tip Bor proeC o* a

microscale cantile1er.

The cantile1er is usually silicon or silicon nitride. It is a 1ery high resolution type o* scanning proe

microscope )ith a resolution o* *ractions o* an ,ngstrom

antilever on an Atomic

$orce Microscope

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$!0Vs Late $!0Vs

er-eley and ell Las demonstratepolysilicon sur*ace micromechanismF

$!" Silicon )a*er onding BM.ShimoC

The eginning o* MEMS +,D

,nalog De1ices egins accelerometerproject

$!! atch *aricated pressure sensors1ia )a*er ondingBo1a SensorC

Aotary electrostatic side dri1e motorsBer-eleyC

Lateral com dri1e BTang2 guyen2(o)e2 er-eleyC

The motors stimulating major interestin Europe2 8apan2 and 6.S

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$0V


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$0VsEarly ineties9

MEMS rapidly e:tending to the )hole )orld. Aesearch on 3arication techni;ues2Design technology2 +,D tools and

De1ices are de1eloping ;uic-ly.

+,D Tools9

MIT2 S. D. Senturia2 MEM+,D$.0

Michigan2 Selden +rary2 +,EMEMS$.0

Techni;ues9

$%9 ul- micromachining BS+AE,M process2 +ornellC

M++ starts the Multi 6ser MEMS Process BM6MPSC2

Sandia SuMMit Technology

osch Process *or DAIE is Patented De1ices9

Wrating light modulator in1ented at Stan*ord 6ni1ersity BSolgaard2Sandejas2 loomC

3irst micromachined hinge

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)**6 L h M d l


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)**6 ratin% Li%ht Modulator

The de*ormale grating light

modulator BWLMC )as introducedy Solgaardin $%.

It is a Micro ptoElectro

Mechanical System BMEMSC.

It has een de1eloped *or uses in1arious applications9 Display

technology2 graphic printing2

lithography and optical

communications

ratin% Li%ht 7alve

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)**8 Multi-9ser MEMS Processes


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)**8 Multi 9ser MEMS Processes

:M9MPs; Emer%es In $N Microelectronics +enter o* orth +arolina BM++C

created M6MPs9, *oundry meant to ma-e microsystems processing highly

accessile and cost e**ecti1e *or a large 1ariety o* users

, three layer polysilicon sur*ace micromachining process

3or a nominal cost2 M6MPs participants are gi1en a $ cm%area to create their o)n design.

In $!2 Sandia ational Las de1eloped S6MMiT IR BSandia

6ltraplanar2 Multile1el MEMS Technology 5C

This process later e1ol1ed into the S6MMiT R2 a *i1elayer

polycrystalline silicon sur*ace micromachining process

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T5o simple structures usin% the M9MPsprocess [M4!

A MEMS device built usin% S9MMiT "7

[Sandia 4ational Laboratories!

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Mid. $0Vs

De1ices

$N9 Digital mirror display BTe:asInstrumentsC

ioMEMS rapidly de1elopment

$#9+ommercial sur*ace micromachined

accelerometer B,DL50CB,nalog De1icesC MEMS Design

MEM+,D%.0

Microcosm Inc. *or MEM+,D

Intellisense Inc. *or IntelliSuite

ISE *or T+,D2 SLIDIS and I+M,T

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)**8 $i M f dA l


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)**8 $irst ManufacturedAccelerometer

In $N ,nalog De1ices )ere the *irst to produce a sur*ace

micromachined accelerometer in high 1olume.The automoti1e industry used this accelerometer in

automoiles *or airag deployment sensing.

It )as sold *or X5 Bpre1iously2 TA& macro sensors )ere

eing sold *or aout X%0C. It )as highly reliale2 1ery small2 and 1ery ine:pensi1e.

It )as sold in record rea-ing numers )hich increased the

a1ailaility o* airags in automoiles.

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p %

Patented In $#2 osch2 a company *rom

Wermany2 de1eloped the DeepAeacti1eIon Etching BDAIEC

process.

DAIE is a highly anisotropic etch

process used to create deep2 steepsided holes and trenches in )a*ers.

It )as de1eloped *or micro de1ices

)hich re;uired these *eatures.

It is also used to e:ca1ate trenches*or highdensity capacitors *or

DA,M BDynamic randomaccess

memoryC.

Trenches etched 5ith


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Later $0Vs

De1ices

ioMEMS9 Micro*luidics starts)ith capillary electrophoresis.

T,S BMicrototalanalysis

SystemC 1ision *or diagnosis2

sensing and synthesis

ptical MEMS ooming and ust*rom $!%00% BLucentC

$ ptical net)or- s)itch

BLucentC

A3 MEMS *rom %000 +ommerciali Early 6///#s ?ptics


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> y p

In $ Lucent Technologies de1eloped the *irst optical net)or-

s)itch. ptical s)itches are optoelectric de1ices.

They consist o* a light source and a detector that produces a

s)itched output.

The s)itch pro1ides a s)itching *unction in a datacommunications net)or-.

These MEMS optical s)itches utili Early 6///#s 0ioMEMS


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> y

Scientists are comining sensors and actuators )ith emerging

iotechnology. ,pplications include

drug deli1ery systems

insulin pumps :see picture;

D, arrays

laonachip BL+C

Wlucometers

neural proe arrays

micro*luidics"nsulin pump [ S5itzerland!

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+,, ,-ustica introduces )orldYs *irst digital microphone

the ,O6%000

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%000 till t d


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%000till today

MEMS Microphone %005

%0$59 Dissol1ale Micro Medical De1ices

$$H$!H$5 Thin-ing ac- to the late $"0s )hen scienti*ic

researchers )ere en1isioning using a tue made out o* metal

BstentC to open up an artery2 they )ould ne1er ha1e imagined )e

are on the 1erge o* stents that dissol1e in the ody o1er timeJ

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Massi1e industrialisation and commercialisation.

%00$ Tria:is accelerometers appear on the mar-et.

%00% 3irst nanoimprinting tools announced.

%00N MEMS microphones *or 1olume applications introduced.

%00N Discera start sampling MEMS oscillators.

%00# TIVs DLP chip sales rose to nearly X00 million.

%005 ,nalog De1ices shipped its t)o hundred millionth MEMS

ased inertial sensor.

%00" Pac-aged tria:is accelerometers smaller then $0 mmN are

ecoming a1ailale.

%00" Dual a:is MEMS gyros appear on the mar-et.

%00" Perpetuum releases 1iration energy har1ester.

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A3 MEMS

A3 s)itch2

PTI+,L MEMS

Micromirror array *or optical s)itching2

IMEMS

La on a chip2 +apillary Electrophoresis ,nalysis

MiniMed ParadigmZ 5%% insulin pump

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Aetina array9

[ourtesy of Sandia 4ational Laboratories!

Micropump *or insulin

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MiniMed ParadigmZ 5%% insulin pump

The MiniMedParadigm522 insulinpump, with sensor, transmitter and

infusion line is one of a few devies on

the mar!et that an not only monitor a

person"s #luose levels 2$%&, but andeliver insulin on an as needed basis. ts

omponents are

B,C an e:ternal pump and computer2

BC a so*t cannulathat deli1ers the insulin2

B+C an interstitial glucose sensor2 and

BDC a )ireless radio de1ice that

communicates )ith the

Micropump *or insulin

[Printed 5ith permission

from


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computer.The sensor B+C is placed under

the s-in. The sensor continuouslymeasures glucose le1els in the interstitial

*luid Bthe *luid et)een ody tissuesC.

The measurements *rom the sensor are

recei1ed in real time y the )irelessradio de1ice BDC. This de1ice sends the

readings to the computer B,C )hich

determines the amount o* insulin

needed. The pump B,C administers that

amount into the patient 1ia the cannulaBC. The MiniMed Paradigm Z

computer also stores all the data.

MiniMed Paradigm Z 5%%

insulin pump2 )ithMiniLin-TM4 transmitter

and in*usion set. /Printed

)ith permission *rom

Medtronic Diaetes4

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, therapeutic ioMEMS de1ice

currently eing tested is the arti*icialretinal prosthesis called the ,rgus[

Aetinal Prosthesis System.

Artifiial Retina(he heart of the

system is an artifiial retina )aneletrode array plaed diretly on the

retina at the ba! of the eye. (his

array dupliates the tas! of the

photoreeptor ells in the retina.

(hese ells are destroyed in retinal

diseases suh as a#e)related maular

de#eneration and retinitis

pi#mentosa*R+.

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The Aapid2 ,utomated Pointo*+are System

BAapi

saliva> urine; so that patient ailments can be

uic2ly dia%nosed and treated@ Aapi


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Summary

Since the in1ention o* the transistor2 scientists ha1e een trying

to impro1e and de1elop ne) micro electro mechanical systems. The *irst MEMS de1ices measured such things as pressure in

engines and motion in cars. Today2 MEMS are controlling our

communications net)or-s

MEMS are sa1ing li1es y in*lating automoile air ags andeating hearts.

MEMS are tra1eling through the human ody to monitor lood

pressure.

MEMS are e1en getting smaller. &e no) ha1e nano electromechanical systems BEMSC.

The applications and gro)th *or MEMS and EMS are endless

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+hallenges o* MEMS

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+hallenges o* MEMS


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+hallenges o* MEMS

The comple:ity o* MEMS design.

Typical MEMS de1ices2 e1en simple ones2 manipulateenergy Bin*ormationC in se1eral energy domains. The

designer must understand2 and *ind )ays to control2 comple:

interactions et)een these domains.

Parallel processingdoes not lend it sel* to stepy step optimi


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+hallenges

Pac-aging

usually need to interact )ith the en1ironment in some )ayBe.g.2 pressure sensor2 chemical sensorC

1ery di1ersi*ied 7 no standard pac-aging method

Testing9

in1ol1es multiple energy domains

Po)er sources

+,D tools Binterdisciplinary2 usually in1ol1es se1eral energy

domains2 mechanical2 electrical2 thermal2 etc.C

MultidisciplinaryHinterdisciplinary collaoration

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MEMS Standards B'C


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MEMS Standards B'C

Standards are generally dri1en y the needs o* high1olume

applications. MEMS has roots in integrated circuit industry

ut2 the t)o mar-et dynamics di**er.

The major di**erence is the lac- o* standards in MEMS.

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The Multidiscipline nature o*

MEMS technology

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Natura Science1

/hysics 0 Chemistry


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Mechanica n"ineerin"

Machine components desi"n.

/recision machine desi"n.

Mechanisms 0 inka"es.

Thermomechanicas1

soid 0 uid mechanics% heattranser% racture mechanics.

Intei"ent contro.

Micro process e*uipment

desi"n and manuacturin".

/acka"in" and assemby desi"n.

2uantum physics

Soid-state physics% Scain" aws

ectrica n"ineerin"

/ower suppy.

ectric systems

desi"n in eectro-

hydrodynamics.

Si"na transduction%ac*uisition% condition-

in" and processin".

ectric 0 inte"rated

circuit desi"n.

ectrostatic 0 MI.

Materias n"ineerin"

Materias or device

components 0 packa"in".

Materias or si"na

transduction.Materias or abrication

processes.

/rocess n"ineerin"

3esi"n 0 contro o

micro abrication processes.

Thin im technoo"y.

Industria n"ineerin"

/rocess impementation.

/roduction contro.

Micro packa"in" 0 assemby.

ectromechanica

-chemica /rocesses

Materia

Science

BMultidiscipline o* MEMS.Slide presentationC(S6

/hysics 0 Chemistry

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MEMS ,pplications

,utomoti1e industry

Medical

Digital Light Projection Technology

Printing Technology

SM,AT PhoneU

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MEMS ,pplications


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MEMS ,pplications

Where can you ind

MMS4

in your carU

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,pplications in ,utomoti1e Industry


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>E1ery ne) car sold has micromachined sensors onoard. Theyrange *rom

M,P BMani*old ,solute PressureC engine sensors2

,ccelerometers *or acti1e suspension systems2

,utomatic door loc-s2 and antiloc- ra-ing and airagsystems.

http+www.analog.comlibrarytechArticlesmems$lbc*gdr-.html

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Microaccelerometer

,DL509 sur*ace micromachined2integrated i+MS B,nalog De1ices2 $5C

'nao" 3evices

Analog %evices A%/01) accelerometerSurface micromachining capacitive sensor 2.1 $ 2.1 mm die incl. electronic controls

ost+ 34) vs '34)) bul* sensor (564 ut to 31a$is by 667 #eplaced by 48a$is A%/01)

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,cceleration Sensors


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,cceleration Sensors

apacitive Accelerometer

Silicon substrate

Elastic hinge Proo Mass

Spacer !orce

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Micro inertia sensor (acceerometer!

"#nalog Devices$ %nc


Inertia Sensor *or >,ir ag? Deployment System

ME 505Pressure Sensors


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apacitive 9ressure Sensor

Silicon substrate

9int

9e$t

Spacer

Me'brane

!orce

Measure# time

:ovaSensor;s pie


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,pplications Medical

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,pplicationsMedical


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pp Micropump

Lo)er % )a*ers onded 1ia silicon *usion onding. Top)a*er later glued.

Pie


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pp

&ioMMS1

ME 505,pplicationsDigital Light Projection

T h l


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Technology

DMD( 1stOptical MEMS device

Te#as Instruments

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TMDigital Light Projector


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& DLP PROJECTOR

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,pplicationsPrinting Technology


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pp g gy

In-jet Printers

U +omputer readH)rite heads

Magnetic dis- readH)rite head

In- jet print head

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,pplications9+ommunications


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pp

Micro S)itches *or 3ier ptical et)or-

BLucent Technology2 Murray (ill2 8C

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,pplications9+ommunications


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pp

MEMS ptical S)itch Lucent micro

mirror $"$" ,rray

Si


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MEMS Aesonators2 *ilters2 Phase shi*ters2 Aecon*igurale

antennae

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+onsumer Electronics


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Smart Phones2 +ameras

Micromachinedaccelerometer sensors areno) eing used in seismicrecording2 machinemonitoring2 and diagnostic

systems or asically anyapplication )here gra1ity2shoc-2 and 1iration are*actors.?

The *ield is also )ideningconsideraly in othermar-ets.

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MEMS Mar-et


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7 8 biion at the componenteve nabe 7 9,, biions

market:

Akustika: MEMS-based speakers

(Audiopixels)

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MEMS Mar-et


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,utomoti1e industry9

mani*old air pressure sensor B(oney)ell2 MotorolaC nearly #0 millionunits per year.

,ir ag sensor Baccelerometer950 million units per yearC.

,nolog De1ices9 ,ccelerometer2 Wyroscopes.

Medical

Disposale lood pressure sensors at %0 million units per year. Digital Light Projection Technology9

TI digital mirror display BDMDC 1ideo projection system Bde1elopmentcost ] X$C

Printing Technology9 In-jet no


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+,D 3or MEMS

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MEMS Design Tools


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E:ample9 Pressure Sensor Design

The design in1ol1es9 Designing the pressure sensor memrane geometry9

ma:imi


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in MEMSPA

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Meshed Model


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Meshed in (ypermesh 5.0

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The de*lection analysis


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In micron

Ma:imum De*lection9N.5 micron

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Stress analysis


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Ma:imum Stress9 #%# MPa

In MPa

ME 505The Schematic o* Pie


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sensor

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Roltage Sensiti1ity Simulation


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TP Ten Products


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,s *or areas o* opportunity2 RD+Ys mar-et attracti1eness inde:

identi*ies the top $0 near term opportunities in the MEMS H MSTmar-et9 Micro*luidic iochips *or medical diagnostics and drug disco1ery

Wlucose micro*luidic monitoring sensors

Tire pressure sensors

(ard dis- dri1e heads +onsumer print heads *or in-jet printers

1er the counter micro*luidic testing de1ices *or detecting medicalconditions

Large *ormat print heads

De1ices that enale ad1anced automoti1e *unctions

,S accelerometers and gyroscopes

,utomoile mass air*lo) sensors

Microphones

A3 antennas

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The Pressure Sensor


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3ig.5. TP RIE& 9 Silicon Memrane )a*er

onding pads+onductor

Pattern

Pie


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These are ased on the de*lection o* Silicon Memrane.

The sensing is o* t)o types

+apaciti1e

Pie


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ul- micro machining in single crystal silicon and

Sur*ace micromachining in polysilicon.

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Pressure Sensor Aange


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1acuum2

Lo) pressure B0.0% to 0.$ ,tmC2 Medium pressure B0.%5 to $0 ,tmC2

(igh pressure B"0 to more than 500 ,tmC.

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+apaciti1e pressure sensors


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high sensiti1ity

small dynamic rangeecause the gap et)een the capacitor plates must e 1ery

small to otain a large capacitance.

, thin silicon diaphragm is employed )ith a narro) capaciti1e

gap and a 1acuum ca1ity *or re*erence pressure. The silicon diaphragms ha1e etter mechanical properties2

including *reedom *rom creep2 resulting in etter repeataility

than metal diaphragms.

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The sensor is *ormed *rom t)o glass sustrates and a silicon

)a*er. The silicon )a*er is sand)iched et)een the t)o glass )a*ers

y anodic onding2 simultaneously *orming a sealed re*erence

ca1ity.

,n alloy o* KnR3e is used as a on E1aporale Wetter BEWCto maintain the re*erence ca1ity at high 1acuum. ,*ter onding

in 1acuum2 the EW can asor the remaining gas in the

re*erence ca1ity.

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6se o* a PQQ Bhea1ily doped oronC etch stop layer pro1ides

accurate control o* diaphragm thic-ness.

Structure o* a capaciti1e asolute pressure sensor

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Pressure range 0$00mTorr

+an e e:tended to aout 500 mtorr.

1. A Ultra-Sensitive, High-Vacuum Absolute Capacitive Pressure Sensor;Technical Digest of the 14th IEEE International Conference On Micro ElectroMechanical Systems (MEMS 2001) !!" 1##$1#% Interla&en S'iterlan*an" 21$2+ 2001"

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&or-ing o* pie


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The sensing material

diaphragm *ormed on a silicon sustrate2

)hich ends )ith applied pressure. The

memrane de*ection is typically less than $

^m.

, de*ormation occurs in the crystal lattice o* the

diaphragm ecause o* that ending.

This de*ormation causes a change in the

resisti1ity o* the material. This change can e

an increase or a decrease according to the

orientation o* the resistors.

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&or-ing o* pie


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The Pie


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Mature processing technology.

Di**erent pressure le1els can e achie1ed according to the

application.

,lso2 1arious sensiti1ities can e otained.

Aeadout circuitry can e either onchip or discrete

Lo)cost

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Diaphragm


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The pressure sensiti1e diaphragm is *ormedy silicon ac-end ul- micromachining.

Silicon diaphragms are *ormed y,nisotropically etching the ac- o* asilicon )a*er. 6sually a s;uare memranecan e *ormed y )et etching in O( orTM,( BTriMethyl ,mmonium (ydroideCsolution.

The circular memranes can e otained ydry etch process.

The silicon diaphragms 550 microns _$

micron and area $ $00 s;uare mm. The sihe SEM (ScanningElectron Microscopeview of the bac*8side ofone of the sensor

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Typical Pie


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The pie


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The resistors are placed on the

diaphragm such that t)o e:periencemechanical tension in parallel and theother t)o are perpendicular to thedirection o* current *lo).

Thus2 the t)o pairs e:hiit resistance

changes opposite to each other. Thesepairs are located diagonally in the ridgesuch that applied pressure produces a

ridge imalance.

De*ormation y applied pressure causes

high le1els o* mechanical tension at theedges o* the diaphragm. Positioning theresistors in this area o* highest tensionincreases sensiti1ity.

The pressure

sensor chip

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,lumina sustrates are used *or the pac-aging o* the sensor

ere the sensor is bonded on the

substrate .>he wire bonding isalso done.

>he alumina substrate has a hole atthe middle. >his is re"uired fordifferential pressure measurementsand the air pressure is always appliedto the bac* side of the sensor via this

hole

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The pac-ed pressure sensor


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, cap is made *or the input pressure port. The electrical

connections are co1ered )ith epo:y *or electrical isolation.

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MEMS in ,+TIS

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MEMS in ,ction


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MEMS in ,ction


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MEMS in ,ction


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MEM WA


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MEMS Directional Microphone


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Summary

h l


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&e ha1e learnt9

&hat is MEMS )hy do )e need mems 2 ho) do )e*aricate2 )hat are the challenges in design2 *arication2

pac-aging and testing MEMS

&e ha1e re1ie)ed current MEMS mar-et and a *e)

applications

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Documents

Overview of MEMS