《信息科學(xué)類專業(yè)英語》課件第24章

Lesson24AnIntroductiontoMEMS(Micro-electromechanicalSystems)

(第二十四課微機(jī)電系統(tǒng)簡介)

Vocabulary(詞匯)ImportantSentences(重點句)QuestionsandAnswers(問答)Problems(問題)

MEMShasbeenidentifiedasoneofthemostpromisingtechnologiesforthe21stCenturyandhasthepotentialtorevolutionizebothindustrialandconsumerproductsbycombiningsilicon-basedmicroelectronicswithmicromachiningtechnology.Itstechniquesandmicrosystem-baseddeviceshavethepotentialtodramaticallyaffectofallofourlivesandthewaywelive.

ThisreportpresentsageneralintroductiontothefieldofMEMS,withemphasisonitscommercialapplicationsanddevicefabricationmethods.ItalsodescribestherangeofMEMSsensorsandactuators,thephenomenathatcanbesensedoracteduponwithMEMSdevices,andoutlinesthemajorchallengesfacingtheindustry.1WhatisMEMS?

Micro-electromechanicalsystems(MEMS)isaprocesstechnologyusedtocreatetinyintegrateddevicesorsystemsthatcombinemechanicalandelectricalcomponents.TheyarefabricatedusingIntegratedCircuit(IC)batchprocessingtechniquesandcanrangeinsizefromafewmicrometerstomillimetres.Thesedevices(orsystems)havetheabilitytosense,controlandactuateonthemicroscale,andgenerateeffectsonthemacroscale.

MEMS,anacronymthatoriginatedintheUnitedStates,isalsoreferredtoasMicrosystemsTechnology(MST)inEuropeandMicromachinesinJapan.Regardlessofterminology,theunitingfactorofaMEMSdeviceisinthewayitismade.Whilethedeviceelectronicsarefabricatedusing“computerchip”ICtechnology,themicromechanicalcomponentsarefabricatedbysophisticatedmanipulationsofsiliconandothersubstratesusingmicromachiningprocesses.Processessuchasbulkandsurfacemicromachining,aswellasHigh-Aspect-RatioMicromachining(HARM)selectivelyremovepartsofthesiliconoraddadditionalstructurallayerstoformthemechanicalandelectromechanicalcomponents.[1]Whileintegratedcircuitsaredesignedtoexploittheelectricalpropertiesofsilicon,MEMStakesadvantageofeithersilicon’smechanicalpropertiesorbothitselectricalandmechanicalproperties.

Inthemostgeneralform,MEMSconsistofmechanicalmicrostructures,microsensors,microactuatorsandmicroelectronics,allintegratedontothesamesiliconchip.ThisisshownschematicallyinFig.1.Fig.1SchematicillustrationofMEMScomponents.

Microsensorsdetectchangesinthesystem’senvironmentbymeasuringmechanical,thermal,magnetic,chemicalorelectromagneticinformationorphenomena.Microelectronicsprocessthisinformationandsignalthemicroactuatorstoreactandcreatesomeformofchangestotheenvironment.

MEMSdevicesareverysmall;theircomponentsareusuallymicroscopic.Levers,gears,pistons,aswellasmotorsandevensteamengineshaveallbeenfabricatedbyMEMS(Fig.2).However,MEMSisnotjustabouttheminiaturizationofmechanicalcomponentsormakingthingsoutofsilicon(infact,thetermMEMSisactuallymisleadingasmanymicromachineddevicesarenotmechanicalinanysense).MEMSisamanufacturingtechnology;aparadigmfordesigningandcreatingcomplexmechanicaldevicesandsystemsaswellastheirintegratedelectronicsusingbatchfabricationtechniques.[2]Fig.2(a)AMEMSsiliconmotortogetherwithastrandofhumanhair,and(b)thelegsofaspidermitestandingongearsfromamicro-engine[2-SandiaNationalLabs,SUMMiT*Technology,].

Fromaveryearlyvisionintheearly1950’s,MEMShasgraduallymadeitswayoutofresearchlaboratoriesandintoeverydayproducts.Inthemid-1990’s,MEMScomponentsbeganappearinginnumerouscommercialproductsandapplicationsincludingaccelerometersusedtocontrolairbagdeploymentinvehicles,pressuresensorsformedicalapplications,andinkjetprinterheads.Today,MEMSdevicesarealsofoundinprojectiondisplaysandformicropositionersindatastoragesystems.However,thegreatestpotentialforMEMSdevicesliesinnewapplicationswithintelecommunications(opticalandwireless),biomedicalandprocesscontrolareas.

MEMShasseveraldistinctadvantagesasamanufacturingtechnology.Inthefirstplace,theinterdisciplinarynatureofMEMStechnologyanditsmicromachiningtechniques,aswellasitsdiversityofapplicationshasresultedinanunprecedentedrangeofdevicesandsynergiesacrosspreviouslyunrelatedfields(forexamplebiologyandmicroelectronics).Secondly,MEMSwithitsbatchfabricationtechniquesenablescomponentsanddevicestobemanufacturedwithincreasedperformanceandreliability,combinedwiththeobviousadvantagesofreducedphysicalsize,volume,weightandcost.Thirdly,MEMSprovidesthebasisforthemanufactureofproductsthatcannotbemadebyothermethods.ThesefactorsmakeMEMSpotentiallyafarmorepervasivetechnologythanintegratedcircuitmicrochips.However,therearemanychallengesandtechnologicalobstaclesassociatedwithminiaturizationthatneedtobeaddressedandovercomebeforeMEMScanrealizeitsoverwhelmingpotential.2DefinitionsandClassifications

ThissectiondefinessomeofthekeyterminologyandclassificationsassociatedwithMEMS.Itisintendedtohelpthereaderandnewcomerstothefieldofmicromachiningbecomefamiliarwithsomeofthemorecommonterms.AmoredetailedglossaryoftermshasbeenincludedinAppendixA.

Fig.3illustratestheclassificationsofmicrosystemstechnology(MST).AlthoughMEMSisalsoreferredtoasMST,strictlyspeaking,MEMSisaprocesstechnologyusedtocreatethesetinymechanicaldevicesorsystems,andasaresult,itisasubsetofMST.Fig.3Classificationsofmicrosystemstechnology.

Micro-optoelectromechanicalsystems(MOEMS)isalsoasubsetofMSTandtogetherwithMEMSformsthespecializedtechnologyfieldsusingminiaturizedcombinationsofoptics,electronicsandmechanics.[3]Boththeirmicrosystemsincorporatetheuseofmicroelectronicsbatchprocessingtechniquesfortheirdesignandfabrication.ThereareconsiderableoverlapsbetweenfieldsintermsoftheirintegratingtechnologyandtheirapplicationsandhenceitisextremelydifficulttocategoriseMEMSdevicesintermsofsensingdomainand/ortheirsubsetofMST.TherealdifferencebetweenMEMSandMSTisthatMEMStendstousesemiconductorprocessestocreateamechanicalpart.Incontrast,thedepositionofamaterialonsiliconforexample,doesnotconstituteMEMSbutisanapplicationofMST.3Transducer

Atransducerisadevicethattransformsoneformofsignalorenergyintoanotherform.ThetermtransducercanthereforebeusedtoincludebothsensorsandactuatorsandisthemostgenericandwidelyusedterminMEMS.

(1)?SensorAsensorisadevicethatmeasuresinformationfromasurroundingenvironmentandprovidesanelectricaloutputsignalinresponsetotheparameteritmeasured.Overtheyears,thisinformation(orphenomenon)hasbeencategorizedintermsofthetypeofenergydomainsbutMEMSdevicesgenerallyoverlapseveraldomainsordonotevenbelonginanyonecategory.Theseenergydomainsinclude:

Mechanical—force,pressure,velocity,acceleration,position.

Thermal—temperature,entropy,heat,heatflow.

Chemical—concentration,composition,reactionrate.

Radiant—electromagneticwaveintensity,phase,wavelength,polarizationreflectance,refractiveindex,transmittance.

Magnetic—fieldintensity,fluxdensity,magneticmoment,permeability.

Electrical—voltage,current,charge,resistance,capacitance,polarization.

(2)?ActuatorAnactuatorisadevicethatconvertsanelectricalsignalintoanaction.Itcancreateaforcetomanipulateitself,othermechanicaldevices,orthesurroundingenvironmenttoperformsomeusefulfunction.4Applications

Today,highvolumeMEMScanbefoundinadiversityofapplicationsacrossmultiplemarkets(Table1).Table1ApplicationsofMEMS

AsanemergingtechnologyMEMSproductsarecentredaroundtechnology-productparadigmsratherthanproduct-marketparadigms.Consequently,aMEMSdevicemayfindnumerousapplicationsacrossadiversityofindustries.Forexample,theMEMSinkjetprinterheadnozzleinwidespreadusetodayhasdevelopedfromanozzleoriginallyusedinnuclearseparation.ThecommercialisationofselectedMEMSdevicesisillustratedinTable2.Table2CommercialisationofselectedMEMSdevices.

Itisnotwithinthescopeofthisreporttodetailallthecurrentandpotentialapplicationswithineachmarketsegment.Instead,aselectionofthemostestablishedMEMSdevicesisdetailedalongwiththemostpotentiallysignificantfutureapplications.5TheFutureofMEMS

SomeofthemajorchallengesfacingtheMEMSindustryinclude:

AccesstoFoundries.MEMScompaniestodayhaveverylimitedaccesstoMEMSfabricationfacilities,orfoundries,forprototypeanddevicemanufacture.Inaddition,themajorityoftheorganizationsexpectedtobenefitfromthistechnologycurrentlydonothavetherequiredcapabilitiesandcompetenciestosupportMEMSfabrication.Forexample,telecommunicationcompaniesdonotcurrentlymaintainmicromachiningfacilitiesforthefabricationofopticalswitches.AffordableandreceptiveaccesstoMEMSfabricationfacilitiesiscrucialforthecommercialisationofMEMS.

Design,SimulationandModeling.DuetothehighlyintegratedandinterdisciplinarynatureofMEMS,itisdifficulttoseparatedevicedesignfromthecomplexitiesoffabrication.Consequently,ahighlevelofmanufacturingandfabricationknowledgeisnecessarytodesignaMEMSdevice.Furthermore,considerabletimeandexpenseisspentduringthisdevelopmentandsubsequentprototypestage.Inordertoincreaseinnovationandcreativity,andreduceunnecessary“time-to-market”costs,aninterfaceshouldbecreatedtoseparatedesignandfabrication.[4]Assuccessfuldevicedevelopmentalsonecessitatesmodelingandsimulation,itisimportantthatMEMSdesignershaveaccesstoadequateanalyticaltools.Currently,MEMSdevicesuseolderdesigntoolsandarefabricatedona“trialanderror”basis.Therefore,morepowerfulandadvancedsimulationandmodelingtoolsarenecessaryforaccuratepredictionofMEMSdevicebehaviour.

PackagingandTesting.ThepackagingandtestingofdevicesisprobablythegreatestchallengefacingtheMEMSindustry.Aspreviouslydescribed,MEMSpackagingpresentsuniqueproblemscomparedtotraditionalICpackaginginthataMEMSpackagetypicallymustprovideprotectionfromanoperatingenvironmentaswellasenableaccesstoit.Currently,thereisnogenericMEMSpackagingsolution,witheachdevicerequiringaspecializedformat.Consequently,packagingisthemostexpensivefabricationstepandoftenmakesup90%(ormore)ofthefinalcostofaMEMSdevice.

Standardization.DuetotherelativelylownumberofcommercialMEMSdevicesandthepaceatwhichthecurrenttechnologyisdeveloping,standardizationhasbeenverydifficult.Todate,highqualitycontrolandbasicformsofstandardizationaregenerallyonlyfoundatmulti-milliondollar(orbilliondollars)investmentfacilities.However,in2000,progressinindustrycommunicationandknowledgesharingwasmadethroughtheformationofaMEMStradeorganization.BasedinPittsburgh,USA,theMEMSIndustryGroup(MEMS-IG)withfoundingmembersincludingXerox,Corning,Honeywell,IntelandJDSUniphase,grewoutofstudyteamssponsoredbyDARPAthatidentifiedaneedfortechnologyroadmappingandasourceforobjectivestatisticsabouttheMEMSindustry.Inaddition,aMEMSindustryroadmap,sponsoredbytheSemiconductorEquipmentandMaterialsInternationalorganization(SEMI),hasalsobeenidentifiedtosharepre-competitiveinformationontheprocesses,technology,applicationandmarketsforMEMS.[5]Thisweb-basedorganizationcanbefoundathttp://www.roadmap.nl.

SeveralotherEuropeaninitiativessupportedbygovernmentsandtheEuropeancommissionhavebeencoordinated:Europractice(MicrosystemsServiceforEurope),NEXUS(NetworkofExcellenceinMultifunctionalMicrosystems),aimedatenhancingEuropeanindustrialcompetitivenessintheglobalmarketplace,andNetpack,whoseroleistodrivethedevelopmentanduseofadvancedpackagingandintegrationtechnologies.ThenetworkingofthesesmallercompaniesandorganizationsonbothaEuropeanandaglobalscaleisextremelyimportantandnecessarytolaythefoundationforaformalstandardizationsystem.

EducationandTraining.ThecomplexityandinterdisciplinarynatureofMEMSrequireeducatedandwell-trainedscientistsandengineersfromadiversityoffieldsandbackgrounds.ThecurrentnumbersofqualifiedMEMS-specificpersonnelisrelativelysmallandcertainlylowerthanpresentindustrydemand.EducationatgraduatelevelisusuallynecessaryandalthoughthenumberofuniversitiesofferingMEMS-baseddegreesisincreasing,gainingknowledgeisanexpensiveandtime-consumingprocess.[6]Therefore,inordertomatchtheprojectedneedfortheseMEMSscientistsandengineers,anefficientandlowercosteducationmethodologyisnecessary.Oneapproach,forexample,isindustry-led(ordriven)academicresearchcentresofferingtechnology-specificprogrammeswithcommercialintegration,trainingandtechnologytransfer.

1.?fabricatevt.[美]制作,建造,裝配；捏造,虛構(gòu),偽造(謊言,借口,文件,簽名等)；創(chuàng)立(理論等)。

2.?acronymn.只取首字母的縮寫詞。

3.?substraten.(=substratum)底層,地層;【無】(半導(dǎo)體工藝中的)襯[基]底;基片;墊托物;感光膠層;【生態(tài)】基層;【生化】基質(zhì);被酶作用物;真晶格。

4.?electromechanicaladj.[機(jī)]電動機(jī)械的,機(jī)電的,電機(jī)的。Vocabulary

5.?micropositionern.微型遠(yuǎn)程位置調(diào)節(jié)器，微動臺。

6.?interdisciplinaryadj.各學(xué)科間的,跨學(xué)科的。

7.?unprecedentedadj.空前的;史無前例的;無比的；新奇的;嶄新的。

8.?synergyn.(=synergism)協(xié)同,配合,企業(yè)合并后的協(xié)力優(yōu)勢或協(xié)合作用。

9.?overlapvt.與……交搭;疊蓋??；(與……)部分相一致(巧合)n.重復(fù),部分一致;交搭;復(fù)疊部分,交搭處;覆蓋物;涂蓋層;【植】蓋覆;【攝】重疊攝影;【數(shù)】交疊,相交;復(fù)合。

10.?categorisev.加以分類。

11.?radiantadj.輻[放,發(fā)]射的,發(fā)生輻射熱的;發(fā)光的;光芒四射的,燦爛的;容光煥發(fā)的。

12.?commercializationn.商業(yè)化。

13.?roadmapn.路標(biāo)。

14.?competitiveadj.競爭的，競賽的；與……不相上下的；經(jīng)得起競爭的。

15.?time-consuming費時的；消耗時間的。

[1]Processessuchasbulkandsurfacemicromachining,aswellasHigh-Aspect-RatioMicromachining(HARM)selectivelyremovepartsofthesiliconoraddadditionalstructurallayerstoformthemechanicalandelectromechanicalcomponents.

采用像堆積和表面顯微機(jī)械加工工藝，以及高長寬比的顯微機(jī)械加工(HARM)可選擇移動或增加硅晶體部件附加的結(jié)構(gòu)層來形成機(jī)械的和電動機(jī)械的部件。ImportantSentences

[2]MEMSisamanufacturingtechnology;aparadigmfordesigningandcreatingcomplexmechanicaldevicesandsystemsaswellastheirintegratedelectronicsusingbatchfabricationtechniques.

MEMS是一種制造工藝；一種設(shè)計和生產(chǎn)復(fù)雜的設(shè)備和系統(tǒng)的模式，同時可以通過批量制作技術(shù)集成電子器件。

[3]Micro-optoelectromechanicalsystems(MOEMS)isalsoasubsetofMSTandtogetherwithMEMSformsthespecializedtechnologyfieldsusingminiaturizedcombinationsofoptics,electronicsandmechanics.

微光電動機(jī)械系統(tǒng)(MOEMS)是MST的一個子集和MEMS技術(shù)融合所形成的光、電和機(jī)械小型化的專門技術(shù)領(lǐng)域。

[4]Inordertoincreaseinnovationandcreativity,andreduceunnecessary‘time-to-market’costs,aninterfaceshouldbecreatedtoseparatedesignandfabrication.

為了增加改革和創(chuàng)新，以及減少不必要的面市時間代價，應(yīng)該劃分一個分離設(shè)計和生產(chǎn)的界線。

[5]Inaddition,aMEMSindustryroadmap,sponsoredbytheSemiconductorEquipmentandMaterialsInternationalorganization(SEMI),hasalsobeenidentifiedtosharepre-competitiveinformationontheprocesses,technology,applicationandmarketsforMEMS.

另外，一個MEMS工業(yè)路標(biāo)組織，由半導(dǎo)體設(shè)備與材料國際組織(SEMI)贊助，已經(jīng)確定共享MEMS在工藝、技術(shù)、應(yīng)用和市場方面面臨競爭的信息。

[6]EducationatgraduatelevelisusuallynecessaryandalthoughthenumberofuniversitiesofferingMEMS-baseddegreesisincreasing,gainingknowledgeisanexpensiveandtime-consumingprocess.

研究生層次的教育通常是必要的，盡管提供基于MEMS學(xué)位的大學(xué)數(shù)量在增加，但知識的積累是一種昂貴的和費時的過程。

(1)?Whathasbeenidentifiedasoneofthemostpromisingtechnologiesforthe21stCenturyandhasthepotentialtorevolutionizebothindustrialandconsumerproductsbycombiningsilicon-basedmicroelectronicswithmicromachiningtechnology?()

A.?MST. B.?MEMS.

C.?DARPA. D.?ASIC.Questionsan