《信息科学类专业英语》课件第24章

Lesson24AnIntroductiontoMEMS(Micro-electromechanicalSystems)

(第二十四课微机电系统简介)

Vocabulary(词汇)ImportantSentences(重点句)QuestionsandAnswers(问答)Problems(问题)

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,装配；捏造,虚构,伪造(谎言,借口,文件,签名等)；创立(理论等)。

2. acronymn.只取首字母的缩写词。

3. substraten.(=substratum)底层,地层;【无】(半导体工艺中的)衬[基]底;基片;垫托物;感光胶层;【生态】基层;【生化】基质;被酶作用物;真晶格。

4. electromechanicaladj.[机]电动机械的,机电的,电机的。Vocabulary

5. micropositionern.微型远程位置调节器，微动台。

6. interdisciplinaryadj.各学科间的,跨学科的。

7. unprecedentedadj.空前的;史无前例的;无比的；新奇的;崭新的。

8. synergyn.(=synergism)协同,配合,企业合并后的协力优势或协合作用。

9. overlapvt.与……交搭;叠盖住；(与……)部分相一致(巧合)n.重复,部分一致;交搭;复叠部分,交搭处;覆盖物;涂盖层;【植】盖覆;【摄】重叠摄影;【数】交叠,相交;复合。

10. categorisev.加以分类。

11. radiantadj.辐[放,发]射的,发生辐射热的;发光的;光芒四射的,灿烂的;容光焕发的。

12. commercializationn.商业化。

13. roadmapn.路标。

14. competitiveadj.竞争的，竞赛的；与……不相上下的；经得起竞争的。

15. time-consuming费时的；消耗时间的。

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

采用像堆积和表面显微机械加工工艺，以及高长宽比的显微机械加工(HARM)可选择移动或增加硅晶体部件附加的结构层来形成机械的和电动机械的部件。ImportantSentences

[2]MEMSisamanufacturingtechnology;aparadigmfordesigningandcreatingcomplexmechanicaldevicesandsystemsaswellastheirintegratedelectronicsusingbatchfabricationtechniques.

MEMS是一种制造工艺；一种设计和生产复杂的设备和系统的模式，同时可以通过批量制作技术集成电子器件。

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

微光电动机械系统(MOEMS)是MST的一个子集和MEMS技术融合所形成的光、电和机械小型化的专门技术领域。

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

为了增加改革和创新，以及减少不必要的面市时间代价，应该划分一个分离设计和生产的界线。

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

另外，一个MEMS工业路标组织，由半导体设备与材料国际组织(SEMI)赞助，已经确定共享MEMS在工艺、技术、应用和市场方面面临竞争的信息。

[6]EducationatgraduatelevelisusuallynecessaryandalthoughthenumberofuniversitiesofferingMEMS-baseddegreesisincreasing,gainingknowledgeisanexpensiveandtime-consumingprocess.

研究生层次的教育通常是必要的，尽管提供基于MEMS学位的大学数量在增加，但知识的积累是一种昂贵的和费时的过程。

(1) Whathasbeenidentifiedasoneofthemostpromisingtechnologiesforthe21stCenturyandhasthepotentialtorevolutionizebothindustrialandconsumerproductsbycombiningsilicon-basedmicroelectronicswithmicromachiningtechnology?()

A. MST. B. MEMS.

C. DARPA. D. ASIC.Questionsan