半导体工艺Photo.ppt

1、b,1,IC工艺技术系列讲座第二讲,PHOTOLITHOGRAPHY光刻,b,2,讲座提要,1.General2.Facility(动力环境)3.Mask(掩膜版)4.Processstephighlight(光刻工艺概述)5.BCD正胶工艺6.Historyand未来的光刻工艺,b,3,1.General,MASKINGProcess(光刻工艺)Photolithography(光学光刻)-Transferatemporarypattern(resist)DefectcontrolCriticaldimensioncontrolAlignmentaccuracyCrosssectionpro

2、fileEtch(腐蚀)-Transferapermanentpattern(Oxide,Nitride,Metal),b,4,2.0Facilityrequirement,Temperature(温度)70oFHumidity(湿度)45%Positivepressure(正压)0.02in/H2OParticlecontrol(微粒)Class100Vibration(震动)Yellowlightenvironment(黄光区)DIwater(去离子水)17mhomCompressairandNitrogen(加压空气,氮气)Inhousevacuum(真空管道),b,5,3.0Mask(

3、掩膜版),DesignPGtapeMaskmakingPlate-quartz,LEglass,SodalineglassCoating-Chrome,Ionoxide,EmulsionEquipment-E-beam,PatterngeneratorMaskstorage-AntistaticBox,b,6,Pellicle,b,7,Pellicleprotection,b,8,4.0光刻工艺概述,PrebakeandHMDS(前烘)Resistcoating(涂胶)EBR(去胶边),softbake,3.Exposure(曝光)Alignment(校正)4.Develop(显影)Poste

4、-bake,Hardbake,backsiderinse5.Developinspection(显检),b,9,4.1PrebakeandHMDStreatment,PurposeofPre-bakeandHMDStreatmentistoimprovetheresistadhesiononoxidewafer.HMDSisadhesionpromoterespeciallydesignedforpositiveresist.HMDS(Hexamethyldisilane)canbeappliedonthewafersby1.Vaporinabucket2.vaporinavacuumbox3

5、.Directlydispenseonwafer4.YESsystem-inahotvacuumsystem5.Vaporinahotplate(withexhaust)ToomuchHMDSwillcausepoorspin,viceversawillcauseresistlifting,b,10,4.2ResistCoating(涂胶),Resistcoatingspecification(指标）Thickness（厚度）0.7u2.0u(3.0以上forPadlayer)Uniformity（均匀度）+50A+200ASizeofEBR（去胶边尺寸）Particle（颗粒）20perwa

6、ferBacksidecontamination(背后污染）三个主要因数影响涂胶的结果ResistProduct(产品）Viscosity（粘度）SpinnerDispensemethod（涂胶方法）Spinnerspeed(RPM)（转速）Exhaust（排气）Softbaketemperature（烘温）FacilityTemperature（室温）Humility（湿度）,b,11,4.2.1Coater(涂胶机）,EquipmentmoduleandspecialfeaturePre-bakeandHMDS-Hot/ColdplateResistdispense-ResistpumpR

7、PMaccuracy-MotorEBR-Top/bottomHotplate-softbaketemperatureaccuracyExhaustWastecollectionTemperature/HumiditycontrolhoodTransfersystem-ParticleandreliabilityProcessstepandprocessprogram-Flexible,b,12,SVG8800,升降机,涂胶,HMDS,热板,冷板,升降机,升降机,升降机,涂胶,热板,热板,升降机,升降机,升降机,升降机,涂胶,热板,冷板,HMDS,冷板,冷板,冷板,涂胶,热板,热板,升降机,升降

8、机,显影,热板,热板,热板,冷板,4.2.2Coater(涂胶机）combination,b,13,4.2.3Coater(涂胶机）,ResistdispensemethodsStaticDynamicRadialReverseradialResistpump(Volumecontrol-2cc/waferanddripping)Barrelpump-TritekDiaphragmpump-MilliporeN2pressurecontrolpump-IDLStepmotorcontrolpump-Cybotsizeofdispensehead,b,14,4.2.4Coater(涂胶机）,rp

9、m(转速）andacceleration（加速）Maximumspeed-Upto10000rpmStability-daytodayAcceleration-controllablenumberofstepsReliability-timetoreplacementEBR(Edgebeadremoval)（清边）Method-TopEBRorBottomEBRorTopandbottomEBRProblem-DrippingChemical-Acetone,EGMEA,PGMEA,ETHLY-LACTATE,b,15,ResistType,NegativeresistPositiveresi

10、stG-lineilinereverseimageTAC-topanti-reflectivecoatingBARLI-bottomanti-reflectivecoatingChemicalamplificationresistXrayresist,b,16,4.3.1Exposure(曝光),Transferapatternfromthemask(reticle)toresistGoal1.CriticalDimensioncontrol(CD)条宽2.Alignment校准-Mis-alignment,runin/out3.Patterndistortion图样变形-Astigmatis

11、m4.Crosssectionprofile侧面形貌-sidewallangle5.Defectfree无缺陷Equipment/mask/resistselection1.Resolution分辨率-Exposecharacter,Lightsource(wavelength),N/A,2.Auto-alignmentskill自动校准技术-Lightfield,darkfield,laser3.Mask掩膜版-e-beammaster,sub-master,spotsize,quartzplate,defectdensity,CDrequirement4.Resistselection胶选

12、择,b,17,4.3.2Exposure(曝光),AlignerTechnology1.Contactprint(接触）Softcontact,hardcontact,proximity2.Scanner(扫描）3.Stepper(重复）1X,2X,4X,5X,10X4.StepScan(重复扫描)4X-reticlemove,wafermove,reticle/wafermove5.Xray(X光）1:16.E-beam(电子束）-Directwrite,b,18,4.3.3Exposure(曝光),Contactprint(接触）1.Mostofusefornegativeresistpr

13、ocess-for5uprocessandcanbepushto3u.2.Positiveresistcanprintsmallerthan3u,anddeepUVcanpushto1u,butveryhighdefect3.Equipment:-CanonPLA501-Cobilt-Kasper-Kinthisfirstprocess,thepattern,orimage,wastransferredfromastoneplate(thewordlithocomesfrom).Thefirstpracticaltwodimensionaldevicepatterningonasiliconw

14、aferwasactuallycarriedoutinthelate1940sattheBellLab.Atthattime,polyvinylcinnamate,developedbyEastmanKodak,wasusedasaresist.However,deviceyieldswerelowbecauseofthepooradhesionofthepolyvinylcinnamatetothesiliconandoxidesurface.TheKodakchemiststhenturnedtoasyntheticrubberbasedmaterial-apartiallycyclize

15、disopreneandaddedaUVactivesensitizer-abis-aryl-azideintoittocrosslinktherubbermatrixandcreatedanewclassofphotoresistmaterial.Sincetheunexposedareaofthenewmaterialwastheonlypartofthepolymermatrixthatwilldissolveinanorganicsolventandyieldinganegativeimageofthemaskplate,therefore,thenewmaterialwasthenr

16、eferredasthenegativeresist.Thecyclizedrubber/bisazideresistwaswidelyusedinthecontactprintingage.However,thecontactmodeofprintingcreatedseverewearofthemaskplateandthedefectdensityofthephotomaskandthewaferwasveryhigh.Theindustrythereforedecidedtoswitchtocontactlessprojectionprintingin1972forproducingt

17、he16kDRAM.Projectionprinting,however,wascarriedoutintheFraunhofferorthesocalledfarfielddiffractionregionandtheaerialimagewasmuchpoorerthanthecontactorproximitymethodofprinting.Inordertopreservethesamequalityofimagestructure,thecontrastoftheimagematerialmustbeincreased.,b,68,Lithographiclorehasitthat

18、thediazonaphthoquinone/novolakresist(thetermnovolakisderivedfromtheSwedishwordlak,meaninglacquerorresinandprefixedbytheLatinwordnovo,meaningnew)madetheirwayfromtheblueprintpaperindustrytothemicroelectronicthroughfamilyties:atthattimes,theofficesofAzoplate,theAmericanoutletforKalleprintingplate,waslo

19、catedatMurrayHill,NJ,justacrossthestreetfromthefamousBellLabs.ThefatherofatechnicianatAzoplateworkedasatechnicianatBellLabs.ApparentlythefatherhadcomplainedonedayaboutthepoorresolutionqualityofthesolventdevelopedresistsystemusedattheBellLabsandthesonhadboastedthepropertiesoftheAzoplateDNQ/novolakmat

20、erial;anyway,onedaythefathertookabottleofthematerialwithhimtotheBellLabs,andtheageoftheDNQ/novolakresistbegan.ThenewmaterialwasmarketedbyAzoplateunderthetradenameofAZphotoresist.Itwasalwaysreferredasthepositiveresistforapositivetoneofimagewouldbereproducedbythenewmaterial.TheuseofDNQ/novolaksystemin

21、creasedrapidlyaftertheintroductionoftheprojectionlithography.By1980s,theDNQresisthadcompletelysupplantedtheoldnegativeresistastheworkhorseofthesemiconductorindustryinthehigh-endapplications.TheDNQ/novolakresisthasheldswayfor6devicegenerations,fromtheintroductionofthe16KDRAMtothelargescaleproductiono

22、fthe64MDRAMin1994to1995.Thesuccessofsuchmaterialwastheindicativeofitsupremeperformanceandpotential.Today,itappearsthatitisnotreallytheresolutionwhichdefinesthelimitoftheDNQ/novolakresistapplication,butratherthelossinthedepthoffocuswiththeeverincreasingNAofthestepper.DeepUVandchemicalamplificationneg

23、ativetoneresistslowlyerodethemarketplaceoftheDNQ/novolakresist.Bytheendofthe1990s,theDNQ/novolakresistwasnolongerbeusedinthetechnologicallymostadvancedapplications-theprintingofthecriticallevelsofthe256MDRAM.,b,69,6.2Future,IntroductionofnanoimprinttechnologyFabricatingmicrostructuresandnanostructur

24、eisimportantinmanyfieldsofscienceandtechnology,includingelectronics,datastorage,flexibledisplays,microelectromechanicalsystems,microfluidics,photonicsandbiosensors.Traditionally,opticalorelectronbeamlithographysystemsareusedtoprinttherelevantstructures.However,newprintingmethodssuchasimprintlithogra

25、phyandsoftlithographyhaverecentlybeenexploredinsomedetailtolowerthecostsoffabricatinglowvolumesofstructureswithverysmallfeaturesandtoincreasetherangeofprintingapplication.Thesoftlithographyschemes,ingeneral,useasofttemplatepatternmadeofsiliconeelastomer,polydimethylsiloxane(PDMS),whichisplacedintoco

26、ntactwiththesubstrateinavarietyofways,topatternasurfacefilm,totransferamaterial,orfordirectintegrationintothefinalpart,witharangeofinnovativeapplications.ChallengesinthisareaaregenerallyconcernedwiththeinherentlimitationsofthePDMSmaterialincludingresolutionlimitationswhencuringduetodifferencesinther

27、malexpansionbetweenthemasterandmold;adhesiontocommonmastermaterialslikesilicon;significanttime,aboutanhour,tofabricateamold;elasticityofthemold,whichmayimpactmultilevelalignment;insolubilitywithcommonsolvents;contaminationissuesandincompatibilitywithsomeorganicmaterials.,b,70,Theimprintmethodsutiliz

28、eheatorUVcurableliquidstomoldpatternsontoasubstratefromarigidtemplate.Researchgroupshavedemonstratedsub-100nmresolution,somehavedownto10nm.Imprintprocess;however,donottransfermaterialsfromthetemplatetothesubstratelikethesoftlithographyschemes.Anotherhesitationwiththeimprinttechniqueconcernsthelifetimeofthemasterpattern.Theproblemissimilartothatencounteredinthecontactphotolithography,whereithasbeenfoundthatthedefectfreelifetimeisonlylimitedtolessthan1000passes,despitetheapplicationofcoatingsandlubricants.Thisconcernarisesfromtheimportantrequirementsthatthesu