微電子工藝課件

PhotoLithographyTextBookSemiconductortechnologyisverycomplicateandneedcarefulhandlingwhenAllEngineersdoinghisownjobinCleanroom.I’llprepareallkindsoftechnicalmaterialforthispurpose.Itcoversfrombasicitemstoadvanceditems.IhopethismaterialswouldbeusefulforallLithographyEngineers(Process&Equipment)I’mveryappreciatetohaveachancetosummarizethisdata.Icansaytoeveryonethatit’snotperfectmaterialbutbestone.Thankyouforyourhelp.2002.4.1AlbertChang

PrefaceLithographykeywordsdefinition1[1]Designrule:(D/R)Definition:It’susuallydefinedthat“Halfpitchsizeofgatemask(Gatelineisthemostcriticallayer)Thisisthereferenceofsemiconductortechnology:25Logic,22DRAM,18DRAMetcKeyfactorstodecideDesignrule:Lightsource,Lensperformance,Resist,Enhancedprocesstechnologyetc[2]NA(NumericalAperture):Definition:Light-gatheringPower==>beproportionatetodiameterofLens(Maxvalueis1)ThisisthebarometerofResolution(Designrule):DoF=k2*(λ/NA2),R=k1*(λ/NA),KeyfactorstoincreaseNA:Lenspolishingtechnology(toControlAberration)[3]PR(PhotoResist):Definition:Photoactivatedmaterials:Usemajor3componentsandhave2typesDifferenttechnologybydifferentlightsource:g-,I-,KrF,ArF,X-ray,e-beametcThisisthe2ndimportanttechnologytoincreaseResolution[4]ARC(Anti-reflectivecoatingmaterial):Definition:Akindoffilmthatreducelightreflectiveproblem(BARC),Standingwaveeffect(TARC)BARC,TARCforeachwavelength(I-line,KrF)==>BARCisusefulforL/S,TARCisforHoleprocessTARC:Watersolublematerial,BARC:Organicmaterial(Useoxideetchantavailable)DemeritforTARC:Defectsource(Bubbleissues),forBARC:AddetchprocessandparticlesourceMerit:GoodCDcontrolandreducepatternnotchproblemThesmallerwavelength,thebiggerreflectiveproblemDyedresistisonekindofARCprocessLithographykeywordsdefinition1[5]AberrationDefinition:thestateofAbnormalopticalcondition,path;It’srelatedtolenspolishing&assemblyaccuracyTherearearound6kindsofAberration:(1)SphericalAb.,(2)Coma,(3)FieldCurvature,(4)Distortion,(5)Astigmatism,(6)ChromaticAb.Thisisnoteasytoimproveafterlensassemblyfinished:BecausethiscomesfromlensitselfThisisthereasonwhyLensevaluationspecificationissoimportant[6]OAI(Off-AxisIlluminator):Definition:Akindofspecialilluminationmodetoimproveprocessperformance

(DOF).Ingeneral,thereare3kinds:smallσ,Quadruple,AnnularThistechnologyisveryusefulandeasytouse,butbadthroughput(~30%Intensitydecrease)[7]PSM(Phaseshiftmask):Definition:Phaseshiftershift180olightphase,it’scontrolledbythicknessofshifterandrefractiveindexThismaskenhancepatternresolution:Thereare2kinds:AttenuatePSM(HalfTone),AlternativePSM

(Levenson)HalfTonePSM:GoodforHolepattern,butithassideLobeissue(Controlledbymaskbiasandtransmittanceratio)LevensonPSM:Stillithaslotsofproblem.It’susefulforrepeatingpattern;Stillit’snotsopopular.Conventionalmask:WejustcallitBinarymask[8]ContrastCurve:Definition:Thetoolofresistsensitivity(D0orE0)anddevelopersolubilitycheck(Contrast:γvalue)E0isdecidedbyResistsensitivity(Dose-to-clear):Eop(Dose-to-print)=1.6~2.2xEoγvalue=Indexofdevelopingpower;Thehigher,thebetter(Clearedgecut)MaskTechnologyOverview[1]Maskprocessoverview(Binary&AttenuatePSMmask)BlanketMask←Cr+CrOX←Quartz←Resist←Cr+CrOX←Quartz←Resist←Shifter←Cr+CrOX←Quartz←Resist||||||||||||||||←Cr+CrOX←Quartz←Resist←ShifterExpose&Deve-beamwritere-beamresist&Dev←Cr+CrOX←Quartz←Resist←Cr+CrOX←Quartz←Resist←ShifterCrEtch←Cr+CrOX←Quartz←Resist←ShifterShifterEtchPR&Crstrip←Cr+CrOX←Quartz←Quartz←Shifter(1)BinaryMask(BIM)(2)AttenuatePSM(HT-Allarea)2MaskTechnologyOverview[1]MaskprocessoverviewBlanketMask←Cr+CrOX←Quartz←Resist←Shifter←Cr+CrOX←Quartz←Resist←ShifterExpose&Dev←Cr+CrOX←Quartz←Resist←ShifterCrEtch←Cr+CrOX←Quartz←Resist←ShifterShifterEtchPRstrip←Quartz←Shifter||||||||(3)AttenuatePSM(HT-Partialarea)

←Quartz←Shifter←Cr+CrOX←Cr+CrOX←Resist←Quartz←Shifter←Cr+CrOX←Resist|||||←Quartz←Shifter←Cr+CrOX←Resist←Quartz←Shifter←Cr+CrOX←Quartz←Shifter←Cr+CrOX2ndcoating2ndE-beamDevCrWetEtchPRstrip2MaskTechnologyOverview[2]PrincipleofAttenuatePSManditscharacteristic(1)PrincipleEI+-+-SideLobeAreaThisisthereasonwhyedgeprofileissogoodandenhanceDoF(2)CharacteristicsMasktechnologyisnotsodifficultcomparewithlevensonWecanchoosetransmittanceofshifter(8%,4%etc)Especiallythisisgoodforcontacthole,ButSideLobeisbiggestproblem(Almostclearedthisproblemnow)ToprotectsideLobeproblem,weusepartialattenuatePSMmask(ScribelineforBinarymask)Forthefuture,thisismoreusefultoolstoenhanceprocesswindowRecentlywecanuseforL/Sprocesstoo.HowtoreducesideLobe:Optimizetransmittance&resistdissolutionrateadjustment2MaskTechnologyOverview[3]ComparewithAlternativePSMandBinarymaskonwaferLENSBinaryMaskE-fieldI-fieldCrQzLight00+onwaferonwafer0AlternativePSMCrQzLightShifterLENS0+-onwafer

AlternativePSMmaskissues

Maskdesignandfabricationisnoteasy(especiallyshifter)Wecangetfantasticresolution,butthereareghostpatternatpatternedge(Lowenergy).Tosolvethisproblem,highperformanceNegativeresistweneed.ThisisnotgoodperformanceforisolatedpatternStillthistechnologyisnotpopular.2Photoin-lineprocessflowoverviewDefinition:PhotolithographyIt’spatternprintingprocessontheresistcoatedwaferbyUVexposureandpatterndesignedmask(Reticle).WaferFilmFilmDepositionWaferFilmPhotoresistResistCoatWaferFilmPhotoresistUVExposurehvReticleWaferDevelopingFilmWaferEtchGasEE/FOOLBaseLine/FBMix&Match(System)PatternSizeControlPatternProfileControlAlignControlbetweenlayerPhotoJOBFACTORProcessconditiondependsonwhichlayer:Substratecondition,CD,Topology,OLtarget,EtchtargetetcKeyprocessfactor:Tpr(A),UseBARCornot,SB,TARCornot,WEE,EE,FO,OLoffset,PEB,Dev.Dippingtimeandsoon.Keymachinefactor:Cupexhaustpressure,Waterjacketcontroltemp,Chamberpressure,Temp,focus,Plateexhaust,PEBtempAccuracy.[1]GeneralFlow3Photoin-lineprocessflowoverviewHMDScoatCooling1PRCoat(**)SoftBakeCooling2WEE($)EGAalignExposureHardBakeDevelopingP.E.B($$)Scope($$$)OLmeasureCDmeasureIonImpEtchReworkDepositionEXPOSURETRACKPRstripIN-LINECoolingBARCTARC(***)BAKE(*)stepper(*)AbsolutelyweremovemoistureonthewaferbeforeBARCcoating:Secondaryreaction(**)EBRisnotabsoluteprocess:WecanuseWEEinsteadofEBR==>Needrecipetuning(***)TARCshouldbecoatedafterPRbake(Softbake):DonotTARCbake(Secondaryreaction)($)WecanchangefrombeforeexposuretoafterexposureforI-line,butDUVcannot.($$)PEDcontrolisveryimportanttomaintainprocessperformanceforDUV,butI-lineisn’t.($$$)ADIprocedureisimportanttoreduceADIloss:Scope==>OL==>CDBAKE3Photoin-lineprocessflowoverviewHMDSCoatToenhanceadhesionbetweenwaferandresist:MakehydrophobicpropertyUseN2bubblinginthevacuumchamber:Particleissuehappenwhenlowvac.Usually130oCplatetemp.isoptimumconditionCooling1Hightemp.ofwaferisnotgoodforcoatinguniformityUsuallyroomtemp(23oC)isoptimumcondition:Dependonresistanditstks.PRCoatSoftBakeCooling2Usesteppingmotorchemicalpump:ControldispenseamountanditsspeedProcessEBR/backrinsetoremovedummyresist:WEEcandoinsteadofEBRUniformityfactor:PRtemp,wafercool,cupexhaust,T&H,Chucktemp,Resistsolventremove,relaxtheresiststressSettingtemp:80oC~130oC==>SolventB.Pisaround150oC,thereforeit’simpossibletoremovesolventperfectly.Toremovemisalignproblem:Wafermag.,scale,rotetcRoomtemp.isOK(23oC)Havetomaintainsametemp.foreachwafer.[2]CoaterFlow3Photoin-lineprocessflowoverviewP.E.BStandfor“PostExposureBake”==>I-line:ReduceStandingWaveeffect==>DUV:DiffusePhotoAcid(Coreprocess)RootcauseofStandingWave(I-line)撩碟醞

==>DifferentconcentrationofdissolvedPACbecauseoflightwavePEBtemperatureofDUVdecideCDanditsprofile:ItdependonresistNeedtoevaluateoptimumTemp:BelowPACdissolutionTemp(130oC)I-line(110oC~120oC),DUV(110oC~130oC)areoptimumTemp.CoolingToimproveDevelopuniformityOptimumTemp:23oC(roomtemp)/60secDevelopHardBakeImprovePRhardening&Adhesion,Removewater&Solvent,Butthisisnotnecessary.(I/Ilayerisnecessary:Outgassingissue)Usuallyunder130oCNormallyweuse2.38%moleconcentration:I-line/DUVForspecialDUVprocess,weuse1.914%TMAHDeveloper.ThisisonlyforhighspeedDUVresist(Localsupply)Bake[3]DeveloperFlow3Photoin-lineprocessflowoverview(Detail)ADHESIONToenhanceadhesionbetweenwaferandresist,wetreatvaporizedHMDS(HexaMethyleneDiSilazane)onthewaferandmakeithydrophobicstateHydrophilicSurfaceSubstrateSiSiSiSiOOOO(H3C)3Si(H3C)3Si(H3C)3Si(H3C)3Si⊿T-nNH3HydrophobicSurfaceLowContactAngleHighContactAngleSubstrateSiSiSiSiOHOHOHOH(H3C)3SiSi(CH3)#NH(H3C)3SiSi(CH3)#NHBubblingN2N2HMDSINHMDSOUT~~N2+HMDSBubblingSystemHMDSitselfisLiquidstate.WecanmakevaporizedHMDSbyN2bubblingsystem,andtreatthisgasinthevacuumCh.[1]Adhesion(HMDS)*Wecancheckwafersurfaceconditionbycontactangle*Needtocleanthevaporizedgassupplypipetoremoveparticlesource3Photoin-lineprocessflowoverview(Detail)*StaticmodeisusefulforHighviscosityResist,andDynamicforlowviscosity[1]Adhesion(HMDS)HowtocoatSpinoncoatingmethod:2kindofmethods(1)Dynamic:Resistdispenseonrotatingwafer,(2)Static:Dispenseonstoppedwafer企2企3企1t2t1t3t4SPINSPEEDTIMERESISTDISPENSINGEDGEBEADREMOVINGRESISTCoatingCYCLE(Conventionaltype)r1r2r3r4r5ThiscycleisconventionaltypecycleCurrentlyallresistpumprecipeisnotthistype.1.DispenseRPMislow2.ThicknessisdecidedbyHi-RPM3.Resistviscosityisimportanttodecidethicknesstarget==>Hi-RPMcancoverunder3000Athicknesst1:RESISTDISPENSETIMEt2:HIGHRPM(Decidethickness)t3:SIDE/BACKRINSETIMEt4:SOLVENTDRYTIMEt=√rpmkS2t:RESISTthicknessS:%ofresistsolidk:SPINCOATERConstant[2]PRcoatingcycle(Conv.)3Photoin-lineprocessflowoverview(Detail)*Weneedspecialresistpumpsystem(steppingmotorpumpandprewetdispensesystem)*Needveryhighspintoreduceresistamount.(~3500RPM)[1]Adhesion(HMDS)HowtocoatSpinoncoatingmethod:2kindofmethods(1)Dynamic:Resistdispenseonrotatingwafer,(2)Static:Dispenseonstoppedwaferω2StaticSPINSPEEDTIMERESISTDISPENSINGBRRESISTCoatingCYCLE(Solventprewettype)ThiscycleissolventprewettypecycleSolventprewetenhancesPRspreadout.1.Dispenseamountislow2.ThicknessisdecidedbyHi-RPM,buttherearelimitation(NeedtochangePRviscosityifwewanttochangeover1000Atarget)3.Resistviscosityismostimportanttodecidethicknesstarget4.Needtoremoveprewetsolventalmost.(justenhancePRspreadout)[2]PRcoatingcycle(Prewet)ω1ω1SolventPreWetEBRBRBR3Photoin-lineprocessflowoverview(Detail)[3]PRThicknessuniformityparameterParameterAveragethickness:Viscosity&spinspeedUniformity:Resist&Environmenttemp,wafertemp,motorflangeetcParameterWhenCoolingtempishigherthanopt.WhenPRtempishigherthanopt.Whencupexhaustishigherthanopt.Whencuphumidityishigherthanopt.Whenmotorflangetempishigherthanoptimum.CenterEdgeWhencuptempishigherthanopt.NoinfluenceOnlyChuckedgebecamethickthicknessInawaferWithinwafermapResisttempvsWFavgtks0204060802223242526Resisttemp(℃)PRtks(A)020406080100120212223242526CoolingtempvsWFavgtksPRtks(A)Cooltemp(℃)3Photoin-lineprocessflowoverview(Detail)[4]PRThicknesstargetfactorCurrentPRTargettrendThintargettrend:Toenhanceprocesswindow.PRselectivityimproved(StillmetallayerusethicktargetChoosevalleyorhillofS/WCurve(bare):StableCDuniformity==>Recentlyfilmwaferevaluatetrend(1stlayer)StandingWaveCDBalance(Bulkevaluation)EtchSelectivityEnhanceResol.LowPRselectivityfilm:Thicktarget(e.gMetallayer)I/Icondition榆Tocovertopologyinfluences,weneedbulkevaluationDRAMgatelayerisnecessary(Yield&device’sspeed)HighenergyI/IlayerneedthickfilmtocoverbreakthroughThroughputThinPRfilmisnecessarytogethighresolutionTodecreaseExposeenergy,thinPRfilmisbetter3Photoin-lineprocessflowoverview(Detail)[5]SolventdistributioninPRfilmSolventconc.vsBAKETempSolventconcentrationtrendinPRfilmBAKETempvsRESISTThicknessResistconsistsofResin,PACandover80%ofsolvent.SolventconcentrationiskeyfactorofPRthicknessSolventCon.SOFTBAKETempSOLVENTcon.BEFORESOFTBAKEAFTERSOFTBAKESUBSTRATERESISTFILMLOSSRESISTTHICKNESSSOFTBAKEtemp125~130﹎ReciprocalproportionbetweenbaketempandsolventconcentrationBeforesoftbake:Lotsofsolventininternalresistfilm,andsteeplydecreaseneartheresistsurfaceAftersoftbake:Evaporatedsolventininternalresistfilm,andit’llbepeakneartheresistsurfaceSoftbake==>SolventEvaporation==>Thicknessdown,DensityupWhenwebakeoverTgtemp,PACwillbedestroyedandplasticflowwillhappeninresistfilm.Sothicknesswillbesteeplydecreased.GLASSTRANSITIONTEMPERATURE3Photoin-lineprocessflowoverview(Detail)[6]Developmentparameter(1)DeveloptimevsRprDeveloptimevsprofile鼻衛(wèi)除vs鼻樓紫Rpr(exparea)time(sec)PROFILE5060409070Optimumtimetime(sec)Tprtime(sec)E3E2E1E1<E2<E3WecanuseDRMsystemforthisone.ItdependonEE.Usuallyit’sunder20secdippingtime.Thisisthestandardtooltodecidedevelopdippingtime.UnderDevelop:ScumandtailOverDevelop:TopprofilecollapseUsually40~60secdippingisstandarddipping(dependonPR)EEvs.RprrelationshipCDwillbedecreasedbydippingtimebutsaturationtimeisaround30secdip.0t13Photoin-lineprocessflowoverview(Detail)[7]Developmentparameter(2)DevelopNormalityvsCONTRAST滲NORMALIZDTprDeveloptimeLowNormalityDev:NeedlongDevtime,gethighcontrast.ThisisgoodforperformanceHighNormalityDev:ShortDeveloptempvsDevelopspeed(rate)DEVELOPRATETEMPERTUREDeveloptemperatureisoneofimportantitemtocontroldeveloprate.Ithasoptimumtemp.ButTomaintainconstanttemperatureisnoteasy.Itdependonspraytypeandnozzletype.UsuallyEngineerneedtofindoutoptimumtemp.Butusuallywecanuseroomtemperaturebecausethistemp.isthemoststabletemperature.ABCNormality:A<B<CCONTRAST:C<B<AE/E:C<B<A3ExposureProcessFlow[3]Exposeshot&Area(Shotdesign)ShotStepper:31.1mmmaximumfieldsize,Xmax=22mm,Ymax=NAOnwafer

Scanner:Xmax=26mm,Ymax=33mmOnwaferscribelineCrReticleDesignAlignKeyTegMonitoringPadReticleAlingkeyCrGuardRingchipchipchipchip1234DoubleExpoAreaExpoDoubleExposeArea:BothofonecoveredbyCr.GuardRing:ProtectblindsettingerrorXmaxisbecauseofReticlealignkeySHOT*WidthofScribelineisdecidedbydesigner,buttherearelimitwidth:Usually90~120umscribeline*Maskalignkey:Machinedependency==>ASML,Nikon,CanonSVGLetctotaldifferent4ExposureProcessFlow[5]ExposingtechnologyOverviewConventionalAnnularQuadrupleMaskWaferFLEXNA/OptimizationHighResolutionMaterialResistProcessTechnologyOff-AxisIlluminationPhaseShiftMask/OPCMultipleExposureOthersMaskPhase018001800180OPC*d=/2(n-1)4ExposureProcessFlow[5]ExposingtechnologyOffAxisilluminator(1)Illuminatorsendtiltlighttolenssitebyspecialaperture(Centerclosed)Aperturecancut-1stlightamong-1,0,+1stdiffractedlightOnlyuse0&+1storderlightforimageexposingComparewithConventional,DiffractionAngleissmall:HiR&wideDoFIntensitydegradebecauseof-1storderdiffractedlight(~30%)TheoryOAIApertureMask-1storder+1storder0orderNAlensWaferLensSin=n伙/Pn:0,1,2颻..P:PitchSize:DiffractionangleConventionalApertureMask-1storder+1storder0orderNAlensWaferLens4ExposureProcessFlow[5]ExposingtechnologyOffAxisilluminator(2)ConventionalAnnularQuadrupleEffectImproveResolutionImproveD.O.FItcan’tprintsmallsizepattern(>0.2um)becauseoflargediffractionAng.BadResolution/D.O.F盪OAI45PatternDefinebad碳榆PatternDeformationBigeffectofLensAber.ThroughputdegradeLimitationLimitationAperturetypeConventional4ExposureProcessFlow[5]ExposingtechnologyOffAxisilluminator(3)QUADRUPOLEANNULARLOWHIGHLightpathLightpath4ExposureProcessFlow[5]ExposingtechnologyPSM(1)onwaferLENSConventionalMaskPhaseE-fieldIntCrQzLight00+onwaferonwaferPhaseE-field0PSMMaskCrQzLightShifterLENSInt0+-onwaferPSM(PhaseShiftMask)ThisisforResolution&DoFenhancement.Itusephaseinterference4ExposureProcessFlow[5]ExposingtechnologyPSM(2]TheoryDifferentrefractiveindexmaterialuseasshifter(n=1.5==>shift豇OpticalPathLength=nxdOpticalPathDifference=dxn-dx1=伙/2MaskSubstratePhase"0"Phase"180"PhaseShifterDirectionofLightPropagationElectricfieldR.I(n)=1.5R.I=1.5R.I(n)=1.04ExposureProcessFlow[5]ExposingtechnologyPSM(3]0.250.500.75RESOLUTION(um)EQUIPMENTG-lineI-lineI-lineDUVI-linePSMCrmaskDOF(um)EQUIPMENT2.01.51.00.5CrmaskPSMPSMeffectHighResolutionWideDoFG-lineI-lineI-lineDUVI-line4ExposureProcessFlow[5]ExposingtechnologyPSM(4)CrmaskLevensonPSMOutriggerPSM180oshifterQuartzQuartzQuartzCrosstargetGood&BadGeneral(Bin)撩ResolutionLimitEasymakingForLine&SpaceForContactPSMtype&itscharacteristicHalf-tonePSMForContactResolutiongreatHardmakingResolutiongoodMostHardmakingResolutionimproveEasymaking4ExposureProcessFlow[5]ExposingtechnologyPSM(5)Limit&itssolutionProcess/EquipNeedsPSMdesign啗&SimulationMasklayoutDummyline&patternTransmittance&PhaseMaskmachineproblem撿

LowperformanceofinspectionMCLowperformanceofdefectrepairMCExposuremachine(Stepper)Needgoodill.unif.AtLow&N.ANeedgoodill.unif.AtHigh&N.AHighperformanceresistHighqualitynegativeresistLayoutlimitationbecauseofproximityeffect-It’snotsuitableforLOGICdeviceProcesscontrolNeedtoughMaskCDspecNeedDefectfreemaskProcessdefectminimizeNeedHighresolutione-beamMCDummypattern<0.75um

(Levenson&OutriggerPSM)4ExposureProcessFlow[5]ExposingtechnologyOPCAddorremovedummypatternatpatternedge,soastoprintalmostdesignedpatternonthewaferTargetPRPatternPRPatternConventionalMaskOPCMaskCrReticleCrReticleSmallMarginMarginEnlargeHoleHole*Thistechnologyisveryusefulbutit’sverydifficulttomakemask(Defectfree)4ExposureProcessFlow[6]StepperBasicNANA(NumericalAperture)?Aperture(NAill)CollimatorLensReticleProjectionLensApertureStop(NAlens)WaferNA=d*sinNAisthediameterofaperture(Itrestrictlightpath)Thereare2kindofNA:illuminationNA&LensNA.UsuallyNAmeansLensNA.CurrentallmachineadoptedvariableNA:UserchooseNA.NA=d/2fImagePlaneLens玄fdNA=n*sinn:AirR.I(1)4ExposureProcessFlow[6]StepperBasic(Coherence)<1>(Coherence)?Aperture(NAill)CollimatorLensReticleProjectionLensApertureStop(NAlens)Wafer=NAill/NAlensLightinterferencebetweenpath1andpath2,3lightistherootcauseofimageplanedistortionWhenwereducelensaperturediameter,wecancutpath2&3light(Reducelightinterference)WhenitcomestoCoherence,idealis0,usually0<<1(PartiallycoherentNA

豇ImagePlanePath1Path2Path3LensNA

幙4ExposureProcessFlow[6]StepperBasic(Coherence)<2>relationshipBigGOODHIGHGOODSmallContrastIntensityUniformitySpecialFrequency=1=0=0.2=0.6(conventional)=0==>GetidealImageMTF(MultipleTransferFuntion)Smallisnotalwaysgood.WehavetochooseoptimumDifferentchangeimagefield(mismatchisoneofmisalignreason)NAill=ChangebyHWapertureNAlens=Freelychange4ExposureProcessFlow[6]StepperBasicResolution&DoF<1>Resolution&D.O.Fhavereciprocalproportionof/NA.It’sverydifficulttoimprovetheseperformance.Togettheseperformance,weuseHiperformanceResist,PSM,OAIandsoon.

R:Resolution

DOF:DepthOfFocus

:WavelengthofExposureSource

NA:NumericalAperture

k1,k2:ProcessFactordecidedbyPR,ARC,PSMOAI,OPC...RelationbetweenRandDoFR=k1*

/NADOF=k2*

/(NA)2NABigGOODSmallResolutionD.O.FGOOD

BigGOODSmallResolutionD.O.FGOOD4ExposureProcessFlow[6]StepperBasicResolution&DoF<2>RelationbetweenRandDoF(nm)365248193NA0.630.60.6K1K21.091.161.31R(um)0.350.250.18DOF(um)1.000.800.70OVERLAY(um)0.1000.0750.0450.630.60.6vsD.O.FvsRESOLUTION00.811.2

(nm)(um)193248365D.O.FRESOLUTIONNAvsD.O.FvsRESOLUTION1.51.7NA(um)0.430.520.540.63D.O.FRESOLUTIONR=k1*

/NADOF=k2*

/(NA)24ExposureProcessFlow[6]StepperBasicLensAberration<1>AberrationInopticsystem,itmakesabnormalfocalplane.Actuallyallkindoflenshaveaberration.kindsMonoChromaticAberrationChromaticAberrationSphericalAberrationComaAberrationAstigmatismFieldCurvatureDistortionImagebecomeblurImagebecomedistort*LenspolishingaccuracyandassemblyaccuracyismajorreasonofAberration*Insemiconductorbusiness,mostimportantpointisHowtochooselowaberrationmachine.Becauseaberrationcannotimprove,it’snotrepairableproblem.*EspeciallyCOMAisbigprobleminOLcontrol(PatternalignandOLdataunmatch)4ExposureProcessFlow[6]StepperBasicLensAberration<2>*ThisaberrationismoreimportantoneinLogicdevicesFab.Becausetherearemanydifferentpatternsizecircuitinonemask.*Evaluatespec:MinimumsizeCD(0.18~0.20)and0.5umpatternSphericalAberrationFocalpointisdifferentbetweenpath-Aandpath-Bontheopticaxis.Bending:BestForm(Lensformthatminimizesphericalaberration)dependoninputlightUseGradientIndexLens(differentrefractiveindex)ImagePlaneCDFocusWecangetdifferentbestfocusbetweenpatternsize(CD)Thesmallergap,thebetterBestFocusGapHowtocheckonwaferBendingHowtoremoveLowrefractiveGradientIndexLensHighrefractiveHowtoremove4ExposureProcessFlow[6]StepperBasicLensAberration<3>*Easytofindoutthisaberration:WecanmeasurePatternslopeonright/leftside(ortop/bottom)*Thisonegivemoreseriousattackinfinepattern(Under0.2um):ShouldminimizeCOMAlevel.ComaObjectisnotontheOpticaxis.Itisnotfocalimagebutcometontheimageplane.Thisaberrationcanbeminimizedbylensassembly.BendingCombinationofLensUseAplanatopticsystem(Spherical&Comaisperfect)ImagePlaneHowtocheckonwaferIn-FieldHoleLineOff-axisComa:NodirectionalAberration,NocorrectableOn-axisComa:directionalAberration,CorrectableonebybendingglassDirectional爾薑

寞徹Object4ExposureProcessFlow[6]StepperBasicLensAberration<4>*Easytomaketroubleatfieldedgearea*Especiallythisoneisfataltroubleincontactprocess:DifferentshapeindifferentpositionAstigmatismIncoherentfocalplanebetweenTangentialandSagittalImage.ImageplaneisinConicoidarea.conicoidareaSagittalsurfaceTangentialsurfaceTangentialPlaneSagittalPlaneHowtocheckonwaferCheckbestfocusatHorizental/Vertical/Sigittal

PatternHoleshapedistortedbythisaberrationeventhoughatBFBestFocusNormalAbnormalAstigmatism4ExposureProcessFlow[6]StepperBasicLensAberration<5>*Usuallycenterpositionoflensisdifferentfromedgearea:0.2~0.3umdifference*It’stoodifficulttocompensate:Usuallywecheckthisby5point(or9point)TotalDoFcheck.FieldCurvatureDistortionofImagefieldexcludeCOMAandSphericalAberrationTS:SS=3:1SurfaceplanepetzvalsurfaceSagittalsurfaceTangentialsurface13HowtocheckonwaferCheckthebestfocusateachpositionwithinimagefieldPetzvalSurface╮2dimensionalsurfaceplanethatlengthratiois3:1betweenTangentialandSagittalsurfaceBestFocusPositioncenterlefttopleftbottomrightbottomrighttop4ExposureProcessFlow[6]StepperBasicLensAberration<6>*Recentlyitwouldbeadjustedbycomponentlensadjustment*ThisisoneofthekeyaberrationinlenssystemDistortionThelightpathgapbetweenidealandreallightpath.ImageMag.isdifferentbymeansofinputlightangleHowtocheckonwaferImagePlaneStopRealimageIdealimagePIN

CUTIONChiefRayImagePlaneStopIdealimageRealimageBARRELChiefRayCheck49pointOL.ResidualfactorexcludeCRandC.magRandomdistributioninonefieldExposu