半导体工艺Photoppt课件

IC工艺技术系列讲座第二讲,PHOTOLITHOGRAPHY光刻,1,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,2,1.General,MASKINGProcess(光刻工艺)Photolithography(光学光刻)-Transferatemporarypattern(resist)DefectcontrolCriticaldimensioncontrolAlignmentaccuracyCrosssectionprofileEtch(腐蚀)-Transferapermanentpattern(Oxide,Nitride,Metal),3,2.0Facilityrequirement,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),4,3.0Mask(掩膜版),DesignPGtapeMaskmakingPlate-quartz,LEglass,SodalineglassCoating-Chrome,Ionoxide,EmulsionEquipment-E-beam,PatterngeneratorMaskstorage-AntistaticBox,5,Pellicle,6,Pellicleprotection,7,4.0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-bake,Hardbake,backsiderinse5.Developinspection(显检),8,4.1PrebakeandHMDStreatment,PurposeofPre-bakeandHMDStreatmentistoimprovetheresistadhesiononoxidewafer.HMDSisadhesionpromoterespeciallydesignedforpositiveresist.HMDS(Hexamethyldisilane)canbeappliedonthewafersby1.Vaporinabucket2.vaporinavacuumbox3.Directlydispenseonwafer4.YESsystem-inahotvacuumsystem5.Vaporinahotplate(withexhaust)ToomuchHMDSwillcausepoorspin,viceversawillcauseresistlifting,9,4.2ResistCoating(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）20perwaferBacksidecontamination(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）,10,4.2.1Coater(涂胶机）,EquipmentmoduleandspecialfeaturePre-bakeandHMDS-Hot/ColdplateResistdispense-ResistpumpRPMaccuracy-MotorEBR-Top/bottomHotplate-softbaketemperatureaccuracyExhaustWastecollectionTemperature/HumiditycontrolhoodTransfersystem-ParticleandreliabilityProcessstepandprocessprogram-Flexible,11,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,升降机,显影,热板,热板,热板,冷板,4.2.2Coater(涂胶机）combination,12,4.2.3Coater(涂胶机）,ResistdispensemethodsStaticDynamicRadialReverseradialResistpump(Volumecontrol-2cc/waferanddripping)Barrelpump-TritekDiaphragmpump-MilliporeN2pressurecontrolpump-IDLStepmotorcontrolpump-Cybotsizeofdispensehead,13,4.2.4Coater(涂胶机）,rpm(转速）andacceleration（加速）Maximumspeed-Upto10000rpmStability-daytodayAcceleration-controllablenumberofstepsReliability-timetoreplacementEBR(Edgebeadremoval)（清边）Method-TopEBRorBottomEBRorTopandbottomEBRProblem-DrippingChemical-Acetone,EGMEA,PGMEA,ETHLY-LACTATE,14,ResistType,NegativeresistPositiveresistG-lineilinereverseimageTAC-topanti-reflectivecoatingBARLI-bottomanti-reflectivecoatingChemicalamplificationresistXrayresist,15,4.3.1Exposure(曝光),Transferapatternfromthemask(reticle)toresistGoal1.CriticalDimensioncontrol(CD)条宽2.Alignment校准-Mis-alignment,runin/out3.Patterndistortion图样变形-Astigmatism4.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胶选择,16,4.3.2Exposure(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,17,4.3.3Exposure(曝光),Contactprint(接触）1.Mostofusefornegativeresistprocess-for5uprocessandcanbepushto3u.2.Positiveresistcanprintsmallerthan3u,anddeepUVcanpushto1u,butveryhighdefect3.Equipment:-CanonPLA501-Cobilt-Kasper-Kinthisfirstprocess,thepattern,orimage,wastransferredfromastoneplate(thewordlithocomesfrom).Thefirstpracticaltwodimensionaldevicepatterningonasiliconwaferwasactuallycarriedoutinthelate1940sattheBellLab.Atthattime,polyvinylcinnamate,developedbyEastmanKodak,wasusedasaresist.However,deviceyieldswerelowbecauseofthepooradhesionofthepolyvinylcinnamatetothesiliconandoxidesurface.TheKodakchemiststhenturnedtoasyntheticrubberbasedmaterial-apartiallycyclizedisopreneandaddedaUVactivesensitizer-abis-aryl-azideintoittocrosslinktherubbermatrixandcreatedanewclassofphotoresistmaterial.Sincetheunexposedareaofthenewmaterialwastheonlypartofthepolymermatrixthatwilldissolveinanorganicsolventandyieldinganegativeimageofthemaskplate,therefore,thenewmaterialwasthenreferredasthenegativeresist.Thecyclizedrubber/bisazideresistwaswidelyusedinthecontactprintingage.However,thecontactmodeofprintingcreatedseverewearofthemaskplateandthedefectdensityofthephotomaskandthewaferwasveryhigh.Theindustrythereforedecidedtoswitchtocontactlessprojectionprintingin1972forproducingthe16kDRAM.Projectionprinting,however,wascarriedoutintheFraunhofferorthesocalledfarfielddiffractionregionandtheaerialimagewasmuchpoorerthanthecontactorproximitymethodofprinting.Inordertopreservethesamequalityofimagestructure,thecontrastoftheimagematerialmustbeincreased.,67,Lithographiclorehasitthatthediazonaphthoquinone/novolakresist(thetermnovolakisderivedfromtheSwedishwordlak,meaninglacquerorresinandprefixedbytheLatinwordnovo,meaningnew)madetheirwayfromtheblueprintpaperindustrytothemicroelectronicthroughfamilyties:atthattimes,theofficesofAzoplate,theAmericanoutletforKalleprintingplate,waslocatedatMurrayHill,NJ,justacrossthestreetfromthefamousBellLabs.ThefatherofatechnicianatAzoplateworkedasatechnicianatBellLabs.ApparentlythefatherhadcomplainedonedayaboutthepoorresolutionqualityofthesolventdevelopedresistsystemusedattheBellLabsandthesonhadboastedthepropertiesoftheAzoplateDNQ/novolakmaterial;anyway,onedaythefathertookabottleofthematerialwithhimtotheBellLabs,andtheageoftheDNQ/novolakresistbegan.ThenewmaterialwasmarketedbyAzoplateunderthetradenameofAZphotoresist.Itwasalwaysreferredasthepositiveresistforapositivetoneofimagewouldbereproducedbythenewmaterial.TheuseofDNQ/novolaksystemincreasedrapidlyaftertheintroductionoftheprojectionlithography.By1980s,theDNQresisthadcompletelysupplantedtheoldnegativeresistastheworkhorseofthesemiconductorindustryinthehigh-endapplications.TheDNQ/novolakresisthasheldswayfor6devicegenerations,fromtheintroductionofthe16KDRAMtothelargescaleproductionofthe64MDRAMin1994to1995.Thesuccessofsuchmaterialwastheindicativeofitsupremeperformanceandpotential.Today,itappearsthatitisnotreallytheresolutionwhichdefinesthelimitoftheDNQ/novolakresistapplication,butratherthelossinthedepthoffocuswiththeeverincreasingNAofthestepper.DeepUVandchemicalamplificationnegativetoneresistslowlyerodethemarketplaceoftheDNQ/novolakresist.Bytheendofthe1990s,theDNQ/novolakresistwasnolongerbeusedinthetechnologicallymostadvancedapplications-theprintingofthecriticallevelsofthe256MDRAM.,68,6.2Future,IntroductionofnanoimprinttechnologyFabricatingmicrostructuresandnanostructureisimportantinmanyfieldsofscienceandtechnology,includingelectronics,datastorage,flexibledisplays,microelectromechanicalsystems,microfluidics,photonicsandbiosensors.Traditionally,opticalorelectronbeamlithographysystemsareusedtoprinttherelevantstructures.However,newprintingmethodssuchasimprintlithographyandsoftlithographyhaverecentlybeenexploredinsomedetailtolowerthecostsoffabricatinglowvolumesofstructureswithverysmallfeaturesandtoincreasetherangeofprintingapplication.Thesoftlithographyschemes,ingeneral,useasofttemplatepatternmadeofsiliconeelastomer,polydimethylsiloxane(PDMS),whichisplacedintocontactwiththesubstrateinavarietyofways,topatternasurfacefilm,totransferamaterial,orfordirectintegrationintothefinalpart,witharangeofinnovativeapplications.ChallengesinthisareaaregenerallyconcernedwiththeinherentlimitationsofthePDMSmaterialincludingresolutionlimitationswhencuringduetodifferencesinthermalexpansionbetweenthemasterandmold;adhesiontocommonmastermaterialslikesilicon;significanttime,aboutanhour,tofabricateamold;elasticityofthemold,whichmayimpactmultilevelalignment;insolubilitywithcommonsolvents;contaminationissuesandincompatibilitywithsomeorganicmaterials.,69,TheimprintmethodsutilizeheatorUVcurableliquidstomoldpatternsontoasubstratefromarigidtemplate.Researchgroupshavedemonstratedsub-100nmresolution,somehavedownto10nm.Imprintprocess;however,donottransfermaterialsfromthetemplatetothesubstratelikethesoftlithographyschemes.Anotherhesitationwiththeimprinttechniqueconcernsthelifetimeofthemasterpattern.Theproblemissimilartothatencounteredinthecontactphotolithography,whereithasbeenfoundthatthedefectfreelifetimeisonlylimitedtolessthan1000passes,despitetheapplicationofcoatingsandlubricants.Thisconcernarisesfromtheimportantrequirementsthatthesubstrate