工艺技术_wet工艺介绍

WETProcessIntroduction PurposeofWetCleaningProcess Throughtoaseriesofprocessestomakethewafersfreefromparticles organiccontaminations metalcontamination surfacemicroroughnessandnativeoxideusingsomekindsofchemicalsincludingDIW PurposeofWetCleaningProcess ForEtchingprocessOxideremove Nitrideremove Photoresist polymerremove ForCleaningprocessFreeofparticles Freeofmetalion Freeoforganic Freeofmicro roughness Freeofnativeoxide WetCleaning Pre treatment WetCleaning Post treatment ResistRemoval Diffusion CVD PVD Lithography Etching Doping WaferIn WaferOut ICProcessing WetProcess 1 FEOLpost ashclean35 typicalSPM trendistointegrateresiststripingandcleaning 2 Pre diffusionclean30 RCAclean trendistousedilutechemistriestoreducecost improveequipmentreliabilityandprocessperformance 3 BEOLpost etchclean20 issueswithtechnical cost environment trendistousesinglewaferdryclean4 Others PostCMPandspecialcleaning 15 SC1basedcleaning ChemicalsInvolved Wetbench PurposeofPre cleanistoremovethelastunwantedoxidelayerandpreparesurfacefreeofmetalliccontaminantsandgoodPCfornextoxidation Pre diffusionclean RCAclean SiO2 s 6HF l H2SiF6 l 2H2O l Theetchrate orreactionrateofHFwithoxide canbeslowedbyaddingmorewaterandlowerstheconcentrationofHF HFwilletchBPSG Oxide Nit Si H2O HF100 1 50 1 49 Function RemoveOxide SiO2 Mechanism ReactswithOxideandformasolvablebyproduct OxideEtchHF EtchingoffnativeoxideleavinghydrophobicSisurface repelsH2O thatispronetoH2OmarkAsamethodtopassivatesurface H2O2 SC1 SC2lastisused AftercleaningHFonSi theSiwaferhasH2SiF6 itischargedupwithSiF62 ions thishashighaffinitytoattractdefects duetostrongpolarity WhatisH2Omark ItissomeH2OstainwhichoxidisestheSisurface ItcanalsobeaconcentrationofH2Ocontaminants H2Oattractedarea easytocreateH2Omark ox ox Siwafer Whatistheimpactofwatermark Watermarkcancauseproblemswithadhesionoffilms contactresistance non uniformitybetweenconductinglayers blocketch gateoxidedefects Howtopreventit Treatthewafersurfacewitheg H2O2 SC1 SC2 someoxidationeffects toensurehydrophilicsurfacethroughout EnsuredryersperformanceVaporJetdryerLowpressureDryerSpinDryerMicroMistDryer DIwaterisDe ionizedwater WaterRinse DIWater DIWtankisforrinsingwaferascleanaspossiblebeforegoingintothenextchemicaltanktopreventcross contaminationorbeforeleavingthehood DIWcanoverfloworquickdumprinse QDR OverflowisverystableflowofDIWandgivesgoodPCcontrol Itmakesuseofdiffusionanddilution QDR ontheotherhandmakesuseofextradragforcewhenDIWdump itisfastatremovingacidtrace butsincethereismoreagitationinthetank itmayresultinhigherPC ControloftheDIWtankandsurroundingcleanlinessisimportant DIWtankoverflowsatalltimeswithby passflowtopreventbacteria BacteriawillresultinPC metalliccontamination DIWTank DIWcanbehotorcold dependsonpreviousandnexttanks HotChemicalwillbefollowedbyHotDIW ColdDIW thisistopreventthermalshock Forhighviscositychemical HDIWrinsewillimprovesolubilityofthechemical thusimprovethediffusionofchemicaltobulkofDIW thisimprovestherinseefficiency ThereisalsotheDIWMegasonicTank overfloworwithquickdumprinse TheextraMegasonicpowerhelpsparticlereductionandimprovesrinsingefficiencyespeciallyforviscouschemical DIWTank DIWflow rate ProcessTime DumpCycle ProcessTimeforeachsequence MegasonicOnSequence CriticalParameters 30C NH4OH H2O2 H2O 1 2 50 Function Particleremoval LightpolymerremovalMechanism oxidationandelectricalrepulsion Oxidation Dissolution Surfaceetching Electricalrepulsion Oxidationmechanism Electricalrepulsionmechanism ParticlecleanSC1 Standardclean1 SC1withMegasonic Transducer Transducer Transducer Partialwetting Solventdiffusingatinterface Totalwetting Floatingfree Benefit enhancetheparticleremoverate Drawback H2O2willbereducedduringoperation whichcausesurfaceroughness ThemechanismproducingtheroughsurfaceistheNH4OHactsastheetchantoftheoxidewhileH2O2actsastheoxidant SurfaceMicro roughness Si H2SiO42 H3SiO4 HSiO43 etc V1 V2 HO2 OH Path 1 Path 2 OH V3 V1 k1 HO2 3k1 1 2x1014 65C V2 k2 OH k2 5970 65C V3 k3 OH 2k3 2 0 x109 65C Path 1 Path 2 SiSubstrate Methodsofreducingthemicroroughnesscanbesummarizedas ReducetheproportionofNH4OH theetchant ReducethetemperatureofthebathReducethecleaningtimeConventionalSC1 1 1 5 70 80C NH4OHevaporate44 at70 H2O2decompositionisastrongfunctionofmetalioncontent SC1BathLifeProblems HeaterBurnt InlineheaterismadeofQuartzandSC1etchesSi thusinlineheaterhaslifetime Ifburntandleaking therecanbemetalcontaminationslikeALandFe NH4OHandH2O2willdegradeandcausebubbling mayresultinstreakdefectsonthewafer CommonIssueswithSC1 Togetridofbubbles Tiltwafertofacebackm c Slightagitationofwaferstoreleasebubblefromwafersurfacem c Bubblecollapser degaser CommonIssueswithSC1 30C HCl H2O2 H2OFunction IonicandMetallicContaminationRemoval MetalliccleanSC2 Standardclean2 Mechanism HCLreactswithmetaltoformasolublesaltwhichisremovedfromwafersurfacebydissolvinginH2O AsfarasH2O2 itpassivitytheactivesurface HCl H2O2arenoteasytobeproducedtobeultracleanandassuch thechemicalitselfhavesomemetallic WhendilutedSC2isused metallicfromwafercanstillberemovedandthechemicalalsohaslessmetallictodepositonthewafer Thisisthebestscenario Note Cleanupisnotalwaysremovingdefects contaminants itdependson who isdirtier Diffusionprinciple movementofsolutesfromhigherconcentrationtolowerconcentrationuntilequilibrium ProblemwithSC2 Dryer IsopropylAlcohol IPA Function removeswaterfromwafersMechanism Alcoholvaporsdisplacewaterfromsurface Thealcoholevaporatesmoreeasilythanwater Itleavesadrysurface Cleaning HF H3PO4 PhosphoricAcid Function AAnitridestripaftergrowingisolationoxide NitrideRemove NitrideetchrateinH3PO4At1600C H3PO4is87 atboilingpoint Originalchemicalconcentration 86 Asthechemicalheatsup DIWspikesintomaintainchemical boilsat1600C optimaletchrate Mayresultinwafercrossslotduetowatersuperboil DIWspikingpositionandcontrolarecriticalforoptimalprocess NitrideRemove Mechanism Si3N4 6H2O 3SiO2 4NH3 H3PO4ascatalyst ERA min SiConc ppm Particle ml 0 2um SiN SiO2 Particle NitrideRemove WhentheSiliconcontentisveryhigh oxideetchratedecreases Siliconmayevenre depositonwaferandtrapsomeH3PO4 IfthisPhosisimplanted drivenintothewafer itwillgiveextra n typewhichmayleadtoleakyFieldOxideandpoorGOI Inordertostabilizetheetchlossofoxide forthe2H3PO4tankprocesstime Tank1timeissettoremovealltheNitridewhileTank2takescareoftheoveretch Asaresult theTank2oxideetchrateismorestablewhichleadstobetteroxideremainscontrol Oxynitride oxide AASiN 100APadOxide HFdip AASiN 100APadOxide HPO1 100APadOxide HPO2 AASiNStripProcessforCM71DRAM PadOxideRemained HPOlifetimedependent RecipeNLH240AHPO2550ASC1M SPM SulfuricPeroxideMixture 98 H2SO4 30 H2O2 5 1 125CCaro sacid SPM PiranhaFunction Photo resiststrippingOrganiccontaminationremovalMechanism H2SO4 H2O2 HO SO2 O OH H2OHO SO2 O OH CH2 n CO2 H2O UsehotQDR QuickDumpRinse withmega sonictorinseoffviscousH2SO4onwafers RecipeforPRStrip NDH10APRRMM DHF 100 1 15 SPM5 SPM5 HQDR withMega NPRRM SPM5 SPM5 HQDR w oMega BOE BufferedOxideEtch 23C Mixtureof40 NH4Fand49 HFSMICdefineMB BOE 10 1 LB BOE 130 1 7 DB BOE 200 1 SurfactantsareoftenaddedtoimprovewettingBenefitcomparedtoDHF 1 Lowselectivityoxideetch forDRAMcontactpre clean2 Preventphotoresistliftoff forKV DualgateprocessForBOEetchwithPRonwafers S DorMarangoniisusedfordrying SiO2 BPSGetchingmechanism SiO2ismainlyetchedbyHF2 SiO2 2HF2 2H3O SiF4 4H2OSiF4 2HF H2SiF6 inHFsolution SiF4 2NH4F NH4 2SiF6 inBOEsolution BPSGismainlyetchedbyHFB2O3 6HF 2BF3 3H2O BPSG SiO2etchingselectivitycontrol NH4F BPSG SiO2 NH4F NH4 F HF H F K1 H F HF 0 00068HF F HF2 K2 HF F HF2 0 193 NH4Fconcentration mol Kg Etchrateat25C A min DHFpre cleanforPolydep OxideA OxideB OxideC ACT940isusedtoremovePlasmacuredphotoresistHardcrestofside wallpolymerCl ionstrappedintheside wallpolymer photoresistO3 plasmaAshing PRS PRS photoresiststrip PSR Poststripperrinse DIW dryer PlasmaAshing removehard curedphotoresist 95 99 PRS removeside wallpolymerbyreductiveetchwithNH2OH HDA HydroxylAmine PRS ACT 690C ACT 940 EKC 265 EKC 270 etc PSR neutralizeamines minimizeOHinducedcorrosioncausingbyunevenmicro etchinDIwaterrinse PSR NMP IPA etc PRS ACT940Solvent 1 Metaletchpostclean VIAEtchpostclean OtherWetEtchChemicalsinSMICSC1 NH4OH H2O2 H2O 1 1 1 24C30 40min TiSelectiveEtchSC1 NH4OH H2O2 H2O 1 1 5 50C5min CoselectiveetchM2 H3PO4 HNO3 CH3COOH 70 2 12 75C20min49 HF HF 20 1 OxidereclaimPolyetch HNO3 HF 6 1 23C PolyreclaimSC1 NH4OH H2O2 H2O 1 1 5 50C WMetalreclaimSPM H2SO4 H2O2 5 1 125C Al Cu Ti TiNMetalreclaim DryerIntroduction DryerisusedtoensurethattheDIWonthewaferisnotevaporatedbuteitherdisplacedorphysicallyremoved PresentlytherearefollowingtypesofdryersinFab7 Spindryer S D VJD VaporJetDryer LPD Lowpressuredryer MMD MicroMistDryer SpinDryer On CentreType Off CentreType CriticalParameters TransferTime On centrefaster RampupspeedMaxspeedProcessTimeExhaustIonizer StandardVapourDryer EithermadeofQuartzorStainlessSteel IPACondensate DrainPlate HeatTransferAdhesive HeaterBlock IPA CriticalParameters WafertransfertimefromF Rtobaseofdryer78oCafter30sec IPADIW 0 5 HeaterTempHeatTransferAdhesionF RtoresistivityRobotarmup downV D mayresultinPCIPAlevelsensorbox mayresultinPC PrincipleofMarangoni Drying Operatingtemperatuer RTProcesstime7 10minIPAconsumptionappr 4 10ml 50Wafers6 8 DIwater run80 100lNitrogen run120 180lIPApeakconcentrationinDIwater 30ppm DiffusionofIPAinWaterIPAConcentrationA B MeniscusGeometry IPADecreasesSurfaceTensionSurfaceTensionA BMARANGONI Force LiquidFlowfromAtoBWithdrawWaferoutofWaterResul