SMT-17_Doping_CD

©2001byPrenticeHallSemiconductorManufacturingTechnologybyMichaelQuirkandJulianSerdaSemiconductorManufacturingTechnologyMichaelQuirk&JulianSerda©October2001byPrenticeHallChapter17DopingProcesses©2001byPrenticeHallSemiconductorManufacturingTechnologybyMichaelQuirkandJulianSerdaObjectivesAfterstudyingthematerialinthischapter,youwillbeableto:1.Explainthepurposeandapplicationsfordopinginwaferfabrication.2.Discusstheprinciplesandprocessofdopantdiffusion.3.Provideanoverviewofionimplantation,includingitsadvantagesanddisadvantages.4.Discusstheimportanceofdoseandrangeinionimplant.5.Listanddescribethefivemajorsubsystemsforanionimplanter.6.Explainannealingandchannelinginionimplantation.7.Describedifferentapplicationsofionimplantation.©2001byPrenticeHallSemiconductorManufacturingTechnologybyMichaelQuirkandJulianSerdaCommonDopantsUsedinSemiconductorManufacturingAcceptorDopantGroupIIIA(P-Type)SemiconductorGroupIVADonorDopantGroupVA(N-Type)ElementAtomicNumberElementAtomicNumberElementAtomicNumberBoron(B)5Carbon6Nitrogen7Aluminum13Silicon(Si)14Phosphorus(P)15Gallium31Germanium32Arsenic(As)33Indium49Tin50Antimony51Table17.1©2001byPrenticeHallSemiconductorManufacturingTechnologybyMichaelQuirkandJulianSerdaCMOSStructurewithDopedRegionsn-channelTransistorp-channelTransistorLIoxidep–epitaxiallayerp+siliconsubstrateSTISTISTIn+p+p-welln-wellp+p–p+p–p+n+n–n+n–n+ABCEFDGHKLIJMNOn+nn++p+pp++Figure17.1©2001byPrenticeHallSemiconductorManufacturingTechnologybyMichaelQuirkandJulianSerdaCommonDopantProcessesinCMOSFabricationProcessStepDopantMethodA.p+SiliconSubstrateBDiffusionB.p-EpitaxialLayerBDiffusionC.Retrograden-WellPIonImplantD.Retrogradep-wellBIonImplantE.p-ChannelPunchthroughPIonImplantF.p-ChannelThresholdVoltage(VT)AdjustPIonImplantG.p-ChannelPunchthroughBIonImplantH.p-ChannelVTAdjustBIonImplantI.n-ChannelLightlyDopedDrain(LDD)AsIonImplantJ.n-ChannelSource/Drain(S/D)AsIonImplantK.p-ChannelLDDBF2IonImplantL.p-ChannelS/DBF2IonImplantM.SiliconSiIonImplantN.DopedPolysiliconPorBIonImplantorDiffusionO.DopedSiO2PorBIonImplantorDiffusionTable17.2©2001byPrenticeHallSemiconductorManufacturingTechnologybyMichaelQuirkandJulianSerdaIonImplantinProcessFlowUsedwithpermissionfromLanceKinney,AMDImplantDiffusionTest/SortEtchPolishPhotoCompletedwaferUnpatternedwaferWaferstartThinFilmsWaferfabrication(front-end)Hardmask(oxideornitride)AnnealafterimplantPhotoresistmaskFigure17.2©2001byPrenticeHallSemiconductorManufacturingTechnologybyMichaelQuirkandJulianSerdaDopedRegioninaSiliconWaferOxideOxidep+SiliconsubstrateDopantgasNDiffusedregionFigure17.3©2001byPrenticeHallSemiconductorManufacturingTechnologybyMichaelQuirkandJulianSerdaDiffusion•DiffusionPrinciples–ThreeSteps•Predeposition•Drive-in•Activation–DopantMovement–SolidSolubility–LateralDiffusion•DiffusionProcess–WaferCleaning–DopantSources©2001byPrenticeHallSemiconductorManufacturingTechnologybyMichaelQuirkandJulianSerdaDopantDiffusioninSiliconDisplacedsiliconatomininterstitialsiteSiSiSiSiSiSiSiSiSic)MechanicalinterstitialdisplacementSiSiSiSiSiSiSiSiSia)Siliconlatticestructureb)SubstitutionaldiffusionSiSiSiSiSiSiSiSiVacancyDopantd)InterstitialdiffusionSiSiSiSiSiSiSiSiSiDopantininterstitialsiteFigure17.4©2001byPrenticeHallSemiconductorManufacturingTechnologybyMichaelQuirkandJulianSerdaSolidSolubilityLimitsinSiliconat1100°CDopantSolubilityLimit(atoms/cm3)Arsenic(As)1.7x1021Phosphorus(P)1.1x1021Boron(B)2.2x1020Antimony(Sb)5.0x1019Aluminum(Al)1.8x1019Table17.3©2001byPrenticeHallSemiconductorManufacturingTechnologybyMichaelQuirkandJulianSerdaDiffusionProcessEightStepsforSuccessfulDiffusion:1.Runqualificationtesttoensurethetoolmeetsproductionqualitycriteria.2.Verifywaferpropertieswithalotcontrolsystem.3.Downloadtheprocessrecipewiththedesireddiffusionparameters.4.Setupthefurnace,includingatemperatureprofile.5.CleanthewafersanddipinHFtoremovenativeoxide.6.Performpredeposition:loadwafersintothedepositionfurnaceanddiffusethedopant.7.Performdrive-in:increasefurnacetemperaturetodrive-inandactivatethedopantbonds,thenunloadthewafers.8.Measure,evaluateandrecordjunctiondepthandsheetresistivity.©2001byPrenticeHallSemiconductorManufacturingTechnologybyMichaelQuirkandJulianSerdaTypicalDopantSourcesforDiffusionDopantFormulaofSourceChemicalNameArsenic(As)AsH3Arsine(gas)Phosphorus(P)PH3Phosphine(gas)Phosphorus(P)POCl3Phosphorusoxychloride(liquid)Boron(B)B2H6Diborane(gas)Boron(B)BF3Borontri-fluoride(gas)Boron(B)BBr3Borontri-bromide(liquid)Antimony(Sb)SbCl5Antimonypentachloride(solid)SEMATECH“DiffusionProcesses,”FurnaceProcessesandRelatedTopics,(Austin,TX:SEMATECH,1994),P.7.Table17.4©2001byPrenticeHallSemiconductorManufacturingTechnologybyMichaelQuirkandJulianSerdaIonImplantation•Overview–ControllingDopantConcentration–AdvantagesofIonImplant–DisadvantagesofIonImplant•IonImplantParameters–Dose–Range©2001byPrenticeHallSemiconductorManufacturingTechnologybyMichaelQuirkandJulianSerdaControllingDopantConcentrationandDeptha)Lowdopantconcentration(n–,p–)andshallowjunction(xj)MaskMaskSiliconsubstratexjLowenergyLowdoseFastscanspeed