集成电路专业英语 课件 10 Wafer Fabrication

10WaferFabrication:TheFoundationofIntegratedCircuitManufacturingPartⅣIntegratedCircuitManufacturingProcessIntroduction:TheHeartofMicroelectronicsSemiconductorwaferfabricationisthefundamentalprocessinmicroelectronics.Itservesasthecornerstoneofmodernintegratedcircuit(IC)production.Fromrawmaterialstopolishedsiliconwafers:properties,purification,crystalgrowth,andwaferprocessing.WhySilicon？Abundant&cheap:derivedfromsilicondioxide(SiO₂)insandandquartz.Idealsemiconductorwithcontrollableconductivityandexcellentdopingcontrol.Formsasuperiornativeoxide(SiO₂)thatisstable,high-quality,andpreciselycontrollable.Materialstability:durableandnon-toxiccomparedwithGaAs;mustbeultra-puresinglecrystal.OtherFormsofSiliconSingle-CrystalSilicon:perfectlattice;foundationforalladvancedICwafers.PolycrystallineSilicon:manysmallcrystals;usedforgates,maskinglayers,andinterconnects.AmorphousSilicon:disorderedstructure;mainlyforsolarcellsanddisplays,notmainstreamICs.Step1:ProductionofRaw(Metallurgical-Grade)SiliconSourcematerial:Quartzite(SiO₂).Carbothermicreductioninanarcfurnaceat~1460°C.Reaction:SiO₂+2C→Si+2CO.Output:Metallurgical-GradeSilicon(98–99%purity),unsuitablefordirectICuse.Step2:PurificationtoElectronicGradeGoal:Electronic-GradeSiliconwith99.999999999%purity.Keyintermediate:Trichlorosilane(SiHCl₃).Multi-stepprocess:grinding,HClreaction,distillation,andpurification.Step3:DepositionofElectronic-GradeSilicon(EGS)ChemicalVaporDeposition(CVD)inaSiemensreactor.Reaction:SiHCl₃+H₂→Si+3HClat~1100°C.Producesultra-purepolycrystallinesiliconrodsforcrystalgrowth.SingleCrystalGrowth–Czochralski(CZ)MethodDominantmethodforover90%ofsiliconwafers.MeltedEGSinquartzcruciblewithaseedcrystalpulledupwardwhilerotating.Produceslargecylindricalsingle-crystalingotswithcontrolleddiameter.CZMethod:ProsandConsAdvantages:lowercostandverylargewaferdiameters(300mm+).Disadvantages:oxygencontaminationfromcrucible.Dopantconcentrationgradientalongingotlength.SingleCrystalGrowth–Float-Zone(FZ)MethodUsedforhigh-purityapplicationssuchaspowerdevices.Localizedmoltenzonepassesalongapolycrystallinerod.Nocruciblecontact,resultinginextremelypuresinglecrystals.FZMethod:ProsandConsAdvantages:extremelyhighpurityanduniformresistivity.Disadvantages:highercostanddifficultygrowinglargediameters.Dopingachievedviagasesinthegrowthchamber.FromIngottoWafer:InitialProcessingIngotisgroundtoprecise,uniformdiameter.Orientationflatsindicatecrystalorientationanddopingtype.Notchesreplaceflatsforwafers≥200mmtosavesurfacearea.WaferFabricationProcessFlowSawingLappingBeveling(EdgeRounding)EtchingPolishingStep1:SawingSlicesingotintothinwafers.Modernmulti-wiresawusesthinwiresandslurry.Cutshundredsofwaferssimultaneouslywithreducedkerfloss.Step2:Lapping&Step3:BevelingLappingremovessawdamageandimprovesflatness.Bevelingroundswaferedgestopreventchipping.Improvesyieldbyreducingparticlecontamination.Step4:Etching&Step5:PolishingWetchemicaletchingremovessubsurfacedefects.Chemical-mechanicalpolishingcreatesmirror-likesurface.Finalsurfaceroughnesslessthan3nanometers.TheEvolutionofWaferSizeLargerwafersreducecostperchip.Industrystandardtoday:300mmwafers.450mmresearchedbutlargelyshelvedduetocost.SummarySilicon’spropertiesmakeitide