第二章CMOS制备基本流程.ppt

2.1CMOS制造工艺流程简介,WewilldescribeamodernCMOSprocessflow.Processdescribedhererequires16masksand100processsteps.,第二章CMOS制备基本流程,StagesofICFabrication,InthesimplestCMOStechnologies,weneedtorealizesimplyNMOSandPMOStransistorsforcircuitslikethoseillustratedbelow.,CMOSDigitalGates,反相电路,或非门：同时输入低电平时才能获得高电平输出,PMOSandNMOSwafercrosssectionafterfabrication,2-LevelMetalCMOS,两层互连布线的CMOS,有源器件（MOS、BJT等类似器件），必须在外加适当的偏置电压情况下，器件才能正常工作。,对于MOS管，有源区分为源区和漏区，在进行互联之前，两者没有差别。,ChoosingaSubstrateActiveRegionNandPWellGateTiporExtensionSourceandDrainContactandLocalInterconnectMultilevelMetalization,ProcessingPhases,1mPhotoresist,40nmSiO2,Choosethesubstrate(type,orientation,resistivity,wafersize),Initialprocessing:,-Wafercleaning-thermaloxidation,H2O(40nm,15min.900C)-nitrideLPCVD(低压化学气相沉积)(80nm800C),Substrateselection:-moderatelyhighresistivity(25-50ohm-cm)-(100)orientation-P-type.,80nmSi3N4,ChoosingaSubstrate,Si,(100),PType,2550cm,1stMaskPhotoresistspinningandbaking100C(0.5-1.0m),2.2有源区的形成,Photolithography-Mask#1patternalignmentandUVexposure-Rinseawaynon-patternPR-DryetchtheNitridelayer-PlasmaetchwithFluorineCF4orNF4Plasma-StripPhotoresist(H2SO4或O2plasma),ActiveAreaDefinition(主动区),SiO2,Si3N4,Photoresist,WetOxide(thickSiO2)-H2O(500nm,90min.1000C),StripNitridelayer-Phosophoricacid(磷酸)orplasmaetch，选择性问题,FieldOxideGrowth,-LOCOS:LocalOxidationofSilicon(局部硅氧化工艺),SiO2,Si3N4,薄的SiO2层，厚的Si3N4层，避免鸟喙(birdsbeak)的影响,场区:很厚的氧化层，位于芯片上不做晶体管、电极接触的区域，可以起到隔离晶体管的作用。,Photolithography(套刻)-Mask#2patternalignmentandUVexposure,IonImplantation离子注入-B+ionbombardment,PenetratethinSiO2andfieldSiO2-反型：半导体表面的少数载流子浓度等于体内的多数载流子浓度时，半导体表面开始反型。-150-200keVfor1013cm-2-ImplantationEnergyandtotaldoseadjustedfordepthandconcentration,P-wellFabrication,StripPhotoresist,-Rinseawaynon-patternPR,2.3N阱和P阱的形成,SiO2,Photoresist,IonImplantation-P+ionbombardment,-PenetratethinSiO2andfieldSiO2-300-400keVfor1013cm-2-ImplantationEnergyand,totaldoseadjustedfordepthandconcentration,StripPhotoresist,N-wellFabrication,Photolithography-Mask#3patternalignmentandUVexposure-Rinseawaynon-patternPR,ThermalAnneal(热退火)-Repaircrystallatticestructuredamageduetoimplantation,DryFurnace(N2ambient，防止氧化层生成)-Anneal30min800CorRTA(快速热退火)10sec1000C,-Drive-in4-6hours1000C-1100C,ThermalAnnealandDiffusion,NandPDrive-in(扩散推进)-Thermaldiffusionofdopanttoshallowerthandesireddepth-Drive-inisacumulativeprocess!,Photolithography-Mask#4patternalignmentandUVexposure-Rinseawaynon-patternPR,-B+ionbombardment-50-75keVfor1-51012cm-2,-ImplantationEnergyandtotaldoseadjustedfordepthandconcentration,StripPhotoresist,ThresholdAdjustment,P-typeNMOS,IonImplantation,2.4栅电极的制备,开启电压调整,调整之前P阱的掺杂浓度,调整时的注入剂量,ThresholdAdjustment,N-typePMOS,Photolithography-Mask#5patternalignmentandUVexposure-Rinseawaynon-patternPR,-As+ionbombardment-75-100keVfor1-51012cm-2,-ImplantationEnergyandtotaldoseadjustedfordepthandconcentration,StripPhotoresist,IonImplantation,Removeexistinggateregionoxide,FurnaceSteps-ThermalAnneal,-Oxidegrowth3-5nm-O2ambient-0.5-1hour800C,GateOxideGrowth栅极氧化层生长,-HFetch，具有良好的选择性,-DryFurnace(N2ambient)-30min800C,LPCVDDepositionofSi-Silane硅烷,Amorphousorpolycrystalline,siliconlayerresults,IonImplantation-P+orAs+(N+)implantdopesthepoly(typically51015cm-2),PolysiliconGateDeposition,0.3-0.5um,SiO2,多晶硅薄膜,热分解,Photolithography-Mask#6patternalignmentandUVexposure,PlasmaEtch-Anisotropicetch各向异性蚀刻-Verticaletchratehigh,-Lateraletchratelow,GatePatterning（栅极的图形化）,-Rinseawaynon-patternPR,Clorine(氯)orBromine(溴)basedforSiO2selectivity,目标：,NMOS器件中的N-注入区,PMOS器件中的P-注入区,多晶硅栅的两侧形成侧壁隔离层的薄氧化层,2.5前端或延伸区(LDD)的形成,LDD:,LightlyDopedDrain(轻掺杂漏)ReduceshortchanneleffectsduetogatevoltagemagnitudesandelectricfieldsSourceandDrainmustbelayeredasNMOS:N+N-PorPMOS:P+P-N,Extension(LDD)FormationNMOS,Photolithography-Mask#7patternalignmentandUVexposure-Rinseawaynon-patternPR,-P+ionbombardment-50keVfor51013cm-2,StripPhotoresist,IonImplantation,PhotolithographyMask#8patternalignment,andUVexposureRinseawaynon-patternPRIonImplantationB+ionbombardment50keVfor51013cm-2,StripPhotoresist,Extension(LDD)FormationPMOS,SiO2隔离介质层,CVDorLPCVDDepositionofSiO2,SilaneandOxygen,Or,0.5um,Providesspacingbetweengateandsource-drain.,SiO2SpacerDeposition,Photolithography,Mask#6oversizedpatternalignmentandUVexposureRinseawaynon-patternPR,VerticaletchratehighLateraletchratelow,StripPhotoresist,AnisotropicSpacerEtch,PlasmaEtchAnisotropicetch,Flourinebased,ScreenOxideGrowthThinSiO2layer10nmtoscattertheimplantedions,Photolithography,Mask#9patternalignmentandUVexposureRinseawaynon-patternPR,IonImplantationAs+ionbombardment75keVfor2-41015cm-2,StripPhotoresist,NMOSSourceandDrainImplant,2.6源漏区的形成,Arsenic,Reducechanneling,Photolithography,Mask#10patternalignmentandUVexposureRinseawaynon-patternPR,IonImplantationB+ionbombardment5-10keVfor1-31015cm-2,StripPhotoresist,PMOSSourceandDrainImplant,N+andP+Drive-in,ThermaldiffusionofdopanttoshallowerthandesireddepthDrive-inisacumulativeprocess!,DryFurnace(N2ambient)Anneal30min900CorRTA60sec1000C-1050C,TransientEnhancedDiffusion(TED瞬态增强扩散)Higherthannormaldiffusivityduetocrystaldamage,ThermalAnnealing,ThermalAnnealRepaircrystallatticestructuredamageduetoimplantation,2.7接触与局部互联的形成,ContactsandInterconnects,TitaniumsputteringlocalcontactsConformalCoatwithSiO2PlanarizationTungstenPlugviasAluminumMetalDepositionRepeatCoatPlanarizePlugMetaldeposition,HFetchtoremovethinSiO2Removescreenoxidefromdrain,sourceandploygateregionsDip(浸)forafewsecondswithHF,ContactOpenings,LDDandSidewallstructureNMOS:LateralN+N-PN-N+PMOS:LateralP+P-NP-P+,TitaniumDeposition,Tiisdepositedbysputtering(typically100nm).TitargethitwithAr+ionsinavacuumchamber,TheTiisreactedinanN2ambient,FormsTiSi2andTiN(typically1min600-700C).,TiSi2hasexcellentcontactcharacteristics(良好的导体)TiNdoesnot,butcanbeusedforlocalwiring(导电材料，短程互连布线),TiSi2,TiN,PhotolithographyMask#11patternalignmentandUVexposureRinseawaynon-patternPR,TiNetchNH4OH:H2O2:H2O(1:1:5),StripPhotoresist,LocalTiNInterconnect,ThermalTreatinAr减小电阻1min800C,用TiN作为局部互连引线,ConformallayerofSiO2isdepositedbyCVDorLPCVD(typically1m),PSG(磷硅玻璃)orBPSG(硼磷硅玻璃)磷：Surfacepassivation(表面钝化)硼：Glassreflowforpartialplanarization(加热，令表面平整),ChemicalMechanicalPolishing(CMP化学机械抛光),Planarizethewafersurface平坦化,PolishwithhighpHsilicaslurry(硅酸盐研磨浆料),ConformalCoatandPlanarize,2.8多层金属互连的形成,SiO2,表面不平坦带来很多问题,两种解决方法：,PhotolithographyMask#12patternalignmentandUVexposure,Rinseawaynon-patternPR,SiO2plasmaetchAnisotropicetch,StripPhotoresist,Viasto1stMetal,选择第一层金属布线需要与下层器件结构形成连接的接触孔位置,接触孔形成,ViaDepositionTungstenPlugs(插头),TiNorTi/TiNbarrierlayer粘结层/阻挡层，增强金属与SiO2的粘附性,SputteringorCVD(fewtensofnm),CVDTungsten(W),ChemicalMechanicalPolishing(CMP),PlanarizethewafersurfacePolishwithhighpHsilicaslurry,EtchContactHoles(接触孔的蚀刻)orLineTrenches(沟道)Filletchedregions(蚀刻区的填充)Planarize(平坦化)CMPprocessAlsoremovesmaterialthat“overflowedholesortrenches”,DamasceneProcess大马士革镶嵌工艺,大马士革镶嵌工艺包括：,StripPhotoresist,Metal#1Deposition,第一层金属布线,PhotolithographyMask#13patternalignmentandUVexposureRinseawaynon-patternPR,Anisotropicplasmaetch,SiO2,Al,光刻胶,SputteredAluminumAlwithsmallamountsofSiandCu-Cureduceselectromigration避免电迁移现象带来的断路-Si降低接触电阻,MultipleMetalLayers,DepositsOxideLayerCMPPhotolithographyMask#14EtchViasDepositviamaterialCMPDepositNextMetalLayerPhotolithographyMask#15,FinalpassivationlayerofSi3N4isdepositedbyPECVDandpatternedwithMask#16.防止Na+、K+污染和封装中的机械损伤,Finalannealandalloyinforminggas(10%H2inN2)30min400-450C形成良好的