半導體工藝基礎第三章氧化半導體工藝基礎第三章氧化1Oxidation氧化簡介氧化膜的應用氧化機理氧化工藝氧化設備RTO快速熱氧化Oxidation氧化簡介2簡介硅與O2直接反應可得；SiO2性能穩(wěn)定；氧化工藝在半導體制造中廣泛使用Si+O2→SiO2氧化層簡介簡介硅與O2直接反應可得；Si+O2→SiO2氧化層3Oxidation氧化層簡介SiliconOxidation氧化層簡介Silicon4氧化膜的應用摻雜阻擋層表面鈍化(保護)–Screenoxide,padoxide,barrieroxide隔離層–FieldoxideandLOCOS柵氧化層氧化層應用氧化膜的應用摻雜阻擋層氧化層應用5摻雜阻擋氧化層MuchlowerBandPdiffusionratesinSiO2thanthatinSiSiO2canbeusedasdiffusionmask氧化層應用摻雜阻擋氧化層MuchlowerBandPdiff6表面鈍化(保護)氧化層PadOxide襯墊氧化層,ScreenOxide屏蔽氧化層SacrificialOxide犧牲氧化層,BarrierOxide阻擋氧化層Normallythinoxidelayer(~150?)toprotectsilicondefectsfromcontaminationandover-stress.氧化層應用表面鈍化(保護)氧化層PadOxide襯墊氧化層,Scr7Steamoxidationhashighergrowthratethandryoxidation被淺的管溝(STI)所取代DryOxidationSystem–Lesssteepsidewall側墻不很陡峭BlanketFieldOxideIsolationDryOxidationSystemBlanketfieldoxideSiO2canbeusedasdiffusionmaskSiO2canbeusedasdiffusionmaskComparewithblanketfieldoxideHighPressureOxidationH2SO4:H2O2orNH3OH:H2O2followedbyDIH2Orinse.Disadvantage缺點–FieldoxideandLOCOS犧牲氧化層SacrificialOxideFaster,higherthroughput通常，摻雜濃度越高，氧化層生長速率越高；氧化：雜質堆積和耗盡效應H2SO4:H2O2orNH3OH:H2O2followedbyDIH2Orinse.Localoxidationofsilicon(LOCOS)ScreenOxide氧化層應用Steamoxidationhashighergro8PadandBarrierOxidesinSTIProcess氧化層應用USG:UndopedSilicateGlass未摻雜硅酸鹽玻璃PadandBarrierOxidesinSTI9Application,PadOxideRelievestrongtensilestressofthenitridePreventstressinducedsilicondefects氧化層應用Application,PadOxideRelieve10犧牲氧化層SacrificialOxideDefectsremovalfromsiliconsurface氧化層應用犧牲氧化層SacrificialOxideDefect11器件隔離氧化層臨近器件的絕緣隔離BlanketfieldoxideLocaloxidationofsilicon(LOCOS)Thickoxide,usually3,000to10,000?氧化層應用器件隔離氧化層臨近器件的絕緣隔離氧化層應用12BlanketFieldOxideIsolation氧化層應用BlanketFieldOxideIsolation氧13LOCOSProcess氧化層應用LOCOSProcess氧化層應用14LOCOSComparewithblanketfieldoxide–Betterisolation更好的隔離–Lowerstepheight更低臺階高度–Lesssteepsidewall側墻不很陡峭Disadvantage缺點–roughsurfacetopography粗糙的表面形貌–Bird’sbeak鳥嘴被淺的管溝(STI)所取代氧化層應用LOCOSComparewithblanketfiel15柵氧化層Gateoxide:thinnestandmostcriticallayerCapacitordielectric氧化層應用柵氧化層Gateoxide:thinnestandm16氧化膜(層)應用名稱應用厚度說明自然氧化層不希望的15-20A屏蔽氧化層注入隔離，減小損傷~200A熱生長摻雜阻擋層摻雜掩蔽400-1200A選擇性擴散場氧化層和LOCOS器件隔離3000-5000A濕氧氧化襯墊氧化層為Si3N4提供應力減小100-200A熱生長很薄犧牲氧化層去除缺陷<1000A熱氧化柵氧化層用作MOS管柵介質30-120A干氧氧化阻擋氧化層防止STI工藝中的污染100-200A氧化層應用氧化膜(層)應用名稱應用厚度說明自然氧化層不希望的15-2017SiliconDioxideGrownonImproperly

CleanedSiliconSurfaceSiliconDioxideGrownonImpro18表面未清洗硅片的熱氧化層熱氧化生長的SiO2層是無定形的SiO2分子間趨于交聯(lián)形成晶體未清洗硅片表面的缺陷和微粒會成為SiO2的成核點這種SiO2層的阻擋作用很差氧化前需要清洗硅片表面表面未清洗硅片的熱氧化層熱氧化生長的SiO2層是無定形的19氧化前圓片清洗顆粒有機粘污無機粘污本征氧化層氧化前圓片清洗顆粒20RCA清洗DevelopedbyKernandPuotinenin1960atRCAMostcommonlyusedcleanprocessesinICfabs(1號液)－NH4OH:H2O2:H2O

with1:1:5to1:2:8ratioat70to80℃toremoveorganic.(2號液)--HCl:H2O2:H2O

with1:1:6to1:2:8ratioat70to80℃toremoveinorganiccontaminates，DIwaterrinseHFdiporHFvaporetchtoremovenativeoxide.RCA清洗DevelopedbyKernandPuo21–FieldoxideandLOCOSBubblerSystem表面未清洗硅片的熱氧化層氧化薄膜越厚，生長速率越低Pre-oxidationWaferCleanNativeOxideRemovalScreenOxideB/A為線性速率常數；Si+O2→SiO2–FieldoxideandLOCOSSi+2H2O→SiO2+2H2BoilerSystemHighpurityN2asprocesspurgegasHClisusedtoreducemobileioncontaminationLowergradeN2asidlepurgegasPyrogenicSteamSystemLocaloxidationofsilicon(LOCOS)HighpurityN2asprocesspurgegasLowergradeN2asidlepurgegas被淺的管溝(STI)所取代SiO2canbeusedasdiffusionmask在合成水汽中的氧化速率Pre-oxidationWaferCleanParticulateRemovalHighpuritydeionized(DI)waterorH2SO4:H2O2followedbyDIH2Orinse.高壓清洗或者放在清洗液中加熱漂洗，最后烘干Highpressurescruborimmersioninheateddunktankfollowedbyrinse,spindryand/ordrybake(100to125°C).–FieldoxideandLOCOSPre-oxi22被氧化的硅片上有機物的清除強氧化劑清除有機污垢H2SO4:H2O2orNH3OH:H2O2followedbyDIH2Orinse.Highpressurescruborimmersioninheateddunktankfollowedbyrinse,spindryand/ordrybake(100to125°C).被氧化的硅片上有機物的清除強氧化劑清除有機污垢23無機物的清洗先用HCl:H2O液體浸泡再在大的玻璃杯中浸泡清洗Immersionindunktankfollowedbyrinse,spindryand/ordrybake(100to125℃)無機物的清洗先用HCl:H2O液體浸泡24Pre-oxidationWaferCleanNativeOxideRemovalHF:H2OImmersionindunktankorsinglewafervaporetcherfollowedbyrinse,spindryand/ordrybake(100to125℃)Pre-oxidationWaferCleanNati25OxidationMechanismSi+O2→SiO2O來源于提供的氧氣Si來源于襯底硅圓片O通過表面已有的氧化層向內擴散并與Si反應生長SiO2氧化薄膜越厚，生長速率越低干氧氧化（DryOxidation）OxidationMechanismSi+O2→SiO2干26OxideGrowthRateRegimeB/A為線性速率常數；B為拋物線速率常數OxideGrowthRateRegimeB/A為線性27<100>SiliconDryOxidation<100>SiliconDryOxidation28BlanketFieldOxideIsolation氧化速率對溫度很敏感，指數規(guī)律HigherdielectricstrengthB/A為線性速率常數；Highpressurescruborimmersioninheateddunktankfollowedbyrinse,spindryand/ordrybake(100to125°C).AthightemperatureH2OisdissociatedtoHandH-OThickoxide,usually3,000to10,000?RTOwillbeusedtoachievethedevicerequirement.Disadvantage缺點Reducingoxidationtemperature:1amt.BubblerSystem再在大的玻璃杯中浸泡清洗對于更厚的氧化層，O需要更多的時間擴散過氧化層與襯底硅發(fā)生反應Pre-oxidationWaferCleanParticulateRemoval被淺的管溝(STI)所取代RTOwillbeusedtoachievethedevicerequirement.–Lowerstepheight更低臺階高度HClisusedtoremovemobileionsforgateoxidationNormallythinoxidelayer(~150?)toprotectsilicondefectsfromcontaminationandover-stress.Relievestrongtensilestressofthenitride水汽氧化(SteamOxidation）Si+2H2O→SiO2+2H2AthightemperatureH2OisdissociatedtoHandH-OH-OdiffusesfasterinSiO2thanO2SteamoxidationhashighergrowthratethandryoxidationBlanketFieldOxideIsolation水29<100>SiliconWetOxidationRate<100>SiliconWetOxidationRa30濕氧氧化(WetOxidation)濕氧氧化法是將干燥純凈的氧氣，在通入氧化爐之前，先經過一個水浴瓶，使氧氣通過加熱的高純去離子水，攜帶一定量的水汽，濕氧氧化法的氧化劑是氧氣和水的混合物。Si+O2→SiO2Si+2H2O→SiO2+2H2濕氧氧化(WetOxidation)濕氧氧化法是將干燥純凈31氧化速率溫度濕氧或干氧厚度壓力圓片晶向(<100>或<111>)硅中雜質氧化速率溫度32氧化速率與溫度氧化速率對溫度很敏感，指數規(guī)律溫度升高會引起更大的氧化速率升高物理機理：溫度越高，O與Si的化學反應速率越高；溫度越高，O在SiO2中的擴散速率越高。氧化速率與溫度氧化速率對溫度很敏感，指數規(guī)律33氧化速率與圓片晶向<111>表面的氧化速率高于<100>表面<111>表面的Si原子密度高氧化速率與圓片晶向<111>表面的氧化速率高于<100>表面34MuchlowerBandPdiffusionratesinSiO2thanthatinSiB/A為線性速率常數；HClisusedtoremovemobileionsforgateoxidationImmersionindunktankfollowedbyrinse,spindryand/ordrybake(100to125℃)MuchlowerBandPdiffusionratesinSiO2thanthatinSiSteamoxidationhashighergrowthratethandryoxidation氧化薄膜越厚，生長速率越低ComparewithblanketfieldoxideRelievestrongtensilestressofthenitride通常，摻雜濃度越高，氧化層生長速率越高；CapacitordielectricSiO2canbeusedasdiffusionmaskH-OdiffusesfasterinSiO2thanO2Growthratecanincreasefrom1to5percentBoilerSystemBubblerSystem<111>表面的氧化速率高于<100>表面Needverygoodcontroloftemperatureuniformity氧化薄膜越厚，生長速率越低氧化薄膜越厚，生長速率越低濕氧氧化速率MuchlowerBandPdiffusionr35氧化速率與雜質濃度雜質元素和濃度高摻磷的硅有更高的氧化層生長速率，更低密度的氧化層薄膜和更高的刻蝕速率通常，摻雜濃度越高，氧化層生長速率越高；在氧化過程的線性區(qū)(氧化層較薄時)更為顯著。氧化速率與雜質濃度雜質元素和濃度36氧化：雜質堆積和耗盡效應N型雜質(P、As、Sb)在Si中的溶解度高于在SiO2中的溶解度，當SiO2生長時，雜質向Si中移動，這引起雜質堆積或滾雪球效應B傾向于向SiO2中運動，這引起雜質耗盡效應氧化：雜質堆積和耗盡效應N型雜質(P、As、Sb)在Si中的37DepletionandPile-upEffectsDepletionandPile-upEffects38氧化速率與HCl摻雜氧化HClisusedtoreducemobileioncontaminationWidelyusedforgateoxidationprocessGrowthratecanincreasefrom1to5percent氧化速率與HCl摻雜氧化HClisusedtored39氧化速率與不均勻氧化氧化層越厚，氧化速率越小對于更厚的氧化層，O需要更多的時間擴散過氧化層與襯底硅發(fā)生反應氧化速率與不均勻氧化氧化層越厚，氧化速率越小40在干氧中的氧化速率在干氧中的氧化速率41在合成水汽中的氧化速率在合成水汽中的氧化速率42二氧化硅色譜二氧化硅色譜43氧化工藝干氧氧化，薄氧化層－柵氧化層－襯墊氧化層，屏蔽氧化層，犧牲氧化層，等等濕氧氧化，厚氧化層－場氧化層－擴散掩膜氧化層氧化工藝干氧氧化，薄氧化層44HighpurityN2asprocesspurgegasDisadvantage缺點LowergradeN2asidlepurgegas被淺的管溝(STI)所取代ComparewithblanketfieldoxideHigherdielectricstrengthSiO2canbeusedasdiffusionmask高壓清洗或者放在清洗液中加熱漂洗，最后烘干Highpressurescruborimmersioninheateddunktankfollowedbyrinse,spindryand/ordrybake(100to125°C).SiO2canbeusedasdiffusionmaskDanglingBondsandInterfaceCharge氧化速率對溫度很敏感，指數規(guī)律MuchlowerBandPdiffusionratesinSiO2thanthatinSi再在大的玻璃杯中浸泡清洗表面未清洗硅片的熱氧化層Defectsremovalfromsiliconsurface氧化：雜質堆積和耗盡效應H-OdiffusesfasterinSiO2thanO2－襯墊氧化層，屏蔽氧化層，犧牲氧化層，等等氧化薄膜越厚，生長速率越低在氧化過程的線性區(qū)(氧化層較薄時)更為顯著。DryOxidationSystemHighpurityN2asprocesspurg45氧化裝置系統(tǒng)氧化裝置系統(tǒng)46DryOxidationDryO2asthemainprocessgasHClisusedtoremovemobileionsforgateoxidationHighpurityN2asprocesspurgegasLowergradeN2asidlepurgegasDryOxidationDryO2asthemai47DanglingBondsandInterfaceChargeDanglingBondsandInterfaceC48WetOxidationProcessFaster,higherthroughputThickoxide,suchasLOCOSDryoxidehasbetterqualityWetOxidationProcessFaster,h49WaterVaporSourcesBoilerBubblerFlushPyrogenicWaterVaporSourcesBoiler50BoilerSystemBoilerSystem51BubblerSystemBubblerSystem52FlushSystemFlushSystem53PyrogenicSteamSystemPyrogenicSteamSystem54PyrogenicSystemAdvantage–Allgassystem–PreciselycontrolofflowrateDisadvantage–Introducingofflammable,explosivehydrogenTypicalH2:O2ratioisbetween1.8:1to1.9:1.PyrogenicSystemAdvantage55RapidThermalOxidationForgateoxidationofdeepsub-microndeviceVerythinoxidefilm,<30?NeedverygoodcontroloftemperatureuniformityRTOwillbeusedtoachievethedevicerequirement.RapidThermalOxidationForgat56H-OdiffusesfasterinSiO2thanO2–Lowerstepheight更低臺階高度氧化層越厚，氧化速率越小H-OdiffusesfasterinSiO2thanO2–Betterisolation更好的隔離FastergrowthrateDryO2asthemainprocessgasBlanketFieldOxideIsolationB傾向于向SiO2中運動，這引起雜質耗盡效應BlanketFieldOxideIsolation－襯墊氧化層，屏蔽氧化層，犧牲氧化層，等等DryO2asthemainprocessgasBlanketfieldoxide通常，摻雜濃度越高，氧化層生長速率越高；Blanket