现代CMOS工艺基本流程(英文)ppt课件.ppt

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1、BasicCMOSProcessFlow现代CMOS工艺基本流程1BasicCMOSProcessFlowStartingPoint:Puresiliconwafer(heavily-doped)withalightly-dopedepitaxial(epi)layer.Anepilayerisusedtoprovideacleanerlayerfordeviceformationandtoprevent“latch-up”ofCMOStransistors.SiliconSubstrateP+~2microns~725

2、micronsSiliconEpiLayerP-21.ShallowTrenchFormationGrowPadOxide:Averythin(~200Å)layerofsilicondioxide(SiO2)isgrownonthesurfacebyreactingsiliconandoxygenathightemperatures.Thiswillserveasastressrelieflayerbetweenthesiliconandthesubsequentnitridelayer.SiliconSubstrat

3、eP+SiliconEpiLayerP-PadOxide3ShallowTrenchFormationDepositSiliconNitride:Alayer(~2500Å)ofsiliconnitride(Si3N4)isdepositedusingChemicalVaporDeposition.Thiswillserveasapolishstoplayerduringtrenchformation.SiliconSubstrateP+SiliconEpiLayerP-SiliconNitride4ShallowTre

4、nchFormationPatternPhotoresistforDefinitionofTrenches:Oneofthemostcriticalpatterningstepsintheprocess.0.5-1.0μmofresistisspun,exposed,anddeveloped.SiliconSubstrateP+SiliconEpiLayerP-SiliconNitridePhotoresist5ShallowTrenchFormationEtchNitrideandPadOxide:Areactivei

5、onetch(RIE)utilizingfluorinechemistryisused.SiliconSubstrateP+SiliconEpiLayerP-SiliconNitridePhotoresist6ShallowTrenchFormationEtchTrenchesinSilicon:Areactiveionetch(RIE)utilizingfluorinechemistryisused.Definestransistoractiveareas.SiliconSubstrateP+SiliconEpiLay

6、erP-SiliconNitridePhotoresistTransistorActiveAreasIsolationTrenches7ShallowTrenchFormationRemovePhotoresist:Anoxygenplasmaisusedtoburnofftheresistlayer.SiliconSubstrateP+SiliconEpiLayerP-SiliconNitrideTransistorActiveAreasIsolationTrenches8ShallowTrenchFormationF

7、illTrencheswithOxide:ACVDoxidelayerisdepositedtoconformallyfillthetrenches.Theoxidewillprevent“cross-talk”betweenthetransistorsinthecircuit.SiliconSubstrateP+SiliconEpiLayerP-SiliconNitrideFuturePMOSTransistorSiliconDioxideFutureNMOSTransistorNocurrentcanflowthro

8、ughhere!9ShallowTrenchFormationPolishTrenchOxide:ThesurfaceoxideisremovedusingaChemicalMechanicalPolish(CMP).TheCMPprocessisdesignedtostoponsiliconnitride.Sili