5. Poly Etch Introduction

P.1多晶矽(複晶矽)蝕刻簡介Poly(Silicon)EtchIntroductionP.2Outline:PolyprocessintroductionProcessgasintroductionPolyetcherintroduction-RIEintroduction-PolychamberintroductionP.3Polyprocessintroduction•DryetchmechanismP.4EtchProcessSequenceP.5PolysiliconEtch–ProcessstepProcesssteps:BreakthroughRemovalofnativeoxide,energeticAr+bombardmentMainetchHighpolyetchrate,ClandHBrchemistryEndpoint/timemodeOveretchPreciselyprofilecontrolbychamberP.6ProcessControlEndpointDetection光學放射頻譜分析是最有用的終點偵測器，因為它可以很容易地在蝕刻設備上面且不影響蝕刻的進行，還有他對反映的些微變化可以靈敏的偵測，以及可提供有關蝕刻反應過程中，許多有用的資訊。但是光學放射頻譜分析仍有一些缺點與限制：一是光線強度正比於蝕刻速率，所以對蝕刻速率較慢的蝕刻而言將變的難以偵測。另一個限制則是當蝕刻面積很小時，信號強度將會不足，而使終點偵測失敗，如二氧化碳接觸窗的蝕刻。若在接觸窗外提供一大面積SiO2來蝕刻，則可增強信號強度，但此大區域的蝕刻速率又大於接觸窗的蝕刻速率，亦即微負載效應(MicroloadingEffect)，因此仍須要過度蝕刻以確保接觸窗能完全蝕刻。Uniformity:123P.7OpticalEmissionSpectroscopyP.8EtchEndpointWavelengthsFilmEtchantWavelength(?Emitter2614AlClAlCl2,BCl33962AlPolySiCl22882Si6156O3370N23862CN7037FSi3N4CF4/O26740N7037F4835COSiO2CF4andCHF36156OPSG,BPSGCF4andCHF32535PWSF67037FWavelength(Å)P.9ProcessgasintroductionGeneraletchprocessgasPolysilicon:-Cl2/O2/He-HBr/O2/HeSitrench-Cl2/HBr/O2/He-NF3/Cl2/O2/HeAlCu/Ti/TiN-Cl2/BCl3/Ar/N2/CHF3/CH4SiO2:-CF4/CHF3/O2/Ar-C4F8/CO/Ar-CHF3/CO/Ar-C5F8/C4F6…Si3N4:-CF4/CHF3/Ar-SF6/CF4/HBr/Ar-CH3F/CH2F2/O2/ArP.10ProcessgasintroductionP.11Processgasintroduction–PolyetchCF4forbreakthroughnormalgasEQPROCESSHBrCl2BCl3HClSF6NF3HeO2O2CF4CHF3LAM9400DTPHMTEL/AMATDTPLNetchRecessetchSietchCollaretchWsietchPolyetchLAM9600M1AMATDPS+M2RecessAAGCAMATDPSAMATDPS+LAM9400Poly/MetaletchusedgasP.12PolyetcherintroductionP.13PolyetcherintroductionP.14ReactiveIonEtch(RIE)CombinationofchemicalandphysicaletchPlasmaprocess,ionbombardmentplusfreeradicalsMisleadingname,shouldbecalledionassistantetch(IAE)HighandcontrollableetchrateAnisotropicandcontrollableetchprofileGoodandcontrollableselectivityAllpatternedetchesareRIEprocessesin8”fabsP.15SchematicofanRIESystemProcessgasesPlasmaProcesschamberBy-productstothepumpChuckRFPowerHeliumForbacksidecoolingMagnetcoilsWaferP.16Polyetcherintroduction–TEL88SCCMTEL88SCCM:DTetchP.17Polyetcherintroduction–TEL88SCCMPlasmaMatcher~~HighfrequencyRFGenerator40MHzLowfrequencyRFGenerator3.2MHzHighLowHighBiasPlasmadensitySCCMDTcancontrolBias&Plasmadensitybytheindependence.HighFrequency:PlasmadensitycontrolLowFrequency:BiascontrolP.18Polyetcherintroduction–HARTSource:Gen:60MHZ200mm2KW300mm2.7KW(Higherpowerlaterifneeded)Match:AutoTuningBias:2MHZGen.&MatchSource:60MHZGen.&MatchBias:Gen:2MHZFrequencytuning200mm2.5KW300mm2.5KW(Higherpowerifneededlater)Match:FixedAMATHART:DTetchP.19TCPchamberbenefitTransferringCoupledPlasmaP.20Polyetcherintroduction–LAM9400QZcoverCoilLAM9400:DTPHMetch/GCetch/CTMOetchBufferLoadlockOrientorP.21LAM9400ProcesscontrolUndopedpolyetch:WSietch:Polyetch:-Referenceforrecipefinetune.P.22Polyetcherintroduction–DPS&DPS+DPSChamber:Recess1/Recess2/BSRecessetchP.23Polyetcherintroduction–DPS&DPS+DPS+Chamber:AAsiliconetchP.24DPSPolyV-ElectrodeDomewithIEPCeramicDomeMountingRingV-ElectrodeIEPCeramicDomeAssemblyFeatures:@UniformlydistributesRFenergyacrossdome@Reducesdefectlevel@Depositioninchamberismoreuniformacrossdome@Overalldepositionisdecreased.@Non-consumablePolyetcherintroduction–DPS&DPS+DomeP.25Polyetcherintroduction–DPS&DPS+E.S.C.DPSDPS+polyimide(-CO-NH-)(Al2O2)ceramicP.26Polyetcherintroduction–DPS&DPS+DPSandDPSplusCompare•ThrottleDPSDPSplusP.27TheEndPolyetchintroduction