SMT-16EtchCD

©2001byPrenticeHallSemiconductorManufacturingTechnologybyMichaelQuirkandJulianSerdaSemiconductorManufacturingTechnologyMichaelQuirk&JulianSerda©October2001byPrenticeHallChapter16Etch©2001byPrenticeHallSemiconductorManufacturingTechnologybyMichaelQuirkandJulianSerda©2001byPrenticeHallSemiconductorManufacturingTechnologybyMichaelQuirkandJulianSerdaObjectivesAfterstudyingthematerialinthischapter,youwillbeableto:1.Listanddiscusseightimportantetchparameters.2.Explaindryetch,includingitsadvantagesandhowetchingactiontakesplace.3.Listanddescribetheequipmentsystemsforsevendryplasmaetchreactors.4.Explainthebenefitsofhigh-densityplasma(HDP)etchandthediscussthefourtypesofHDPreactors.5.Giveanapplicationexamplefordielectric,siliconandmetaldryetch.6.Discusswetetchanditsapplications.7.Explainhowphotoresistisremoved.8.Discussetchinspectionandimportantqualitymeasures.©2001byPrenticeHallSemiconductorManufacturingTechnologybyMichaelQuirkandJulianSerdaApplicationsforWaferEtchinCMOSTechnologyPhotoresistmaskFilmtobeetched(a)Photoresist-patternedsubstrate(b)SubstrateafteretchPhotoresistmaskProtectedfilmFigure16.1©2001byPrenticeHallSemiconductorManufacturingTechnologybyMichaelQuirkandJulianSerdaProcessFlowinaWaferFabImplantDiffusionTest/SortEtchPolishPhotoCompletedwaferUnpatternedwaferWaferstartThinFilmsWaferfabrication(front-end)UsedwithpermissionfromAdvancedMicroDevicesFigure16.2©2001byPrenticeHallSemiconductorManufacturingTechnologybyMichaelQuirkandJulianSerdaEtchProcessCategoriesofEtchProcesses•WetEtch•DryEtch•ThreeMajorMaterialstobeEtched–Silicon–Dielectric–Metal•PatternedEtchVersusUnpatternedEtch©2001byPrenticeHallSemiconductorManufacturingTechnologybyMichaelQuirkandJulianSerdaEtchParameters•Etchrate•Etchprofile•Etchbias•Selectivity•Uniformity•Residues•Polymerformation•Plasma-induceddamage•Particlecontaminationanddefects©2001byPrenticeHallSemiconductorManufacturingTechnologybyMichaelQuirkandJulianSerdaEtchRateTStartofetchEndofetcht=elapsedtimeduringetchT=changeinthicknessFigure16.3©2001byPrenticeHallSemiconductorManufacturingTechnologybyMichaelQuirkandJulianSerdaWetChemicalIsotropicEtchIsotropicetch-etchesinalldirectionsatthesamerateSubstrateFilmResistFigure16.4©2001byPrenticeHallSemiconductorManufacturingTechnologybyMichaelQuirkandJulianSerdaAnisotropicEtchwithVerticalEtchProfileAnisotropicetch-etchesinonlyonedirectionResistSubstrateFilmFigure16.5©2001byPrenticeHallSemiconductorManufacturingTechnologybyMichaelQuirkandJulianSerdaSidewallProfilesforWetEtchVersusDryEtchTable16.1TypeofEtchSidewallProfileDiagramWetEtchIsotropicIsotropic(dependingonequipment¶meters)Anisotropic(dependingonequipment¶meters)Anisotropic–TaperDryEtchSiliconTrench©2001byPrenticeHallSemiconductorManufacturingTechnologybyMichaelQuirkandJulianSerdaEtchBias(b)BiasSubstrateResistFilm(a)BiasResistFilmSubstrateWbWaFigure16.6©2001byPrenticeHallSemiconductorManufacturingTechnologybyMichaelQuirkandJulianSerdaEtchingUndercutandSlopeUndercutSubstrateResistFilmOveretchFigure16.7©2001byPrenticeHallSemiconductorManufacturingTechnologybyMichaelQuirkandJulianSerdaEtchSelectivityS=EfErEfNitrideOxideErFigure16.8©2001byPrenticeHallSemiconductorManufacturingTechnologybyMichaelQuirkandJulianSerdaEtchUniformityMeasureetchrateat5to9locationsoneachwafer,thencalculateetchuniformityforeachwaferandcomparewafer-to-wafer.Randomlyselect3to5wafersinalotFigure16.9©2001byPrenticeHallSemiconductorManufacturingTechnologybyMichaelQuirkandJulianSerdaPolymerSidewallPassivationforIncreasedAnisotropyPlasmaionsResistOxidePolymerformationSiliconFigure16.10©2001byPrenticeHallSemiconductorManufacturingTechnologybyMichaelQuirkandJulianSerdaDryEtch•AdvantagesofDryEtchoverWetEtch•EtchingAction•PotentialDistribution©2001byPrenticeHallSemiconductorManufacturingTechnologybyMichaelQuirkandJulianSerdaAdvantagesofDryEtchoverWetEtch1.Etchprofileisanisotropicwithexcellentcontrolofsidewallprofiles.2.GoodCDcontrol.3.Minimalresistliftingoradhesionproblems.4.Goodetchuniformitywithinwafer,wafer-to-waferandlot-to-lot.5.Lowerchemicalcostsforusageanddisposal.Table16.2©2001byPrenticeHallSemiconductorManufacturingTechnologybyMichaelQuirkandJulianSerdaPlasmaEtchProcessofaSiliconWafer8)By-productremoval1)EtchantgasesenterchamberSubstrateEtchprocesschamber2)Dissociationofreactantsbyelectricfields5)Adsorptionofreactiveionsonsurface4)Reactive+ionsbombardsurface6)SurfacereactionsofradicalsandsurfacefilmExhaustGasdeliveryRFgeneratorBy-products3)Recombinationofelectronswithatomscreatesplasma7)Desorptionofby-productsCathodeAnodeElectricfieldllAnisotropicetchIsotropicetchFigure16.11©2001byPrenticeHallSemiconductorManufacturingTechnologybyMichaelQuirkandJulianSerdaChemicalandPhysicalDryEtchMechanismsReactive+ionsbombardsurfaceSurfacereactionsofradicals+surfacefilmDesorptionofby-productsAnisotropicetchIsotropicetchSputteredsurfacematerialChemicalEtchingPhysicalEtchingFigure16.12©2001byPrenticeHallSemiconductorManufacturingTechnologybyMichaelQuirkandJulianSerdaChemicalVersusPhysicalDryPlasmaEtchingEtchParameterPhysicalEt