SMT-06_Contamination_CD

©2001byPrenticeHallSemiconductorManufacturingTechnologybyMichaelQuirkandJulianSerdaSemiconductorManufacturingTechnologyMichaelQuirk&JulianSerda©October2001byPrenticeHallChapter6ContaminationControlinWaferFabs©2001byPrenticeHallSemiconductorManufacturingTechnologybyMichaelQuirkandJulianSerdaObjectivesAfterstudyingthematerialinthischapter,youwillbeableto:1.Stateanddescribethefivedifferenttypesofcleanroomcontaminationanddiscusstheproblemsassociatedwitheachcontamination.2.Listsevensourcesofcontaminationinacleanroomanddescribehoweachoneaffectswafercleanliness.3.Interpretandusetheclassnumberforcleanroomairquality.4.Stateanddiscusssevenappropriateactionsfortechniciansenteringacleanroomthatfollowacceptableprotocol.5.Describethedifferentaspectsofaultracleancleanroomfacility,includingairfiltering,electrostaticdischarge,ultrapureDIwaterandprocessgases.6.Explainhowmodernworkstationdesignandaminienvironmentcontributestocontaminationreduction.7.Statethechemistryofthetwostandardwetcleaningmethods,explainthetypeofcontaminationremovedbyeach,anddiscusswetcleaningmodificationsandalternatives.8.Describethedifferenttypesofwetcleaningequipmentandstatehoweachcleaningprocesscontributestowafercleanliness.©2001byPrenticeHallSemiconductorManufacturingTechnologybyMichaelQuirkandJulianSerdaWaferContaminantsEmbeddedparticleSurfacecontaminantFigure6.1©2001byPrenticeHallSemiconductorManufacturingTechnologybyMichaelQuirkandJulianSerdaWaferFabCleanroomPhotographcourtesyofAdvancedMicroDevices,mainfabcorridorPhoto6.1©2001byPrenticeHallSemiconductorManufacturingTechnologybyMichaelQuirkandJulianSerdaTypesofContaminationandTheProblemsTheyCause•Particles•MetallicImpurities•OrganicContamination•NativeOxides•ElectrostaticDischarge©2001byPrenticeHallSemiconductorManufacturingTechnologybyMichaelQuirkandJulianSerdaRelativeSizeofParticlesFigure6.2Millimeters110-110-210-310-410-610-710-510AtomsSizeofsinglemoleculesofmatterHazeThinsmokeCloudparticlesAtmosphericdustFogparticlesSandDustPebbles©2001byPrenticeHallSemiconductorManufacturingTechnologybyMichaelQuirkandJulianSerdaDefectfromParticlesMicrographcourtesyofAMD,particleunderneathphotoresistpatternPhoto6.2©2001byPrenticeHallSemiconductorManufacturingTechnologybyMichaelQuirkandJulianSerdaRelativeSizeofHumanHairto0.18mmFeatureSizeContactholeLinewidthSpace~90mmMinimumICfeaturesize=0.18mm90mm0.18mm=500Therelativesizeofthehumanhairisapproximately500timesthesizeofthesmallestfeaturesizeonanintegratedcircuit.Asmallexampleofasegmentfromalargerintegratedcircuit.CrosssectionofhumanhairFigure6.3©2001byPrenticeHallSemiconductorManufacturingTechnologybyMichaelQuirkandJulianSerdaParticlesPerWaferPerPassonaWaferProcessToolInitialparticlecountbeforethewaferisinsertedinprocesstool.Initialparticlecountafterthewaferpassesthroughtheprocesstool.Particlesareaddedtothewaferbytheprocesstool.Figure6.4©2001byPrenticeHallSemiconductorManufacturingTechnologybyMichaelQuirkandJulianSerdaTypicalMetalImpuritiesHeavyMetalsAlkaliMetalsIron(Fe)Sodium(Na)Copper(Cu)Potassium(K)Aluminum(Al)Lithium(Li)Chromium(Cr)Tungsten(W)Titanium(Ti)©2001byPrenticeHallSemiconductorManufacturingTechnologybyMichaelQuirkandJulianSerdaMobileIonicContaminantAlteringThresholdVoltageFigure6.5++++++++++++++++++SourceDrainP-siliconsubstrateGateN+N+-Vs+Vd+VgIoniccontaminationalterstheelectricalcharacteristicsofatransistor.Conductionofelectrons++GateoxidePolysilicon++++++++++++++©2001byPrenticeHallSemiconductorManufacturingTechnologybyMichaelQuirkandJulianSerdaNativeOxideNativeoxidelinesthebottomofthecontacthole,creatingpoorelectricalcontactbetweentungstenandthedopedsiliconregion.Nativeoxidegrowsinsidethecontactholepriortotungstendeposition.TungstenplugActiveregioninsiliconInterlayerdielectricInterlayerdielectricOxideinsulatesthecontact.Figure6.6©2001byPrenticeHallSemiconductorManufacturingTechnologybyMichaelQuirkandJulianSerdaParticlesAttractedtoaChargedWafer---------------------------------------------------------------Figure6.7©2001byPrenticeHallSemiconductorManufacturingTechnologybyMichaelQuirkandJulianSerdaSourcesandControlofContaminationSevenSourcesofContaminationinaWaferFab:•Air•Humans•Facility•Water•ProcessChemicals•ProcessGases•ProductionEquipmentTable6.1©2001byPrenticeHallSemiconductorManufacturingTechnologybyMichaelQuirkandJulianSerdaDefinitionofAirborneParticulateCleanlinessClassesPerFederalStandard209ETable6.2Particles/ft3Class0.1mm0.2mm0.3mm0.5mm5mm13.50x107.703.001.00103.50x1027.50x103.00x101.00x1011007.50x1023.00x1021.00x1021,0001.00x1037.0010,0001.00x1047.00x10100,0001.00x1057.00x102©2001byPrenticeHallSemiconductorManufacturingTechnologybyMichaelQuirkandJulianSerdaParticlesEmittedbyHumanActivitiesTable6.3SourceofParticlesAverageNumberofParticlesperMinute0.3mmMotionless(sittingorstanding)100,000Movinghands,arms,trunk,neckandhead500,000Walkingat2milesperhour5,000,000Walkingat3.5milesperhour7,500,000CleanestSkin(persquarefoot)10,000,000©2001byPrenticeHallSemiconductorManufacturingTechnologybyMichaelQuirkandJulianSerdaTechnicianinCleanroomGarmentPhotoc