道功率芯片背金工艺优化和缺陷改善

上海交通大学硕士学位论文0.35μm垂直沟道功率芯片背金工艺优化和缺陷改善姓名：刘瑜申请学位级别：硕士专业：软件工程指导教师：程秀兰20081201-IV-µmµmµmµm-V-0.35µmUMOSFETBacksideProcessAnalysisandImproveAbstractBacksidemetalprocessisthemostimportantstepofUMOSFETprocess.Inthetraditionalbacksidemetalprocess,ICearlyfailurealwayshappensbecauseoftheunstabeleadhesiveabilitybetweenbacksidemetalandwaferbackside,whichiscausedbysomereasonssuchasoverbacksidegrinding,surfaceroughnessmismatch,monolayermetalevaporation,etc.Inordertoimprovetheyieldandthereliability,thenewwaferprocessbaselineofbacksideroughnessandmetalevaporationissetupandallkindsofdefectsolvingmethodsisofferedinthepaper.Firstly,forthebacksidewaferroughness,thetwodifferentetchingsolutionsareresearched:theacidsolutionandtheKOHone.Intheacidsolution,themostappropriatevolumeratioof33%HFand70%HNO3is7:1andaddwaterby10%,whichoffersthebestroughnesswafersurfaceandeasycontroletchrateforthemassproduction.IntheKOHone,after15minutesreactioninthe30%KOHsolution,thewafergetsthereasonablesurfacecondition,whichissuitableforthenextmetalevaporationstep.it’sprovedthattheacidsolutionisbetterthantheKOHoneinthemassproductionbasedonlotsofexperimentrawdata.Secondly,thebacksidemetalevaporationprocessparametersareoptimized.Themultilayermetal(Ti,Ni,andAg)systemisselected.Thewaferhasbetterbacksidemetaladhesiveabilityafterpreheatedto200thantheonewithoutthat.Themetalsurfaceparticleproblemisbasicallysolvedbyaddingthemetalpre-moltentime(1MinasTi,7MinasNi,and3MinasAg).Atlast,thecausesofsomedefectssuchaswaferbending,frontsidediscolorandbacksidemetalpeelingsareanalyzed,andthecorrespondingsolvingmethodsaresummarized.Acompleteseriesflowofbacksidemetalisfinalizedinthispaper.Astheflowstudiedabovehasbeenimplementedinmassproduction,0.35µmUMOSproductgetsstablereliability,andtheyieldisgreatlyimprovedaswell.Keywords:0.35µmVerticalTrenchUMOSBacksidemetalprocess,Defect-II--III--1-11.1-2--3-1Fig12007PowerSemiconductorevolution1.21.2.1-4-2VVMOSFig2VVMOSstructure-5-3VUMOSFig3VUMOSstructure1.2.24VDMOSFig4VDMOSstructure-6-1.2.3-7-5Fig56PowerMOSFETFig6PowerMOSFETstructure-8-7PowerMOSFETFig7PowerMOSFETsort1.3-9-8PowerMOSFETFig8PowerMOSFETstructure-10--11-1.4TEOSTrenchTEOSTrench/POLY1POLYB+As+BPTEOS1ANISOBF2+B+Ti+TiNRTAAl2SiCuAlHardbakeUVAl1SiTEOSSiNPADHardbakeSi-12-1.5-13-µmµm-14-20.35µm2.19Fig9backsidemetalprocessflow2.1.1-15-2.1.2µmµmµm2.1.32.1.4-16-10Fig10frontsidedetapeprocess2.1.5-17-1Table1Siandmetalperformancecomparingµm1.42.441420Si420.198.51160Ti1.594.2719.3962Ag6.840.89912.71453Ni2.353.1114.21064Au1.68416.81083Cu12.90.878.51857Cr2.652.3723.2660AlSi/SiO225/10-6?·cm25/W·cm-1·K-125/10-6K-1/C1.42.441420Si420.198.51160Ti1.594.2719.3962Ag6.840.89912.71453Ni2.353.1114.21064Au1.68416.81083Cu12.90.878.51857Cr2.652.3723.2660AlSi/SiO225/10-6?·cm25/W·cm-1·K-125/10-6K-1/C-18-,Ti/Ni/AgTi/Ni/AuM·18571111Fig11vacuummetalevaporationmachine-19-0.10.22.1.62.2µm-20--21-30.35µm3.112SEMFig12wafersurfaceSEMaftergrindingµmµmµm-22-µmµm13Fig13Waferintensityandetchratecorrelation-23-3.214siFig14Si’sreactionin-24-3.3-25-3.3.12HFHNO3Table2SietchratecorrelationwithHF/HNO3-26-15siFig15Sietchratecorrelationwithacidconcentration-27-µm3.3.2-28-3siTable3SietchratecorrelationwithaddingH2Oratio16siFig16SietchratecorrelationwithaddingH2Oratio-29-4HF-HNO3SiH2OTable4WafersurfaceSEMmatchwithaddingH2Oratioµmµm3.3.3-30--31-5HF-HNO3SiTable5Sietchratecorrelationwithreactiontime17siFig17Sietchratecorrelationwithreactiontime7:133%HF70%HNO310%15-32-3.43.4.1KOH6siTable6SietchratecorrelationwithKOHconcentration-33-18siFig18SietchratecorrelationwithKOHconcentration2002M.A.Goslvez[43]HOHHOHOH-34-OHOHOHOHOHOH/OHOH(HHOHHOHOHevµm/h•µm/h]7Table7SietchratecorrelationwithKOHconcentrationandtemperatureTemperature[?]%KOH20o30o40o50o60o70o80o90o100o101.493.26.713.325.24682140233151.563.47.014.026.54986147245201.573.47.114.026.74986148246251.533.36.913.625.94784144239301.443.16.512.824.44579135225351.322.95.911.822.34172124206401.172.55.310.519.93664110184451.012.24.69.017.1315595158500.841.83.87.514.2264679131550.661.43.05.911.2213662104600.501.12.24.48.415274778-35-3.4.230KOH251015,30,15min,30%KOH1519si30%KOH15minSEMFig19wafersurfaceSEMafterSietch15minin30%KOH3.5-36-20Fig20backsidemetalpeelingwafernumberintheKOHandHF+HNO33.6m-37-30%KOH15minµm-38-40.35m4.14.1.1VDMOS21VDMOSFig21VDMOSverticalstructure1Si.2Si-39-3454.1.24.1.322Fig22wafersurfaceparticle-40-23SEMFig23wafersurfaceparticleSEM24EDXFig24wafersurfaceparticleEDXresult-41-4.2-42-25Fig25Normalmetalperformance-43-26Fig26wafercrosssectionaftermetalevaporation4.3µmµmµm-44-27Fig27monitormetalpeelingmethod4.4-45-1088Table8metalpeelingcorrelationwithwaferincreasetemperature4.59TiTable9particlenumbercorrelationwithTipre-fusetemperature-46-10NiTable10particlenumbercorrelationwithNipre-fusetemperature11AgTable11particlenumbercorrelationwithAgpre-fusetemperature4.60.35µmUMOS-47-1TiNiAg22003Ti1Ni7Ag34IM001-48-50.35m5.1µm28warpageFig28waferwarpageissue2-49-29Fig29waferfrontsidediscolorissue330Fig30waferfrontsideresidue-50-31Fig31waferbacksidemetalpeeling32Fig32reactionresidueonwafersu