Thin wafer grinding 超薄晶圆减薄

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1、RecentDevelopmentsinThinwafergrinding–AnApplicationReviewThomasPuthanangady,RamaVedantham,JIkedaPhD.SaintGobainAbrasives-NortonSalKassir–StrasbaughSamKaoPhD–Tru-SiOutline•Introduction•WheredoesB/Gfitin•Whydoit•Whataresometypicalproblemsencountered•ObjectiveofPresentation•Experim

2、entalmethod•Machineusedtogrind,Wheelsusedtogrind,metrology•equipment,recipeused•ExperimentalResults5.ConclusionsWaferFabsWorkFlowBackgrindingWaferEpitaxyBack-endManufacturingDepositionCMPRTPIonImplantSpinOnMaskSEMInspectPhotoLithographyEtchingThinWaferProcessinghandlingBackDe-Et

3、chGrindTapeFlipChipWaferWaferDieDicingWirebondEncapsulationTestMountAttachProfileofTypicalSiliconWaferLeftsideofthiswaferwasground.GrindingWaferswithBevelCADDrawingsillustratetheeffectofthebevelongrindingthinwafers.BevelFullRadiusThinWaferwithBevelandDeviceDevice1in1in=200µmClos

4、eUpofThinWaferWithBevel•Closeupshowsthatthetipofthethinwaferisverythin.•Thethintipleadstochippingaroundtheedgeofthewafer.•Thedamagepropagatesaroundwaferandfurtherintowafer.x=TotalWaferThickness-CircuitryThicknessy=Function(x)x0.25in.yVeryThin1in=200µmThinWaferGrinding•Thinnerwaf

5、ersdonothavetheinherentmasstoresistbendingstressesdueto•Gravity•Residualgrinding/machiningstresses•ThisresultsinBowandWarp•Createshandlingissuesandmayultimatelyresultinwaferbreakage•Thiseffectismorepronouncedin200mmandlargerwafersObjectiveEvaluateeffectofgrindingwheelspecificati

6、onon8”thinwafersforoptimumtoolselection>Effectofgritsizeandgrade(wheelhardness)onthinwafer•Surfacestresses•Waferstrength•SurfaceRoughnesscharacteristicsFinalwaferthickness:125umTestMethodoloy-8”wafersmanuallytapedusingavacuumchuck-Testwheelsusedtogrind25nosof8”waferseachto125umt

7、hicknessontheStrasbaugh7AFgrinder-Theforceduringgrinding,cycletimeandthewheelwearratesweremonitored.-Waferswerede-tapedmanually-Surfacefinish(Ra,Rt),WaferBowandStrengthmeasured-Chippingwasclassifiedaspernumberandsizeofchipsusingamicroscope>Cleanedges:NC(NoChippageatall)>Roughedg

8、ewithnovisiblechippage:RE(RoughEdge)>Onechipwit