SMT-04WaferPrepCD

©2001byPrenticeHallSemiconductorManufacturingTechnologybyMichaelQuirkandJulianSerdaSemiconductorManufacturingTechnologyMichaelQuirk&JulianSerda©October2001byPrenticeHallChapter4SiliconandWaferPreparation©2001byPrenticeHallSemiconductorManufacturingTechnologybyMichaelQuirkandJulianSerdaObjectivesAfterstudyingthematerialinthischapter,youwillbeableto:1.Describehowrawsiliconisrefinedintosemiconductorgradesilicon.2.Explainthecrystalstructureandgrowthmethodforproducingmonocrystalsilicon.3.Discussthemajordefectsinsiliconcrystal.4.Outlineanddescribethebasicprocessstepsforwaferpreparation,startingfromasiliconingotandfinishingwithawafer.5.Stateanddiscusssevenqualitymeasuresforwafersuppliers.6.Explainwhatisepitaxyandwhyitisimportantforwafers.©2001byPrenticeHallSemiconductorManufacturingTechnologybyMichaelQuirkandJulianSerdaSemiconductor-GradeSiliconStepstoObtainingSemiconductorGradeSilicon(SGS)StepDescriptionofProcessReaction1Producemetallurgicalgradesilicon(MGS)byheatingsilicawithcarbonSiC(s)+SiO2(s)Si(l)+SiO(g)+CO(g)2PurifyMGsiliconthroughachemicalreactiontoproduceasilicon-bearinggasoftrichlorosilane(SiHCl3)Si(s)+3HCl(g)SiHCl3(g)+H2(g)+heat3SiHCl3andhydrogenreactinaprocesscalledSiemenstoobtainpuresemiconductor-gradesilicon(SGS)2SiHCl3(g)+2H2(g)2Si(s)+6HCl(g)Table4.1©2001byPrenticeHallSemiconductorManufacturingTechnologybyMichaelQuirkandJulianSerdaCrystalStructure•AmorphousMaterials•UnitCells•PolycrystalandMonocrystalStructures•CrystalOrientation©2001byPrenticeHallSemiconductorManufacturingTechnologybyMichaelQuirkandJulianSerdaSiHCl3PolycrystallinesiliconrodSiemensReactorforSGSiliconFigure4.1©2001byPrenticeHallSemiconductorManufacturingTechnologybyMichaelQuirkandJulianSerdaAtomicOrderofaCrystalStructureFigure4.2©2001byPrenticeHallSemiconductorManufacturingTechnologybyMichaelQuirkandJulianSerdaAmorphousAtomicStructureFigure4.3©2001byPrenticeHallSemiconductorManufacturingTechnologybyMichaelQuirkandJulianSerdaUnitCellin3-DStructureUnitcellFigure4.4©2001byPrenticeHallSemiconductorManufacturingTechnologybyMichaelQuirkandJulianSerdaFaced-centeredCubic(FCC)UnitCellFigure4.5©2001byPrenticeHallSemiconductorManufacturingTechnologybyMichaelQuirkandJulianSerdaSiliconUnitCell:FCCDiamondStructureFigure4.6©2001byPrenticeHallSemiconductorManufacturingTechnologybyMichaelQuirkandJulianSerdaPolycrystallineandMonocrystallineStructuresPolycrystallinestructureMonocrystallinestructureFigure4.7©2001byPrenticeHallSemiconductorManufacturingTechnologybyMichaelQuirkandJulianSerdaAxesofOrientationforUnitCellsZXY1110Figure4.8©2001byPrenticeHallSemiconductorManufacturingTechnologybyMichaelQuirkandJulianSerdaMillerIndicesofCrystalPlanesZXY(100)ZXY(110)ZXY(111)Figure4.9©2001byPrenticeHallSemiconductorManufacturingTechnologybyMichaelQuirkandJulianSerdaMonocrystalSiliconGrowth•CZMethod–CZCrystalPuller–Doping–ImpurityControl•Float-ZoneMethod•ReasonsforLargerIngotDiameters©2001byPrenticeHallSemiconductorManufacturingTechnologybyMichaelQuirkandJulianSerdaCrystalseedMoltenpolysiliconHeatshieldWaterjacketSinglecrystalsiliconQuartzcrucibleCarbonheatingelementCrystalpullerandrotationmechanismCZCrystalPullerFigure4.10©2001byPrenticeHallSemiconductorManufacturingTechnologybyMichaelQuirkandJulianSerdaSiliconIngotGrownbyCZMethodPhotographcourtesyofKayexCorp.,300mmSiingotPhoto4.1©2001byPrenticeHallSemiconductorManufacturingTechnologybyMichaelQuirkandJulianSerdaCZCrystalPullerPhotographcourtesyofKayexCorp.,300mmSicrystalpullerPhoto4.2©2001byPrenticeHallSemiconductorManufacturingTechnologybyMichaelQuirkandJulianSerdaDopantConcentrationNomenclatureConcentration(Atoms/cm3)DopantMaterialType1014(VeryLightlyDoped)1014to1016(LightlyDoped)1016to1019(Doped)1019(HeavilyDoped)Pentavalentnn--n-nn+Trivalentpp--p-pp+Table4.2©2001byPrenticeHallSemiconductorManufacturingTechnologybyMichaelQuirkandJulianSerdaFloatZoneCrystalGrowthRFGasinlet(inert)MoltenzoneTravelingRFcoilPolycrystallinerod(silicon)SeedcrystalInertgasoutChuckChuckFigure4.11©2001byPrenticeHallSemiconductorManufacturingTechnologybyMichaelQuirkandJulianSerda300mm200mm150mm125mm100mm75mm3456812WaferDiameterTrendsFigure4.12©2001byPrenticeHallSemiconductorManufacturingTechnologybyMichaelQuirkandJulianSerdaWaferDimensions&AttributesTable4.3Diameter(mm)Thickness(m)Area(cm2)Weight(grams/lbs)Weight/25Wafers(lbs)15067520176.7128/0.061.520072520314.1653.08/0.12330077520706.86127.64/0.287400825201256.64241.56/0.5313©2001byPrenticeHallSemiconductorManufacturingTechnologybyMichaelQuirkandJulianSerda88die200-mmwafer232die300-mmwaferIncreaseinNumberofChipsonLargerWaferDiameterFigure4.13©2001byPrenticeHallSemiconductorManufacturingTechnologybyMichaelQuirkandJulianSerdaDevelopmentalSpecificationsfor300-mmWaferDimensionsandOrientationParameterUnitsNominalSomeTypicalTolerancesDiametermm300.000.20Thickness(centerpoint)m77525Warp(max)m100Nine-PointThicknessVariation(max)m10NotchDepthmm1.00+0.25,-0.00NotchAngleDegree90+5,-1BackSurfaceFinishBrightEtched/PolishedEdgeProfileSurfaceFinishPolishedFQA(FixedQualityArea–radi