单晶矽相关及材料性质介绍

BulkMaterialPropertyCharacterizationTheFirstQuestionThree2”wafer:1Si,1GaAs,and1InP,Howtoidentifyeachofthem?FormationSiliconIngotGrownbyCZMethodStandardwafersizes„1inch.„2inch(50.8mm).Thickness275µm.„3inch(76.2mm).Thickness375µm.„4inch(100mm).Thickness525µm.„5inch(127mm)or125mm(4.9inch).Thickness625µm.„150mm(5.9inch,usuallyreferredtoas6inch).Thickness675µm.„200mm(7.9inch,usuallyreferredtoas8inch).Thickness725µm.„300mm(11.8inch,usuallyreferredtoas12inchorPizzasizewafer).Thickness775µm.„450mm(18inch).Thickness925µm(expected).StandardwafersizesAnalyticaldiecountestimationTogettheDiePerWafer[DPW]:disthewaferdiameterinmm,andSisthesizeoftargetICsizeinmm2CrystallineorientationTakesiliconasanexample:(a)diamondcubicstructurewithalatticespacingof5.430710Å(b)OrientationisdefinedbytheMillerindexwith[100]or[111]facesbeingthemostcommonUnitcellofSingleCrystalSilicon100OrientationPlane111OrientationPlane100WaferEtchPits111WaferEtchPitsDifferentflatsfororientation„Eachofthewafersisgiveneitheranotchoraflatedge„Thiswillbeusedinorientingthewaferintotheexactpositionforlaterprocedures.DopingTypeDetermination„Iftheminorflatis180degreesfromthemajorflatthewaferisN-type100„Iftheminorflatis90degreestotheleftorrightthewaferisP-type100.„Iftheminorflatis45degreesupontheleftorrightthewaferisN-type111„IftherearenominorflatsthewaferisP-type111.WaferflatsandorientationnotchesWaferflatsandorientationnotchesFinishingOperationsonaSiliconIngottoProduceWafersFigure28.6Finishingoperationsonasiliconingottoproducewafers(a)sawingtheendsofftheingot;(b)grindingoftheendandcylindricalsurfacesofasiliconingot;(c)machiningofanotchorflat;(d)slicingofwafers;(e)endgrindingofwafers;(f)chemical-mechanicalpolishingofwafers.ConductivityTypemeasurements„WaferFlatLocation„Thermalemf„Rectification„HallEffectHotorThermoelectricProbe„Thehot-probeexperimentprovidesaverysimplewaytodistinguishbetweenn-typeandp-typesemiconductorsusingasolderingironandastandardmultimeter.HotorThermoelectricProbe„ThetypeisdeterminedbythesignofthethermalemforSeebeckvoltagegeneratedbyatemperaturegradient„ElectrondiffusefromthehottothecoldregionsettingupanelectricfieldthatopposesthediffusionÎTheelectricfieldproducesapotentialdetectedbythevoltmeter.VmColde-n-typewaferHotorThermoelectricProbeIftake:ThentheJncouldbederivedas:HotorThermoelectricProbeIfwearecharacterizinganN-typewafer,thecurrentflowsfromthehotprobetowardsthecoldprobe.IfthewaferisP-type,currentflowsintheoppositedirection.RectificationMethod„4-pointprobe„HgprobeResistivityandResistance:„Resistivity(Ω-cm)„SheetResistance(Ω)„SeriesResistance(Ω)„ContactResistance(Ω)„SpreadingResistance(Ω)ResistivityandResistance:•Theresistivityintheingotisnotuniform.•Theresistivityofepitaxiallayersisuniform.•Resistivityaffectsdevices’seriesresistance,capacitance,thresholdvoltage,latch-upbehavior,breakdownvoltage,hotcarrierperformance.Resistivity(Ω-cm)Inaconductorwithauniformcrosssection,ρisdefinedas:ρ=RA/L(Ω-cm)ALρIsdeterminedbythematerialproperty,notrelatedtothedimensions.pnpqnqµµρ+=1Inasemiconductor,Sheetresistance„SheetresistancewhenL=WSeriesResistance(Ω)EpitaxyREpitaxyRSubstrateRSSubstrateSpreadingResistance(Ω)I2re-e-e-e-e-ThereisacomponentofCircuitresistanceduetotheconstrictionofthecurrentanditssubsequentspreadingwhencontactbetweenmacroscopicbodiesismadebymeansofmicroscopicareas.Two-pointarrangementshowingtheproberesistanceRp,thecontactresistanceRc,thespreadingresistanceRsp,andthesemiconductorresistanceRsCorrectionFactorsF1correctsforsamplethicknessF2correctsforlateralsampledimensionsF3correctsforthedistancebetweenprobeandsampleedgesFornon-conductingbottomForconductingbottomForts/2ForF2andF31Waferthicknesscorrectionfactorsversusnormalizedwaferthickness;tisthewaferthickness,stheprobespacing.Waferdiametercorrectionfactorsversusnormalizedwaferdiameter.ForcircularwafersD=waferdiameter;forrectangularsamplesD=samplewidth.Perpendiculartoanon-conductingboundaryParalleltoanon-conductingboundaryPerpendiculartoaconductingboundaryBoundaryproximitycorrectionfactorsversusnormalizeddistancedfromtheboundary.F31andF32arefornonconductingboundaries,F33andF34areforconductingboundaries.ParalleltoaconductingboundarySpreadingResistanceProbingProbingProblem:Clearbeveledgetodistinguishdifferentlayers;Bevelangle;stepincrement;probetip;calibration;ProbepenetrationProbeswillpenetrateultra-shallowjunctionsT.Clarysseet.al“Impactofprobepenetrationontheelectricalcharacterizationofsub-50nmprofiles”,J.Vac.Sci.Technol.B,Vol.20,No.1,Jan/Feb2002ErrorduetoprobepenetrationT.Clarysseet.al“Impactofprobepenetrationontheelectricalcharacterizationofsub-50nmprofiles”,J.Vac.Sci.Technol.B,Vol.20,No.1,Jan/Feb2002Fourpointprobemeasurement„Themostcommonmethodofmeasuringthewaferresistivityiswiththefour-pointprobe.„Measuringthecurrentthatflowsforagivenappliedvoltage.Usingfourprobesinsteadoftwoallowsustoforcethecurrentthroughthetwoouterprobes,wheretherewillstillbecontactresistanceandcurrentspreadingproblems,butwemeasurethevoltagedropwiththetwoinnerprobesusingahigh-impedancevoltmeter.Pr