Thin-Film-Deposition薄膜沉积技术

ThinFilmDeposition薄膜沉积NANO-MASTER那诺-马斯特中国有限公司吴运祥2017年8月16日PhysicalVaporDeposition(PVD)-Filmisformedbyatomsdirectlytransportedfromsourcetothesubstratethroughgasphase•Evaporation•Thermalevaporation«•E-beamevaporation«•Sputtering•DCsputtering«•DCMagnetronsputtering«•RFsputtering«•ReactivePVDChemicalVaporDeposition(CVD)-Filmisformedbychemicalreactiononthesurfaceofsubstrate•Low-PressureCVD(LPCVD)«•Plasma-EnhancedCVD(PECVD)«•Atmosphere-PressureCVD(APCVD)•Metal-OrganicCVD(MOCVD)OxidationSpinCoatingPlatting•DepositionRate•FilmUniformity•Acrosswaferuniformity•Run-to-rununiformity•Materialsthatcanbedeposited•Metal•Dielectric•Polymer•QualityofFilm–PhysicalandChemicalProperties•Stress•Adhesion•Stoichiometry•Filmdensity,pinholedensity•Grainsize,boundaryproperty,andorientation•Breakdownvoltage•Impuritylevel•DepositionDirectionality•Directional:goodforlift-off,trenchfilling•Non-directional:goodforstepcoverage•Costofownershipandoperation¨Loadthesourcematerial-to-be-deposited(evaporant)intothecontainer(crucible)¨Heatthesourcetohightemperature¨Sourcematerialevaporates¨EvaporantvaportransportstoandImpingesonthesurfaceofthesubstrate¨EvaporantcondensesonandisadsorbedbythesurfaceCrucible(energysource)CurrentEvaporantVaporFilmSubstrateMassDepositionRateperunitareaofsourcesurface:()PTPrTMCRemm−=)(1coscos221ϕθθϕrePPSubstrateCm=1.85x10-2r:source-substratedistance(cm)T:sourcetemperature(K)Pe:evaporantvaporpressure(torr),functionofTP:chamberpressure(torr)M:evaporantgram-molecularmass(g)Source(K-Cell)¬Maximumdepositionratereachesathighchambervacuum(P~0)SphericalSurfaceSphericalsurfacewithsourceonitsedge:θϕrePP0r02coscosrr==ϕθ20214rPTMCRemm=¨AngleIndependent–uniformcoating!Source(K-Cell)¬UsedtocoatinstrumentswithsphericalsurfacesConsiderthedepositionratedifferencebetweenwafercenterandedge:θϕePPWafer1r2r2/W2111rR∝42212222cos1rrrR=∝θDefineUniformity:()()%%121RRR−=σ2122212211rWrW≈+−=−σσ21=rWorSource(K-Cell)0204060801001201401600246810SampleSize(W)Source-SampleDistance(r)1%2%5%10%Source-substratedistancerequirement:Inpractice,itistypicaltodoublethisnumbertogivesomeprocessmargin:σ2Wrσ2WrLargerrMeans:¬biggerchamber¬highercapacityvacuumpump¬lowerdepositionrate¬higherevaporantwasteAnotherCommonSolution:off-axisrotationofthesampleemARdtdhρ=θϕrePPSource(K-Cell)SubstrateTdhFilmAeThicknessdepositionrate()TPrTMCAdtdheme2211coscosϕθρ=T:sourcetemperature(K)Ae:sourcesurfacearea(cm2)ρ:evaporantdensity(g/cm3)PeisfunctionofsourceTemperature!Example:AlM~27,ρ~2.7,Ae~10-2cm2,T~900KR~50cm(uniformityrequirement)ePdtdh50=(A/s)¬Thehigherthevaporpressure,thehigherthematerial’sdepositionrateTypicallyfordifferentmaterial:)/()()100~10(sATPdtdhe=•Fordepositionrate1A/s:Pe~100mtorr•Pedependson:1)materilaand2)temperature•Depositionratesaresignificantlydifferentfordifferentmaterials•Hardtodepositmulti-component(alloy)filmwithoutlosingstoichiometryExample:forPe100mtoorT(Al)1400K,T(Ta)2500KCrucibleResistiveWireCurrentSourceMaterialFoilDimpleBoatAluminaCoatedFoilDimpleBoatContaminationProblemwithThermalEvaporationContainermaterialalsoevaporates,whichcontaminatesthedepositedfilmCrCoatedTungstenRode-MagneticField(beamfocusing&positioning)EvaporantEvaporantCrucibleCathodeFilamentFocusingApertureElectronBeamWaterCooledRotaryCopperHearth(SequentialDeposition)AdvantageofE-BeamEvaporation:VerylowcontainercontaminationHigh~3000ºC10~100A/sLowEverythingabove,plus:Ni,Pt,Ir,Rh,Ti,V,Zr,W,Ta,MoAl2O3,SiO,SiO2,SnO2,TiO2,ZrO2BothmetalanddielectricsE-BeamLow~1800ºC1~20A/sHighAu,Ag,Al,Cr,Sn,Sb,Ge,In,Mg,GaCdS,PbS,CdSe,NaCl,KCl,AgCl,MgF2,CaF2,PbCl2Metalorlowmelt-pointmaterialsThermalCostTemperatureRangeDepositionRateImpurityTypicalEvaporantMaterialDepositionStoichiometricalProblemofEvaporation•Compoundmaterialbreaksdownathightemperature•Eachcomponenthasdifferentvaporpressure,thereforedifferentdepositionrate,resultinginafilmwithdifferentstoichiometrycomparedtothesource16002500BoronNitride(BN)19002030Alumina(Al2O3)26003799GraphiticCarbon(C)RefractoryCeramics25302620Molybdenum(Mo)30603000Tantalum(Ta)32303380Tungsten(W)Temperaturefor10-mtorrVaporPressure(Pe)(ºC)MeltingPoint(ºC)MaterialRefractoryMetalsSubstrate(Anode)2–5kVe-Target(Cathode)e-e-γArArAr+•Target(source)andsubstrateareplacedontwoparallelelectrodes(diode)•Theyareplacedinsideachamberfilledwithinertgas(Ar)•DCvoltage(~kV)isappliedtothediode•Freeelectroninthechamberareacceleratedbythee-field•TheseenergeticfreeelectronsinelasticallycollidewithAratoms’excitationofAr¨gasglows’ionizationofAr¨Ar++2ndelectron•2ndelectronsrepeataboveprocess¨“gasbreakdown”¨dischargeglow(plasma)•Nearthecathode,electronsmovemuchfasterthanionsbecauseofsmallermass¬positivechargebuildupnearthecathode,raisingthepotentialofplasma¬lesselectronscollidewithAr¬fewcollisionwiththesehighenergeticelectronsresultsinmostlyionization,ratherthanexcitation¬darkzone(CrookesDarkSpace)•Dischargecausesvoltagebetweentheelectrodesreducedfrom~103Vto~102V,mainlyacrossthedarkspace•Electricalfieldinotherareaissignificantlyreducedbyscreeningeffectoftheposi