纳米材料和纳米结构第七讲-new-2-PVD.ppt

纳米材料和纳米结构第七讲-new-2-PVD.ppt

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第七讲第七讲第七讲第七讲PhysicalVaporDeposition物理气相沉积物理气相沉积纳米材料和纳米结构纳米材料和纳米结构纳米材料和纳米结构纳米材料和纳米结构PhysicalVaporDeposition（PVD）wDefinitionDepositionoffilmsbycondensationfromvaporphaseiscommonlycalledphysicalvapordeposition（PVD）.wThreeStepsofPVDGeneratingavaporphasebyevaporationorsublimationwElectron-beamevaporation（电子束蒸发）（电子束蒸发）wMolecular-beamepitaxy（分子束外延（分子束外延,MBE）wThermalevaporation（热蒸发）（热蒸发）wSputtering（溅射）（溅射）wCathodicarcplasmadeposition（阴极电弧等离子体沉积）（阴极电弧等离子体沉积）wPulsedlaserdeposition（脉冲激光沉积）（脉冲激光沉积）TransportingthematerialfromthesourcetothesubstrateFormationoffilmbynucleationanddiffusionwApplicationIncoatingsofelectronicmaterialswInsulatorwSemiconductorwConductorwSuperconductorNanometerscalemultilayerstructureswAdvancedelectronicdeviceswAbrasionresistant（抗磨）抗磨）coatingswConcernedProblemsandChallengesContaminationattheinterfacesorintermixingMulti-materialsystemsinvolvedCostofequipmentandmaintenanceComplexionofoperationwSystemsDescribedinThisSectionSputteringPulsedlaserdeposition1Sputtering（溅射）（溅射）1-1PrincipleofSputtering1-2SputteringSystem1-3PreparingMultilayerStructuresbySputtering1-4CurrentStatusofSputtering1-1PrincipleofSputteringwEjection（喷射）（喷射）ofAtomsfromtheTargetAccomplishedbyanenergeticparticlebombardingatargetsurfacewithsufficientenergy（50eV1000eV）wTargetCathodeConnectedtoanegativevoltagesupplyComposedofthematerialstobedepositedwSubstrateAnodeMaybegrounded,floated,orbiasedwGlowDischargeMediuminSputteringChamberAgasoramixtureofdifferentgases,mostcommonlyArorHeInreactivesputtering:

introducereactivegasessuchasO2orN2Pressure:

afewmTorrtoseveralhundredsmTorrwProcedureGenerationofpositiveions:

ionizingthesputteringgasbyglowdischargeBombarding:

acceleratedpositiveionsstrikethetargetsurfaceandremovemainlyneutralatomsCondensation:

neutralatomsleavethetargetandcondenseonthesubstratesurface,andformintothinfilmswAnImportantConcept:

SputteringYieldAmeasurementoftheefficiencyofsputteringRatioofthenumberofemittedparticlestothenumberofbombardingones1-2SputteringSystemwTypicalTypesofSputteringSystemsDirectcurrent（dc）diodesputteringwUsedforsputteringconductingmaterialsRadiofrequency（rf）diodesputteringwUsedforsputteringinsulatingmaterialsMagnetrondiodesputteringwMostcommonlyusedtodaywPlasmabeconfinedaroundthetargetsurfacebyamagnetfieldwAdvantagesofusingmagnetronsputteringlFeasibilityoflargecathodesizelHighsputteringyieldlLessbombardmenttothesubstrate用用于于制制备备TiN/VN多多层层膜膜的的磁磁控控溅溅射射系系统统氩气氩气流量表流量表流量控制阀流量控制阀压力传感器压力传感器低温泵低温泵低温泵低温泵靶靶1靶靶2旋转衬底支架旋转衬底支架衬底衬底流量表流量表阀门阀门流量表流量表流量控制阀流量控制阀1流量控制阀流量控制阀2主流量控制阀主流量控制阀质谱仪质谱仪阀门阀门锁定装置锁定装置wWaystoreducethedamageandresputteringofgrowingfilmDamagecausedbynegativeioneffectandradiationenhanceddiffusionImprovementmethodwUsehighgaspressure:

toreducetheenergyofthenegativeionswUseoff-axissputtering:

toavoidthesubstratedirectlyfacingthecathodewDisadvantageofoff-axissputtering:

llowdepositionratelsmalldepositionareawDepositionofmagneticmaterials:

facingtargetsputteringsystems偏轴溅射系统偏轴溅射系统示意图示意图Schematicofoff-axissputteringsystem可可360度旋转的衬底支架度旋转的衬底支架陶瓷加热器陶瓷加热器负离子撞击区负离子撞击区衬底衬底靶靶溅射枪溅射枪溅射源溅射源屏蔽闸屏蔽闸空间屏蔽区空间屏蔽区正面溅射正面溅射系统系统示意图示意图Schematicofthefacingtargetsputteringsystem衬底衬底靶靶磁体磁体冷却水冷却水氩气氩气1-3PreparingMultilayerStructuresbySputteringwTypesandPropertiesofMultilayerStructuresTypesofarchitectureswMetal/metalwCeramic/ceramicwMetal/ceramicwSemiconductor/semiconductorPropertieswWithstructurallymodulatedarchitectureswWithcompositionallymodulatedarchitectureswHighinterfacevolumefractionwLargeintrinsicstresswWithstructuraland/orcompositionalgradientwExhibitinguniqueandenhancedelectric,dielectric,magnetic,andmechanicpropertieswBaTiO3NanolayerFerroelectricThinFilmCapacitorsAdvantage:

higherrelativedielectricconstantDisadvantage:

highleakagecurrentElectricalpropertiesstronglydependingupontheprocessingcondition,microcrystalstructure,andchoiceofbottomelectrodewAmorphous:

lowdielectricconstant（16at105V/cm）,lowleakagecurrentwPolycrystalline:

highdielectricconstant（400at105V/cm）,highleakagecurrentAimofnanolayerstructureBaTiO3filmcapacitor:

highdielectricconstantandlowleakagecurrentRealizationandeffectsuSubstrate:

Ru/SiO2/SiuTechnique:

rfmagnetronsputtering,sputteringinterruption（中中断断）betweenlayerstochangethesubstratetemperatures（680C,60C）uLayerstructure:

n-cyclealternatelayersofamorphousandpolycrystallineBaTiO3（microcrystallinebeobtainedbyannealingamorphouslayer）uResultsobtainedlLeakagecurrentdensitybeconsiderablyreduced,andtheeffectbecomingbetterwithincreasingcyclenumberlDielectricconstantbetwoorthreetimeshigherthansingleamorphouslayerbutlowerthanasinglepolycrystallinelayer具有纳米多层结构的具有纳米多层结构的BaTiO