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纳米材料和纳米结构第七讲.ppt

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第七讲PhysicalVaporDeposition(PVD)Application Coatingsofelectronicmaterials Insulator Semiconductor Conductor Superconductor Nanometerscalemultilayerstructures Advancedelectronicdevices AbrasionresistantcoatingsConcernedProblemsandChallenges Contaminationattheinterfacesorintermixing Multi-materialsystemsinvolved Costofequipmentandmaintenance Complexionofoperation SystemsDescribedinThisSection Sputtering Pulsedlaserdeposition 1Sputtering（溅射）1-1PrincipleofSputteringGlowDischargeMediuminSputteringChamber Agasoramixtureofdifferentgases,mostcommonlyArorHe Inreactivesputtering:introducereactivegasessuchasO2orN2 Pressure:afewmTorrtoseveralhundredsmTorr Procedure Generationofpositiveions:ionizingthesputteringgasbyglowdischarge Bombarding:acceleratedpositiveionstostrikethetargetsurfaceandremovemainlyneutralatoms Condensation:neutralatomsleavethetargetandcondenseonthesubstratesurface,andformintothinfilmsAnImportantConcept:SputteringYield Ameasurementoftheefficiencyofsputtering Ratioofthenumberofemittedparticlestothenumberofbombardingones1-2SputteringSystem用于制备TiN/VN多层膜的磁控溅射系统Waystoreducethedamageandre-sputteringofgrowingfilm Damagecausedbynegativeioneffectandradiationenhanceddiffusion Improvementmethod Usehighgaspressure:toreducetheenergyofthenegativeions Useoff-axissputtering:toavoidthesubstratedirectlyfacingthecathode Disadvantageofoff-axissputtering: lowdepositionrate smalldepositionarea Depositionofmagneticmaterials:facingtargetsputteringsystems正面溅射系统 示意图 Schematicofthefacingtargetsputteringsystem1-3PreparingMultilayerStructuresbySputteringBaTiO3NanolayerFerroelectricThinFilmCapacitors Advantage:higherrelativedielectricconstant Disadvantage:highleakagecurrent Electricalpropertiesstronglydependingupontheprocessingcondition,microcrystalstructure,andchoiceofbottomelectrode Amorphous:lowdielectricconstant(16at105V/cm),lowleakagecurrent Polycrystalline:highdielectricconstant(400at105V/cm),highleakagecurrent AimofnanolayerstructureBaTiO3filmcapacitor:highdielectricconstantandlowl