EM397ThinFilmMechanics–1.IntroductionEM397ThinFilmMechanicsI.IntroductionNanshuLu,Ph.D.UniversityofTexasatAustinFall2013EM397ThinFilmMechanics–1.IntroductionThinFilmsinNatureEM397ThinFilmMechanics–1.IntroductionThinFilmsinAdvancedTechnologiesPlasticPolyimideWheatstoneBridgediodeSiO2MetalSU8MetalSU85mm200µm3EM397ThinFilmMechanics–1.IntroductionApplicationsofThinFilms•Nature:tectonicplates,leavesandpetals,humanskin,cellmembranes,etc.•Electronics:semiconductors,interconnects,dielectrics•Optics:LEDsandphotodetectors,photonics•Energy:photovoltaics,batteriesandsupercapacitors,piezoelectricnanogenerators•Electromechanicalsystems:MEMS/NEMS,electroactivethinfilmpolymeractuators•Surfacecoatings:thermal,mechanical,tribological,hydrophobicenvironmental,optical,magnetic,orbiologicalfunctions4EM397ThinFilmMechanics–1.IntroductionHowThinis“Thin”•Geometry•Microstructures•Atomic/molecularstructures•Microstructurallythinfilms:Cufilmsininterconnects•Atomicallythinfilms:graphene,h-BN,MoS2•Mechanicallythinfilms:tectonicplates,humanskins,coatings5lwhshfhfhsl,wEM397ThinFilmMechanics–1.IntroductionThinFilmMechanics•Generationandevolutionofstressinfilms•Consequenceofstress:deformation,wrinkling/buckling,rupture,delamination•Couplingbetweenstressandnon-mechanicaleffects•Measurementoffilmstress•Characterizationofmechanicalbehavior•Predict/preventfailure•Reliabilityanalysisanddesign6EM397ThinFilmMechanics–1.IntroductionTopicsinEM397•Introductiontothinfilmprocesses:depositionmethods,growthmodes,microstructures•Stressinthinfilms:growthstress,epitaxialstress,Stoneyformula,wafercurvature,multilayerstack•Fractureanddelamination:channelingcracks,interfacedebonding•Filmbuckling:buckle-delamination,bucklingwithoutdelamination(wrinkling),pressurizedbulge•Flexibilityandstretchability:film-substrateinteraction,failuremodes,enhancement•2Dmaterials:mechanicalproperties,structure-propertyrelationships,processinganddevicemechanics•Electromechanicalcoupling:piezoresistiveandpiezoelectricthinfilms•Plasticityanddislocations:strengthandhardening,dislocationformationandinteractions•Diffusionandcreep:grain-boundarydiffusion,interfacediffusion,deformationmechanisms•Chemomechanicalcoupling:thinfilmelectrodesofLi-ionbatteries7