57介绍各种暴光方式

1Lastmodified4/2/2004EECS217CNanotechnology©2004P.Burke1Fabrication•“Topdown”approachtonanotechnology•Thisisoverview,formoredetailstakeMAEcoursesbyMarcMadou,AndreShkel•ThankstoSungmuKangforINRFimages2Lastmodified4/2/2004EECS217CNanotechnology©2004P.Burke2PhotomasksDesigngeometryoncomputer.3Lastmodified4/2/2004EECS217CNanotechnology©2004P.Burke3MaskfabricationDarkroom(1/20reduction)transparencyAfterExposureDeveloperStopbathFixer4Lastmodified4/2/2004EECS217CNanotechnology©2004P.Burke4SpinonphotoresistPhotoresistspinnerwaferPhotoresist5Lastmodified4/2/2004EECS217CNanotechnology©2004P.Burke5SoftbakeOvenforsoftbakingofphotoresist(at90Cfor30min)6Lastmodified4/2/2004EECS217CNanotechnology©2004P.Burke6ExposetoUVlightMaskAlignerDevelopmentForShipley1827Water:MF351=5.5:1waferphotoresistmaskUVlightExposedregionsdissolvedindeveloperleavingbarewaferThisisthestepwhichlimitsthespatialresolution.7Lastmodified4/2/2004EECS217CNanotechnology©2004P.Burke7ThermalevaporationThermoevaporatorAluminacoatedWboatUsefulfore.g.Al,Ni,Au,Cr,Ti,NiCr,Pb,Sn8Lastmodified4/2/2004EECS217CNanotechnology©2004P.Burke8E-beamevaporationAuElectronbeamevaporator9Lastmodified4/2/2004EECS217CNanotechnology©2004P.Burke9LiftoffOpeningofphotoresistforTi/AugateAfterdepositionofTi/Au,thensoakinginacetone10Lastmodified4/2/2004EECS217CNanotechnology©2004P.Burke10Resolutionofopticallithography322zRλ=0.61RNAλ=ContactprintingProjectionprintingNAisnumericalaperture(typically0.5)zisresistthickness(typically0.1-1µm)11Lastmodified4/2/2004EECS217CNanotechnology©2004P.Burke11LightsourcesSourceλResolution•Hglamp(g-line)436nm400nm•Hglamp(i-line)365nm350nm•KrF248nm150nm•ArF193nm80nm•F2157nmresearchincreasingcostExtremeUV,x-raylithographyresearchtopics.Difficultieslieinsources,andmaterialsforopticsandmasks.12Lastmodified4/2/2004EECS217CNanotechnology©2004P.Burke12ElectronBeamLithography•Advantages–Resolution•electronwavelengthsmall•beamsize1nm•resolutionfromscatteringtypically10nm–Flexibility•Allpatternsundercomputercontrol•Disadvantages–Cost•Needhighvacuum•Needprecisionelectronfocusingmagnets–Throughput•Onlyonepixelexposedatatime•NotcommerciallyviableexceptforafewapplicationsInspiteofitsdisadvantages,e-beamlithographyisthemaintoolfornanotechnologyresearch.Reference:SPIEHandbookofMicrolithography,Micromachining,andMicrofabricationavailableat©2004P.Burke1314Lastmodified4/2/2004EECS217CNanotechnology©2004P.Burke1415Lastmodified4/2/2004EECS217CNanotechnology©2004P.Burke1516Lastmodified4/2/2004EECS217CNanotechnology©2004P.Burke16MolecularBeamEpitaxy(MBE)4atomperlayer!(FromStreetman,SolidStateElectronicDevices)17Lastmodified4/2/2004EECS217CNanotechnology©2004P.Burke17MBEepitaxialgrowthGaAsAlAsAlAs1.4eV2.2eVVzAlsoInP,InGaAs,InAlAs,InGaAsP…18Lastmodified4/2/2004EECS217CNanotechnology©2004P.Burke18Characterization•Opticalmicroscopycannotseebetterthanwavelengthoflight,~1µm•Scanningelectronmicroscope(SEM)•Transmissionelectronmicroscope(TEM)•Scanningprobemicroscopy(SPM)•Atomicforcemicroscope(AFM)19Lastmodified4/2/2004EECS217CNanotechnology©2004P.Burke19SEM•Advantages:–resolutionto1nm–fast–3dstructuresvisible–back-scatteredx-rayspectrumgivescompositionalinformation•Disadvantage–mustbeinvacuumenvironment(notgoodforbio)–expensive–samplesmustbeconductiveSeanLin,unpublishedSinglewalledcarbonnanotubes,ShengdongLi,submitted20Lastmodified4/2/2004EECS217CNanotechnology©2004P.Burke20TEM•Advantages–resolution1nm–fast–diffractionpatterngivescrystolographicinfo•Disadvantages–expensive–highvacuum–samplemustbethinnedShengdongLi,submittedMultiwalledcarbonnanotube21Lastmodified4/2/2004EECS217CNanotechnology©2004P.Burke21SPM/AFM•Modeofoperation–non-contact–tunneling•Advantages–worksinairorliquid–angstromresolutionpossible–canimageindividualatoms–probesvariousquantities•conductance•magnetism•Disadvantages–extremelyslow–manyminutesforoneimageShengdongLi,unpublished22Lastmodified4/2/2004EECS217CNanotechnology©2004P.Burke22Lengthscales•Atoms–~angstrom10-10m•Light–wavelength~µm•Electrons–DeBrogliewavelength=h/p(quantummechanics)–=sqrt(150/V)inangstroms(Visenergyinvolts)–~0.1-10nm–Ifananoelectroniccircuitelementisaboutthesizeofanelectronwavelength,wavenaturewillbecrucial–Conductancequantizedatthesesmallscalesinunitsofe2/h•Meanfreepath(MFP)–10-10minmetalsatroomtemperature–10-4minultrahighqualitysemiconductorsatlowtemperatures23Lastmodified4/2/2004EECS217CNanotechnology©2004P.Burke23Energies•Electronictransistionenergies–~1-10eV•Fermienergy–1-10eVinmetals–1-10meVinsemiconductors•kT–30meVatroomtemperature