外文翻译--微模具制造中聚焦离子束技术的调查 英文版.pdf

MicroelectronicEngineering56(2001)333338Investigationofmicrolensmoldfabricatedbyfocusedionbeamtechnology*Y.FuPrecisionEngineeringandNanotechnologyCenter,SchoolofMechanicalandProductionEngineering,NanyangTechnologicalUniversity,NanyangAvenue,Singapore639798,SingaporeAccepted25April2001AbstractAnovelfabricationmethodofmicrolensmold,focusedionbeam(FIB)milling,ispresentedinthispaper.Substrateswithdifferentmaterials,copper,nickel,andbulksilicon,wereusedinordertocomparetheirmillingquality.Two-dimensionalprofilesandsurfaceroughnessofthefabricatedmoldsweremeasuredusingalaserinterferometer.Finally,themoldwasusedforhotembossingreplication.Thesurfaceroughness(Rvalue)ofthereplicaisabout8nm,andtheprofileisneatandasymmetric.Measuredsizesofthereplicacoincidewellwiththatofthedesign.Keywords:Microlensmold；FIBmilling；Hotembossing；Replication1.IntroductionConventionalfabricationmethodsofmoldingformicrolensandopticalcomponentsarelithographypatterningandelectroplating16.Fabricationerrorislargeduetoaccumulatederrorduringmanyprocedures.Anovelmicromachiningmethodformicrolensmolding,focusedionbeammilling,ispresentedinthispaper.Comparedwithconventionalmethods,ithasthefollowingadvantages:itisaone-stepmachining,andnootherproceduresareneeded,thereforemanufacturingerrorislessthanthatoftheconventionalmethods；thematerialofthemoldcanbeglass,silicon,metalorothernon-metal；machiningaccuracycanbecontrolledeasierusingcomputerprogrammingduringthemillingprocess.Substrateswithdifferentmaterials,copper,nickelandbulksilicon,wereusedtocomparetheirmilling*Tel.:165-790-6875；fax:165-791-1859.E-mailaddress:.sg(Y.Fu).334Y.Fu/MicroelectronicEngineering56(2001)333338quality.Experimentalresultsofthereplicationbyhotembossingforthemicrolensarepresentedinthispaper.2.MoldmicrofabricationusingFIBmillingThemillingexperimentswerecarriedoutusingourfocusedionbeam(FIB)machine(Micrion9500EX)withtheliquidgalliumionsourceintegratedwithscanningelectronmicroscopy(SEM),energydispersionX-rayspectrometry(EDX)facilitiesandgas-assistedetching(GAE)functions.This1equipmentusesafocusedGaionbeamwithenergybetween5and50keV,aprobecurrentbetween4pAand19.7nAandabeam-limitingaperturesizebetween25and350mm.Forthesmallestbeamcurrents,thebeamcanbefocuseddownto7nmindiameteratfullwidthandhalfmagnitude(FWHM).Themicrolensmoldisdesignedwithdiameterof70mm,adepthof3.45mm,aradiuscurvatureof180mmandsphericalform.Themoldmillingprocessiscontrolledbyacomputerprogram,inwhichtheparametersofmachiningandthemoldwereset.FabricationprocesswasintroducedindetailinRefs.710.Inordertostudythemoldmillingperformancefordifferentmaterials,substratesofnickel,copperandbulksiliconwereusedfortrials.Afterfinishingthemold,hotembossingwascarriedoutusingapressuremachinewithaheatingandthermalcontrolsystem,withPolycarbonate2800(Bayer).Themoldingwascompletedunderthefollowingconditions:temperature,3408F；pressure,2000lb(|8.8kN).3.ExperimentalresultsanddiscussionDesignedmicrolensparametersareasfollows:diameter,70mm；sagheight,3.45mm；NAvalue,0.1；workingunderwavelengthof633mm.Fig.1showsthemicrolensmoldmanufacturedbyFIBmillingonthesubstratewithcopper.Fig.2showsthetwo-dimensionalprofileofthemoldmeasuredusingtheWYKONT2000laserinterferometer.Itcanbeseenthatthesurfaceofthemoldisnotsmooth,withsomedefectsononesideofthemold.Thetwo-dimensionalprofileshowsthatthesurfaceofthemoldisveryrough,andFig.1.Microlensmoldwithcoppermaterial,milledbyFIB.Y.Fu/MicroelectronicEngineering56(2001)333338335Fig.2.CoppermoldprofilemeasuredbytheWYKONT2000laserinterferometer.theformisirregular.Figs.3and4showmillingandmeasuringresultsforthemoldwithnickelmaterial.Ascanbeseen,theresultsarenotideal,andsimilartothepreviouscase.Figs.5and6showmillingandmeasuringresultsforthemoldwithbulksilicon.Itcanbeseenthatthemillingresultisidealwithasmoothsurface,andaneatandsymmetricprofile.ThemeasuredsurfaceroughnessRvalueis2.5nm.Fig.7showsascanningelectronmicroscope(SEM)amicrographofa636microlensmoldarraymilledbyFIBonbulksilicon.Itstwo-dimensionalprofiledatameasuredbytheinterferometeristransferredinordertocomparewiththedesignedprofile,asshowninFig.8.Ascanbeseen,thesetwoprofilescoincidewell.Itcanbeseenthatthemoldqualityforbulksiliconisbetterthanthemetalmaterials.ThepossiblereasonisthatthemillingprocessisapurephysicalcollisionprocessbetweenpositiveionsandmetalFig.3.MicrolensmoldwithnickelmaterialmilledbyFIB.Fig.4.NickelmicrolensmoldprofilemeasuredbytheWYKONT2000laserinterferometer.336Y.Fu/MicroelectronicEngineering56(2001)333338Fig.5.MicrolensmoldmilledbyFIBonbulksiliconm