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1、Materialsevaluationofantireflectivecoatingsforsingle-layer193-nmlithographyRodenckR.KunzLincolnLaboratory,MassachusettsInstituteofTechnologyLexington,MA02173-9108RobertD.AllenIBM-AlmadenResearchCenterSanJose,CA95120ABSTRACTAsurveyofopticalconstantsfora
2、varietyofmaterialsmeasuredat193nmsuggeststhatantireflectionmeasureswillbenecessaryforsingle-layerresistlithographyat193nm.Theextenttowhichstandingwavesoccurin193-nmresistsissimilarinmagnitudetothoseoccurringat248nm.Tohelpreducetheseeffects,anewspin-ona
3、ntireflectivelayerhasbeendeveloped.Itiscomposedofapolymericdyeinaphase-compatibleblendwithatransparentbasepolymer,canbethermallycuredtorenderitinsoluble,andiscompatiblewithchemicallyamplifiedresists.Inadditiontothisspin-onmaterial,extensionofexisting24
4、8-nmdry-depositedantireflectivelayersto193nmshouldallowforeitherspin-onordry-depositedantireflectioncoatingsfor193-nmlithography.1.INTRODUCTIONProductionphotolithographyusing248-nmradiationcurrentlyfacesengineeringchallengeswhenpatterningnonplanarsubst
5、ratesduetononuniformitiesinthephotoresistlayerthickness.Thesedifficultiesstemfromthin-filminterferenceinthephotoresist.SeveralyearsagoBrunner1outlinedanumberofmethodsforreducingtheseeffects.Themethodsdescribedwereto(1)increasetheabsorptioncoefficientao
6、fthephotoresist,(2)useanantireflectivelayer(ARL)ontopofthephotoresist,(3)useanARLunderneaththephotoresist,(4)useamultiplewavelengthexposure,and(5)usehighnumericalapertureoptics.Fornonbleachingresistsusedinconjunctionwithmonochromatic(e.g.,laser-based)l
7、ightsources,methods(2)and(3)havebeenconsideredthemostpracticalapproachesforreducingtheeffectsofstandingwaves.Thefurtherextensionofproductionphotolithographyto193nm,whichisinitsearlystagesofdevelopment,2willsimilarlyrequiretheseARLapproachesforcertainli
8、thographylevels.Already,extensiveexperimentalandmodelingworkhasbeendoneat248nmtobetterunderstandrequirements,limitations,andperformanceofARLtechnology.3Thisframeworkwillhaveadirectbearingondevelopmentsat193nm,asmostofthemodelingcanbegen