国际会议海报Poster模板

Scanningnear-fieldopticallithography(SNOL)oforganicsemiconductorsDanCredgington1,OliverFenwick1,AnaCharas2,JorgeMorgado2,KlausSuhling3andFrancoCacialli11UCLDepartmentofPhysicsandAstronomyandLondonCentreforNanotechnology,17-19GordonStreet,LondonWC1H0AH,UK.2InstitutodeTelecomunicações,InstitutoSuperiorTécnico,Av.RoviscoPais1,P-1049-001Lisboa,Portugal.3DepartmentofPhysics,King’sCollegeLondon,TheStrand,LondonWC2R2LS,UK.Scanningnear-fieldopticallithography(SNOL)hasbeenshowntoprovideaversatilemethodforpatterningmaterialsoverlengthswellbelowtheclassicaldiffractionlimit.Weapplythistechniquethinfilmsoforganicsemiconductors.Theseopticallyandelectronicallyactivematerialsarechemicallytuneable,flexible,andcanoftenbeprocesseddirectlyfromsolution.Forapplicationsinphotonicdevicesandnano-electronics,achievinglithographicresolutiononthenano-scaleisvital.Usingahome-builtSNOLsystem,wedemonstratehowthinfilmsofthewidelystudiedpolymerpoly(para-phenylene-vinylene)(PPV),andthecross-linkableoxetanederivativesF8OxandBTOxcanbepatternedtoanypredetermineddesign.•TheSNOLprobe:asharpened,metal-coatedopticalfibrewithasub-wavelengthaperturedefinedattheapex•325nmHeCdlaserlaunchedintothefibre.•Opticalnear-fieldgeneratedaroundtheaperture•Contactismaintainedusingshear-forcefeedbackINSUMMARY,scanningnear-fieldopticallithographyisapowerfultoolforpatterningmaterialsonthenano-scale.Wehaveinvestigatedtheresolutionachievablewithoursystem,asappliedtothepatterningofPPV,andfoundthatafeaturesizeofaround50nmarepossible.Wehavealsoshownthat,inadditiontoindividualsmallstructures,creatinglargearraysandmorecomplicateddesignsisequallyfeasibleusingSNOL.Finally,wehaveshownthatavarietyofothermaterialsaresuitableforpatterningviathistechnique,includingBTOxandF8Ox,whichundergoaverydifferentreactiontoPPV.-505100100200300400nmnm-50510nm60nm75nmAB200nmBA10µm1µm(Left)AFMscanofafeaturesdrawninPPVonavarietyoflengthscales,froma~15nmthickprecursorfilmusinga50nmnear-fieldprobe.5µmXBTOxr-BTOxUVactivation-5005010015020001234567891011µmnmX~500nmPhotoinitiator•Cross-linkingthroughoxetaneside-chainsactivatedviaaphotoacidinitiator.•Cross-linkedreticulatednetwork(r-BTOx)forms.•DevelopmentinTHFremovestheunexposedpolymer.Sub-wavelengthapertureIncidentlaserLog(Intensity)Thinfilm(Right)3-dimensionalrepresentationoftheopticalfieldstrengthinathinfilmplacedbelowthetipofanaperturedSNOLprobe.OpticalintensitydistributioniscalculatedwiththeBethe-Bouwkampmodel(λ=325nm,aperturediameter50nm,filmthickness20nmandfilmrefractiveindex1.73+0.067i.)PPVBTOxSNOLOpticalfibreprobeQuartztuningforkSampleContactsProbetipxzyAcopolymerbasedaroundthecommongreen-emittingpolymerF8BT.(Right,bottom)crosssectionthroughthepillars,typicalfeaturesizeofaround500nm.PPVstructuresfabricatedviaaWessling-typeprecursorprocessusingSNOLtoconvertpoly(p-xylenetetrahydrothiopheniumchloride)(PXT)in-situintoconjugatedPPV.UnexposedPXTremovedusingmethanolPXTUVactivationPPV(Right,top)Anarrayofpillarsdefinedinr-BTOxfroma200nmfilmusinga60nmprobeapertureUnbakedHeight(nm)01020304050BakedHeight(nm)010203040Sample1Sample2Sample3Sample4Sample5UnbakedFWHM(nm)0100200300400BakedFWHM(nm)0100200300Sample1Sample2Sample3Sample4Sample5(Below)Cross-sectionsofthefinestfeatures.5µm200nmX0246810050100150200nmnmX55nm(Left)DotsdrawninPPVfroma15nmfilm,usinga50nmprobeaperture.(Right)Zoomandcross-sectionthroughthisfeatureshowingFWHMofapproximately55nm.100502005001000Exposuretime(ms)•Structureof65,000pixels.•Minimumresolution60nm.→Integrityofaperturemaintained.Non-uniformshrinkageduringbaking•Uniformfilmsshrink~50%duringbaking.•Heightandwidthofnano-sizeddotsmeasuredbeforeandafterbakingLinearfitstodatagive:nmWWubb46nmHHubb37.0W=width(FWHM)H=heightb=bakedub=unbaked→30%verticalshrinkage→Outerlayerscollapseafixed20-25nmaroundtheedge(notdependentonlateraldimension)Poly{2,7-(9,9-dioctylfluorene-alt-benzothiadiazole)-co-1,4-(2,5-bis-(methyl-4’-(6-(3-methyloxetan-3-yl)methoxy)hexyloxy)benzene)}F8Ox•Oxetanesidechains(analoguetoBTOx).•Blue-emitting.•Photoluminescencepreservedduringlithography.•Under-exposureresultsinpoorlypositionedfeatures(areaC).(Left)Arraysofpillarsdefinedinr-F8Oxfroma~200nmfilmusinga60nmprobeaperture.ExposuredecreasesfromA(200ms)toB(50ms)toC(20ms).(Right)Confocalphotoluminescenceimagesofthesameareas.Wethank:theEPSRC;theRS;theECforfundingoftheRTNTHREADMILL(EU-contract:MRTN-CT-2006-036040);theEuropeanScienceFoundationEUROCORESProgrammeSONSwithsupplementaryfundsfromEPSRCandtheECSixthFrameworkProgramme(ERAS-CT-2003-980409);aswellastheECSeventhFrameworkProgramme(FP7/2007-2013)undergrantagreementN.212311(ONE-P).