材料期刊网

Photorefractive Effect in an Azobenzene Chromophore Side Groups Polymer

FANG Hua , LI Mingtian

武汉理工大学学报-材料科学版(英文版) doi:10.1007/s11595-014-1083-4

关键词:

NiO/FeCo磁性多层膜的高频磁性

李玉伟 , 陈继红 , 唐东明 , 张豹山 , 鹿牧 , 陆怀先

功能材料与器件学报 doi:10.3969/j.issn.1007-4252.2010.02.011

制备了一系列具有铁磁/反铁磁交换偏置作用的[NiO/Fe65Co35]10多层膜,使用振动样品磁强计(VSM)测量了样品的静磁参数,利用微带线法测量了样品4GHz-10GHz的磁谱,首次制备并测得了自然共振频率(fr)在6GHz以上,最高到f=9.6GHz的薄膜样品.结果表明交换偏置场(Hex)、各向异性场(Hua)、以及矫顽力(Hc)随铁磁层厚度(tFM)增大而减小;基于Landau-Lifishitz (L-L)方程对静磁参量和磁谱进行了比较,发现样品自然共振频率较L-L方程计算值偏大30%以上.

关键词: 铁磁 , 反铁磁 , 交换偏置场 , 各向异性场 , 交换耦合能密度 , 自然共振频率

New criteria of glass forming ability, thermal stability and characteristic temperatures for various bulk metallic glass systems

Materials Science and Engineering a-Structural Materials Properties Microstructure and Processing

Six mathematical criteria used for quantitatively measuring their glass forming ability, thermal stability and characteristic temperatures (temperature of glass transition T-g, crystallization onset T-x and liquidus T-l) of various bulk metallic glasses (BMGs) have been proposed in this article. It is found that the criteria are suitable for evaluating these quantities for BMGs. The estimated results are better than those calculated by Fang et al.'s models and Lu et al.'s gamma criterion, but our analyses indicate that these criteria, defined by the data (Pauling electronegativity xi, atomic radius ri, electron concentration ni and melting temperature T-mi) easily found in literatures, still need to be further refined in future research for shortcomings of the parameters. (C) 2007 Elsevier B.V. All rights reserved.

关键词: bulk metallic glasses;glass forming ability;thermal stability;supercooled liquid regions;mechanical-properties;amorphous-alloys;transition temperature;bond parameters;strength;binary;widths;ag

ATOMIC FORCE MICROSCOPY OBSERVATION OF MAGNETRON SPUTTERED ALUMINUM-SILICON ALLOY FILMS

金属学报(英文版)

粒裕希停桑谩。疲希遥茫拧。停桑茫遥希樱茫希校佟。希拢樱牛遥郑粒裕桑希巍。希啤。停粒牵危牛裕遥希巍。樱校眨裕裕牛遥牛摹。粒蹋眨停桑危眨停樱桑蹋桑茫希巍。粒蹋蹋希佟。疲桑蹋停?##2##3##4##5ATOMICFORCEMICROSCOPYOBSERVATIONOFMAGNETRONSPUTTEREDALUMINUM-SILICONALLOYFILMSJ.W.Wu,J.H.FangandZ.H.Lu(NationalLaboratoryofMoleculeandBiomoleculeElectronics,SoutheastUniversity,Nanjing210096,ChinaManuscriptreceived27October1995)Abstrcat:Twodifferentsurfacemorphologycharacteristicsofmagnetronsputteredaluminumsilicon(Al-Si)alloyfilmsdepositedat0and200℃wereobservedbyatomicforcemicroscopy(AFM).Oneisirregularlyshapedgrainsputtogtheronaplane.TheotherisirregularlyshapedgrainsPiledupinspace.Nanometer-sizedparticleswithheightsfrom1.6to2.9nmwerefirstobserved.Onthebasisoftheseobservationsthegrowthmechanismofmagnetronsputteredfilmsisdiscussed.Keywords:magnetronsputtering,Al-Sialloy,surfacemorphology,atomicforcemicroscopy,filmgrowthmechanism1.IntroductionTheuseofaluminumalloys[1,2],inparticularAl-Si,isacommonfeatureinmanysinglelevelandmultilevelinterconnectionschemesadoptedinthemanufactureofmicroelectronicdevicesbecauseofseveraldesirableproperties.TheAl-Sigrainmorphology(size.geometryanddistributionofgrainsisassociatedwithstepcoverage[3],electromigration[4]andinterconnectsresistivity[5]etc..Thus,characterizationofAl-Sialloysurfacemorphologyisveryimportant,especiallywhenintegratedintensityincreasesandlinewidthsof0.3to0.5μmbecomecommon.Inthepasttwentyyears,theAl-Sialloysurfacemorphologywhichaffectsthereliabilityofmicroelectronicdeviceshasbeenwidelyinvestigatedbyscanningelectronmicroscopy(SEM),transmissionelectronmicroscopy(TEM)etc.[5-7].However,SEMandTEMhavetheirlimitationorinconvenience,forexample,theverticalresolutionofSEMisnothighandTEMneedscomplexsamplepreparation.Recently,anewgrainboundaryetchingmethodwasproposed￣[8]whichalsoneedstroublesomechemicaletching.Atomicforcemicroscopy(AFM),sinceitsemerging,hasbecomemoreandmoreusefulinphysics,chemistry,materialsscienceandsurfacescience,becauseofitshighresolution,easeofsamplepreparationandrealsurfacetopography.Recently,discussion[9,10]waspresentedonhowAFMwillplayaroleinsemiconductorindustry.Asaresponsetothisdiscussion,weusedAFMtoinvestigateAl-SialloysurfacemorphologyandhaveobtainedsomeresultswhichcannotberevealedbySEMorTEM.ThisindicatesthatAFMisagoodcharacterizationtoolinsemiconductorindustry.2.SamplePreparationInourexperiments,aluminumwith30ppmsiliconwassputteredonsiliconsubstrateinbatchdepositionmodeAllthreefilmswiththicknessof1.6μmweredepositedusinganargonsputteringpressureof4.2×10￣-3Pa.TheotherdepositionparametersaredescribedinTable1.Thesubstratewascleanedusingstandardpremetallizationcleaningtechniquespriortofilmdeposition.3.ExperimentalResultsandDiscussionTheAFMmeasurementswereperformedonacommercialsystem(NanoscopeIII,DigitalInstruments,SantaBarbara).Thetipismadeofmicrofabricatedsiliconnitride(Si_3N_4)Itisattachedtoa200μmcantileverwithaforceconstantofabout0.12N/m.Beforethesurfaceofsamplewasexamined.agoodtipwithananometer-sizedprotrusionatitsendwasselectedbeforehand,whichcanbeobtainedbyimagingtheatomicstructureofmicasubstrateandagoldgrid.AtypicaloperatingforcebetweenthetipandAl-Sisamplesurfaceisoftheorderof10￣-8Nandallimagesweretakenatroomtemperatureinair.AtypicaltopographicviewoftheAl-SifilmsisshowninFig.1(allimagescansizeis5by5μma,bandcarerespectivelyforsample1,2,and3).FromFig.la,itcanbeseenthatirregularlyshapedgrainstiltinginvaryingdegreespileupinspace,andgroovesamongtheirregularlyshapedgrainsaredifficulttodecideatacertainarea(wedefineitascharacteristicA).Toourknowledge,onreportsonthesurfacemorphologyhavebeenpresentedbefore.InFig1b,however,irregularlyshapedgrainsassembleonaPlaneandgroovesamongtheirregularlyshapedgrainsareeasytodecide(wedefineitascharacteristicB),whichisinagreementwithmanypreviousreports[5-7].InFig.1c,bothcharacteristicA(arrowA)andcharacteristicB(arrowB)wereobserved.IndoingAFMexperiments,weselectedfivedifferentscanareastobeimagedforeachsampleandfoundthatallimagesofeachsamplearerespectivelysimilartoFig.1a,bandc.Also,wenotedthatthesurfaceofinFig.1a.WethinkthatdepositionparameterswillinfluenceAl-Sisurfacemorphology,andthetiltedgrainsmaybesusceptibletomicrocracking.Byreducingthescansizeareato2by2μm(Fig.2aandb).Weobtainedmanyidenticalresultsasdescribedabove,suchasirregularlyshapedgrainsetc.Forthefirsttime,wefoundnanometersizedparticlesonirregularlyshapedgrainsurfacewhichcannotberevealedbySEMbecausethediameterofthesenanoparticlesisabout10nmandtheheightofthesenanoparticlesisintherangeof1.6to2.9nm.Inimaging,wenotedthatrotatingthescandirectionandchangingthescanfrequencydidnotaffectthestructureofthesegrainsasshowninFig.2aandb,rulingoutthepossibilitythatscanninginfluencedtheshapeoftheseparticlesorcausedsomesimilarimagingartifacts.Also,wenotedthatthenanoparticleswerenotobservedontheslopesofthegrooves(Fig.2aandb).Thisphenomenoncanbeexplainedasfollows:thepotentialenergyattheslopeislargerthanthatelsewhere,sotheparticlesseemmorelikelytobedepositedontheseareaswithlowerpotentialenergy.Fig.2c,scansize250by250nm,isazoomtopographicimage(whiteoutlineinb).Itshowsunevendistributionofthenanoparticles.Andtheheightdifferenceofthenanoparticlesindicatesdifferentgrowingspeed.Wethinkbasedonthemorphologyofnanoparticles,thattheheightdifferenceandunevendistributionofthesenanoparticlesshowdifferentgrowingadvantageandindicatethatatomshaveenoughenergytomovetoasuitablegrowingspot.Theenergymaybefromthefollowingsources:surfacetemperaturefluctuation,stressdifferenceorcollisionbetweenhighspeedsputteredatoms.Thesenanoparticlesgoongrowingandformmanyirregularlyshapedgrains.AndtheseirregularlyshapedgrainsfurtherconnecteachotheraccordingtocharacteristicAorB,finallyformingtheAl-Sisurfacemorphology.4.ConclusionWecandrawthefollowingconclusionsfromtheabove.First,theexperimentalresultsshowedthatAFMisapowerfultooltoinvestigatethedetailsofAl-Sisurfacemorphologywhichcangreatlyenrichourknowledgeofthefilmgrowthmechanism.Second,depositionconditionsplayanimportantroleindeterminingtheAl-Sisurfacemorphology.Third,thetwoAl-Sisurfacemorphologycharacteristicsarethatirregularlyshapedgrainsassembleonaplaneandirregularlyshapedgrainstiltinginvaryingdegreespileupinspace.Fourth,forthefirsttime,nanoparticleswereobservedonirregularlyshapedgrainsurfacewhichsuggestedthatthefilmgrowthmechanismwasbyinhomogeneousnucleation.Acknowledgements-BeneficialdiscussionswereheldwithDr.ZhenandMr.Zhu.ThisworkwaspartiallysupportedbytheNationalNaturalScienceFoundationofChina.RFFERENCES｜｜1D.pramanikandA.N.Saxena,SolidStateTechnol.26(1983)127.2D.pramanikandA.N.Saxena,SolidStateTechnol.26(1983)131.3D.pramanikandA.N.Saxena,SolidStateTechnol.33(1990)73.4S.S.IyerandC.Y.Worg,J.Appl.phys.57(1985)4594.5J.F.Smith,SolidStateTechnol.27(1984)135.6D.GerthandD.Katzer,ThinSolidFilm208(1992)67.7R.J.WilsonandB.L.Weiss,ThinSolidFilm207(1991)291.8E.G.Solley,J.H.Linn,R.W.BelcherandM.G.Shlepr,SolidStateTechnol33(1990)409I.SmithandRHowland,SolidStateTechnol.33(1990)53.10L.Peters,SemiconductorInternational16(1993)62.##61D.pramanikandA.N.Saxena,SolidStateTechnol.26(1983)127.2D.pramanikandA.N.Saxena,SolidStateTechnol.26(1983)131.3D.pramanikandA.N.Saxena,SolidStateTechnol.33(1990)73.4S.S.IyerandC.Y.Worg,J.Appl.phys.57(1985)4594.5J.F.Smith,SolidStateTechnol.27(1984)135.6D.GerthandD.Katzer,ThinSolidFilm208(1992)67.7R.J.WilsonandB.L.Weiss,ThinSolidFilm207(1991)291.8E.G.Solley,J.H.Linn,R.W.BelcherandM.G.Shlepr,SolidStateTechnol33(1990)409I.SmithandRHowland,SolidStateTechnol.33(1990)53.10L.Peters,SemiconductorInternational16(1993)62.##A##BATOMIC FORCE MICROSCOPY OBSERVATION OF MAGNETRON SPUTTERED ALUMINUM-SILICON ALLOY FILMS$$$$J.W.Wu,J.H. Fang and Z.H.Lu (National Laboratory of Molecule and Biomolecule Electronics,Southeast University,Nanjing 210096, China Manuscript received 27 October 1995)Abstrcat:Two different surface morphology characteristics of magnetron sputtered aluminumsilicon(Al-Si)alloy films deposited at 0 and 200℃ were observed by atomic force microscopy(AFM).One is irregularly shaped grains put togther on a plane.The other is irregularly shaped grains Piled up in space. Nanometer-sized particles with heights from 1.6 to 2.9 nm were first observed. On the basis of these observations the growth mechanism of magnetron sputtered films is discussed.

关键词: :magnetron sputtering , null , null , null , null