1、器件制造身成闈咐MnufacturingmdApplicationofDevicedoi：10.3969/j.issn.1003-353x.2010.01.009CVProfilingofUltrashallowJunctionsUsingaBuriedLayerwithStep-LikeDopingProfileXuCuiqin1,2,PopadicMilo§2,NanverL.K.2,RuGuoping1(1.StaleKeyl/ibofASICandSystems,DepartmentofMicroelectronics,FudanUniversity,Shanghai2004

2、33,China;2.laboratoryofECTM,DIMES,DelftUniversityofTechnology,CHDelft2600.Netherlands)Abstract：Two-sidedC-VtechniquewasinvestigatedforapplicationindopingprofilecharacterizationofSiultrashallowp*-njunctions.Expressionswerederivedfortheevaluationofthedopingprofileinthep*region,basedontheknowledgeofcap

3、acitance-voltage(C-Vr)relationshipofthep*-ndiode,thedopingprofileinnregion,andthedepletionwidthinnregionatthermalequilibrium(xM).SteppeddopingprofileinnregionwasdesignedforaccuratedeterminationofxM,acrucialparameterfortheextractionofthedopingprofileinthep*region.Medicisimulationswerecarriedoutforthe

4、C-VRrelationshipsofthep*-nandn-Schottkyjunctionswiththesamestep-likenprofile.ThedopingprofileinnregioncouldthenbeextractedfromtheC-VRrelationshipoftheSchottkydiode.Theisdeterminedwithanaccuracyof1.8nmbyacriteriondeveloped.Andthedelingprofileinthep*regioncanfinallybeextractedandshowntobeingoodagreeme

5、ntwiththeMedicisimulationresults.Keywords：two-sidedjunction;C-V;ultra-shallowjunctionsCLCnumber：TN301.07;TN3O5.3Documentcode：AArticleID：JOB-353X(2010)01-0039-01EEACC:253OB;255OB;7110用階梯狀摻雜埋層對超淺結進行C，剖面分析徐翠芹PopadicMilo*,NanverL.K.2,茹國平】（1.復旦大學微電子系專用集成電路與系統國家重點實驗室，上海200433；2.代爾夫特工業大學ECTM/DIMES實驗室，荷蘭代爾夫

6、特2600）摘要：研究了應用雙邊C-V法測量超淺結（如p*-n結）的疹雜分布。推導了在已知p-n結的電容-電壓（C-*）關系、n區摻雜、以及熱平衡下n區耗盡層寬度（xM）的情況下計算p區疹雜濃度分布的公式。與湖是計算p區摻雜分布所需的一個關鍵參數，通過將n區摻雜設計成階梯狀，可實現對*的精確提取。用Medici對具有相同的階梯狀摻雜n區的p'-n和n-肖特基結進行器件仿真可得其C-Vn關系。運用常規GU法，由肖特基結的C-Vn關系可提取出n區摻雜濃度。實現了對*3的精確提取，其精度達1.8nma基于精確的為洵，運用雙邊C-V法提取的p*區的摻雜濃度分布與Medici仿真結果非常吻合。關

7、鍵詞：雙邊結；電容-電壓；超淺結中圖分類號：TN3W.07；TN3O5.3文獻標識碼：A文章編號：1003-353X（2010）01-0039-040IntroductionUltrashallowsourceanddrain(S/D)junctionswithFoundationitem：Shanghai-AppliedMaterialsResearchDevelopmentFund(07SA06)highandabruptdopingprofilearenecessaryforgoodperformanceofMOSFETs'E.Itisveryimportantandchalle

8、ngingtomeasuretheactivateddopinglevelanditsdistributionthroughtheultrashallowjunctionsbecauseofthestringentdepthresolutionandquantitativeaccuracyrequirements.Atpresent,thereareseveralprofilingtechniques,suchassecondaryionmassspectrometry(SIMS),spreadingresistanceprofiling(SRP),differentialcapacitanc

9、e-voltage(C-V)profiling,electrochemicalcapacitance-voltage(ECV)profiling,profiling,Halleffectprofiling,andRutherfordbackscattering(RBS.Eachlechniquehasitsadvantagesanddisadvantages.Inthiswork,anoveltwo-sidedC-Vprofilingisdeveloped.ThedopingprofileononesidecanbeextractedbasedontheknowledgeoftheC-Vrel

10、ationship,thedopingprofileontheotherside,andtheboundaryofdepletionregionatthermalequilibrium(.Thetwo-sidedprofilingtechniquecanbesuccessfullyappliedfortheprofilingofp+regionofp*-njunctionwithasteppedndopingprofile.1 TheoryofTwo-SidedCVProfilingTechniqueThedopingprofileofanarbitrarydopedp-njunctionis

11、showninFig.1./Vd(x)andN.(x)representthedonorprofileinnregion(x<0)andacceptorproGleinpregion(x>0),respectively.W(VT)isthewidthofthedepletionregionwhenthetotalpotentialdropthroughthejunctionequalstoVytwhichisthesumofthebuild-involtage,andreversebiasVr.xnandxparethecoordinatesofthedepletionregion

12、edgesinthevicinityofneutralnandpregions,respectively.Fig.1DeGnitionsofanarbitrarydopedpnjunction圖1任意摻雜pn結的定義Assumingthatalldopantatomsareactive,withdepletionapproximation,theequationscanbeobtained一習:electricallyfollowing收(4)%"=一L業與g1-秋(*)宓住QAtthermalequilibrium,equalsto*，andxnequalstoxM.FromEq.

13、(1),thefollowingequationcanbeobtainedWithacertainreversebiasvoltageapplied.Eq.(1) canbewrittenas；住山一滁+'齋(5)CombiningEqs.(4)and(5)yieldsQbi="eJo敗(Vr)=-:CUr)Mr(6)WhereAistheareaofthediode,tisthepermittivityofthesemiconductor,andCisthecapacitanceofthediode.Witharightassumptionofxoandtheknowled

14、geofthedopingprofileinnregion,usingEq.(6),xnti(Ur)whichstandsfortheestimatedrelationshipbetweenxnandVrcanbecalculated.ThenbasedonthemeasuredC-Vrrelationshipofp-njunction,W()canbecalculatedandtheestimatedxp-relationship,xpM(i(Yr)canbecalculatedusingEq.(2).Intheend,N.(xp)canbereconstructedfromEq.(3).2

15、 MediciSimulationofTwo-SideC-VProfilingInthetwo-sidedC-Vprofiling,isanimportantbutunknownparameter.What'smore,thedopingprofileinnregioncannotbetakenasknowndirectly.Inthiswork,itissuggestedthatifusingap*-njunctionwithastep-likenprofile,thevalueofcanbeevaluatedaccurately.Andthedopingprofileinnregi

16、oncanbemeasuredonn-Schottkydiodewiththesamenprofileasp*-njunction.MedicisimulationsareimplementedfortheC-VRrelationshipsofp*-nandSchottkydiodeswiththesamestep-likedopingprofileinnregion.Atthermalequilibrium,thesimulateddopingandcarrierprofilesofp*-njunctionwithstep-likenprofileareshowninFig.2.Theare

17、asofthep*-ndiodeandSchottkydiodearebothsetto1mx1pm.DCsolutionsofSchottkyandp*-ndiodearesolvedatdifferentreversebiases,0-25Vand015Vwithastepof0.1V,respectively.Duringthisprocess,Poisson*sequation,continuityequationsandthecarriertransportequationsareallcoupledandsolvedbyusingnumericalmethod.Mediciperf

18、ormsACanalysisasapost-processingstepaftereachDCsolution.ACsmallsignalsimulationsarecarriedoutateachDCbiasingbyapplyingasinufu)idalsignalutafrequencyof1MHzwithasmallamplitudeof10mV.ThesimulatedC-VKcharacteristicsofthep*-ndiodeandn-SchottkydiodewiththedopingprofilesareshownintheinsetofFig.2.Fig.2Simul

19、atedcarrieranddopantconcentrationprofilesofp*-njunctionatthermalequilibrium,theinsetshowsthesimulatedC-VHcharacteristicsofthep*-nandn-Schottkydiodes圖2仿真中的p-n結摻雜濃度分布以及熱平衡F的城流子濃度分布，插圖為仿真得到的p-n結和n肖特基結的C-*關系Takingtheestimatedelectronprofileofn-Schottkydiodeastheelectronprofileatthermalequilibriumofthep*

20、-ndiode,basedontheMedicisimulatedCVKrelationshipofp*-njunction,two-sidedprofilingtechniqueisimplementedwithdifferentassumptionofasiwinw.=-99-96nm).Withdifferent,Mumc,differentxpzi-VrrelationshipscanbecalculatedassliowninFig.3.Theoretically,thedepletionwidthinpregionshouldincreaseasthereversebiasincr

21、eases.However,-Kt/VFig.3Estimatedxp-VKrelationshipsfordifferentxM,uiwe圖3不同gi下所估算出的x-VH關索asshowninFig.3,withla建eraume,theestimatedxp-VKrelationshipsdecreaseatthefirstfewbiaspoints.Thisabnormalphenomenoncanbeexplainedasfollows.AsindicatedinFig.2,theestimatedelectronconcentrationdecreasesasxincreases.F

22、orthesameamountofelectronstobedepleted,ifx*8umrislargerthantherealvalueof為thestepofxn)willbelargerthantherealvalue.IfaMumcistoolarge,thestepofxnMti(Vr)maybeevenlargerthanthestepofW(Yr),whichinducesxpeslj(FR)todecreaseatthefirstfewbiaspointsuntilxnreachesthehighlydopedregion.Thisphenomenonisillustrat

23、edmoreclearlyinFig.4.With丸sazEeequals-96nm,forthefirstfewbiaspoints,thestepwidthofxn_cMi(Hr)islargerthanthatofW(Vr),sothestepofxp5(*)isnegative,andxpe8ti(Hr)woulddecreaseatthefirstfewbiaspoints.Afterafewbiassteps,theconcentrationdifferenceinducedbythelargerxMassumcwilldisappearandthestepofxpwli(VR)b

24、ecomepositiveandxpc#li(Vr)willincrease'*.ThisphenomenonoffersawaytodeterminetheupperlimitofInthiscase,thelimitisthattheassumedshouldbesmallerthan-97.2nmasindicatedinFig.3.If心.umeissmallerthantherealvalueof«thestepofxncgli(Vr)willbesmallerthantherealvalue,sothestepofxpMli()willalwaysbepositi

25、veandxpeMi(VR)willalwaysincreasewithVr.Thereforeitisdifficulttofigureoutthelowerlimitoffromthexprelationship.Ontheotherhand,thewrongaMMinw.willresultinnotonlywrong%pwlibutalsowrongNaIf*洵皿叩職issmallerthantherealvalueofxp_mi(Ur)seemsFig.4Withxz=-96.0nm,thestepsofdepletionwidth,theestimatedxn,andtheesti

26、matedxpasfunctionsofreversebias圖4七45=-96.0nm時.耗盡層寬度、估算出的%、和與反偏電斥的關系normal,buttheestimatedp+dopingprofile,asshowninFig.5,isnotsmooth'】.ThisphenomenoncanbeusedasacriteriontodeterminethelowerlimitofwhichisspecifiedasxMmin.AsshowninHg.5,whendecreasesto-99nm,theeg|j-xbecomesnon-smooth,Fig.5Estimatedp

27、*dopingprofilewithxMaMluin<.=-98.0,99.0and-100.0nm圖5xs.ze為-98.0,-99.0,-100.0nm時所提取的P區摻雜濃度分布InFig.6istheacceporprofileestimatedwith=-98nm,andthesimulatedacceptorprofileandholeprofileatthermalequilibrium.Fig.5Estimatedp*dopingprofilewithxMaMluin<.=-98.0,99.0and-100.0nm圖5xs.ze為-98.0,-99.0,-100.0n

28、m時所提取的P區摻雜濃度分布InFig.6istheacceporprofileestimatedwith=-98nm,andthesimulatedacceptorprofileandholeprofileatthermalequilibrium.rm。/*,NAlthoughitisimpossibletohavetheexactvalueofrealinpractice,Netli(x)shouldbeveryclosetothetruevalueswhentheinterval(xMmin,)issmallenough,around1.8nminthiscase.Astheexperi

29、mentalapplicationofthetwo-sidedC-VproGlingtechniqueisconcerned,accuratemeasurementofjunctionareaisnecessary.Otherwise,thedopingprofileinnregionandconsequentlythedopingprofileinthep*regioncannotbesuccessfullyestimated.Fig.6Acceptorprofileestimatedwithx”=-98.0nm,aridthesimulatedacceptorprofileandholep

30、rofileatthermalequilibrium圖6xo=-98.0nm時所提取的受主摟雜濃度分布，及仿真所得到的熱平衡下的受主和空穴濃度分布Fig.6Acceptorprofileestimatedwithx”=-98.0nm,aridthesimulatedacceptorprofileandholeprofileatthermalequilibrium圖6xo=-98.0nm時所提取的受主摟雜濃度分布，及仿真所得到的熱平衡下的受主和空穴濃度分布?£>MWConclusionThenoveltwo-sidedC-VproGlingtechniqueisproposedt

31、hatthedopingprofileononesideofp-ndiodecanbecalculatedbasedontheknowledgeoftheC-*relationship,thedopingprofileontheotherside,andtheboundaryofdepletionregionatthermalequilibrium.Hietwo-sidedC-VprofilingtechniqueissuccessfullyappliedforSiultrashallowjunctions.Theteststructureofp*-nandn-Schottkydiodeswi

32、ththesamestep-likenprofileisdesignedforextractionofthedopingprofileinthep*regionusingthetwo-sidedprofilingtechnique.BasedontheMedicisimulationoftheC-relationshipsofultra-shallowp*-nandn-Schottky,ononehand,thedopingprofileonthensidecanbeextractedfromtheC-VRrelationshipofSchottkydiode.Ontheotherhand,w

33、ithdifferentaume»applyingthetwo-sidedC-Vprofilingtechnique,theupperandlowerlimitsofcanbedetermined,baseonthe氣。"*andVRrelationships,respectively.Theaccuracyofisshowntobeabout1.8nm.Itisdemonstratedthatifisassumedtobewithintheupperandlowerlimits,thedopingprofilesinthep*regioncanbeaccuratelyev

34、aluated.Thereforeitcanbeconcludedthatthenoveltwo-sidedC-Vprofilingtechniquemaybeappliedfortheextractionofthedopingprofileofultra-shallowjunctions.(下轉第89頁)了大量的鍵合過程中換能桿末端軸向的速度信號。通過分析這些鍵合的強度得到了欠鍵合和過鍵合對應的功率設置范圍。分析了超聲功率設置和鍵合溫度對換能桿振幅的影響規律，解釋了不同功率設置和溫度導致欠鍵合和過鍵合的可能原因，建立了功率設置和溫度對換能桿振幅影響的模型。參考文獻：】WANGFL,UJH,H

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