講義成果文件

P-21/C.HighPerformanceSolutionProcessedIZTOTFTattheumProcessTemperatureof230oCAdvancedDisyResearchCen ndDepartmentofInformationDisy,KyungHeeUniversity,Seoul130-701,KoreaWereportahighperformancesolutionprocessedoxidethinfilmtransistor(TFT)producedatthe umtemperatureof230oC.ChloridederivateprecursorswereusedformakingIndiumZTinOxide(IZTO)aschannellayerandAluminumOxide(AlOx)asgateinsulator.TheIZTOTFTexhibitsfield-effectmobilityof6.8cm2/Vs,thresholdvoltageof0.74Vandsubthresholdswingof103mV/dec.TheTFTshowsstableperformanceundernegativebiasandilluminationstress(NBIS).Solutionprocess,OxideTFT,lowtemperature,high-κ,lowpowerconsumption,gatebiasstress,negativebiasilluminationstress.Alongwithtransparentamorphousoxidesemiconductors(TAOS),newprocessesandmaterialshavebeeninvestigated.Amorphousindiumgalliumzoxide(a-IGZO)isastrongcandidate[1]assemiconductingmaterialofoxidethinfilmtransistors(TFT)fordisyapplication.Butothermaterialssuchasindiumzoxide(IZO)[2],ztinoxide(ZTO)derivatives[3]arealsoofreasinginterest.Bothfamiliesdepositedbyvacuumproceshibitafield-effectmobilitymuchhigherthan1cm2/Vsandquitestableperformanceunderpositiveandnegativegatebiasstress.Theremainingissueisthenegativebiasilluminationstress(NBIS)[4],whichaffectsthethresholdvoltage,field-effectmobilityandsubthresholdBesidevacuumprocessing,solutionprocessingofamorphousoxidesemiconductorsstartedwitha-IGZO[5],alongwithIZOandZTO[6,7].Thefirstissueencounteredwastodecreasetheannealingtemperaturebecausethefirsta-IGZOusedforTFTneeded450oC.Variousstrategieshavebeenintroducedtoreducetheannealingtemperaturesuchasdoinoxidesemiconductor[8],modificationofthesolution[9],choiceofgateinsulator[10],designofprecursors[11],andtheuseofnewannealingmethods

modifiedthesolventandaddedindiumtothesolutiontofabricateindiumztinoxide(IZTO).Evenatthelowannealingtemperatureof230oC,theIZTOTFTusingAlOxasthegateinsulatorshowfield-effectmobilityof6.81cm2/V.s,Vth<1V,andsubthresholdswing~100mV/dec.ObtainingsuchahighperformanceTFT,wecharacterizethestabilityoftheTFTundernegativegatebiasstress,andNBIStocheckitsapplicationtoflatpaneldisys.Indiumchloride( l3),t hloride(SnCl2),andzchloride(ZnCl2)wereusedforourprocess.Theyweremixedintoasolventandafewdropsofacidwereaddedtothesolutiontoremoveprecipitate.Thesolutionwasthenstirredandfilteredbeforesp oatingandaluminumchloride(AlCl3)wasalsomixedintoasolventandstirredinaninertTheTFTbacknewasfabricatedusingthefollowingprocess.First,a40nmMolayerwasdepositedbysputteringonglassandthenwaspatternedtoformthegateelectrodes.OnthetopofthisAlOxsolutionwasspoatedandcuredonahotteat~230oC.Thestepwasrepeated5timestoproducea~77nmthickAlOxlayer.Afterviaholeformation,a40nmIZOlayerwassputteredandpatternedtoformsourceanddrainelectrodes.Finally,theIZTOwasspoated,curedinanoven,andthenannealedinafurnaceat200oCfor2hrs.WemeasuredI-VcharacteristicsofTFTsbyusinganAgilent4156Csemiconductorparamenalyzer.Thestresseswereperformedupto2000s.Thenegativebiasstress,andlightstressweretlycarriedouttoseetheimpactofeachstressontheperformanceofTFTs,andthennegativebiasilluminationstress(NBIS)wasalsocarriedout.AnnealingwasdonebeforestressexperimenttohavetheinitialstateofTFTperformance.ForNBISabacklightunitat9000Cd/m2wasused.Thefield-effectmobilityandVthwereachievedinthesaturationregionfromthesquarerootofthedraurrentversusgatevoltagecurve,withCInourpreviousstudies[13,14],wefabricatedan V printedZTOonatransparentbackne(IZOasthemetalcontacts,andsilicondioxideasthegateinsulator),annealedat300oCtoobtainafield-effectmobilityof~1cm2/Vs.Wealsofabricatedandimplementedanewsolutionprocessedaluminumoxide[15]foraZTOTFTandachievedafield-effectmobilityof>30cm2/Vsatthe umannealingtemperatureof300oC.Somesolventcanremainintheoxidesemiconductorwhenthelowtemperatureprocessiscarriedout.Inordertosolvetheissueandtoreduceprocesstemperaturefurther,we

andVthbeingderivedfromthelinearfitwiththe1120?SID2012 ResultsandFigure1.TransfercharacteristicsofaIZTOTFTwithchannelwidthandlengthof100μmand6μm,

P-21/C.Figure3.TypicaltransfercharacteristicsofanIZTOTFTbeforeandafter1hrofwhi ightstresswithoutgatebias.Figure3showstheeffectofwhi ightexposureontheperformanceofTFT.Ascanbeseeninthefigure,thechange Figure2.(left)EvolutionofthetransfercurveofanIZTOTFTundernegativegatebiasstresswithtimeand(right)evolutionofthethresholdvoltagewithtimeThealuminumoxidelayerhastheaverageCoxvalueof80nF/cm2,correspondingtothepermittivityof~7.Figure1showsthetypical(left)transfercharacteristicsand(right)outputofaTFTwithchannelwidthandlengthof100μmand6μm,respectively.Thesaturationmobility,Vth,andsubthresholdswingare6.81cm2/V.s,0.74V,and103mV/dec.,respectively.Theonandoff-currentratiois~107.Figure2(left)showstheeffectofnegativebiasstressatVGS=-3Vonthetransfercharacteristics,whilefigure2(right)showstheevolutionofthethresholdvoltageundernegativebiasaccordingtostretchedexponentialformula

thetransfercharacteristicsuponwhi ightexposureonaIZTOTFTisverysmall;asmallnegativeVthshiftcanbeseen.

t whereV0istheVthvariationatinfinitetime,τisthecharacteristictimeconstant,andβisthestretchedexponentialfactor,andtisthestresstime.Itisfoundthattheevolutionofthethresholdvoltagefollowsastretchedexponentialtimedependencewithτ7.6x104sandβ=0.48.TheTFTafter2000sshowsavoltageshiftof0.3V. Figure4.EvolutionofthetransfercurveofanIZTOTFTwithtimeunderNBISSID2012DIGEST?P-21/C.ConcernedbytheNBISimpactontheTFT,westressaTFTatVGS=-3Vandappliedlightstressatthesametime.TheevolutionofthestressisdepictedonFigure4.TheimpactoftheNBISisnegligibleontheIZTOTFT,althoughadegradationinthesubthresholdregioncanbeidentified.ThebehavioroftheNBISonthesolutionprocessedIZTOTFTwithOxgateinsulatorisdifferentfromtheonereportedforvacuumprocesseda-IGZOonSiO2.TheI-Vcharacteristicsshifttothepositivevalues,andthesubthresholdregionI-Vcharacteristicsisslightlydeteriorated,indicatingdefectstatecreationphenomenanearorattheAlOx/IZTOinterface.WeachievedahighperformancesolutionprocessedIZTOTFTat umprocesstemperatureof230oC.TheIZTOTFTexhibitsfield-effectmobilityof6.8cm2/Vs,thresholdvoltageof0.74Vandsubthresholdswingof103mV/dec.TheTFTshowsstableperformanceundernegativebiasandilluminationstressThisworkwassupportedbytheIndustrialStrategic ,DevelopmentofCoreTechnologyforHighPerformanceAMOLEDon stic]fundedbyMKE/KEIT.K.Nomura,H.Ohta,A.Takagi,T.Kamiya,M.Hirano,andH.Hosono,Nature,432(2004).C.-J.Kim,S.Kim,J.-HLee,J.-S.Park,S.Kim,J.E.Lee,J.Lee,Y.Park,J.H.Kim,S.T.Shin,andU-I.Chung,Appl.Phys.Lett.,95,252103(2009).H.Q.Chiang,J.F.Wager,R.L.Hoffman,J.Jeong,D.A.Keszler,Appl.Phys.Lett.,86,013503

J.-H.Shin,J.-S.Lee,C.-S.Hwang,S.-H.K.Park,W.-Cheong,M.Ryu,C.-W.Byun,J.-I.Lee,andH.Y.Chu,ETRIJ.,31,pp.62(2009).G.H.Kim,H.S.Shin,K.H.Kim,W.J.Park,Y.Choi,B.D.Ahn,andH.J.Kim,SIDInt.Symp.DigestTech.Papers,1258(2008).S.-J.Seo,C.G.Choi,Y.H.HwangandB.-S.Bae,J.Phys.D:Appl.Phys.42,035106(2009).D.-H.Lee,Y.-J.Chang,G.S.Herman,andC.-Chang,Adv.Mater.,19,843S.Jeong,Y.-G.Ha,J.Moon,A.Facchetti,andT.J.Marks,Adv.Mater.,22,1346(2010).H.S.Kim,P.D.Byrne,A.Facchetti,andT.J.Mark,J.AM.Chem.Soc.,130,12580(2008).B.N.Pal,B.M.Dhar,K.C.SeeandH.E.Katz,Nat.Mater.,8,898(2009).K.K.Banger,Y.Yamashita,K.Mori,R.L.Peterson,T.Leedam,J.Rickard,andH.Sirringhaus,NatureMaterials,10,pp.45(2011). M.-G.KimM.G.Kanatzidis,A.Facchetti,T.J.Marks,NatureMaterials,10,pp.382(2011).C.AvisandJinJang,J.Mater.Chem.,21,pp.C.AvisandJinJang,Jpn.J.Appl.Phys.50,01BG03C.AvisandJinJang,Electrochem.Solid-Staett.,pp.J91122?SID2012230oCIZTOTFTChristopheAvis、YounGooKimJinJang130-701，韓國我們報告了一種高性能解決方案加工后的氧化物薄膜晶體管（TFT）230oC體用于制造作為溝道層的氧化銦鋅錫（IZTO）和作為柵極絕緣體的氧化鋁（AlOx）IZTOTFT6.8cm2/Vs0.74V103mV/decTFToTAOS)[1](IZO[2ZTO)31cm2/Vs正負柵極偏壓應(yīng)力下具有相當穩(wěn)定的性能。剩下的問題是負偏壓照明應(yīng)力(NBIS)[4a-IGZO[5]、IZOZTO[6,7]。遇到的第一個問題是降低退火溫度，因為第一個用于TFT的a-IGZO需要450oC。人們已經(jīng)引入了各13,14ZTO（IZO二氧化硅作為柵極絕緣體）300oC1cm2/VsZTOTFT制造并實施了一種新的解決方案處理的氧化鋁[15]，并在300oC的最高退火溫度下實現(xiàn)了>30cm2/Vs的場效應(yīng)遷移率。度，我們修改了溶劑并向溶液中添加了銦來制造氧化銦鋅錫（IZTO）230oC的低退火溫度NBIS實驗我們的工藝用了氯化銦l3)氯化錫(Sl2)和氯化鋅ZnCl2)。將它們混合到溶劑中，并向溶液中添加幾滴酸以除去沉淀。然后將溶液攪拌并過濾，然后旋涂，并將氯化鋁(All3)也混合到溶劑中并在惰性環(huán)境中攪拌。柵電極。在該AlOx溶液的頂部旋涂并在約230oC的熱板上固化。重復(fù)該步驟5次以產(chǎn)生約77nm厚的AlOx40nmIZO200℃2Agilent4156C參數(shù)分析儀測量了TFT的I-V特性。應(yīng)力執(zhí)行長達2000秒。分別進行負偏壓應(yīng)力和光應(yīng)力，以了解每種應(yīng)力對TFT性能的影響，然NBISTFTNBIS，9000Cd/m2Vth在飽和區(qū)中通過C.satWIDS獲得的。(VGS.Vth)2(1)2L和Vth是通過與橫坐標的線性擬合得出的。3.結(jié)果和討論圖3.IZTOTFT在無柵極偏壓的白光應(yīng)力下1小時之前和之后的典型傳輸特性。圖1.IZTOTFT的傳輸特性與圖3顯示了白光曝光對分別為100μm和6μm的溝道寬度和長度的影響。TFT2中的變化。（左）負柵極偏壓應(yīng)力下IZTOTFT隨時間的演變以及（右）閾值電壓隨時間的演變氧化鋁層具有平均Cox值為80nF/cm2，對應(yīng)的介電常數(shù)約為7。圖1顯示了溝道寬度和長度分別為100μm和6μm的TFT的典型（左）特性和（右）輸出。飽和遷移率、Vth6.81cm2/V.s、0.74V103mV/dec。通斷電流比約為107。2（左）VGS3V2（右）則顯示了負偏置應(yīng)VthV01。經(jīng)驗..t。...(2)現(xiàn)，閾值電壓的演變遵循延長的指數(shù)時間依賴性，其中τ=4.NBISIZTOTFTNBISTFTTFTVGS3V4，但NBISIZTOTFTAlOxIZTOTFT