LTPS TFT教育(完整)

LTPS-TFT関連-20164.12-*©2014天马微电子股份有限公司.Allrightsreserved目录DirectoryLTPSTFTShortchaneleffectetc.ＴＦＴstructureandperformancePoly-Sispecificcharacteristics1423TFT特性(前回おさらい复习）gsDrainGatesoucedrain-100102030Gate电圧(V)10-1210-1110-1010-910-810-710-610-510-410-3Draincurrent(A)Id-Vg特性idealistcTFTFig.5Vg=0VVg=-10VN+Vg=+10VP+OnOffOffAnlormalusleakageUsuallyuseofLDDstructuretoReduceleakageNMOSandPMOSgatesoucesoucegateDrainOffOffOnelectronholeＣＭＯＳＮＭＯＳＰＭＯＳBothNMOSandPMOSNMOSonlyPMOSonlyProcessstep2PRstepdecreaseCHDandPDNeedLDD2-3PRstepdecreasePossibilitytoreduceLDDCircuitconfiglationEasy：inventorcircuitDifficult；needbootstrapDifficult；needbootstrapTFTHighperformanceHighperformanceLowperformanceICconventinalcompatibleNeedspecialVoltageVgh-VglMOREthanVgh-VglMOREthanVgh-VglprocessLowtempavailable;TPimproveapplicationHighperformanceComplicatedcircuitintegrationGoodforOLEDapplication、topemissionCompariconCMOS、NMOSandPMOSInverterCircuitVDDVDDCMOSInverterPMOSInverterVSSVSSInputSignalInputSignalVSSVDDVSSVDDVSSVDDVSSVDDVSSVDDOutputWaveformOutputWaveformVtQ4Q1Q2Q3Q4ThresholdvoltageofQ4Rail-to-RailOutputOutputVoltageislimited输出振幅和电源电压相同输出振幅只有阈值电压比电源电压小BootstrapCircuitforPMOSShiftRegisterVDDQ1Q2CgsVg2OUTVSSVg2OUTVDDVSSOutputCircuitwithBootstrapCircuitVg1SWSWONOFF(Hi-Z)ONVDDCLKCLKVSSVDDSetResetVDDVSSVg1CgdOutputcontrollerSet期间:设定Vg1=High,Vg2=LowOutput期间:将SW打开Reset期间:设定Vg1=Low,Vg2=HighDrivingVoltageishigherthan(Vgh-Vgl)TFT構造的差異ゲートソースドレインゲートソースドレインゲートソースドレインゲート絶縁膜ゲート絶縁膜ゲート絶縁膜poly-Sin+（P+）-poly-Sipoly-Sin+（P+）-poly-Sia-Si:Hn+-a-Si:HToppgate構造一般的poly-SiTFT構造Selfalign順suttge構造botomgate構造一般的a-SiTFT構造Fig.14BottomgateInvertedstagardTopgatestaggerdCo-planerapplicationA-Si;HconventionalusePastusea-SI<PSLTPSconventionalSDSDandGateoverlap,largerparasiticCnotgoodforsmallL←SDandGisnotoverlapsmallCgsandgoodforLcontrolInsulatorG=ILDGI=ILDGIandILDindividualDopingUsuallyuseofvaporphase,notgoodforCMOS←sometimeIMPSelfaligndopingwithIMP,GoodforCMOSELACrystallizationissuppressbygateOKOKLSBottomgatecanbelightshieldNeedadditionalLSNeedadditionalLSMISContinuasMISdepositionNeedcontrolofGIinterfaceNeedcontrolofGIinterfaceComparisonofeachTFTstructure単結晶silicon（半導体）Poly-Si（SOG）多結晶a－Si:HAmorphassilicon結晶粒の境界結晶粒Si原子Hydrogenatom400-700cm2/Vs-150cm2/Vs0.1-1.0cm2/Vs各種silicon膜比較移動度Fig.151.00E-141.00E-131.00E-121.00E-111.00E-101.00E-091.00E-081.00E-071.00E-061.00E-051.00E-041.00E-03-10-505101520GateVoltage(V)DrainCurrent(A)LTPS-TFTTr特性差a-Si:H-TFTFig.34Self-aｌignLDDDefinitionofTFTcharacteristics:Ids,gm,µ线性区的电流方程：221dsoxdsVVdsVthVgsCLWI饱和区的电流方程：2)(21thgsoxVVCLWIdsgm=跨导(trans-conductance)是Ids对Vgs的偏微分，表示的是栅极对沟道的控制能力线性区跨导：饱和区跨导：gm＝µCoxVdsWLμ＝µiexp(-)Φ＝~ｅNtµe＝gmL11WCoxVdsµeff＝gmL11WCoxVg-Vthgm＝µCox(Vg-Vth)WLgm=⊿Ids⊿Vgs电场効果移動度実効移動度Vds=Vg-VthIdsgm,µμi=intrinsicmobilityΦ=barriaheigthNt=trapdensityΦｋTElectricpropertyofpoly-SiElectricpropertyofpoly-SiA-Si;Htempincrease→mobilityincreaseBarriemodelSinglecrystalSitempincrease→mobilitydecreaselatticescatteringeffectPolySitempincreasealmostsamecompensatetwoeffectbutleakagecurrentincreaseTemperaturedependenceofSiTemperaturedependence&barrierheightconductionValenceTrapBANDElectronstateElectronpotencial0KRT？100C？ElectroncanbeexistonconductionbandItcanflowmoreactivelywithhightemperatureThedpendenceoftemperaturegaveusbariahight----GrainbundaryIncaseofpolysilicon,resistivityisnotlinearwithdopingconcentrationduetothegrainboundarytraps.TheunlinearregioniscoincidencewithtrapdensityofpolySiThisunlinealityisdependoncrystalineLDDdopingregionissometimesclosetothisregion,sowehavetobecarefullytotunethisdopingconditionTemperaturedependenceofTFTpropertygaveusinportantinformationaboutcrystalquality.Arrheniusplotisusefulmethodtogetsomephysicalparameter-3-2.5-2-1.5-1024681012141618202224262830323436L/umSP_Vth/L-dependenceW=20Vth(Vd=0.1)Vth(Vd=10)0.0E+002.0E-054.0E-056.0E-058.0E-051.0E-041.2E-04024681012141618202224262830323436L/umSP_IonL/W=1Io…TFTstructure–ｐch.Ldependence-Asforthep-chvtdecreaseisobservedlessthan4umofchannellength.Lshouldbeover4umPSATFT_W20_C41.E-141.E-131.E-121.E-111.E-101.E-091.E-081.E-071.E-061.E-051.E-041.E-03-15-10-50510Vg(V)Id(A)L=3L=4L=5L=10TFTstructure–nch.Ldependence-Asforthen-chVthdecrease(Vd=0.1)isobservedinL3.0um(L=M1designvalue)Weshouldnotemploylessthan3.0umforthen-ch.L.00.511.522.5024681012141618202224262830323436L/umSN_Vth/LLDD=1.5/W=20Vth(Vd=0.1)Vth(Vd=10)TFTstructure–LDDdependence-1E-131E-121E-111E-101E-091E-08-10123LDD(um)00.000050.00010.000150.00020.000250.00030.000350.00040.000450.0005-10123IoffLessthan0.5umLDDLeakagecurrentrapidincreaseWithinvestigationofoverlayaccuracy1.5umisapropriate1.E-131.E-121.E-111.E-101.E-091.E-081.E-071.E-061.E-051.E-041.E-031.E-02-10-5051015Draincurrent(A)Gatevoltage(V)Ids(10V)NLL0L0.5L0.75L1L1.25L1.5L1.75L2L2.5designOverlaymarginEND•次回候補•Si/bufferandELAprocess•GIinterfaseandCVDprocesshighdensity•DrainengineeringandIMP/Acｔ•MetalizationandPLNlowKhighK•GlasssubstrateTPcontrol•LCDvsOLEDprocessdesign、TFTspec•Pixeldesighnxtalkflickerおまけ•refLeakagecurrentmechanismforp