半導體制造技術(shù)：離子注入

Chapter6

IonImplantation

離子注入6.1Introduction–History

簡介—歷史Usedforatomicandnuclearresearch用于原子和核研究Earlyideaintroducedin1950’s20世紀50年代提出的早期概念I(lǐng)ntroducedtosemiconductormanufacturinginmid-1970s.在20世紀70年代中期被引入半導體制造領(lǐng)域6.2StoppingMechanism

阻止機制Ionspenetrateintosubstrate離子注入基體Collidewithlatticeatoms與晶格原子碰撞Graduallylosetheirenergyandstop逐漸失去能量，最終停止Twostopmechanisms兩個阻止機制TwoStoppingMechanism

兩種阻止機制Nuclearstopping（核阻止）Collisionwithnucleiofthelatticeatoms與晶格原子的原子核碰撞Scatteredsignificantly大角度散射Causescrystalstructuredamage.造成晶格損傷electronicstopping（電子阻止）Collisionwithelectronsofthelatticeatoms與晶格原子的自由電子與束縛電子碰撞Incidentionpathisalmostunchanged注入離子的路徑基本不變Energytransferisverysmall能量損失很小Crystalstructuredamageisnegligible晶體結(jié)構(gòu)的損傷可以忽略StoppingMechanism

阻止機制Thetotalstoppingpower（總阻止本領(lǐng)）Stotal=Sn+SeSn:nuclearstopping（核阻止本領(lǐng)）Se:electronicstopping（電子阻止本領(lǐng)）LowE,highAionimplantation:mainlynuclearstopping低能離子注入，主要是核阻止HighE,lowAionimplantation,electronicstoppingmechanismismoreimportant高能離子注入，電子阻止機制更重要StoppingMechanisms

阻止機制RandomCollisions(S=Sn+Se)自由碰撞Channeling(S

Se)溝道BackScattering(S

Sn)背散射IonStoppingPowerandIonVelocity

阻止本領(lǐng)與離子速度NuclearStopping核阻止ElectronicStopping電子阻止IIIIIIIonVelocity離子速度StoppingPower阻止本領(lǐng)IonTrajectoryandProjectedRange

離子軌跡與射程ProjectedRange射程IonTrajectory離子軌跡Collision碰撞IonBeam離子束Vacuum真空Substrate基體DistancetotheSurface到表面的距離IonProjectionRange

注入離子分布ln(Concentration)ln（濃度）ProjectedRange投影射程，射程的平均值SubstrateSurface基體表面DepthfromtheSurface到表面的深度0.0100.1001.000101001000ImplantationEnergy注入能量(keV)ProjectedRange射程

(mm微米)BPAsSbProjectedRangeinSilicon

硅靶中的射程0.000.200.400.600.801.001.20SiSiO2Si3N4AlMaskThickness掩膜厚度(micron微米)SbAsPBBarrierThicknesstoBlock

200keVIonBeam

阻擋200keV的離子束的阻擋層厚度PRImplantationProcesses:Channeling注入過程：溝道Veryfewcollisions很少碰撞Lotsofcollisions大量碰撞Iftheincidentangleisright,ioncantravellongdistancewithoutcollisionwithlatticeatoms如果入射角度合適，離子能夠在不和晶格原子碰撞的情況下運動很遠距離Itcausesuncontrollabledopantprofile會引起不可控的雜質(zhì)分布ChannelingEffect

溝道效應ChannelingIon溝道離子CollisionalIon碰撞離子LatticeAtoms晶體原子qWaferSurface晶片表面Post-collisionChanneling碰撞后溝道效應Collisional碰撞qWaferSurface晶片表面Collisional碰撞

Channeling溝道Post-collisionChanneling

碰撞后溝道效應Collisional碰撞引起

Collisional碰撞引起

Channeling溝道引起DopantConcentration摻雜濃度Distancefromsurface到表面的距離ImplantationProcesses:Channeling注入過程：溝道Waystoavoidchannelingeffect避免溝道效應的方法Tiltwafer,7°ismostcommonlyused（傾斜晶片，7°是最常用的）Screenoxide（屏蔽氧化層）Pre-amorphousimplantation,Germanium（注入前預先無定型處理：鍺）Shadowingeffect陰影效應Ionblockedbystructures（離子受到掩膜結(jié)構(gòu)阻擋）Rotatewaferandpost-implantationdiffusion旋轉(zhuǎn)晶片與注入后的擴散ShadowingEffect陰影效應Polysilicon多晶硅Substrate基體DopedRegion摻雜區(qū)ShadowedRegion陰影區(qū)IonBeam離子束ShadowingEffect

陰影效應Polysilicon多晶硅Substrate基體DopedRegion摻雜區(qū)AfterAnnealingandDiffusion退火和擴散后Q&AWhydon’tpeopleusechannelingeffecttocreatedeepjunctionwithouthighionenergy?為什么不利用溝道效應在離子能量不高的情況產(chǎn)生深結(jié)？Ionbeamisnotperfectlyparallel.Manyionswillstarttohavealotofnuclearcollisionswithlatticeatomsaftertheypenetratingintothesubstrate.Someionscanchanneldeepintothesubstrate,whilemanyothersarestoppedasthenormalGaussiandistribution.

離子束不是完全平行的。許多離子在注入基體后會開始與晶格原子核發(fā)生大量碰撞。只有少數(shù)一些離子會通過溝道滲入基體很深，大量的離子被阻止，就如同正常的高斯分布。DamageProcess

損傷過程Implantedionstransferenergytolatticeatoms注入離子將能量轉(zhuǎn)移到晶格原子

Atomstobreakfree產(chǎn)生自由原子Freedatomscollidewithotherlatticeatoms自由原子與其他晶格原子碰撞Freemorelatticeatoms

使更多的晶格原子成為自由原子Damagecontinuesuntilallfreedatomsstop知道所有自由原子均停止下來，損傷才停止Oneenergeticioncancausethousandsofdisplacementsoflatticeatoms一個高能離子可以引起數(shù)千個晶格原子位移LatticeDamageWithOneIon

一個離子引起的晶格損傷HeavyIon重離子SingleCrystalSilicon單晶硅

DamagedRegion損傷區(qū)LightIon輕離子ImplantationProcesses:Damage注入過程：損傷Ioncollideswithlatticeatomsandknockthemoutoflatticegrid離子與晶格原子碰撞，使其脫離晶格格點Implantareaonsubstratebecomesamorphousstructure基體上的注入?yún)^(qū)域變成無定型的結(jié)構(gòu)BeforeImplantation注入前AfterImplantation注入后ImplantationProcesses:Anneal注入過程：退火Dopantatommustinsinglecrystalstructureandbondwithfoursiliconatomstobeactivatedasdonor(N-type)oracceptor(P-type)雜質(zhì)原子必須處于單晶結(jié)構(gòu)中并與四個Si原子形成共價鍵才能被激活成施主（N型）或受主（P型）Thermalenergyfromhightemperaturehelpsamorphousatomstorecoversinglecrystalstructure.高溫熱能幫助無定型原子恢復單晶結(jié)構(gòu)ThermalAnnealing退火DopantAtom雜質(zhì)原子LatticeAtoms晶格原子ThermalAnnealingDopantAtomLatticeAtomsThermalAnnealingDopantAtomLatticeAtomsThermalAnnealingDopantAtomLatticeAtomsThermalAnnealingDopantAtomLatticeAtomsThermalAnnealingDopantAtomLatticeAtomsThermalAnnealingDopantAtomLatticeAtomsThermalAnnealingDopantAtomsLatticeAtomsImplantationProcesses:Annealing注入過程：退火B(yǎng)eforeAnnealing退火前AfterAnnealing退火后RapidThermalAnnealing(RTA)快速熱退火Athightemperature,annealingoutpacediffusion高溫下，退火超越擴散Rapidthermalprocess(RTP)iswidelyusedforpost-implantationanneal快速熱處理工藝被廣泛應用于離子注入后的退火RTAisfast(lessthanaminute),betterWTWuniformity,betterthermalbudgetcontrol,andminimizedthedopantdiffusion快速退火很快（小于一分鐘），更好的片間均勻性，更好的熱能合理控制和最小化雜質(zhì)擴散RTPandFurnaceAnnealing

快速熱處理工藝與爐退火PolySi多晶硅SiRTPAnnealing快速熱處理工藝退火FurnaceAnnealing爐退火PolySi多晶硅SiGateSiO2Source/Drain源/漏Gate柵QuestionandAnswerWhycan’tthefurnacetemperatureberamped-upandcooled-downasquicklyasRTPsystem?高溫爐的溫度為什么不能像RTP系統(tǒng)那樣快速升溫和降溫？Afurnacehasverylargethermalcapacity,itneedsveryhighheatingpowertoramp-uptemperaturerapidly.Itisverydifficulttorampuptemperatureveryfastwithoutlargetemperatureoscillationduetothetemperatureovershootandundershoot.

高溫爐有很大的熱容積，需要很高的加熱功率去獲得快速升溫。很難避免快速升溫時大的溫度振蕩（溫度過沖和下沖）。IonImplantation:Hardware離子注入：硬件Gassystem（氣體系統(tǒng)）Electricalsystem（電氣系統(tǒng)）Vacuumsystem（真空系統(tǒng)）Ionbeamline（離子束線）ImplantationProcess

注入工藝GasesandVapors（氣體和蒸汽）:P,B,BF3,PH3,andAsH3SelectIon（選擇離子）:B,P,AsSelectIonEnergy（選擇能量）SelectBeamCurrent（選擇束電流）NextStep下一步Implanter離子注入機IonImplanter

離子注入機GasCabin（氣艙）IonSource（離子源）VacuumPump（真空泵）VacuumPump（真空泵）ElectricalSystem（電氣系統(tǒng)）ElectricalSystem（電氣系統(tǒng)）AnalyzerMagnet（磁分析器）BeamLine（束流線）EndAnalyzer（靶室）Wafers（晶片）PlasmaFloodingSystem（等離子注入系統(tǒng)）IonImplantation:GasSystem離子注入：氣體系統(tǒng)Specialgasdeliversystemtohandlehazardousgases特殊氣體傳輸系統(tǒng)處理有害氣體Specialtrainingneededtochangegasesbottles特殊訓練需要改變氣瓶Argonisusedforpurgeandbeamcalibration氬氣被用作清掃和束校準IonImplantation:ElectricalSystem離子注入：電氣系統(tǒng)Highvoltagesystem（高壓系統(tǒng)）Determineionenergythatcontrolsjunctiondepth確定控制結(jié)深的離子能量RFsystem（射頻系統(tǒng)）SomeionsourcesuseRFtogenerateions一些離子源使用射頻來生成離子42IonImplantation:VacuumSystem離子注入：真空系統(tǒng)Needhighvacuumtoaccelerateionsandreducecollision需要高真空來加速離子并且減少碰撞MFP>>beamlinelength平均自由程>>離子束線長度10-5to10-7Torr（10-5

到10-7

托）TurbopumpandCryopump渦輪泵和低溫泵Exhaustsystem（排氣）IonImplantation:ControlSystem離子注入：控制系統(tǒng)Ionenergy,beamcurrent,andionspecies.離子能量，流強和離子種類Mechanicalpartsforloadingandunloading裝卸的機械零件Wafermovementtogetuniformbeamscan晶片移動得到均勻的光束掃描CPUboardcontrolboardsCPU控制板Controlboardscollectdatafromthesystems,sendittoCPUboardtoprocess,控制板從系統(tǒng)中收集數(shù)據(jù)，發(fā)送到CPU板加工CPUsendsinstructionsbacktothesystemsthroughthecontrolboard.

CPU通過控制板返回指令到系統(tǒng)IonImplantation:Beamline離子注入：束流線Ionsource（離子源）Extractionelectrode（引出電極）Analyzermagnet（分析器磁鐵）Postacceleration（偏轉(zhuǎn)后加速）Plasmafloodingsystem（等離子淹沒系統(tǒng)）Endanalyzer（最終分析儀）IonBeamLine離子束線IonSource離子源VacuumPump真空泵VacuumPump真空泵AnalyzerMagnet磁分析器BeamLine束流線EndAnalyzer靶室Wafers晶片PlasmaFloodingSystem等離子注入系統(tǒng)PostAccelerationElectrode后加速電極ExtractionElectrode引出電極SuppressionElectrode抑制電極Hottungstenfilamentemitsthermalelectron熱鎢絲發(fā)射出熱電子Electronscollidewithsourcegasmoleculestodissociateandionize電子與源氣體分子碰撞，發(fā)生分解和電離Ionsareextractedoutofsourcechamberandacceleratedtothebeamline離子從源室中被提取出來，加速成離子束流RFandmicrowavepowercanalsobeusedtoionizesourcegas射頻和微波也可以被用于電離源氣體Ionimplanter:IonSource離子注入機：離子源IonSource

離子源ArcPower（電弧功率）~120VFilamentPower（電源）,0-5V,upto200A+-Anti-cathode對陰極TungstenFilament鎢絲SourceMagnet源磁鐵SourceGasorVapor源氣體或蒸氣Plasma等離子體MagneticFieldLine磁場線RFIonSource

射頻離子源RF射頻RFCoils射頻線圈Plasma等離子體DopantGas雜質(zhì)氣體-+ExtractionElectrode引出電極IonBeam離子束MicrowaveIonSource

微波離子源MagneticFieldLine磁場線Microwave微波MagneticCoils磁線圈ECRPlasmaECR等離子體ExtractionElectrode引出電極IonImplantation:Extraction離子注入：引出Extractionelectrodeacceleratesionsupto50keV引出電極將離子加速至50keVHighenergyisrequiredforanalyzermagnettoselectrightionspecies.磁分析儀需要高能量來選擇合適的離子種類ExtractionAssembly

提取組件IonBeam離子束IonSource離子源Plasma等離子體ExtractionPower引出電壓,upto60kVSuppressionPower抑制電壓,upto10kV++–SuppressionElectrode抑制電極ExtractionElectrode引出電極SlitExtractingIonBeam狹縫提取離子束TopView俯視圖TerminalChassis終端機箱–IonImplantation:AnalyzerMagnet離子注入：磁分析儀GyroradiusofchargeparticleinmagneticfieldrelatewithB-fieldandmass/chargeratio帶電粒子在磁場中的旋轉(zhuǎn)半徑與B場和荷質(zhì)比相關(guān)UsedforisotopeseparationtogetenrichedU235用于分離同位素，得到濃縮U235Onlyionswithrightmass/chargeratiocangothroughtheslit只有具有適當荷質(zhì)比的離子可以通過狹縫Purifiedtheimplantingionbeam注入離子束的純化Analyzer

分析儀IonBeam離子束Smallerm/qRatio小荷質(zhì)比Largerm/qRatio大荷質(zhì)比Rightm/qRatio適當荷質(zhì)比MagneticField(PointOutward)磁場（向外）FlightTube飛行管IonsinBF3Plasma

BF3等離子體中的離子Ions Atomicormoleculeweight離子原子或分子量10B 1011B 1110BF 2911BF 30F2 3810BF2 4811BF2 49

QuestionandAnswerOnly20%ofboronatomsare10B只有20%的硼原子是10B10B+ionconcentrationisonly1/4of11B+

10B+的離子濃度只有11B+的1/410B+beamcurrentis1/4of11B+beamcurrent

10B+的束流強度是11B+的1/4Quadrupleimplantationtime,lowerthroughput四倍的注入時間，低流率10B+islighterandcanpenetratedeeperthan11B+,whydon’tuse10B+indeepjunctionimplantation?10B+比11B+更輕而且滲入更深，為什么在深結(jié)注入中不使用10B+

？IonImplantation:PostAcceleration離子注入：后加速Increasing(sometimesdecreasing)ionenergyforiontoreachtherequiredjunctiondepthdeterminedbythedevice通過該裝置增加（有時減少）離子的能量，使其能夠達到要求的結(jié)深ElectrodeswithhighDCvoltage高直流電壓的電極Adjustableverticalvanescontrolbeamcurrent可調(diào)的垂直葉片控制流強IonImplantation:PlasmaFloodingSystem離子注入：等離子注入系統(tǒng)Ionscausewafercharging離子引起晶片表面充電Waferchargingcancausenon-uniformdopingandarcingdefects晶片表面充電引起非均勻摻雜和弧形缺陷Electionsare“flooding”intoionbeamandneutralizedthechargeonthewafer電子注入離子束中，中和晶片表面電荷Argonplasmageneratedbythermalelectronsemitfromhottungstenfilament熱鎢絲發(fā)射的熱電子產(chǎn)生Ar等離子體PostAcceleration

后加速IonBeam離子束PostAccel.Power后加速電壓,upto60kVSuppressionPower抑制電壓,upto10kV++–SuppressionElectrode抑制電極AccelerationElectrode加速電極TerminalChassis終端機箱–IonBeamCurrentControl

離子束流強控制FixedDefiningAperture固定的規(guī)定孔徑AdjustableVerticalVanes可調(diào)的垂直葉片IonBeam離子束BendingIonTrajectory

彎曲的離子軌跡NeutralAtomTrajectory中性原子軌跡IonTrajectory離子軌跡Wafer晶片BiasElectrode偏轉(zhuǎn)電極ChargeNeutralizationSystem

電荷中和系統(tǒng)（晶片表面充電）Implantedionschargewaferpositively注入離子使晶片表面帶正電Causewaferchargingeffect造成晶片充電效應Expelpositiveion,causebeamblowupandresultnon-uniformdopantdistribution排斥正離子，引起離子束彎曲，造成不均勻雜志分布Dischargearcingcreatedefectsonwafer電弧放電引起晶片表面損傷Breakdowngateoxide,lowyield使柵氧化層擊穿，降低工藝成品率Needeliminateorminimizechargingeffect需要消除或減弱充電效應ChargingEffect

充電效應++++Ionstrajectory離子軌道Wafer晶片ChargeNeutralizationSystem

電荷中和系統(tǒng)

Needtoprovideelectronstoneutralizeions需要提供電子中和正離子

Plasmafloodingsystem等離子體注入系統(tǒng)Electrongun電子槍Electronshowerareusedto電子噴頭PlasmaFloodingSystem

等離子體注入系統(tǒng)DCPower直流電源FilamentCurrent燈絲電流+

TungstenFilament鎢絲Plasma等離子體ArIonBeam離子束Wafer晶片Electrons電子ElectronGun

電子槍IonBeam離子束ElectronGun電子槍SecondaryElectrons二次電子ThermalFilament熱燈絲Electrons電子Wafer晶片SecondaryElectronTarget二次電子靶IonImplantation:TheProcess離子注入：過程CMOSapplicationsCMOS應用CMOSionimplantationrequirementsCMOS離子注入的要求Implantationprocessevaluations注入過程的評價

CMOSImplantationRequirements

CMOS注入的要求ImplantStep注入步驟0.35mm,64Mb0.25mm,256Mb0.18mm,1GbN-wellN型

Well阱P/600/21013P/400/21013P/300/11013Anti-punchthrough反碰穿P/100/51013As/100/51012As/50/21012Threshold閾值B/10/71012B/5/31012B/2/41012Polydope多晶硅摻雜P/30/21015B/20/21015B/20/31015Polydiffusionblock多晶硅擴散阻礙--N2/20/31015Lightlydopeddrain(LDD)輕摻雜漏極B/7/51013B/5/11014B/2/81013Halo(45implant)光圈（45°注入）--As/30/51013Source/draincontact源/漏極接觸B/10/21015B/7/21015B/6/21015P-well

WellB/225/31013B/200/11013B/175/11013Anti-punchthroughB/30/21013B/50/51012B/45/51012ThresholdB/10/71012B/5/31012B/2/41012PolydopeP/30/51015P/20/21015As/40/31015Polydiffusionblock--N2/20/31015Lightlydopeddrain(LDD)P/20/51013P/12/51013P/5/31013Halo(45implant)B/30/31012B/20/31012B/7/21013Source/draincontactAs/30/31015As/20/31015As/15/31015ImplantationProcess:WellImplantation注入過程：阱注入Highenergy高能(toMeV)lowcurrent低流強(1013/cm2)P-EpiP-WaferPhotoresistN-WellP+PhotoresistB+P-EpiP-WaferN-WellP-WellSTIUSGImplantationProcess:VTAdjustImplantationLowEnergy低能

LowCurrent低流強PhotoresistP+P-EpiP-W