光電半導(dǎo)體材料科學(xué)與技術(shù)課件

電子束通過(guò)5-10kV的電場(chǎng)加速后，聚焦并打到待蒸發(fā)材料表面，電子束將能量傳遞給待蒸發(fā)材料使其熔化，電子束迅速損失能量。電子束蒸發(fā)系統(tǒng)的核心部件：電子束槍（熱陰極和等離子體電子）電子束聚焦方式：靜電聚焦和磁偏轉(zhuǎn)聚焦電子束產(chǎn)生后，需要對(duì)其進(jìn)行聚焦而能夠直接打到被蒸發(fā)材料的表面。電子束通過(guò)5-10kV的電場(chǎng)加速后，聚焦并打到待蒸發(fā)材料表面電子束蒸發(fā)源的優(yōu)點(diǎn)電子束轟擊熱源的束流密度高，能獲得遠(yuǎn)比電阻加熱源更大的能量密度。達(dá)到104～109W/cm2的功率密度，可用于蒸發(fā)高熔點(diǎn)材料，如W、Mo等。被蒸發(fā)材料可置于水冷坩鍋中→避免容器材料蒸發(fā)、及其與蒸發(fā)材料反應(yīng)熱量可直接加到蒸鍍材料的表面→熱效率高、熱傳導(dǎo)和熱輻射損失小電子束蒸發(fā)源的缺點(diǎn)電子槍發(fā)出的一次電子和蒸發(fā)材料發(fā)出的二次電子會(huì)使．蒸發(fā)原子和殘余氣體分子電離→影響膜層質(zhì)量?？蛇x擇電子槍加以解決．電子束蒸鍍裝置結(jié)構(gòu)復(fù)雜、價(jià)格昂貴．．加速電壓高時(shí)，產(chǎn)生輻射傷害電子束蒸發(fā)源的優(yōu)點(diǎn)直流濺射(導(dǎo)電靶材)射頻濺射(絕緣介質(zhì)靶材)反應(yīng)濺射(氧化物、氮化物靶材)磁控濺射系統(tǒng)直流濺射(導(dǎo)電靶材)磁控濺射系統(tǒng)濺射的基本原理:

物質(zhì)的濺射現(xiàn)象濺射：荷能粒子與固體（靶材）表面相互作用過(guò)程中，發(fā)生能量和動(dòng)量的轉(zhuǎn)移，當(dāng)表面原子獲得足夠大的動(dòng)能而脫離固體表面，從而產(chǎn)生表面原子的濺射。濺射參數(shù)

濺射閥值：將靶材原子濺射出來(lái)所需的入射離子最小能量值。與入射離子的種類關(guān)系不大、與靶材有關(guān)。

濺射產(chǎn)額

濺射離子速度和能量濺射的基本原理:5濺射物理過(guò)程5濺射物理過(guò)程6入射離子轟擊靶材時(shí)，平均每個(gè)正離子能從靶材打出的原子數(shù)為濺射產(chǎn)額（γ）。M1、M2:分別為入射離子和靶材原子的質(zhì)量；U0:靶材表面束縛能，eV;E:入射離子的能量，eV

α:無(wú)量綱參數(shù)6入射離子轟擊靶材時(shí)，平均每個(gè)正離子能從靶材打出的原子數(shù)為濺濺射物理機(jī)制Underlowenergeticionbombardment(singleknock-On)LinearcollisioncascadeUnderhighenergeticionbombardment(spike)濺射物理機(jī)制UnderlowenergeticionDCSputteringProcesspressure -compromisebetweenthenumberofArionsandthescatteringofArionswithneutralAratomsSputtervoltage

-maximumyield,typical-2~-5kVSubstratebias -controlionbombardmentcharacteristicsSubstratetemperature -modifydepositedfilmproperties

DCSputteringProcesspressureRFSputteringForinsulatingmaterialsduetopositivechargebuildsuponthecathode(target)inDCsystems.Alternatingpotentialcanavoidchargebuildup.Whenfrequencieslessthanabout50kHz,electronsandionsinplasmaaremobileWhenfrequenciesaboveabout50kHz,ions(heavy)cannolongerfollowtheswitching -electronscanneutralizepositivechargebuildupRFSputteringForinsulatingmaMagnetronSputteringI.MagnetronConfiguration:planarNdFeBbarmagnetwithamagneticfieldof~0.5GonthetargetfrontsurfaceElectronmotionisconfinedtoaracetrackduetodriftingbyEandBperpendiculartoeachother.MagnetronSputteringI.Magnetr111112化學(xué)氣相沉積ChemicalVaporTransport

GasmeasurementandmonitoringTransportofmoleculesbygasflowanddiffusionTransportofheatbyconvection,conduction,andradiationChemicalreactionsinthegasphaseandatthesurfaces12化學(xué)氣相沉積ChemicalVaporTranspo化學(xué)氣相沉積分類常壓CVD（APCVD）低壓CVD（LPCVD）等離子增強(qiáng)CVD（PECVD）化學(xué)氣相沉積分類常壓CVD（APCVD）低壓CVD等離子增強(qiáng)光電半導(dǎo)體材料科學(xué)與技術(shù)課件CVD薄膜生長(zhǎng)過(guò)程氣體源進(jìn)入反應(yīng)器；源材料擴(kuò)散至表面；源材料吸附在表面；產(chǎn)生化學(xué)反應(yīng)；生成物形成晶核；晶核形成島狀物；形成連續(xù)薄膜；氣體副產(chǎn)物排出CVD薄膜生長(zhǎng)過(guò)程氣體源進(jìn)入反應(yīng)器；源材料擴(kuò)散至表面；源材料fundamentalparametersexperimentalparametersreactantconcentrationpressurediffusivitygasvelocityboundarylayerthicknesstemperaturedistributionreactorgeometrygasproperties(viscosity...)MasstransportdependsonCVD生長(zhǎng)過(guò)程中的質(zhì)量輸運(yùn)兩種傳輸模式：分子流傳輸（氣體擴(kuò)散）粘滯流傳輸(反應(yīng)物傳輸至襯底表面進(jìn)行反應(yīng))fundamentalparametersexperimeCVD薄膜的主要性能參數(shù)膜厚均勻性（進(jìn)行多點(diǎn)膜厚測(cè)量）臺(tái)階覆蓋性：-側(cè)壁覆蓋sidewallstepcoverage-底部覆蓋bottomcoverage-保角性Conformality應(yīng)力-熱應(yīng)力thermalstress-內(nèi)應(yīng)力intrinsicstress(thickness,depositionrate,depositiontemperature,impurities…)

CVD薄膜的主要性能參數(shù)膜厚均勻性（進(jìn)行多點(diǎn)膜厚測(cè)量）臺(tái)階覆光電半導(dǎo)體材料科學(xué)與技術(shù)課件等離子體增強(qiáng)CVD在射頻功率條件下，反應(yīng)氣體從等離子中獲得激活能，被激活并增強(qiáng)化學(xué)反應(yīng)，實(shí)現(xiàn)高效率的化學(xué)氣相沉積等離子轟擊能夠去除表面雜質(zhì)，增加薄膜的附著性反應(yīng)溫度低于其它CVD薄膜沉積方法等離子體增強(qiáng)20等離子體基本物理性質(zhì)等離子中包括相同數(shù)目的離子和電子，呈現(xiàn)電中性。用于刻蝕的等離子體中帶電粒子密度109-1012

個(gè)/cm-3。等離子中電子溫度>104K,刻蝕過(guò)程中與室溫中性氣體分子生成活化自由基，與襯底材料結(jié)合生成揮發(fā)氣體產(chǎn)物，從而刻蝕襯底。20等離子體基本物理性質(zhì)等離子中包括相同數(shù)目的離子和電子，呈Application:

–maskstopreventoxidationforLOCOSprocess –finalpassivationbarrierformoistureandsodiumcontaminationPECVDLPCVD沉積氮化硅Application:沉積氮化硅原子層沉積技術(shù)(AtomicLayerDeposition)ALDisamethodofapplyingthinfilmstovarioussubstrateswithatomicscaleprecision.Similarinchemistrytochemicalvapordeposition(CVD),exceptthattheALDreactionbreakstheCVDreactionintotwohalf-reactions,keepingtheprecursormaterialsseparateduringthereaction.ALDfilmgrowthisself-limitedandbasedonsurfacereactions,whichmakesachievingatomicscaledepositioncontrolpossible.Bykeepingtheprecursorsseparatethroughoutthecoatingprocess,atomiclayerthicknesscontroloffilmgrowncanbeobtainedasfineasatomic/molecularscalepermonolayer.原子層沉積技術(shù)ALDisamethodofappl原子層沉積過(guò)程與設(shè)備Releasessequentialprecursorgaspulsestodepositafilmonelayeratatimeonthesubstrate.Theprecursorgasisintroducedintotheprocesschamberandproducesamonolayerofgasonthewafersurface.Asecondprecursorofgasisthenintroducedintothechamberreactingwiththefirstprecursortoproduceamonolayeroffilmonthewafersurface.3.Twofundamentalmechanisms:ChemisorptionsaturationprocessSequentialsurfacechemicalreactionprocess4.Sinceeachpairofgaspulses(onecycle)producesexactlyonemonolayeroffilm,thethicknessoftheresultingfilmmaybepreciselycontrolledbythenumberofdepositioncycles.原子層沉積過(guò)程與設(shè)備ReleasessequentialExample:ALDcycleforAl2O3depositionStep1Example:ALDcycleforAl2O3dStep2Step2Step3Step3Step4Step4Step5Step5Step6Step6After3cyclesAfter3cyclesEachpairofgaspulses(onecycle)producesexactlyonemonolayeroffilm,thethicknessoftheresultingfilmmaybepreciselycontrolledbythenumberofdepositioncycles.Eachpairofgaspulses(onecMaintypesofALDreactorsClosedsystemchambers(mostcommon)Thereactionchamberwallsaredesignedtoeffectthetransportoftheprecursors.SchematicofaclosedALDsystemRef:"TechnologyBackgrounder:AtomicLayerDeposition,"ICKnowledgeLLC,24April06.</misc_technology/Atomic%20Layer%20Deposition%20Briefing.pdf>.MaintypesofALDreactorsScheProcessTemperature[1]TheVerano5500?A300-mmALDsystembyAvizaTechnology,Inc.[1][1]1"TechnologyBackgrounder:AtomicLayerDeposition,"ICKnowledgeLLC,24April06.</misc_technology/Atomic%20Layer%20Deposition%20Briefing.pdf>OnecycleProcessTemperature[1]TheVerCandidatesforHigh-Kdielectrics

Film

Precursors

Al2O3 Al(CH)3,H2OorO3

HfO2 HfCl4orTEMAH,H2O ZrO2 ZrCl4,H2OALDApplicati