半導(dǎo)體材料66-77課件

Semiconductormaterials

Lecturer:AiminLiu&WeifengLiu劉愛(ài)民劉維峰

1半導(dǎo)體材料及器件工藝技術(shù)（四）1噴霧熱解成膜技術(shù)2CVD成膜技術(shù)低壓CVD、常壓CVD、離子增強(qiáng)型CVD、MOCVD3擴(kuò)散及陽(yáng)極氧化技術(shù)2超聲噴霧熱分解裝置示意圖

35（a）UndopedZnOfilmsurfaceandcrosssection100nm100nm(b)N-IncodopedZnOfilmsurfaceandcrosssection100nm100nm6CVD薄膜生長(zhǎng)7CVDSYSTEM91011CVD爐管內(nèi)的氣流13CVD化學(xué)反應(yīng)Disproportionation

irreversibleAsCl3(g)＋3Ga(s)3GaCl(g)＋1/4As4(g)3GaCl(g)＋1/2As4(g)2GaAs(s)＋GaCl3(g)Disadvantages: multizonefurnace lowgasflow lowreactionefficiency(<66%) systemcontamination(hotwall)14CVD化學(xué)反應(yīng)Pyrolysis

irreversibleHydridereaction,SiH4(g)Si(s)＋2H2(g)Metal-organicreaction

MOCVD(CH3)3Ga(g)＋AsH3(g)GaAs(s)＋3CH4(g)Advantages: lowgrowthtemperature coldwallreactorDisadvantage: chemicalpurityandcost15氣體的擴(kuò)散及表面反應(yīng)171819Plasma-EnhancedCVD21以不同法成長(zhǎng)Si3N4之比較22PECVD、LPCVD、APCVD

之比較232526TheMOVDgrowthsystem27Reactor-129AixtronModel-2400reactor30VaporpressureofmostcommonMOcompoundsCompoundPat298K(torr)ABMeltpoint(oC)(Al(CH3)3)2TMAl14.2278010.4815Al(C2H5)3

TEAl0.041362510.78-52.5Ga(CH3)3

TMGa23818258.50-15.8Ga(C2H5)3

TEGa4.7925309.19-82.5In(CH3)3

TMIn1.7528309.7488In(C2H5)3

TEIn0.3128158.94-32Zn(C2H5)2

DEZn8.5321908.28-28Mg(C5H5)2

Cp2Mg0.05355610.56175Log[p(torr)]=B-A/T

31HorizontalMOVPEReactor32MOVPEReactor

3334

擴(kuò)散系統(tǒng)示意框圖1.氫氣入口；2.氫氣出口；3.石墨舟；4.加入爐管；5.抽氣口；6.分子泵；7.機(jī)械泵。

擴(kuò)散系統(tǒng)示意框圖35石墨擴(kuò)散舟結(jié)構(gòu)圖Structureofgraphitecrucible3637SchematicdiagramofAnodicOxidationequipment

GaSb做陽(yáng)極，鉑片做陰極，電解液是酒石酸與乙烯乙二醇混合后的一種水溶液

陽(yáng)極氧化38陽(yáng)極氧化膜的形成機(jī)理:電極反應(yīng)：金屬（M）的陽(yáng)極氧化，首先是電解水。在電解液中，通電后在電流作用下發(fā)生水解，同時(shí)在陰極放出氫氣。H2O→H++OH-陰極6H+6e→3H2↑陽(yáng)極6OH--6e→3H2O3[O]2M3[O]→M2O3陽(yáng)極氧化膜的生長(zhǎng)過(guò)程是在膜的增厚和溶解這一矛盾過(guò)程中展開(kāi)的。通電瞬間，由于氧和M的親和力特別強(qiáng)，在M表面迅速生成一層致密無(wú)孔的氧化膜，它具有很高的絕緣電阻，稱之為阻擋層。由于在形成氧化M時(shí)體積要膨脹，使得阻擋層變得凹凸不平，在膜層較薄的地方，氧化膜首先被電解液溶解并形成空穴，接著電解液變通過(guò)空穴到達(dá)M基體表面，使電化學(xué)反應(yīng)能夠繼續(xù)進(jìn)行，孔隙越來(lái)越深，阻擋層便逐漸向M基體方向擴(kuò)展，即得到了多孔狀的氧化膜。39半導(dǎo)體材料及器件工藝技術(shù)（五）1刻蝕技術(shù)化學(xué)刻蝕、離子刻蝕、反應(yīng)離子刻蝕2半導(dǎo)體材料及器件的測(cè)試40DryEtchingDryetchingmethodsGlowdischargemethodsDryphysicaletching(Sputteretching)PlasmaassistedetchingDrychemicaletching(Plasmaetching)Reactiveionetching(RIE)IonbeammethodsIonmillingReactiveionbeametchingChemicalassistedionmillingCommonmaterialstodryetchSi,SiO2,Si3N4,Al,W,Ti,TiN,TiSi2,PhotoresistDifficultmaterialstodryetchFe,Ni,Co,Cu,Al2O3,LiNbO3,etc.41RF-poweredplasmaetchsystemRF-poweredplasmaetchsystem42Barrelplasmasystem43444546Etchantsandetchproducts47PlasmaassistedetchingPlasmaassistedetchingsequenceTakeamoleculargasCF4EstablishaglowdischargeCF4+eCF3+

F+e RadicalsreactwithsolidfilmstoformvolatileproductSi+4F

SiF4Pumpawayvolatileproduct(SiF4)48PhysicalEtching?Notveryselectivesinceallmaterialssputterataboutthesamerate.?Physicalsputteringcancausedamagetosurface,withextentandamountofdamageadirectfunctionofionenergy(notiondensity).IonEnhancedEtching?Thechemicalandphysicalcomponentsofplasmaetchingdonotalwaysactindependently-bothintermsofnetetchrateandinresultingetchprofile.?FigureshowsetchrateofsiliconasXeF2gas(notplasma)andAr+ionsareintroducedtothesiliconsurface.Onlywhenbotharepresentdoesappreciableetchingoccur.?Etchprofilescanbeveryanisotop