半導(dǎo)體材料ppt課件

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,Semiconductor materials,Lecturer: Aimin Liu & Weifeng Liu,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) 2 CVD成膜技術(shù) 低壓CVD、常壓CVD、離子增強型CVD、MOCVD 3 擴散及陽極氧化技術(shù),2,超聲噴霧熱分解裝置示意圖,3,4,5,6,CVD薄膜生長,7,CVD 爐體設(shè)計,8,CVD SYSTEM,9,10,11,Gas Flow Control,Regulator Flow meter Mass flow controller,12,CVD 爐管內(nèi)的氣流,13,CVD化學(xué)反應(yīng),Disproportionation irreversible AsCl3(g) ＋3Ga(s) ? 3GaCl(g) ＋1/4 As4(g) 3GaCl(g) ＋1/2 As4(g) ? 2GaAs(s) ＋GaCl3(g) Disadvantages: multizone furnace low gas flow low reaction efficiency (66%) system contamination (hot wall),14,CVD化學(xué)反應(yīng),Pyrolysis irreversible Hydride reaction, SiH4(g) ? Si(s) ＋2H2(g) Metal-organic reaction MOCVD (CH3)3Ga(g) ＋AsH3(g) ? GaAs(s) ＋3CH4(g) Advantages: low growth temperature cold wall reactor Disadvantage: chemical purity and cost,15,16,氣體的擴散及表面反應(yīng),17,18,19,Low-Pressure CVD System,20,Plasma-Enhanced CVD,21,以不同法成長Si3N4之比較,22,PECVD、LPCVD、APCVD 之比較,23,24,25,26,The MOVD growth system,27,,,,,,,,,,,,,,,,,,,Vacuum and Exhaust system,Gas handle system,Computer Control,,Reactor,MOCVD Growth System,28,Reactor-1,29,Aixtron Model-2400 reactor,30,Vapor pressure of most common MO compounds,Log[p(torr)]=B-A/T,31,Horizontal MOVPE Reactor,32,MOVPE Reactor,33,34,,擴散系統(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.機械泵。,擴散系統(tǒng)示意框圖,35,,石墨擴散舟結(jié)構(gòu)圖 Structure of graphite crucible,36,,,37,,Schematic diagram of Anodic Oxidation equipment,GaSb做陽極，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,陽極氧化,38,陽極氧化膜的形成機理: 電極反應(yīng)：金屬（M）的陽極氧化，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，同時在陰極放出氫氣。 H2O→H+ +OH- 陰極 6H+ 6e→3H2↑ 陽極 6OH-- 6e→3H2O 3[O] 2M 3[O] →M2O3 陽極氧化膜的生長過程是在膜的增厚和溶解這一矛盾過程中展開的。 通電瞬間，由于氧和M的親和力特別強，在M表面迅速生成一層致密 無孔的氧化膜，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，接著電解液變通過空 穴到達M基體表面，使電化學(xué)反應(yīng)能夠繼續(xù)進行，孔隙越來越深， 阻擋層便逐漸向M基體方向擴展，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)體材料及器件的測試,40,Dry Etching,Dry etching methods Glow discharge methods Dry physical etching (Sputter etching) Plasma assisted etching Dry chemical etching (Plasma etching) Reactive ion etching (RIE) Ion beam methods Ion milling Reactive ion beam etching Chemical assisted ion milling Common materials to dry etch Si, SiO2, Si3N4, Al, W, Ti, TiN, TiSi2, Photoresist Difficult materials to dry etch Fe, Ni, Co, Cu, Al2O3, LiNbO3, etc.,41,RF-powered plasma etch system,RF-powered plasma etch system,42,Barrel plasma system,43,44,45,46,Etchants and etch products,47,Plasma assisted etching,Plasma assisted etching sequence Take a molecular gas CF4 Establish a glow discharge CF4+e ? CF3 + F + e Radicals react with solid films to form volatile product Si + 4F ? SiF4 ? Pump away volatile product (SiF4 ?),48,Physical Etching,? Not very selective since all materials sputter at about the same rate. ? Physical sputtering can cause damage to surface, with extent and amount of damage a direct function of ion energy (not ion density).,Ion Enhanced Etching,? The chemical and physical components of plasma etching do not always act independently - both in terms of net etch rate and in resulting etch profile. ? Figure shows etch rate of silicon as XeF2 gas (not plasma) and Ar+ ions are introduced to the silicon surface. Only when both are present does appreciable etching occur. ? Etch profiles can be very anisotopic, and selectivity can be good.,No plasma,sputtering,SILICON VLSI TECHNOLOGY Fundamentals, Practice and Modeling By Plummer, Deal & Griffin,? 2000 by Prentice Hall Upper Saddle River NJ,49,50,Chemical vs. chemical/physical etching,Purely chemical etching (using only reactive neutral species) Isotropic etching,Chemical + physical etching (using reactive neutral species and ionic species) Anisotropic etching,51,? Many different mechanisms proposed for this synergistic etching between physical and chemical components. Two mechanisms are shown above. ? Ion bombardment can enhance etch process (such as by damaging the surface to increase reaction, or by removing etch byproducts), or can remove inhibitor that is an indirect byproduct of etch process (such as polymer formation from carbon in gas or from photoresist). ? Whatever the exact mechanism (multiple mechanisms may occur at the same time): ? need both components for etching to occur. ? get anisotropic etching and little undercutting because of directed ion flux. ? get selectivity due to chemical component and chemical reactions. There are many applications in etching today.,Ion-Enhanced Etching,Chemical component selectivity Physical component anisotropy,,,volatility of byproducts,,Roles of ions:Adsorption, Reaction, Formation of byproducts, removal,SILICON VLSI TECHNOLOGY Fundamentals, Practice and Modeling By Plummer, Deal & Griffin,? 2000 by Prentice Hall Upper Saddle River NJ,52,濺射離子刻蝕原理及斜面刻蝕分析,1. 刻面效應(yīng),2. 再沉積效應(yīng),3. 陰影效應(yīng),53,,54,55,56,表征方法 1. 霍爾效應(yīng)測試 2. X射線衍射方法（XRD） 3. 光致發(fā)光譜（PL） 4. X射線光電子能譜（XPS） 5.其他測試方法：掃描電子顯微鏡（SEM）、采用PMT 920光電倍增 、 DF4810型晶體管特性圖示儀、KEITHLEY 4200 I-V測試系統(tǒng),57,課程總結(jié),半導(dǎo)體材料與工藝課程內(nèi)容共分為五部分,58,半導(dǎo)體材料及器件工藝技術(shù)（一）,1發(fā)光器件材料及工藝技術(shù) 2光伏器件材料及工藝技術(shù),59,1發(fā)光器件材料及工藝技術(shù),60,61,典型的量子阱激光器波導(dǎo)結(jié)構(gòu)示意圖,62,63,2光伏器件材料及工藝技術(shù),64,在織構(gòu)化硅襯底上制備的HIT太陽電池（Heterojunction With Intrinsic Thin Layer）,65,半導(dǎo)體材料及器件工藝技術(shù)（二）,1光刻技術(shù) 2真空鍍膜 3晶體制備及液相外延 4磁控濺射,66,濺射（sputtering）又叫陰極濺射（cathodic sputtering）。濺射鍍膜是一個PVD過程。通過用由稀有氣體在低真空下放電獲得的正離子轟擊置于陰極的固體表面（靶），使固體原子（或分子）從表面射出，進而以一定能量淀積在基片上，形成薄膜。與蒸發(fā)薄膜相比，由于濺射中的靶材料無相變，化合物不易分解，合金不易分餾，因此使用的膜材更為廣泛。在微米/納米技術(shù)中有廣泛的用途。如用于制備金屬膜、合金膜、半導(dǎo)體膜、氧化物、絕緣介質(zhì)膜、化合物半導(dǎo)體膜、碳化物及氮化物，以及超導(dǎo)薄膜等。,濺射鍍膜,67,射頻濺射鍍膜法 在靶陰極上的電位是相對0電位的基片的是一疊加在－4000V負高壓上作射頻變化的電壓。特點：淀積速率高，質(zhì)量較好，幾乎適于所有材料。,磁控濺射鍍膜法 在電場的垂直方向加一磁場，電子在正交電磁場的空間里作擺線運動，大大提高離子流的密度，從而提高濺射效率。是一種理想的方法，已獲廣泛應(yīng)用。,+,-,68,濺射閥值 濺射閥值是指使靶原子發(fā)生濺射的入射離子所必須具有的最小能量。能量較小的荷電正離子并不能立即陰極材料中轟出原子。而只能使它們在其平衡位置加速振動。只有當(dāng)獲得的能量超過其結(jié)合能，才可能從表面被濺射出來。濺射閾值取決于靶材料對于同一周期的元素，濺射閥值隨原子序數(shù)增加而減小。對絕大多數(shù)金屬來說，該值為10~30eV,69,半導(dǎo)體材料及器件工藝技術(shù)（三）,1離子鍍成膜技術(shù) 2分子束外延技術(shù),70,離子成膜法,離子鍍膜法是美國Sandia公司的D.M.Mattox于1963年首先提出來的，它是在真空條件下，靠直流電場引起放電，陽極兼作蒸發(fā)源，基片放在陰極上，在氣體離子和蒸發(fā)物質(zhì)的轟擊下，將蒸發(fā)物質(zhì)或其反應(yīng)物鍍在基電底上。 由于使用離子轟擊基片，可以獲得附著性更好，膜的硬度更高，厚更厚的薄膜。,1-5kV,,,,原子,,離子,71,蒸發(fā)離子鍍,離子鍍是在真空條件下，利用氣體放電使氣體或 被蒸發(fā)物部分離化，產(chǎn)生離子轟擊效應(yīng)，最終將 蒸發(fā)物或反應(yīng)物沉積在基片上。離子鍍集氣體輝 光放電、等離子體技術(shù)、真空蒸發(fā)技術(shù)于一身， 大大改善了薄膜的性能。優(yōu)點是： 1、兼有真空蒸發(fā)鍍膜和濺射的優(yōu)點； 2、所鍍薄膜與基片結(jié)合好； 3、到達基片的沉積粒子繞射性好； 4、可用于鍍膜的材料廣泛； 5、沉積率高； 6、鍍膜前對鍍件清洗工序簡單且對環(huán)境無污染。,,72,成膜原理,在離子鍍的過程中，存在兩種反的過程 其一，淀積作用,,?：淀積速率（?m/min） ?：薄膜密度 g/cm3 M：淀積物質(zhì)的摩爾質(zhì)量 NA：質(zhì)量阿佛伽德羅常數(shù),其二，剝離作用,,j：入射離子形成的電流密度（mA/cm2）,鍍膜條件：n nj,73,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) 2 CVD成膜技術(shù) 低壓CVD、常壓CVD、離子增強型CVD、MOCVD 3 擴散及陽極氧化技術(shù),74,CVD薄膜生長,75,CVD化學(xué)反應(yīng),Pyrolysis irreversible Hydride reaction, SiH4(g) ? Si(s) ＋2H2(g) Metal-organic reaction MOCVD (CH3)3Ga(g) ＋AsH3(g) ? GaAs(s) ＋3CH4(g) Advantages: low growth temperature cold wall reactor Disadvantage: chemical purity and cost,76,CVD化學(xué)反應(yīng),Disproportionation irreversible AsCl3(g) ＋3Ga(s) ? 3GaCl(g) ＋1/4 As4(g) 3GaCl(g) ＋1/2 As4(g) ? 2GaAs(s) ＋GaCl3(g) Disadvantages: multizone furnace low gas flow low reaction efficiency (66%) system contamination (hot wall),77,Plasma-Enhanced CVD,78,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)體材料及器件的測試,79,RF-powered plasma etch system,RF-powered plasma etch system,80,Physical Etching,? Not very selective since all materials sputter at about the same rate. ? Physical sputtering can cause damage to surface, with extent and amount of damage a direct function of ion energy (not ion density).,Ion Enhanced Etching,? The chemical and physical components of plasma etching do not always act independently - both in terms of net etch rate and in resulting etch profile. ? Figure shows etch rate of silicon as XeF2 gas (not plasma) and Ar+ ions are introduced to the silicon surface. Only when both are present does appreciable etching occur. ? Etch profiles can be very anisotopic, and selectivity can be good.,No plasma,sputtering,SILICON VLSI TECHNOLOGY Fundamentals, Practice and Modeling By Plummer, Deal & Griffin,? 2000 by Prentice Hall Upper Saddle River NJ,81,Etchants and etch products,82,Plasma assisted etching,Plasma assisted etching sequence Take a molecular gas CF4 Establish a glow discharge CF4+e ? CF3 + F + e Radicals react with solid films to form volatile product Si + 4F ? SiF4 ? Pump away volatile product (SiF4 ?),83,（六）代表性的幾種半導(dǎo)體材料特性 及表征技術(shù),Elemental semiconductor--Si, Ge Compound semiconductor IV-IV---Si SiC III-V----GaAs,GaSb,InP,InAs, II-VI ---ZnO,ZnS,ZnSe Alloys Binary---Si1-xGex Tenary---AlGaAs,AlInAs, Quaternary---AlGaAsSb,84,表征方法 1. 霍爾效應(yīng)測試 2. X射線衍射方法（XRD） 3. 光致發(fā)光譜（PL） 4. X射線光電子能譜（XPS） 5.其他測試方法：掃描電子顯微鏡（SEM）、采用PMT 920光電倍增 、 DF4810型晶體管特性圖示儀、KEITHLEY 4200 I-V測試系統(tǒng),85,