1、 Semiconductor materials Lecturer: Aimin Liu & Weifeng Liu劉愛民 劉維峰 半導體資料及器件工藝技術(shù)四1 噴霧熱解成膜技術(shù)噴霧熱解成膜技術(shù)2 CVD成膜技術(shù)成膜技術(shù)低壓低壓CVD、常壓、常壓CVD、離子加強型、離子加強型CVD、MOCVD3 分散及陽極氧化技術(shù)分散及陽極氧化技術(shù)超聲噴霧熱分解安裝表示圖 aUndoped ZnO film surface and cross section100nm100nm(b) N-In codoped ZnO film surface and cross section100nm100nmCV

2、D薄膜生長CVD 爐體設計CVD SYSTEMGas Flow ControlnRegulatornFlow meternMass flow controllerCVD CVD 爐爐管管內(nèi)內(nèi)的的氣氣流流CVDCVD化學反響化學反響Disproportionation irreversibleAsCl3(g) 3Ga(s) 3GaCl(g) 1/4 As4(g)3GaCl(g) 1/2 As4(g) 2GaAs(s) GaCl3(g)Disadvantages: multizone furnacelow gas flowlow reaction efficiency (66%)system co

3、ntamination (hot wall)CVDCVD化學反響化學反響Pyrolysis irreversibleHydride reaction, SiH4(g) Si(s) 2H2(g)Metal-organic reaction MOCVD(CH3)3Ga(g) AsH3(g) GaAs(s) 3CH4(g)Advantages: low growth temperaturecold wall reactorDisadvantage: chemical purity and cost氣體的分散及外表反響Low-Pressure CVD SystemPlasma-Enhanced CVD

4、以不同法成長Si3N4之比較PECVDPECVD、LPCVDLPCVD、APCVD APCVD 之比之比較較The MOVD growth system Vacuum andExhaust systemGas handle systemComputerControlReactorMOCVD Growth SystemReactor-1Aixtron Model-2400 reactorVapor pressure of most common MO compounds Compound P at 298 K(torr)A B Melt point (oC)(Al(CH3)3)2TMAl14.2

5、278010.4815Al(C2H5)3 TEAl0.041 362510.78-52.5Ga(CH3)3 TMGa238 18258.50-15.8Ga(C2H5)3 TEGa4.79 25309.19-82.5In(CH3)3 TMIn1.7528309.7488In(C2H5)3 TEIn0.3128158.94-32Zn(C2H5)2 DEZn8.5321908.28-28Mg(C5H5)2 Cp2Mg0.05355610.56175Logp(torr)=B-A/T Horizontal MOVPE ReactorMOVPE Reactor 分散系統(tǒng)表示框圖1.氫氣入口；2.氫氣出口；

6、3.石墨舟；4.參與爐管；5.抽氣口；6.分子泵；7.機械泵。 分散系統(tǒng)表示框圖石墨分散舟構(gòu)造圖Structure of graphite crucibleSchematic 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 n陽極氧化n陽極氧化膜的構(gòu)成機理:n電極反響：金屬M的陽極氧化，首先是電解水。在電解液中，n通電后在電流作用下發(fā)生水解，同時在陰極放出氫氣。nH2OH+ +OH-n陰極 6H+ 6e3H2n陽極 6OH- 6e3H2O 3On 2M 3O M2O3 n陽極氧化膜的生長過程是

7、在膜的增厚和溶解這一矛盾過程中展開的。n通電瞬間，由于氧和M的親和力特別強，在M外表迅速生成一層致密n無孔的氧化膜，它具有很高的絕緣電阻，稱之為阻撓層。由于在形n成氧化M時體積要膨脹，使得阻撓層變得凹凸不平，在膜層較薄的n地方，氧化膜首先被電解液溶解并構(gòu)成空穴，接著電解液變經(jīng)過空n穴到達M基體外表，使電化學反響可以繼續(xù)進展，孔隙越來越深，n阻撓層便逐漸向M基體方向擴展，即得到了多孔狀的氧化膜。半導體資料及器件工藝技術(shù)五n1 刻蝕技術(shù)刻蝕技術(shù)n化學刻蝕、離子刻蝕、反響離子刻蝕化學刻蝕、離子刻蝕、反響離子刻蝕n2 半導體資料及器件的測試半導體資料及器件的測試Dry EtchingnDry etch

8、ing methodsnGlow discharge methodsnDry physical etching (Sputter etching)nPlasma assisted etchingnDry chemical etching (Plasma etching)nReactive ion etching (RIE)nIon beam methodsnIon millingnReactive ion beam etchingnChemical assisted ion millingnCommon materials to dry etchnSi, SiO2, Si3N4, Al, W,

9、 Ti, TiN, TiSi2, PhotoresistnDifficult materials to dry etchnFe, Ni, Co, Cu, Al2O3, LiNbO3, etc.RF-powered plasma etch systemRF-powered plasma etch systemBarrel plasma systemEtchants and etch productsSolidEtch gasEtch productSi, SiO2, Si3N4PSG, and BPSGCF4, SF6, and NF3SiF4SiCl2 and CCl2F2SiCl2 and

10、SiCl4AlBCl3, CCl4, Cl2Al2Cl6 and AlCl3Organic solidsPhotoresists, etc.O2O2 + CF4CO, CO2, H2OCO, CO2, HFRefractory metals(W, Ta, Ti, Mo, etc.)CF4WF6 .GaAs, InPCl2 and CCl2F2GaCl3, AsCl5, .Plasma assisted etchingnPlasma assisted etching sequencenTake a molecular gas nCF4nEstablish a glow dischargenCF4

11、+e CF3 + F + e nRadicals react with solid films to form volatile productnSi + 4F SiF4 nPump away volatile product (SiF4 ) MaskMaskFilmFilm+ + +Ionic speciesIonic species+ + + + + + +Physical Etching Not very selective since all materials sputter at about the same rate. Physical sputtering can cause

12、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 b