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1、Film DepositionFilm Deposition Deposition is the process of depositing films onto a substrate.There are three categories of these films:* POLY * CONDUCTORS * INSULATORS (DIELECTRICS)Poly refers to polycrystalline silicon which is used as a gate material, resistor material, and for capacitor plates.
2、Conductors are usually made of Aluminum although sometimes other metals such as gold are used. Silicides also fall under this category. Insulators refers to materials such as silicon dioxide, silicon nitride, and P-glass (Phosphorous- doped silicon dioxide) which serve as insulation between conducti
3、ng layers, for diffusion and implantation masks, and for passivation to protect devices from the environment. MoF6+SiH4MoSiWF6+SiH4WSiAl, Cu, WSiH4+PH3+O2PSGSiH2Cl2+NH3Si3N4SiH4+O2SiO2SiH2Cl2Epi-SiSiH4Poly- Si半导体工艺中所涉及的常用薄膜：半导体工艺中所涉及的常用薄膜：（PSG = Phospho-Silicate Glass)There are two major classificat
4、ions of deposition techniques each having its own subset of related techniques:Deposition Method:Sputtering (溅射）Evaporation (蒸发）CVD技术：技术：使用加热、等离子体或紫外线等各种能源，使 气态物质经化学反应（热解或化学合成）形成固态物 质 淀 积 在 衬 底 上 的 方 法 ， 叫 做 化 学 汽 相 淀 积 (Chemical Vapor Deposition)技术，简称CVD技术。它 与真空蒸发和溅射技术并列，是应用较为普遍的一种 薄膜淀积技术。特点：特点： 1、
5、淀积温度低； 2、可以淀积各种电学和化学性质都符合要求的薄膜； 3、均匀性好； 4、操作简便，适于大量生产；CVD的化学反应大致分为两种类型：的化学反应大致分为两种类型：一是一种气态化合物在一定激活能量下被分解，生成 固态物质淀积在衬底上，而其它则为气态物质跑掉， 如： SiH4Si + 2H2另一类是两种气体化合物经化学反应生成新的固态物 质和气态物质，如：3SiH4+ 4NH3Si3N4+ 12H2CVD的分类：的分类：可按淀积温度，反应腔气压或淀积反应的激活方式分类 低温CVD (200-500C) 中温CVD（500-1000C) 高温CVD（1000-1300C) 常压CVD 低压C
6、VD 热CVD 等离子体CVD 光CVD等等热热CVD系统：系统：electrodeelectrodeinsulatorheaterr.f power Plasma: neutrals, ions, electronsT (electron)=1-8eV (10000-80000K) T(ion)=500-1000K等离子体等离子体CVDThe major problem that affects all types of deposition is STEP COVERAGE. It occurs when the film being deposited, does not adhere
7、uniformly to all of the exposed surfaces. Step coverage is usually the biggest problem in metallization, because metal is deposited well into the processing sequence and therefore can not cover the exposed areas uniformly. Deposition techniques must give uniform coverage, repeatable results, and the
8、 method of deposition must be inexpensive with a large throughput.Molecular Beam Epitaxy (MBE) 分子束外延技术分子束外延技术EPITAXY is Greek for arranged upon. It is a process in which a thin crystalline layer is grown on a crystalline substrate. In epitaxial growth, the substrate acts as a seed crystal and the ep
9、itaxial film duplicates the structure (orientation) of the crystal. MBE自1960年开始就有人提出，是一种超精密和极精 确的薄膜生长技术。其利用的是蒸发原理，将分子束 射至单晶衬底上生长单晶外延层的方法。MBE的特点：的特点：?超高真空；设备中外延生长室真空度可达5x10-11Torr, 这样分子平均自由程L较大。 例如：P=10-9Torr, L=5x106cm。 这样大的自由程使分子碰撞几率很小，薄膜生长均 匀，生长速率和组分可精确控制。?可以实现低温过程；这样能减少杂质扩散和沾污的 几率。利用MBE技术可生长出位错密度 direction. The appearance of a random target can be achieved by tilting Si approximately 7 degrees relative to the incoming beam.
