半导体工艺中所涉及的常用薄膜

Film 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.

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 conducting layers, for diffusion and implantation masks, and for passivation to protect devices from the environment.

…

…MoF 6+SiH 4

MoSi

WF 6+SiH 4WSi

Al, Cu, W……

SiH 4+PH 3+O 2PSG

SiH 2Cl 2+NH 3Si 3N 4

SiH 4+O 2SiO 2

SiH 2Cl 2Epi-Si

SiH 4Poly-Si

半导体工艺中所涉及的常用薄膜：

（PSG = Phospho-Silicate Glass)

There are two major classifications of deposition techniques each having its own subset of related

techniques:

Deposition Method:

Sputtering (溅射）

Evaporation (蒸发）

CVD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：

1、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：

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+ 12H2

CVD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 (200-500°C)

—中温CVD（500-1000°C)

—高温CVD（1000-1300°C)

—常压CVD

—低压CVD

—热CVD

—等离子体CVD

—光CVD

等等

热CVD系统：

electrode electrode

insulator heater r.f power

Plasma: neutrals, ions, electrons T (electron)=1-8eV (10000-80000K)T(ion)=500-1000K 等离子体CVD

The major problem that affects all types of deposition is STEP COVERAGE. It occurs when the film being deposited, does not adhere 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 method of deposition must be inexpensive with a large throughput.

Molecular Beam Epitaxy(MBE)

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 epitaxial 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。