Chemical Vapor Deposition Basics

Study Notes

Chemical Vapor Deposition (CVD)

CVD is a deposition of material on a substrate using chemistry, where a chamber encloses the vapor and energy is provided to the system, typically thermally or radiatively.
A precursor is a chemical that causes deposition on the substrate, typically a one or two-component chemical that reacts to form the desired material.
The deposited layer requires a substrate, which can be a wafer or any other substrate, and it sits on a susceptor that holds the wafer during deposition.
Susceptors must have certain characteristics, including cleanliness, to facilitate the deposition process.

Characteristics of CVD Films

CVD is used to deposit high-quality films with very low contamination, which can be epitaxial and single crystalline.
Epitaxy refers to growing single crystalline material on top of an existing single crystalline material, with perfect lattice-matching and large grains with no or few grain boundaries.

Applications of CVD

CVD is used to grow device-grade semiconducting materials, such as high-mobility transistors in modern CMOS fabrication.
CVD is used to grow heterojunctions, such as germanium on silicon or titanium dioxide on silicon, where the deposited layer has a different material than the substrate.
CVD is used to grow high-quality thin films, not necessarily crystalline or epitaxial, such as polysilicon electrodes in CMOS.
CVD is used to deposit dielectrics, such as silicon nitride and silicon oxide, on top of metal or directly on native substrates.

Advantages of CVD

CVD can deposit a very wide range of materials, limited only by the ability to provide a suitable precursor.
Chemists have developed ways to convert virtually every element into a CVD precursor.
Gaseous precursors can be highly purified, providing an added advantage for CVD.

Description

Learn the fundamentals of Chemical Vapor Deposition (CVD), a process of depositing material on a substrate using chemistry. This lecture covers the basics of CVD, including the components of a CVD chamber and the energy sources used.