It is a chemical vapor deposition process in which the solids recovered from the vapor phase during a chemical reaction are used for coating.
In the CVD process, a substrate is exposed to a vaporized compound containing the appropriate constituents. To obtain the desired material, a chemical reaction is initiated at the substrate surface, which condenses on the substrate.
The CVD process is used to form layers when they cannot be made from the silicon substrate. This is the case, for example, with silicon nitride. The silicon layer is produced by thermal decomposition of gases containing silicon as well as nitride. There are various deposition processes that operate at different pressures and temperatures, such as Atmospheric Pressure Chemical Vapor Deposition( APCVD), LPCVD (Low Pressure) and PECVD(Plasma Enhanced).