Vapor deposition technologies include processes that put materials into a vapor state via condensation, chemical reaction, or conversion. When the vapor phase is produced by condensation from a liquid or solid source, the process is called physical vapor deposition (PVD).
These processes are typically conducted in a vacuum environment with or without the use of plasma. which adds kinetic energy to the surface (rather than thermal energy) and allows for reduced processing temperature.
The vacuum environment has the following advantages:
• Reducing the particle density so that the mean free path for collision is long
• Reducing the particle density of undesirable atoms and molecules (contaminants)
• Providing a low pressure plasma environment
• Providing a means for controlling gas and vapor composition
• Providing a means for mass flow control into the processing chamber.
Vapor deposition processes add energy and material onto the surface only, keeping the bulk of the object relatively cool and unchanged. As a result, surface properties are modified typically without significant changes to the underlying microstructure of the substrate.