PVD is the acronym for "Physical Vapour Deposition" comprising three major paths: 1. Vacuum evaporation
2. Sputtering and 3. Arc-evaporation
Conditions: 200-500⁰C, 10^-2-10^-4 Pa.

1. Vacuum evaporation: free mean path distance: 1-100 m - i.e. a line of sight process. By filling the chamber with an inert gas (like Argon) the evaporated target atoms scatter resulting in a more homogenous layer.

2. Sputtering: Electron discharge at ~1000 V → the electrons accelerate in an electric field → the inert gas (Ar) atoms ionize → they accelerate towards the target-cathode → sputtering of targetatoms →  these condensate on the substrate ("sprays" on the substrate).
One can obtain a considerable increase in the rate of ionization if one applies a magnetic field at the target. The field make the electrons spin thus increasing their path of motion parallel to the target and thereby the inization rate. This again leads to an increase in coating efficiency. This is referred to as magnetron sputtering.

3. Arc-evaporation: The evaporation results from the small discharge arcs jumping around on the target material.

The evaporation is instantaneous. Advantages: The target can be placed more freely and a more homogeneous coating is obtained.

Source:

Overfladebehandling - Stål

Efteruddannelse i Materialeteknologi. Kursus S3.

Dansk Teknologisk Institut. Forlaget. 1993.