What is Vacuum Evaporation
Vacuum evaporation is a PVD process in which material from a thermal vaporization source reaches the
substrate without collision with gas molecules in the space between the source and substrate. The trajectory
of the vaporized material’s “ Line-of - sight .” The vacuum environment also provides the ability to reduce
gaseous contamination in the deposited film.
Advantages of Vacuum Evaporation
1. High-purity films can be deposited from high-purity source material.
2. Source of material to be deposited may be a solid in any form and purity.
3. The line-of-sight trajectory and “ limited-area sources ” allow the use of masks to define areas of deposition.
4. Deposition monitoring and control are relatively easy.
5. Probably is the least extensive of the PVD processes.
Disadvantages of Vacuum Evaporation
1. Many alloy compositions and compounds can only be deposited with difficulty.
2. Line-of-sight and limited-area sources result in poor surface coverage on complex surfaces without proper substrate fixturing and movement.
3. Line-of-sight trajectories and limited-area sources result in poor film thickness uniformity over large areas.
Film properties depend on the “ angle-of-incidence” of the flux of depositing material.
4. Substrate fixturing with movement capability is necessary to improve surface coverage and thickness uniformity.
5. Few processing variables are available for film property control.
6. Source material utilization may be poor.
7. High radiant heat loads can exist in the deposition system.
Vacuum Evaporation Applications
Vacuum Evaporation is used in form optical interference coatings, mirror coatings, decorative coatings, permeation barrier films on flexible packaging materials, electrically conducting films, and corrosion-protective coatings.
