Evaporation processes

Historically, evaporation was one of the first processes for depositing pure and high-performance coatings. Most commonly, the process (namely evaporation of the coating material and subsequent condensation on the surface to be coated) is performed under vacuum to keep the material free from oxygen and moisture.
Mostly the evaporated material is resistively heated in a boat or a tungsten coil. High boiling point materials such as quartz are evaporated by e-beams, usually.

Good ol’ evaporation has lost a bit attention these days because of more recent pocesses such as sputtering and Plasma-CVD (Chemical Vapour Deposition) or ALD (Atomic Layer Deposition). But still, it is one oft he most common operations in thin film deposition:

  • Evaporation still is the standard techique for manufacture aluminium mirror coatings for lighting reflectors or anti reflex coatings on eye glass lenses and other optical components.
  • It is the technique of choice to deposit polymers for coatings without destructing them. This plays a role for „Easy-to-Clean“ or „Anti-Fog“ coatings.
  • In further development of „Plasma Polymerization“, Plasma CVD or ALD
    evaporation of the precursor material is a key aspect because it must be transferred into the gas phase in a controlled way before it is reacted there or at the respective surface.

For these reasons, Surface Chemistry is developing specific evaporation devices.