I.B.A.D.
Ion Beam Assisted Deposition

The process :
IBAD is a combination of two distinct physical operations: an ordinary Physical Vapor Deposition (PVD) on a substrate and a simultaneous bombardment of the surface with a low energy ion beam.
The bombardment procures a better adhesion of the coating and also a high density for it.It takes place in the vacuum or in a controled atmosphere which can combine with the vapor during the deposition and so procures interesting properties.

Below, the representation of the process with our 3 evaporators and the ion gun :

Interests :

• production of denser coating
• the atmosphere can mix with the evaporant material
• with three evaporators as we have, few different evaporant materials can mix before deposition
• creation of a compositional gradient at the coating-base material interface which increase the adhesion of the coating
• a wide type of materials can be coated (ceramic, metal, polymeric materials...) due to the good adhesion
• no need of increasing the treatment of temperature or following precleaning operation althought it is necessary for the main part of other PVD processes

Disadvantages :
There is many procing variables to control (ion energy, ion to atom ratio, angle of ion beam...). Then, it is difficult to obtain uniform ion beam bombardment over the substrate surface especially because of the angle of the ion beam.The result is better when the surface is flat and we also must take care of the reticular plans of the base material.

Applications :

Our works deals with the optical applications of IBAD.For exemple, danger for users of laser are eye's damages but with a good combination of substrate, evaporant material and atmosphere, one can fabricate a dielectric mirror only few micrometre thick, with refleactivity greater than 99% at a design wavelenght.Then, if this wavelenght is the laser's one, users of treated glasses will be protected.

BACK