Unbiased Physical Vapor Deposition

[jf11235813]

I apologize if this seems ignorant, but I am at a loss and I need some assistance. I recently built a small vacuum PVD system (Ion source, argon, target material, substrate cradle, etc.) and was showing it to a colleague when it was noticed that my system was unbiased. It actually didn't occur to me to bias the system when I was building it, but my substrate cradle is made from an insulator so it is definitely unbiased. My question is, how is it that it works?? Because it definitely works; I get a good coating on every substrate I sputter. Any help?

 

[Larry Stelmack]

If you are doing ion beam sputtering deposition, i. e. by aiming the ion source at the target, then the sputtered atoms reaching the substrate from the target will have an average kinetic energy that is generally more than enough (several eV) to form a bond with substrate surface atoms, but not enough energy to remove a significant amount of substrate atoms. So the coating should be pretty well adhered to the substrate, especially if there is a chemical affinity between the coating atoms and the substrate atoms. If you are using the ion beam to presputter the substrate surface before deposition, removing physically and chemically adsorbed impurity atoms, the adhesion should also be considerably removed.

Larry Stelmack lstelmack@alum.mit.edu

 

[jf11235813]

The ion source is actually pointing away from the target. Would you mind if i sent you a simple diagram to better illustrate? I'm not sure if I can explain it well enough.