Cascade Evolution and Sputtering in Condensed Rare Gases

Abstract

The sputtering of strongly-bonded materials, like metals and semiconductors, by energetic ions can in many cases be understood by the so-called linear cascade theory [1,2]: The projectile ion shares its energy in collisions with target atoms; these recoil from their original positions, collide with other target atoms; etc. Atoms which cross the target surface and are able to overcome the surface barrier, are sputtered. In this approach, the cascade is assumed to be dilute, and collisions between moving atoms can be neglected. It is clear that after some time, practically all particles in the cascade volume have been energized; these then have so small energies, however, that they do not contribute to sputtering.