SPUTTERING AND SMOOTHING OF METAL-SURFACE WITH ENERGETIC GAS CLUSTER BEAMS

Sputtering is a process of surface erosion by energetic ions. One of t he remarkable effects of sputtering with cluster ions is surface smoot hing. To understand its mechanism we have developed a computational mo del, which utilizes molecular dynamics (MD) to simulate rapid atomic c ollisions in the central impact zone, and a finite-difference method t o account for processes occurring on a longer time scale over a wider target area. A case of gas cluster of a few hundred Ar atoms impacting a Cu target with energy up to 20 keV has been considered. The MD simu lation has revealed that the atoms ejected from the surface have a sig nificant lateral momentum component (parallel to the surface) which ma y have a major effect on surface morphology. Evolution of surface morp hology under cluster ion irradiation was described by the modified Kur amoto-Sivashinsky equation. Comparison of the simulations with experim ental data shows qualitative agreement. (C) 1998 Elsevier Science S.A. All rights reserved.