Analysis of charge, mass and energy of large gas cluster ions and applications for surface processing

Abstract

In a previous study averages of +3.2 charges, 64keV energy and 10,400 atoms were measured for a high intensity Ar gas cluster ion beam [D.R. Swenson, Nucl. Instr. and Meth. B 222 (2004) 61]. At this energy multiple collisions with Ar gas atoms are observed to progressively abrade the clusters. The mass loss is consistent with a simple theory that assumes thermalization of the collision energy followed by evaporation. The measurements are important for cluster–surface interactions because they allow cluster energy and dose to be measured for multi-charged clusters. It is shown that higher energy clusters that cause larger craters are more affected by the cluster–gas collisions, and this effect can be beneficial when using a cluster beam to smooth a surface.