Lateral Sputtering by Gas Cluster Ion Beams and its Applications to Atomic Level Surface Modification

Abstract

AbstractGas cluster ion beam equipment (max. voltage 30kV) for sputtering has been developed. Cluster ion beams from gaseous materials such as Ar, O2, N2 and compound materials such as SF6, N2O, CO2 can be generated by expanding them through a Laval nozzle into a high-vacuum region. With this equipment sputtering process fundamentals have been studied. One of the unique characteristics of gas cluster ion bombardment is lateral sputtering. This is shown experimentally by measuring the angular distribution of sputtered atoms and is predicted by molecular dynamics simulation. Dependencies of sputtering yield (10-1000 times higher than for the monomer ion case) on cluster ion size and on ion beam energy for different substrate surfaces have been obtained. Examples of surface smoothing (typically less than 1 nm average roughness) on metals, semiconductors and insulators and of surface cleaning are presented.