Monte Carlo simulation of surface smoothing effect by cluster ions

Cluster ion beam exhibits surface smoothing effects even for a very hard material such as diamond and TiN. From the experimental studies, it was found that the sputtering effects with cluster ions are completely different from those with monomer ions. In this work, surface smoothing mechanisms with cluster ions are studied with Monte Carlo simulations. The motions of the atoms in the cluster-ion impact were modeled and Monte Carlo simulations were performed. Since the ejected atoms move only a few nm by one cluster ion impact, the hills and valleys with high spatial frequencies are removed preferentially, and those with low spatial frequencies needs more ion doses to planarize.