The dependence of chemical mechanical polishing (CMP) performance on particle size and particle concentration was examined. Material removal per abrasive particle is a useful parameter in comparing performance of different abrasives. Impact of particle concentration and particle size on removal rate per particle were different for Ta and TEOS films, indicating differences in material removal mechanisms. The dependencies of removal rate per particle on particle size and concentration were compared with predictions of some of the models reported in published literature. None of these models could successfully predict the results. (C) 2004 The Electrochemical Society.