We have performed a study to optimize the measurement conditions for SIMS analysis of thin HfSiON films with various nitrogen concentrations, prepared by post-nitridation of HfSiOx. In this study of 2.5 nm thick HfSiON films, we have measured SIMS depth profiles of oxygen and nitrogen under 500 eV Cs+ bombardment at approximately 70degrees from the surface normal, similar to those obtained by HR-RBS. Under the same measurement conditions, good correlation between the estimated nitrogen concentration from XPS and the CsN+. secondary ion intensity by SIMS has been observed for nitrogen concentrations less than 15%. (C) 2004 Published by Elsevier B.V.