We have measured the N profile in HfSiON film using Cs primary ions under various conditions and observed an enhancement of the N ion signal at the surface and interface between HfSiON/Si. We have found that the enhancement is alleviated by glancing angle Cs primary ions and O-2 flooding. Our backside SIMS measurements show that Hf is diffused into the Si substrate from HfSiON film during the thermal processes. (c) 2006 Elsevier B.V. All rights reserved.