The structural properties of silicon oxynitride films used at the gate dielectrics interface in Power vertically diffused metal oxide semiconductor technologies have been studied by means of X-ray photoelectron spectroscopy. An overall picture of the interface chemistry evolution as a function of the growth parameters in relation to the effects of the postgrowth reoxidation process is reported. The films were grown in an N2O environment at temperatures higher than 900 degrees C and subsequently reoxidized at 1000 degrees C in a dry oxygen environment. The results show that the chemistry of the oxynitride layer progressively changes by moving toward the silicon interface and, after the reoxidation process, the interface chemical configurations are strongly affected by the initial specific oxynitridation process. In particular, the application of the final reoxidation plays a significative role in determining the distribution of the oxidized O-N-Si-2 bonds near the interface. (c) 2008 The Electrochemical Society.