Correlations between the interface states and trap densities, in particular, the defect types that may be more or less strongly involved in power vertically diffused metal oxide semiconductor reliability performances, and the fine interface chemistry of the Ox–N–Siy bonds have been studied. The oxide preparation process is extracted from an STMicroelectronics proprietary standard for low voltage vertically diffused power metal oxide semiconductor field effect transistors with logic level gate driving. The oxynitride films were grown in N2O environment at temperatures equal to or higher than 900 °C and optionally subjected to a 1000 °C short annealing. Informations about the sample stoichiometry and the nitrogen bonding configurations were obtained by means of x-ray photoelectron spectroscopy. The results show that some peculiar linear and antilinear correlations exist between carrier traps across the oxide or at its interface and the amount of specific nitrogen bonding configurations. In particular, the role of the substitutional N(–SiO3)x bond as a marker of the electrical quality of Si/SiO2 interface is highlighted.