Nitrogen doping and thermal stability in HfSiOxNy studied by photoemission and x-ray absorption spectroscopy

Abstract

We have investigated nitrogen-doping effects into HfSiOx films on Si and their thermal stability using synchrotron-radiation photoemission and x-ray absorption spectroscopy. N1s core-level photoemission and NK-edge absorption spectra have revealed that chemical-bonding states of N–Si3−xOx and interstitial N2-gaslike features are clearly observed in as-grown HfSiOxNy film and they decrease upon ultrahigh vacuum (UHV) annealing due to a thermal instability, which can be related to the device performance. Annealing-temperature dependence in Hf4f and Si2p photoemission spectra suggests that the Hf-silicidation temperature is effectively increased by nitrogen doping into the HfSiOx although the interfacial SiO2 layer is selectively reduced. No change in valence-band spectra upon UHV annealing suggests that crystallization of the HfSiOxNy films is also hindered by nitrogen doping into the HfSiOx.