We have investigated nitrogen-doping effects into HfSi Ox films on Si and their thermal stability using synchrotron-radiation photoemission and x-ray absorption spectroscopy. N 1s core-level photoemission and N K -edge absorption spectra have revealed that chemical-bonding states of N- Si3-x Ox and interstitial N2 -gaslike features are clearly observed in as-grown HfSi Ox Ny 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 Hf 4f and Si 2p photoemission spectra suggests that the Hf-silicidation temperature is effectively increased by nitrogen doping into the HfSi Ox although the interfacial Si O2 layer is selectively reduced. No change in valence-band spectra upon UHV annealing suggests that crystallization of the HfSi Ox Ny films is also hindered by nitrogen doping into the HfSi Ox.
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