Oxidation behavior of titanium nitride films

The oxidation behavior of titanium nitride (TiN) films has been investigated by using x-ray diffraction, Raman scattering spectroscopy, and field emission scanning electron microscopy. TiN films were deposited onto Si substrates by using cathodic arc plasma deposition technique. After that, the films were annealed in the air at 500–800 °C for 2 h. The x-ray diffraction spectra showed that $rutile–TiO2$ appeared above 600 °C. The relative intensity of $TiO2$ rapidly increased with temperatures. Only $rutile–TiO2$ was detected above 700 °C. Raman scattering spectra indicated the presence of $rutile–TiO2$ signals above 500 °C. Meanwhile an additional Si peak appeared at 700 °C in Raman spectra, above which only Si peak appeared. Many nano pores were found on the surface of films annealed at temperatures between 600 and 700 °C in field emission scanning electron microscopy, while the granular structure existed at 800 °C. The as-deposited TiN films had an apparent columnar structure. The thin and dense oxide overlayer appeared at 500 °C, and thicker oxide layer existed above 600 °C. The elongated grain structure with many voids existed in the film at 800 °C. These pores–voids might result from the nitrogen release during the oxidation of the nitride. The oxide layer obviously grows inward indicating the oxidation of TiN films belongs to an inward oxidation. The pre-exponential factor and the activation energy of the oxidation were evaluated by Arrhenius-type relation. These values were $2.2×10−6cm2∕s$ and $110±10kJ∕mol$⁠, which are consistent with those reports in the literature.