Effect of N2 gas injection parameters on structure and properties of TiN thin films prepared by reactive gas pulse sputtering

TiN thin films were deposited by reactive gas pulse (RGP) sputtering approach as a function of the amplitude Γ and the velocity v of N2 gas injection. Hybrid architecture of compositionally graded and multilayered structures in the RGP-TiN films was observed in a wide window of N2 gas injection parameters. This hybrid structure consisted of Ti-phase and TiN-phase sublayers, where the former sublayer possessed compositional gradient structure and the latter one maintained constant stoichiometric ratio of Ti:N. Then the effect of the injection parameters on the structure and properties of the films was explored. The phase structure of the films remained stable in a moderate range of Γ and v, but large v induced a transition of from (111) to (200) orientations in the TiN-phase sublayer and smaller Γ yielded a single-layered Ti-phase film. Increasing Γ led to a decrease in the modulation ratio σ and an increase in the modulation period Ʌ of the films, while both σ and Ʌ decreased with increasing v. Meanwhile, the nanohardness H and the electrical resistivity ρ of the films increased with the increase of Γ or v, which was related to the thickness ratio of Ti-phase to TiN-phase sublayers. The correlation between the injection parameters, structure and properties of RGP-TiN films was discussed in detail.