Effects of crystal orientations on oxidation of epitaxial TiN thin films

As an industrial-grade electrode material, TiN is widely employed as a gate electrode and capacitor material in advanced semiconductor devices. However, the inevitable oxidation plays a negative role in TiN thin films. In this study, crystallographic orientation engineering was employed to fabricate epitaxial TiN thin films, investigating their oxidation behavior and electrical conductivity. Epitaxial TiN thin films were grown on [001]-, [110]-, and [111]-oriented SrTiO₃ substrates under high vacuum. High-resolution X-ray diffraction and transmission electron microscopy confirm the epitaxial relationship and high growth quality. X-ray photoemission spectroscopy depth profiling directly reflects the oxidation of epitaxial TiN thin films. The oxidation level follows the order TiN(001) < TiN(110) ≈ TiN(111). X-ray photoemission spectroscopy after Ar⁺ ion etching reveals the presence of TiN_<i>x</i>O_<i>y</i> as the oxidation product. As measured using current-voltage curves, the epitaxial TiN thin films still retain the electrical conductivity. Our work provides a useful reference for preparing oxidation-controlled epitaxial TiN films by crystallographic orientation engineering and guidance for the design of chemically stable TiN thin film electrodes.