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 the TiN thin films. In this study, crystallographic orientation engineering was employed to fabricate epitaxial TiN thin films, with an investigation of the oxidation behavior and electrical conductivity. Epitaxial TiN thin films were grown on the [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. The X-ray photoemission spectroscopy depth profiling directly reflects the oxidation of epitaxial TiN thin films. The oxidation level follows the order of TiN(001) < TiN(110) ≈ TiN(111). X-ray photoemission spectroscopy after Ar+ ion etching reveals the presence of TiNxOy as the oxidation product. As measured by the Current-voltage curve, 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.