###### Abstract  
Titanium nitride (TiN) is a material of interest for electrodes owing to its high-temperature stability, robustness, low-cost, and suitable electrical properties. Herein, we studied the surface morphology and electrical properties of TiN thin film deposited onto an Si/SiO\({}_{2}\) <100> substrate through direct current (DC) sputtering with a high-purity TiN target in an argon-gas environment. The electrical properties and surface morphology of TiN thin film significantly improved with increased source power and decreased working pressure. The improved electrical properties could be attributed to the suppressed secondary phase (Ti\({}_{2}\)N) formation and the reduced electron scattering on smoother surface. Consequently, high-quality TiN thin film with the lowest resistivity (\(\rho\) = 0.1 m\(\Omega\)\(\cdot\)cm) and the smallest surface roughness (RMS roughness, R\({}_{\text{q}}\) = 0.3 nm) was obtained under the optimized condition. The TiN film was further used as the bottom electrode for a metal-insulator-metal (MIM) capacitor. Results demonstrated that the electrical properties of TiN film were comparable to those of noble-metal thin films. Therefore, the TiN thin film fabricated by DC sputtering method had excellent electrical properties and good R\({}_{\text{q}}\), indicating its potential applications in MIM capacitors and Si technology.  
titanium nitride; thin film; surface roughness; electrical properties; magnetron sputtering +
Footnote †: journal: Applied Sciences  
chemical technique always accompanied by a risk of residues being retained from the precursors. The films' impurity content depends on reaction completeness [13]. In physical vapor deposition (PVD) methods, the environment is much cleaner owing to the high vacuum used and the lack of precursor compounds with unwanted elements. The direct current (DC) magnetron-sputtering method was selected for this study because of its many advantages, including low cost, high purity, uniformity, and good control over stoichiometry. Deposition conditions such as argon content in the chamber, power, pressure, residual oxygen in the chamber, substrate temperature, and substrate bias are important parameters for obtaining high-quality TiN thin film in reactive sputtering. [PERSON] et al. reported that as-deposited TiN\({}_{\text{x}}\) resistivity gradually decreases with increased nitrogen flow rate during deposition [14]. [PERSON] et al. fabricated a TiN\({}_{\text{x}}\) thin film on different types of substrate and reported that the resistivity of TiN\({}_{\text{x}}\) film is strongly influenced by substrate temperature, deposition time, working pressure, bias power, and Ar and N\({}_{\text{2}}\) flow rate [15]. [PERSON] et al. showed that thickness and N\({}_{\text{2}}\) concentration strongly affect the electrical, optical, compositional, structural, and morphology properties of TiN thin films [16]. However, further systematic information on the correlation between sputtering process parameters and properties of TiN is required to produce TiN thin films for a low resistivity and optimized MIM structures. Moreover, a comprehensive study on the effects of operating pressure and source power to improve the quality of TiN thin films that can be used as an electrode material in advanced MIM capacitors and IC technologies has not yet been fully resolved.  
Herein, we prepared TiN thin films on an Si/SiO\({}_{\text{2}}\) <100> substrate through the DC magnetron-sputtering method. The effects of source power and working pressure on the roughness surface and resistivity of TiN thin film were studied in detail. Our results demonstrated that the surface roughness and resistivity of TiN thin film can be strongly improved by increasing the source power and decreasing the working pressure. We can obtain high-quality of TiN thin film with low resistivity (0.1 m\(\Omega\)-cm) and small surface roughness (RMS roughness, R\({}_{\text{q}}\) = 0.3 nm) by using 150 W bias power and 0.5 \(\times\) 10\({}^{-3}\) Torr as the optimum sputtering conditions.