Influence of the Rapid Thermal Nitriding Process on the Properties of TiN Thin Films Obtained from TiO ₂ Sol–Gel Layers

Titanium nitride (TiN) thin films are of considerable interest due to their combination of mechanical hardness, chemical stability, electrical conductivity, and optical performance. Beyond conventional deposition methods such as physical and chemical vapor deposition, TiN can be obtained by nitridation of titanium dioxide (TiO2), involving both reduction and nitrogen incorporation. However, this process usually requires high temperatures and long durations in ammonia-rich atmospheres. Rapid thermal processing techniques, such as rapid thermal annealing (RTA), offer a promising route to accelerate this transformation. In this study, sol–gel-derived TiO2 thin films were subjected to RTA nitridation under ammonia flow, with systematic variation of lamp power (10–60%) and number of emission cycles (1–24). The resulting films were characterized by spectroscopic ellipsometry, four-point probe measurements, X-ray photoelectron spectroscopy, and grazing-incidence X-ray diffraction to assess their optical, electrical, and structural properties. The results demonstrate a strong correlation between RTA parameters, nitrogen incorporation, and TiN phase formation. A specific processing was identified that enables the formation of conductive, infrared-reflective TiN layers without compromising surface integrity. These findings confirm that RTA-assisted nitridation provides an efficient and controllable method for producing high-quality TiN coatings suitable for plasmonic and functional applications.