Influence of nitrogen gas over microstructural, vibrational and mechanical properties of CVD Titanium nitride (TiN) thin film coating

In this experimental investigation, the influence of different N₂ gas flow rates on different properties (e.g. morphological, mechanical, etc.) of chemical vapor deposited (CVD) Titanium nitride (TiN) coatings has been discussed. The TiN coatings had been grown on Si (100) substrate at elevated temperature (1000 °C) using Titanium dioxide (TiO₂) powder. SEM images reveal a dense uniform microstructure with an irregular surface pattern. The surface roughness of the coatings was found to be increased from 12.42 to 28.56 nm with an increase in flow rate. XRD results indicate a B1 NaCl crystal structure of the film with reduced crystallite size with the increasing N₂ flow rate. Through the corrosion test, it has been observed that due to the variation of N₂ flow rate the corrosion resistance of the films decreases with increasing N₂ flow rate. The mismatch of thermal expansion co-efficient in between Si substrate and TiN thin film reduces with higher N₂ flow rate. The acoustic and optic phonon mode of TiN coatings have been shifted to higher intensities with higher N₂ flow rate. The mechanical properties of the film reveal that the maximum value of hardness (H) and Young's modulus (E) are 30.14 and 471.85 GPa respectively.