Surface analysis of TiN thin film deposited on silicon (100) by excimer laser

Titanium nitride (TiN) thin films were deposited on hydrogen-terminated silicon substrates by pulsed laser ablation of a ceramic TiN target. A KrF excimer laser with a wavelength of 248 nm and pulse duration of 23 ns was used in our experiments. The vacuum chamber was maintained at a pressure of 10-5 Torr during the deposition and the substrate temperature ranged from room temperature to 600 degrees C. Nano-indentation and scanning tunneling microscopy (STM) were used to analyze the surface properties of the deposited thin films. The hardness, Young's modulus and morphology of the thin films at different substrate temperatures were investigated. The hardness of the thin films deposited at 600 degrees C was found to be as high as 26 GPa and the Young's modulus approximately 280 GPa. This can be explained by x-ray diffraction measurements. The root mean square roughness and the grain size of the thin films deposited at different substrate temperatures were measured by STM in the contact mode. The relationship between the surface morphology and the crystallinity will be discussed. The x-ray diffraction studies indicated that the grain size of the thin films increased with the substrate temperature and a high quality film can be obtained when the substrate temperature reaches 600 degrees C. Clear improvement of the film hardness and Young's modulus resulted from increasing the substrate temperature.