TiN/TiCN multilayer films modified by argon plasma treatment

TiN/TiCN multilayer films were deposited under direct current magnetron sputtering, and then were modified by application of an argon plasma process with an 1100 V substrate bias voltage. The combination of X-ray diffraction, field emission scanning electron microscopy and cross-sectional high resolution transmission electron microscopy was used to analyze the change of the film structure after Ar+ ion bombardment. It could be found that with the increase of the treatment time, the interface between the TiN layer and TiCN layer became more and more blurred and the film structure was also denser. Calculations on stress and hardness data had shown that argon plasma treatment considerably enhanced the mechanical properties of the film, which was mainly reflected in the hardness increasing from 21 GPa to 23.2 GPa, due to the creation of dense structure and fine grain. Comparison with original film, plasma-modified film exhibited substantially low friction behaviors and good wear resistance, especially the reduction of friction coefficient of TiN layer. There was a correlation between the excellent tribological properties of the film and the alteration of the film structure.