Structure and mechanical properties of Ti–Si–N films deposited by combined DC/RF reactive unbalanced magnetron sputtering

Ti–Si–N nanocomposite films with Si content between 0 and 13.5at.% were deposited by combined DC/RF reactive unbalanced magnetron sputtering. The composition, structure, and mechanical properties of the as-deposited Ti–Si–N films were measured by energy dispersive analysis of x rays, x-ray diffraction (XRD), and nanoindentation experiments, respectively. All of the Ti–Si–N films exhibited a higher hardness than pure TiN films deposited under similar conditions. The highest hardness (∼41GPa) was obtained in the film with Si content of about 8at.%. Ti–Si–N films also exhibited a higher resistance to plastic deformation (i.e., higher ratio H3∕E*2) than pure TiN. XRD patterns revealed that the as-deposited films were composed of cubic TiN crystallites with a preferential orientation of (111). With increase of RF power applied to the Si targets, the TiN (111) peak intensity or TiN crystallite size increased in the lower RF power range but decreased in the higher RF power range, showing a maximum at an RF power of 500W (power density ∼1.14W∕cm2), corresponding to a Si content of about 5at.% in the film.