Texture development in Ti–Si–N nanocomposite thin films

Nanocomposite thin films of titanium silicon nitride were deposited by sputtering on R-plane sapphire substrates. The effects of silicon addition and negative substrate bias on the texture development of the films were studied systematically by varying the bias voltage in the range −20 to −200 V. The accompanying changes in the microstructure and growth morphology of the phases in these films were investigated in detail using X-ray diffraction and a atomic force microscopy. In addition, the effect of texture on the mechanical properties of the films was also investigated using nanoindentation technique. Pure TiN films deposited without Si exhibit a strong (1 1 1) preferred orientation, while with addition of Si, the orientation of the films changes from (1 1 1) to (2 0 0). Meanwhile the surface morphology of these films changed from a pronounced columnar microstructure to a dense, fine-grained structure. The effect of negative substrate bias voltage applied during deposition also resulted in a similar change of film orientation and microstructure and leads to the increase in hardness of the films from 21 to 40 GPa, respectively.