Influence of substrate bias on the structure and mechanical properties of ta-C: W films deposited by filtered cathodic vacuum arc

Tungsten containing tetrahedral amorphous carbon (ta-C:W) films were deposited by an off-plane double bend filtered cathodic vacuum arc technique from a composite target. Raman spectroscopy and atomic force microscopy (AFM) were used to characterize the film structure and surface morphology. Substrate bending method and nanoindenter were used to determine the internal stress, hardness, and Young's modulus. The influenc e of substrate bias on the surface morphology, structure, and mechanical properties was systematically studied. All the deposited films were very smooth. The internal stress, hardness and Young's modulus for the deposited films increase with increasing substrate bias, reaching the maximum at a substrate bias of -80 V, then decrease drastically with increasing substrate bias to -200 V. Further increase of substrate bias results in the slight decrease of internal stress, hardness and Young's modulus. The correlation between the structure and the mechanical properties of the deposited films was established.