Effect of substrate bias on structure and properties of W incorporated diamond-like carbon films

W incorporated diamond-like carbon (W-DLC) films were deposited on silicon (100) wafers by a hybrid deposition method combining ion beam deposition of carbon with DC magnetron sputtering of tungsten. During the films deposition, a wide range of negative bias voltage from 0 to -600 V was applied. W concentration in the film could be controlled by varying the Ar/C6H6 ratio in the supplying gas. In the present experimental condition, WC1-x, nano-sized particles were not observed in the amorphous carbon matrix. Regardless of the W concentration in the film, it was found that the G-peak position of the Raman spectra had a lowest value at a bias voltage of -200 V, which represents the highest sp(3) bond fraction in the film. The highest residual stress, hardness and Young's modulus were also observed when the bias voltage was -200 V. This result shows that the mechanical properties of W-DLC films were mainly dependent on the atomic bond structure of carbon. On the other hand, the electrical resistivity significantly decreased by the W incorporation.