Influence of the substrate-electrode applied bias voltage on the properties of sputtered a-C : H thin films

Highly tetrahedral, hydrogenated amorphous carbon (a-C:H) films have been d eposited using rf sputtering of graphite by a magnetron sputter source in A r/CH4 atmosphere. The deposition rate, the density and the structural prope rties of the deposited films were studied as a function of applied bias vol tage on substrate during deposition. Optical emission spectroscopy was used to diagnose and monitor the plasma discharge. The film structure was studi ed using IR absorption spectroscopy. For all the films, the percentage of s p(3) hydrogen bonding is higher than 80%. The atomic percentage of bonding hydrogen in the films is in the range 40-60% and increases when the applied bias voltage is increasing.