DIAMOND-LIKE CARBON-FILMS GROWN BY VERY HIGH-FREQUENCY (100 MHZ) PLASMA-ENHANCED CHEMICAL-VAPOR-DEPOSITION TECHNIQUE

Diamond-like carbon films were grown by VHF-PECVD technique. Since the self-bias potential developed in a VHF plasma is very low, sufficient ly high negative de voltage was applied to the substrates in order to make DLC film being grown reasonably hard. Also a comparative study of VHF grown films was made with rf (13.56 MHz) discharge grown films (g rown in the same PECVD reactor). This made it possible to investigate the specific effects of excitation frequency while keeping other param eters constant. Deposition rate (r(d)) was found to be about 5 times h igher for VHF grown films. Marginal variation in optical band gap (E(g )) and refractive index (n) were observed in VHF grown films with vari ation in deposition parameters. Maximum value of hardness recorded was 1500 kg/mm(2) in the case of rf and 902 kg/mm(2) in the case of VHF g rown films, within the range of deposition parameters. Stress values w ere in the range 1.7X10(9) -2.9X10(9) Nm(-2) for VHF and 3.6X10(9)-4.6 X10(9) Nm(-2) for rf grown films. (C) 1996 American Institute of Physi cs.