DEPOSITION OF TA-C-H FILMS BY RF PLASMA DISCHARGES

Diamond-like a-C:H films have been prepared by r.f. plasma deposition by increasing the plasma density using a magnetic field. A low-pressur e r.f. discharge is used to minimize ion collisions in the plasma shea th. We find a maximum hardness of 50 GPa at a compressive stress of 10 GPa and an optical gap of 2.1 eV by varying pressure, magnetic field and r.f. power. The extreme hardness and high optical gap of these fil ms is due to the rather high sp(3) content of 50% in the diamond-like hydrogenated films compared with a-C:H films normally produced by r.f. discharges. The higher sp(3) content can be explained by the subplant ation model of Lifshitz et al. and Robertson. The films deviate from t he fully constraint non-crystalline network (FCN) model of Angus et al .