Deposition of ta-C:H films by r.f. plasma discharges

Abstract

Abstract 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-pressure r.f. discharge is used to minimize ion collisions in the plasma sheath. 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 films 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 subplantation model of Lifshitz et al. and Robertson. The films deviate from the fully constraint non-crystalline network (FCN) model of Angus et al.