ON THE HARDNESS OF A-C-H FILMS PREPARED BY METHANE PLASMA DECOMPOSITION

Hard, thick, and almost stress foe a-C:H films prepared by methane pla sma decomposition are reported. The films were prepared on the cathode electrode of a conventional r.f.-sputtering system in the - 100 to - 1200 bias voltage range. The properties of films were determined using optical transmission spectroscopy, Raman spectroscopy, hardness, and stress measurements. Films with high bardness (18 GPa) and very low st ress (0.7 GPa) were obtained. It is proposed that the network rigidity of the films with low stress is mainly maintained by a matrix of disp ersed sp(3) sites, in addition to some contribution of the sp(3) C-C s ites. The stress versus bias voltage dependence supports the subimplan tation model, indicating that it also explains the origin of stress in films prepared by r.f. plasma decomposition. (C) 1998 Elsevier Scienc e S.A. All rights reserved.