STRESS DEVELOPMENT DURING DEPOSITION OF CNX THIN-FILMS

We have investigated the influence of deposition parameters on stress generation in CNx (0.3<x <0.5) thin films deposited onto Si(001) subst rates by reactive magnetron sputtering of C in pure N-2 discharges. Fi lm stress, sigma, which in all cases is compressive, decreases with an increase in the N-2 pressure, P-N2, due to structural changes induced by the pressure-dependent variation in the average energy of particle s bombarding the film during deposition. The film stress sigma is also a function of the film growth temperature, T-s, and exhibits a maximu m value of similar to 5 GPa at 350 degrees C. Under these conditions, the films have a distorted microstructure consisting of a three-dimens ional, primarily sp(2) bonded, network. In contrast, films deposited a t T-s<200 degrees C with a low stress are amorphous. At 350 degrees C< T-s<600 degrees C, sigma gradually decreases as T-s is increased and t he microstructure becomes mon graphitic and contains fewer defects. Na noindentation measurements show that the films grown at 350 degrees C exhibit the highest hardness and elasticity. (C) 1998 American Institu te of Physics. [S0003-6951(98)01320-5].