HARD AMORPHOUS HYDROGENATED CARBON-NITROGEN FILMS OBTAINED BY PECVD IN METHANE-AMMONIA ATMOSPHERES

Hard a-C(N):H films were deposited onto Si(100) substrates by r.f. sel f-bias glow discharge in CH4-NH3 atmospheres (NH3 content varying from 0% to 12.5%). The chemical composition of the films was determined by nuclear techniques, and the film structure was monitored by IR and Ra man spectroscopies. The nitrogen incorporation into the films was foun d to be more than four times greater than that previously obtained wit h N, gas as the nitrogen source at the same partial pressure. Nitrogen incorporation up to levels of 11 at.% resulted in a 50% decrease in t he internal compressive stress. Raman spectra showed that nitrogen inc orporation increased the size or number of graphitic domains in the fi lm, while exhibiting smaller changes in the I-D/I-G ratio. IR spectra showed the same trend as observed in N-2-derived films, with an increa sing presence of nitrogen-containing network terminating groups at the expense of C-H groups.