Deposition of Mechanically Hard Amorphous Carbon Nitride Films with High [N]/([N]+[C]) Ratio

Abstract

Mechanically hard amorphous carbon nitride films were prepared by a combination of radio frequency (RF) bias voltage applied to a substrate and chemical vapor deposition using a decomposition reaction of BrCN with a microwave discharge flow of Ar. A pulsed operation of the negative RF bias voltage (- V RF ) was applied to avoid excess sputtering of the film. The [N]/([N]+[C]) ratios of the films were ≈0.5 irrespective of the application of - V RF . The maximum hardness was 36±10 GPa for the film obtained under the conditions of - V RF =100 V, a pulse period of 1000 s, and a pulse-on time of 800 s. According to the IR spectra, the intensity of the stretching vibration of the C–N bond was increased by the application of - V RF . The Raman spectra showed increases in the relative intensity and width of the D-band. From these observations, the mechanism of film hardening when - V RF is applied was discussed.