Deposition of hydrogenated amorphous CNx film in CH4/N4 RF discharge

Hydrogenated amorphous carbon nitride (a-CNx:H) films were prepared in a CH4/N-2 radio-frequency (RF) plasma with a wide pressure range of 0.02-1.0 torr. The deposition rates, infrared (IR) absorption spectra and photoluminescence (PL) spectra of the a-CNx:H films deposited were measured. The deposition rate depends strongly on both the source gas pressure and the CH4/N-2 composition ratio. When the N-2 content in the plasma was increased, no film deposition occurred at relatively low pressures. In the IR spectra of polymer-like soft films deposited at 1.0 torr, four absorption bands associated with N-H (3200-3500 cm(-1)), C-H (2800-3000 cm(-1)), C=N and/or N=N (2100-2250 cm(-1)), and N-H and/or C=N (1500-1800 cm(-1)) bonds were predominantly observed. For diamond-like hard films obtained at 0.1 torr the absorption intensity of the 2100-2250 cm-l band was extremely low, but for those at 0.02 torr the absorption due to the C=N bond became predominant. Intense PL with a broad band of 1.6-2.5 eV was observed for the polymer-like a-CNx:H films, and the PL intensity increased with increasing N-2 content in the plasma. (C) 1999 Elsevier Science S.A. All rights reserved.