Hydrogen-assisted surface reactions during the growth of sputtered a-SiC:H films

Hydrogenated amorphous silicon-carbon alloy films have been prepared by simultaneous RF reactive magnetron sputtering of silicon and graphite in an H₂ + Ar gas mixture. Infrared and Raman measurements have been performed for samples prepared under different conditions. It is found that the intensity of the band related to silicon-carbon vibrations at approximately 760 cm^-1 in the in spectra decreases with increasing quantity of hydrogen in the gas mixture. A model is used which describes the deposition as a three-stage process: sputtering of the target, transport of the sputtered material in the plasma and film growth processes on the substrate. Analysis of the experimental data allows one to conclude that for a carbon content in the films below 20% carbon is mainly incorporated as carbon-related clusters (CH₃) and for a carbon content above 20% hydrogen-assisted desorption of CH₃ and/or CH₄ groups takes place on the substrate, which significantly lowers the carbon content in the films.