Effects of ammonia plasma treatment on the electrical properties of plasma-enhanced chemical vapor deposition amorphous hydrogenated silicon carbide films

Abstract

Amorphous hydrogenated silicon carbide (a-SiC:H) films were deposited from a mixture of silane and methane gases using the plasma-enhanced chemical vapor deposition (PECVD) process. The properties of the film. following ammonia plasma treatment, are reported. A lower silane flow rate reduces the refractive index, but increases the carbon content and the optical band gap. Increasing the carbon concentration of the a-SiC:H films reduces the dielectric constant. The films were treated with ammonia plasma for various treatment periods. The original Film has a smooth surface with a roughness of 0.231 nm but increasing the ammonia plasma treatment period gradually roughens the surface. The chemical bonding nature of the a-SIC:H films with higher silicon content was investigated by X-ray photoelectron spectro.scop, Various nitrogen ioni/ation species reacted with Si to promote the formation of silicon nitride. As a result, although the dielectric constant of the a-SiC:H films, increased slightly, the leakage current density declined as the ammonia plasma treatment time increased.