Analysis of the interface of hydrogenated amorphous carbon films on silicon by angle-resolved x-ray photoelectron spectroscopy

Abstract

Thin amorphous hydrogenated carbon films were deposited from a methane rf plasma (13.56 MHz) at 68 mTorr on Si(100) substrates both on the powered (negatively self biased) and on the nonpowered (grounded) electrode. The interface was analyzed with angle-resolved X-ray photoelectron spectroscopy. An approximately stoichiometric silicon carbide layer was found at the interface of a hard carbon film produced on the powered electrode. The thickness of the interfacial carbide as estimated from the angle resolved spectra was approximately 7 A, which is much thinner than previously reported by other workers. There was no interfacial silicon carbide formation evident for a soft polymer-like film produced on the grounded electrode. Instead, a submonolayer amount of oxide was detected at the interface of the soft carbon film which showed poor adhesion. Our results indicate that the high energy ions incident on the powered electrode in the rf plasma are responsible for the production of the interfacial silicon carbide and are also likely to be responsible for the good adhesion of the film to the silicon substrate.