SIOXNY FILMS DEPOSITED BY REMOTE PLASMA-ENHANCED CHEMICAL-VAPOR-DEPOSITION USING SICL4

Silicon oxynitride films have been deposited by remote-plasma enhanced chemical vapor deposition using SiCl4 as a silicon source at a substr ate temperature of 250 degrees C. Different mixtures of O-2 and NH3 we re used to obtain different oxynitride compositions ranging from SiO2 to a stoichiometry close to that of silicon nitride. Also the effect o f a hydrogen flow added during the deposition process on the structura l characteristics of the deposited films was studied. The behavior of the LR absorption spectra as well as the refractive index measured by ellipsometry were used to estimate the stoichiometry of the films as w ell as the effect of the different deposition parameters. It was found that the IR spectra show a shift of the characteristic peak associate d with the stretching vibration mode of the Si-O-Si bends toward lower wave numbers as the relative concentration of ammonia was increased w ith respect to oxygen. No double peaks associated with silicon oxide a nd silicon nitride were observed, indicating the formation of a homoge neous alloy. The IR absorption spectra for these films did not show an y presence of O-H or Si-H related peaks. Atomic force microscopy measu rements on these films show that the hydrogen flow added during deposi tion results in a reduction of the film roughness. (C) 1996 American V acuum Society.