Control of the chemical composition of silicon carbon nitride films formed from hexamethyldisilazane in H2/NH3 mixed gas atmospheres by hot-wire chemical vapor deposition

Abstract

Silicon carbon nitride (SiCN) films were deposited by hot-wire chemical vapor deposition using hexamethyldisilazane (HMDS) as the single source gas diluted in ammonia (NH3) and hydrogen (H2) gas mixtures. The chemical composition of the SiCN films was controlled by adjusting the NH3/H2 flow rate ratio. X-ray photoelectron spectroscopy measurements revealed that the carbon and nitrogen contents of the films were controllable from 10 to 35 at.%, while the silicon content remained almost constant at 45 at.%. Although the homogeneity of the SiCN films deposited using HMDS diluted only with H2 degraded with increasing stage temperature from 400 to 800 °C, it was improved by replacing H2 with NH3. Upon introducing NH3, the nitrogen content increased as carbon content decreased accompanied by the replacement of SiC and CC bonds by SiN, NH, and CH bonds, which led to the deterioration of the mechanical properties of the SiCN films.