Silicon carbon nitrogen films were deposited on Si (111) substrate by hot filament chemical vapour deposition technique with a gas mixture of silane, methane and nitrogen. The X-ray diffraction pattern and SEM of the as prepared films indicated that they are new material, which is composed of sharp featured particles. The chemical composition and bonding structure of as deposited films were investigated by X-ray photoelectron spectroscopy, auger electron spectroscopy and Fourier transform infrared spectroscopy. These results show that the atomic concentrations of the three elements remain stable and consistent from the surface to the interior, and the atomic concentrations are 45?91, 31?48 and 22?61% respectively. Moreover, the as formed Si-C, Si-N, C;N, C5N and C-N chemical bonds suggest the layer is SiC X N Y . The results above testify that the thin films prepared by this process are the new SiC X N Y material, in which the atomic concentrations of the elements are uniform and stable.