Synthesis of SIGN thin films on mirror-polished Si(100) substrates has been achieved by performing a bias-assisted hot filament chemical vapor deposition. High purity nitrogen, methane, and hydrogen were used as reactant gases. Incorporated Si element in the films totally came from the Si surface of the substrate. Scanning electron microscopy showed two categories of morphologies of the films according to the introduction of hydrogen. Energy-dispersive X-ray analysis and Auger electron spectroscopy depth profiling were used to measure the chemical composition of the samples. With no hydrogen applied, the film was found to be a nitride layer over the Si substrate with some nanosize columnal silicon-containing C-N crystals embedded. With hydrogen added, the film was uniformly composed of smaller SiCN particles. On both conditions, the overall carbon content was rather limited. X-ray photoelectron spectroscopy revealed the chemical environment of C, N, and Si atoms in the samples. The effect of methane flow ratio and substrate temperature were investigated on the conditions without hydrogen flow. The effects of hydrogen flow ratio on the films were also studied.