Fabrication of Amorphous Carbon Nitride Films with High [N]/([N]+[C]) Ratios Using the Plasma Chemical Vapor Deposition of the Gas Mixture of C₂H₂ with N₂ : The Possibility to obtain the [N]/([N]+[C]) Ratio of >0.5

Hydrogenated amorphous carbon nitride films with the high [N]/([N]+[C]) ratios of >0.5 were fabricated using the microwave (MW) plasma chemical vapor deposition (CVD) of the gas mixture of N₂ with a trace amount of C₂H₂. This gas mixture was excited by a MW discharge (2.45 GHz, 50-150 W). The partial pressures of them were in the ranges of 26-266 Pa and 2.7-13.3 Pa with the deposition time of 1 h. The X-ray photoeletron spectra (XPS) were measured for the films etched with the Ar-cluster ion beams. Under the deposition conditions of the partial pressures of N₂ and C₂H₂ of 26 Pa and 2.6 Pa, respectively, the [N]/([N]+[C]) ratios of the film surface (without etching) were 0.15-0.49, and those of the film inside (with etching) 0.16-0.55, both of which were the increasing functions of the MW power. The ratios of [N]/([N]+[C])>0.5 were obtained for the inside of the films formed under the conditions of the MW power of >100 W. From the decomvolution analysis of the high-resolution XPS profiles of the C(1s) and N(1s) spectra, the network structure of films was converted from C-C to C-N. As a result, the [N]/([N]+[C]) ratios of >0.5 may be possible for the inside of the films obtained with suppressing the partial pressure of C₂H₂ compared with that of N₂ and with the MW power of >100 W.