Limitation of nitrogen incorporation into the hydrogenated amorphous carbon nitride films formed from the dissociative excitation reaction of CH3CN

High-resolution CN(B(2)Sigma (+)-X(2)Sigma (+))and CH(A(2)Delta -X(2)Pi Phi) emission spectra were observed for the dissociative excitation reaction of CH3CN with the microwave-discharge flow of Ar for synthesizing hydrogenated amorphous carbon nitride (a-CNx:H) films. The simulation analysis of these spectra revealed that the relative number density of CII(A) to that of CN(B), N-CH(A)/N-CN(B), was strongly dependent on the pressure of Ar, P-Ar, in the range of P-Ar = 0.1-0.8 Torr. The P-Ar-dependence of N-CH(A)/ N-CN(B), showed a strongly negative correlation with that of the [N]/([N] + [C]) ratio obtained in our previous structural analysis of the films [Saitoh rt al.: Jpn. J. Appl. Phys. 39 (2000) 1258]. This correlation was fully explained in terms of the consumption of the CN radical by the hydrogen-abstraction reaction from the film surface, preventing the incorporation of the nitrogen atoms into the a-CNx:H films.