Ion-induced processes in the dissociative excitation reaction of BrCN to synthesize mechanically hard amorphous carbon nitride films in the microwave plasma chemical vapor deposition system

High-resolution emission spectra have been observed for the dissociative excitation reaction of BrCN with the microwave-discharge flow of Ar to synthesize mechanically hard a-CNx films. From the analysis of intensity of the CN(B(2)Sigma(+)-X(2)Sigma(+)) emission under the conditions of trapping charged species and the addition of SF6, BrCN is found to be excited via the charge transfer from Ar+ followed by the recombination of BrCN+ with thermal electrons as well as the energy transfer from Ar(P-3(0.2)). The relative intensity of the resonance lines of Ar+ and Ar, IAr+/I-Ar, has been measured under the RF-biased condition. The dependence of IAr+/I-Ar on the RF-bias voltage is found to be strongly correlated with that of the reported hardness of films [Tanaka et al.: Jpn. J. Appl. Phys. 39 (2000) 4148], confirming the proposed mechanism of film hardening by the bombardment of the film surface by Ar+.