Precursors of a-CNx(:H) films from the decompositions of BrCN and CH3CN with the discharged products of Ar

The decomposition reaction of CH3CN induced by the microwave discharge flow of Ar was applied to the formation of hydrogenated amorphous carbon nitride (a-CNx:H) films. A discussion was developed on whether CN(X2Σ+) radicals are the dominant source of N atoms of films based on the ratios of the fluxes Φa-CN/ΦCN(X) evaluated for the cases of CH3CN and BrCN as the starting materials. The flux of CN(X2Σ+) radicals arrived onto the substrate surface, ΦCN(X), was evaluated from the number density of CN(X2Σ+) radicals determined from the intensity measurement of the laser-induced fluorescence spectrum of the CN(A2Πi–X2Σ+), 4–0 band together with the flow speed measured by the time-resolved emission. The flux of N atoms incorporated into films, Φa-CN, was evaluated from the atomic-composition analysis by XPS and the mass of film. According to the discussions on the difference of the above ratios and on the electron densities in the reaction region, CN(X2Σ+) radicals are suggested to be the dominant N source of a-CNx:H films.

► A novel method is presented to identify the source of N atoms in a-CNx:H films. ► Films were formed from the decomposition of CH3CN in the microwave plasma of Ar. ► The CN(X2Σ+) radical density was evaluated by the LIF spectroscopy. ► The fluxes of N atoms incorporated into films and of CN radicals were evaluated. ► CN(X2Σ+) radicals are confirmed to be the dominant N source of a-CNx:H films.