Characterization of C:H:N deposition from CH4/N-2 rf plasmas using optical emission spectroscopy

Abstract

Optical emission spectra ~OES! from CH4/N2 rf plasmas, which are used for the deposition of nitrogen-containing hydrogenated amorphous carbon ~a-C:H:N! thin films, have been characterized. Previously unidentified spectral lines have been assigned to atomic N. Further identified species include CH, H, H2, N2, N2 1, N, and CN. Variations between spectra from the pure CH4 or N2 plasmas and the mixed CH4/N2 plasma are discussed. The enhancement of excited nitrogen species, with the addition CH4 , is attributed to Penning ionization. The observed OES variations of the CH4/N2 plasma with power, pressure, and CH4/N2 ratio are explained in terms of possible reaction mechanisms and their activation, and correlated with preliminary film growth characteristics.

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