Hydrogenated Carbon-Nitrogen Films Obtained by PECVD using Acetylene and Nitrogen as Precursor Gases

Abstract

Amorphous hydrogenated carbon-nitrogen films were deposited by plasma enhanced chemical vapor deposition (PECVD) using acetylene-nitrogen mixtures. The atomic composition and density of the films were determined by Rutherford backscattering spectrometry (RBS) and elastic recoil detection (ERDA). Raman and Infrared spectroscopies monitored their structure. The addition of nitrogen gas to the deposition atmosphere resulted in a decrease in the film deposition rate. The increase of the nitrogen content is accompanied by the reduction of the carbon content. The IR absorption spectra show an increase intensity of the C=N Raman band and the N-H and C≡N stretching bands. On the other hand, the IR results show a decrease in the intensity of the C-H stretching band. Raman results suggest an increase with the nitrogen content of the fraction of carbon atoms in a sp² state of hybridization with the nitrogen content. The internal compressive stress has been measured by the determination of the bending of the substrate; a reduction of up to 50 % has been observed depending on the nitrogen content.