Deposition conditions and composition and structure relationships for nitride carbon films obtained by ECR plasma-assisted CVD and reactive rf magnetron sputtering

Hydrogenated carbon nitride and carbon nitride films were deposited by ECR plasma-assisted CVD (PACVD) and rf reactive magnetron sputtering. Film composition (N/C ratio), growth rate (Vg) and microhardness H were investigated depending on the type (dc or rf) and the level of substrate bias in the range 0 to −200 V. As was revealed, the ion bombardment influences the composition and growth rate of carbon nitride films during their deposition. An increase in rf bias voltage up to −200 V results in a decrease in Vg up to zero, while the dependence of N/C on rf bias value reveals a peak at about −130 to −150 V. Analysis of Raman spectra for both film types indicates a decrease in size of the film-forming clusters and simultaneous arrangement of atoms towards graphite-like structure with increasing ion bombardment intensity. From the resemblance of Vg, N/C and Raman spectra behavior to the variation in ion bombardment characteristics, it can be concluded that the ion bombardment effect reveals common features for two essentially different deposition methods, whereas the film growth mechanisms are strongly different for these deposition techniques and substantially influence the composition and growth rate of the films. The microhardness of CNxHy films increased with increasing ion bombardment intensity, but did not exceed 7000 N/mm2. These effects are related to the film microstructure evolution under the ion bombardment and sp2 nature of the chemical bonds in the film-forming clusters.