Influence of flow ratio on mechanical and tribological properties of hydrogenated carbon nitride films prepared by DC-RF-PECVD

Abstract

Amorphous hydrogenated carbon nitride (a-CN : H) films were deposited onto silicon (n-100) substrates by dual direct current radio frequency plasma enhanced chemical vapour deposition with CH4 and N2 as feedstock at different ratios. The composition and surface morphology of the films were characterized by means of x-ray photoelectron spectroscopy, Raman spectroscopy and atomic force microscopy; while the mechanical and tribological properties of the films were evaluated using nano-indentation and the UMT test system. It was found that the deposition rate of the films decreased significantly but the N/C ratio, the surface roughness and the ID/IG ratio of the films increased as the N2/CH4 flow ratio increased. The nano-hardness and adhesion strength of the films to the silicon substrate sharply increased at first and then decreased with increasing N2/CH4 flow ratio. Moreover, the wear resistance of the films varied with the N2/CH4 flow ratio. The structure transformation from an sp3-like to sp2-like carbon–nitrogen network in the deposited films was also revealed.