Amorphous hydrogenated carbon films: effects of nitrogen and fluorine incorporation on the film microstructure and mechanical properties: a review

The effects on the film microstructure and mechanical properties due to nitrogen and fluorine incorporation into amorphous hydrogenated carbon films deposited by plasma enhanced chemical vapor deposition were reported. The chemical composition was studied by ion beam techniques. The film density was obtained combining the ion beam results and the film thickness determined by profilometry. The modifications on the film microstructure were followed by Raman spectroscopy and the chemical bonding investigated by X-ray photoelectron spectroscopy. Special attention was devoted to the mechanical properties, hardness and internal stress. We found that nitrogen incorporated films retained their diamond-like properties, despite the progressive graphitization upon nitrogen incorporation. In this case, the reduction of the internal stress without substantial changes in the film hardness was attributed to the reduction of network connectivity. The increase of the fluorine content results in polymer-like films, with smaller internal stress and hardness.