Structural and Tribological Properties of Amorphous Carbon Nitride Thin Films Grown by Plasma Enhanced Chemical Vapor Deposition

This paper reports on the effects of nitrogen dilution on the structure, bonding and tribological properties of nitrogendoped amorphous carbon films (a-C:H:N) deposited by r.f. glow discharge from CH4-N2 mixtures on silicon substrates. For different N2 fractions, film structure and chemical composition were examined using Raman spectroscopy and X-ray photoelectron spectroscopy (XPS). The mechanical and tribological properties were investigated by nanoindentation, scratch testing and a tribometer in a ball-on-disk configuration. Structural characterization indicate that progressive graphitization of the films occurs as nitrogen is introduced in the gas mixture. With increasing nitrogen content, a-C:H:N films exhibited generally better tribological and mechanical properties (e.g. lower friction, higher hardness combined with comparable elasticity) compared to those of the amorphous carbon films.