Deposition and mechanical properties of δ-TaNx films with different stoichiometry by DC magnetron sputtering

Abstract

δ-TaNx films with different stoichiometry were deposited by DC magnetron sputtering on Si (100) substrate. Their microstructures and compositions were investigated by XRD, XPS, Raman and HRTEM. The hardness (H), elastic modulus (E), fracture toughness and tribological properties of films were evaluated by the ultra-micro indentation and a ball-on-disk tribometer. The correlation between H/E, H3/E2 and wear rate was discussed. As indicated by the results, the H, toughness of δ-TaNx films can be modified by controlling the variation of stoichiometric (N/Ta ratio). The H decreases from 39.5 to 24.7 GPa with N/Ta ratio increasing from 0.95 to 1.21. Meanwhile, the wear resistance deteriorates with the increase of N/Ta ratio. The film with a sub-stoichiometric shows a higher H/E, H3/E2, a better resistance of cracking and an improved wear resistance. Sound mechanical properties such as high hardness (H ~ 39.5 GPa), toughness (H/E ~ 0.12), resistance to cracking, lower wear rate (4.6 × 10−6 mm3/Nm) are simultaneously obtained from δ-TaN0.95 film.