| Summary: | Reactive magnetron sputtering was used to deposit tantalum nitride (Ta–N) thin films on Si substrate. The effect of varying the N2 percentage in the N2/Ar gas mixture on the Ta–N film characteristics was investigated. Mechanical and tribological properties were studied using nanoindentation and pin-on-disc wear testing. Decreasing the N2 content in the gas mixture was found to change the film structure from face centered cubic (fcc) TaN (from 25% to 10% N2) to highly textured fcc TaN (at 7% N2) to a mixture of fcc TaN1.13 and hexagonal Ta2N (at 5% N2), and finally to hexagonal Ta2N (at 3% N2). A high hardness of about 33 GPa was shown by the films containing the hexagonal Ta2N phase (5% and 3% N2). Decreasing the N2 content below 7% N2 was also found to result in microstructural refinement with grain size 5–15 nm. Besides the highest hardness, the film deposited with 3% N2 content exhibited the highest hardness/modulus ratio (0.13), and elastic recovery (68%), and very low wear rate (3.1 × 10−6 mm3·N−1·m−1).
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