Effect of nitrogen flow rate on structural and mechanical properties of Zirconium Tungsten Nitride (Zr–W–N) coatings deposited by magnetron sputtering

The effect of nitrogen partial pressure (pN2) on structural, composition, deposition rate and mechanical properties of Zirconium Tungsten Nitride (ZrxW1 − xNy) thin films have been studied. ZrxW1 − xNy thin films have been deposited on silicon (100) substrates by DC/RF reactive magnetron sputtering. Structure and elemental composition of the deposited ZrxW1 − xNy thin films strongly depend on pN2. XRD analysis shows that for 0.07 Pa ≤ pN2 ≤ 0.17 Pa, ZrxW1 − xNy films exhibit single (fcc) phase, for 0.20 Pa ≤ pN2 ≤ 0.27 Pa, an amorphous phase is obtained and for 0.33 Pa ≤ pN2 ≤ 0.67 Pa reflections corresponding to dual (fcc + hcp) phase have been observed. The phase formation has been confirmed by TEM diffraction patterns. The root mean square roughness of the films varies non-monotonically with increasing pN2. The thickness of the films decreases continuously with increasing pN2. Results of nano-indentation analysis confirm moderate hardness, high wear resistance, high resistance to fatigue fracture and high adhesiveness of ZrxW1 − xNy films. Among all the phases, maximum hardness (~ 24 GPa) and maximum reduced elastic modulus (135 GPa) have been obtained for dual phase (fcc + hcp) film while resistance to fatigue fracture (H3/Er2 ~ 0.87 GPa), wear resistance (H/Er ~ 0.2) and ductility for single phase (fcc) film were found to be maximum. No crack was observed to propagate in the films at a high load of 50 mN. All the films were found to exhibit high adhesion with the substrate surface.