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.