Effect of substrate bias on properties of HiPIMS deposited vanadium nitride films

We report on the effect of varying the substrate bias on the morphology, composition, structural, and electrical properties of vanadium nitride films deposited by high power impulse magnetron sputtering (HiPIMS). The optimum substrate bias is found to be −50 V, which gives the highest film density, the lowest electrical resistivity, and the lowest surface roughness at the highest deposition rate. We demonstrate how increasing the substrate bias voltage leads to a highly textured film. The preferred orientation of the film changes from (111) to (200) as the substrate bias voltage is increased. An X-ray pole scan shows that the (111) plane grows parallel to the SiO2 substrate when the substrate is grounded while it is gradually replaced by the (200) plane as the substrate bias voltage is increased up to −200 V. The lowest electrical resistivity is measured as 48.4 μΩ cm for the VN film deposited under substrate bias of −50 V. This is among the lowest room temperature values that have been reported for a VN film. We found that the nitrogen concentration presents a decline by 6.5 percentage points as the substrate bias is changed from ground to −200 V.