The deposition of NbN and NbC thin films by filtered vacuum cathodic arc deposition

Thin films of niobium nitride (NbN) and niobium carbide (NbC) have been deposited onto conducting (1 0 0) silicon wafers by a filtered vacuum cathodic arc system. The influences of the depositing Nb+ energy, nitrogen and methane pressure on the composition structure and mechanical properties have been investigated. The X-ray diffraction data showed that with increasing substrate bias and gas partial pressure there is an increase in the preferred orientation. Both NbN and NbC films were stoichiometric with no detectable change with increasing substrate bias at the working pressure used. The hardness of both types of films was found to saturate at a substrate bias of approximately −100 V and a partial pressure of nitrogen or methane of 0.65 Pa. The maximum hardness was found to be 48.5 and 45 GPa for NbN and NbC, respectively. The compressive stress was found to increase with increasing substrate bias. The compressive stress ranged between 3.0–8.5 GPa for NbN and 2.0–4.5 GPa for NbC. Strong correlation between compressive stress and hardness was observed for both materials.