Study of Electrical, Mechanical, and Tribological Properties of CrN x Thin Films as a Function of Sputtering Conditions

The influences of chemical composition and deposition power on the electrical, mechanical, and tribological properties of sputtered chromium nitride (Cr-N) thin films that can be used for development of cryogenic temperature sensor are investigated. Cr-N thin films were deposited by DC reactive magnetron sputtering technique under various nitrogen gas flows (5-20 sccm) and deposition powers (200 and 250 W). Results of chemical composition showed that films produced with 5 and 10 sccm flow of nitrogen gas were substoichiometric, while at higher flows they were overstoichiometric. The surface morphology investigation showed that grains size and surface roughness increase with nitrogen gas flow, whereas deposition power has an inverse effect on both of these parameters. The electrical results demonstrated that the substoichiometric films had a positive temperature coefficient of resistivity, and the overstoichiometric films showed a negative temperature coefficient of resistivity. The films produced at higher deposition power of 250 W showed higher hardness and lower friction coefficient and scratch volume, while variation of nitrogen gas flow in the range of 5-20 sccm did not affect these properties, significantly.