Effect of copper content and substrate bias on structure and mechanical properties of reactive sputtered CrCuN films

The CrCuN films with various Cu contents were deposited under different substrate bias by DC magnetron sputtering. The influence of Cu content and substrate bias was examined with regard to the microstructure, morphology, and mechanical properties of these films. The CrCuN films containing low Cu content (3.4 at.%) present distinctive columnar growth. Their preferred orientations change from (1 1 1) (−50 V bias) to (2 0 0) (−200 V bias) and surface morphology changes from porous to granular structure with increasing bias. However, when the copper content is increased to 15 at.%, CrCuN films remain (2 0 0) preferred growth independent of bias, while the film maximum hardness is reduced from 32 GPa to 20 GPa because of excess soft metal.

Research highlights▶ We change the copper content in magnetron sputtered CrCuN films by adjusting alloy targets, not by altering process conditions such as substrate bias, and thus we can get the real effect of copper content on CrCuN films. ▶ The combine effect of Cu content and substrate bias on CrCuN films is considered in the manuscript. ▶ The TEM observation combined with the XPS results shows that no amorphous phase exists in CrCuN films regardless of Cu content.