Structure and mechanical properties of Mo–N/Cu films produced by inductively coupled plasma reactive sputtering

Mo–N/Cu films were deposited on silicon and steel substrates by inductively coupled plasma sputtering using Mo–Cu alloy targets having different Cu concentrations. The structure and mechanical properties of the Mo–N/Cu films were investigated. The (200)-oriented γ-Mo2N–Cu films were obtained at a nitrogen flow rate higher than 1.5 sccm, whereas metallic films were deposited at a nitrogen flow rate lower than 1 sccm. Cu contents in the films increased from 3 at.% to 8 at.% with corresponding increase in Cu concentrations in the target from 5 at.% to 20 at.%. Hardness of the films varied between 19 and 35 GPa as the Cu concentration and nitrogen flow rate were changed. HRTEM and XPS analyses showed that Mo–N/Cu films consisted of γ-Mo2N grains lower than 10 nm in size and a copper amorphous phase. The minimum value of coefficient of friction (CoF) of the films was 0.17 when the film tested by alumina ball.