Electronic structure and mechanical properties of resistant coatings:: The chromium molybdenum nitride system

Cr1-xMoxNy thin films were deposited on silicon by radio-frequency reactive magnetron sputtering. The phase, texture, and residual stress were determined by x-ray diffraction analysis. All the films crystallize in the face-centered-cubic phase. The chemical composition was measured by electron probe microanalysis. Scanning tunneling microscopy revealed a finely grained surface morphology. Scanning electron microscopy showed a columnar crystal arrangement in every film of this study. The binary compounds Mo2N and CrN exhibit grain sizes of about 5 nm, whereas the ternary compounds show grain sizes up to 23 nm. The electronic structure was analyzed using x-ray photoelectron spectroscopy (XPS). The valence band N(2)s and metal d peak separations show a minimum for films with about equal content of chromium and molybdenum. Hardness values, obtained by nanoindentation. exhibit also a pronounced minimum for x=0.4. The similarity between the trends of the XPS peak separation and hardness suggests that the differences in the mechanical properties of the films an mainly due to changes in the bonding character, caused by a different charge distribution between Cr and N. (C) 1999 American Vacuum Society. [S0734-2101(99)05103-9].