Electronic structure and mechanical properties of hard coatings from the chromium-tungsten nitride system

Cr1-xWxNy films were deposited on silicon by rf reactive magnetron sputteri ng. The phase and texture were determined by x-ray diffraction analysis. Al l the films crystallize in the fee phase. Scanning tunneling microscopy rev ealed a finely grained surface morphology. The grain size decreases with in creasing tungsten content in the films. Quantitative values can be assigned to morphology differences through the measurement of the optical reflectiv ity. Hardness values obtained by nanoindentation, and the packing density s ignificantly increase upon addition of a small percentage of W to CrN. The electronic structure was analyzed using x-ray photoelectron spectroscopy. A s deduced from core level binding energy values (chemical shifts), the W2N and Cr1-xWxN films are more covalent than binary CrN. The higher hardness v alues in W2N and Cr1-xWxN compounds compared to that of CrN are related to their prominent covalent bonding character between the metal and nitrogen i ons. (C) 2000 American Vacuum Society. [S0734-211X(00)10406-8].