Physical properties and microstructure of sputter deposited aluminum and zirconium oxynitride multilayers

A study of ZrON/AlON multilayers produced by reactive closed field unbalanced DC magnetron sputtering is presented. These multilayers, studied principally for their thermal and mechanical properties, are formed by depositing alternating aluminum and zirconium oxynitride layers over a Mo/MoN/MoZrAlN/oxynitride interface. The multilayer period (Λ) ranges from approximately 2 to 50 nm. After the deposition the coatings were thermally treated in air at 700 °C for 2 h to test their oxidation behaviour. X-Ray reflectivity (XRR) and TEM measurement has been used to determine the multilayer period. The composition of the layers and of the interfaces before and after the thermal treatments were investigated by ion beam analysis (RBS and n-RBS and nuclear reaction analysis). X-Ray diffraction (XRD) and bi-dimensional XRD (XRD2) analyses have been performed to investigate the multilayer micro-structure before and after the thermal treatments. The hardness of the layers has been measured by means of nano-indentation and correlated to the period of the multilayer and to the composition and microstructure. The oxidation of the films is found to depend on the multilayer period. The layers showed good toughness and adhesion before and after the thermal treatments.