PREPARATION AND PHYSICAL-PROPERTIES OF RF-SPUTTERED AMORPHOUS FILMS IN THE AL2O3-AIN SYSTEM

Oxynitride amorphous films in the system of Al2O3-AlN were prepared by rf sputtering in the range 0-79 mol% AlN, and their density, refractive index, Young's modulus, Poisson's ratio and dynamic hardness were measured. The atomic ratio of oxygen to nitrogen in the films increased linearly with the partial pressure ratio of oxygen to nitrogen during sputtering. The density and Poisson's ratio decreased monotonicly with AlN content, while the refractive index increased. Young's modulus and dynamic hardness decreased with AlN content below about 50 mol% AlN, beyond which they increased. The compositional dependence was explained by the change of the coordination state of aluminum ions with the nitrogen content, and was confirmed by IR spectra and the molar refractivity.