Synthesis and physicochemical characterization of silicon oxynitride thin films prepared by rf magnetron sputtering

SiO(x)N(y) thin films deposited by rf magnetron sputtering to realize low-loss optical multilayers have been studied. We have analyzed the variations of the optical and physicochemical properties of oxynitride layers according to the deposition parameters: the gas partial pressures, the rf power, and the target composition. A linear variation of the layer refractive index as a function of the oxygen partial pressure was observed as well as a strict substitution of O atoms by N atoms. Thanks to IR spectrophotometric analyses, a model of the oxynitride amorphous structure was proposed and confirmed by Bruggeman and Gained approximation methods. Finally, the absorption level of the oxynitride layers was studied by photothermal deflection spectroscopy.