Infrared optical properties of silicon oxynitride films: Experimental data and theoretical interpretation

Abstract

Films of SiOxNy, with 0.25≲x≲2 and 0<y≲1.52, were prepared by reactive rf-magnetron sputtering. The composition was determined by Rutherford backscattering spectrometry. Spectrophotometric measurements were conducted in the 2.5–50 μm range, and the complex dielectric function ε was extracted by computation. We interpreted ε by considering the vibrational properties of five basic Si-centered tetrahedra, whose relative occurrence was given by the stoichiometry, and using the Bruggeman effective medium theory to average over the different tetrahedra. Theoretical and experimental data on ε were found to agree very well.