Structural and optical properties of silicon oxynitride on silicon planar waveguides

Abstract

Planar optical waveguides on thermally oxidized Si(111) substrates have been made with rf magnetron sputtering deposition from a SiO₂ target in a N₂ and Ar reactive atmosphere. Reproducible guiding layers of silicon oxynitride with refractive index in the 1.6–1.9 range have been obtained changing deposition parameters. A detailed study of the film characteristics in terms of optical and chemical properties is reported. The films are a mixture of SiO₂ and silicon oxynitride, with an extended intermixed region at the thermal SiO₂ buffer layer interface. Further annealing in N₂ atmosphere (600°C < T < 1000°C) resulted in waveguide attenuation values lower than 1 dB/cm for λ = 0.633 μm.