Structural and optical properties of silicon oxynitride on silicon planar waveguides

Planar optical waveguides on thermally oxidized Si(111) substrates have been made with rf magnetron sputtering deposition from a SiO(2) target in a N(2) 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 SiO(2) and silicon oxynitride, with an extended intermixed region at the thermal SiO(2) buffer layer interface. Further annealing in N(2) atmosphere (600 degrees C < T < 1000 degrees C) resulted in waveguide attenuation values lower than 1 dB/cm for lambda = 0.633 microm.