Silicon Oxynitride can be deposited by PECVD, using silane, nitrous oxide and ammonia source gases. Deposition temperature is normally around 350 degrees C, pressure between 750mTorr and 1 Torr. It is possible to deposit anything between silicon dioxide and silicon nitride by adjusting the proportion of gases. Naturally, the refractive index will reflect the composition. It is possible to control the refractive index very accurately, which is good news for anyone making waveguides using this material. Drop me an email (martin.walker@oxinst.co.uk) if you need any details on equipment for this process. Martin Walker Mr. Martin Walker, Senior Applications Engineer Oxford Instruments Plasma Technology North End, Yatton, Bristol, BS49 4AP, UK Tel. +44 1934 837031 Fax. +44 1934 837001 Original message