Effect of precursors on propagation loss for plasma-enhanced chemical vapor deposition of SiNx:H waveguides

This work investigates the role of precursor gas chemistry, SiH4/NH3/N-2, on hydrogen incorporation into PECVD H: SiNx for optical applications. The largest reduction in of N-H bond density is shown to respond from SiH4 flow, indicating that all precursor gases must be optimized for low loss waveguides. A linear correlation of N-H bond density with propagation losses in SiNx waveguides is observed, allowing for a propagation loss to be estimated by N-H bond density without waveguide fabrication. With proper optimization of process parameters, we are able to obtain propagation losses as low as -1.6 dB/cm at 1550 nm without a thermal anneal. (C)2016 Optical Society of America