This work presents a “half-etch” horizontal slot waveguide design based on SiN, where only the upper SiN layer is etched to form a strip that confines the mode laterally. The numerical modeling, fabrication, and characterization of passive waveguiding components are described. This novel slot waveguide structure was designed with on-chip light amplification in mind, for example with an Er-doped oxide spacer layer. Proof-of-concept racetrack resonators were fabricated and characterized, showing quality factors up to 50,000 at critical coupling and residual losses of 4 dB/cm at wavelengths away from the N-H bond absorption peak in SiN, demonstrating the high potential of these horizontal slot waveguides for use in active integrated photonics.

Integration of SiN films with Si photonics platforms is attractive for the 3D integration of multiple waveguide levels in optical routing circuits. This paper reports on the optical characterization of SiN films deposited by PVD and PECVD with the STMicroelectronics 300 mm Photonic R&D platform at CMOS-compatible temperatures. SiN deposition was engineered to reduce the propagation losses caused by 2nd harmonic vibrational absorption of NH bonds.