Photonic integrated circuits on Si have been attracting much attention and are being intensively investigated. On a Si photonic chip, in addition to the monolithic Si and Ge photonic devices, InP-based active devices can be integrated heterogeneously by utilizing direct-bonding technology. To connect these functional devices, we have proposed back-end photonic wiring using silicon oxynitride (SiOxNy) -based waveguides. In this paper, we report recent progress in our back-end photonics integration technology. First, back-end SiOx waveguide integration with InP-based membrane active devices will be presented. Then, our technology for the low-loss SiOxNy deposition at low temperature will be presented, which is applied to a SiN waveguide for compact arrayed-waveguide-grating (AWG) filter and Ge integration. These technologies have attributes for future highly integrated photonic circuits on Si.