13.5 Subtractive Photonic Waveguide-Coupled Photodetectors in 180nm Bulk CMOS

The integration of electronics and photonics into a single silicon CMOS process can serve wide-ranging applications, e.g. complex imaging and projection photonic systems, on-chip optical interconnects, or self-correcting photonic circuits. Current silicon photonics processes built using silicon on insulator (SOI) are either optimized for the photonic devices with no active electronic circuitry available [1] or are relatively expensive [2]. Bulk CMOS processes can be modified to accommodate photonics [7], but currently no commercial foundry offers this option to customers, and an ideal integration method would enable photonics on any bulk CMOS node. Previous attempts to integrate photonics into unmodified bulk CMOS processes, using the polysilicon gate layer for waveguiding, have resulted in large waveguide losses [3] [4].