Low-Loss, Multi-Reticle-Stitched SiN Waveguides for 300 mm Wafer-Level Optical Interconnects

With the rapid development of artificial intelligence (AI) and machine learning (ML) applications, wafer-level optical I/O is becoming increasingly attractive for massive and efficient data interconnects in future wafer-scale multi-processor-units (multi-XPU) compute clusters with unparalleled data bandwidth, energy efficiency, and low latency. In this paper, we present a 300 mm sized wafer reticle-stitched low-pressure chemical vapor deposition (LPCVD) silicon nitride (SiN) waveguide technology and demonstrate a multi-reticle-stitched ~56 cm long waveguides across 20 reticles with propagation loss of 0.13~0.15 dB/cm at 1310 nm wavelength, and <0.001~0.002 dB SiN waveguide stitch loss, which is because of <5 nm high-precision reticle lithography offset. These advantageous features of low-loss reticle-stitched SiN waveguides have the potential to significantly enhance future optically interconnected wafer-scale multi-chip compute systems.