Wafer-scale optical interconnect: from equipment, materials and processes over devices to the fabric

AI models continue to rapidly grow in size and complexity. The compute infrastructure required for training and inference is now increasingly limited by the scale-out and scale-up networks that connects CPUs, GPUs (XPUs), memory and storage together. As part of imec’s XTCO-Fabric program, we explore how optics can be used to eliminate there bottlenecks. The end-game will be the use of large-scale optical interposers where electrical connections on the XPU’s and HBM’s have been collapsed to their minimum, and connectivity is transparent with respect to link length. We explain how energy efficiency of optics can be reduced through the introduction of novel materials such as III-V, BTO and polymers on the Silicon Photonic platform. Advanced 3D assembly technologies such as wafer-to-wafer or die-to-wafer hybrid bonding is critical to achieve high bandwidth density (Terabit/s/mm) and reduce energy consumption. We explain how such technology is enabled through sophisticated tools and integration of carefully selected materials. Through its exploratory optical interconnect program, steered by system-level requirements from its XTCO program, imec is pathfinding solutions for these highly advanced systems. We call upon equipment manufacturers, material suppliers, foundries, test houses, fabless and system companies to work with us on this exciting journey. Finally, we explain how we will work even closer with Japan’s eco-system to bring this roadmap to reality with our brand new Hokkaido team. Stay tuned for more.