Beyond Backside Power: Backside Signal Routing as Technology Booster for Standard Cell Scaling

Advances in process technology enabling backside metals and contacts offer new Design-Technology Co-Optimization (DTCO) opportunities to further enhance power, performance, and area gains (PPA) in sub-3nm nodes. This work exploits backside contact technology within standard cells to extend both signal and clock routing to backside metal layers, enabling standard-cell height reduction options. We design electrically equivalent standard cells with multiple layout variants based on front versus backside pin access, achieving a 2-M0-track height reduction in 3nm Gate-All-Around Field-Effect Transistor (GAAFET) technology. Experimental evaluation across representative industrial benchmarks — including high-performance CPUs, GPUs, and general-purpose SoCs demonstrates significant benefits. Cell height reduction delivers up to 35% area savings and 10–15% total power reduction for GPU and GP-SoC designs. For high-performance CPUs, maximum performance improves by 15% at iso-power compared to backside-power using buried power rails (BSBPR). Incorporating backside signal routing with cell height reduction also reduces worst-case IR-drop by 32% relative to BSBPR. These results show that backside clock and signal routing represent the next phase of technology innovation beyond backside power delivery, enabling continued standard-cell scaling, improved intra- and inter-cell routability, and generational PPA gains while maintaining similar core transistor geometries in sub-3nm technologies.