DCO-3D: Differentiable Congestion Optimization in 3D ICs

State-of-the-art 3D IC flows fail to consider 3D congestion during earlier stages, leading to excessive use of end-of-flow ECO resources for routability correction that severely degrades full-chip Power, Performance, and Area metrics. We present DCO-3D, a Machine Learning-based routability-aware 3D PD flow that performs early post-route congestion prediction using Siamese Networks and resolves the predicted hotspots using a fully differentiable 3D cell spreading with Graph Neural Network. On 6 industrial designs in a commercial 3nm node, DCO-3D improves Pin-3D, the known best Pin-3D flow, by up to 47.2% in overflow, 86.2% in TNS and 5.1% in power at signoff.