CSCO: A Backside-PDN-Aware Clock-Signal Co-Optimization Framework for Improved PPA

2026-07-15

AI Summary

This work addresses the challenges in backside power delivery networks (BSPDNs), where limited backside routing resources must be judiciously shared between clock and signal networks, and the absence of front-side power/ground shielding severely degrades signal integrity. To tackle these issues, the paper proposes CSCO, a novel framework that enables, for the first time, co-optimization of clock and signal networks across frontside and backside layers. Leveraging a data-driven, efficient search strategy, CSCO identifies critical nets for backside routing, achieving an optimal trade-off among IR drop, congestion, and power-performance-area (PPA) metrics. Notably, it mitigates coupling noise and crosstalk effectively without incurring additional shielding overhead. Experimental results demonstrate that CSCO significantly improves worst negative slack (WNS), total negative slack (TNS), operating frequency, and overall signal integrity robustness.

Abstract

Backside power delivery networks (BSPDN) have emerged as a promising technology for advanced logic nodes to address IR-drop and PPA challenges. While BSPDN introduces additional routing resources on the backside, these resources are limited and must be carefully partitioned between clock and signal nets, creating a critical resource allocation tradeoff. Prior work either moves only the clock network or assumes a fixed clock tree and optimizes only signal nets, failing to explore the tradeoff space of backside resource allocation. Moreover, lacking frontside power-ground shielding, BSPDN introduces severe signal integrity (SI) degradation. We propose CSCO, a data-driven BSPDN-aware co-optimization framework that jointly allocates limited backside resources between clock and signal nets across frontside/backside layers. CSCO employs efficient search strategies to identify critical nets for backside routing without repeated evaluation, navigating the clock-signal allocation tradeoff to balance IR-drop, routing congestion, and PPA. The framework also leverages backside routing to mitigate coupling noise and crosstalk-induced SI issues. Experiments demonstrate improved WNS/TNS, frequency, and SI robustness without additional shielding overhead.

Problem

• Backside Power Delivery Network
• Clock-Signal Co-Optimization
• Resource Allocation
• Signal Integrity
• IR-drop

Innovation

• Backside Power Delivery Network
• Clock-Signal Co-Optimization
• Signal Integrity
• Resource Allocation
• PPA Optimization