Power Delivery Network (PDN) is one of the most challenging topics in modern VLSI design. Due to aggressive technology node scaling, resistance of back-end-of-line (BEOL) layers increases dramatically in sub-10nm VLSI, causing high supply voltage (IR) drop. To solve this problem, pre-placed or post-placed power staples are inserted in pin-access layers to connect adjacent power rails and reduce PDN resistance, at the cost of reduced routing flexibility, or reduced power staple insertion opportunity. In this work, we propose dynamic programming-based single-row and double-row detailed placement optimizations to maximize the power staple insertion in a post-placement flow. We further propose metaheuristics to improve the quality of result. Compared to the traditional post-placement flow, we achieve up to 13.2% (10mV) reduction in IR drop, with almost no WNS degradation.
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