Area-I/O flip-chip routing for chip-package co-design

The area-I/O flip-chip package provides a high chip-density solution to the demand of more I/Opsilas in VLSI designs; it can achieve smaller package size, shorter wirelength, and better signal and power integrity. In this paper, we introduce the routing problem for chip and package co-design and present the first work in the literature to handle the multiple Re-Distribution Layer (RDL) routing problem for flip-chip designs, considering pin and layer assignment, total wirelength minimization, and chip-package co-design. Our router adopts a two-stage technique of global routing followed by RDL routing. The global routing assigns each block port to a unique bump pad via an I/O pad and decides the RDL routing among I/O pads and bump pads. Based on the minimum-cost maximum-flow algorithm, we can guarantee 100% RDL routing completion after the assignment and the optimal solution with the minimum wirelength. The RDL routing efficiently distributes the routing points between two adjacent bump pads and then generates a 100% routable sequence to complete the routing. Experimental results based on 10 industry designs demonstrate that our router can achieve 100% routability and the optimal routing wirelength under reasonable CPU times, while related works cannot.