Dr. CU: Detailed Routing by Sparse Grid Graph and Minimum-Area-Captured Path Search

Abstract

Different from global routing, detailed routing takes care of many detailed design rules and is performed on a significantly larger routing grid graph. In advanced technology nodes, it becomes the most complicated and time-consuming stage in the very large-scale integration physical design flow. We propose Dr. CU, an efficient and effective detailed router, to tackle the challenges. To handle a 3-D detailed routing grid graph of enormous size, a set of two-level sparse data structures is designed for runtime and memory efficiency. For handling the minimum-area constraint, an optimal correct-by-construction path search algorithm is proposed. Besides, an efficient bulk synchronous parallel scheme is adopted to further reduce the runtime usage. Compared with the other state-of-the-art academic detailed routers, Dr. CU reduces the number of design rule violations by one or two orders of magnitude. At the same time, it uses shorter wire length, fewer vias, and significantly less runtime. The source code of Dr. CU is available at https://github.com/cuhk-eda/dr-cu.