Detailed routing by sparse grid graph and minimum-area-captured path search.

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. We propose Dr. CU, an efficient and effective detailed router, to tackle the challenges. To handle a 3D 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 first place of ISPD 2018 Contest, our router improves the routing quality by up to 65% and on average 39%, according to the contest metric. At the same time, it achieves 80--93% memory reduction, and 2.5--15X speed-up.