Stitching-aware in-design DPT auto fixing for sub-20nm logic devices

As the technology continues to shrink below 20nm, Double Patterning Technology (DPT) becomes one of the mandatory solutions for routing metal layers. From the view point of Place and Route (P&R), the major concerns are how to prevent DPT odd-cycles automatically without sacrificing chip area. Even though the leading-edge P&R tools have advanced algorithms to prevent DPT odd-cycles, it is very hard to prevent the localized DPT odd-cycles, especially in Engineering Change Order (ECO) routing. In the last several years, we developed In-design DPT Auto Fixing method in order to reduce localized DPT odd-cycles significantly during ECO and could achieve remarkable design Turn-Around Times (TATs). But subsequently, as the design complexity continued increasing and chip size continued decreasing, we needed a new In-design DPT Auto Fixing approach to improve the auto. fixing rate. In this paper, we present the Stitching-Aware In-design DPT Auto Fixing method for better fixing rates and smaller chip design. The previous In-design DPT Auto Fixing method detected all DPT odd-cycles and tried to remove oddcycles by increasing the adjacent space. As the metal congestions increase in the newer technology nodes, the older Auto Fixing method has limitations to increase the adjacent space between routing metals. Consequently, the auto fixing rate of older method gets worse with the introduction of the smaller design rules. With DPT stitching enablement at In-design DRC checking procedure, the new Stitching-Aware DPT Auto Fixing method detects the most critical odd-cycles and revolve the odd-cycles automatically. The accuracy of new flow ensures better usage of space in the congested areas, and helps design more smaller chips. By applying the Stitching-Aware DPT Auto Fixing method to sub-20nm logic devices, we can confirm that the auto fixing rate is improved by ~2X compared with auto fixing without stitching. Additionally, by developing the better heuristic algorithm and flow for DPT stitching, we can get DPT compliant layout with the acceptable design TATs.