Overlay-aware detailed routing for self-aligned double patterning lithography using the cut process

Abstract

Self-aligned double patterning (SADP) is one of the most promising techniques for sub-20nm technology. Spacer-is-dielectric SADP using a cut process is getting popular because of its higher design flexibility; for example, it can decompose odd cycles without the need of inserting any stitch. This paper presents the first work that applies the cut process for decomposing odd cycles during routing. For SADP, further, overlay control is a critical issue for yield improvement; while published routers can handle only partial overlay scenarios, our work identifies all the scenarios that induce overlays and proposes a novel constraint graph to model all overlays. With the developed techniques, our router can achieve high-quality routing results with significantly fewer overlays (and thus better yields). Compared with three state-of-the-art studies, our algorithm can achieve the best quality and efficiency, with zero cut conflicts, smallest overlay length, highest routability, and fastest running time.