Self-Aligned Double-Patterning Aware Legalization

Abstract

Double patterning is a widely used technique for sub-22nm. Among various double patterning techniques, Self-Aligned Double Patterning (SADP) is a promising technique for good mask overlay control. Based on SADP, a new set of standard cells (T-cells) are developed using thicker metal wires for stronger drive strength. By applying this kind of gates on critical paths, it helps to improve the design performance. However, a mixed design with T-cells and normal cells (N-cells) requires that T-cells are placed on circuit rows with thicker metal, and the normal cells are on the normal circuit rows. Therefore, a placer is needed to adjust the cells to the matched circuit rows. In this paper, a two-stage min-cost max-flow based legalization flow is presented to adjust N/T gate locations for a legal placement. The experimental results demonstrate the effectiveness and efficiency of our approach.