Redundant via insertion with cut optimization for self-aligned double patterning

Abstract

Line-end cuts are employed to enable 1D gridded designs in self-aligned double patterning (SADP) process. Due to the minimum spacing constraints between adjacent cuts, cut optimization is important component. However, it brings a new challenge to redundant via (RV) insertion. As the cuts for RVs are not taken into account during line-end cut optimization, inserting some RVs may cause coloring conflicts or design rule violations. In this paper, we address integrated RV insertion and cut optimization problem. Given a via layout, the proposed approach optimizes the cuts in upper and Lower metal layers, which are connected through a via, while RV candidate positions are considered. Only the RV candidates that do not incur coloring conflicts nor design rule violations are chosen. Our experiments indicate that only 55.3% of vias receive RVs when cut optimization and RV insertion are performed separately; corresponding number increases to 86.4% when our approach is applied.