Hierarchical DPT Mask Planning For Contact Layer

This paper investigates contact layer mask planning for DPT, and presents results on two new problems due to hierarchical processing. LELE/LFLE based double patterning (DPT) with ArF water-based immersion systems has emerged as a strong candidate to first extend lithography to 32nm and below. Mask planning for DPT consists of conflict visualization when design is not manufacturable with DPT and mask assignment either when it is or despite it is not. Concurrent with the advancements in double patterning process, there has been active research addressing the problem of mask planning. As geometries across the chip can potentially involve in the same conflict, DPT decomposition has been recognized as unbounded. This paper will show that the unbounded nature of a potential conflict drawing in geometries from across the chip, however, poses little obstacle to efficient conflict visualization or mask assignment.