A methodology for the early exploration of design rules for multiple-patterning technologies

Double/Multiple-patterning (DP/MP) lithography in a multiple litho-etch steps process is a favorable solution for technology scaling to the 20nm node and below. Mask-assignment conflicts represent the biggest challenge for MP and limiting them through design rules is crucial for the adoption of MP technology. In this paper, we offer a methodology for the early evaluation and exploration of layout and MP rules intended for speeding up the rules-development cycle. Using a novel wiring-estimation method, we create layout estimates with fine-grained congestion prediction. MP-conflicts are then predicted using a machine-learning approach. In this work, we demonstrate the use of the method for double-patterning lithography in litho-etch-litho-etch process; the methodology is more general, however, and can be applied for other multiple-patterning technologies including tripe/multiple-patterning with multiple litho-etch steps, self-aligned double patterning (SADP), and directed self-assembly. Results of testing the methodology on standard-cell layouts show an 81% accuracy in DP-conflicts prediction. The methodology was then used to explore DP and layout rules and investigate their effects on DP-compatibility and layout area. The methodology allows for rules optimization; for example, pushing the minimum tip-to-side same-color spacing rule value from 1.7× to 1.5× the minimum side-to-side spacing design rule (i.e., from 110nm down to 90nm) would more than double the number of DP-compatible cells in the library.