Double patterning for 20nm and beyond: design rules aware splitting

Abstract

Double patterning presents itself as one of the best candidates for pushing the limits of ArF lithography to 20nm technology node and below. It has the advantage of theoretically decreasing the minimum resolvable pitch by a factor of two, or the improvement of the process window by relaxing the lithographic conditions. Double patterning though has its own complexities. Not only sophisticated algorithms are required to simply split the design into two exposures, but these two exposures have to comply with the design manual rules. The number and the complexity of these rules tend to increase for more compact designs in terms of minimum CD and layout topology which in turns increase the coding burden on engineers to let the splitting code be aware of such numerous rules. In this context, we are proposing a new double patterning flow. It will be shown how the splitting can be done while taking into account numerous design rules. And finally, rules prioritization will be discussed in order to avoid conflicts between them.