Is your layout-density verification exact?A fast exact deep submicrometer density calculation algorithm

As the device shapes keep shrinking, the designs are more sensitive to manufacturing processes. In order to improve performance predictability and yield, mask-layout uniformity/evenness is highly desired, and it is usually measured by the feature densities within defined feasible ranges determined by the manufacturing-process design rules. To address the density-control problem, one fundamental problem is how to calculate density accurately and efficiently. In this paper, we propose a fast exact algorithm to identify the maximum/minimum density for a given layout. Compared with the existing exact algorithms, our algorithm reduces the running time from days/long hours to a few minutes/seconds. Moreover, it is even faster than the existing approximate algorithms in the literature.