Performance-Aware CMP Fill Pattern Optimization

CMP fills are inserted to make metal density uniform and hence reduce post-polish height variations. Classical methods to insert fills focus on metal density uniformity, but do not take into consideration or are unable to minimize the impact of fills on circuit performance. In this paper, we develop a fill insertion method that heuristically minimizes coupling capacitance increase due to fill. Our optimization methodology builds on fill insertion guidelines previously developed in, e.g., [12] and [1]. Experiments show that the proposed optimization methods can reduce fill impact on coupling capacitances by up to 85% for 30% pattern density and up to 65% for 60% pattern density cases.