Simultaneous EUV Flare Variation Minimization and CMP Control by Coupling-Aware Dummification

Abstract

Extreme ultraviolet (EUV) flare and post-chemical mechanical polishing (CMP) metal thickness are two main manufacturability concerns that introduce critical dimension distortions in nanometer process technology. Dummification, the addition of dummy patterns, is an effective technique to address the two concerns. However, while the two dummification objectives are competing in nature, existing works only tackle them separately, leading to problem-prone solutions because optimizing one would unavoidably deteriorate the other. This paper presents a new and effective method that simultaneously considers both concerns during dummification. Manufacturing sensitivity toward the two concerns are taken into account with a user-specified evaluation model adaptive to the adopted technology. Given the point spread function of a system and the evaluation model, our proposed two-stage method is able to find at the first stage an initial dummy assignment with better EUV flare uniformity than that obtained by a previous quasi-inverse method. With the initial assignment as the starting point, the gradient-guided optimization is then adopted to iteratively refine dummy distribution toward improved CMP quality. Experimental results on industrial test cases show the effectiveness of our method.