Development and Evaluation of new MRC parameter for Aggressive Mask Optimization

As the design node gets smaller, using the aggressive mask optimization becomes indispensable emerging technology. However, during the aggressive optimization, we have frequently met problems that the optimized feature size gets smaller as Mask manufacturing Rule Checking (MRC) limitation. In this case, process window cannot improve more. Moreover, mask drawing error could be significant when the optimized main feature is as small as MRC limitation. As a solution for this problem, we have generally tried to develop the advanced mask manufacturing process. However, nowadays, it is truly not easy to improve the mask resolution. In this study, we found out the fact that the current MRC parameters are not good enough to reflect the mask patterning limitation. Thus, many small patterns have been eliminated by the MRC during the optimization, even though the patterns could be drawn well on the mask. In this paper, we suggest more effective MRC parameter; area based MRC. We introduce the evaluation result that represents the actual coverage of MRC. It proves that the area based MRC can reflect the mask process limitation much better than current MRC. Finally it is shown that the effect and utility of the area based MRC on the practical case by using inverse lithography technology (ILT).