Model based hybrid proximity effect correction scheme combining dose modulation and shape adjustments

Abstract

The authors present a general approach to combine model-based dose modulations and shape modifications into a hybrid proximity effects correction (PEC) scheme for electron beam lithography. The authors simplify this scheme significantly by using an appropriate dose correction strategy. This allows us to use an existing optical proximity correction tool for the shape adjustments. This hybrid PEC scheme is demonstrated by computing corrections for simple test patterns as well as a more complex pattern. The model used corresponds to an electron multibeam tool with an acceleration voltage of 50 kV. It predicts resist contours from a written dose distribution. The authors evaluate the quality of the results both for nominal process conditions and in the presence of process variations. The results are compared against the corresponding results for a correction using only dose modulation. The authors also use the hybrid scheme to compensate intentional overexposure by shape adjustments and include these results in the comparison so that the impact of overexposure on robustness against process variations can be determined.