Dose and Shape Modification Proximity Effect Correction for Forward-Scattering Range Scale Features in Electron Beam Lithography

For forward-scattering range scale features (α-scale features), the exposure contrast has too small a value to delineate the α-scale features using conventional dose modification proximity effect correction (PEC) in electron beam lithography. To delineate the α-scale features, the exposure contrast should be increased by shape modification. Therefore, we propose a dose-and-shape-modification PEC for α-scale features. The proposed PEC consists of two steps. The first step is the conventional dose modification PEC for the backscattering effect. The second step is the shape modification and dose compensation for the forward-scattering effect. A significant advantage of the proposed PEC is its low cost in terms of computation time, because shape modification and dose compensation for forward scattering are noniterative computations which do not consider the backscattering effect. Considering the exposure contrast, a separation distance larger than 2α between patterns is sufficient to delineate the α-scale features in the case of an equal lines-and-spaces (L&S) array. Experimental results are consistent with the simulation results, within a margin of error of approximately 5%. Using the proposed PEC, a 1.32α L&S array was delineated.