Source optimization for less aggressive optical proximity correction in 0.55 NA logic single patterning

초록

Logic metal layers, consisting of randomly arranged metal lines with various pitches, are intended to be printed by EUV single exposure. However, when such layers are exposed using a simple source, differences in pattern density and shape cause significant critical dimension (CD) variation, preventing the printed features from matching the target design. Moreover, the complexity of optical proximity correction (OPC) increases with pattern diversity and reduced feature size, resulting in higher computational cost and more challenging mask fabrication. In this study, we investigate the potential of pixelated source optimization to achieve high-fidelity patterning of logic metal layers without any use of OPC or bias. The optimized source is evaluated for different absorbers under 0.55 NA conditions. By comparing optimal source shapes for each absorber, we demonstrate that pixelated sources can reproduce the intended patterns while achieving high normalized image log slope (NILS) and a wide process window. This approach offers a pathway toward less aggressive OPC and improved manufacturability for future logic single patterning. © 2025 SPIE. All rights reserved.

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