3D resist profile evolution in high-NA EUV lithography for random logic vias: simulation and experiment insights

Abstract

High numerical aperture (high-NA) extreme ultraviolet lithography (EUVL) introduces challenges in resist profile control and pattern fidelity, particularly for advanced logic via configurations. We evaluate resist profile evolution and local critical dimension uniformity (LCDU) across different via configurations under 0.55 NA extreme ultraviolet exposure. We integrate aerial image modelling with a physics-based resist development framework and benchmark simulated profiles against wafer inspection data, including after-development and after-etch stages. At best focus, all tested via configurations (isolated, doublet, and diagonal triplet) exhibit LCDU below 2 nm, whereas positive defocus causes significant LCDU degradation in the dense diagonal triplet pattern, indicating strong layout-dependent focus sensitivity. Importantly, conventional top-down critical dimension (CD) scanning electron microscopy metrology is found to overestimate the lithographic process window by failing to capture incomplete resist openings and bottom CD loss observable in cross-section. These results underscore the need for detailed three-dimensional resist profile analysis and integrated lithography–etch co-optimization to ensure robust process development at high-NA EUVL.