Enhancing imaging structure compatibility in surface plasmonic lithography via particle swarm optimization.

Plasmonic lithography, which utilizes evanescent near-field imaging that contains high-frequency information, can overcome the diffraction limit of conventional lithography and has emerged as a strong candidate for next-generation integrated circuit (IC) manufacturing. Previous research has primarily focused on improving the resolution limits of plasmonic lithography, while compatibility studies have been largely overlooked. Imaging structure compatibility with mask patterns is an important consideration in lithographic processes for IC fabrication, and plasmonic lithography is particularly sensitive to the pitch of mask patterns-since the pitch determines whether the spatial frequency of the mask's diffraction orders matches the wavevector of surface plasmon polaritons (SPPs), enabling beyond-diffraction imaging. This study focuses on plasmonic imaging lithography structures, establishing a method and workflow for optimizing imaging structure compatibility using a plasmonic lithography optical imaging model based on the rigorous coupled-wave analysis (RCWA) algorithm and particle swarm optimization (PSO). By optimizing imaging structure compatibility, this approach achieves compatibility with various line/space mask patterns from the 7 nm to 28 nm technology nodes. The results are further validated by COMSOL models based on the finite element method (FEM) and coherent transfer function (CTF) analysis. The proposed optimization methodology and workflow establish a solid foundation for enhancing plasmonic lithography compatibility, advancing its path toward industrial application.