Region selective super-resolution imaging lithography for 3D via fabrication

Region-selective super-resolution imaging lithography method for three-dimensional (3D) via fabrication is proposed, based on self-aligned surface plasmon excitation induced by conformal vertical growth from a pre-patterned layer. In this approach, micron-scale prepatterns generated in a first lithography step act as natural physical boundaries that spatially confine plasmonic interference, enabling localized super-resolution imaging without requiring nanometer-scale masks or precise alignment in the secondary exposure. By engineering a conformal vertical metal-dielectric multilayer stack, high-wave-vector evanescent modes are supported under transverse-magnetic illumination, forming a self-aligned Ag/photoresist/Ag plasmonic cavity. Unlike conventional planar plasmonic lithography schemes, the proposed configuration maintains stable and uniform interference fields inside geometrically confined selective regions, effectively suppressing undesired exposure outside the target area. Finite-element method (FEM) and rigorous coupled-wave analysis (RCWA) simulations confirm uniform, high-contrast imaging in the predefined selective regions, achieving a minimum feature period of 50 nm (≈λ/17.4) at a 436 nm exposure wavelength. The method tolerates variations in pre-pattern period, duty ratio, dielectric spacer thickness, and incident angles, maintaining image contrast of 0.75-0.8 and normalized image log-slope of 1.31-1.72. This region-selective self-aligned plasmonic lithography strategy relaxes mask fabrication and alignment requirements and provides a scalable route toward high-aspect-ratio 3D nanofabrication.