Three-Dimensional Nanopatterning Using Extreme Ultraviolet Colloidal Talbot Lithography.

While extreme ultraviolet (EUV) lithography has enabled the continued scaling toward high-resolution features, existing processes are limited to patterning of planar two-dimensional (2D) structures. This work demonstrates EUV colloidal Talbot lithography (CTL) for the patterning of 3D nanostructures with 25 nm minimum feature sizes. In this approach, a monolayer of self-assembled nanospheres is utilized as a binary mask and illuminated using a tabletop high-harmonic generation (HHG) EUV source to form a volumetric intensity pattern for proximity-field printing. The interference pattern formation is investigated using finite difference time domain (FDTD) simulations and maintains an adequate fringe contrast within the volume. Experimental results demonstrate the fabrication of 2D nanostructures with tunable unit-cell geometry and 3D nanostructures down to 25 nm using a single exposure. This cost-effective approach enables single-exposure 3D EUV lithography with low hardware requirements and has broad applications in nanophotonics, quantum devices, and advanced materials.