Control of temporal and spatial proximity effects in two-photon lithography

Le résumé fourni par la source

Two-photon lithography (TPL) enables the fabrication of high-resolution three-dimensional (3D) nanostructures, but its precision is often limited by proximity effects, leading to feature broadening and filamentary defects, both of which can depend on the timing between adjacent feature writing. This work experimentally explores the influence of process parameters, resist chemistry, and deposition techniques on temporal and filamentary proximity effects in TPL, in both lateral and vertical dimensions. We demonstrate that resist composition plays a crucial role in resolution, with TMPTA-based resists achieving superior fidelity. Exposure conditions, including outline and infill power, significantly affect temporal proximity effects as well. Simulations demonstrate that a competition of oxygen and initiator diffusion gives rise to complex interactions as their relative influence changes with spacing, timing, and laser power. Spin-coating is seen to improve uniformity but exacerbates proximity effects due to altered diffusion dynamics. Design modifications, such as strategic erosion of printed features and optimized scan paths, can further improve feature resolution. Notably, here we achieve hole sizes below 200 nm and gap separations under 150 nm in single-beam TPL without secondary processing–a resolution that, to our knowledge, surpasses prior reports for direct-written structures in infrared TPL without post-processing. These findings provide a pathway for fabricating high-density 3D nanostructures with improved fidelity, advancing next-generation photonic, biomedical, and metamaterial applications.

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