Systematic λ/21 resolution achieved in nanofabrication by two-photon-absorption induced polymerization

Photopolymerization, based on two-photon absorption in resins, has been recognized as one of the enabling technologies to fabricate 3D micro/nanostructures with a sub-diffraction-limit resolution. This work focuses on improving the spatial resolution using femtosecond laser, lambda = 780nm, with a systematic nanofabrication process which we developed. We discuss the factors influencing the spatial resolution, including the laser intensity, the exposure time, and the scanning speed by fabricating polymerized-voxels, nano-lines, and suspended nano-fibers in a photoresist based on a methyl-methacrylate monomer. We show that a resolution of similar to 36nm, corresponding to similar to lambda/21, is achieved. Stable 3D microstructures can be fabricated by using our custom made set up.