Development of UV-Curable Resins Suitable for Reverse-Tone Lithography for Au Metamaterials Using a Print-and-Imprint Method

We developed a UV-curable resin (NL-SU1) suitable for screen printing with laser-drilled polyimide masks and reverse-tone nanoimprint lithography. The viscosity of the UV-curable resin composed of two bisphenol A-based monomers was adjusted to 11.0 Pa·s for the screen printing process. It was determined by photo-differential scanning calorimetry that photoinitiator Irgacure 369 was suitable for high methacrylate consumption in UV curing. The UV-curable resin after curing could be used as a top-coated resist layer on another imprinted resist layer because of its sufficient contrast in oxygen reactive ion etching and argon ion milling. We demonstrated a method for reverse-tone lithography in a print–and-imprint method to fabricate 20-nm-thick and 50-nm-linewide Au split-ring resonator arrays.