Viscosity range of UV-curable resins usable in print and imprint method for preparing sub-100-nm-wide resin patterns

The authors demonstrated a "print and imprint" method comprising screen printing and ultraviolet (UV) nanoimprinting for preparing sub-100-nm-wide cured resin patterns. In the screen printing, UV-curable resins with viscosities in the range of 6.26-266 Pa s were deposited as droplet shapes on Si surfaces using a polyimide through-hole membrane mask with a hole diameter of 10 μm and a hole pitch of 45 μm. The low-volatile high-viscosity resin of 12.8 Pa s had an advantage of maintaining the droplet shapes 3 h after deposition. The spherical segment-shaped droplets showed an average diameter of 18.9 μm and height of 1.63 μm. The average volume was approximately 230 μm³ (0.230 pl) which was close to that dispensed by ink-jet printing. The droplet resin on a modified Si surface was filled into recesses of a fluorinated silica mold, and the molded resin was cured by UV nanoimprinting. Although the displacement of resin droplets was periodically uniform on substrate surfaces, the thicknesses of residual layers were almost identical to 0.12 μm in 45, 60, 80, and 100-nm-wide line and space patterns in the range of 1 mm length. The authors confirmed that the resin droplets with a viscosity of 12.8 Pa s could be transformed into imprinted resin patterns with a residual layer thickness of 0.12 μm without obvious nonfill defects.