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

Abstract

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.

Selecting adhesive molecular layers with matched surface free energy and chemisorption for shape-fixed UV-cured thin films fabricated by laser-drilled screen printing and UV nanoimprinting

“…The average height was determined by an oblique scan of cured droplets using a surface profiler (Kosaka Laboratory Surfcorder ET4000A) in the same manner as reported previously. 24) The average volume was calculated under the assumption that cured droplets had a spherical segment. 24) 2.4.…”

“…24) The average volume was calculated under the assumption that cured droplets had a spherical segment. 24) 2.4. UV nanoimprinting with a modified flat mold A custom-made nanoimprinter was assembled by Mino Group, Asahi Kasei Engineering, and Koken.…”

“…22) For UV-curable composite liquids with viscosities of higher than 1 Pa•s, laser-drilled screen printing and UV nanoimprinting have been proposed by the authors. [23][24][25][26] UV-curable composite liquids suitable for UV-NIL must have the following characteristics: the ability to handle quantitatively, low volatility, filling performance, low curing shrinkage, and excellent demolding. Because inkjet printing and laser-drilled screen printing quantitatively enable the placement of UVcurable droplets on a predetermined region of the substrate surface, the use of a mold having a mesa terrace with an area larger than the region of printed droplets prevents the formation of resin burrs that lead to unshaped defects of substrate surfaces after etching.…”

Micro-print and nano-imprint methods combining laser-drilled screen printing and ultraviolet nanoimprint lithography: a review

“…Screen printing with a polyimide mask with a hole diameter of 10 μm and a hole pitch of 45 μm can place droplets with a viscosity of more than 6 Pa s on silicon wafer surfaces. 25) To lower the viscosity for laser-drilled screen printing with polyimide through-hole masks, the surface modification of the mask surface was investigated. Because UV-curable liquids for UV nanoimprinting are generally classified into hydrocarbon compounds, polyimide mask surfaces were modified with an oleophobic surface modifier of tridecafluoro-1,1,2,2-tetrahydrooctyltrimethoxysilane (FAS13).…”

High-Intensity Laser Irradiation Inducing Au Nanoparticles in Viscous Glycerin

“…We developed laser-drilled screen printing techniques to place droplets of high-viscosity photo-curable liquids on substrate surfaces for ultraviolet nanoimprint lithography. High-viscosity liquids in the viscosity range of approximately 1,000 -300,000 mPa s can be screen-printed as droplets with certain desired volumes of sub-pico-liters site-selectively on a substrate surface [3,4] . The characteristic is to use laser-drilled polyimide masks.…”