[15p-512-1~9] Progress and outlook of nanoimprint technology

[15p-512-2] Approach to single-digit-nanometer patterning in UV nanoimprinting by surface molecular science

Shunya Ito¹, 〇Masaru Nakagawa¹ (1.IMRAM, Tohoku Univ.)

Keywords:UV nanoimprinting, single-digit-nanometer patterning, surface molecular science

We introduced an approach to single-digit-nanometer patterning by UV nanoimprinting from a standpoint of surface molecular science. Although several studies have reported sub-15 nm resist patterning, detailed chemical structures of monomers and antisticking moelcular surfaces suitable for UV nanoimprinting to fabricate single-digit-nanometer features still remain scientifically unclear. We recently reported a specific resin filling behavior into around 20-nm-diameter holes in UV nanoimprinting using molds with an antisticking carbon layer. We clarified that hydroxy-containing monomers tended to fill easily into around 20-nm-diameter holes. We concieved that monomer viscosity in nano-space was higher than than in bulk state. Therefore, we started to study nanometer-resolved fluidity of diacrylate monomers confied between unmodified and modified silica surfaces by surface forces and resonance shear measurements. The viscosity of monomers remarkably increased under the confinement. Fluorine-containing monolayers suppressed an increase in viscosity closer to the interface. In contrast, the long fluoroalkyl-containing monolayer caused an oleophilic monomer to be squeezed out between the surfaces. As the viscosity of monomer became high, the increase in monomer viscosity near the surface was suppressed. Using recently fabricated silica molds with 7-nm-diameter holes, we demonstrated UV nanoimprinting at 7 nm. These results suggested that increased monomer viscosity in nano-space will infuluence on not only resin filling into mold recesses, but also horizontal movement of a mold for alignment, photopolymerization of UV-curable resins, and pull-out defects due to abundant uncured monomers. We conclude that the approach from a standpoint of surface molecular science will be an imprtant key for single-sigit-nanometer patterning by UV nanoimprinting.