[19p-S224-1~17] 7.3 Micro/Nano patterning and fabrication

[19p-S224-11] Dependence of film thickness on surface elasticity observed for
sub-100 nm-thick UV-cured resin films by atomic force microscopy

〇(M1)HARUNA YANO¹, SHOICHI KUBO², MASARU NAKAGAWA¹, XIAOBIN RIANG³, SO FUJINAMI⁴, KEN NAKAJIMA³ (1.Tohoku Univ., 2.NIMS, 3.Tokyo Tech., 4.RIKEN)

Keywords:surface elasticity,UV-cured resin,atomic force microscope

We investigated the surface elasticity of UV-cured resin films. Liquid UV-curable resin was spincoated on an Au deposited substrate. UV nanoimprinting was carried out with a light intensity of 100 mW cm^-2 monitored at 365 nm for 20 s under an HFC-245fa atmosphere. Young’s modulus was evaluated by atomic force microscopy (AFM). The mean values of the Young’s moduli in UV-cured resin films with a thickness of 117 nm, 50 nm, and 31 nm were 1.10 GPa, 0.81 GPa, and 0.44 GPa, respectively. The Young’s moduli decreased with a decrease of film thickness. We discuss what occurred in the UV-cured resin films. It was thought that monomers could diffuse in three-dimensional directions in thick film states, whereas the monomer diffusion would be limited to two-dimensional directions in thin film states.
We considered that the decrease of Young’s moduli in the thin UV-cured film was attributed to the inhibition of the monomer diffusion in radical photopolymerization.