Stable transfer technique of anti-reflection
structure using high hardness and anti-fouling
UV curable resin
Junya Kawauchi1, Shin Hiwasa2, Jun Taniguchi1
Department of Applied Electronics1, Tokyo University of Science, 6-3-1 Niijyuku,Katsusika, Tokyo 125-8585, Japan
Autex Co., Ltd.2, 16-5 Tomihisa-chou, Shinjuku-ku, Tokyo 162-0067, Japan
E-mail: junt@te.noda.tus.ac.jp

1. Introduction
A moth-eye structure, which is one of the anti-reflection structures (ARS), is manufactured
by processing an oxygen ion shower on a glassy carbon (here after “GC”). Fabricated motheye structure on GC surface can use as an Ultraviolet nanoimprint lithography (UV-NIL)
mold. However, this moth-eye structured mold is very fragile for high hardness UV-curable
resin, so repetition UV-NIL is difficult. Typically, this mold was damaged around from fiveto ten times repetitions. To avoid this problem, we tried to use a replica mold, which madefrom moth-eye structured GC mold, for repetition UV-NIL process. A replica mold material
was PAK-01-CL (TOYOGOSEI Co., Ltd., here after “PAK-mold”) and transfer material wasnewly developed resin [1], which has high hardness and anti-fouling effect.
2. Fabrication process
Fig. 1 shows a fabrication process of moth-eye structure of newly developed resin from PAKmold. A newly developed resin was dropped onto a PAK-mold (Fig. 1(a)), and UV curing
was carried out with 80 oC heating and 1.08 kPa pressure. The UV dose was 50 J/cm2 (Fig.
1(b)). After curing, replica mold was released (Fig. 1(c)). After releasing, transferred pattern
was baked to obtain release property (Fig. 1(d)). We examined how many times the PAKmold can transfer to newly developed resin. The transfer process was from Fig. 1(a) toFig .1(c). In this experiment, every reflections of transferred moth-eye structures weremeasured and when the reflection was over 1.0% at 550nm wavelength, repetition UV-NIL
was quit.
3. ResultFig. 2 shows the reflectivity of moth-eye structures with newly developed resin. It shows thereflectance was increased by increasing of repetition times. In this experiment, UV-NIL wasquit at 63 repetition times. Fig. 3 shows the SEM images of moth-eye structures at 1st (Fig.
3(a)) and 60th (Fig. 3(b)) by using newly developed resin. The heights of the moth-eye
structure of the 1st and 60th were 228 nm, and 187 nm. These results show the reflectivity wasincreased by decreasing of moth-eye structure height.
4. Conclusion
Using replica mold (PAK-mold), repetition transfers is possible for newly developed resinwith moth-eye structure. The replicated high hardness and anti-fouling moth-eye structure has
low reflectivity, high hardness and hydrophobic properties and these properties are very
useful for practical ARS film [1]. Thus, stable transfer technique using replica mold is very
important.
Reference:[1] Hikari Eto, Shin Hiwasa, Jun Taniguchi, “Tough and antifouling antireflection structuresmade by partial-filling ultraviolet nanoimprint lithography” Microelectronic Engineering 197(2018) 33–38

Figure 1. The fabrication process of moth-eye structure of newly developed resin from PAK-mold.

Figure 2. The reflectivity of moth-eye structure made of newly developed resin.

(a)(b)
Figure 3. The SEM images of height of moth-eye structure made of newly developed resin.
(a) 1st transfer sample, (b) 60th transfer sample.