Metallic Color Filter Fabrication using Photo-Curable Polymer Stacking

Abstract

Nanoimprint lithography (NIL) can be used as a tool for three-dimensional nanoscale fabrication. In particular, complex metal pattern structures in polymer material are demanded as plasmonic effect devices and metamaterials. To fabricate of metallic color filter, we used silver ink and liquid-transfer imprint lithography (LTIL) techniques. Metallic color filter was composed of stacking of nanoscale silver disc patterns and polymer layers, thus, controlling of polymer layer thickness is necessary. To control of thickness of polymer layer, we used spin-coating of UV-curable polymer and LTIL process. To obtain silver disc pattern, we used silver ink, Ultraviolet NIL technique and LTIL process. As a result, ten stacking layers with 1000 nm layer thickness was obtained and red color was observed. The obtained colors are generated from plasmon phenomenon. This process is very useful to make stacking structure without vacuum environment. Keyword: liquid-transfer imprint lithography, nanoimprint lithography, UV-curable resin, metallic color filter, silver ink IntroductionThere is a growing demand for a nanoscale metal disc stacking technique to fabricate next-generation devices such as plasmonic devices, metamaterials, and memory devices [1][2][3]. In particular, complex three-dimensional (3D) structure is difficult to fabricate. Stacking these metal structures in transparent resin and insulators is usually achieved with lithographic patterning, metal deposition, and a lift-off process: the desired pattern of resin is first fabricated on the substrate, the metal layer is then deposited by thermal evaporation or sputter coating, and the resin is removed by chemical dissolution. Resin patterning is typically performed using electron beam lithography (EBL) or nanoimprint lithography (NIL) [4], but for further efficient fabrication, NIL can also be used to transfer both the metal patterns and the intermediate resin layer. However, it is difficult to control the thickness of the intermediate resin layer with this technique. To improve this issue, we have developed efficient process by using liquid transfer imprint lithography (LTIL)

Durability Evaluation of Antireflection Structure Replica Mold using High Hardness and Antifouling UV-curable Resin

“…The replica mold is made by UVcurable resin for experiment. To prepare the replica mold, we first coated the master mold with a 30-nm layer of chromium using chemical vapor deposition [17][18][19][20]. The master mold was then immersed in a release agent (1.0% Optool DSX; Daikin Co., Ltd.) for 1 hour, before the being treated with the same release agent in the gas phase for 12 hours.…”

Improvement in Transfer Performance for Antireflection Structured Films with Antifouling Properties via Partial-filling Technique

“…In addition, the liquid phase resin has no antifouling effect. To produce an antifouling effect at the resin surface, baking of the replicated ARS film was carried out at 85°C for 30 min [1,12].…”

“…The GC mold, fabricated at a high acceleration voltage (700 V), formed wide pitches that facilitated easy filling of the resin during UV-NIL. For the release treatment, a 30 nm-thick chromium layer was vacuum deposited as a metal layer on the surface of the processed GC by a vacuum evaporation machine (VPC-260F; ULVAC KIKO, Inc.) [9][10][11][12]. Thereafter, the mold was held in the liquid phase at 1 wt% Optool DSX (Daikin Industries, Ltd.) for 1 h, the vapor phase for 12 h, was baked at 120 °C for 5 min, and was finally immersed in a fluorinated solvent NOVEC 7300 (3M Japan Ltd.) [13].…”

Metallic Antireflection Structures Made from Silver Ink by a Liquid Transfer Imprint Lithography Technique

“…In addition, by using a roller [15,16], it is possible to obtain thin and uniform films regardless of the viscosity of the liquid. In this study, we fabricated metallic ARSs using silver ink and the LTIL process with a roll press.…”

“…Liquid transfer imprint lithography (LTIL) is a promising method for producing thin films under atmospheric conditions [12][13][14] because LTIL can reduce thickness of the residual layer of silver ink in the mold in the liquid phase [11,15]. In addition, by using a roller [15,16], it is possible to obtain thin and uniform films regardless of the viscosity of the liquid.…”