Control over pattern fidelity and surface wettability of imprinted templates for flexible color filter manufacturing

This paper presents a universal approach for fabricating flexible color filter template with the high-fidelity patterns using R2R NIL in combination with microcontact printing which provides a solution for selective surface hydrophobization. The pattern transfer fidelity being critical in color filter manufacturing, as a function of imprinting parameters such as a roller pressure and web speed, is thoroughly investigated. We also discuss influence of various imprint resins, the thermal exposure and oxygen RIE on vertical dimensions measured using white-light scanning interferometer. Through the evaluation of all measurements of pattern height, the optimal R2R NIL process parameters are determined. By increasing the roll pressure and reducing the web speed, the pattern fidelity of a polymeric template is improved, reaching 93% of the original pattern height. The patterned surface is modified to achieve hydrophilicity and then locally printed with hydrophobic SAM. Channels become hydrophobic with WCA of 105° on the top and the uncoated regions at the bottom remain hydrophilic with WCA of 21°, exhibiting selective wetting. A high wettability contrast facilitates uniform ink filling into the channels and prevents ink diffusion during inkjet printing.

Graphical abstractA technique to fabricate a flexible template for color filter manufacturing is proposed, based on a replication of the high-fidelity pattern and subsequent tuning surface wettability via microcontact printing. The potentials of proposed approach are demonstrated by roll-to-roll imprint lithography combined with inkjet printing.Figure optionsDownload full-size imageDownload as PowerPoint slideHighlights► A flexible color filter template is fabricated by roll-to-roll imprinting. ► We find that increasing imprint pressure and lowering web speed improves the pattern fidelity. ► A high surface wettability contrast is achieved by microcontact printing. ► An imprinted template is selectively filled with color inks by inkjet printing.