Back flash imprint lithography for transparent plastic substrates Wen-chang Liao a , Steve Lien-Chung Hsu a, * , Sheng-Yuan Chu b , Po-Ching Kau b a Department of Materials Science and Engineering, National Cheng-Kung University, 1 Ta-Hsueh Road, Tainan 701-01, Taiwan, ROC b Department of Electrical Engineering, National Cheng-Kung University, Tainan 701-01, Taiwan, ROC Received 3 July 2004; accepted 4 November 2004 Available online 20 November 2004 Abstract A new and low-cost process, back flash imprint lithography (BFIL), has been developed for use in resist pattern transfer on flexible transparent plastic substrates. This technique uses a two-layer plate, which contains a transparent plastic substrate coated with an UV-curable resist. The plate is heated over the resistÕs softening point. Then a non- transparent mold is pressed to the resist layer. After cooling to room temperature, an UV-light is applied from the substrate side to photocure the resist. After the separation of mold and the resist layer, the desired patterns can be trans- ferred to the resist completely. Ó 2004 Elsevier B.V. All rights reserved. Keywords: Back flash imprint lithography; Flexible transparent plastic substrate; UV-curable polymer 1. Introduction Imprint lithography has emerged as a promising technology for definition micro- and nano-scale patterns. Due to its simplicity, low cost and high resolution, imprint lithography has drawn a lot of attention in recent years [1–3]. There are several different approaches for imprint lithography. The mold-assisted lithography (MAL), and step and flash imprinting lithography (SFIL) based on pho- topolymerization of monomers have been pro- posed as alternatives for imprinting lithography at room temperature besides the most commonly used hot embossing lithography (HEL) [4–6]. The SFIL, which uses photosensitive polymers as the etching barrier, is shown in Fig. 1 [6]. In the SFIL technique, a transparent mold made from quartz or glass is required to allow the UV light to pass through, and photocure the resist. 0167-9317/$ - see front matter Ó 2004 Elsevier B.V. All rights reserved. doi:10.1016/j.mee.2004.11.003 * Corresponding author. Tel.: +886 6 2757575x62904; fax: +886 6 2346290. E-mail address: lchsu@mail.ncku.edu.tw (S.L.-C. Hsu). Microelectronic Engineering 77 (2005) 250–254 www.elsevier.com/locate/mee