High-density pattern transfer via roll-to-roll ultraviolet nanoimprint lithography using replica mold

Abstract

Roll-to-roll ultraviolet nanoimprint lithography (RTR UV-NIL) has attracted much attention as a high-throughput nanofabrication process. In particular, high-density nanoscale line-and-space (L&S) patterns are widely used for optical devices and printed circuits, such as wire-grid polarizers and transparent electrode films. To realize a simplified high-throughput RTR process, the authors developed a replica roll mold fabrication process and examined the feed speed of RTR UV-NIL. The replica mold was fabricated by applying parallel-plate UV-NIL using a silicon master mold with 100-nm L&S patterns and 200-nm groove depth. Replica molds were coated with 10-nm-thick tungsten and a fluorinated silane coupling agent to prevent the adhesion of UV-curable resin during RTR UV-NIL. The release-coated replica molds were wrapped around roll substrate having a diameter of 150 mm. Using the replica mold, RTR UV-NIL was carried out at different UV doses, which were determined as the product of the UV light intensity and feed speed. The results confirmed that a sufficient UV dose enabled successful pattern transfer, while an insufficient UV dose caused the pattern to break down. In this experiment, a rapid feed speed of 18 m/min was possible under conditions of high UV light intensity. In addition, the release agent was still active after 500 revolutions of the replica roll mold (235.5 m).