Assessment of release properties in UV nanoimprint lithography using high-aspect-ratio nanoscale molds

Abstract

Ultraviolet nanoimprint lithography (UV-NIL) is a potentially powerful tool for nanofabrication. However, the strong force required during the release step degrades the release coating layer, which leads to defects in pattern replication and eventual breakage of the mold. Therefore, optimal conditions for release coating are required. In addition, the recommended 1000 imprints for assessing the release properties in UV-NIL are extremely time consuming. The authors believed that the durability of the release layer could be varied by using a mold with a large surface area and previously fabricated such a mold to successfully transfer a high-aspect-ratio (>15) nanoscale pattern. In the present study, the authors used this method to investigate the optimal conditions for release coating and to assess the release properties in UV-NIL according to the measured release force and number of replication times. As a result, the conditions for release coating were optimized as follows: dipping time of 24 h, postrinsing bake temperature of 100 °C, and baking time of 3 min in a high-aspect-ratio mold with a 1300 nm pattern height. Low release force led to extended lifetime of the release coating layer in an accelerated durability test using a large-surface-area mold.