Nanoimprint lithography (NIL) is a very useful technique for the fabrication of nanopatterns, and it is used in some practical applications. The key issue for mass production is the understanding of the lifetime and deterioration of the release coating on the mold surface, because the adhesion of polymer materials on the mold surface results in defective products. However, a method for inspecting the durability and evaluating the release layer on the mold surface has not yet been established. This paper describes a method for inspecting the deterioration of the release-coated mold surface using the macro-optical inspection method, which is based on the detection method using edge-reflected light. This macroinspection enables the evaluation of the nonuniformity of the surface and local defects on the macroscale (from 0.1 to several millimeters), because the edge-reflected light is very sensitive to undulations in the surface morphology. In order to examine the deterioration of the release-coated mold surface, a silicon mold with 220 nm diameter holes and a fluorine release agent were used. For the release agent treatment, the mold was first dipped into 0.1% release agent for 30 min. Then, the mold was removed from the release agent and baked at 100 °C for 3 min on a hot plate, after which several undulations were observed. After three such treatments, the overcoating of the release agent caused a lot of defects such as water marks, stripes, and coating nonuniformities. Thus, the macroinspection method enables a facile understanding of the differences in such surface undulations. In order to evaluate the lifetime and deterioration, the UV-NIL process was carried out 100 times. The results showed that the macroinspection method reveals the thin-release-layer behavior during the UV-NIL process and the deterioration and undulation of the release layer.
Macro-optical inspection method for deterioration evaluation of release-coated mold surfaces for nanoimprint lithography
Jun Taniguchi, Junki Takahashi, Mitsuru Uda, Atushi Kohayase, Kenichi Kotaki; Macro-optical inspection method for deterioration evaluation of release-coated mold surfaces for nanoimprint lithography. J. Vac. Sci. Technol. B 1 November 2011; 29 (6): 06FC02. https://doi.org/10.1116/1.3646885
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