TiO<sub>2</sub>-SiO<sub>2</sub> Radical-Based Gas-Permeable Mold for High-Precision UV Nanoimprint Lithography

Nanoimprint lithography, a technique within microfabrication, continues to progress due to its ability to pattern large areas with high resolution, efficiency, and cost-effectiveness. Among its variants, UV nanoimprint lithography offers rapid curing through UV light and exceeds thermal nanoimprint lithography in terms of the throughput. However, UV nanoimprint lithography often traps air during the imprinting process and molds made from non-gas-permeable materials such as quartz and metal can result in molding defects. In this study, a new TiO2-SiO2 radical-based gas-permeable mold surface material was developed using the sol-gel method to enhance ultraviolet-based nanoimprint lithography for precise processing. Compared to existing material, this surface material exhibited superior performance in terms of both gas permeability and mechanical properties, with oxygen gas permeability 1.2 times higher, carbon dioxide gas permeability 1.3 times higher, and flexural strength 1.1 times higher than those of existing material. Based on these performance enhancements, the microfabrication demonstrated superior transfer accuracy compared to master molds with specifications of (a) pitch: 20 μm, height: 17.1 μm, bottom diameter: 7.14 μm, and (b) pitch: 50 μm, height: 17.0 μm, bottom diameter: 7.14 μm, achieving (a) height 99.9%, bottom diameter 99.0%, and (b) height 99.8%, bottom diameter 94.1%. Additionally, these gas-permeable molds facilitated high-precision fine processing on the surface of lactic acid-glycolic acid copolymers, reaching (a) bottom diameter of 95.3% and (b) 93.7%, respectively. The findings from this study will advance precision processing technology, improve the accuracy of fine processing in machine tools, and enhance production efficiency. This is particularly anticipated to aid the development of advanced production systems in sectors such as medical devices, semiconductor manufacturing, optical components, and microfluidic devices, thereby promoting future industrial growth.