A “thiol-ene” photo-curable hybrid fluorinated resist for the high-performance replica mold of nanoimprint lithography (NIL)

Abstract

Functional polyhedral oligomeric silsesquioxane (POSS)-based materials have been developed as an ideal material with high performance for nanoimprint lithography (NIL). A novel fluorinated hybrid resist as a soft mold for NIL, based on thiol-ene photopolymerization, was precisely designed and synthesized and is comprised of fluorinated mercaptopropyl polyhedral oligomeric silsesquioxane (POSS-F-SH) and a diluted crosslinker (2,2,3,3,4,4,5,5-octafluoro-1,6-hexyl diacrylate, DCFA₄). The obtained fluorinated hybrid resists possess a variety of characteristics desirable for UV-NIL, including low viscosity (16–239 cP), a low bulk volumetric shrinkage (4.8–7.5%) and a good resistance to oxygen inhibition. The cross-linked hybrid resins exhibited high transparency to UV light and resistance to organic solvents. As a soft mold, the excellent mechanical property (Young's modulus: 0.31–1.56 GPa) and low surface energy (14–20.4 mJ m⁻²) of the fluorinated polymers provide a clean mold release without fracture or deformation of the embossed structures. The thermally stability (T_d > 300 °C) render them capable of being used for both UV and thermal NIL duplication processes. The resultant soft mold exhibited a high resolution patterning capacity with feature sizes in the range of 200 nm to several microns. The economic efficiency of the mold fabrication, as well as the high durability and excellent releasing properties, could be quite valuable in NIL for the high-throughput fabrication of nano-devices.