Preparation of Epoxy/Silica and Epoxy/Titania Hybrid Resists via a Sol−Gel Process for Nanoimprint Lithography

Abstract

In this study, the solvent-free thermocurable epoxy/inorganic hybrid resists were prepared for low-pressure and moderate-temperature imprint lithography. Epoxy/silica and epoxy/titania hybrid resists were synthesized via a sol−gel process from a diglycidyl ether of bisphenol A prepolymer with a metal alkoxide precursor and a coupling agent, 3-glycidyloxypropyltrimethoxysilane. The introduction of the coupling agent results in the reinforced interfacial interaction between the epoxy resin and inorganic nanoparticles. Transmission electron microscopy analyses showed that the silica or titania particles were well-dispersed in the epoxy resin matrix on a nanometer scale without the formation of aggregates. The thermooxidative stability and the glass-transition temperature ( T g ) of the epoxy/silica nanocomposite showed improvement compared with the pure epoxy resin. When 10 wt % inorganic nanoparticles were added, the etching resistance of the epoxy/silica and epoxy/titania nanocomposites increased 4 and 3.2 times, respectively, compared with the pure epoxy resin. The epoxy/inorganic hybrid resist can be imprinted to obtain high-density patterns with a resolution of 110−500 nm on a flexible indium tin oxide/poly(ethylene terephthalate) substrate. The shrinkage of the epoxy/silica and epoxy/titania hybrid resist imprinted patterns decreased to 1.5% and 1.3%, respectively.