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Keywords:

  • nanoimprint lithography;
  • oxides;
  • patterning;
  • alkoxides

Abstract

Direct patterning of oxides using thermal nanoimprint lithography is performed using either the sol-gel or methacrylate route. The sol-gel method results in resists with long shelf-life, but with high surface energy and a considerable amount of solvent that affects the quality of imprinting. The methacrylate route, which is limited to certain oxides, produces polymerizable resists, leading to low surface energy, but suffers from the shorter shelf-life of precursors. By combining the benignant elements from both these routes, a universal method of direct thermal nanoimprinting of oxides is demonstrated using precursors produced by reacting an alkoxide with a polymerizable chelating agent such as 2-(methacryloyloxy)ethyl acetoacetate (MAEAA). MAEAA possesses β-ketoester, which results in the formation of environmentally stable, chelated alkoxide with long shelf-life, and methacrylate groups, which provide a reactive monomer pendant for in situ copolymerization with a cross-linker during imprinting. Polymerization leads to trapping of cations, lowering of surface energy, strengthening of imprints, which enables easy and clean demolding over 1 cm × 2 cm patterned area with ≈100% yield. Heat-treatment of imprints gives amorphous/crystalline oxide patterns. This alliance between two routes enables the successful imprinting of numerous oxides including Al2O3, Ga2O3, In2O3, Y2O3, B2O3, TiO2, SnO2, ZrO2, GeO2, HfO2, Nb2O5, Ta2O5, V2O5, and WO3.