Large Area, Facile Oxide Nanofabrication via Step-and-Flash Imprint Lithography of Metal-Organic Hybrid Resins

Step-and-flash imprint lithography (S-FIL) is a wafer-scale, high-resolution nanoimprint technique capable of expansion of nanoscale patterns via serial patterning of imprint fields. While S-FIL patterning of organic resins is well known, patterning of metal organic resins followed by calcination to form structured oxide films remains relatively unexplored. However, with calcination shrinkage, there is tremendous potential utility in easing accessibility of arbitrary nanostructures at 20 nm resolution and below. However, barriers to commercial adoption exist due to difficulties in formulating polymerizable oxide precursors with good dispensability, long shelf life, and resistance to auto-homopolymerization. Here we propose a solution to these issues in the form of a versatile resin formulation scheme that is applicable to a host of functional oxides (Al2O3, HfO2, TiO2, ZrO2, Ta2O5, and Nb2O5). This scheme utilizes a reaction of metal alkoxides with 2-(methacryloyloxy)ethyl acetoacetate (MAEAA), a polymerizable chelating agent. Formation of these inorganic coordination complexes enables remarkable resistance to auto-homopolymerization, greatly improving dispensability and shelf life, thus enabling full scale-up of this facile nanofabrication approach. Results include successively imprinted fields consisting of 100 nm linewidth gratings. Isothermal calcination of these structures resulted in corresponding shrinkage of 75-80% without loss of mechanical integrity or aspect ratio, resulting in 20 nm linewidth oxide nanostructures.