Fabrication of Sub-50 nm Au Nanowires using Thermally Curing Nanoimprint Lithography

Abstract

As narrow as 50 nm metal nanowire array patterns were successfully fabricated by nanoimprint lithography (NIL) using thermally curable monomer based resin. Compared to conventional hot embossing lithography, which has used thermoplastic polymers such as PMMA as an imprint resin and thus process temperature and pressure are over 180°C and 50 bar, respectively, thermally curable monomer based resin enabled imprint process at relatively lower temperature (120°C) and pressure (20 bar). Due to the highly fluidic nature of monomer based liquid phase resin, residual layer was not observed after imprinting. Imprinted resist pattern was then treated with oxygen plasma for 5 seconds and 5 nm of Ti layer and 15 nm of Au layer was deposited by e-beam evaporation. The imprinted resist pattern was lifted-off by dipping into an organic solvent, such as acetone. As the result, as narrow as 50 nm Au nanowire array pattern with area of 30 mm × 40 mm was fabricated on a Si substrate. 30 mm × 40 mm of nanowire pattern area was not limited by nanoimprint process, but the laser interference lithography process, which was used to fabricated the master template for imprinting.