Direct fabrication of integrated 3D Au nanobox arrays by sidewall deposition withcontrollable heights and thicknesses

Abstract

This paper provides a unique strategy for controlling integrated hollow nanostructurearrays such as boxes or pillars at the nanometer scale. The key merit of this technique isthat it can overcome resolution limits by sidewall deposition and deposit various materialsusing a sputtering method. The sputtering method can be replaced by other dry depositiontechniques such as pulsed laser deposition (PLD) for complex functional materials.Furthermore, it can produce low-cost large-area fabrication and high reproducibility usingthe NIL (nanoimprint lithograph) process. The fabrication method consists of asequence of bilayer spin-coating, UV-NIL, RIE (reactive ion etching), sputtering,ion milling and piranha cleaning processes. By changing the deposition time andmolds, various thicknesses and shapes can be fabricated, respectively. Furthermore,the fabricated Au box nanostructure has a bending zone of the top layer and a∼17 nm undercut of the bottom layer as observed by SEM (scanning electron microscope). Thesidewall thickness was changed from 12 to 61 nm by controlling the deposition time, andwas investigated to understand the relationship with blanket thicknesses and geometriceffects. The calculated sidewall thickness matched well with experimental results. Usingsmaller hole-patterned molds, integrated nanobox arrays, with inner squares measuring∼160 nm, and nanopillar arrays, with inside pores measuring∼65 nm, were fabricated under the same conditions.