Electrochemical imprint lithography on Si surface using a patterned polymer electrolyte membrane

Abstract

Well-defined surface patterns can be applied to improve surface characteristics, optical properties, and wettability. Electrochemical imprint lithography is a promising method for fabricating micro/nanostructural patterns on material surfaces through low-cost procedures. However, this method typically requires a large amount of electrolyte and a complex electrochemical setup. Herein, we present a novel liquid-electrolyte-free electrochemical imprint lithography method involving the use of a patterned Nafion polymer electrolyte membrane. In this method, the Si material surface in contact with the patterned Nafion membrane is selectively oxidized through a liquid-electrolyte-free electrochemical method. Following the removal of the resulting oxide film by HF dipping, patterned structures with a width of 70–170 μm and a depth of 40 nm can be obtained on the Si surface. The etching depth increases proportionally with the electrolysis time. The presence of a liquid electrolyte between the Si surface and the Nafion membrane during electrolysis increases the width of the pattern formed on the Si surface. This indicates that the liquid-electrolyte-free electrochemical method facilitates more accurate pattern transformation on the Si surface than that involving the use of a liquid electrolyte. The dotted, hexagonal, and lattice patterned Si surfaces can be fabricated at room temperature by using the proposed method. The proposed liquid-electrolyte-free electrochemical imprint lithography method involving the use of a patterned Nafion membrane is a simple, environment-friendly direct imprinting process that can be applied for micropatterning on and surface functionalization of hard and stable materials.