Fabrication of inexpensive metallic mould for nanoimprinting using colloidal monolayer as a nanomask

Abstract

In this paper, we demonstrate a technique to fabricate nanostructure in an inexpensive way. A layer of polystyrene (PS) beads (650 nm diameter) was coated to get monolayer on silicon oxide substrate. The gap created between the aligned PS beads was used to deposit metals like Cr, Al, and Au using sputtering and e-beam evaporation techniques. The nano sphere acted as a mask to generate array of metallic nano structures. The thickness of deposited metal was varied to achieve varying height of the structures. Removal of the PS beads was done using di-chloromethane. Silicon oxide substrate along with the regularly aligned metallic nano structure thus formed, acted as a metallic mould for nanoimprinting. The pattern was then imprinted on a thin PMMA layer. Nano cavities created on the PMMA layer were of the order of metallic nano structure. Spot lithography was used to create rectangles to define the regions (or spots) of confinement for nanosphere. These regular nano pattern generated could be optimized to get good quality nano structures and has apparent application in photonic crystal formation and other nano application.