Fabrication of three-dimensional hybrid nanostructures by an integrated process comprising nanoimprint lithography and layer-by-layer assembly

Abstract

The fabrication of three-dimensional (3D) nanostructures, which have sub-100 nm dimensions in all three directions that can be changed independently for each dimension, is a key issue of nanotechnology. E-beam writing can provide high-resolution two-dimensional (2D) nanopatterns, but implementation of pattern replication methods for rapid reproduction of a master and self-assembly, to provide patterned growth of structures, is essential for the development of more general and versatile 3D nanofabrication methodologies. Here the integration of top-down nanoimprint lithography (NIL) and bottom-up layer-by-layer self-assembly (LBL-SA) are described for the preparation of 3D hybrid nanostructures. NIL provided down to sub-100nm poly(methylmethacrylate) (PMMA) structures. These were employed to fabricate patterned self-assembled monolayers of cyclodextrin (CD) host molecules on silicon oxide. The consecutive LBL-SA with adamantyl guest-functionalized dendrimers and CD-modified gold nanoparticles resulted in patterned multilayer structures with thicknesses of 3-30 nm. The x, y control by NIL and the z control (albeit the same height for all nanostructures simultaneously) by LBL-SA ultimately allowed the fabrication of circular structures with a radius of 25 nm and a thickness of 20 nm. The integration of the two methods has thus yielded a versatile 3D nanofabrication methodology comprising 10-40 process steps.