Template-assisted multilayer electrodeposition: An approach to top-down designable, surface/volumetric hierarchical nanostructures

Abstract

Driven by the emerging interest in the design and realization of structures with co-existing micro- and nanoscale features, various nanofabrication approaches are being developed. We show that the selective, conformal growth of a multilayer structure is a promising route for the controlled realization of various structures with size-hierarchy, including both surface (i.e., the structures of which functionalities are characterized by the interaction between their surface, and external systems, such as self-cleaning, superhydrophic substrates with dual-scale topography), and volumetric (i.e. composite materials of which functionalities rely on the intrinsic properties of nanostructures distributed throughout their volume, such as giantmagnetoresistance sensors) structures. This is realized based on a sequential multilayer electrodeposition guided by an insulating substrate with predesigned topography, referred to as template-assisted multilayer electrodeposition process. Various multiscale, multidimensional surface and volumetric hierarchical structures are demonstrated of which size scale of the nanostructures are defined by the individual layer deposition parameters, while their position and overall geometry are defined by that of the template. These structures include (1) large area (> 1 cm^2), planar, or non-planar surfaces comprised of anisotropic, nanoscale surface relief structures of wide-ranging size scale (10 nm-1 micron); and (2) thick (10-100 micron), volumetric composite material in which individual metallic layers of micron, or submicron scale thicknesses are electrically insulated from the adjacent layers by interlamination insulating layers of similar thicknesses. The utility of the fabricated structures is evaluated in a few potential application domains, i.e., nanolithography, self-cleaning, and high frequency magnetic devices.