Fabrication of nanoscale structures with nanometer resolution and surface uniformity

Abstract

We integrated bottom-up and top-down techniques to develop a platform for the fabrication of structures with nanometer resolution and sub-nanometer surface uniformity, to serve as building-blocks of functional nanoscale devices and systems. By engineering surfaces and interfaces, chemically-synthesized gold (Au) nanoplates, with <1 nm surface roughness, are assembled to form nanogaps as small as ∼10 nm in width. Interconnects and contact pads are added using top-down lithography to introduce electrical functionality to the assembled nanogaps. A planarization technique is employed to eliminate nanometer-scale height variations across the gap due to the thickness inhomogeneity inherent to synthesized Au nanoplates. This is achieved by peeling the Au nanoplate electrodes as a uniform layer off the original substrate using an adhesive receiving surface, revealing the coplanar side originally in contact with the substrate. The peeling also eliminates edge defects and minimizes the surface roughness inherent to features formed through lithography. An extension of this technique demonstrates <5 nm vertical resolution in controlling the height variations between neighboring structures. Overall, the proposed technique provides a versatile platform to achieve nanometer resolution and surface uniformity essential in developing nanodevices for applications such as nanoelectromechanical systems, plasmonics, and molecular electronics.