Mesoscale Metallic Pyramids with Nanoscale Tips

NU 2005-026

Inventors

Joel Adam Henzie

Teri Odom*

Eun Kwak

Short Description

A facile top-down process for fabricating anisotropic mesoscale (100-300 nm) metallic pyramids, with nanoscale tips (radii of curvature < 2 nm)

Abstract

Northwestern researchers have developed a facile top-down process for fabricating anisotropic mesoscale (100-300 nm) metallic pyramids with nanoscale tips (radii of curvature < 2 nm). In this process mesoscale holes in a chromium film are used as an etch mask to fabricate pyramidal pits in a silicon substrate, then this same mask is used as a deposition mask to form the metallic pyramids. This process involves a combination of phase-shifting photolithography (PSP), wet-chemical etching, and electron (e)-beam deposition, and two- and three-layered pyramids of different metals and chemical functionality can be created. The simple procedure employs sub-250 nm holes in a chromium film as both an etch mask and deposition mask. The technique affords multi-layered, pyramidal structures utilizing the layer-by-layer capabilities of e-beam deposition. The top-down nanofabrication method produces anisotropic structures that are monodisperse (>95%), highly uniform in shape and size, and multi-functional. The orientation-dependent plasmon resonance modes of the metallic nanoparticles can be generated when aligned inside a uniform dielectric environment. The broad nanoparticle optical tunability from ultraviolet to near-infrared wavelengths can be exploited in nanoscale AFM, photonics, chemical and biological sensing, and photovoltaic applications.

Applications