Individually Addressable, Submicrometer Band Electrode Arrays. 1. Fabrication from Multilayered Materials

Abstract

Useful analytical application of submicrometer band electrodes depends strongly upon developing reproducible, convenient fabrication and characterization procedures. We report fabrication of arrays of individually addressable submicrometer band electrodes that are 2 mm long and functional down to 37.0 nm in width, using multilayered materials and conventional microfabrication techniques. Fabrication involves thermal vapor deposition of a chromium adhesion layer and a gold layer on glass, followed by plasma-enhanced chemical vapor deposition of a silicon nitride layer, photolithography, and reactive ion etching. The topography of each layer was studied using contact-mode atomic force microscopy. Surfaces show larger features as the thickness of gold increases. Silicon nitride topography shows a relatively smoother surface, indicating that it may serve as a planarizing layer for subsequent gold layers. Cyclic voltammetry at 0.10 V/s of individual band electrodes in a solution of Ru(NH3)63+ shows a typical sigmoidal response, as would be expected when the diffusion layer exceeds the smallest dimension of the electrodes. At faster scan rates, peak-shaped voltammograms are observed, as expected. Good reproducibility of electrochemical behavior was obtained for electrodes in the same array.