Mechanistic Study for Facile Electrochemical Patterning of Surfaces with Metal Oxides

Abstract

Reactive interface patterning promoted by lithographic electrochemistry serves as a method for generating submicrometer scale structures. We use a binary-potential step on a metallic overlayer on silicon to fabricate radial patterns of cobalt oxide on the nanoscale. The mechanism for pattern formation has heretofore been ill-defined. The binary potential step allows the electrochemical boundary conditions to be controlled such that initial conditions for a scaling analysis are afforded. With the use of the scaling analysis, a mechanism for producing the observed pattern geometry is correlated to the sequence of electrochemical steps involved in the formation of the submicrometer structures. The patterning method is facile and adds to electrochemical micromachining techniques employing a silicon substrate.

Lithography‐Free Electrochemical Patterning of Conductive Substrates with Metal Oxides

“…The RIPPLE method is based on applying linear sweep voltammetry to drive concerted etching and patterning of a redox‐active layer overlaid with a resist. The linear sweep procedure over a defined voltage window has been modified to use binary‐potential steps, which allows control of the dimensions and spacing of the electrochemically generated pattern . We have found RIPPLE to be useful for applications not requiring the high resolution offered by classical lithography techniques.…”

“…When trying to fabricate large patterns containing many rings from a single opening, this tightening of gaps between rings becomes detrimental to pattern formation (Figure S1, Supporting Information). The decrease in ring spacing may be remedied by increasing the duration of each successive potential step . However, this strategy adds time to the electrochemical procedure and the ideal durations are empirically difficult to assess.…”

“…The linear sweep procedure over a defined voltage window has been modified to use binary-potential steps, which allows control of the dimensions and spacing of the electrochemically generated pattern. [13] We have found RIPPLE to be useful for applications not requiring the high resolution offered by classical lithography techniques. One particularly useful application of RIPPLE is for integrated Reactive interface patterning promoted by lithographic electrochemistry serves as a facile method for generating submicron structures on conductive substrates.…”

“…This tightening of rings is attributed to an increased concentration of (semi)metal ion near the edge of where the redox-active film is being etched (the etch front) due to diffusion constraints inherent in the etch front's expansion from the opening. [13] When trying to fabricate large patterns containing many rings from a single opening, this tightening of gaps between rings becomes detrimental to pattern formation ( Figure S1, Supporting Information). The decrease in ring spacing may be remedied by increasing the duration of each successive potential step.…”

“…The decrease in ring spacing may be remedied by increasing the duration of each successive potential step. [13] However, this strategy adds time to the electrochemical procedure and the ideal durations are empirically difficult to assess. With the goal of simplifying the overall process of patterning in this fashion, we assess the influence of resist properties on pattern formation and the implications of altering the resist.To understand the role of the resist in pattern formation, the nature of the resist was varied.…”