(Electrodeposition Division Early Career Investigator Award Address) Metal Patterning by Electrodeposition: Local Bipolar Electrochemistry and Additive-Derived Electrode Bifurcation

Abstract

One of electrodeposition’s highest value applications is in manufacturing of electronic devices, ranging in scale from nanometer connections in integrated circuits up to millimeter scale features in printed circuit boards. The wide-range of feature geometries and substrate complexity (conducting, semiconducting, insulating, etc.) in this constantly evolving industry has driven extensive efforts to tailor both lateral and vertical material growth characteristics, diverging from more traditional electroplating applications focused on uniform films as applied to coatings. Like the electronics industry, techniques for 3D control of electrodeposition are consistently evolving. These methods include deposition through patterned masks (through-mask plating), use of sacrificial materials to form patterns (EFAB), localized electrodeposition using confined electrodes, and surface adsorbates that drive spatially-dependent active/passive regions through the coupling of local chemical and electrical gradients.In this presentation, I will highlight recent advances in two of these areas: electrodeposition through confined electrodes and by influencing deposition kinetics with surface adsorbates. In the former, bipolar electrochemistry is combined with microjet electrodes to permit localized electrodeposition of a ‘pixel’ on a conductive surface without requiring electrical contact; patterns are produced by rastering the microjet similar to commercial 3D-printing methods. In the latter, electrolyte additives that inhibit deposition can induce spontaneous formation of spatially bifurcated active and passive regions; characteristics of the electrode topography, surface heterogeneity, and electro(chemical) transport through the cell determine the shape of 2D pattern formation. Electroanalytical measurements of these active/passive systems inform electrode shape-change models describing the interplay between transport and electrochemical kinetics. This fundamental insight permits control of an otherwise random bifurcation process that can be tailored for a variety of applications.