Effects of polyethyleneimine, applied potential and the initial gap on the localized electrochemical deposition of silver microcolumns

Abstract

Localized electrochemical deposition (LECD) is a promising and economical three-dimensional (3D) microstructure fabrication method. As the current research on LECD mainly focuses on the deposition of copper and nickel, this work investigated the fabrication of silver microcolumns via LECD, using polyethyleneimine (PEI) as an additive. Firstly, the effects of PEI on the surface morphologies and structures of the deposited microcolumns were studied; it was found that adding PEI to the electrolyte could reduce the column surface roughness and promote the formation of uniform and straight columnar structures. Thereafter, the effects of the deposition voltage and initial electrode spacing on the LECD process performance were studied using a 0.08- g/L PEI electrolyte; nanoindentation was performed to determine the hardness and Young's modulus of the silver microcolumns. Furthermore, based on the experimental results, a possible action mechanism for PEI and the formation mechanism of the microcolumns' nodular structures were proposed. This technology was used to manufacture high-density and high-quality interconnects and electrodes for electrochemical biosensors.