Electrodeposition and Microstructure Characterization of Bimetallic Copper-Silver Films from the Methanesulfonic Acid Baths

Abstract

In this work, the bimetallic copper-silver deposits with variable compositions are prepared by electrodeposition from the methanesulfonate bath containing chloride ions. The precipitation of AgCl in this acid copper-silver bath can be avoided by the introduction of thiourea (TU) as the complexing agent. The composition and microstructure of such deposits are significantly affected by the introduction of TU, silver ion concentration, and deposition potential. The silver content varying from 0.7 to 43 w/o (weight percent) in the deposits is effectively adjusted by the systematic variation in the electrolyte composition and current density. The microstructures, such as the silver content, grain size, crystalline preferential orientation, and roughness of this series of Cu-Ag deposits are systematically compared for future electronic applications.