Minimizing oxygen inclusion when electroplating high saturation density CoFe for microelectromechanical system

Abstract

Co-Fe alloys with a high saturation flux density Bs are used as soft magnetic materials in various microelectromechanical system applications. The electroplating process to deposit this material was widely researched. This paper describes experimental investigations to optimize the Co-Fe electroplating process. Besides the high saturation flux density Bs and other magnetic properties, mechanical and chemical properties like low film stress and good corrosion resistance also have to be considered. In these experiments, test electrolytes with different additives were used. The main purpose of those additives is to avoid the oxidation of Fe2+ to Fe3+ in the electrolyte to minimize the formation of Fe (OH)3 and its integration in the deposited film. Vibrating sample magnetometer measurements were applied to characterize the magnetic properties. The composition of Fe and Co in the deposited film was determined by energy dispersive x-ray spectroscopy. An electron probe microanalyzer was used to determine the impurities (O, S, and B) in the deposits. The results show different efficiencies of the applied additives improving the plating process. © 2010 American Institute of Physics.