Electrodeposition of NiFe 3-D microstructures

Abstract

Many microelectromechanical systems incorporate magnetic materials such as electrodepo sited NiFe in electromagnetically driven microactuators. In these applications, the compositional structure of the NiFe deposit has a great impact on device performance. Thus, control of alloy composition during deposition is an important processing challenge. In this study, we report on the development of an electrodeposition process which allows the tailoring of the compositional structure in electrodeposited NiFe microstructures. Through fabrication of an electroplating device and control of plating electrolyte chemistry and mass transfer at the cathode surface we achieve unprecedented control of alloy composition. To illustrate the process, we first electrodeposit NiFe microstructures with uniform composition. Through understanding and continual optimization of the process, we realize greatly improved deposition rates and yields while maintaining compositional uniformity in geometrically complex microstructures. In the second part of the study, we use composition control to demonstrate the fabrication of new materials with spatially modulated composition. Precise spatial control of NiFe alloy composition allows creation of 3-dimensional electrodeposited NiFe microstructures.