Enhancement of spatial resolution of microfabricated columns using localized electrochemical deposition

Abstract

This paper reports on the effect of using an analog feedback technique and electrode rotation on the Localized Electrochemical Deposition (LECD) process to enhance the spatial resolution and dimensional control during the growth of nickel micro-columns. Results shown here present the capability of the process for the fabrication of microstructures with high spatial resolution. Experiments were conducted on a specially assembled apparatus where nickel structures were electrodeposited onto Cu cathodes from a nickel sulfamate plating solution, using a non-soluble anode electrode. In the first part of our work, growth of the columns was found to be zero, partial or complete depending on the vertical traverse speed of the microelectrode away from the horizontal copper surface. In this case, dimensional control was limited. Efforts to overcome the said limitation in the second part achieved a constant growth rate with an analog closed-loop feedback control of the process. This improved technique produced columns with more even and controlled dimensions, therefore allowing for better spatial resolution of the structures. This was followed by deposition with electrode rotation, which produced columns with annulus cross-sections, indicating the existence of a uniform hollow core in the columns. This feature and dimensional control in the growth of the columns were not observed when using a stationary electrode - a novel development in the area of LECD and a possibility of fabricating micro-pipes for micro drug-delivery systems.