Journal of the Electrochemical Society, Vol.147, No.5, 1810-1817, 2000
High resolution 3D microstructures made by localized electrodeposition of nickel
Techniques to create three-dimensional microstructures are still a matter of research, and localized electrodeposition is a promising path to inexpensive free-form microfabrication in metal. The principle is to put the tip of a needle very close to a conducting substrate submerged in a plating bath, apply typically 4-5 V, and move the tip as the metal deposits. In this paper we report improved deposition control and the benefits of adding ammonia and ammonium formate to nickel plating solutions for enhanced resolution and surface smoothness. A mirror-smooth 600 mu m tall nickel column 3 mu m in diameter was built at 3 mu m/s. Still higher axial deposition rates could be attained, as well as structure diameters down to 2 mu m. The broadening of previously built structures near the one being grown was studied, and the usefulness of an auxilliary electrode was confirmed. The possibility of branching and joining structures was also investigated in order to realize the vision of building structures of arbitrary shapes.