Three-dimensional microfabrication by localized electrochemical deposition

A microfabrication technology capable of electrodepositing truly three-dimensional metal structures is introduced. Micrometer-scale nickel structures including a multicoiled helical spring have been fabricated. Electrodeposition is localized by placing a sharp-tipped electrode in a plating solution, near a substrate, and applying a voltage. Structures are built by moving the electrode appropriately with respect to the substrate. Vertical deposition rates of 6 /spl mu/m/s are observed, two orders of magnitude greater than those of conventional electrodeposition. The theory of mass transport to a region of localized field is discussed, and a model of deposition profile is presented. The process can potentially produce submicrometer feature sizes using a range of materials including pure metals, alloys, and polymers.