Journal of the Electrochemical Society, Vol.147, No.2, 586-591, 2000
Localized electrochemical deposition of copper microstructures
This work demonstrates the electrodeposition of micrometer-scale copper structures using a simple instrument based on the scanning electrochemical microscope (SECM). Copper columns of 25 mu m width up to about 2 mm high were deposited on different substrates and interconnects were grown within an integrated circuit package. In the present instrument electrodeposition is localized by applying a voltage between a closely spaced glass insulated Pt disk ultramicroelectrode, ca. 25 mu m diam, and a substrate, all immersed in a solution of acidified CuSO4. The potential, the concentration of the CuSO4, and the presence of organic additives were all found to affect the microstructure of the deposits and control the efficiency of the deposition. To demonstrate some of the possible applications of this technique, copper lines were grown between pads in an integrated circuit package and an antenna about 2 cm long was grown on a millimeter wave transmission line cantilever.