Abstract: An article, such as a semiconductor wafer (31), is selectively electrolytically plated to form metal deposits, such as contacts (26), adjacent to anodes of diode regions within such wafer by mounting the wafer in a plating chamber (36) opposite first and second electrodes (61 and 62), filling the chamber (36) with a metal plating electrolyte (49) and applying alternatingly plating pulses between the wafer (31) and the first electrode (61) and deplating pulses between the wafer (31) and the second electrode (62). The plating pulses are current controlled yielding a predetermined total plating current. The deplating pulses are voltage controlled yielding a deplating current which tends to subside in the course of the plating operation. The electrolyte in the chamber is agitated by streams of electrolyte pumped at a comparatively high rate toward the wafer (31) to break down surface layers of electrolyte adjacent to the wafer.

Abstract: A cylindrical surface of an article is electrolytically treated with a controlled, cross-sectional distribution of the electrolytic action. The distribution is achieved by placing the surface at a predetermined distance from a formed electrode to control the influence of the electrode on each portion of the surface along a cross section thereof. The influence on each such portion with respect to other portions of the surface is determined by the magnitude of an influence number associated with such portion in relation to the magnitude of similar influence numbers associated with the other surface portions along the cross section.