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Abstract

A method for selectively removing a layer of electrolytically dissoluble metal such as copper overplate from a substrate such as a low-k dielectric comprising: providing a substrate bearing on a major surface thereof a layer of electrolytically dissoluble metal, the metal layer serving as a dissoluble electrode and having a central region and an adjacent peripheral region; providing at least a first counterelectrode and a second counterelectrode; positioning the counterelectrodes opposite the metal layer and spaced from the metal layer and spaced from each other; in a first electrolytic step, passing an electric current between the first counterelectrode and the central region of the metal layer, wherein the first counterelectrode is cathodic with respect to the metal layer, and the first electrolytic step includes a first phase, a second phase, and a third phase and during the first phase the electric current is a low amperage current, during the second phase the electric current includes a train of anodic pulses having a short on time and a higher amperage than during the first phase, and during the third phase the current includes a train of higher amperage anodic pulses having a longer on time than the second phase or is DC current; and

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