Method and apparatus for controlling local current to achieve uniform plating thickness

Abstract

A process for electroplating metallic features of different density on a surface of a substrate comprises providing an electroplating bath having an anode, immersing the substrate into the electroplating bath, spaced from the anode, the substrate comprising a cathode. Positioned in the electroplating bath between the substrate and the anode, and adjacent to and separated from the substrate surface is a second cathode that includes a wire mesh screening portion having openings of different sizes conforming to the metallic features to be electroplated. The second cathode screening portion has openings of larger size adjacent areas of higher density of features to be electroplated and openings of smaller size adjacent areas of lower density of features to be electroplated. The process further includes impressing a current through the electroplating bath between the substrate and the anode, and between the second cathode and the anode, and electroplating the metallic features of different density onto the substrate.