Patent ID: 8623193

Claim:
A method of electroplating a layer of metal onto a thin conductive seed layer of a work piece surface having edge regions around a center region, the method comprising: a. making electrical connection to the seed layer at one or more locations on the edge regions, but not at the center region; b. positioning the work piece in a plating cell having an ionically resistive ionically permeable element, configured to improve plating uniformity, wherein the ionically resistive ionically permeable element has a porosity of 5% or less, a thickness of between about 5 and 25 millimeters, and wherein the element is positioned to have one surface facing the work piece surface, and located within about 5 millimeters of said work piece surface when the work piece is held in a plating position by a work piece holder; and c. delivering current through the plating cell via the electrical connections to the seed layer to electroplate the layer of metal on the seed layer, whereby the ionically resistive ionically permeable element introduces a circuit resistance in an ionic current path of the plating cell and at least partially compensates for a potential drop in the seed layer between edge regions and the center regions thereby promoting uniform plating across the seed layer on the work piece surface.