Patent ID: 9567685
Date: 2017-02-14
CPC Classifications: C25D

Claim:
1. An electroplating apparatus for electroplating a metal on a substrate, the apparatus comprising: (a) a plating chamber configured to contain an electrolyte, the plating chamber comprising a catholyte compartment and an anolyte compartment, wherein the anolyte compartment and the catholyte compartment are separated by an ion-permeable membrane; (b) a substrate holder configured to hold and rotate the substrate in the catholyte compartment during electroplating; (c) a primary anode positioned in the anolyte compartment of the plating chamber; (d) an ionically resistive ionically permeable element positioned between the ion-permeable membrane and the substrate holder, wherein the ionically resistive ionically permeable element is adapted to provide ionic transport through the element during electroplating; and (e) a secondary anode configured to donate plating current to the substrate, wherein the secondary anode is positioned such that the donated plating current does not cross the ion-permeable membrane separating the anolyte and catholyte compartments, and wherein the secondary anode is positioned such as to donate plating current through the ionically resistive ionically permeable element, wherein the ionically resistive ionically permeable element comprises at least three portions: (i) an outer, ionically permeable portion; (ii) a middle, ionically impermeable portion; and (iii) an inner, ionically permeable portion, wherein the apparatus is configured to donate plating current from the secondary anode through the outer, ionically permeable portion, but not through the inner ionically permeable portion.