US Patent 7544281 Uniform current distribution for ECP loading of wafers

An electrochemical plating apparatus and method for facilitating uniform current distribution across a wafer during loading into an ECP (electrochemical plating) apparatus is disclosed. The apparatus includes a bath container for containing a bath solution, an anode provided in the bath container, a cathode ring for supporting a wafer in the bath container and a current source electrically connected to the anode and the cathode ring. According to the method, a voltage potential is applied to the cathode ring as it is immersed into the solution and prior to immersion of the wafer in the solution, thereby facilitating a substantially uniform plating current across the wafer upon immersion of the wafer.