an apparatus for performing ion incident angle control while processing a substrate within a processing chamber is provided . the apparatus includes an edge ring surrounding the substrate disposed on a lower electrode , wherein the edge ring is electrically isolated from the lower electrode . the edge ring receives a first voltage from an edge ring direct current voltage control arrangement , resulting in an edge ring potential . the apparatus also includes a radio frequency source that provides power to the lower electrode and a gas distribution system that delivers gases into the processing chamber to interact with power to generate plasma to process the substrate . during processing , the edge ring dc voltage control arrangement is adjusted to cause the edge ring potential to be higher than the dc potential on the substrate , thereby causing the plasma to have a non - uniform angular ion distribution profile for processing the substrate edge .