Patent ID: 8252140

Claim:
A plasma processing chamber configured for cleaning a bevel edge of a substrate, comprising: a bottom electrode having a bottom electrode surface for supporting the substrate when present, wherein the bottom electrode is coupled to a radio frequency (RF) power supply; a top edge electrode surrounding an insulating plate, the insulator plate opposing the bottom electrode, the top edge electrode being electrically grounded and separated from the insulator plate by a top dielectric ring, the top edge electrode having an L shape that is down-facing, wherein a vertical portion of the L shape is oriented horizontal, and the base portion of the L shape is oriented to face the bottom edge electrode; a bottom edge electrode, being electrically grounded, surrounds the bottom electrode and is separated from the bottom electrode by a bottom dielectric ring, the bottom edge electrode is oriented to oppose the top edge electrode; wherein the L shape defines a first separation and a second separation between the top and bottom edge electrodes, the first separation established by the vertical portion of the L shape that is oriented horizontal and is adjacent to the top and bottom dielectric rings, and the second separation is established by the base portion of the L shape that is spaced radially outward from the top and bottom dielectric rings; the first separation is greater than the second separation.