Patent ID: 8826855

Claim:
A confinement ring useful as a component of a capacitively-coupled plasma processing chamber wherein inner surfaces of the confinement ring provide an extended plasma confinement zone surrounding a gap between an upper electrode and a lower electrode on which a semiconductor substrate is supported during plasma processing in the chamber, the confinement ring comprising: an upper annular wall which extends horizontally and includes an annular flange at an inner end thereof adapted to underlie an outer edge of the upper electrode of the plasma chamber; a sidewall extending vertically downward from an outer end of the upper wall wherein the sidewall is free of openings except for a group of through holes arranged in 5 horizontal rows of evenly spaced holes having diameters of about 0.030 inch; and a lower annular wall extending horizontally inward from a lower end of the sidewall, the lower wall including circumferentially spaced apart radially extending slots, each of the slots having a length of at least 1.0 inch and a uniform width of 0.05 to 0.2 inch, the slots being evenly spaced at radial positions offset by no more than 2°; wherein the lower wall includes a downwardly extending annular projection at an inner perimeter thereof, the projection having a lower surface and the lower surface includes an electrically conductive coating.