Patent ID: 8992723
Filing Date: 2015-03-31
Classification: H01J

Abstract:
1. Apparatus for coupling RF power to the interior of a plasma chamber, comprising: a plasma chamber having one or more electrically grounded chamber walls; a plasma chamber electrode that is within the plasma chamber and insulated from electrical ground, wherein the plasma chamber electrode includes first and second connection points, a back wall, a showerhead below the back wall, and an electrical conductor connected between the back wall and the showerhead; a gas inlet conduit extending through the center of the back wall, wherein the first and second connection points of the plasma chamber electrode are on the back wall on opposite sides of, and spaced away from, the gas inlet conduit; an RF bus conductor having a first end portion, a second end portion and a central portion connected between the end portions, wherein the first and second end portions are parallel to each other and the central portion is perpendicular to the end portions such that the RF bus conductor has a U-shape circumventing the gas inlet conduit, and wherein the first and second end portions respectively include first and second connection points that are respectively connected to the first and second connection points of the plasma chamber electrode by conductive legs; and an RF return bus conductor that is distinct from each of the electrically grounded chamber walls and that is electrically connected to one of the electrically grounded chamber walls, wherein the RF return bus conductor includes a first end portion, a second end portion, and a central portion that respectively are parallel to the first end portion, the second end portion, and the central portion of the RF bus conductor such that the RF return bus conductor has a U-shape parallel to the U-shape RF bus conductor; wherein: said central portion of the RF bus conductor includes a first surface between the first and second connection points of the RF bus conductor that is rectangular, planar and has a length greater than one-half the distance between the first and second connection points of the plasma chamber electrode; the central portion of the RF return bus conductor includes a second surface positioned parallel and face-to-face with said first surface of the RF bus conductor, wherein the second surface is rectangular, planar, and has a length greater than one-half the distance between the first and second connection points of the plasma chamber electrode; the first surface of the RF bus conductor is closer to the second surface of the RF return bus conductor than it is to any of the electrically grounded chamber walls that are parallel to the first surface; and no portion of the RF bus conductor between the first and second connection points of the RF bus conductor is electrically connected to the plasma chamber electrode.