Movable ground ring for movable substrate support assembly of a plasma processing chamber

Abstract

A movable ground ring of a movable substrate support assembly that includes a step configured to support a consumable isolation ring. The consumable isolation ring is configured to electrically isolate the movable ground ring from a dielectric ring of the movable substrate support assembly.

I claim: 
     
         1 . A movable ground ring of an adjustable gap capacitively-coupled plasma processing chamber, comprising:
 an annular bottom wall, an annular upper wall, an inner wall extending upwardly from an inner periphery of the bottom wall, a step at an upper end of the inner wall, the step formed by a horizontal surface extending inwardly from the inner wall and a vertical surface extending from the horizontal surface to the upper wall, the horizontal wall including a plurality of blind holes therein configured to receive vertically extending alignment pins which mate with recesses in a consumable isolation ring when mounted on the step.   
     
     
         2 . The movable ground ring of  claim 1 , wherein the step has a height of about 0.3 inch and a width of about 0.15 inch. 
     
     
         3 . The movable ground ring of  claim 1 , wherein the consumable isolation ring is supported thereon, the consumable isolation ring having a rectangular cross section with an inner diameter of about 14.8 inches, an outer diameter of about 15.1 inches, and a height of about 0.3 inch, and three recesses azimuthally spaced by 120° and disposed in a lower outer edge of the consumable isolation ring, each recess consisting of a single semi-cylindrical walled portion connected with a respective straight walled portion, wherein straight walled portions of each recess open on an outer surface of the consumable isolation ring, the straight walled portions having a width equal to the diameter of the respective semi-cylindrical walled portions and each recess has a depth of about 0.09 inch. 
     
     
         4 . The movable ground ring of  claim 1 , wherein the movable ground ring is configured to fit around and provide an RF return path to a fixed ground ring of a movable substrate support assembly configured to support a semiconductor substrate undergoing plasma processing. 
     
     
         5 . The movable ground ring of  claim 1 , wherein the movable ground ring is mounted on a fixed ground ring such that the movable ground ring is movable vertically with respect to the fixed ground ring. 
     
     
         6 . The movable ground ring of  claim 1 , wherein the movable ground ring is made of aluminum. 
     
     
         7 . The movable ground ring of  claim 1 , wherein an outer wall of the movable ground ring is configured to provide electrical contact with an inner end of a lower horizontal section of an electrically conductive confinement ring. 
     
     
         8 . The movable ground ring of  claim 1 , wherein the movable ground ring is supported on depressible plungers supported on a fixed ground ring of a substrate support assembly. 
     
     
         9 . The movable ground ring of  claim 8 , wherein the fixed ground ring includes three plunger support bores circumferentially spaced apart in an outer portion of a bottom wall, each of the plunger support bores engaging a plunger support housing containing depressible pins which extend above an upper surface of the bottom wall.