Tunable ground planes in plasma chambers

Abstract

An apparatus and method are provided for controlling the intensity and distribution of a plasma discharge in a plasma chamber. In one embodiment, a shaped electrode is embedded in a substrate support to provide an electric field with radial and axial components inside the chamber. In another embodiment, the face plate electrode of the showerhead assembly is divided into zones by isolators, enabling different voltages to be applied to the different zones. Additionally, one or more electrodes may be embedded in the chamber side walls.

1 . An apparatus for processing a substrate, comprising:
 a substrate support;   one or more electrodes coupled to the substrate support;   a showerhead assembly having a face plate opposing the substrate support; and   a tunable ground element coupled to the substrate support, the tunable ground element having an angled edge.   
     
     
         2 . The apparatus of  claim 1 , wherein the tunable ground element is disposed within the substrate support. 
     
     
         3 . The apparatus of  claim 1 , wherein the tunable ground element is electrically coupled to a tuning circuit. 
     
     
         4 . The apparatus of  claim 3 , wherein the tuning circuit comprises a DC power source. 
     
     
         5 . The apparatus of  claim 2 , further comprising a second tunable ground element disposed within the substrate support. 
     
     
         6 . The apparatus of  claim 2 , further comprising an electrode embedded in a side wall of the chamber. 
     
     
         7 . The apparatus of  claim 2 , wherein the face plate is divided into zones separated by one or more isolators, and each zone is electrically coupled to a different RF source. 
     
     
         8 . The apparatus of  claim 6 , wherein the face plate is divided into zones separated by one or more isolators, and each zone is electrically coupled to a different RF source. 
     
     
         9 . The apparatus of  claim 1 , wherein tunable ground element is an RF mesh. 
     
     
         10 . An apparatus for processing a substrate, comprising:
 a substrate support;   one or more electrodes coupled to the substrate support;   a showerhead assembly having a face plate opposing the substrate support, the face plate comprising at least two zones separated by isolators; and   a tunable ground element coupled to the substrate support, the tunable ground element having an angled edge.   
     
     
         11 . The apparatus of  claim 10 , wherein the tunable ground element is embedded in the substrate support. 
     
     
         12 . The apparatus of  claim 11 , further comprising an electrode embedded in a side wall of the chamber, wherein each zone of the face plate is electrically coupled to a different RF source. 
     
     
         13 . The apparatus of  claim 11 , further comprising a second tunable ground element coupled to the substrate support. 
     
     
         14 . The apparatus of  claim 13 , further comprising an electrode embedded in a side wall of the chamber. 
     
     
         15 . The apparatus of  claim 10 , wherein the tunable ground element is an RF mesh. 
     
     
         16 . The apparatus of  claim 13 , wherein a radius of the tunable ground element is different from a radius of the second tunable ground element. 
     
     
         17 . The apparatus of  claim 11 , wherein the tunable ground element is electrically coupled to a tuning circuit having a DC power source. 
     
     
         18 . The apparatus of  claim 12 , wherein the tunable ground element is electrically coupled to a tuning circuit having a DC power source. 
     
     
         19 . The apparatus of  claim 13 , wherein each of the tunable ground elements is electrically coupled to a separate tuning circuit, each tuning circuit having a DC power source. 
     
     
         20 . An apparatus for processing a substrate, comprising:
 a substrate support;   a showerhead assembly having a face plate opposing the substrate support, and together with the substrate support defining a processing volume between the face plate and the substrate support, the face plate coupled to an RF source;   one or more electrodes embedded in the substrate support and electrically coupled to a tuning circuit comprising a DC power source, the electrode having a first portion that defines a plane and a second portion that defines a surface intersecting the plane; and   an electrode embedded in a side wall of the chamber proximate to the processing volume.