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   one or more ground elements spaced radially away from the substrate support, wherein the substrate support and the face plate cooperatively define a processing volume and the one or more electrodes are adapted to generate a tunable electric field inside the processing volume having axial and radial components.   
   
   
       2 . The apparatus of  claim 1 , wherein the one or more electrodes is disposed within the substrate support. 
   
   
       3 . The apparatus of  claim 1 , wherein a portion of at least one of the one or more electrodes is angled. 
   
   
       4 . The apparatus of  claim 1 , further comprising one or more tunable circuits coupled to at least one of the one or more ground planes. 
   
   
       5 . The apparatus of  claim 4 , further comprising one or more tunable circuits coupled to at least one of the one or more electrodes. 
   
   
       6 . The apparatus of  claim 1 , further comprising a DC power source coupled to at least one of the one or more electrodes. 
   
   
       7 . The apparatus of  claim 1 , wherein the face plate is divided into zones separated by one or more isolators. 
   
   
       8 . The apparatus of  claim 7 , further comprising isolators disposed between the one or more ground planes. 
   
   
       9 . The apparatus of  claim 1 , wherein at least one of the one or more ground planes is an RF mesh. 
   
   
       10 . The apparatus of  claim 1 , wherein at least one of the one or more ground planes is the chamber bottom. 
   
   
       11 . An apparatus for supporting a substrate in a processing chamber, comprising:
 a support surface;   a thermal control element disposed within the support surface;   an electrode disposed within the support surface, wherein the electrode has a first portion defining a first plane and a second portion defining an angled surface, and the angled surface intersects the first plane; and   a tuner coupled to the electrode.   
   
   
       12 . The apparatus of  claim 11 , further comprising an electronic filter coupled to the electrode. 
   
   
       13 . The apparatus of  claim 11 , wherein the support surface defines a second plane, and the first plane is substantially parallel to the second plane. 
   
   
       14 . The apparatus of  claim 11 , wherein the electrode is an RF mesh. 
   
   
       15 . A method of controlling the spatial distribution of a capacitively coupled plasma, comprising:
 positioning a first electrode inside a processing chamber;   positioning a first ground plane inside the processing chamber and facing the first electrode to define a processing volume; and   generating an electric field with axial and radial components inside the processing volume by application of RF power to the first electrode and DC power to the first ground plane.   
   
   
       16 . The method of  claim 15 , further comprising positioning a second ground plane inside the processing chamber. 
   
   
       17 . The method of  claim 15 , further comprising using the first ground plane to provide a path to ground for the RF power and to apply a voltage bias inside the processing volume. 
   
   
       18 . The method of  claim 16 , further comprising tuning at least one of the first and the second ground planes. 
   
   
       19 . The method of  claim 16 , wherein the second ground plane has a different shape from the first ground plane. 
   
   
       20 . The method of  claim 15 , wherein the ground plane has a shape defined by a plurality of intersecting surfaces.