Edge ring assembly with dielectric spacer ring

Abstract

An edge ring assembly surrounds a substrate support surface in a plasma etching chamber. The edge ring assembly comprises an edge ring and a dielectric spacer ring. The dielectric spacer ring, which surrounds the substrate support surface and which is surrounded by the edge ring in the radial direction, is configured to insulate the edge ring from the baseplate. Incorporation of the edge ring assembly around the substrate support surface can decrease the buildup of polymer at the underside and along the edge of a substrate and increase plasma etching uniformity of the substrate.

1 . An edge ring assembly adapted to surround a substrate support surface in a plasma etching chamber comprising: 
 an edge ring dimensioned so as to underlie a substrate located on a substrate support surface in the chamber and provide a clearance gap between a lower surface of the substrate and an upper surface of the edge ring; and    a dielectric spacer ring between the edge ring and the substrate support surface dimensioned so as to provide a clearance gap between a lower surface of a substrate located on the substrate support surface and an upper surface of the dielectric spacer ring.    
   
   
       2 . The edge ring assembly of  claim 1 , wherein the dielectric spacer ring is bonded to an upper surface of a coupling ring or an upper surface of a baseplate.  
   
   
       3 . The edge ring assembly of  claim 1 , wherein a radial gap between the edge ring and the dielectric spacer ring and/or a radial gap between the dielectric spacer ring and the substrate support surface is less than 0.25 mm.  
   
   
       4 . The edge ring assembly of  claim 1 , wherein the dielectric spacer ring has a width of from about 0.5 to 2.5 mm and a height of from about 1 to 3 mm.  
   
   
       5 . The edge ring assembly of  claim 1 , wherein the dielectric spacer ring comprises an axially upward extending portion formed on a radially inner surface of a coupling ring.  
   
   
       6 . The edge ring assembly of  claim 1 , wherein an upper surface of the dielectric spacer ring and an innermost upper surface of the edge ring are substantially co-planar when the dielectric spacer ring and the edge ring are mounted in the chamber.  
   
   
       7 . The edge ring assembly of  claim 2 , wherein the dielectric spacer ring and/or the coupling ring are made of quartz.  
   
   
       8 . The edge ring assembly of  claim 1 , wherein the edge ring is made from silicon, silicon carbide, aluminum oxide, aluminum nitride, silicon nitride, quartz or combinations thereof.  
   
   
       9 . The edge ring assembly of  claim 1 , wherein a radially outer portion of the edge ring is thicker than the dielectric spacer ring.  
   
   
       10 . The edge ring assembly of  claim 2 , further comprising at least one gas passage extending through the coupling ring or the baseplate, the gas passage being adapted to supply a heat transfer gas to an adjacent surface of the edge ring and/or the dielectric spacer ring.  
   
   
       11 . A plasma etching chamber including an edge ring assembly adapted to surround a substrate support surface in the plasma etching chamber comprising: 
 a substrate support having a substrate support surface;    an edge ring dimensioned so as to underlie a substrate and provide a clearance gap between a lower surface of a substrate located on the substrate support surface in the chamber and an upper surface of the edge ring; and    a dielectric spacer ring between the edge ring and the substrate support surface dimensioned so as to provide a clearance gap between a lower surface of a substrate located on the substrate support surface and an upper surface of the dielectric spacer ring.    
   
   
       12 . The plasma chamber of  claim 11 , wherein a substrate is mounted on the substrate support surface such that the outer edge of the substrate overhangs the dielectric spacer ring and a radially inner portion of the edge ring.  
   
   
       13 . The plasma chamber of  claim 12 , wherein the dielectric spacer ring has a width effective to electrically insulate the edge ring from the baseplate and a height effective to minimize polymer deposition in a gap between the dielectric spacer ring and the substrate.  
   
   
       14 . The plasma chamber of  claim 11 , wherein the distance between a plane of the substrate support surface and a plane of the upper surface of the dielectric spacer ring is less than about 0.25 mm, and the distance between a plane of the substrate support surface and a plane of the upper surface of a radially inner portion of the edge ring is less than about 0.25 mm.  
   
   
       15 . The plasma chamber of  claim 12 , wherein a gap between a lower surface of the substrate and an upper surface of the dielectric spacer ring is less than about 0.25 mm, and a gap between a lower surface of the substrate and an upper surface of a radially inner portion of the edge ring is less than about 0.25 mm.  
   
   
       16 . The plasma chamber of  claim 11 , wherein the plasma etching chamber comprises a parallel plate reactor having an upper showerhead electrode facing the substrate support.  
   
   
       17 . The plasma chamber of  claim 11 , wherein the substrate support comprises an RF driven electrode.  
   
   
       18 . The plasma chamber of  claim 11 , wherein the substrate support comprises an electrostatic chuck.  
   
   
       19 . The plasma chamber of  claim 11 , wherein the edge ring assembly is adapted to reduce at least one of (i) RF coupling between the edge ring and the baseplate, (ii) arcing between edge ring and the baseplate, and (iii) polymer deposition on an underside and/or edge of a substrate supported on the substrate support surface.  
   
   
       20 . A method of etching a layer formed on a semiconductor substrate in the plasma etching chamber of  claim 11 , the method comprising the steps of: 
 supporting the semiconductor substrate on the substrate support surface positioned inside the chamber;    supplying etching gas to the chamber;    forming a plasma adjacent an exposed surface of the substrate; and    etching one or more layers formed on the semiconductor substrate with the plasma.    
   
   
       21 . A method of replacing the dielectric spacer ring in the plasma etching chamber of  claim 11 , comprising removing the dielectric spacer ring from the chamber and replacing it with another dielectric spacer ring after etching a predetermined number of semiconductor substrates.  
   
   
       22 . A dielectric spacer ring dimensioned so as to provide a clearance gap between a lower surface of a substrate located on a substrate support surface in a plasma etching chamber and an upper surface of the dielectric spacer ring, the dielectric spacer ring being further dimensioned so as to be surrounded by an edge ring dimensioned so as to underlie the substrate and provide a clearance gap between a lower surface of the substrate and an upper surface of the edge ring.  
   
   
       23 . The dielectric spacer ring of  claim 22 , wherein the dielectric spacer ring has a width of from about 0.5 to 2.5 mm and a height of from about 1 to 3 mm.  
   
   
       24 . The dielectric spacer ring of  claim 22 , wherein the dielectric spacer ring comprises an axially upward extending portion formed on a radially inner surface of a coupling ring.  
   
   
       25 . The dielectric spacer ring of  claim 22 , wherein an upper surface of the dielectric spacer ring and an innermost upper surface of the edge ring are substantially co-planar when the dielectric spacer ring and the edge ring are mounted in the plasma etching chamber.  
   
   
       26 . The dielectric spacer ring of  claim 22 , wherein the dielectric spacer ring is made of quartz.  
   
   
       27 . The dielectric spacer ring of  claim 22 , wherein the dielectric spacer ring has a width of from about 0.95 to 1.0 mm and a height of from about 2.5 to 2.7 mm.  
   
   
       28 . The dielectric spacer ring of  claim 22 , wherein the dielectric spacer ring is adapted to surround an ESC in a plasma etch chamber and the dielectric spacer ring has a width less than an overhang of a wafer supported on the ESC.  
   
   
       29 . The dielectric spacer ring of  claim 24 , wherein the dielectric spacer ring and coupling ring consist of a single piece of quartz material.