Load bearing insulator in vacuum etch chambers

Abstract

An upper electrode assembly (UEL) is supported in an insulator in an opening in the top of an etch chamber in which large diameter substrates are processed with a flange of the UEL overlying the chamber wall around the opening with the insulator in between so that the insulator experiences primarily compressive and minimal shear loads. The electrode nonetheless fills the otherwise vacuum space between the UEL and the chamber wall above a shield ring that covers the insulator and portions of the adjacent UEL face and chamber wall.

1 . A method of supporting a downwardly facing RF electrode in an opening in the top of a: vacuum processing chamber that is configured to process a wafer of at least 200 millimeters in diameter, the opening having a diameter larger than the diameter of the wafer to be processed, the method comprising: 
 providing an annular insulator having: 
 outer and inner integral portions,  
 the outer portion having: 
 an outside diameter larger than the diameter of the opening, and  
 a downwardly facing support surface, and  
 
 the inner portion: 
 extending below the downwardly facing support surface of the outer portion, and  
 having: 
 an outside diameter smaller than the diameter of the opening,  
 an inside diameter larger than that of the wafer to be processed, and  
 an upwardly facing support surface;  
 
 
   providing an upper electrode assembly having: 
 a flange at the top thereof that has an outside diameter that is larger than the diameter of the opening, and  
 a lower electrode face: 
 formed of a material compatible with the process to be performed on the wafer in the chamber, and  
 having an outside diameter larger than the diameter of the wafer to be processed;  
 
   providing an electrically non-conductive shield ring having: 
 an outside diameter that is greater than the outside diameter of the inner portion of the insulator, and  
 an inside diameter that is less than the outside diameter of the lower electrode face of the upper electrode assembly;  
   placing the upper electrode assembly and the annular insulator in the opening and securing the shield ring adjacent the lower electrode face such that: 
 the downwardly facing support surface of the insulator rests on the top of the chamber around the opening,  
 the flange at the top of the upper electrode assembly rests on the upwardly facing support surface of the inner portion of the insulator and compresses the insulator between the flange and the chamber wall,  
 the insulator substantially fills the volume between: 
 the outside diameter of the lower electrode face and the inside diameter of the opening, and  
 the downwardly facing support surface of the insulator and the shield ring; and  
 
   coupling an RF power source between the electrode and the chamber.    
   
   
       2 . The method of  claim 1  wherein: 
 the vacuum processing chamber is configured to process a wafer of at least 300 millimeters in diameter.    
   
   
       3 . An insulator for supporting an upper electrode assembly (UEL) in an opening in the top of a processing chamber of a semiconductor wafer etching apparatus, the insulator comprising: 
 an annular ring formed at least in part of electrically insulating material and having integral outer and inner portions;    the inner portion having an inner diameter of greater than 200 millimeters and an upwardly facing electrode supporting surface having an outer diameter to support a UEL thereon;    the outer portion having a downwardly facing supporting surface having an inner diameter to support the insulator with the UEL supported thereon on a chamber wall around the opening in the top of a chamber, whereby at least a portion of the downwardly facing supporting surface aligns vertically with the upwardly facing supporting surface; and    the inner portion having a lower part configured to extend sufficiently below the top of the chamber to support a shield ring thereon in the processing chamber, the lower part being configured to displace substantially all vacuum space between the UEL and the top of the chamber and between the UEL and the shield ring.    
   
   
       4 . The insulator of  claim 3  wherein the annular ring is formed of the electrically insulating material throughout.  
   
   
       5 . The insulator of  claim 3  wherein the ring is formed of a metal core material having a coating of the electrically insulating material thereon.  
   
   
       6 . The insulator of  claim 5  wherein the coating is an anodic layer.  
   
   
       7 . The insulator of  claim 5  wherein the coating contains at least one column III element.  
   
   
       8 . The insulator of  claim 5  wherein the coating contains at least one element selected from the group consisting of Yttrium, Scandium, Lanthanum, Cerium, Dysprosium, and Europium.  
   
   
       9 . The insulator of  claim 5  wherein the coating contains at least one element selected from the group consisting of Y 2 SO 3 , Sc 2 O 3 , Sc 2 F 3 YF 3 , La 2 O 3 , Y 2 SO 3 CeO 2 , Eu 2 O 3  and DyO 3 .  
   
   
       10 . The insulator of  claim 3  wherein the ring is formed of a material selected from the group consisting of alumina, quartz, ceramic material, silicon, silicon nitride, sapphire, polymide and silicon carbide.  
   
   
       11 . A processing apparatus comprising the insulator of  claim 3  and further comprising: 
 a vacuum chamber wall portion having an inner diameter defining the opening, the downwardly facing supporting surface of the outer portion of the insulator resting on the chamber wall portion; and    an upper electrode assembly having a downwardly facing rim having an outer diameter that is greater than the inner diameter of the wall portion, at least an outer portion of the rim of the upper electrode assembly resting on the upwardly facing surface of the insulator and being vertically aligned with the insulator and the wall portion.    
   
   
       12 . A processing apparatus comprising: 
 a vacuum chamber wall portion having an inner diameter defining an opening therein;    an upper electrode assembly (UEL) having a lower face of a diameter greater than 200 millimeters and less than the inner diameter of the wall portion and having a downwardly facing rim having an outer diameter greater than the inner diameter of the wall portion;    an insulator supporting the UEL in the opening, the insulator including an annular ring formed at least in part of electrically insulating material;    at least a portion of the insulator lying between and in vertical alignment with at least a portion of the rim of the UEL and the wall portion;    an annular shield ring having an outer diameter greater than the inner diameter of the wall portion and an inner diameter less than the diameter of the lower face of the UEL; and    at least a portion of the insulator displacing substantially all vacuum space that is surrounded by the UEL, the chamber wall portion and the shield ring.    
   
   
       13 . The apparatus of  claim 12  wherein: 
 the UEL has a lower face of a diameter greater than 300 millimeters.