Etch rate uniformity using the independent movement of electrode pieces

Abstract

A plasma reactor comprises a chamber, a bottom electrode, a top electrode, a bottom grounded extension adjacent to and substantially encircling the bottom electrode. The top grounded extension adjacent to and substantially parallel to the top electrode. The top electrode is also grounded. The top grounded extension is capable of being independently raised or lowered to extend into a region above the bottom grounded extension.

1 . A plasma reactor comprising: 
 a chamber;    a bottom electrode and a top electrode enclosed within said chamber;    a bottom grounded extension adjacent to and substantially encircling said bottom electrode;    a top grounded extension adjacent to and substantially parallel to said top electrode;    wherein said top grounded extension is capable of being independently raised and lowered to extend into a region above said bottom grounded extension.    
   
   
       2 . The plasma reactor of  claim 1  wherein said top grounded extension includes a ring.  
   
   
       3 . The plasma reactor of  claim 1  wherein said bottom grounded extension includes a ring.  
   
   
       4 . The plasma reactor of  claim 1  further comprising a power supply coupled to said bottom electrode, said bottom electrode configured to receive a workpiece.  
   
   
       5 . The plasma reactor of  claim 4  wherein said power supply generates a plurality of frequencies to said bottom electrode.  
   
   
       6 . The plasma reactor of  claim 5  wherein said top electrode is grounded.  
   
   
       7 . A method for using a plasma reactor having a chamber with a top electrode, a bottom electrode, a bottom grounded extension adjacent to and substantially encircling said bottom electrode, a top grounded extension adjacent to and substantially parallel to said top electrode, the method comprising: 
 adjusting a position of the top grounded extension, the top grounded extension capable of being independently raised and lowered to extend into a region above the bottom grounded extension.    
   
   
       8 . The method of  claim 7  further comprising supplying power to the bottom electrode, the bottom electrode configured to receive a workpiece.  
   
   
       9 . The method of  claim 8  further comprising generating a plurality of frequencies to the bottom electrode.  
   
   
       10 . The method of  claim 7  further comprising grounding the top electrode.