Dry etching apparatus

Abstract

An etching chamber has a lower electrode section and an upper electrode section. A semiconductor wafer WF is mounted on the lower electrode section. An outer ring including a silicon (Si) ring disposed around the lower electrode section to provide a positioning assistance in mounting the semiconductor wafer WF, and an aluminum (Al) ring disposed under the Si ring. The Si ring virtually expands the area of a wafer WF when plasma is generated, such that unstable plasma around the wafer can be stabilized. To reduce localized abrasion and further stabilize plasma, the Si ring has a height-changing portion. The height-changing portion is formed of a curved surface in the innermost part and function to position the wafer WF.

What is claimed is:  
     
         1 . A dry etching apparatus having a chamber and plasmatizing an etching gas introduced into the chamber, the dry etching apparatus comprising: 
 a first electrode section provided in the chamber and having a support section for a semiconductor wafer;    a second electrode section provided in the chamber to face the first electrode section; and    an outer ring for mounting the semiconductor wafer, which is disposed around the first electrode section, 
 wherein the outer ring includes a height-changing portion formed of at least a curved surface on the innermost side.  
   
     
     
         2 . The dry etching apparatus as defined in  claim 1 ,  
       wherein the curved surface is concave.  
     
     
         3 . A dry etching apparatus having a chamber and plasmatizing an etching gas introduced into the chamber, the dry etching apparatus comprising: 
 a first electrode section provided in the chamber and having a support section for a semiconductor wafer;    a second electrode section provided in the chamber to face the first electrode section;    a first outer ring for mounting the semiconductor wafer which is disposed around the first electrode section; and    a second outer ring that is disposed below the first outer ring and has an internal diameter larger than the internal diameter of the first outer ring such that a distance from the second outer ring to the first electrode section is larger than the distance between the first outer ring and the first electrode section, 
 wherein the first outer ring includes on the innermost side a height-changing portion formed of at least a curved surface.  
   
     
     
         4 . The dry etching apparatus as defined in  claim 3 , 
 wherein the curved surface is concave.    
     
     
         5 . The dry etching apparatus as defined in  claim 3  and  4 , 
 wherein the first outer ring is changeable independent of the second outer ring.