Method of plasma processing

Abstract

Plasma processing apparatus and plasma processing methods capable of maintaining etching characteristics and to prevent degradation of a lower electrode even when the focus ring is severely eroded by the plasma are disclosed. According to an exemplary embodiment, a side-surface protecting ring formed of a ceramic material having an erosion rate by the plasma lower than an erosion rate of the material of the focus ring is provided to cover the side surface of the lower electrode. As a result, it becomes possible to prevent the side surface of the lower electrode from being exposed to the plasma and maintain the etching characteristics even after the focus ring is severely eroded. Further, degradation of the lower electrode is decreased.

1 . A method of processing a substrate using a plasma, comprising: 
 providing a lower electrode in a processing chamber, the lower electrode having a supporting surface for supporting the substrate and a side surface connected to an outer perimeter of the supporting surface, the supporting surface having a size approximately the same as, or smaller than, a size of the substrate;    supporting the substrate on the supporting surface;    covering the side surface of the lower electrode by a side surface protecting ring formed of a ceramic material;    positioning an outer perimeter of the most outside part of the side surface protecting ring inside an outer perimeter of the substrate supported on the supporting surface;    surrounding the side surface of the lower electrode, which is covered by the side surface protecting ring, by a focus ring formed of a first material different from the ceramic material; and    processing a surface of the substrate by generating a plasma in the processing chamber, the processing including:    preventing, by the side surface protecting ring, the plasma from touching the side surface of the lower electrode; and    preventing, by the substrate supported on the supporting surface, charged particles in the plasma accelerated toward a direction perpendicular to the surface of the substrate from irradiating the side surface protecting ring.    
   
   
       2 . The method according to  claim 1 , wherein: 
 the focus ring prevents the plasma from touching the side surface protecting ring before the focus ring is eroded by the plasma; and    the side surface protecting ring prevents the plasma from touching the side surface of the lower electrode even after the focus ring is eroded by the plasma to an extent that the focus ring cannot prevent the plasma from touching the side surface of the lower electrode.    
   
   
       3 . The method according to  claim 1 , wherein the ceramic material has a different secondary electron emission coefficient than that of the first material.  
   
   
       4 . The method according to  claim 1 , wherein the side surface protecting ring is prevented by the substrate from being irradiated by the charged particles in the plasma accelerated toward the direction perpendicular to the surface of the substrate, even after the focus ring is eroded.  
   
   
       5 . The method according to  claim 1 , wherein said covering includes fitting the side surface protecting ring, which is prepared separately from the lower electrode, to the side surface of the lower electrode.  
   
   
       6 . The method according to  claim 1 , wherein: 
 the ceramic material is selected from the group consisting of alumina, aluminum nitride, silicon carbide, silicon nitride, zirconia, titanium nitride, YAG, alumina-silicate solid solution, and alumina-silicon nitride solid solution; and    the first material is selected from a group consisting of quartz, silicon, and engineering plastics.    
   
   
       7 . The method according to  claim 1 , wherein the ceramic material is alumina and the first material is quartz.  
   
   
       8 . A method of processing a substrate using a plasma, comprising: 
 providing a lower electrode in a processing chamber, the lower electrode having a supporting surface for supporting the substrate and a side surface connected to an outer perimeter of the supporting surface, the supporting surface having a size smaller than a size of the substrate;    supporting the substrate on the supporting surface;    covering the side surface of the lower electrode by a side surface protecting ring formed of a ceramic material;    positioning an outer perimeter of the most outside part of the side surface protecting ring inside an outer perimeter of the substrate supported on the supporting surface;    surrounding the side surface of the lower electrode, which is covered by the side surface protecting ring, by a focus ring formed of quartz;    processing a surface of the substrate by generating a plasma in the processing chamber, the processing including:    preventing, by the side surface protecting ring, the plasma from touching the side surface of the lower electrode; and    preventing, by the substrate supported on the supporting surface, charged particles in the plasma accelerated toward a direction perpendicular to the surface of the substrate from irradiating the side surface protecting ring.    
   
   
       9 . The method according to  claim 8 , wherein the ceramic material is selected from a group consisting of alumina, aluminum nitride, silicon carbide, silicon nitride, zirconia, titanium nitride, YAG, alumina-silicate solid solution, and alumina-silicon nitride solid solution.  
   
   
       10 . The method according to  claim 8 , wherein the ceramic material is alumina.  
   
   
       11 . The method according to  claim 8 , wherein said covering includes fitting the side surface protecting ring, which is prepared separately from the lower electrode, to the side surface of the lower electrode.