Plasma processing apparatus and method of plasma processing

Abstract

Plasma processing apparatus and plasma processing methods capable of maintaining acceptable etching characteristics and to prevent degradation of a lower electrode even when the focus ring is severely eroded by the plasma, while leaving the plasma discharge conditions used in the conventional apparatus and methods substantially unchanged, are disclosed. According to an exemplary embodiment, a side-surface protecting ring formed of a ceramic material is provided to cover the side surface of the lower electrode such that an outer perimeter of the side-surface protecting ring is approximately aligned with, or inside, an outer perimeter of the substrate to be processed. As a result, the side-surface protecting ring does not influence the plasma characteristic.

1 . A plasma processing apparatus for processing a substrate using a plasma, comprising: 
 a lower electrode comprising 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 dimension approximately the same as, or smaller than, a dimension of the substrate;    a side surface protecting ring that covers the side surface of the lower electrode, the side surface protecting ring being formed of a ceramic material, an outer perimeter of the side surface protecting ring being positioned approximately aligned with, or inside, an outer perimeter of the substrate supported on the supporting surface; and    a focus ring that surrounds the side surface of the lower electrode covered by the side surface protecting ring, the focus ring being formed of a first material different from the ceramic material.    
   
   
       2 . The apparatus according to  claim 1 , wherein the ceramic material has a different secondary electron emission coefficient than that of the first material.  
   
   
       3 . The apparatus according to  claim 1 , wherein the outer perimeter of the side surface protecting ring is positioned inside the outer perimeter of the substrate.  
   
   
       4 . The apparatus according to  claim 1 , wherein the side surface protecting ring is prepared separately from the lower electrode and fitted to the side surface of the lower electrode.  
   
   
       5 . The method according to  claim 1 , wherein the ceramic material having an erosion rate by the plasma lower than an erosion rate of the first material.  
   
   
       6 . The apparatus according to  claim 5 , wherein the erosion rate of the ceramic material measured by an amount of erosion of the side surface protecting ring in a direction perpendicular to the side surface of the lower electrode is less than half the erosion rate of the first material measured by an amount of erosion of the focus ring in a direction perpendicular to a surface of the substrate supported on the supporting surface.  
   
   
       7 . The method according to  claim 1 , 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; and    the first material is selected from a group consisting of quartz, silicon, and engineering plastics.    
   
   
       8 . The apparatus according to  claim 1 , wherein the ceramic material is alumina, and the first material is quartz.  
   
   
       9 . A plasma processing apparatus for processing a substrate using a plasma, comprising: 
 a lower electrode comprising 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 dimension smaller than a dimension of the substrate;    a side surface protecting ring that covers the side surface of the lower electrode, the side surface protecting ring being formed of a ceramic material; and    a focus ring that surrounds the side surface of the lower electrode covered by the side surface protecting ring, the focus ring being formed of quartz.    
   
   
       10 . The apparatus according to  claim 9 , 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.  
   
   
       11 . The apparatus according to  claim 9 , wherein the ceramic material is alumina.  
   
   
       12 . The apparatus according to  claim 9 , wherein the side surface protecting ring is prepared separately from the lower electrode and fitted to the side surface of the lower electrode.  
   
   
       13 . 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 and a side surface connected to an outer perimeter of the supporting surface, the supporting surface having a dimension approximately the same as, or smaller than, a dimension of the substrate;    covering the side surface of the lower electrode by a side surface protecting ring formed of a ceramic material;    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;    supporting the substrate on the supporting surface; 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.    
   
   
       14 . The method according to  claim 13 , 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.    
   
   
       15 . The method according to  claim 13 , wherein the ceramic material has a different secondary electron emission coefficient than that of the first material.  
   
   
       16 . The method according to  claim 13 , wherein said covering includes positioning an outer perimeter of the side surface protecting ring approximately aligned with, or inside, an outer perimeter of the substrate supported on the supporting surface.  
   
   
       17 . The method according to  claim 13 , wherein said covering includes positioning an outer perimeter of the side surface protecting ring inside an outer perimeter of the substrate supported on the supporting surface.  
   
   
       18 . The method according to  claim 13 , 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.  
   
   
       19 . The method according to  claim 13 , 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.    
   
   
       20 . The method according to  claim 13 , wherein the ceramic material is alumina and the first material is quartz.  
   
   
       21 . 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 and a side surface connected to an outer perimeter of the supporting surface, the supporting surface having a dimension smaller than a dimension of the substrate;    covering the side surface of the lower electrode by a side surface protecting ring formed of a ceramic material;    surrounding the side surface of the lower electrode, which is covered by the side surface protecting ring, by a focus ring formed of quartz;    supporting the substrate on the supporting surface; 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.    
   
   
       22 . The method according to  claim 21 , 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.  
   
   
       23 . The method according to  claim 21 , wherein the ceramic material is alumina.  
   
   
       24 . The method according to  claim 21 , wherein said covering includes positioning an outer perimeter of the side surface protecting ring approximately aligned with, or inside, an outer perimeter of the substrate supported on the supporting surface.  
   
   
       25 . The method according to  claim 21 , 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.