Retaining ring for chemical mechanical polishing, its operational method and application system

Abstract

A retaining ring for CMP is disclosed. The retaining ring has a plurality of grooves. The grooves have rounded sidewalls. Because the sidewalls of the grooves of the retaining ring are rounded, the slurry is not apt to accumulate around them and the pad is less scratched. Accordingly, the micro-scratches on the wafer surface are reduced and the yield of the CMP step is increased. Its operational method and application system are also disclosed in this invention.

1 . A retaining ring for CMP characterized in that said retaining ring comprises a plurality of grooves with sidewalls which all comprise first rounded corners. 
     
     
         2 . The retaining ring for CMP of  claim 1 , wherein said retaining ring comprises 12-24 grooves. 
     
     
         3 . The retaining ring for CMP of  claim 1 , wherein said retaining ring comprises an inner periphery comprising a second rounded corner. 
     
     
         4 . The retaining ring for CMP of  claim 1 , wherein said retaining ring comprises an outer periphery comprising a third rounded corner. 
     
     
         5 . The retaining ring for CMP of  claim 1 , wherein said grooves further comprise at least one opening comprising at least one fourth rounded corner. 
     
     
         6 . A CMP method for fixed abrasives, comprising:
 providing a wafer, a retaining ring comprising a plurality of grooves comprising a first rounded corner, a polishing pad and a flat sub-pad, wherein said wafer is in the center of said retaining ring and on said polishing pad, the active surface of said wafer contacts said polishing pad and said flat sub-pad supports said polishing pad; and   promoting said retaining ring moving relatively against said polishing pad in the presence of a slurry, wherein said polishing pad comprises 5-50% a plurality of fixed abrasives, said slurry comprises L-proline and fluoroaliphatic esters surfactants, and said retaining ring provides a 0.5-3.0 psi downward force to make the active surface of said wafer contact said polishing pad.   
     
     
         7 . The method of  claim 6 , wherein said retaining ring comprises 12-24 grooves. 
     
     
         8 . The method of  claim 6 , wherein said retaining ring comprises an inner periphery comprising a second rounded corner. 
     
     
         9 . The method for CMP of  claim 6 , wherein said retaining ring comprises an outer periphery comprising a third rounded corner. 
     
     
         10 . The method of  claim 6 , wherein said grooves further comprise at least one opening comprising at least one fourth rounded corner. 
     
     
         11 . The method of  claim 6 , wherein said fixed abrasives are selected from the group consisting of ceria and silica. 
     
     
         12 . A CMP system for fixed abrasives, comprising:
 a retaining ring comprising a plurality of grooves comprising rounded corners for fixing a wafer;   under said retaining ring a polishing pad comprising said fixed abrasives and contacting said retaining ring;   at least one driving device for driving said retaining ring to move relatively against said polishing pad; and   at least one slurry provider for providing said wafer, said retaining and said polishing pad with a slurry.   
     
     
         13 . The CMP system of  claim 12 , wherein said polishing pad comprises 5-50% said fixed abrasives. 
     
     
         14 . The CMP system of  claim 12 , wherein said slurry comprises L-proline and fluoroaliphatic esters surfactants. 
     
     
         15 . The CMP system of  claim 12 , wherein said retaining ring provides a 0.5-3.0 psi downward force. 
     
     
         16 . The CMP system of  claim 12 , further comprising a flat sub-pad for supporting said polishing pad. 
     
     
         17 . The CMP system of  claim 12 , wherein said retaining ring comprises 12-24 grooves. 
     
     
         18 . The CMP system of  claim 12 , wherein said retaining ring comprises an inner periphery comprising a second rounded corner. 
     
     
         19 . The CMP system of  claim 12 , wherein said retaining ring comprises an outer periphery comprising a third rounded corner. 
     
     
         20 . The CMP system of  claim 12 , wherein said grooves further comprise at least one opening comprising at least one fourth rounded corner. 
     
     
         21 . The CMP system of  claim 12 , wherein said fixed abrasives are selected from the group consisting of ceria and silica.