Chemical mechanical polishing apparatus and method to minimize slurry accumulation and scratch excursions

Abstract

A pad cleaning device ( 210, 220, 250 ) is used in conjunction with spray rinse water to thoroughly clean a polishing pad ( 110 ) of a chemical-mechanical polishing system ( 100 ) after a wafer ( 120 ) has been polished. A sprayer or sprayer extension ( 210, 220, 250 ) is strategically positioned and securely retained on a portion of the dispensing arm ( 130 ) and adapted for applying a rinse water spray directly to the center portion ( 150 ) of the pad preventing conglomerated slurry from accumulating.

1 . An apparatus for cleaning a polishing pad of a chemical-mechanical polishing system which includes a first drive device coupled with said polishing pad for turning said polishing pad on a center axis in a first direction and a second drive device for bring said wafer into mechanical contact with said polishing pad and for rotating said wafer in a direction opposite to said first direction, comprising:; 
 a dispenser located in proximity above said polishing pad and adapted for dispensing a slurry to said polishing pad, said slurry is cooperable with said mechanical contact for effecting polishing of said wafer, said dispenser further including a plurality of nozzles each for delivering a wash solution to said polishing pad for cleaning said slurry from said polishing pad; and    an extension adapted for coupling to a distal end of said dispenser for delivering said wash solution to an area proximate to said center axis for cleaning said slurry from said polishing pad.    
   
   
       2 . The apparatus of  claim 1 , wherein said extension includes piping and a spray nozzle, said piping coupled to and extending from said dispenser toward said center axis, said spray nozzle coupled to said piping and cooperable therewith to direct a water spray to said polishing pad at a ninety degree angle.  
   
   
       3 . The apparatus of  claim 2 , wherein said extension further includes a adjustor coupled to said piping for extending the distance of the spray nozzle from said extension distal end.  
   
   
       4 . The apparatus of  claim 2 , wherein said spray nozzle is held in a position by said piping on said center axis directly above said polishing pad.  
   
   
       5 . The apparatus of  claim 1 , wherein said dispenser dispensing said wash material to said polishing pad all along an area from the circumference of said polishing surface to said center axis.  
   
   
       6 . The apparatus of  claim 1 , wherein said extension is adapted to deliver said wash solution to an area proximate to said center axis without any portion of said extension extending past the distal end of said dispenser toward said center axis.  
   
   
       7 . A system for chemical mechanical polishing of semiconductor wafers, said system comprising: 
 a first drive device coupled with a polishing pad of a circular shape and adapted to turn said polishing pad on a center axis in a first direction;    a dispenser located in proximity above said polishing pad and adapted for dispensing a slurry to said polishing pad;    a second drive device for bring said wafer into mechanical contact with said polishing pad and rotating said wafer in a direction opposite to said first direction and cooperable with said dispensed slurry for effecting polishing of said wafer;    said dispenser further including a plurality of nozzles each for delivering a wash solution to said polishing pad and an extension adapted for coupling to a distal end of said dispenser for delivering said wash solution to an area proximate to said center axis for cleaning said slurry from said polishing pad.    
   
   
       8 . The system of  claim 7 , wherein said extension includes piping and a spray nozzle, said piping coupled to and extending from said dispenser toward said center axis, said spray nozzle coupled to said piping and cooperable therewith to direct a water spray to said polishing pad at a ninety degree angle.  
   
   
       9 . The system of  claim 8 , wherein said extension further includes a adjustor coupled to said piping for extending the distance of the spray nozzle from said extension distal end.  
   
   
       10 . The system of  claim 8 , wherein said spray nozzle is held in a position by said piping on said center axis directly above said polishing pad.  
   
   
       11 . The system of  claim 7 , wherein said extension is adapted to deliver said wash solution to an area proximate to said center axis without any portion of said extension extending past the distal end of said dispenser toward said center axis.  
   
   
       12 . A method for cleaning a polishing pad in a chemical mechanical polishing system, comprising the steps: 
 imparting relative motion to said polishing pad, wherein said polishing pad is rotated about a center axis which is perpendicular to the polishing surface of said polishing pad;    dispensing a wash material directly to the most center portion of said polishing surface about said axis.    
   
   
       13 . The method of  claim 12 , wherein said wash material is dispensed from a spray extension which is coupled to the dispensing arm of said chemical mechanical polishing system.  
   
   
       14 . The method of  claim 12  further comprising dispensing a de-ionized water solution directly to the most center portion of the polishing surface about said axis following polishing of a semiconductor wafer.  
   
   
       15 . The method of  claim 12  further comprising dispensing wash material from said dispensing arm to said polishing pad all along an area from the circumference of said polishing surface to said axis.