Supply of controlled amount of polishing slurry to semiconductor wafers

Abstract

An apparatus is disclosed wherein polishing slurry is supplied to a polishing pad affixed to a polishing platen to thereby polish semiconductor wafers. This apparatus is provided with at least one slurry-supply mechanism for supplying a controlled amount of polishing slurry to an intermediate region between outer end and central regions of a semiconductor wafer and to the central region per se. Control is made such that the amount of flow of polishing slurry supplied to the intermediate region of the semiconductor wafer is larger than that supplied to the central region thereof.

What is claimed is:  
     
         1 . A method of polishing a semiconductor wafer, comprising the steps of: 
 pressing said semiconductor wafer against a surface of a polishing pad affixed to a polishing platen that is rotating in one direction; and    supplying polishing slurry to the surface of said polishing pad in such a manner that the amount of flow of polishing slurry supplied to an intermediate region between central and outer end regions of said semiconductor wafer is larger than that supplied to said central region.    
     
     
         2 . An apparatus for polishing a semiconductor wafer, comprising: 
 a polishing pad affixed to a polishing platen that rotatates in one direction;    at least one wafer holding head for holding a semiconductor wafer and for pressing said semiconductor wafer against a surface of said polishing pad while rotating in one direction; and    at least one slurry-supply mechanism for supplying polishing slurry to an intermediate region between outer end and central regions of said semiconductor wafer and said central region, respectively, while controlling the amount of flow of said polishing slurry in such a manner that the amount of flow of polishing slurry supplied to the former is larger than that supplied to the latter.    
     
     
         3 . The apparatus according to  claim 2 , wherein said slurry-supply mechanism comprises: 
 a pair of first slurry-supply nozzles disposed side by side in a direction corresponding to a radial direction of said polishing pad and confronting said intermediate regions between the outer end and central regions of said semiconductor wafer;    a second slurry-supply nozzle disposed between first slurry supply nozzles and confronting said central region of said semiconductor wafer; and    a flow amount varying means for independently supplying the controlled amount of polishing slurry to said pair of first slurry-supply nozzles and said second slurry-supply nozzle.    
     
     
         4 . The apparatus according to  claim 3 , wherein said flow amount varying means comprises a pump.  
     
     
         5 . The apparatus according to  claim 2 , wherein said slurry-supply mechanism comprises: 
 a guide bar extending in a radial direction of said polishing pad;    one or blocks movably disposed on said guide bar;    one or two slurry-supply nozzles each mounted on an associated block; and    means for fixing said each block to said guide bar.    
     
     
         6 . The apparatus according to  claim 2 , wherein said slurry-supply mechanism comprises: 
 a block mounting thereon a slurry-supply nozzle and accommodating therein a nut;    a feed screw being engagement with said nut and mounted on a bracket; and    a pulse motor for rotationally driving said feed screw.    
     
     
         7 . The apparatus according to  claim 2 , wherein said slurry-supply mechanism comprises: 
 one or two guide bars each extending in a radial direction of said polishing pad;    one or two blocks guided by an associated guide bar and accommodating therein a nut;    one or two feed screws each being in engagement with the nut of an associated block;    one or two slurry nozzles each mounted on an associated block; and    one or two pulse motors each rotationally driving an associated feed screw.