Polishing device and method

Abstract

A polishing device includes a polishing head for pressing and holding a semiconductor wafer, a pair of polishing pads having the same diameter as the polishing head for polishing the semiconductor wafer, and a subordinate polishing pad having a smaller diameter for polishing a peripheral portion of the semiconductor wafer. Both the pair of polishing pads are rotated in one direction, or in opposite directions. The rotational speed of the first and/or second polishing pad is controlled so that an equal polishing rate is obtained for the first and second polishing pads when the polishing pads are rotated in opposite directions.

1 . A polishing device comprising:
 a polishing head that holds a wafer while allowing rotation thereof; and   first and second polishing pads juxtaposed with each other in contact with a surface of the wafer held by said polishing head.   
     
     
         2 . The polishing device according to  claim 1 , said polishing head has a diameter substantially equal to a diameter of at least one of said first and second polishing pads. 
     
     
         3 . The polishing device according to  claim 2 , wherein said at least one of said first and second polishing pads include both said first and second polishing pads. 
     
     
         4 . The polishing device according to  claim 2 , wherein said first polishing pad has the diameter substantially equal to the diameter of said polishing head, and said second polishing pad has a diameter smaller than the diameter of said polishing head. 
     
     
         5 . The polishing device according to  claim 1 , further comprising a third polishing pad juxtaposed with said first and second polishing pads in contact with the surface of the wafer held by said polishing head, wherein said third polishing pad polishes a peripheral area of the surface of the wafer. 
     
     
         6 . The polishing device according to  claim 1 , wherein said first polishing pad includes a material different from a material of said second polishing pad. 
     
     
         7 . The polishing device according to  claim 1 , further comprising a polishing pad control unit that controls a rotational speed of said first polishing pad and/or said second polishing pad so that said first and second polishing pads have an equal polishing rate if said first and second polishing pads rotate in opposite directions. 
     
     
         8 . The polishing device according to  claim 7 , further comprising first and second dressers that dress said first and second polishing pads, respectively, wherein said polishing pad control unit further controls a rotational direction, rotational speed and pressure of at least one of said first and second dressers. 
     
     
         9 . A method for polishing a wafer by using the polishing device according to  claim 1 , said method comprising a first step including concurrent steps of rotating said first polishing pad, supplying slurry onto a surface of said first polishing pad, stopping rotation of said second polishing pad and supplying water onto a surface of said second polishing head. 
     
     
         10 . The method according to  claim 9 , further comprising a second step including concurrent steps of stopping rotation of said first polishing pad, supplying water onto a surface of said first polishing pad, rotating said second polishing pad, and supplying slurry onto a surface of said second polishing pad. 
     
     
         11 . The method according to  claim 10 , wherein a rotational direction of said first polishing pad in said first step is opposite to a rotational direction of said second polishing pad in said second step. 
     
     
         12 . The method according to  claim 11 , further comprising a third step including said consecutive steps of said first step, and a fourth step including said consecutive steps of said second step, wherein a rotational direction of said polishing head is different between said first step and said third step and between said second step and said fourth step. 
     
     
         13 . A method for polishing a wafer by using the polishing device according to  claim 1 , said method comprising a first step including concurrent steps of rotating said first and second polishing pads, and supplying slurry onto a surface of said first and second polishing pads. 
     
     
         14 . The method according to  claim 13 , wherein said first and second polishing pads rotate in opposite directions. 
     
     
         15 . The method according to  claim 14 , wherein a rotational direction of said polishing head is reversed during said first step.