Polishing method

Abstract

A semiconductor wafer (W) and a polishing table ( 100 ) are rotated. The polishing table ( 100 ) has a polishing surface thereon. The semiconductor wafer (W) is pressed against the polishing surface on the polishing table ( 100 ) rotated at a first rotational speed to polish the semiconductor wafer (W). The semiconductor wafer (W) is separated from the polishing surface after the semiconductor wafer (W) is pressed against the polishing surface. Before the semiconductor wafer (W) is separated from the polishing surface, a rotational speed of the polishing table ( 100 ) is reduced to a second rotational speed lower than the first rotational speed to provide a difference between a rotational speed of the semiconductor wafer (W) and the rotational speed of the polishing table ( 100 ).

1 . A polishing method comprising: 
 rotating a workpiece;    rotating a polishing table having a polishing surface thereon;    pressing the workpiece against the polishing surface on the polishing table rotated at a first rotational speed to polish the workpiece;    separating the workpiece from the polishing surface after said pressing; and    before said separating, reducing a rotational speed of the polishing table to a second rotational speed lower than the first rotational speed to provide a difference between a rotational speed of the workpiece and the rotational speed of the polishing table.    
     
     
         2 . The polishing method as recited in  claim 1 , wherein said reducing is performed during said pressing.  
     
     
         3 . The polishing method as recited in  claim 1 , further comprising: 
 supplying a polishing liquid to the polishing surface at a first flow rate during said pressing; and    before or during said separating, increasing a flow rate of the polishing liquid to a second flow rate higher than the first flow rate.    
     
     
         4 . The polishing method as recited in  claim 1 , further comprising ejecting a mixture of gas and pure water or chemical liquid to the polishing surface to clean the polishing surface before said separating.  
     
     
         5 . The polishing method as recited in  claim 1 , wherein said separating comprises lifting the workpiece from the polishing surface.  
     
     
         6 . The polishing method as recited in  claim 5 , wherein said lifting comprises reducing a lifting speed of the workpiece until the workpiece has substantially been separated from the polishing surface.  
     
     
         7 . A polishing method comprising: 
 moving a workpiece and a polishing surface relative to each other;    pressing the workpiece against the polishing surface moved at a first frequency to polish the workpiece;    separating the workpiece from the polishing surface after said pressing; and    before said separating, reducing a frequency of movement of the polishing surface to a second frequency lower than the first frequency.    
     
     
         8 . The polishing method as recited in  claim 7 , wherein said moving comprising moving the workpiece and the polishing surface with an orbital movement.  
     
     
         9 . A polishing method comprising: 
 moving a polishing surface relative to a workpiece;    pressing the workpiece against the polishing surface moved at a first speed to polish the workpiece;    separating the workpiece from the polishing surface after said pressing; and    before said separating, reducing a speed of movement of the polishing surface to a second speed smaller than the first speed.    
     
     
         10 . The polishing method as recited in  claim 9 , wherein said moving comprising linearly moving the polishing surface.  
     
     
         11 . A polishing method comprising: 
 rotating a workpiece;    rotating a polishing table having a polishing surface thereon;    pressing the workpiece against the polishing surface on the polishing table;    separating the workpiece from the polishing surface after said pressing; and    before said separating, reducing a ratio of a rotational speed of the top ring to a rotational speed of the poslishing table.    
     
     
         12 . The polishing method as recited in  claim 11 , wherein said reducing is performed during said pressing.  
     
     
         13 . The polishing method as recited in  claim 11 , further comprising: 
 supplying a polishing liquid to the polishing surface at a first flow rate during said pressing; and    before or during said separating, increasing a flow rate of the polishing liquid to a second flow rate higher than the first flow rate.    
     
     
         14 . The polishing method as recited in  claim 11 , further comprising ejecting a mixture of gas and pure water or chemical liquid to the polishing surface to clean the polishing surface before said separating.  
     
     
         15 . The polishing method as recited in  claim 11 , wherein said separating comprises lifting the workpiece from the polishing surface.  
     
     
         16 . The polishing method as recited in  claim 15 , wherein said lifting comprises reducing a lifting speed of the workpiece until the workpiece has substantially been separated from the polishing surface.