Polishing platen of chemical mechanical polishing apparatus and planarization method using the same

Abstract

A polishing platen of a chemical mechanical polishing apparatus and a planarization method using the same are disclosed. The polishing platen is formed of a first plate connected to a second plate. By independently controlling a thermal expansion of the first and second plates, a shape of an upper surface of the platen can be controlled and selectively altered. This allows a more precise polishing process and formation of a more uniform wafer. In one embodiment, the first and second plates, each have a different thermal expansion coefficient.

What is claimed is:  
     
         1 . A polishing platen of a chemical mechanical polishing apparatus, which apparatus moves a semiconductor wafer relative to said polishing platen to accomplish a chemical mechanical polishing process on the wafer, said polishing platen comprising: 
 an upper metallic plate having a first thermal expansion coefficient; and    a lower metallic plate having a second thermal expansion coefficient, different than said first thermal expansion coefficient.    
     
     
         2 . The polishing platen of  claim 1 , further comprising: 
 at least one of a heating line and a cooling line embedded in at least one of said upper metallic plate and said lower metallic plate.    
     
     
         3 . The polishing platen of  claim 1 , further comprising: 
 a heating and cooling line embedded in at least one of said upper metallic plate and said lower metallic plate.    
     
     
         4 . The polishing platen of  claim 1 , further comprising: 
 a first heating and cooling line embedded in said upper metallic plate; and    a second heating and cooling line embedded in said lower metallic plate.    
     
     
         5 . The polishing platen of  claim 1 , wherein said first thermal expansion coefficient is greater than said second thermal expansion coefficient.  
     
     
         6 . The polishing platen of  claim 1 , wherein said first thermal expansion coefficient is less than said second thermal expansion coefficient.  
     
     
         7 . The polishing platen of  claim 1 , wherein said upper metallic plate is formed of either stainless steel or aluminum.  
     
     
         8 . The polishing platen of  claim 7 , wherein said lower metallic plate is formed of cast iron.  
     
     
         9 . The polishing platen of  claim 1 , wherein said lower metallic plate is formed of either stainless steel or aluminum.  
     
     
         10 . The polishing platen of  claim 9 , wherein said upper metallic plate is formed of cast iron.  
     
     
         11 . The polishing platen of  claim 1 , wherein said upper metallic plate and said lower metallic plate are attached by an adhesive or a screw.  
     
     
         12 . A polishing apparatus comprising: 
 a platen;    a pad supported on said platen;    a holder for positioning a semiconductor wafer adjacent to said pad; and    a drive connected to at least one of said platen and said holder causing relative movement between said holder and said pad to polish the semiconductor wafer, wherein said platen includes: 
 a first plate having a first thermal expansion coefficient; and  
 a second plate having a second thermal expansion coefficient, different than said first thermal expansion coefficient.  
   
     
     
         13 . The polishing apparatus of  claim 12 , further comprising: 
 at least one of a heating line and a cooling line embedded in at least one of said first plate and said second plate.    
     
     
         14 . The polishing apparatus of  claim 12 , further comprising: 
 a first heating or cooling line embedded in said first plate; and    a second heating or cooling line embedded in said second plate.    
     
     
         15 . The polishing apparatus of  claim 12 , wherein: 
 said first plate includes a first side and an opposite, second side;    said second plate includes a first side and an opposite, second side;    said first side of said second plate is attached to said second side of said first plate;    said first plate is formed of a metal having said first thermal expansion coefficient; and    said second plate is formed of a metal having said second thermal expansion coefficient.    
     
     
         16 . The polishing apparatus of  claim 15 , wherein said first surface of said first plate assumes a convex or concave shaped depending upon a temperature of said first and second plates.  
     
     
         17 . The polishing apparatus of  claim 15 , wherein one of said first and second plates is formed of stainless steel or aluminum, and the other of said first and second plates is formed of cast iron.  
     
     
         18 . The polishing apparatus of  claim 15 , wherein said first surface of said second plate is attached to said second surface of said first plate by an adhesive or a screw.  
     
     
         19 . A polishing apparatus comprising: 
 a platen;    a pad supported by said platen;    a holder for positioning a semiconductor wafer adjacent to said pad; and    a drive connected to at least one of said platen and said holder causing relative movement between said holder and said pad to polish the semiconductor wafer, wherein said platen includes: 
 a first plate having a first surface and an opposite, second surface;  
 a second plate having a first surface and an opposite, second surface, wherein said first surface of said second plate is attached to said second surface of said first plate;  
 a first heating or cooling line controlling a temperature of said first plate; and  
 a second heating or cooling line controlling a temperature of said second plate, to thereby cause said first surface of said first plate to assume a convex or concave configuration based upon a temperature differential between said first and second plates.  
   
     
     
         20 . The polishing apparatus of  claim 19 , wherein one of said first and second plates is formed of stainless steel or aluminum, and the other of said first and second plates is formed of cast iron.  
     
     
         21 . The polishing apparatus of  claim 19 , wherein said first surface of said second plate is attached to said second surface of said first plate by an adhesive or a screw.  
     
     
         22 . A planarization method of a chemical mechanical polishing apparatus comprising: 
 providing a platen formed by the attachment of a first plate and a second plate;    providing a pad on the platen;    engaging a wafer to a surface of the pad;    causing relative movement between the wafer and the surface of the pad to polish the wafer; and    controlling a temperature of at least one of the first and second plates to cause platen, and hence the surface of the pad, to adjust to a desire shape to influence the polishing of the wafer.    
     
     
         23 . The method according to  claim 22 , further comprising: 
 applying a slurry on the surface of the pad.    
     
     
         24 . The method according to  claim 22 , wherein a temperature of the first plate is elevated relative to a temperature of the second plate to enhance polishing of a central portion of the wafer.  
     
     
         25 . The method according to  claim 22 , wherein a temperature of the second plate is elevated relative to a temperature of the first plate to enhance polishing of edge portions of the wafer.