Carrier head for a chemical mechanical polishing apparatus

Abstract

A chemical mechanical polishing (CMP) device carrier head ( 54 ) utilizing a pressure pack ( 58 ) for transferring a polishing force (D) to a wafer ( 15 ) being polished. The pressure pack may include a silicon gel material ( 60 ) encapsulated within a sealed urethane casing ( 62 ). The pressure pack provides a desired fluid coupling in the polishing force load path, allowing the carrier head to function as a front side floating reference polishing apparatus. The pressure pack may include a plurality of casings ( 70, 72 ) defining a plurality of chambers ( 66, 68 ) in order to affect the distribution of pressure across an abutting pressure plate ( 56, 65 ).

We claim as our invention:  
     
         1 . A carrier head for a chemical mechanical polishing apparatus comprising: 
 a frame adapted for connection to a drive apparatus;    a pressure plate adapted for contact with a wafer; and    a pressure pack disposed between the frame and the pressure plate for transferring a force there between.    
     
     
         2 . The carrier head of  claim 1 , wherein the pressure pack comprises a gelatinous material encapsulated within a sealed casing.  
     
     
         3 . The carrier head of  claim 1 , wherein the pressure pack comprises a fluid encapsulated within a sealed urethane casing.  
     
     
         4 . The carrier head of  claim 3 , wherein the gelatinous material comprises silicone.  
     
     
         5 . The carrier head of  claim 1 , wherein the pressure pack comprises a plurality of chambers.  
     
     
         6 . The carrier head of  claim 5 , wherein a first chamber comprises central portion of the pressure pack and a second chamber comprises a perimeter portion of the pressure pack.  
     
     
         7 . The carrier head of  claim 5 , wherein a first of the plurality of chambers is filled with a fluid at a first pressure and a second of the plurality of chambers is filled with a fluid at a second pressure different than the first pressure.  
     
     
         8 . The carrier head of  claim 5 , wherein a first of the plurality of chambers is filled with a first material and a second of the plurality of chambers is filled with a second material different than the first material.  
     
     
         9 . The carrier head of  claim 8 , wherein the viscosity of the first material is different than the viscosity of the second material.  
     
     
         10 . The carrier head of  claim 5 , wherein the pressure plate comprises a plurality of sections corresponding to the plurality of chambers.  
     
     
         11 . The carrier head of  claim 5 , wherein the pressure pack comprises a first material forming a first casing and a second material forming a second casing.  
     
     
         12 . The carrier head of  claim 1 , wherein the pressure pack comprises a fluid material encapsulated within a first sealed casing, and a second sealed casing encapsulating the first casing.  
     
     
         13 . A wafer polishing apparatus comprising: 
 a platen having a polishing pad affixed to a surface thereof, a wafer carrier head for holding a wafer to be polished and for abutting a surface of the wafer against the polishing pad;    a driving mechanism for polishing the surface of the wafer by moving the wafer carrier head with respect to the platen;    wherein the wafer carrier head further comprises:    a pressure plate adapted for urging the surface of the wafer against the polishing pad;    a frame for applying a force against the pressure plate; and    a pressure pack disposed between the frame and the pressure plate for transferring the force there between.    
     
     
         14 . The wafer polishing apparatus of  claim 13 , wherein the pressure pack comprises a fluid encapsulated within a sealed urethane casing.  
     
     
         15 . The wafer polishing apparatus of  claim 13 , wherein the pressure pack comprises a gelatinous material encapsulated within a sealed casing.  
     
     
         16 . The wafer polishing apparatus of  claim 15 , wherein the gelatinous material comprises silicone.  
     
     
         17 . The wafer polishing apparatus of  claim 13 , wherein the pressure pack comprises a plurality of chambers.  
     
     
         18 . The wafer polishing apparatus of  claim 17 , wherein a first chamber comprises a central portion of the pressure pack and a second chamber comprises a perimeter portion of the pressure pack.  
     
     
         19 . The wafer polishing apparatus of  claim 17 , wherein a first of the plurality of chambers is filled with a fluid at a first pressure and a second of the plurality of chambers is filled with a fluid at a second pressure different than the first pressure.  
     
     
         20 . The wafer polishing apparatus of  claim 17 , wherein a first of the plurality of chambers is filled with a first material and a second of the plurality of chambers is filled with a second material different than the first material.  
     
     
         21 . The wafer polishing apparatus of  claim 20 , wherein the viscosity of the first material is different than the viscosity of the second material.  
     
     
         22 . The wafer polishing apparatus of  claim 17 , wherein the pressure pack comprises a first material forming a first casing and a second material forming a second casing.  
     
     
         23 . The wafer polishing apparatus of  claim 13 , wherein the pressure pack comprises a fluid material encapsulated within a first sealed casing, and a second sealed casing encapsulating the first casing.  
     
     
         24 . A method of modifying a back side reference polishing apparatus to function as a floating reference polishing device, the back side polishing apparatus having a polishing pad affixed to a platen, a wafer carrier for holding a wafer to be polished against the polishing pad, a driving mechanism for polishing the wafer by moving the wafer carrier with respect to the platen, the wafer carrier further including a carrier head frame disposed against a pressure plate for urging the wafer against the polishing pad, the method comprising: 
 removing the pressure plate; and    replacing the pressure plate with a replacement pressure plate and a pressure pack, the pressure pack being disposed between the replacement pressure plate and the carrier head frame for transferring a force there between for urging the wafer against the polishing pad.    
     
     
         25 . The method of  claim 24 , further comprising providing the pressure pack to have a gelatinous material encapsulated within a sealed casing.  
     
     
         26 . The method of  claim 24 , further comprising providing the pressure pack to have a plurality of chambers.  
     
     
         27 . The method of  claim 24 , further comprising providing the pressure pack to have a fluid material encapsulated within a plurality of casings.  
     
     
         28 . A chemical mechanical polishing apparatus adapted for applying a polishing force to urge a substrate against a polishing pad, wherein the improvement comprises a pressure pack disposed in a load path of the polishing force.  
     
     
         29 . The chemical mechanical polishing apparatus of  claim 28 , wherein the pressure pack further comprises a gelatinous material encapsulated within a sealed casing.  
     
     
         30 . The chemical mechanical polishing apparatus of  claim 28 , wherein the pressure pack further comprises a plurality of chambers.  
     
     
         31 . The chemical mechanical polishing apparatus of  claim 28 , wherein the pressure pack comprises a fluid material encapsulated within a plurality of casings.