Clamping retainer for chemical mechanical polishing

Abstract

A carrier head for chemical mechanical polishing includes a housing, a substrate mounting surface, and a retaining ring assembly. The retaining ring assembly includes an inner ring surrounding the substrate mounting surface and having an inner surface to retain the substrate below the substrate mounting surface, a first actuator to adjust a vertical load on the inner ring, an outer ring surrounding the inner ring, and a second actuator positioned between the inner ring and the outer ring. The inner ring has a plurality of slots that are formed in a lower surface and that extend from the inner surface to an outer surface of the inner ring to divide the inner ring into a plurality of arcuate segments suspended from an upper portion. The second actuator applies a radially inward pressure such that the plurality of arcuate segments flex inwardly relative to the upper portion.

What is claimed is: 
     
         1 . A carrier head for chemical mechanical polishing, comprising:
 a housing;   a substrate mounting surface; and   a retaining ring assembly including
 an inner ring surrounding the substrate mounting surface and having an inner surface to retain the substrate below the substrate mounting surface, the inner ring having a lower surface and a plurality of slots that are formed in the lower surface and that extend from the inner surface to an outer surface of the inner ring to divide the inner ring into a plurality of arcuate segments suspended from an upper portion, 
 an outer ring surrounding the inner ring, and 
 a first actuator positioned between the inner ring and the outer ring to apply a radially inward pressure such that the plurality of arcuate segments flex inwardly relative to the upper portion. 
   
     
     
         2 . The carrier head of  claim 1 , wherein the inner ring is independently vertically movable relative to the outer ring. 
     
     
         3 . The carrier head of  claim 2 , wherein the outer ring is vertically fixed to the housing. 
     
     
         4 . The carrier head of  claim 3 , wherein the inner ring is suspended from the housing by a second actuator. 
     
     
         5 . The carrier head of  claim 1 , wherein the inner ring is vertically fixed relative to the outer ring. 
     
     
         6 . The carrier head of  claim 5 , comprising a second actuator positioned between the housing and the inner ring and the outer ring to adjust a vertical position of the inner ring and the outer ring. 
     
     
         7 . The carrier head of  claim 6 , wherein the inner ring comprises a flange that extends between a top surface of the outer ring and the second actuator. 
     
     
         8 . The carrier head of  claim 6 , wherein the outer ring comprises a flange that extends between a top surface of the inner ring and the second actuator. 
     
     
         9 . The carrier head of  claim 1 , wherein the first actuator comprises a bladder. 
     
     
         10 . The carrier head of  claim 9 , wherein an inner surface of the outer ring has a first projection extending above the bladder. 
     
     
         11 . The carrier head of  claim 10 , wherein the inner surface of the outer ring has a second projection extending below the bladder. 
     
     
         12 . The carrier head of  claim 10 , wherein an outer surface of the inner ring has a second projection extending below the bladder. 
     
     
         13 . The carrier head of  claim 9 , wherein the bladder is positioned at least partially in a recess in an outer surface of the inner ring. 
     
     
         14 . The carrier head of  claim 1 , wherein an entirety of the inner ring is a first plastic. 
     
     
         15 . The carrier head of  claim 14 , wherein the outer ring comprises an lower portion and a upper portion that is more rigid than the lower portion. 
     
     
         16 . The carrier head of  claim 15 , wherein the lower portion of the outer ring is the first plastic. 
     
     
         17 . The carrier head of  claim 1 , wherein the slots are spaced at equal angular intervals around a center axis of the inner ring. 
     
     
         18 . The carrier head of  claim 1 , wherein each arcuate segment extends through an arc of 5-20° relative to the center of the inner ring. 
     
     
         19 . A method of polishing, comprising:
 bringing a substrate into contact with a polishing surface;   generating relative motion between the substrate and the polishing surface; and   applying a radially inward pressure to the substrate by pressing inwardly on an inner ring that has a plurality of slots that divide the inner ring into a plurality of arcuate segments suspended from an upper portion.   
     
     
         20 . The method of  claim 19 , comprising moving the inner ring independently vertically movable relative to an outer ring that surrounds the inner ring.