Carrier head with flexible membrane

Abstract

A carrier head for chemical mechanical polishing of a substrate has a flexible membrane extending beneath a base to define a chamber. The flexible membrane provides a substrate receiving surface, and can be configured so that a pressure profile applied to a substrate is substantially insensitive to retaining ring wear.

What is claimed is:  
     
         1 . A carrier head for chemical mechanical polishing of a substrate, comprising: 
 a base;    a retaining ring to surround a substrate on a substrate receiving surface; and    a flexible membrane extending beneath the base to define a chamber and provide the substrate receiving surface and the flexible membrane configured so that a pressure profile applied to a substrate is substantially insensitive to retaining ring wear.    
     
     
         2 . The carrier head of  claim 1 , wherein the flexible membrane further includes a central portion having a substrate receiving portion and a flexure portion having a first end coupled to the base such that an effective load area is reduced as a distance between the first end of the flexure portion and the central portion decreases.  
     
     
         3 . A carrier head for chemical mechanical polishing of a substrate, comprising: 
 a base; and    a flexible membrane extending beneath the base to define a chamber and provide a substrate receiving surface, the flexible membrane including a central portion with the substrate receiving portion and a flexure portion having a first end coupled to the base.    
     
     
         4 . The carrier head of  claim 3 , wherein the flexure portion is directly connected to the base.  
     
     
         5 . The carrier head of  claim 3 , wherein the flexure portion is indirectly connected to the base.  
     
     
         6 . The carrier head of  claim 3 , wherein the flexible membrane is configured such that an effective load area is reduced as a distance between the first end of the flexure portion and the central portion decreases.  
     
     
         7 . The carrier head of  claim 3 , wherein the flexible membrane includes a perimeter portion at an edge of the center portion.  
     
     
         8 . The carrier head of  claim 7 , wherein the perimeter portion is less subject to deformation than the central portion.  
     
     
         9 . The carrier head of  claim 7 , wherein the perimeter portion is coupled to an internal membrane clamp.  
     
     
         10 . The carrier head of  claim 9 , wherein the perimeter portion is coupled to a support piece.  
     
     
         11 . The carrier head of  claim 7 , wherein the flexible membrane includes an extension portion connecting the perimeter portion and a second end of the flexure portion.  
     
     
         12 . The carrier head of  claim 1   1 , wherein the extension portion pivots when pulled by the flexure portion.  
     
     
         13 . The carrier head of  claim 11 , wherein the extension pivots so that an effective load area on the perimeter portion effective is reduced as the extension is pulled.  
     
     
         14 . The carrier head of  claim 11 , wherein the first end of the flexure portion is radially inward of the second end of the flexure portion, and the extension is pulled inwardly.  
     
     
         15 . The carrier head of  claim 11 , further comprising a retaining ring to surround a substrate on the substrate receiving surface.  
     
     
         16 . The carrier head of  claim 15 , wherein the extension portion moves so that a pressure profile applied to a substrate is substantially insensitive to retaining ring wear.  
     
     
         17 . The carrier head of  claim 15 , wherein the extension pivots so that an effective load area on the perimeter portion effective is reduced and at least a portion of an increased the load at the edge of the membrane caused by retaining ring wear is offset.  
     
     
         18 . The carrier head of  claim 3 , wherein the flexible membrane includes two flexure portions, each having a first end coupled to the base.  
     
     
         19 . The carrier head of  claim 18 , wherein the flexible membrane includes a perimeter portion coupled to an internal membrane clamp, the internal membrane clamp located immediately adjacent to a lower of the two flexures and configured to allow free movement of the lower of the two flexures.  
     
     
         20 . The carrier head of  claim 3 , wherein the two flexures define two chambers of pressure in the carrier head.  
     
     
         21 . A flexible membrane for use with a carrier head of a substrate chemical mechanical polishing apparatus, the membrane comprising: 
 a central portion including a substrate receiving portion; and    a flexure portion having a first end to be coupled to a base of the carrier head, wherein the flexure portion is configured so that a pressure profile applied to a substrate by the central portion is substantially insensitive to relative vertical movement of the vertical position of the central portion relative to the first end of the flexure portion.    
     
     
         22 . The flexible membrane of  claim 21 , further comprising: 
 a perimeter portion connecting a second end of the flexure portion to the central portion.    
     
     
         23 . The flexible membrane of  claim 22 , wherein the perimeter portion is less subject to deformation than the central portion.  
     
     
         24 . The flexible membrane of  claim 22 , wherein the perimeter portion is coupled to an internal membrane clamp.  
     
     
         25 . The flexible membrane of  claim 22 , further comprising: 
 an extension portion connecting the perimeter portion to the second end of the flexure portion.    
     
     
         26 . The flexible membrane of  claim 25 , wherein the extension portion pivots when pulled by the flexure portion.  
     
     
         27 . The flexible membrane of  claim 21 , wherein the flexure portion includes two flexure portions.  
     
     
         28 . The flexible membrane of  claim 27 , further comprising a perimeter portion coupled to an internal membrane clamp, and connecting a second end of each flexure portion to the central portion, the internal membrane clamp located immediately adjacent to a lower of the two flexures and configured to allow free movement of the lower of the two flexures.  
     
     
         29 . A method of polishing a substrate comprising: 
 mounting a substrate on a carrier head of a chemical mechanical polishing apparatus so that a first side the substrate is adjacent to the carrier head, the carrier head including a base portion, a retaining ring and a flexible membrane including a central portion providing a mounting surface for the substrate; and    polishing the substrate using a polishing pad contacting a second side of the substrate on a side opposite from the first side of the substrate,    wherein the flexible membrane moves during polishing so that a pressure profile applied to a substrate during polishing is substantially insensitive to ring wear.    
     
     
         30 . A method of operation of a flexure portion of a flexible membrane, the flexure portion connected between a carrier head and a perimeter portion of the flexible membrane, the method comprising: 
 maintaining a position of a flexure portion that is substantially parallel to a substrate mounted on a central portion of a flexible membrane while a retaining ring of a carrier head maintains its original dimensions, the flexure portion connected at a first end to the carrier head;    pivoting an extension portion toward the retaining ring as the polishing progresses, the extension portion connecting a second end of the flexure portion to a perimeter portion of the flexible membrane; and    pivoting the extension portion toward the flexure as the retaining ring wears down.