Flexible bending member for a workpiece carrier apparatus

Abstract

A flexible membrane for a wafer polishing apparatus has a central contact portion, an annular bending element connected to the central contact portion and an outer annual ring connected to the annular bending element. The membrane is configured to apply uniform pressure to a workpiece during polishing.

I claim:  
     
         1 . A flexible membrane for a wafer polishing apparatus comprising: 
 a) a central contact portion;    b) an annular bending element connected to said central contact portion; and    c) an outer annular ring connected to said annular bending element; wherein said membrane is configured to apply uniform pressure to a workpiece during polishing.    
     
     
         2 . The flexible membrane of  claim 1 , wherein said annular bending element is integrally connected to said outer annular ring.  
     
     
         3 . The flexible membrane of  claim 1 , wherein said annular bending element is integrally connected said central contact portion.  
     
     
         4 . The flexible membrane of  claim 1 , wherein said membrane comprises at least one of EPDM rubber, natural rubber and SBR rubber.  
     
     
         5 . The flexible membrane of  claim 1 , wherein said annular bending element has a first thickness and said outer annular ring has a second thickness and said first thickness is approximately equal to said second thickness.  
     
     
         6 . The flexible membrane of  claim 1 , wherein said annular bending element has a first thickness and said outer annular ring has a second thickness and said second thickness is greater than said first thickness.  
     
     
         7 . The flexible membrane of  claim 1 , wherein said annular bending element has a first thickness and said central contact portion has a third thickness and wherein said first thickness is approximately half of the third thickness.  
     
     
         8 . A workpiece carrier head for a chemical mechanical polishing apparatus comprising: 
 a) a carrier plate;    b) a flexible membrane having an outer peripheral edge, an annular bending element positioned proximate to said outer peripheral edge, and a central contact portion disposed proximate to said annular bending element, wherein said membrane is connected to said carrier plate at said outer peripheral edge, thereby forming a cavity between said central contact portion of said flexible membrane and said carrier plate; and    c) an annular retaining ring disposed adjacent said outer peripheral edge of said flexible membrane.    
     
     
         9 . The workpiece carrier head of  claim 8 , wherein said annular bending element of said flexible membrane has a first thickness and said outer peripheral edge of said flexible membrane has a second thickness, said first thickness being approximately equal to said second thickness.  
     
     
         10 . The workpiece carrier head of  claim 8 , wherein said annular bending element of said flexible membrane has a first thickness and said outer peripheral edge of said flexible membrane has a second thickness, said second thickness being greater than said first thickness.  
     
     
         11 . The workpiece carrier head of  claim 8 , wherein said annular bending element of said flexible membrane has a first thickness and said central contact portion has a second thickness, said first thickness being approximately half said second thickness.  
     
     
         12 . The workpiece carrier head of  claim 8 , wherein said carrier plate comprises at least one fluid conduit by which a source of a vacuum and a source of a pressurized fluid are alternatively connected to the cavity.  
     
     
         13 . The workpiece carrier head of  claim 8 , wherein said outer peripheral edge of said membrane has a first width and said retaining ring has a second width and wherein said first width and said second width are approximately equal.  
     
     
         14 . The workpiece carrier head of  claim 8 , wherein said outer peripheral edge of said membrane has a first width and said retaining ring has a second width and wherein said first width is less than said second width.  
     
     
         15 . The workpiece carrier head of  claim 8 , wherein said outer peripheral edge of said membrane has a first width and said retaining ring has a second width and wherein said first width is greater than said second width.  
     
     
         16 . The workpiece carrier head of  claim 8 , wherein said membrane comprises EPDM rubber.  
     
     
         17 . The workpiece carrier head of  claim 8 , wherein said outer peripheral edge of said flexible membrane is integrally connected to said annular bending element.  
     
     
         18 . The workpiece carrier head of  claim 8 , wherein said central contact portion is integrally connected to said annular bending element.  
     
     
         19 . The workpiece carrier element of  claim 12 , wherein said central contact portion of said flexible membrane comprises a plurality of apertures configured so that when said source of a vacuum is connected to said cavity, a workpiece is drawn against said flexible membrane.  
     
     
         20 . A method of polishing a workpiece comprising the steps of: 
 a) loading a workpiece into a workpiece carrier head comprising: 
 i) a carrier plate;  
 ii) a circular flexible membrane having an outer peripheral edge, an annular bending element positioned proximate to said outer peripheral edge and a central contact portion disposed proximate to said annular bending element, wherein said membrane is connected to said carrier plate at said outer peripheral edge, thereby forming a cavity between said central contact portion of said flexible membrane and said carrier plate, and  
 iii) an annular retaining ring disposed adjacent said peripheral edge of said flexible membrane;  
   b) moving the workpiece carrier head until the workpiece is adjacent a polishing pad;    c) pressurizing said cavity such that said flexible membrane bends at said annular bending element and said central contact portion applies pressure to said workpiece and urges said workpiece against said polishing pad; and    d) causing relative motion between said workpiece and said polishing pad.    
     
     
         21 . The method of  claim 20 , wherein said loading step further comprises loading said workpiece into said workpiece carrier head, wherein said workpiece carrier head has a plurality of recesses.  
     
     
         22 . The method of  claim 21 , wherein said step of loading further comprises effecting a vacuum in said cavity so that said central contact portion of said flexible membrane adjacent said recesses are drawn into said recesses, thereby effecting a vacuum between said central contact portion and said workpiece.  
     
     
         23 . The method of  claim 20 , wherein said loading step further comprises loading said workpiece into said workpiece carrier head, wherein said central contact portion has a plurality of apertures.  
     
     
         24 . The method of  claim 23 , wherein said loading step further comprises effecting a vacuum in said cavity and within said apertures such that said workpiece is drawn against said central contact portion of said flexible membrane.