Independent edge control for CMP carriers

Abstract

A wafer carrier for controlling the edge effect during chemical mechanical planarization. A first bladder is disposed within the retaining ring to control the height of the retaining ring relative to the bottom surface of the wafer carrier. A second bladder is disposed within the carrier such that if the pressure in the bladder is regulated, the amount of force on the edge of the wafer changes. If a polishing process would cause material near the edge of the wafer to be removed at a higher rate than from the rest of the wafer, then the pressure is regulated within the bladder to reduce the force against the edge of the wafer. By reducing the force against the edge of the wafer, material is removed from the front side of the wafer at a uniform rate.

1 - 9 . (canceled)  
   
   
       10 . A wafer carrier comprising a carrier housing, a mounting plate and a retaining ring with an inner diameter extending below the mounting plate to form a cylindrical recess sized to receive a wafer, said wafer carrier further comprising: 
 a membrane extending across the inner diameter of the retaining ring; and    a shim ring disposed above the membrane near an area corresponding to an edge of the wafer when the wafer is disposed within the inner diameter of the retaining ring.    
   
   
       11 . The wafer carrier of  claim 10  further comprising an annular edge control bladder disposed above the shim ring.  
   
   
       12 . The wafer carrier of claim  1  wherein the shim ring is sized and dimensioned to adjust the height of the bladder relative to the membrane.  
   
   
       13 . The wafer carrier of  claim 10 , wherein the shim ring is sized and dimensioned to adjust the radial distance of the bladder relative to the vertical axis of the carrier.  
   
   
       14 . The wafer carrier of  claim 10  wherein the shim ring is sized and dimensioned to attain a predetermined pressure range near the area corresponding to the edge of the wafer.  
   
   
       15 . The wafer carrier of  claim 10  wherein the membrane further comprises a membrane projection, said membrane extension disposed within an annular space provided in the carrier housing.  
   
   
       16 . A wafer carrier comprising a carrier housing, a mounting plate and a retaining ring with an inner diameter extending below the mounting plate to form a cylindrical recess sized to receive a wafer, said wafer carrier further comprising: 
 a shim ring disposed within the inner diameter of the retaining ring near an area corresponding to an edge of the wafer when the wafer is disposed within the inner diameter of the retaining ring.    
   
   
       17 . The wafer carrier of  claim 16  wherein the shim ring is sized and dimensioned to adjust the height of the bladder relative to the membrane.  
   
   
       18 . The wafer carrier of  claim 16  wherein the shim ring is sized and dimensioned to adjust the radial distance of the bladder relative to the vertical axis of the carrier.  
   
   
       19 . The wafer carrier of  claim 16  wherein the shim ring is sized and dimensioned to attain a predetermined pressure range near the area corresponding to the edge of the wafer.  
   
   
       20 . The wafer carrier of  claim 16  wherein the shim ring is further disposed within an annular groove within the mounting plate.  
   
   
       21 . The wafer carrier of  claim 20  wherein the shim ring comprises an annular groove.  
   
   
       22 . The wafer carrier of  claim 21  further comprising an O-ring disposed within the annular groove of the mounting plate.  
   
   
       23 . The wafer carrier of  claim 16  wherein a sealed space is disposed between the shim ring and the mounting plate.