Multiple polishing heads with cross-zone pressure element distributions for cmp

Abstract

Various embodiments of the present disclosure are directed towards a chemical mechanical polishing (CMP) system including a first CMP head and a second CMP head. The first CMP head is configured to retain a workpiece and comprises a first plurality of pressure elements disposed across a first pressure control plate. The second CMP head is configured to retain the workpiece. The second CMP head comprises a second plurality of pressure elements disposed across a second pressure control plate. A distribution of the first plurality of pressure elements across the first pressure control plate is different from a distribution of the second plurality of pressure elements across the second pressure control plate.

What is claimed is: 
     
         1 . A chemical mechanical polishing (CMP) system comprising:
 a first CMP head configured to retain a workpiece, wherein the first CMP head comprises a first plurality of pressure elements disposed across a first pressure control plate; and   a second CMP head configured to retain the workpiece, wherein the second CMP head comprises a second plurality of pressure elements disposed across a second pressure control plate, wherein a distribution of the first plurality of pressure elements across the first pressure control plate is different from a distribution of the second plurality of pressure elements across the second pressure control plate.   
     
     
         2 . The CMP system of  claim 1 , wherein the first plurality of pressure elements are respectively concentric with respect to one another and with respect to a center of the first pressure control plate, wherein the second plurality of pressure elements are respectively concentric with respect to one another and with respect to a center of the second pressure control plate. 
     
     
         3 . The CMP system of  claim 1 , wherein a number of pressure elements within the first plurality of pressure elements is equal to a number of pressure elements within the second plurality of pressure elements. 
     
     
         4 . The CMP system of  claim 1 , wherein a number of pressure elements within the first plurality of pressure elements is less than a number of pressure elements within the second plurality of pressure elements. 
     
     
         5 . The CMP system of  claim 1 , wherein a diameter of the first pressure control plate is equal to a diameter of the second pressure control plate. 
     
     
         6 . The CMP system of  claim 1 , wherein a diameter of an innermost pressure element of the first plurality of pressure elements is less than a diameter of an innermost pressure element of the second plurality of pressure elements. 
     
     
         7 . The CMP system of  claim 1 , wherein widths of the first plurality of pressure elements are respectively different from widths of the second plurality of pressure elements. 
     
     
         8 . The CMP system of  claim 1 , further comprising:
 a third CMP head configured to retain the workpiece, wherein the third CMP head comprises a third plurality of pressure elements disposed across a third pressure control plate, wherein a distribution of the third plurality of pressure elements across the third pressure control plate is different from the distribution of the first plurality of pressure elements and the distribution of the second plurality of pressure elements.   
     
     
         9 . The CMP system of  claim 1 , wherein the first and second plurality of pressure elements respectively comprise a concentric chamber configured to provide independent pressures to corresponding regions of the workpiece. 
     
     
         10 . A polishing system for performing a polishing process comprising:
 a first polishing apparatus comprising a first platen and a first chemical mechanical polishing (CMP) head, wherein the first CMP head is configured to perform a first CMP process on a to-be-polished surface of a workpiece, wherein the first CMP head comprises a first plurality of concentric pressure elements and a first annular retaining ring laterally enclosing the first plurality of concentric pressure elements;   a second polishing apparatus comprising a second platen and a second CMP head, wherein the second CMP head is configured to perform a second CMP process on the to-be-polished surface of the workpiece, wherein the second CMP head comprises a second plurality of concentric pressure elements and a second annular ring laterally enclosing the second plurality of concentric pressure elements, wherein widths of the second plurality of concentric pressure elements are respectively different from widths of the first plurality of concentric pressure elements;   a surface measurement apparatus positioned on the first platen and the second platen, wherein the surface measurement apparatus is configured to measure a planarity of the to-be-polished surface of the workpiece in real time while performing the first and second CMP processes, wherein pressures exerted by the second plurality of concentric pressure elements during the second CMP process are based on the measured planarity of the to-be-polished surface after the first CMP process; and   a transport apparatus configured to transport the workpiece between the first polishing apparatus and the second polishing apparatus.   
     
     
         11 . The polishing system of  claim 10 , further comprising:
 a third polishing apparatus comprising a third platen and a third CMP head, wherein the third CMP head is configured to perform a third CMP process on the to-be-polished surface of the workpiece, wherein the third CMP head comprises a third plurality of concentric pressure elements and a third annular ring laterally enclosing the third plurality of concentric pressure elements, wherein widths of the third plurality of concentric pressure are respectively different from widths of the first and second plurality of concentric pressure elements.   
     
     
         12 . The polishing system of  claim 11 , wherein a width of an innermost concentric pressure element of the first CMP head is greater than widths of concentric pressure elements of the first CMP head that laterally surround the innermost concentric pressure element of the first CMP head, and wherein a width of an innermost concentric pressure element of the third CMP head is less than the width of the innermost concentric pressure element of the first CMP head. 
     
     
         13 . The polishing system of  claim 12 , wherein a width of a second innermost concentric pressure element of the third CMP head is greater than the width of the innermost concentric pressure element of the third CMP head. 
     
     
         14 . The polishing system of  claim 11 , wherein a number of concentric pressure elements within the first plurality of concentric pressure elements is less than a number of concentric pressure elements within the second plurality of concentric pressure elements, and a number of concentric pressure elements within the third plurality of concentric pressure elements is greater than the number of concentric pressure elements in the second plurality of concentric pressure elements. 
     
     
         15 . The polishing system of  claim 11 , further comprising:
 a forth polishing apparatus comprising a fourth platen and a fourth CMP head, wherein the fourth CMP head is configured to perform a fourth CMP process on the to-be-polished surface of the workpiece, wherein the fourth CMP head comprises a fourth plurality of concentric pressure elements and a fourth annular ring laterally enclosing the fourth plurality of concentric pressure elements, wherein widths of the fourth plurality of concentric pressure elements are respectively different from widths of the first, second, and third plurality of concentric pressure elements.   
     
     
         16 . The polishing system of  claim 15 , wherein the first, second, third, and fourth plurality of concentric pressure elements respectively comprise a same number of concentric pressure elements. 
     
     
         17 . A method for chemical mechanical polishing (CMP) of a workpiece, the method comprising:
 performing a first CMP process on a front-side surface of the workpiece with a first CMP head having a first distribution of a first plurality of pressure elements across the first CMP head;   measuring a planarity of the front-side surface of the workpiece; and   performing a second CMP process on the front-side surface of the workpiece with a second CMP head having a second distribution of a second plurality of pressure elements across the second CMP head, wherein a pressure exerted by the second plurality of pressure elements is based on the measured planarity of the front-side surface of the workpiece, and wherein the second distribution is different from the first distribution.   
     
     
         18 . The method of  claim 17 , wherein a width of an innermost pressure element of the first CMP head is less than a width of an innermost pressure element of the second CMP head. 
     
     
         19 . The method of  claim 17 , further comprising:
 performing a third CMP process on the front-side surface of the workpiece with a third CMP head having a third distribution of a third plurality of pressure elements across the third CMP head, wherein the third distribution is different from the first distribution and the second distribution.   
     
     
         20 . The method of  claim 19 , further comprising:
 performing a fourth CMP process on the front-side surface of the workpiece with a fourth CMP head having a fourth distribution of a fourth plurality of pressure elements across the fourth CMP head, wherein the fourth distribution is different from the first distribution, the second distribution, and the third distribution.