Device and method for improved cmp process with cmp head

Abstract

A chemical mechanical planarization (CMP) head holds a wafer during a CMP process. The CMP head includes a blend of a Lewis acid polymer and a Lewis base polymer. The blend of the Lewis acid polymer and the Lewis base polymer renders the CMP head anti-electrostatic. This helps ensure that an electrostatic charge does not build up around the bottom of the CMP head during a CMP process. This helps ensure that charged debris particles do not accumulate at the CMP head.

1 . A method, comprising:
 rotating a chemical mechanical planarization (CMP) pad;   supplying a slurry onto the CMP pad;   holding a wafer with a CMP head including a retaining ring that is a blend of a Lewis acid polymer and Lewis base polymer surrounding a lateral edge of the wafer; and   placing the wafer in contact with the CMP pad.   
     
     
         2 . The method of  claim 1 , wherein a molar ratio of the Lewis acid polymer to the Lewis base polymer of the retaining ring is between 0.2 and 0.8. 
     
     
         3 . The method of  claim 2 , wherein the molar ratio of the Lewis acid polymer to the Lewis base polymer of the retaining ring is between 0.4 and 0.6. 
     
     
         4 . The method of  claim 1 , wherein a bottom surface of the retaining ring is in contact with the slurry. 
     
     
         5 . The method of  claim 1 , wherein the Lewis base polymer includes one or more of nylon, PVAc, PLA, PMMA, and PPS. 
     
     
         6 . The method of  claim 1 , wherein the Lewis acid polymer includes one or more of PVDF, PVC, PS, PVDC, and PEEK. 
     
     
         7 . The method of  claim 1 , wherein the retaining ring is anti-electrostatic. 
     
     
         8 . The method of  claim 1 , wherein the slurry includes an abrasive including silica or cerium oxide, wherein the retaining ring resists developing an electrostatic charge from contact with the abrasive. 
     
     
         9 . The method of  claim 1 , further comprising performing a multistep CMP process on the wafer while the retaining ring surrounds the wafer. 
     
     
         10 . The method of  claim 9 , wherein the multistep CMP process includes a first step with a first removal rate and a second step with a second removal rate smaller than the first removal rate. 
     
     
         11 . A device, comprising:
 a retaining ring for a chemical mechanical planarization (CMP) head, the retaining ring including:
 an annular interior surface; 
 a bottom surface configured to contact a CMP pad; 
 a coupler configured to fixedly couple the retaining ring to the CMP head, wherein the retaining ring includes a Lewis acid polymer and a Lewis base polymer blended together. 
   
     
     
         12 . The device of  claim 11 , wherein the retaining ring includes a metal portion coupled to the blend of the Lewis Acid polymer and the Lewis base polymer. 
     
     
         13 . The device of  claim 12 , wherein a molar ratio of the Lewis acid polymer to the Lewis base polymer is between 0.2 and 0.8. 
     
     
         14 . The device of  claim 11 , further comprising grooves in the bottom surface of the retaining ring. 
     
     
         15 . The device of  claim 11 , wherein the Lewis base polymer includes one or more of nylon, PVAc, PLA, PMMA, and PPS. 
     
     
         16 . The device of  claim 11 , wherein the Lewis acid polymer includes one or more of PVDF, PVC, PS, PVDC, and PEEK. 
     
     
         17 . The device of  claim 11 , wherein the retaining ring includes a metal core surrounded by the blend of the Lewis base polymer and the Lewis acid polymer. 
     
     
         18 . A method, comprising:
 forming a layer on a wafer with a thin film deposition process;   loading the wafer onto a chemical mechanical planarization (CMP) head, wherein a lateral surface of the wafer is surrounded by a retaining ring when the wafer is loaded onto the CMP head, wherein the retaining ring is a blend of a Lewis acid polymer and Lewis base polymer; and   at least partially removing the layer by performing a CMP process on the wafer while the wafer is loaded onto the CMP head.   
     
     
         19 . The method of  claim 18 , wherein the layer is a dielectric material formed in a trench to isolate two gate electrodes formed on the wafer. 
     
     
         20 . The method of  claim 18 , wherein the CMP process includes a first stage and a second stage having a lower removal rate than a removal rate of the first stage.