CMP Groove Depth and Conditioning Disk Monitoring

Abstract

Some embodiments relate to a chemical mechanical polishing (CMP) system. The CMP system includes a polishing pad having a polishing surface, and a wafer carrier to retain a wafer proximate to the polishing surface during polishing. A motor assembly rotates the polishing pad and concurrently rotates the wafer during polishing of the wafer. A conditioning disk has a conditioning surface that is in frictional engagement with the polishing surface during polishing. A torque measurement element measures a torque exerted by the motor assembly during polishing. A condition surface analyzer determines a surface condition of the conditioning surface or the polishing surface based on the measured torque. Other systems and methods are also disclosed.

What is claimed is: 
     
         1 . A chemical mechanical polishing (CMP) system, comprising:
 a polishing pad having a polishing surface;   a wafer carrier to retain a wafer proximate to the polishing surface during polishing;   a motor assembly to rotate the polishing pad about a polishing pad axis and concurrently rotate the wafer about a wafer axis during polishing of the wafer;   a conditioning disk having a conditioning surface, wherein the conditioning surface is in frictional engagement with the polishing surface during polishing;   a torque measurement element to measure a torque exerted by the motor assembly during polishing; and   a condition surface analyzer to determine a surface condition of the conditioning surface or the polishing surface based on the measured torque.   
     
     
         2 . The CMP system of  claim 1 , further comprising:
 a feedback path to adjust a CMP process parameter in real-time during polishing of the wafer based on the surface condition determined by the condition surface analyzer.   
     
     
         3 . The CMP system of  claim 1 , wherein the polishing pad includes a plurality of grooves in the polishing surface, the CMP system further comprising:
 a depth measurement element to measure groove depths of the respective grooves during polishing of the wafer.   
     
     
         4 . The CMP system of  claim 3 , wherein the depth measurement element comprises an acoustic transducer to measure the groove depths while a liquid is present on the polishing surface. 
     
     
         5 . The CMP system of  claim 3 , wherein the depth measurement element is arranged on a scan arm to diametrically traverse over the polishing pad to measure the groove depths of the respective grooves. 
     
     
         6 . The CMP system of  claim 1 , wherein the motor assembly rotates the polishing pad about a platen axis at a first angular velocity and rotates the wafer about a wafer carrier axis at an second angular velocity. 
     
     
         7 . The CMP system of  claim 6 , further comprising:
 a feedback path to adjust the first angular velocity or the second angular velocity based on the surface condition determined by the condition surface analyzer.   
     
     
         8 . The CMP system of  claim 1 , wherein the conditioning surface has a hardness that is greater than a hardness of the polishing surface. 
     
     
         9 . The CMP system of  claim 8 , wherein the conditioning surface is a diamond encrusted surface. 
     
     
         10 . The CMP system of  claim 2 , further comprising:
 a slurry dispenser to dispense an abrasive slurry onto the polishing surface;   wherein the feedback path is configured to adjust a slurry composition or slurry temperature based on the surface condition determined by the condition surface analyzer.   
     
     
         11 . The CMP system of  claim 2 , wherein wafer carrier includes a plurality of concentric and variable down-force elements adapted to apply respective down-forces with respect to the polishing pad to concentric wafer regions;
 wherein the feedback path is configured to adjust the respective down-forces based on the surface condition determined by the condition surface analyzer.   
     
     
         12 . A chemical mechanical polishing (CMP) system for polishing a wafer, comprising:
 a platen arranged to rotate about a platen axis;   a polishing pad arranged over the platen and arranged to rotate about the platen axis coincidentally with the platen, the polishing pad including a polishing surface having one or more grooves disposed therein;   a depth measurement element to measure groove depths of respective grooves in real-time during polishing of the wafer; and   a feedback path to adjust a CMP parameter in real-time based on the respective measured groove depths.   
     
     
         13 . The CMP system of  claim 12 , wherein the depth measurement element comprises an acoustic transducer to measure the groove depths while a liquid is present on the polishing surface. 
     
     
         14 . The CMP system of  claim 13 , wherein the liquid comprises slurry or deionized water. 
     
     
         15 . The CMP system of  claim 12 , wherein the depth measurement element is arranged on a scan arm to diametrically traverse over the polishing pad to measure the groove depths of the respective grooves. 
     
     
         16 . A method of chemical mechanical polishing (CMP), comprising:
 setting a set of CMP process parameters to be used for planarizing one or more wafers;   providing an abrasive slurry on a polishing surface of a CMP station;   placing a conditioning surface in frictional engagement with the polishing surface to condition the polishing surface;   placing a to-be-polished wafer surface proximate to the conditioned polishing surface;   polishing the to-be-polished wafer surface while employing the set of CMP process parameters; and   during polishing of the wafer, measuring a surface condition of the polishing surface or conditioning surface.   
     
     
         17 . The method of  claim 16 , further comprising:
 adjusting a CMP process parameter during polishing based on the measured surface condition.   
     
     
         18 . The method of  claim 16 , wherein the surface condition is measured by measuring a torque of a motor assembly used to move the polishing surface or wafer. 
     
     
         19 . The method of  claim 16 , wherein polishing surface includes a number of grooves, and wherein the surface condition is measured by measuring depths of the respective grooves during polishing. 
     
     
         20 . The method of  claim 19 , wherein the depths of the respective grooves are measured using an acoustic transducer.