Real-time monitoring of retaining ring thickness and lifetime

Abstract

A method and apparatus for monitoring the condition of a surface of a retaining ring disposed on a carrier head in a polishing module is described. In one embodiment, a method for monitoring at least one surface of a retaining ring coupled to a carrier head is provided. The method includes moving the carrier head adjacent a sensor device disposed in a polishing module, transmitting energy from the sensor device toward the retaining ring, receiving energy reflected from the retaining ring, and determining a condition of the retaining ring based on the received energy.

1 . A method for monitoring at least one surface of a retaining ring coupled to a carrier head, the method comprising:
 moving the carrier head adjacent a sensor device disposed in a polishing module;   transmitting energy from the sensor device toward the retaining ring;   receiving energy reflected from the retaining ring; and   determining a condition of the retaining ring based on the received energy.   
     
     
         2 . The method of  claim 1 , wherein the transmitted and received energy is a sound wave. 
     
     
         3 . The method of  claim 1 , wherein the transmitted and received energy is an optical signal. 
     
     
         4 . The method of  claim 1 , wherein the transmitted and received energy is a magnetic field. 
     
     
         5 . The method of  claim 1 , wherein the energy is transmitted and received through a liquid. 
     
     
         6 . The method of  claim 1 , further comprising:
 moving the carrier head adjacent a load cup assembly disposed in the polishing module, the sensor device being disposed in a body of the load cup assembly.   
     
     
         7 . The method of  claim 6 , further comprising:
 actuating the sensor device within the load cup assembly as the retaining ring is in the line-of-sight of the sensor device.   
     
     
         8 . The method of  claim 7 , wherein the received energy is indicative of a thickness of the retaining ring. 
     
     
         9 . The method of  claim 1 , further comprising:
 transferring a substrate to the carrier head; and   urging the substrate toward a polishing surface of a polishing pad disposed in the polishing module to perform a polishing process on the substrate.   
     
     
         10 . The method of  claim 9 , wherein the received energy is indicative of a thickness of the retaining ring, the method further comprising:
 adjusting one or more parameters of the polishing process based on a thickness of the retaining ring.   
     
     
         11 . A method for monitoring at least one surface of a retaining ring coupled to a carrier head, the method comprising:
 moving the carrier head adjacent a load cup assembly disposed in a polishing module, the sensor device being disposed in a body of the load cup assembly;   transmitting energy from the sensor device toward a surface of the retaining ring as the retaining ring is in the line-of-sight of the sensor device;   receiving energy reflected from the surface; and   determining a thickness of the retaining ring based on the received energy.   
     
     
         12 . The method of  claim 11 , wherein the surface is a contact surface of the retaining ring. 
     
     
         13 . The method of  claim 11 , wherein the surface is a metallic surface disposed inside the retaining ring. 
     
     
         14 . The method of  claim 11 , wherein the surface is the bottom of a groove formed in the retaining ring. 
     
     
         15 . A method for monitoring at least one surface of a retaining ring coupled to a carrier head, the method comprising:
 moving the carrier head adjacent a load cup assembly disposed in a polishing module, the sensor device being disposed in a body of the load cup assembly;   rinsing the retaining ring;   transmitting energy from the sensor device toward a surface of the retaining ring as the retaining ring is in the line-of-sight of the sensor device;   receiving energy reflected from the surface; and   determining a thickness of the retaining ring based on the received energy.   
     
     
         16 . The method of  claim 15 , wherein the surface is a contact surface of the retaining ring. 
     
     
         17 . The method of  claim 15 , wherein the surface is a metallic surface disposed inside the retaining ring. 
     
     
         18 . The method of  claim 15 , wherein the surface is the bottom of a groove formed in the retaining ring. 
     
     
         19 . The method of  claim 15 , wherein the transmitted and received energy is a sound wave, an optical signal, an electrical signal, a magnetic field, or combinations thereof. 
     
     
         20 . The method of  claim 15 , wherein a contact surface of the retaining ring is contacting an active surface of the body of the load cup assembly when the energy is transmitted and received.