Chemical mechanical planarization (CMP) system and method for determining an endpoint in a CMP operation

The present invention relates generally to semiconductor fabrication and, more particularly, to a system and method for determining an endpoint in the chemical mechanical planarization of thin films, particularly metal films comprised of copper. In a method for determining an endpoint in a chemical mechanical planarization (CMP) operation, the concentration of an oxidizing agent in the slurry byproduct generated during the CMP operation is monitored. The endpoint of the CMP operation is determined based on the concentration of the oxidizing agent in the slurry byproduct. The concentration of the oxidizing agent in the slurry byproduct may be monitored by diverting the slurry byproduct from a surface of a polishing pad, and measuring an optical property of the slurry byproduct diverted from the surface of the polishing pad. A CMP system configured to implement the method for determining an endpoint also is described.