Platen design for improving edge performance in CMP applications

摘要

An invention is disclosed for improving edge performance in a chemical mechanical polishing process is disclosed. The system includes a wafer head disposed above a wafer, where the wafer head includes a first active retaining ring capable of extension and retraction. Below the wafer head is a polishing belt, and disposed below the polishing belt is a platen having a second active retaining ring capable of extension and retraction. During operation the first active retaining ring and the second active retaining ring can be controlled to provide positional control for the polishing belt, thus adjusting and controlling the removal rate at the edge of the wafer.