POLISHING HEAD AND EDGE CONTROL RING THEREOF, AND METHOD OF INCREASING POLISHING RATE AT WAFER EDGE

摘要

A polishing head used for CMP is described, including a retaining ring that is for engaging with a wafer, a membrane and an edge control ring. The membrane includes a bottom part for engaging with the wafer, and a lip part contiguous with the bottom part. The edge control ring is disposed between the retaining ring and the membrane, including a bottom part that has an abutting surface. The abutting surface of the edge control ring contacts with the external surface of the lip part of the membrane when the membrane is not inflated.