Some embodiments relate to a method of using a polishing system. In this method, a wafer is secured in a carrier head. The carrier head includes a housing, which includes a retaining ring recess, enclosing the wafer. A retaining ring is positioned in the retaining ring recess. The retaining ring surrounds the wafer, and has a hardness ranging from about 5 shore A to about 80 shore D. The wafer is pressed against a polishing pad, and at least one of the carrier head or the polishing pad is moved relative to the other.