Patent attributes
A polishing device includes a polishing pad for polishing a wafer and a polishing head for holding the wafer. The polishing head has a retainer ring for retaining the wafer in the in-plane direction of the wafer, a membrane sheet for pressing the wafer against the polishing pad, and a head body for supporting the retainer ring and the membrane sheet. The retainer ring has a subordinate retainer member having a ring portion and a plurality of fins extending from the ring portion to retain the peripheral surface of the wafer. The subordinate retainer member has a thickness equal to the thickness of the wafer. The membrane sheet has a diameter larger than the wafer, and presses the wafer and the vicinity of the inner edge of the subordinate retainer member.
