Patent ID: 7819723

Claim:
A retainer ring for holding an outer circumferential portion of an object to be polished, comprising: a first annular portion for surrounding said outer circumferential portion of said object, said first annular portion having a first outer rim portion, a first inner rim portion, and an upper surface extending radially from the first inner rim portion to the first outer rim portion, and a second annular portion provided on said first upper surface of said first annular portion, said second annular portion having a second outer rim portion, a second inner rim portion, and a lower surface extending radially from the second inner rim portion to the second outer rim portion, wherein said second annular portion is fixed to said first annular portion by a mechanical joining, wherein an entirety of said upper surface of said first annular portion is in contact with said lower surface of said second annular portion, and wherein said mechanical joining includes a first thread provided in a surface of said first outer rim portion of said first annular portion, and a second projecting portion protruding from said second outer rim portion of said second annular portion and provided with a second thread configured to mate with said first thread.