Patent ID: 9694470
Date: 2017-07-04
CPC Classifications: B24B,Y10T

Claim:
1. A retaining ring, comprising: an annular lower portion of a first material, the lower portion having a lower surface to contact a polishing pad and an upper surface, wherein the upper surface of the lower portion includes an upwardly projecting step positioned along an inner diameter of the lower portion, wherein a remainder of the upper surface of the lower portion between the step and an outer diameter of the lower portion is flat, and wherein at the inner diameter of the lower portion a total height of the lower portion including the step and between the lower and upper surfaces is larger than a total height of the lower portion between the lower and upper surfaces at a location between the step and the outer diameter of the lower portion; an annular upper portion of a different second material, the upper portion having a lower surface and an upper surface, wherein the lower surface of the upper portion includes a recess positioned along an inner diameter of the upper portion and the step fits into the recess, and wherein a remainder of the lower surface of the upper portion between the recess and an outer diameter of the upper portion is flat; and a bonding layer securing the lower portion to the upper portion.