| 主权项 |
1. A carrier head, comprising:
a base; a substrate mounting surface; a retaining ring secured to the base, the retaining ring having a bottom surface for contacting a polishing pad during polishing and a top surface for contacting the base, the top surface being substantially flat from an inner diameter of the retaining ring to an outer diameter of the retaining ring; and a plurality of stacked shims located between the base and the retaining ring, wherein the plurality of stacked shims includes a first shim and a second shim, and the first shim is thicker than the second shim, wherein each shim of the plurality of stacked shims has a same inner diameter and outer diameter as the retaining ring. |
