Patent ID: 11865666
Assignee: TAIWAN SEMICONDUCTOR MANUFACTURING COMPANY LTD.
Field: Machine tools (Mechanical engineering)
Classification: CPC B | IPC B

Claim 7:
8. A method of forming a semiconductor wafer, the method comprising:
placing a wafer in a polishing head, the polishing head comprising:
a retaining ring comprising:
a first ring comprising polyphenylene sulfide (PPS) or polyetheretherketone (PEEK);
a second ring within the first ring, the second ring defining the wafer holding region to hold the wafer, the second ring having a second hardness less than a first hardness of the first ring, the second ring comprising polyurethane, polyester, polyether, or polycarbonate; and
a third ring surrounding the first ring, the third ring having a third hardness greater than the first hardness and the third hardness is greater than the second hardness by more than 30 on a Shore D scale, wherein a first top surface of the first ring is level with a second top surface of the second ring and a third top surface of the third ring; and

a flexible membrane having a plurality of sealed chambers, the flexible membrane having a diameter less than a diameter of the wafer holding region; and

polishing the wafer by bringing the wafer into contact with a polishing pad.