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

Claim 15:
16. A method of forming a semiconductor wafer, the method comprising:
placing a wafer in a retaining ring of a polishing head, the retaining ring comprising three or more concentric sub-rings, wherein a difference in Shore D hardness between adjacent sub-rings is greater than 5, and wherein the adjacent sub-rings are joined, wherein the polishing head comprises a flexible membrane comprising a plurality of zones, the zones being concentric and having circular shapes, wherein a difference in Shore D hardness between an outermost sub-ring of the retaining ring and an innermost sub-ring of the retaining ring is greater than 30; and
polishing the wafer by bringing the wafer into contact with a polishing pad.