Patent ID: 8556684

Claim:
A retaining ring for chemical mechanical polishing comprising: a substantially annular retaining ring having an upper portion, a lower portion, an inner portion and an outer portion; wherein said upper portion is configured with a plurality of grooves wherein each of said grooves is elliptical and said lower portion is adapted to contact a polishing pad and a semiconductor wafer during polishing; and inserts substantially the same shape as said grooves fixably insertable into said grooves, wherein an opening in said inserts allows a fastener to be passed therethrough to secure said retaining ring to a carrier head, and wherein said openings do not penetrate said lower portion; said insert having a main body portion and a raised portion, said main body portion having a top side, a bottom side, and a main body edge; wherein an opening is located along an axis through said main body portion such that said main body edge is configured elliptically around said axis.