A reinforcement ring is for placement in a carrier head to abut an inner surface of a perimeter portion of a flexible membrane. The reinforcement ring includes a substantially vertical cylindrical portion, a first flange projecting inwardly from the bottom of the cylindrical portion, and a second flange projecting outwardly from a bottom of the cylindrical portion. The second flange projects downwardly at a non-zero angle from vertical.
展开▼
