US Patent 9193027 Retainer ring

A retainer ring is provided for use in conjunction with Chemical Mechanical Polishing apparatus which polishing is used to polish a substrate. Particularly, the retainer ring includes an inner surface defining a retainer area, an outer surface, a front surface extending between the inner and outer surface, the front surface being in contact with the polishing pad during polishing and a transition region between the outer surface and the front surface. A CMP apparatus which includes at least a ring having the above features is also provided for.