Retainer ring and wafer polishing system including the retainer ring

A retainer ring comprising:

• a coupling block configured to be coupled to a polishing head;
• and
• a mold block coupled to the coupling block to support a wafer positioned on a polishing pad and to contact the polishing pad,
• wherein the mold block comprises:
• a body coupled to the coupling block;
• a plurality of pad contacts disposed over an upper side of the body and configured to contact the polishing pad;
• a plurality of slurry passages formed between the plurality of pad contacts and configured to allow a slurry to flow from an outer circumferential side of the body to an inner circumferential side of the body;
• and
• a plurality of slurry guides respectively disposed over outer sides of the pad contacts located on a rear side, with respect to a rotational direction of the polishing head, of the pad contacts,
• wherein each slurry guide intersects a respective slurry passage, and the slurry passage has a width that increases in a direction opposite to the rotational direction of the polishing head by the slurry guide.