Retainer ring, polish apparatus, and polish method

A retainer ring configured to be attachable, at a first side thereof, to a polish head of a polish apparatus configured to polish a polish object by depressing the polish object against a polish pad, the retainer ring configured to depress the polish pad at a second side thereof, the retainer ring comprising:

• a contact surface configured to contact the polish pad,
• the contact surface configured to apply depressing force on the polish pad, the depressing force being directed from a polish head side and being applied so as to be centered on an imaginary circle of pressure center having a radius falling substantially in a middle of an inner radius of the retainer ring and an outer radius of the retainer ring,
• two or more concentric grooves being provided on the contact surface so that a count of the concentric grooves is greater in a second region outside the circle of pressure center than in a first region inside the circle of pressure center, and
• an area of the contact surface being greater in the first region inside the circle of pressure center than in the second region outside the circle of pressure center.