<p>A substrate polishing apparatus and method are described. A base includes at least one movable platen to engage a polishing pad. At least one carrier head assembly presses a substrate against the polishing pad substantially within a polishing area during a polishing operation. A polishing solution dispenser applies a polishing solution to the polishing pad substantially within the polishing area during the polishing operation. A polishing solution retaining mechanism is attached to one of the base or the carrier head assembly. The retaining mechanism engages a top surface of the polishing pad and retains the polishing solution substantially within the polishing area during the polishing operation. Some implementations may reduce polishing solution consumption and allow for increased angular velocity.</p>
