US Patent 7238090 Polishing apparatus having a trough

Methods and apparatus for chemical mechanical polishing are described. In one embodiment, an apparatus includes a table top and a transfer station and multiple polishing stations are mounted on the table top. The apparatus further includes multiple washing stations, where each washing station is located between either two polishing stations or between a polishing station and a transfer station. Multiple carrier heads are supported by a support member that is rotatable about an axis. The transfer station and the multiple polishing stations are arranged at approximately equal angular intervals about the axis.