Abstract: A work piece carrier head for the chemical mechanical planarization of a work piece includes a backing plate that is capable of being extended beyond the lower surface of the carrier head during a work piece loading operation. The exposed lateral surface of the backing plate in the extended position provides a reference surface to enable a work piece handling wand to align itself prior to loading the work piece into the carrier head. The work piece handling wand is configured to grip a work piece between a concave cradle and a moveable gripping finger. A work piece held by the wand can be centered relative to the backing plate prior to loading the work piece into the work piece carrier head by registering the wand to the exposed lateral surface of the extended backing plate.