A workpiece processing apparatus allowing in situ cleaning of metal deposited formed on the extraction plate and in the plasma chamber is disclosed. The apparatus includes an extraction plate having an extraction aperture through which the sputtering material is passed. The apparatus also includes a sealed volume disposed within the plasma chamber which is in communication with a cleaning aperture on the extraction plate. The sealed volume is in communication with a cleaning gas, which is excited by the plasma in the plasma chamber, and can be used to clean the exterior surface of the extraction plate. The feed gas used in the plasma chamber can be selected from a sputtering species and the cleaning gas. Since the volume in the sealed volume is separated from the rest of the plasma chamber, the cleaning of the extraction plate and the cleaning of the plasma chamber may be performed independently.