Abstract: Transport apparatus for semiconductor wafers which have been subject to chemical mechanical polishing (CMP). The risk of malfunction of an articulated arm fitted with a vacuum chuck can be reduced in a number of different ways. The end effector can be constructed so that it can be easily removed from the arm for cleaning and can be easily replaced in the desired position without the need for adjustment. The arm can include one or more catch chambers into which materials drawn into the vacuum chuck will be deposited, but which will not interrupt the vacuum. The near end of the vacuum passage can be coupled to a source of a cleaning fluid, so that the cleaning fluid can be passed outwards through the vacuum passage to flush out materials drawn into the vacuum passage through the chuck.