WAFER STAGE WITH MAGNETIC BEARINGS

摘要

A high accuracy stage (1) supported in six degrees of freedom by electromagnetic bearings. Movements in the horizontal plane of the stage are supported by variable reluctance actuators which are mounted between the high accuracy stage (1) and a coarse stage (18) so as not to distort the high accuracy stage (1) during movements thereof. The high accuracy stage is supported in three vertical degrees of freedom by electromagnetic actuator devices which are preferably voice coil motors (12, 14) extending between the coarse stage (18) and the high accuracy stage (1). Additionally, dead weight supports are provided between the coarse stage (18) and the high accuracy stage (1) for vertically supporting the dead weight of the high accuracy stage (1). The dead weight supports are preferably air bellows (20).