| 摘要 |
A workpiece alignment apparatus which comprises a workpiece alignment unit onto which a workpiece is passed. The workpiece alignment unit comprises a fluid distribution support 113 which has an apertured or porous upper surface, which provides a supporting fluid cushion on which a workpiece W is supported and aligned. The support surface has at least two regions or compartments 116a, 116b from which fluids of different pressure and/or flow rate are delivered, thereby generating a differential pressure across regions of the support surface. Having two regions allows the wafer workpiece to be lifted higher above one region compared to another. To aid alignment two positioning stops 118a, 118b are used. The differential pressure can be created by altering the pressure supplied to the regions or by altering the thickness or porosity of the porous, air-permeable support. |
