| 摘要 |
A controller uses two Z heads, which are positioned above a reflection surface installed on the ±X ends of the upper surface of a wafer table, to measure the height and tilt of the wafer table. The Z head to be used is switched according to XY positions of the wafer table. On the switching of the heads, the controller applies a coordinate linkage method to set an initial value of the Z head which is to be newly used. Accordingly, although the Z head to be used is sequentially switched according the XY position of the wafer table, measurement results of the height and the tilt of the wafer table are stored before and after the switching, and it becomes possible to drive the wafer table with high precision. |
