| 摘要 |
<p>Positional information of a movement plane of a wafer stage is measured using an encoder system such as, for example, an X head and a Y head, and the wafer stage is controlled based on the measurement results. At the same time, positional information of the wafer stage is measured using an interferometer system such as, for example, an X interferometer and a Y interferometer. When abnormality of the encoder system is detected or when the wafer stage moves off from a measurement area of the encoder system, drive control is switched to a drive control based on the measurement results of the interferometer system. Accordingly, drive control of the wafer stage can be performed continuously in the entire stroke area, even at the time when abnormality occurs in the encoder system.</p> |
