| 摘要 |
<P>PROBLEM TO BE SOLVED: To perform two-dimensional driving of a movable body continuously even upon occurrence of a fault in the measuring instrument system by switching servo control by an encoder system to servo control by an interferometer system. <P>SOLUTION: Positional information in the moving plane of a wafer stage WST is measured using an encoder system, e. g. an X head 66<SB>1</SB>and Y heads 67<SB>3</SB>and 68<SB>2</SB>, and drive control of the wafer stage is performed based on the measurements. At the same time, positional information of the wafer stage is measured using an interferometer system, e. g. an X interferometer 127 and a Y interferometer 16. When a fault is detected in the encoder system or the wafer stage deviates from the measurement region of the encoder system, switching is made to drive control based on the measurements of the interferometer system. Consequently, drive control of the wafer stage can be performed continuously over the entire stroke region even upon occurrence of a fault in the encoder system. <P>COPYRIGHT: (C)2009,JPO&INPIT |
