| 摘要 |
<P>PROBLEM TO BE SOLVED: To stably and highly-accurately measure positional information of a moving body, moving substantially along a predetermined plane, in a direction perpendicular to the predetermined plane. <P>SOLUTION: On the +X and -X sides of a projection unit PU, a plurality of Z heads 76, 74 are arranged in parallel to the X-axis, by a predetermined distance WD half or less than half the effective width of the Y scale so that two Z heads each constantly form a pair and face a pair of Y scales (opposite surface) on a wafer stage. Of the pair of heads consisting of two Z heads which simultaneously face the Y scale, measurement values of a priority head is used, and when abnormality occurs in the measurement values of the priority head due to malfunction of the head, measurement values of the other head is used, and the positional information of the wafer stage in at least the Z-axis direction can be stably and highly-accurately measured. <P>COPYRIGHT: (C)2009,JPO&INPIT |
