| 摘要 |
<P>PROBLEM TO BE SOLVED: To stably and highly-accurately measure the position of a moving body, moving in a two-dimensional plane. <P>SOLUTION: On the +X and -X sides of a projection unit PU, a plurality of Y heads 65, 64 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 heads each constantly form a pair and face a pair of Y scales on a wafer stage. Similarly, on the +Y and -Y sides of the projection unit PU, a plurality of X heads 66 are arranged in parallel to the Y-axis by the distance WD, so that two heads each constantly form a pair and face a pair of X scales. Of the pair of heads consisting of two heads which simultaneously face the scale, measurement values of a priority head are 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. Then, by using the measurement values of the two pairs of Y heads and the pair of X heads, a position of the wafer stage within a two-dimensional plane is stably and highly-accurately measured. <P>COPYRIGHT: (C)2009,JPO&INPIT |
