| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide an alignment system improved and capable of capturing an alignment position by using a single alignment mark and/or adjusting asymmetric alignment marks. <P>SOLUTION: In the alignment system, a self-reference interferometer to form two superposed relatively rotating images of alignment markers is used. A detector detects the intensity on a pupil surface where Fourier transformations of the images are made to interfere. A position information is obtained from a phase difference between diffraction orders of the two images indicated as intensity variations in the interfered orders. The asymmetry is also measurable by measuring intensities at two positions on either one side of the diffraction orders. <P>COPYRIGHT: (C)2008,JPO&INPIT |
