| 摘要 |
PURPOSE:To avoid the degradation in asymmetry of alignment marks and the degrada tion in an alignment accuracy by a method wherein only the alignment marks which are so provided as to have their longitudinal directions directed toward the center of a wafer are used. CONSTITUTION:X-direction alignment marks 3A whose longitudinal directions are directed toward the center of a wafer 7 are scanned by a He-Ne laser beam 2A whose spot has an oblong shape. The longer diameter of the spot of the laser beam 2A is shorter than the longitudinal length of the X-direction alignment mark 3A by about 1mum. The signal intensity of a diffracted an scattered light beam produced by scanning is varied and an X-direction position is calculated. Then, in order to obtain a Y- direction position, the X-direction alignment marks 3A are scanned several turns while the laser beam 2A is shifted by a certain interval at every turn. The signal intensity of a diffracted and scattered beam is varied and the position on an X-axis where the maximum peak value is detected is obtained to obtain the Y-direction position. An alignment correction value, expansion and contraction, a perpendicularity, a rotation and a position deviation can be obtained only by the information of the alignment marks whose longitudinal directions are directed toward the center of the wafer. |
