| 摘要 |
PROBLEM TO BE SOLVED: To measure highly accurately overlay displacements between patterns, by correcting without altering the optical system of a measuring apparatus the measurement errors caused by the fact that the right and left of the sectional structure of an overlay measurement mark are asymmetric. SOLUTION: A stage 10 for supporting thereon a semiconductor wafer 11 is made inclinable by a stage inclination drive portion 18 to change the projecting angle of the illumination light on overlay measurement marks on the wafer 11. The projecting angles are fixed to a Z-direction (0 deg.) and±θdeg., and mark pictures are picked up by a CCD camera 14 to obtain the overlay displacements between patterns by processing the obtained picture signals through a picture processing computing portion 15. At this time, the shadow components generated in the step portions of the marks included in the mark pictures of±θdeg. are utilized to correct the measurement errors caused by the fact that the right and left of the sectional structure of the mark are asymmetric. |
