| 摘要 |
PURPOSE:To enable precisely alignment of a wafer with a mask with a simple configuration by detecting target patterns on a wafer and a mask from a photoreceptor provided at a slit frame for scanning reciprocatingly and rectilinearly. CONSTITUTION:When a specimen on X-axis stage 7 and Y-axis stage 8 is irradiated through a translucent mirror 13 from an illumination light source lamp 10, the reflected light of the target mark of the mask 3 and the wafer 6 is divided through a translucent mirror 13 via a translucent mirror 14 into two. The light reflected on the mirror 14 is introduced into an X-axis image rotator 18 to cause the target mark to be rotated in a plane vertical to the optical axis to form an image on a slit 22. On the other hand, the light passed through the mirror 14 is introduced through a Y-axis image rotator 19 to form an image on the slit. The images on the slits are detected by photoreceptors 24, 25 provided on the slit frame 23. As the frame 23 scans, the detected level variations are instantaneously obtained of the photoreceptors 24, 25 by a strain gauge 28 to obtain the deviations in X and Y directions of the target pattern so as to automatically align the wafer with the mask. |
