| 摘要 |
PURPOSE:To measure the best focus position of a projection optical system, only by performing exposure without changing the focus position of a photosensitive substrate. CONSTITUTION:A first pattern 24 and a second pattern 25 on a mask 17A are irradiated with exposure lights IL1 and IL2, respectively, which have different inclination angles of principal rays to the optical axis of a projection optical system 19. Thus the images of the patterns 24, 25 are projected on the exposure surface on a surface 27. The interval D2 between the images of the patterns 24 and 25 is measured. The defocus amount DELTAF is obtained by using the relation between the interval D2 and the defocus amount DELTAF which relation is previously obtained. |
