| 摘要 |
PURPOSE:To simplify a detection system and to facilitate the detection by introducing reflected or secondary electrons into a flat plate electrode having fluorescent substance disposed between a photoelectric mask and a substrate to be exposed to convert them into fluorescent light, and detecting the amount of the light from the exterior of a space between the mask and the snbstrate. CONSTITUTION:The intensity change of reflected or secondary electrons RE generated when the stepwise mark 21 of a wafer 20 face is irradiated with a photoelectron stream PE obtained by radiating a positioning pattern 13 formed on a photoelectric mask 10 face with a light beam UV is converted by a fluorescent substance 51 on a flat plate electrode 50 face into a fluorescent light FL, and the intensity change of the fluorescent light is further detected by a photoelectric multiplier 52 disposed outside a space surrounded by the mask 10 and the wafer 20. Thus, when the electrons RE are converted to the light FL, the fluorescent light is photon, and not charged particles like the reflected or secondary electrons. Accordingly, the light can be freely produced out of the space without receiving the forces of electric and magnetic fields. Therefore, it is detected by the multiplier 52 disposed out of the space to easily detect it by a normal detection system.
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