| 摘要 |
PURPOSE:To enable to correct fluctuations in the focal point of light rays for exposure during the exposing operation by a method wherein a probe luminous flux is made to incide in the luminous flux for exposure, the focusing position of the probe light is detected and the position of the image formation surface of the luminous flux for exposure is detected. CONSTITUTION:Main light rays EL for exposure are irradiated through a reticle R and the pattern of the reticle R is projected on a wafer. A non-photosensitive laser luminous flux LA is irradiated by a laser alignment system (LSA)14. The LA is reflected by mirrors 14a and 14b and is made to incide in the entrance pupil 8a of a projection lens 8. A reference marking plate 30 is provided on a wafer holder 19. A lattice-type mark is formed on the plate 30. The LA is irradiated on the plate 30 to generate a diffracted light. The diffracted light is returned to the LSA. By this way, the size of the spotlight to be focused on the plate 30 is detected and the position of the image formation surface of the main light rays EL is detected. |
