| 摘要 |
PROBLEM TO BE SOLVED: To stabilize a focus control in a highly precise manner by a method in which a moving means is controlled based on the output of a light-receiving element on which a reflected light is introduced from a mask and a photosensitive substrate and the beam width of the luminous flux with which the mask and the photosensitive substrate are illuminated. SOLUTION: An optical beams L1A and L1B are made to irradiate on a mask 5 and a photosensitive substrate 6, these reflected lights are introduced in parallel on the light-receiving surface 13A of a detector 13. On the other hand, the interval between the pulses, corresponding to the reflected light outputted from the detector 13, and the width of the pulses are detected. The driving mechanism of a substrate stage is controlled in such a manner that the photosensitive surface 6A of a photosensitive substrate 6 is positioned on the focul position of a projection optical system based on the interval between pulses obtained at that time. As a result, the erronous control of the driving mechanism of the substrate stage can be prevented, and a stabilized focus control can be conducted in a highly precise manner. |
