| 摘要 |
PURPOSE:To make it possible to monitor the amount of exposure of a wafer accurately and thereby to execute accurate control of the amount of exposure at all times by a method wherein a change in the retardation of an exposure light generated by an image rotating prism is reduced so that the state of polarization of the exposure light entering a beam splitter may not change so much when the image rotating prism rotates during exposure. CONSTITUTION:A linearly polarized laser light emitted from a laser 1 passes through a 1/4 wave plate 2 and an image rotating prism 3 and enters an illuminating optical system 4. Since the 1/4 wave plate 2 is provided so that the plane of polarization of the laser light be changed from that of linear polarization to that of circular polarization, the state of polarization of the laser light entering a half mirror 5 dose not change so much in accordance with the rotation of the image rotating prism 3 and illuminance on the light-sensing surface of a light-sensing element of an integrating exposure meter 6 is fixed substantially. Accordingly, the ratio between the illuminance on the light sensing surface and that on a water 11 is always fixed, the quantity of the laser light reaching the wafer 11 can be monitored accurately by the integrating exposure meter 6, and the amount of exposure can always be controlled accurately on the occasion when each pattern region arranged on the wafer 11 is exposed. |
