| 摘要 |
PURPOSE:To expose a wafer of a large diameter to far ultraviolet rays and, at the same time, improve the resolution of the wafer, by concentrically arranging the convex mirror and concave mirror having a prescribed radius of an image forming optical system which forms a slit image on a mask and setting the most suitable image forming position outside of the optical axis. CONSTITUTION:A luminous flux from a spot-like far ultraviolet ray source 20 forms a circular-arc-like luminous flux on a circular-arc-like slit 11 after the luminous flux is reflected by a concave mirror 35 and is made incident to an image forming optical system 13'. The image forming optical system 13' is composed of a convex mirror 26 and concave mirror having a radius of curvature which is twice as large as the radius of curvature of the convex mirror 26, both of which are arranged concentrically, as in the case of an unmagnification optical system 1. The circular-arc-like slit image forms its image on a mask 7 without aberration through a mirror 28, concave mirror 25, convex mirror 26, and mirror 27 and the image of the mask 7 is formed on a wafer 8 through the unmagnification optical system 1. Therefore, the wafer having a large diameter can be exposed of far ultraviolet rays and, at the same time, its resolution can be improved. |
