| 摘要 |
PURPOSE:To improve an alignment accuracy, by arranging at least two movable reflecting faces in front of an objective optical system so that the optical axis of an alignment microscope is kept always vertical to the plane of a mask. CONSTITUTION:A first objective lens system 18 having an optical axis 17 parallel to the patterned face of a reticle 1 is positioned such that it does not intercept exposing light 2 to the reticle 1, namely such that it does not intercept the light in the maximum exposure region including the circuit pattern on the reticle 1. The optical axis 17 is bent by a mirror 6 to the direction away from the reticle and then bent by a mirror 5 so as to constitute an optical axis 15 vertical to the reticle 1. The mirrors 5 and 6 are fixed to an osillating arm 7 supported rotatably around a shaft 8. Thereby, the observing optical axis can be kept always vertical to the plane of a mask indenpendently from an accuracy of positioning the optical path bending means. In this manner, an improved alignment accuracy can be obtained. |
