| 摘要 |
PURPOSE:To more accurately detect the two-dimensional position of an object to be detected, by correcting the astigmatism generated in an optical system for position detection. CONSTITUTION:The pattern of a reticle R is exposed on a wafer W via a projection aligner. In an alignment system 4 on the side surface of the projection aligner, the alignment light from a wafer mark WM on the wafer W forms an image of the wafer mark WM on a focal plate 11, through an objective 7, a beam splitter 6, a negative cylindrical lens 8, and a positive cylindrical lens 9. The image on the focal plate 11 is picked up by image sensing elements 13M and 13S, via an imagery lens 11. By changing the absolute rotation angles of the cylirxdrical lenses 8, 9 or the relative rotation angle or the interval, the astigmatism generated by the objective 7 and the beam spitter 6 us cancelled. |
