| 摘要 |
PURPOSE:To position a mask and a wafer relatively and extremely accurately by directly detecting the projected image of a mark formed on the mask by an optoelectric element set up to a stage. CONSTITUTION:Light beams emitted from an illumination system 4 for exposure uniformly illuminate the whole surface of a mask 5, and an image to be transferred to a circuit pattern formed to the lower surface of the mask 5 is imaged on the wafer 7 through a projecting lens 6. On the other hand, laser luminous flux from a light source 11 is beam-expanded 12, deflected in a surface parallel with a paper surface by a vibrating mirror 13, focused by a focusing lens 15 through a beam splitter 14, reflected to the lower side of a dichroic mirror 10 through a reflecting mirror 17, and imaged on the surface of the wafer through the projecting lens 6. The image on the wafer is detected by the optoelectric element 28. Optical path lengths up to the entrance pupil of the lens 6 are each made differ from the mask 5 and the lens 15, and the mask 5 and a laser light spot are imaged on the same plane. |
