| 摘要 |
PURPOSE:To raise the contrast of a pattern detecting signal as well as to improve the accuracy in pattern positioning by using monochromatic light having desired wave length so as to efficiently utilize equal-thickness interference fringe produced at photoresist on a wafer. CONSTITUTION:A reticle 2 is arranged under a condenser lens 1 for pattern exposure and a wafer 4 mounted with a reducing lens 3 is arranged at predetermined interval under said reticle 2. Then, a pattern of the wafer 4 focused into a image on the reticle 2 is photoelectrically transduced by being projected upon a photomultiplier 9 through a magnifying optical system 5 and a slit 6. Meanwhile in case that the exposure wave length at that time is insufficient to obtain enough reflection for detection, green light is used to transduce photoelectrically a magnified image focused on the reticle 2 through the magnifying optical system 5 and the slit 6 by adding said magnified image upon another photomultiplier 9'. Thus an optical filter arranged in the optical system is changed and wave length is specified to detect a pattern image on a wafer. |
