SLANT POSITION DETECTING DEVICE UTILIZING FRESNEL DIFFRACTION BASED ON MULTIPLE-WAVE LENGTH COHERENT LIGHT

摘要

PURPOSE:To simplify a detecting mark by providing the alignment mark comprising a linear Fresnel zone plate on each body, and constituting a lighting device so that the linear Fresnel zone plate is lit at the same time with the lights having a plurality of wavelengths. CONSTITUTION:Two LFZP, which are alignment marks 28 for wafers 15 are provided on both sides of a linear Fresnel zone plate (LFZP herein, which is an alignment mark 27 for an X-ray mask 14 at the center. The LFZP 28 is observed through a transparent window 22 of the X-ray mask 14 arranged at the upper side. Therefore, the illuminating lights with a plurality of coherent lights can be utilized. The defect of the image focusing in the slant direction is overcome by inclining the objective lens having the single focal point and performing the slant detection. In the alignment device, wherein the Fresnel diffraction wit the multiple-wavelength coherent light is utilized, the constitution of the detecting mark becomes simple, and the image, which is equivalent to the vertical image focusing, is obtained.