| 摘要 |
<p>PURPOSE:To detect a wafer alignment pattern with high contrast and perform an accurate alignment by irradiating the latticelike alignment pattern of a wafer with an illumination light having a narrow spectral width and good directivity to detect it by a focusing optical system, and controlling a space filter at an optimum position. CONSTITUTION:A latticelike wafer alignment pattern 21 on a wafer 19 is irradiated through a lens 2, a galvanomirror 3, a polarizing beam splitter 8, the metal face of a mask alignment pattern 17 and a projecting lens 18 with a laser illumination light (S-polarization) having a narrow spectral width. A high order-diffracted light scattered from the pattern 21 is propagated reversely through the optical path of the light, altered to P-polarized light by a 1/4 wavelength plate 6, and focused through a space filter 11 by a cylindrical lens 12 on a linear sensor 13. In this case, a control system 14 controls the position of the filter 11 through a driving system 11a in a direction Z, always extracts only the scattered light from the pattern 12 to detects it with high contrast, and performs an accurate alignment.</p> |
