| 摘要 |
<p>PURPOSE:To accurately detect the position of a wafer mark even when the mark is coated with a photosensitive material or a film having a transmittance distribution characteristic which varies depending upon the wavelength. CONSTITUTION:A wafer mark 32X is irradiated with light emitted from an optical fiber 21 through a wavelength selecting filter plate 22, ND filter plate 23, collimator lens system 24, objective lens 30, etc., and reflected light from the mark 32X is guided to an index plate 34 through the objective lens 30, a beam splitter 25, an image forming lens system 33, etc. Then the images of an index mark on the plate 34 and the wafer mark 32X are relayed to an image pickup element 39X. The wavelength band of the irradiating light is set through the filter plate 22 so as to avoid the absorption band of a photoresist on a wafer W.</p> |
