| 摘要 |
PURPOSE:To enable various kinds of wafers to be coped with by changing over the foreign matter detecting processes by a method wherein a wavelength separating mirror or a polarized beam splitter is selectively inserted into the optical path of reflected light of wafers. CONSTITUTION:When the foreign matter of a wafer in larger grain size on the surface of a pattern is detected, a wavelength separating dichroic mirror 10 is inserted into an optical path and then S polarization laser oscillators 11, 12 and laser oscillators 13, 14 are simultaneously operated. On the other hand, when the foreign matter of a wafer in small step of pattern is etched, a polarized beam splitter 18 is inserted into the optical path and the S polarization laser oscillators 11, 12 only are operated. Through these procedures, the foreign matter detecting processes can be changed over conforming to the kinds of wafers to be detected enabling various kinds of wafers to be coped with.
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