| 摘要 |
PURPOSE:To reduce a detection error caused by the interference of detecting beams, and to enable detection with excellent reproducibility by separately detecting electric signals at every wavelength and detecting the quantity of displacement from a reference surface on the basis of a plurality of detecting signals. CONSTITUTION:A plurality of light sources having different wavelengths are used while an angle theta formed by a wafer and incident beams to the wafer is brought to 10 deg. or less, and S polarized light to the wafer is employed as detecting beams. The interference action of detecting beams reflected by a surface to be detected and a section in the vicinity of the surface to be detected is levelled, and a detection error due to the interference action of detecting beams is reduced. Consequently, a plurality of beam having different wavelengths are used, surface-position detecting signals by these beams are detected separately at every wavelength, and the position of the surface is obtained on the basis of these signals. Accordingly, the detection error caused by the interference of detecting beam when there are plurality of refelecting surfaces to detection luminous flux as with the surface of the wafer 2 on which a resist 14 is applied is reduced, thus accurately detecting the position of the surface of the wafer 2 with excellent reproducibility. |
