| 摘要 |
PURPOSE: To equalize positioning accuracy required in pre-alignment to that at a time when target phase difference between two beat signals takes zero even when the target phase difference takes any value when a reticle and a wafer are aligned by using a heterodyne interference system alignment system. CONSTITUTION: Pre-alignment (105) is conducted on the basis of the quantity of positional displacementΔx (102) between the alignment mark of a reticle and a reference mark and phase differenceΔϕT (104) computed from the phase differenceΔϕ0 of a beat signal corresponding to a reticle mark and a reference diffraction grating mark. Corrected phase differenceΔϕA is obtained so that the difference section of the phase differenceΔϕ1 of a beat signal corresponding to the reticle mark and a wafer mark and the phase differenceΔϕT is kept within a range of±180 deg., and alignment (109) is performed by using the corrected phase differenceΔϕA.
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