To measure and adjust the cross angle and the relative rotary error of two laser beams for alignment accurately and speedily by calculating the position relationship between the two beams for a reference diffraction mark based on light information from a plurality of parts on the reference diffraction mark.
P polarization beams LB1P and LB2P that has passed through a polarization beam splitter(PBS) 19 become parallel luminous flux inclined by a specific angle by a lens 24, and enter an objective lens 29 via a lens 26. The beams LB1P and LB2P emitted from the objective lens 29 become parallel luminous flux that are inclined at angles symmetrical with a light axis AX relative to the grating arrangement direction of a wafer mark and enter at a specific cross angle from two directions and form an image. A phase detection system 32 input light beat signals SD and SR from photo detectors 31 and 23 to obtain a phase difference. A main control device MCS position a wafer W at a specific position based on the phase difference information from the phase detection system 32 and the position information from a laser interferometer 35.
UMAGOME NOBUTAKA
MIZUTANI HIDEO
KOMATSU KOICHIRO
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