Alignment apparatus utilizing a plurality of wavelengths

Details Alignment apparatus utilizing a plurality of wavelengths Alignment apparatus utilizing a plurality of wavelengths

1995-10-26

1997-02-11

Gonzalez, Frank

Optics: measuring and testing

By polarized light examination

With birefringent element

356349, 250548, G01B 902

Patent

active

056026447

ABSTRACT:
Two-colored illumination light emitted from first and second laser beam sources illuminates a reticle mark and a wafer mark. Diffraction light from the reticle mark and the wafer mark is received by two photoelectric detection elements, respectively. The one photoelectric element receives single-colored diffraction light from light of the first light source through a color filter to generate a reticle beat signal. The other photoelectric element receives two-colored light to generate a wafer beat signal. A phase difference between the reticle beat signal and the wafer beat signal when shutting off the second laser beam source is aligned with a phase difference between the two signals produced when turning on the second laser beam source and decreasing the power of the first laser light source.

REFERENCES:
patent: 5171999 (1992-12-01), Komatsu et al.
patent: 5347356 (1994-09-01), Ota et al.
patent: 5530256 (1996-06-01), Mizutani et al.
patent: 5530257 (1996-06-01), Mizutani et al.

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