Position detecting method and projection exposure apparatus usin

Details Position detecting method and projection exposure apparatus usin Position detecting method and projection exposure apparatus usin

1993-06-04

1997-01-14

Fahmy, Wael

Optics: measuring and testing

By alignment in lateral direction

With registration indicia

250548, G01N 2186, H01L 21027

Patent

active

055945490

ABSTRACT:
A position detecting method includes illuminating a grating mark of an object with monochromatic light; forming an interference image on an image pickup device by using .+-. n-th order light (n=1, 2, 3 . . . ) among reflective diffraction light from the grating mark; integrating an image signal produced by the image pickup device within a two-dimensional window of a predetermined size set with respect to the image signal and along one direction in two-dimensional coordinates, whereby a one-dimensional projection integration signal is produced; transforming, through rectangular transformation, the one-dimensional projection integration signal into a spatial frequency region; selecting, on the spatial frequency region and from the one-dimensional projection integration signal, a spatial frequency component which appears in the interference image due to the periodicity of the grating mark; and detecting the position of the grating mark on the basis of the selection.

REFERENCES:
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patent: 4886975 (1989-12-01), Murakami et al.
patent: 5017798 (1991-05-01), Murakami et al.
patent: 5120974 (1992-05-01), Muraki
Patent Abstracts of Japan, Kokai No. 61-065251, vol. 10, No. 232, Aug. 1986.
Patent Abstracts of Japan, Kokai No. 03-282715, vol. 16, No. 109, Mar. 1992 .

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