Optics: measuring and testing – By alignment in lateral direction – With registration indicia
Patent
1997-01-21
1999-11-30
Hantis, K. P.
Optics: measuring and testing
By alignment in lateral direction
With registration indicia
G01B 1100
Patent
active
059952342
ABSTRACT:
Method comprises a process for obtaining a photoelectric signal with a waveform having a pair of extremal values at respective positions corresponding to a pair of edge portions of an alignment mark by photoelectrically detecting the reflected light from the alignment mark on a substrate; a first determination process for determining the position of the alignment mark on the basis of a pair of slope portions existing inside the pair of extremal values of the photoelectric signal waveform; a second determination process for determining the position of the alignment mark on the basis of a pair of slope portions existing outside the pair of extremal values of the photoelectric signal waveform; a third determination process for determining the position of the alignment mark on the basis of both a pair of slope portions existing inside said pair of extremal values of the photoelectric signal waveform and a pair of slope portions existing outside; and a process for selecting any one of the first determination process, second determination process, or third determination process in accordance with the objective alignment accuracy of the substrate.
REFERENCES:
patent: 4860374 (1989-08-01), Murakami et al.
patent: 4962318 (1990-10-01), Nishi
patent: 5153678 (1992-10-01), Ota
Hantis K. P.
Nikon Corporation
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