Image analysis – Histogram processing – For setting a threshold
Patent
1990-02-01
1991-09-03
Moore, David K.
Image analysis
Histogram processing
For setting a threshold
382 30, 382 41, G06K 900
Patent
active
050461095
ABSTRACT:
An apparatus for inspecting a pattern formed on an object such as a mask or a reticle in accordance with design data includes a character extraction circuit that employs a multiplicity of templates for detecting any of a plurality of different types of bends of an edge of the pattern with respect to a reference edge, for any of a plurality of rotation angles of the reference edge. Although a large number of templates is employed, template outputs are sorted into a small number of groups, and a comparison is made between synthesized template outputs for data representing an image of a pattern region on the object and for corresponding reference data. The apparatus also includes a direct comparison circuit for comparing image data and reference data to detect defects in the pattern and to determine the size of any defect along different directions (ignoring size along an edge of the pattern). The direct comparison circuit also determines the maximum size of the defect along the different directions. A dead band is provided about the edge of the pattern to reduce the detection of a false defect by the direct comparison circuit. However, the character extraction circuit is capable of detecting any defect throughout the pattern.
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Fujimori Yoshihiko
Hirose Keiichi
Couso Jose L.
Moore David K.
Nikon Corporation
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