The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Sep. 03, 1991
Filed:
Feb. 01, 1990
Yoshihiko Fujimori, Tokyo, JP;
Keiichi Hirose, Tokyo, JP;
Nikon Corporation, Tokyo, JP;
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.