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:
Oct. 31, 1995
Filed:
Apr. 16, 1993
Hiroshi Morioka, Ebina, JP;
Minori Noguchi, Yokohama, JP;
Yoshimasa Ohshima, Yokohama, JP;
Yukio Kembo, Yokohama, JP;
Hidetoshi Nishiyama, Fujisawa, JP;
Kazuhiko Matsuoka, Gunma, JP;
Yoshiharu Shigyo, Takasaki, JP;
Hitachi, Ltd., Tokyo, JP;
Abstract
A defect detecting apparatus including an illumination system for radiating a light of a plane wave linearly to a substrate having repetitive patterns of different pitches; a focusing optical system for focusing a light image reflected from the substrate thus illuminated by the illumination system; a spatial filter disposed intermediate the focusing optical system so as to shield a diffraction light from repetitive patterns of a small pitch on the substrate; a detector for detecting the light image formed by the focusing optical system; an erasing means for comparing and erasing signals which are generated on the basis of repetitive patterns of a large pitch and obtained through the spatial filter, out of signals detected by the detector; and a defect detecting means for detecting defects on the substrate in accordance with a signal detected by the detector, as well as a method applied to the said apparatus.