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:
May. 17, 1988
Filed:
Jul. 16, 1986
Applicant:
Inventors:
Assignee:
Hitachi, Ltd., Tokyo, JP;
Attorney:
Primary Examiner:
Assistant Examiner:
Int. Cl.
CPC ...
G01B / ;
U.S. Cl.
CPC ...
356401 ;
Abstract
In an alignment detection optical system designed to observe an alignment pattern of a mask and an image of an alignment pattern of a wafer formed on the alignment pattern of the mask by a projection lens in a projection type aligner, there is provided a spatial filter designed to select only the reflected light having a desired reflection angle from the light reflected by the alignment pattern composed of steps formed on a surface of the wafer.