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:
Mar. 28, 1989
Filed:
Jan. 19, 1988
NEC Corporation, Tokyo, JP;
Abstract
A method of alignment between a mask and a semiconductor wafer is disclosed. At least one linear Fresnel zone plate lens is provided on the mask, and first and second reflecting gratings are provided one the semiconductor wafer. The first reflecting grating includes a plurality of concaves or convexs arranged with a constant pitch P.sub.1, and the second reflecting grating includes a plurality of concaves of convexs arranged with a constant pitch P.sub.2 different from the pitch P.sub.1 in the first reflecting grating. A monochromatic radiation is irradiated on the mask and first and second reflected radiations from the first and second reflecting gratings are detected by first and second detectors, respectively. A difference value between the outputs of the first and second detectors is obtained, and the relative position between the mask and the semiconductor wafer is displaced in accordance with the difference value.