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:
Dec. 07, 1993
Filed:
Apr. 04, 1991
Tetsuya Mori, Yokohama, JP;
Akiyoshi Suzuki, Tokyo, JP;
Canon Kabushiki Kaisha, Tokyo, JP;
Abstract
A method of positioning a surface of a wafer with respect to a focal plane of an optical system is disclosed. The method includes: forming an image of a pattern in a first region of a wafer through the optical system; projecting through the optical system a radiation beam to the first region of the wafer and projecting through the optical system a reflection beam from the first region of the wafer onto a predetermined plane; evaluating the formed image to determine the focal plane of the optical system and determining, as a reference position, a position of incidence on the predetermined plane of the reflection beam from the first region of the wafer at a level corresponding to the determined focal plane; projecting a radiation beam to a second region of the wafer and projecting through the optical system a reflection beam from the second region of the wafer onto the predetermined plane; and positioning the second region of the wafer on the determined focal plane of the optical system on the basis of a position of incidence of the reflection beam from the second region of the wafer with respect to the determined reference position.