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. 30, 1989
Filed:
Jul. 02, 1987
Canon Kabushiki Kaisha, Tokyo, JP;
Abstract
A projection exposure apparatus for projecting a pattern, formed on a reticle, upon a wafer by way of a projection lens system is disclosed. The apparatus includes an alignment system wherein light is projected upon an alignment mark of the wafer by use of the projection lens system, and the light diffracted by an edge of the wafer alignment mark is guidingly directed from between the projection lens system and the wafer to a photoelectric detector without intervention of the projection lens system. From the photodetector, an alignment signal corresponding to the position of the wafer alignment mark is obtained and, on the basis of the alignment mark signal, the wafer and the reticle are brought into a predetermined positional relation. With the disclosed alignment system, the wafer alignment mark can be detected without being affected by a photoresist layer applied to the wafer surface, with the result that the reticle and the wafer can be aligned more accurately.