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:
Aug. 28, 1990
Filed:
Jan. 10, 1990
Canon Kabushiki Kaisha, Tokyo, JP;
Abstract
A projection exposure apparatus is disclosed for exposing a semiconductor wafer to a pattern, formed on a reticle, by projection using a projection lens system. The apparatus includes an alignment optical system disposed at a side of the wafer remote from the projection lens system. The alignment optical system is used to detect an alignment mark provided on the wafer, from the back of the wafer. In accordance with the detection, the wafer is moved so that its alignment mark is brought into a predetermined positional relation with the alignment optical system, whereby the reticle and the wafer are relatively aligned. With this arrangement, the wafer alignment mark can be detected without being adversely affected by a resist layer applied to the wafer surface. Thus, the reticle and the wafer can be aligned very accurately.