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:
Apr. 23, 2002
Filed:
Aug. 04, 1997
Michael R. Sogard, Menlo Park, CA (US);
John H. McCoy, San Carlos, CA (US);
Nikon Corporation, , JP;
Abstract
A projection exposure apparatus for exposing a semiconductor wafer to a pattern, formed on a reticle, using a projection lens system. An alignment optical system is disposed at a backside of the wafer which is remote from the projection lens system. The alignment optical system detects an alignment mark provided on the frontside of the wafer from the backside of the wafer. Thus the wafer alignment mark is detected without being adversely affected by integrated circuit layers, e.g. photoresist, metallization, etc. applied to the principal surface (frontside) of the wafer, and the reticle and wafer can be aligned accurately. Any tilting or wedging of the wafer, i.e. non-normality to the incident light beam, is detected and corrected for.