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:
Jan. 20, 1998
Filed:
Nov. 29, 1995
Shinji Utamura, Utsunomiya, JP;
Canon Kabushiki Kaisha, Tokyo, JP;
Abstract
An aligner for exposing a pattern image of an original plate by projecting the image onto an exposure surface of a substrate, which is held on a table, in a focused state through a projection optical system includes a defocusing detection device for detecting a deviation from a focusing position at each of a plurality of points within an exposure region on the surface of the substrate, which is arranged at an exposure position, a device for determining an approximate plane of the exposure surface of the substrate within the exposure region on the basis of deviation detection values detected at the plurality of points by the defocusing detection device and a decision device for determining a deviation of the approximate plane of the exposure surface of the substrate, on the basis of the deviation detection values detected at each of the plurality of points, to decide whether contamination is present between the table and the back side of the substrate. Also disclosed is a contamination detecting method applied to such an aligner.