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. 25, 2001
Filed:
Nov. 03, 1998
Tetsuo Taniguchi, Ageo, JP;
Nikon Corporation, Tokyo, JP;
Abstract
A transparent correcting plate is disposed between a reticle and a projection optical system. The correcting plate can be selectively inserted and withdrawn by a changing device. The correcting plate can be changed for another correcting plate stored in a storage unit according to need. The correcting plate has been polished so as to be capable of correcting random distortion, and thus it corrects random distortion produced by a projection exposure apparatus in which it is used. Further, a correcting plate is selected according to image distortion characteristics of a projection exposure apparatus used in the preceding exposure process or a projection exposure apparatus to be used in the subsequent process, thereby correcting the distortion of a projected image, and thus improving the overlay accuracy between two layers.