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. 21, 2001
Filed:
Oct. 13, 1999
Kenji Morita, Kawagoe, JP;
Nikon Corporation, Tokyo, JP;
Abstract
Apparatus and methods are disclosed for performing microlithography of a pattern defined by a reticle that is divided (segmented) into multiple exposure units. During exposure of each exposure unit, appropriate focal-point corrections are made according to variations in feature density and feature distribution within individual exposure units. Each exposure unit is divided into multiple subregions. The proportion of the area of each subregion occupied by actual pattern features is determined. A mean (average) feature density in the exposure unit is calculated based on the minimum (not zero) surface area of features and the maximum surface area of features. Based on the result of such a calculation, the focal point for the exposure unit is adjusted as required using a focal-point correction lens.
Data source: USPTO (United States Patent and Trademark Office) public patent records. Weekly synchronization. How IDiyas builds this profile