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:
Nov. 23, 1999
Filed:
Nov. 05, 1997
Koichiro Narimatsu, Tokyo, JP;
Mitsubishi Denki Kabushiki Kaisha, Tokyo, JP;
Abstract
A step and scan exposure system projects a reticle image onto a semiconductor wafer mounted on a semiconductor wafer stage by a projection optical system in a slit scan scheme, focusing illumination light on the semiconductor wafer to form a plurality of focus sense areas arranged in a direction perpendicular to a scanning direction, receiving reflected illumination light by a plurality of photodetectors, and controlling the wafer stage by the signals from the plurality of photodetectors. In one embodiment, the signals from the plurality of photodetectors are selected, for controlling the wafer stage, corresponding to designated regions for focusing on the semiconductor wafer.