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:
Oct. 17, 2006
Filed:
Jul. 23, 2004
Shinji Sugihara, Tokyo, JP;
Riki Ogawa, Kawasaki, JP;
Toru Tojo, Naka-gun, JP;
Kabushiki Kaisha Toshiba, Tokyo, JP;
Abstract
An automatic focusing apparatus comprises a stage holding a substrate, an objective lens disposed facing the substrate surface, an illumination optics illuminating the substrate surface with a spotted light beam from an oblique direction, a photodetector detecting reflected light from the substrate surface, a position detection circuit detecting a vertical position of the substrate surface from an electric signal obtained from the photodetector to output a position signal, a correction circuit monitoring the position signal in real time and subtracting a surplus exceeding a signal change corresponding to a surface shape change of the substrate from the position signal, when a change amount per unit time of the position signal exceeds a predetermined level and outputting a corrected position signal, and a stage control circuit controlling the vertical position of the stage based on the corrected position signal.