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. 24, 1999
Filed:
Sep. 09, 1997
Yasukazu Mukogawa, Tokyo, JP;
Mitsubishi Denki Kabushiki Kaisha, Tokyo, JP;
Abstract
A wafer (1) on which an oxide film (3) is formed is disposed on a wafer stage (2), and the surface of the oxide film (3) is irradiated with a laser beam by a laser-beam irradiation unit (4). Then, the laser beam applied to a region having a concave portion (13) is scattered in the surface of the oxide film (3) due to the level difference of the concave portion (13). Accordingly, through a scanning with the laser beam, the scattered light due to the concave portion (13) is received by a scattered-light receptor (5). Subsequently, information on distribution of the scattered light received by the scattered-light receptor (5) is converted into a potential and an OCR process is performed on the potential distribution by an OCR process unit (6), to read the configuration of the concave portion (13) formed in the surface of the oxide film (3) as character information. With this structure, provided is a wafer identification apparatus which is capable of reading an engraved mark on the surface of the wafer with reliability, even if the oxide film and the like is formed on the wafer.