Radiant energy – Photocells; circuits and apparatus – With circuit for evaluating a web – strand – strip – or sheet
Patent
1997-09-09
1999-08-24
Le, Que T.
Radiant energy
Photocells; circuits and apparatus
With circuit for evaluating a web, strand, strip, or sheet
2505594, G01N 2186
Patent
active
059427639
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.
REFERENCES:
patent: 5465145 (1995-11-01), Nakashige et al.
Le Que T.
Mitsubishi Denki & Kabushiki Kaisha
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