Radiant energy – Photocells; circuits and apparatus – Optical or pre-photocell system
Patent
1993-08-20
1994-10-11
Nelms, David C.
Radiant energy
Photocells; circuits and apparatus
Optical or pre-photocell system
250223R, 414331, G01N 2186
Patent
active
053549953
ABSTRACT:
A device for detecting a semiconductor wafer in a non-contact manner irrespective of transparency or opacity thereof. At positions corresponding to a plurality of wafers loaded on a carrier, a plurality of light emitting/receiving sensors and a plurality of light receiving sensors are correspondingly provided in pairs in such a manner that their respective light emitting/receiving surfaces and their respective light receiving surface in pairs confront each other. The light emitting/receiving sensors and light receiving sensors are alternately arranged in two rows lengthwise on a sensor support board. In the case of a transparent wafer, a light sent out from a light emitting section of the light emitting/receiving sensor strikes on and is reflected by the surface of the wafer. The thus reflected light is then detected by a light receiving section of the same light emitting/receiving sensor. In the presence of an opaque wafer, a light sent out from the light emitting/receiving sensor is not permitted to reach the confronting light receiving sensor. Conversely, in the absence of the opaque wafer, the light reaches the light receiving sensor for detection. On the other hand, there is provided a judgment section switchably inputting one of a light reception signal generated at the light receiving section of the light emitting/receiving sensor and a light reception signal generated at the light receiving section of the light receiving sensor.
REFERENCES:
patent: 4540887 (1985-09-01), Minerd et al.
patent: 5194743 (1993-03-01), Aoyama et al.
patent: 5225691 (1993-07-01), Power et al.
patent: 5239182 (1993-08-01), Tateyama et al.
Asakawa Masato
Endo Shunetsu
Kato Mitsuo
Allen Stephone B.
Nelms David C.
Tokyo Electron Kabushiki Kaisha
Tokyo Electron Tohoku Kabushiki Kaisha
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