Devices and methods for reading identification marks on semicond

Details Devices and methods for reading identification marks on semicond Devices and methods for reading identification marks on semicond

1993-11-19

1995-01-31

Couso, Yon J.

Image analysis

Histogram processing

For setting a threshold

382 1, 414417, 414749, 348143, G06K 900, B65G 106

Patent

active

053864816

ABSTRACT:
Methods and apparatus for machine reading of identification marks incised on semiconductor wafers. Preferred apparatus makes it possible to view the mark either as a dark image on a light background (which is in itself novel) or as a light image on a dark background. Using a television camera and an optical character reader, the viewing method can be changed automatically if a preset confidence level is not reached, and provides a signal if neither method (or the combination of the two methods) gives a satisfactory result. The method is particularly useful for successively reading the identification marks on a number of wafers stacked in a cassette. Preferred apparatus for such reading comprises a wafer support which can be pushed upwards from underneath the cassette so that the wafer to be identified rests on one ledge of the support and the adjacent wafer rests on another higher ledge on the support, thus exposing and precisely locating the identification mark on the first wafer.

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Hine Design Proofreader Trade Brochure May 1989.
Search Report EP 91 90 4111, Nov. 19, 1992.

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