Method and device for detecting the center of a wafer

Details Method and device for detecting the center of a wafer Method and device for detecting the center of a wafer

1992-03-13

1993-11-23

Rosenberger, Richard A.

Optics: measuring and testing

By alignment in lateral direction

With light detector

356150, H01L 2168

Patent

active

052649180

ABSTRACT:
A wafer center detecting method comprises steps of giving turn to a wafer held by a holder, optically detecting two points at which the true rim line of the wafer crosses the fictitious rim line thereof obtained when the center of the wafer is in accord with the rotation center of the holder, and measuring an angle formed by these two intersecting points relative to a reference point, obtaining from the angle formed by the two intersecting points a direction in which the center of the wafer is shifted from the rotation center of the holder, obtaining a central angle formed by the two intersecting points relative to the rotation center of the holder, and obtaining, on the basis of the central angle and a previously-measured wafer radius, the extent to which the center of the wafer is shifted from the rotation center of the holder.

REFERENCES:
patent: 3604940 (1971-09-01), Matthews
patent: 4607035 (1990-03-01), Galburt et al.
patent: 5125791 (1992-06-01), Volovich

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