Radiant energy – Photocells; circuits and apparatus – Optical or pre-photocell system
Patent
1992-02-10
1993-08-03
Nelms, David C.
Radiant energy
Photocells; circuits and apparatus
Optical or pre-photocell system
356237, G01N 2188
Patent
active
052332039
ABSTRACT:
An apparatus for detecting surface defects of a wafer includes a rotary unit rotatably attached to a vertical surface of a Z-X unit provided on a vertical surface of an L-shaped base and rotated with a vertically oriented semiconductor wafer held thereon by an attractive force of negative pressure created inside the rotary unit by evacuation of the air therein. An optical microscope is provided, which has its optical axis normal to the vertical surface of the wafer. The field of the microscope is moved smoothly along a radius direction of the wafer including the edge and the center of the wafer by the Z-X unit. At the same time, the wafer surface is illuminated by a spot laser beam, and blown by clean air ejected from a nozzle. The entire wafer surface is optically inspected by the optical microscope to receive reflected light which is detected by a photomultiplier for detecting deflects, such as particles, on the wafer surface.
REFERENCES:
patent: 4740708 (1988-04-01), Batchelder
patent: 4943732 (1990-07-01), Economou
patent: 5127726 (1992-07-01), Moran
Lee John R.
NEC Corporation
Nelms David C.
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