Visual defect inspection of masks

Details Visual defect inspection of masks Visual defect inspection of masks

1981-10-16

1984-02-21

McGraw, Vincent P.

Optics: measuring and testing

Inspection of flaws or impurities

Having predetermined light transmission regions

350523, G01N 2188, G02B 2108

Patent

active

044326416

ABSTRACT:
An optical system and method for direct human eye visual inspection of specimens of photoresist coated masks for defects as small as 2 .mu.m. The specimens are uniformly illuminated with a partially coherent sodium light that has very high illuminance and constrast levels. The system consists of a high pressure (1-1.5 atmosphere) sodium lamp source projected onto the specimen by a Kohler-type illumination system.

REFERENCES:
patent: 3318184 (1967-05-01), Jackson
patent: 3860335 (1978-01-01), Caprari
R. Kingslake, Applied Optics and Optical Engineering, vol. 1, pp. 10-16, 1965, New York and London.
L. C. Martin, An Introduction to Applied Optics, vol. II, pp. 218-222, 1932, London.
Hardy and Perrin, The Principles of Optics, pp. 536-537, 1932, published by McGraw Hill.

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