Apparatus for inspecting defects and foreign substances having a

Details Apparatus for inspecting defects and foreign substances having a Apparatus for inspecting defects and foreign substances having a

1993-09-22

1995-08-15

Nelms, David C.

Radiant energy

Photocells; circuits and apparatus

With circuit for evaluating a web, strand, strip, or sheet

356237, G01N 2188

Patent

active

054421896

ABSTRACT:
An apparatus for inspecting defects and foreign substances on an object to be inspected comprises: an illumination optical system for illuminating a spot of illuminated area on a semiconductor wafer; a lens for executing Fourier transform of the patterns of said illuminated area; a spatial filter for blocking the components of the resultant Fourier transform images corresponding to the patterns having no defects; a lens for executing inverse Fourier transform of the light which is transmitted through the spatial filter to form images of the defect(s); and a photo detector array for receiving the images of the defect(s).

REFERENCES:
patent: Re33956 (1992-06-01), Lin et al.
patent: 3614232 (1971-10-01), Mathiseu
patent: 4806774 (1989-02-01), Lin et al.
patent: 4845356 (1989-07-01), Baker

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