Optics: measuring and testing – By dispersed light spectroscopy – Utilizing a spectrometer
Patent
1990-10-09
1992-05-19
Turner, Samuel A.
Optics: measuring and testing
By dispersed light spectroscopy
Utilizing a spectrometer
356355, 356384, G01B 902
Patent
active
051142333
ABSTRACT:
The present invention is predicted upon the discovery by applicants that is scattered light from an etched workpiece is measured over many orders of diffraction, important characteristics of the etched workpiece can be correlated with the principal component content of the intensity characteristic. In accordance with the present invention, an etched workpiece is inspected by 1) exposing the workpiece to a beam of coherent light, 2) measuring the intensity of the light scattered from the workpiece over a range of spatial frequencies corresponding to a plurality of diffraction orders, 3) determining the principal component content of the tested workpiece intensity envelope, and 4) accepting or rejecting the workpiece in accordance with whether or not the principal component content satisfies predetermined criteria. In preferred embodiments the principal components are determined in relation to a plurality of reference measurements by singular value decomposition.
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Clark Linda A.
Gottscho Richard A.
Kruskal Joseph B.
Lambert Diane
AT&T Bell Laboratories
Books Glen E.
Turner Samuel A.
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