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Proceedings Paper

Investigations of smooth surfaces by measuring the BRDF with a stray light sensor in comparison with PSD curves evaluated from topography of large AFM scans
Author(s): Hendrik Rothe; Dorothee Hueser; Andre Kasper; Thomas Rinder
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Paper Abstract

For quality inspection of polished surfaces as applied in semiconductor and optical industry, various methods are used for a fast detection of microroughness, defects, and contaminations. With the aid of stray light sensors the intensity distribution of the reflected and scattered light, i.e. the BRDF, is measured. The probability distribution of values of a BRDF is parametrized to obtain a measure for roughness and for classes of defects. There is still need for justifying the choice of statistical moments to characterize and finally to classify different surfaces. Of course, a basic quantitative, i.e. metrological understanding of stray light sensors is necessary. The power spectrum of surface topographies sufficiently smooth to obey Rayleigh-Rice approximation is proportional to the BRDF. Therefore a comparison was only carried out with sample surfaces obeying this approximation. Defects and contaminations with lateral sizes smaller than the wavelength of the illuminating light employed in the stray light sensor, however, could not be analyzed within this investigation. We have measured the topography of large areas up to 600 micrometer X 100 micrometer with an AFM by patching several scans (up to 8) with overlap. BRDFs evaluated from AFM measurements agree well with BRDFs measured with a stray light sensor.

Paper Details

Date Published: 29 March 1999
PDF: 9 pages
Proc. SPIE 3619, Surface Characterization for Computer Disks, Wafers, and Flat Panel Displays, (29 March 1999); doi: 10.1117/12.343705
Show Author Affiliations
Hendrik Rothe, Univ. of the Federal Armed Forces (Germany)
Dorothee Hueser, Univ. of the Federal Armed Forces (Germany)
Andre Kasper, Univ. of the Federal Armed Forces (Germany)
Thomas Rinder, Univ. of the Federal Armed Forces (Germany)

Published in SPIE Proceedings Vol. 3619:
Surface Characterization for Computer Disks, Wafers, and Flat Panel Displays
John C. Stover, Editor(s)

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