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Proceedings Paper

Morphology of silicon wafer surfaces: a comparative study with atomic force microscopy and other techniques
Author(s): Peter Wagner; H. A. Gerber; D. Graef; R. Schmolke; M. Suhren
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Paper Abstract

Morphology and topography of mirror polished silicon wafer surfaces were investigated with profiling and light scattering techniques, including in particular Atomic Force Microscope. Roughness <EQ 0.1 nm rms is observed on a lateral scale ranging from about 20 nm up to 10 micrometers in close agreement with values expected from surface topography models composed of atomic steps. Defects consisting of tiny etch pits occur with a low density. These pits are crystal defects delineated by treatment of the silicon wafers with SC1-solution or by polishing. Occurrence of pits in pairs is common but single pits are also observed. The shape of the pits resembles an inverted pyramid with a square or rectangular base. Details of the pits' shape are influenced by the delineation process selected. Pits observed after polishing display a smoother transition region between the very pit itself and the surrounding surface as compared to pits delineated by SC1-treatment. Smoother pits have a smaller effective cross section for light scattering with respect to specific types of surface inspection instruments. This results in significant differences in counts of light scattering defects when surface inspection tools of various suppliers are used. The effect can be explained by considering the spatial frequency bandwidth of the various surface inspection instruments used. Bandwidth differences are also responsible for differences in rms roughness values as reported by profiling instruments.

Paper Details

Date Published: 4 November 1996
PDF: 10 pages
Proc. SPIE 2862, Flatness, Roughness, and Discrete Defect Characterization for Computer Disks, Wafers, and Flat Panel Displays, (4 November 1996); doi: 10.1117/12.256205
Show Author Affiliations
Peter Wagner, Wacker Siltronic GmbH (Germany)
H. A. Gerber, Wacker Siltronic GmbH (Germany)
D. Graef, Wacker Siltronic GmbH (Germany)
R. Schmolke, Wacker Siltronic GmbH (Germany)
M. Suhren, Wacker Siltronic GmbH (Germany)

Published in SPIE Proceedings Vol. 2862:
Flatness, Roughness, and Discrete Defect Characterization for Computer Disks, Wafers, and Flat Panel Displays
John C. Stover, Editor(s)

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