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Proceedings Paper

Applications Of A Two-Wavelength Laser Scanner For Material/Device Characterization
Author(s): B. L. Sopori
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Paper Abstract

Applications of a two-wavelength laser scanner for evaluating spatial variations in several material/device parameters WI semiconductors are described. Use of two-wavelength scanning (λ = 1.15 pm and λ = 6328 A) permits excitation and collection of carriers from different depths below the surface of a semiconductor, thereby allowing separation of bulk and near surface (such as a surface junction) characteristics. These characteristics include minority carrier diffusion length, junction recombination, and local variations in photovoltaic effects caused by localized defects, twins and grain boundaries. Laser scanning may be done in two different modes. 1. Carrier generation and collection along the same direction -- in this mode the signal is related to carrier recombination effects. It is shown that the signal due to long wavelength excitation is proportional to the bulk diffusion length. Measurements may be done either on unprocessed substrates using a transparent electrode and capacitive coupling, or following P-N junction formation at the surface. 2. Carrier excitation and collection normal to each other -- this mode is used in unprocessed substrates (single or polycrystalline) to determine lateral variations in the internal fields arising from such effects as impurity inhomogeneities and grain boundaries.

Paper Details

Date Published: 30 April 1981
PDF: 11 pages
Proc. SPIE 0276, Optical Characterization Techniques for Semiconductor Technology, (30 April 1981);
Show Author Affiliations
B. L. Sopori, Motorola Inc. (United States)

Published in SPIE Proceedings Vol. 0276:
Optical Characterization Techniques for Semiconductor Technology
David E. Aspnes; Roy F. Potter; Samuel S. So, Editor(s)

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