SYMPOSIA PAPER Published: 01 January 1963

Infrared-Tested Surface Properties of Semiconductor Wafers


The infrared (IR) transmission of semiconductor materials is known to be sensitive to the thickness of the specimen, its conductivity, and its surface properties. In this paper special attention has been paid to surface reflection phenomena and their influence on IR transmission. When those measurements are performed at a proper wavelength, for instance, at 2500 mμ, no decrease of IR transmission has been observed up to a wafer thickness of 1 mm in a conductivity range from intrinsic to 0.1 ohm-cm for n-doped germanium and from intrinsic to 1 ohm-cm for p-doped germanium and silicon. In this range of measurements, therefore, the IR transmission is affected only by surface reflection. Since the average diameter of surface defects in practice is just on the order of the wavelength, IR transmission is heavily influenced by surface irregularities. Furthermore surface films 0.02 μ thick and over have shown remarkable influence on IR transmission. The method has been applied to the investigation of several processes such as lapping, etching, and cleaning of germanium and silicon wafers. Under certain circumstances storage of wafers has an influence on surface properties. Studies also have been performed on the etching mechanism of different etching solutions by plotting IR transmission versus removed thickness of material.

Author Information

Bogenschuetz, A.
Research Laboratory, Ulm-Donau, Germany
Schuetze, H.
Research Laboratory, Ulm-Donau, Germany
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Developed by Committee: F01
Pages: 222–232
DOI: 10.1520/STP44496S
ISBN-EB: 978-0-8031-6211-2
ISBN-13: 978-0-8031-6139-9