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The Etch Rate Variations of p+ Silicon Wafers in Aqueous KOH Solutions as a Function of Processing Conditions

Published online by Cambridge University Press:  10 February 2011

P. Kilpinen ,
E. Haimi  and
V.K. Lindroos
P. Kilpinen
Affiliation:
E-mail: Petteri.Kilpinen@hut.fi
E. Haimi
Affiliation:
Laboratory of Physical Metallurgy and Materials Science, Helsinki University of Technology, P.O.Box 6200, FIN-02015 HUT, FINLAND
V.K. Lindroos
Affiliation:
Laboratory of Physical Metallurgy and Materials Science, Helsinki University of Technology, P.O.Box 6200, FIN-02015 HUT, FINLAND
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Abstract

The etching behaviour of highly boron doped (20 - 25 mω-cm) silicon wafers in aqueous KOH solutions were investigated in the present study. The etch rate of (100) crystal plane and the fastest etch plane projections (31X) and (41X), where X can be 0,1,2…, were measured as a function of processing conditions. The experimental temperatures of solutions were 65 - 75°C and the concentrations 5 - 40 wt-% KOH. The maximum etch rate of (100) crystal plane was measured to locate between 10 - 15 wt-% KOH and the maximum etch rates of fastest etch plane projections were measured to locate between 0 - 10 wt-% KOH in the whole temperature range. In lower concentrations (5 - 20 wt-% KOH) the fastest etch plane projection was determined to be (31X) crystal plane projection. In higher concentrations (25 - 40 wt-% KOH) it was determined to be (41X) crystal plane projection. The results of the present study indicate that there are differences between etch reactions of different etch planes. The difference may be connected to transferring electrons. This could explain why the different etch planes have the position of etch rate maximums as a function of KOH concentration in different places. Furthermore, this could also explain why fastest etch planes are sensitive to experimental conditions.

Keywords

KOHSiliconAnisotropic etching
Type
Research Article
Information
MRS Online Proceedings Library (OPL) , Volume 605: Symposium MM – Materials Science of Microelectromechanical Systems Devices II , 1999 , 293
Copyright
Copyright © Materials Research Society 2000

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