Application of magnetic fields in industrial growth of silicon single crystals

W. von Ammon¹ - Yu. Gelfgat² - L. Gorbunov² - A. Mülbauer³ - A. Muiżnieks^3,4 - Y. Makarov⁵ - J. Virbulis⁶ - G. Müller⁷

¹ Siltronic AG, 24 Johannes Hess Str., 84489 Burghausen, Germany
² Institute of Physics, University of Latvia, 32 Miera Str., Salaspils--1, LV-2169, Latvia
³ Institute for Electroheat, University of Hanover, 4 Wilhlem-Busch-Str., D-30167 Hanover, Germany
⁴ Faculty of Physics and Mathematics, University of Latvia, 8 Zellu Str., LV-1002 Riga, Latvia
⁵ Semiconductor Technology Research, Inc., P.O.Box70604, Richmond, VA 23255-0604, USA
⁶ PAIC, Riga, LV-1002, 8 Zellu Str., Latvia
⁷ Crystal Growth Laboratory, Fraunhofer IISB, Schottkystrasse 10, D-91058 Erlangen, Germany

Abstract
The use of magnetic fields for the growth of semiconductor crystals has already been considered many decades ago. As early as in 1966, Chedzey \etal \cite{1} and Utech \etal \cite{2} reported about InSb crystals grown in a horizontal boat under the influence of a magnetic field. They found a suppression of temperature fluctuations in the InSb melt and a decrease of growth variations (striations) in the crystal. In 1970, Witt \etal \cite{3} applied a static transverse (horizontal) magnetic field to the Czochralski (CZ) growth of InSb crystals. 10 years later, in 1980, the transverse field was also used for the CZ growth of silicon single crystals \cite{4,5}. Since then, the method has received considerable attention over the years. One of the major driving forces for introducing magnetic fields in the industrial CZ growth of silicon crystals was the request by the semiconductor industry to replace floating zone (FZ) grown crystals, which had been the preferred substrate material for the manufacturing of high power devices, by low oxygen CZ crystals \cite{6}. The reason for this changeover was the fact that the FZ method in the early 80's could not follow the rapid crystal diameter increase as required by the industry, namely, the switch from 4" to 5" diameter in the early 80's. The application of magnetic fields to the CZ technique (MCZ) allowed the growth of low oxygen crystals with the required diameter and having similar properties as the FZ grown crystals. Figs 12, Refs 59.