Received 18 December 2020; revised 19 May 2021; accepted 21 May
2021
A new series of experiments was conducted
to determine the source of impurities in the process of
silicon crystal growth with electron beam heating. A
gas-dynamic window was placed between the electron gun and
growth chamber. Also positively-charged traps were placed
along the crucible to reduce the number of electrons hitting
the chamber and the crucible. Five experiments were conducted:
two with the window, two with charge traps, and one with both
the window and charge traps.
The analysis of obtained samples showed that the gas-dynamic
window decreases the content of Al, Cu, Fe, Cr and O2,
and the trap, used in the experiments, decreases the content
of Fe, Cr and Cu in residues of the melt. The content of all
impurities, except Al, is close to the goal level.
Al impurities come only from the gun, but the gas-dynamic
window cannot eliminate them completely. It seems that Al
impurities come either as neutral atoms carried by the gas or
as positively charged ions. To reduce these impurities, a
separation of the Al flow from the beam by the magnetic field
is proposed.
Keywords: electron
optics, materials testing and analysis, silicon, doping and ion
implantation
PACS: 41.85.-p, 81.70.-q, 61.72.uf
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