ISSN 10637397, Russian Microelectronics, 2011, Vol. 40, No. 8, pp. 559–561. © Pleiades Publishing, Ltd., 2011.
Original Russian Text © V.M. Ivanov, Yu.V. Trubitsin, 2010, published in Izvestiya Vysshikh Uchebnykh Zavedenii. Materialy Elektronnoi Tekhniki, 2010, No. 4, pp. 10–13.
The world polysilicon industry is currently in a
complicated situation. The pressing need for alterna
tive energy sources has encouraged demand for solar
energy technologies, which rely heavily on polysili
con, but actual sales of the material have declined as a
result of the recession global recession. Cutting pro
duction costs seems to be crucial for dealing with the
crisis successfully, because it should stimulate the
demand for photovoltaics from businesses and indi
viduals. Above all, this strategy means adopting
resourceefficient technologies, in which byproduct
recycling plays an important part .
This paper is concerned with one such byproduct,
silicon tetrachloride (STC). The importance of the
topic is illustrated by the fact that producing each kilo
gram of polysilicon also yields the following amounts
of STC, depending on process technology:
(1) 2–5 kg with silicon hydrochlorination in mak
(2) 11–14 kg with hydrogen reduction of trichlo
(3) 22–27 kg with trichlorosilane disproportion
ation as part of the silane process technology.
The current practices in STC utilization involve its
hydrogenation to trichlorosilane (TCS) that is then
recycled to produce polysilicon.
APPROACHES TO HYDROGENATION
OF SILICON TETRACHLORIDE
Historically, STChydrogenation technology has
evolved through a number of stages, in line with the
progress in electronicsgrade silicon manufacturing
and in technology as a whole. The main problem lies
in the fact that the silicon–chlorine bonddissociation
energy is as high as 377 kJ/mol . Initially, it was
dealt with by using reducing agents to lower the bond
energy, whereas recently, we have seen the emergence
of plasma processes and of catalysts capable of direct
ing the hydrogenation along an energysaving route.
Today, the wide variety of methods for hydrogena
tion of STC to TCS may be divided into four groups,
each with its advantages and disadvantages:
(1) reducingagent hydrogenation;
(2) hightemperature hydrogenation;
(3) catalytic hydrogenation;
(4) plasma hydrogenation.
Reducingagent hydrogenation allows one to
choose from a wide range of agents and is compatible
with conventional process equipment. On the other
hand, it consumes much energy, requires byproduct
recycling, and contaminates the desired TCS with
reactants. These drawbacks keep the technique from
being employed on a commercial basis.
Hightemperature hydrogenation relies on the
equilibrium that is attained by a homogeneous system
of Si, H, and Cl under certain conditions. Hydrogena
tion of STC,
is accompanied by the dehydrochlorination of the
with the resultant silicon dichloride undergoing dis
Si + SiCl
and hydrogen reduction,
Si + 2HCl.
These are equilibrium reactions, the position of
equilibrium in each reaction depending on the tem
perature. Their respective equilibrium constants for
different temperatures  are listed in the table.
Approaches to Hydrogenation of Silicon Tetrachloride
in Polysilicon Manufacture
V. M. Ivanov and Yu. V. Trubitsin
Classical Private University, Zaporizhia, Ukraine
—A review of approaches to hydrogenation of silicon tetrachloride is presented. A byproduct of po
lysilicon manufacture, silicon tetrachloride is thus converted into trichlorosilane, which is then recycled to
reduce the production cost of polysilicon. Catalytic hydrogenation is identified as the most commercially
promising line of research and development.
polysilicon, silicon tetrachloride, hydrogenation, trichlorosilane, conversion efficiency, activa
tion, reducing agents, converter, plasma source, plasma chemical reaction.
AND TECHNOLOGY: SEMICONDUCTORS