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Nikolaev Institute of Inorganic Chemistry

Siberian Branch of Russian Academy of Sciences

LITHIUM HYDRIDE TECHNOLOGY OF MONOSILANE PRODUCTION

Description

The technology is based on the developed method for obtaining monosilane from silicon tetrachloride by its interaction with lithium hydride. The method is new in the aspect of realization, since previously known method involved conversion of silicon tetrachloride into monosilane by lithium hydride in the salt melt medium.

In the known methods of silicon reduction by alkaline hydrides, no solution was provided to the problem of the formed salts: it is necessary to utilize them. In the proposed technological scheme, lithium chloride (LiCl) formed during reaction enters high-temperature electrolysis to obtain metal lithium, from which, in turn, lithium hydride is obtained, which is used for silicon tetrachloride conversion  into monosilane. This means that lithium works in recycle, which is a very important factor allowing one to decrease net cost of the final product.

Using this scheme, it is possible to process the available highly pure silicon tetrachloride, which is formed and accumulated in the production of silicon according to trichlorosilane technology, into monosilane by interaction with lithium hydride at a temperature about 300°С.

Cryogenic purification of the resulting monosilane allows obtaining it as a commercial product suitable for many applications in microelectronics, and for use in the production of high-purity polycrystalline silicon.

Technical and economical advantages:

  • recycling of the formed products (lithium chloride and unreacted chlorosilanes); improved ecological safety;
  • utilization of silicon tetrachloride accumulated in the trichlorosilane production of polysilicon, into monosilane or trichlorosilane.

Application areas

Microelectronics, production of solar silicon for Photoelectronic Receivers, production of high-purity polysilicon for monosilicon in power electronics.

Stage of development and place of usage

Experimental works have been performed to test the technology with the experimental laboratory equipment of the Novosibirsk Plant of Chemical Concentrates (NPCC); monosilane was obtained; its analysis proved its sufficient purity, even without purification. Technical and economical assessment was carried out; industrial set-up was designed to manufacture 20t of monosilane per year at the NPCC.

Cryogenic technology of monosilane purification from impurities has been developed for a set-up allowing one to obtain commercial monosilane with a purity not less than 99,99 vol.%

Enterprises of Zelenograd, Novosibirsk are ready to sell the product.

Patent situation

Method of obtaining and set-up are patented; patents granted in 2002 in Russian Federation.

Commercial proposals

Investment agreement for commercialization of the development, in the amount of 5 mln dollars.

Approximate cost

Net cost of monosilane manufactured according to this technology is lower by an order of magnitude than those of the known technologies.

Contacts

Nikolaev Institute of Inorganic Chemistry SB RAS
Acad. Lavrentyev ave., 3, Novosibirsk, Russia, 630090
Scientific secretary of Institute
Gerasko Olga Anatolievna, Doctor of chemical sciences
Phone: +7(383) 330-94-86
+7(383) 330-94-89
E-mail:
Web-page: http://www.niic.nsc.ru/en/