Trichlorosilane is an

inorganic compound In chemistry, an inorganic compound is typically a chemical compound that lacks carbon–hydrogen bonds, that is, a compound that is not an organic compound. The study of inorganic compounds is a subfield of chemistry known as '' inorganic chemist ...

with the formula HCl₃Si. It is a colourless, volatile liquid. Purified trichlorosilane is the principal precursor to ultrapure silicon in the

semiconductor A semiconductor is a material which has an electrical resistivity and conductivity, electrical conductivity value falling between that of a electrical conductor, conductor, such as copper, and an insulator (electricity), insulator, such as glas ...

industry. In water, it rapidly decomposes to produce a

siloxane A siloxane is a functional group in organosilicon chemistry with the Si−O−Si linkage. The parent siloxanes include the oligomeric and polymeric hydrides with the formulae H(OSiH2)''n''OH and (OSiH2)n. Siloxanes also include branched compoun ...

polymer while giving off

hydrochloric acid Hydrochloric acid, also known as muriatic acid, is an aqueous solution of hydrogen chloride. It is a colorless solution with a distinctive pungent smell. It is classified as a strong acid Acid strength is the tendency of an acid, symbol ...

. Because of its reactivity and wide availability, it is frequently used in the synthesis of silicon-containing organic compounds.

Production

Trichlorosilane is produced by treating powdered

metallurgical grade silicon Silicon is a chemical element with the symbol Si and atomic number 14. It is a hard, brittle crystalline solid with a blue-grey metallic luster, and is a tetravalent metalloid and semiconductor. It is a member of group 14 in the periodic tab ...

with blowing

hydrogen chloride The compound hydrogen chloride has the chemical formula and as such is a hydrogen halide. At room temperature, it is a colourless gas, which forms white fumes of hydrochloric acid upon contact with atmospheric water vapor. Hydrogen chloride ga ...

at 300 °C. Hydrogen is also produced, as described in the

chemical equation A chemical equation is the symbolic representation of a chemical reaction in the form of symbols and chemical formulas. The reactant entities are given on the left-hand side and the product entities on the right-hand side with a plus sign between ...

: :Si + 3 HCl → HCl₃Si + H₂ Yields of 80-90% can be achieved. The main byproducts are

silicon tetrachloride Silicon tetrachloride or tetrachlorosilane is the inorganic compound with the formula SiCl4. It is a colourless volatile liquid that fumes in air. It is used to produce high purity silicon and silica for commercial applications. Preparation Silic ...

(

chemical formula In chemistry, a chemical formula is a way of presenting information about the chemical proportions of atoms that constitute a particular chemical compound or molecule, using chemical element symbols, numbers, and sometimes also other symbols, ...

SiCl₄),

hexachlorodisilane Hexachlorodisilane is the inorganic compound with the chemical formula Si2Cl6.Simmler, W. "Silicon Compounds, Inorganic", ''Ullmann's Encyclopedia of Industrial Chemistry'', Weinheim: Wiley-VCH. It is a colourless liquid that fumes in moist air. ...

(Si₂Cl₆) and

dichlorosilane Dichlorosilane, or DCS as it is commonly known, is a chemical compound with the formula H2SiCl2. In its major use, it is mixed with ammonia (NH3) in LPCVD chambers to grow silicon nitride in semiconductor processing. A higher concentration of DCS ...

(H₂SiCl₂), from which trichlorosilane can be separated by

distillation Distillation, or classical distillation, is the process of separation process, separating the components or substances from a liquid mixture by using selective boiling and condensation, usually inside an apparatus known as a still. Dry distilla ...

It is also produced from silicon tetrachloride: :Si + 3 SiCl₄ + 2 H₂ → 4 HCl₃Si

Applications

Trichlorosilane is the basic ingredient used in the production of purified

polysilicon Polycrystalline silicon, or multicrystalline silicon, also called polysilicon, poly-Si, or mc-Si, is a high purity, polycrystalline form of silicon, used as a raw material by the solar photovoltaic and electronics industry. Polysilicon is produce ...

. :HCl₃Si → Si + HCl + Cl₂

Ingredient in hydrosilylation

Via

hydrosilylation Hydrosilylation, also called catalytic hydrosilation, describes the addition of Si-H bonds across unsaturated bonds."Hydrosilylation A Comprehensive Review on Recent Advances" B. Marciniec (ed.), Advances in Silicon Science, Springer Science, 2009 ...

, trichlorosilane is a precursor to other useful organosilicon compounds: :RCH=CH₂ + HSiCl₃ → RCH₂CH₂SiCl₃ Some useful products of this or similar reactions include

octadecyltrichlorosilane Octadecyltrichlorosilane (ODTS or ''n''-octadecyltrichlorosilane) is an organosilicon chemical. It is used in semiconductor industry to form self-assembled monolayer thin films on silicon dioxide substrates. Its structural chemical formula is CH3 ...

(OTS), perfluoroctyltrichlorosilane (PFOTCS), and perfluorodecyltrichlorosilane (FDTS). These reagents used in surface science and nanotechnology to form

Self-assembled monolayer Self-assembled monolayers (SAM) of organic molecules are molecular assemblies formed spontaneously on surfaces by adsorption and are organized into more or less large ordered domains. In some cases molecules that form the monolayer do not interact ...

s. Such layers containing fluorine decrease surface energy and reduce sticking. This effect is usually exploited as coating for

MEMS Microelectromechanical systems (MEMS), also written as micro-electro-mechanical systems (or microelectronic and microelectromechanical systems) and the related micromechatronics and microsystems constitute the technology of microscopic devices, ...

and microfabricated stamps for a nanoimprint lithography (NIL) and in

injection molding Injection moulding (U.S. spelling: injection molding) is a manufacturing process for producing parts by injecting molten material into a mould, or mold. Injection moulding can be performed with a host of materials mainly including metals (for ...

tools.

Organic synthesis

Trichlorosilane is a reagent in the conversion of benzoic acids to toluene derivatives. In the first step of a two-pot reaction, the carboxylic acid is first converted to the trichlosilylbenzyl compound. In the second step, the benzylic silyl derivative is converted to the toluene derivative with base.

Safety

It reacts violently with water (H₂O) producing SiO₂,

chlorine Chlorine is a chemical element with the Symbol (chemistry), symbol Cl and atomic number 17. The second-lightest of the halogens, it appears between fluorine and bromine in the periodic table and its properties are mostly intermediate betwee ...

(Cl) gas,

(HCl) and heat. According to a safety datasheet, spills of trichlorosilane may be neutralized by using

NaOH Sodium hydroxide, also known as lye and caustic soda, is an inorganic compound with the formula NaOH. It is a white solid ionic compound consisting of sodium cations and hydroxide anions . Sodium hydroxide is a highly caustic base and alkali ...

or NaHCO₃, per one or two part of trichlorosilane.{{Cite report , url=https://www.nj.gov/health/eoh/rtkweb/documents/fs/1903.pdf , title=Hazardous Substance Fact Sheet: Trichlorosilane , date=October 2010 , publisher=New jersey department of health

References

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