Trichlorosilane
Encyclopedia
Trichlorosilane is a chemical compound
containing silicon
, hydrogen
, and chlorine
. At high temperatures, it decomposes to produce silicon, and therefore purified trichlorosilane is the principal source of ultrapure silicon in the semiconductor
industry. In water, it rapidly decomposes to produce a silicone
polymer while giving off hydrochloric acid
. Because of its reactivity and wide availability, it is frequently used in the synthesis of silicon-containing organic
compounds.
through a bed of silicon powder at 300°C. There, they combine to make trichlorosilane and hydrogen according to the chemical equation
A properly designed reactor can achieve a yield of 80-90% trichlorosilane. The major byproducts are silicon tetrachloride
(chemical formula
SiCl4), hexachlorodisilane (Si2Cl6), and dichlorosilane
(H2SiCl2), from which trichlorosilane can be separated by distillation
.
The reverse process is used in the production of silicon of higher purity.
Chemical compound
A chemical compound is a pure chemical substance consisting of two or more different chemical elements that can be separated into simpler substances by chemical reactions. Chemical compounds have a unique and defined chemical structure; they consist of a fixed ratio of atoms that are held together...
containing silicon
Silicon
Silicon is a chemical element with the symbol Si and atomic number 14. A tetravalent metalloid, it is less reactive than its chemical analog carbon, the nonmetal directly above it in the periodic table, but more reactive than germanium, the metalloid directly below it in the table...
, hydrogen
Hydrogen
Hydrogen is the chemical element with atomic number 1. It is represented by the symbol H. With an average atomic weight of , hydrogen is the lightest and most abundant chemical element, constituting roughly 75% of the Universe's chemical elemental mass. Stars in the main sequence are mainly...
, and chlorine
Chlorine
Chlorine is the chemical element with atomic number 17 and symbol Cl. It is the second lightest halogen, found in the periodic table in group 17. The element forms diatomic molecules under standard conditions, called dichlorine...
. At high temperatures, it decomposes to produce silicon, and therefore purified trichlorosilane is the principal source of ultrapure silicon in the semiconductor
Semiconductor
A semiconductor is a material with electrical conductivity due to electron flow intermediate in magnitude between that of a conductor and an insulator. This means a conductivity roughly in the range of 103 to 10−8 siemens per centimeter...
industry. In water, it rapidly decomposes to produce a silicone
Silicone
Silicones are inert, synthetic compounds with a variety of forms and uses. Typically heat-resistant and rubber-like, they are used in sealants, adhesives, lubricants, medical applications , cookware, and insulation....
polymer while giving off hydrochloric acid
Hydrochloric acid
Hydrochloric acid is a solution of hydrogen chloride in water, that is a highly corrosive, strong mineral acid with many industrial uses. It is found naturally in gastric acid....
. Because of its reactivity and wide availability, it is frequently used in the synthesis of silicon-containing organic
Organic chemistry
Organic chemistry is a subdiscipline within chemistry involving the scientific study of the structure, properties, composition, reactions, and preparation of carbon-based compounds, hydrocarbons, and their derivatives...
compounds.
Production
Industrially, trichlorosilane is produced by blowing hydrogen chlorideHydrogen chloride
The compound hydrogen chloride has the formula HCl. At room temperature, it is a colorless gas, which forms white fumes of hydrochloric acid upon contact with atmospheric humidity. Hydrogen chloride gas and hydrochloric acid are important in technology and industry...
through a bed of silicon powder at 300°C. There, they combine to make trichlorosilane and hydrogen according to the chemical equation
Chemical equation
A chemical equation is the symbolic representation of a chemical reaction where the reactant entities are given on the left hand side and the product entities on the right hand side. The coefficients next to the symbols and formulae of entities are the absolute values of the stoichiometric numbers...
- Si + 3 HCl → HSiCl3 + H2
A properly designed reactor can achieve a yield of 80-90% trichlorosilane. The major byproducts are silicon tetrachloride
Silicon tetrachloride
Silicon tetrachloride 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:...
(chemical formula
Chemical formula
A chemical formula or molecular formula is a way of expressing information about the atoms that constitute a particular chemical compound....
SiCl4), hexachlorodisilane (Si2Cl6), and dichlorosilane
Dichlorosilane
Dichlorosilane , or DCS as it is commonly known, is usually mixed with ammonia in LPCVD chambers to grow silicon nitride in semiconductor processing.A higher concentration of DCS:NH3 Dichlorosilane (H2SiCl2), or DCS as it is commonly known, is usually mixed with ammonia (NH3) in LPCVD chambers to...
(H2SiCl2), from which trichlorosilane can be separated by distillation
Distillation
Distillation is a method of separating mixtures based on differences in volatilities of components in a boiling liquid mixture. Distillation is a unit operation, or a physical separation process, and not a chemical reaction....
.
The reverse process is used in the production of silicon of higher purity.