Tungsten disilicide

Tungsten disilicide
IUPAC name Tungsten disilicide
Identifiers
CAS number	12039-88-2 Y
Properties
Molecular formula	WSi2
Molar mass	240.01 g/mol
Appearance	blue-gray tetragonal crystals
Density	9.3 g/cm3
Melting point	2160°C
Solubility in water	insoluble
Hazards
EU Index	not listed
NFPA 704	0 1 0
Flash point	Non-flammable
Related compounds
Other anions	Tungsten carbide Tungsten nitride
Other cations	Molybdenum disilicide
Y (verify) (what is: Y/N?) Except where noted otherwise, data are given for materials in their standard state (at 25 °C, 100 kPa)
Infobox references

Tungsten disilicide, or just tungsten silicide (WSi₂) is an inorganic compound, a silicide of tungsten. It is an electrically conductive ceramic material.

Chemistry

Tungsten silicide can react violently with substances such as strong acids, fluorine, oxidizers, and interhalogens.

Applications

It is used in microelectronics as a contact material, with resistivity 60–80 μΩ cm; it forms at 1000 °C. It is often used as a shunt over polysilicon lines to increase their conductivity and increase signal speed. Tungsten silicide layers can be prepared by chemical vapor deposition, e.g. using monosilane or dichlorosilane with tungsten hexafluoride as source gases. The deposited film is non-stoichiometric, and requires annealing to convert to more conductive stoichiometric form. Tungsten silicide is a replacement for earlier tungsten films. Tungsten silicide is also used as a barrier layer between silicon and other metals, e.g. tungsten.

Tungsten silicide also finds use in microelectromechanical systems and for oxidation-resistant coatings.

Films of tungsten silicide can be plasma-etched using e.g. nitrogen trifluoride gas.