Tungsten Silicide (WSi2)-Powder

Characteristic

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

Chemical formula:WSi2

Molar mass:240.011 g/mol

Appearance:blue-gray tetragonal crystals

Density:9.3 g/cm³

Melting point:2160 °C (3,920 °F; 2,430 K)

Solubility in water:insoluble

Application

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 is also of value towards use in microelectromechanical systems, where it is mostly applied as thin films for fabrication of microscale circuits. For such purposes, films of tungsten silicide can be plasma-etched using e.g. nitrogen trifluoride gas.

WSi₂ performs well in applications as oxidation-resistant coatings. In particular, in similarity to Molybdenum disilicide, MoSi₂, the high emissivity of tungsten disilicide makes this material attractive for high temperature radiative cooling, with implications in heat shields.