Why Tungsten Hexafluoride Needs Purification

Tungsten hexafluoride is a binary compound of tungsten and fluorine with the chemical formula WF₆. Among the tungsten fluorides, tungsten hexafluoride (WF₆) is the only stable and industrially produced variety.

The main use of tungsten hexafluoride is used to prepare high purity tungsten powder and as a raw material for metal tungsten chemical vapor deposition (CVD) process. In particular, WSi₂ can be used as a wiring material for large scale integrated circuits. A composite coating of tungsten and rhenium is produced by a mixed-metal CVD process for the production of x-ray emitting electrodes and solar absorbers. In addition, tungsten hexafluoride can also be used in the electronics industry, semiconductor electrodes and conductive paste raw materials, it can be said that tungsten hexafluoride in high-tech fields have an irreplaceable role.

At present, there are three methods commonly used in the synthesis of tungsten hexafluoride. The first is to produce tungsten hexafluoride through the direct reaction of fluorine gas and tungsten. The second is the direct reaction of tungsten and three fluorinated nitrogen (NF₃) to produce tungsten hexafluoride. The third method is to produce tungsten hexafluoride by reaction with tungsten, halogen and HF. In a real sense, the tungsten hexafluoride made by the three methods can only be regarded as primary products. It still contains a lot of impurities, the purity is also difficult to meet the industrial requirements, therefore, for purification of tungsten hexafluoride purification is especially necessary.

The industrial demand indeed tungsten hexafluoride purity requirements are high, generally not less than 99.999% (3N). Therefore, the tungsten hexafluoride to be re-purification purification, there are many purification methods, there are: hydrofluoric acid purification, carbon purification, tungsten hexachloride replacement and so on.

The industrial demand indeed tungsten hexafluoride purity requirements are high, generally not less than 99.999% (3N). Therefore, tungsten hexafluoride purification needs to be purified and there are many ways, mainly are: Continuous distillation method, carbon purification method, tungsten hexachloride replacement method and so on. The above methods have their own advantages, the purity of less than 99.9% of tungsten hexafluoride, water content of less than 1ppmv, HF content of less than 1000ppmv primary tungsten hexafluoride purified to 99.999% or more, making it suitable for the needs of the semiconductor industry.

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