SF₆ as a process gas in the semiconductor industry

To manufacture wafers, the semiconductor industry requires gaseous fluorinated compounds, silanes (e.g. SiH₄) and doping gases (e.g. AsH₃, PH₃). Wafers consist of high-purity silicon and are the basic building blocks for all semiconductor components.

Essentially, the high-purity gases (e.g. SF₆) are used as etching gases for plasma etching or as cleaning gases to clean the chambers after the etching process.

Gases for plasma etching
  
Etching produces structures on the surface of the silicon. In the wafer manufacturing process, fluorine ions and radicals are needed to etch the silicon. Structures with a width of 0.15 µm or smaller can be created with this method.

Chamber cleaning after the etching process
  
When the silicon layers are being applied, a fraction of the silicon does not end up on the wafer, but is deposited in the CVD (Chemical Vapour Deposition) chamber. To prevent the wafers becoming contaminated by these deposits in downstream processes, the chambers are cleaned at defined intervals. The SF₆ decomposed by the plasma, allows the chambers to be cleaned. Consistent use of retention and cleaning systems, as well as the SF₆ ReUse Concept, allows SF₆ to be used in an environmentally friendly manner and to be kept in a closed cycle.

 

• Electrical engineering

• Applications in the electrical engineering
• High-voltage switchgear and switching stations
• SF₆ for the Itaipú hydroelectric station
• Gas insulated transmission line (GIL)
• Medium-high-voltage switchgear
• High-voltage cables and tubular transmission lines
• Transformers
• Other high-voltage applications
• SF₆ for the Vivitron accelerator