Main applications

PFCs are used by the semiconductor industry primarily for in-situ chamber cleaning of CVD/PECVD tools and minor volume for wafer etching.

SF₆ uses 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.

Technical and safety aspects

Technical

The gas is converted into radicals in plasma with a typical utilisation of 20 to 70 %. The unconverted portion is intended to be reacted with off-gas treatment methods which are either commercially available or still under development.

Safety aspects

PFCs are selected for these applications for simply process needs, the need for Fluor radicals. The favourable product efficiency, combined with an easy handling procedure due to the non-toxic classification of PFCs are key.

Recovery and recycling

PFC abatement methods showing the most promise for this, including combustion, plasma, and catalytic methods. The specific production process is basically determining the PFC-gas to be used, with very little flexibility.

The World Semiconductor Council committed to proactively reduce PFC emission from their manufacturing processes. Accordingly, the regional organisations reached consensus to reduce the aggregate absolute emissions by 10% or greater by 2010 versus 1995. This reduction goal will be implemented in each region and a monitoring process will be implemented in order to provide regulatory transparency about the progress. This is a "stretch-goal" as a 10% absolute reductions correlates to a +95% relative reduction level taking the high average growth factor into account.