PFCs are used by the semiconductor industry primarily for in-situ chamber cleaning of CVD/PECVD tools and minor volume for wafer etching.
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.
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.
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 (The SF6 ReUse Program. A Case Study - DC Lauzon. San Diego CA 2002), allows SF6 to be used in an environmentally friendly manner and to be kept in a closed cycle.