Production of silicon wafers begins with the manufacture of a single silicon crystal. A variety of processes can be selected here, the most well-known being the Czochralski method. Large ingots are drawn out of the silicon melt utilising a seed crystal. This is contained in a quartz crucible which in turn is supported by a CFC crucible. Ultra-pure graphite heating elements fixed with CFC screws are used to heat the CFC crucible. The excellent thermal conductivity of graphite and extremely high purity are basic prerequisites for this application.

The graphite components are cleaned for this purpose in special reactors through high-temperature treatment, removing residual impurities smaller than 10 ppm. All further process steps (or packaging) are realised under clean room conditions to avoid further contamination. The largest graphite heating elements currently utilised in standard systems have a diameter of up to 1000 mm.