During drawing of single silicon crystals using the Czochralski technique, the silicon melt is contained in quartz glass crucibles. These can resist the high temperatures involved (approx. 1420°C) and ensure the extremely high degree of purity that is imperative for drawing single crystal.

Quartz glass crucibles are, in turn, supported by crucibles made of carbon fibre reinforced carbon (CFC). These can also be manufactured to maximum purity levels through high temperature treatment, avoiding contamination of the silicon melt. Utilisation temperatures of 1400 °C are standard for CFC materials. In combination with excellent thermal conductivity, CFC composites are therefore predestined for these tasks. An additional layer of pyrocarbon material can be applied to the CFC frame if required. Such CFC support crucibles are manufactured today with an inner diameter of up to approx. 80 cm (32 inches).