Silicon is the chemical element with atomic number 14, chemical symbol Si. It is one of the most frequent elements. 15% per weight of the globe is silicon, 25% in the crust. Only oxygene has a bigger amount. In nature silicon does not exist in elementary form but only in form of componds. The most important compound is mineralic SiO2. This is the most essential component of granite, sand and sandstone. The pure SiO2-mineral is designated quartz. In its pure form it can be used for quartz glas production. Generally SiO2 is the main component of glas.

The silicon atom with its 4 valence elctrons has similar possibilities to form compounds and crystals like carbon. In its elementary form silicon is a semimetal or semiconductor, effectively it is by far the most essential commercial semiconductor. A most important reason is its abbility to form extremely large single crystals.

Plasma technology is applied for many different types of silicon treatment, most particularly for etching to create geometrical structures. Often Fluorine compounds are used for etching such as sulfur hexafluoride SF6 or tetrafluormethane CF4. Additionally circuit paths are applied by fotolithographic methods and protective coatings by plasma polymerisation.

Ion etching
Reactive Ion Etching (RIE) enables for anisotropic etching with high etching ratren.
Semiconductor wafers which are used for the fabrication of electronic devices are thin cuts of large cylindric silicon single crystals.