From Sand to Silicon
Every electronic device runs on silicon chips that begin as ordinary sand. In nature, silicon is locked up in quartz (silicon dioxide, SiO₂) sand – about 95% of common quartz sand is SiO₂. To make chips, manufacturers first purify this sand. They heat quartz with carbon in a furnace, driving off oxygen and leaving raw metallurgical-grade silicon. Next, a chemical refining step (the Siemens process) turns this into polysilicon : ultra-pure polycrystalline silicon with impurity levels below a few parts per billion en.wikipedia.org . These purified silicon rods (polysilicon) are the feedstock for crystal growth. _____________________________________________________________________________ Crystal Growth: Pulling a Single Crystal : The polysilicon feedstock is melted and a tiny seed crystal is slowly pulled upward, in what’s called the Czochralski process en.wikipedia.org . As the seed emerges, it drags a large, cylindrical single-crystal silicon boule (ingot) out of ...