Posted: Jun 21, 2022 8:01 am
by Spearthrower
Stuff humans can do is insane.

Monocrystalline silicon is generally created by one of several methods that involve melting high-purity, semiconductor-grade silicon (only a few parts per million of impurities) and the use of a seed to initiate the formation of a continuous single crystal. This process is normally performed in an inert atmosphere, such as argon, and in an inert crucible, such as quartz, to avoid impurities that would affect the crystal uniformity.

The most common production technique is the Czochralski method, which dips a precisely oriented rod-mounted seed crystal into the molten silicon. The rod is then slowly pulled upwards and rotated simultaneously, allowing the pulled material to solidify into a monocrystalline cylindrical ingot up to 2 meters in length and weighing several hundred kilograms. Magnetic fields may also be applied to control and suppress turbulent flow, further improving the uniformity of the crystallization.[3] Other methods are zone melting, which passes a polycrystalline silicon rod through a radiofrequency heating coil that creates a localized molten zone, from which a seed crystal ingot grows, and Bridgman techniques, which move the crucible through a temperature gradient to cool it from the end of the container containing the seed.[4] The solidified ingots are then sliced into thin wafers during a process called wafering. After post-wafering processing, the wafers are ready for use in fabrication.

Compared to the casting of polycrystalline ingots, the production of monocrystalline silicon is very slow and expensive. However, the demand for mono-Si continues to rise due to the superior electronic properties—the lack of grain boundaries allows better charge carrier flow and prevents electron recombination[5]—allowing improved performance of integrated circuits and photovoltaics.