Editing Silicon on sapphire (section)

{{About|the manufacturing process|the song "Silicone on Sapphire" by the Clash|Sandinista!}}

'''Silicon on sapphire''' ('''SOS''') is a [[Epitaxy|hetero-epitaxial]] process for [[metal–oxide–semiconductor]] (MOS) [[integrated circuit]] (IC) [[semiconductor device fabrication|manufacturing]] that consists of a thin layer (typically thinner than 0.6&nbsp;[[μm]]) of [[silicon]] grown on a [[sapphire]] ({{chem|Al|2|O|3}}) [[wafer (electronics)|wafer]]. SOS is part of the [[silicon-on-insulator]] (SOI) family of [[CMOS]] (complementary MOS) technologies.

Typically, high-purity artificially grown sapphire crystals are used. The silicon is usually deposited by the decomposition of [[silane]] gas ({{chem|SiH|4}}) on heated sapphire substrates. The advantage of sapphire is that it is an excellent [[Electrical insulation|electrical insulator]], preventing stray [[Current (electricity)|currents]] caused by radiation from spreading to nearby circuit elements. SOS faced early challenges in commercial manufacturing because of difficulties in fabricating the very small [[transistor]]s used in modern high-density applications.  This is because the SOS process results in the formation of dislocations, twinning and stacking faults from [[crystal lattice]] disparities between the sapphire and silicon. Additionally, there is some [[aluminum]], a p-type [[dopant]], contamination from the substrate in the silicon closest to the interface.