Explosion in a silicon crystal growing reactor

The incident happened in an a reactor for silicon crystal growing of electronic-grade. An explosion was located in scrubber tank of the facility, due to an increase of hydrogen in the entrainment separator.

[Zalosh and Short, 1978]

The increase in hydrogen concentration was triggered by the shutdown of the scrubber including the exhaust fan. Therefore the ROOT CAUSE could be tentatively attributed to an inadequate safety design, unable to guarantee continuous availablity of critical components (in this case, the capacity to vent)

scrubber tanl

DESCRIPTION OF THE PROCESS
To produce epitaxial silicon, a silicon-containing gas, such as trichlorosilane (SiHCl3) is introduced into the reaction chamber along with a carrier gas, usually hydrogen as ultra-high-purity carrier gas and chemical reducing agent. The reaction process gases are then sent to a scrubber, to capture and neutralize hazardous, toxic, and corrosive gases produced during the epitaxial deposition process (mainly hydrochloric acid HCl, Silanes SiH₄, rest of chlorosilanes, silicon oxides (particulates rest of the dopant precursors, such as arsine AsH₃ and phosphine PH₃). These substances are separated from the gas stream by reactive chemical liquids, usually an acidic or basic aqueous solution, and collected in a scrubber tank, while hydrogen is sent to the venting system.