要約
No other chain multiplies value like this one. Quartz worth tens of dollars a tonne becomes polysilicon worth tens of dollars a kilogram, then a wafer, then a chip whose value per gram exceeds almost anything else manufactured.
段階ごと
Quartz and quartzite
Silicon dioxide is the most common compound in the crust, but deposits pure enough for crucibles are rare and closely held.
Carbothermic reduction
Quartz and carbon are heated in an arc furnace to about 2,000 C, producing metallurgical-grade silicon at roughly 99%.
Polysilicon
The Siemens process converts silicon to trichlorosilane, distils it and redeposits it — reaching eleven nines for semiconductors.
注記: This step is essentially electricity turned into purity.
Monocrystalline ingot and wafer
A seed crystal is pulled slowly from a melt held in a high-purity quartz crucible, then sliced and polished.
注記: The crucible is consumed each time — which is what makes crucible-grade quartz strategic.
Fabricated chip
Hundreds of deposition, lithography and etch steps build transistors and copper wiring on the wafer.
Everything electronic
