I just went to a local computer store (holy sh1t those guys are smart!) and they told me about how Intel makes their Pentium 4 and Celeron Processors. OK, so they make a whole ton of Pentium 4 CPUs. They are arranged on shelves in a big warehouse, about 6x12 for each shelf thingy. The ones on opposite ends of the warehouse tend to be more defective, so these are taken off the racks and many of the features are disabled on these processors. These become Celeron Processors. The ones in the center, which tend to be less defective, are kept as they are and sold as Pentium 4s. :? Strange. I'm not making this up, it's fact.
1. A wafer is created from sand. Very long process, but it happens.
Probably you already know that, but I'll still post it here
The chemical process goes like this:
Si2O+Cl----->2Si+ClO (not sure about this one)--->>>95% pure Si, not enough for electronic devices
And after another process I gets 97% pure Si, just enough for electronics
Yeah, you got me goin', your first reaction is partially correct.... second reaction is not. (side note, the purest sand comes from the deserts of Saudi Arabia not only do they have us on oil, but they have us on sand too )....
SiO2 + C --> Si + CO2 (Si is not very pure).
Si + 3HCL --> SiHCl3 (Gas) + H2(gas, which is removed).
Single crystals are then grown by a method called CZ (Czochralski method). Essentially, you heat the silicon up to 1400 deg C, the melting point of silicon, form molten Si. Using a seed crystal literally tied to the end of a wire, you dip it in the molten Si briefly and begin pulling upward. As you pull Si adheres to the seed crystal and itself crystalizes. The purity levels in CZ silicon are typcially acceptable, but you can further purify Si by another method called Float Zone (FZ), this one is fascinating but too technical to go into details. When all is said and done, impurity levels in electronic grade silicon drop to the few part per million regime (PPM), typcially consisting of Fe, Al, Ca, Mg, Na, Zn.
The science of pulling a single crystal Si boule of high enough quality for 200 mm wafers is tough enough, 300 mm runs into a multitude of problems, the pull rate, the thermal cool rate, center to edge crystalization defects.... etc.