[gregpawin]

If anyone has some questions about semiconductor processing... please ask.

[Mitch]

yeah, when is your article coming out about the topic.  

[Corvettaholic]

Good article Greg, next step is.. how does that silicon ingot become a transistor? Like the kind at radio shack.

[jdurg]

Very nice, succinct article.  It's pretty neat how sand is turned into hyperpure silicon.  I've got some silicon samples in my element collection at various stages of purity, and it's amazing how much different 99% pure is from 99.9999% pure silicon.  

[gregpawin]

thanks guys.  Jdurg do you have a single crystal sample or polycrystalline?

[jdurg]

Yeah.  I have many wafers of nearly 100% pure silicon.  When I get a chance, I'll take a picture of them and send them your way.  

[Scratch-]

I have a Q...   What impurities do they put in the silicon to create transistors.

[gregpawin]

Well, there are a few ways to put impurities, or dope, silicon.  Either add these doping agents staight into the melt with the melted silicon, or by ion implantation.  Ion implantation's kinda cool because with the energies involved, we're talking about particle collider energies to get elements like phosphorous, arsenic, or boron to shoot into the silicon.  They're acurrate enough so that when we shoot oxygen, we can actually build an oxide layer of silicon for insulating purposes a good deal under the surface of the silicon.

Typically we use boron and phosphous, but we can also use Al, Ga, In, O, C, As, Sb, Te, Li, Cu, Au (those last two are probably used for other reasons other than making extra electrons and holes) and probably a few other ones.