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.