Thought I might throw in some info (and this applies to photovoltaics as well)
Semiconductors (at least, the common, garden variety) are all made from silicon. In order to modify the electron levels in the silicon (i.e. to create donor or acceptor atoms) you gotta add 'dopants' like phosphorus, boron, arsenic and a few other nasties. These are all mixed in during production of the ingot, before sawing it into wafers.
The transistors in your mobile phone that do the transmission component are probably Gallium Arsenide (GaAs), again, nasty stuff.
The actual production process involves a number of steps, depending on the technology and process, usually involves a number of steps including a number of lithographic steps (using a UV photoresist - pretty nasty stuff), metal deposition and etching (sometimes HF is used for an etch step as it attacks silicon dioxide, but not silicon).
HF is a real nasty one since it is a weak acid by definition, and it goes straight through the skin to eat at the calcium in your bones (and you don't know it at the time, and die a horrible, painful death a little while later).
So there ya have it (what I can remember - it is late at night here!) of silicon. Most of the waste is VERY carefully controlled because of how toxic and dangerous it is.
I can dig up my notes, and I'm sure I'll find a few more!
