[wrycoder]

They are not really that toxic. You do have to have a chemistry background and use a fume hood and a process sink with acid neutralization capability, like you find in many chem labs.

Good dopant choices would be phosphorus oxychloride and oxidized boron nitride wafers.

As I recollect, he started with silicon wafers with an epitaxy layer. He then did the usual oxidations, diffusions, and metallization, along with all the photolithographic steps. No small feat!

[geomark]

Ok. I was never a process guy, but worked with some back in the day and they told me that one of their phosphorus sources was phosgene gas.

[wrycoder]

Silane, phosphene, and diborane gases are used to form epitaxial layers on silicon wafers. Those are truly dangerous gases. However, a simple wafer process using the reagents I mentioned can produce very credible ICs, if one buys the epi wafers.