[KirillPanov]

Hey, I admire your spirit and enthusiasm.

However, one thing to keep in mind is that below 500nm a lot of the chemicals are extremely toxic and not the kind of thing that garage hackers are qualified to handle in an environmentally safe manner.

Arsenic, phosphene gas, hydrogen fluoride, nasty solvents. I build a lot of crazy stuff in my shop, but I don't even trust myself to dispose of these correctly. If makers like myself get involved in this we're going to end up with a lot of new superfund sites. In residential neighborhoods.

And then of course there's the ion implanter, which none of the fab employees want to spend much time around...

[wallacoloo]

I’m not hooked on building desktop CPUs at home or anything. It could be 3 um, 1 MHz and I’d be happy. It doesn’t even have to be semiconductors. We had vacuum tubes and core memory before transistors. The modern fab is optimized for density, perf, and power. Prioritize ease of fabrication and maybe you get a process or substrate that looks radically different from today’s commercial fabs.

Or maybe we adopt a 500 nm node and stop there :-)