Oof. I'm not totally surprised but this is such a shame. We talk about how we want to bring more of this industry back to the US and then this news drops. Our priorities still aren't right.
how much does a 130nm fab cost? I think 45 and 65 would be better, but ideally the fab could create 6502 and "486" CPUs as well, as those will always be in high demand.
It's ~$20k to get on an MPW, for 65 you can double that.
If you're talking about how much it takes to build the fab: infinity dollars, nobody builds new fabs in these nodes anymore. Skywater is barely keeping its head above water as-is and that's mostly wafer services, not tapeouts.
Focused ion beam milling and electron microscopy machine is under $5m, but your fab output volume for pre-doped CMOS epitaxial grown core-stack wafers would never offset the capital investment. This is a very real machine, and no I don't have one available at this time. Probably it is for the greater good. lol =3
You could do it in 3nm (or any modern, in-demand node) on 300mm wafers. You could not do it in an ancient node where there's no commercial demand, on 200mm wafers the industry is slowly but surely superseding. These old nodes exist because the facilities were built 40+ years ago and there's just barely enough demand to keep them rolling.
The Skywater fab ran its first wafers in 1987. You could not build such a facility today for the same reason you couldn't build a large-scale factory for carbureted automobiles or CRT monitors. People still use these things, there's still a market for them, they're still serviced, but you could never find investors to build new production capacity.
Indeed, much of the mcu chip lines are still relatively old processes. If people need something radiation-hardened for space, than modern processes are inapplicable anyways due to smaller gate-size sensitivity etc.
Most firms are now fab-less chip companies, and given the production volume economics... the market leaves little room for "new" competition. =3