> I've just learned that the ESP32 is manufactured on a TSMC 40mm process. That's essentially caveman tech.
But it's cheap, and MOQs are still achievable for mortals.
This is why.
There are way more reasons older litho processes persist beyond just them still making tons of money.
40nm for a microcontroller is rather impressive, given that the most are made with anything up to 180nm.
It takes more effort to design a chip with scaling down of geometries, lead times, and test samples are getting longer to get. Mask sets get more expensive. Less fabs are available to produce the chip. Some devices become unavailable at lower geometries.
Probably the only reason that line is still running would be validated long term stability products, or niche hardware designed with special application compatibility (E.G. radhard, higher end mil / aerospace concerns, maybe automotive).
Semiconductor tooling is rather expensive and I imagine that updating this to a more modern line would require overhauling and re-balancing many systems. It might help someone not familiar with the industry to imagine each technology node as an entirely new model of car.
There are some projects where people try to etch silicon in their garage, but the node they are targetting is from last century. Anything newer and you need toxic and corrosive chemicals, and increasingly exotic equipment. The yield isn't great either.
All those foundries based on old processes should be churning out at least equivalent (if not more capable) chips.
Heck, forget ESP32, is there a ESP8266 equivalent that's entirely made in the USA? Would love to use that instead - for many reasons.