We'll likely never have "affordable" photolithography, but electron beam lithography will become obtainable in my lifetime (and already is, DIY, to some degree.)
Making at home transistors, or even small-scale integrated circuits is not exceedingly difficult.
However, making at home a useful microcontroller or FPGA would require not only an electron-beam lithography machine, but also a ion-implantation machine, a diffusion furnace, a plasma-etch machine, a sputtering machine and a lot of other chemical equipment and measurement instruments.
All the equipment would have to be enclosed in a sealed room, with completely automated operation.
A miniature mask-less single-wafer processing fab could be made at a cost several orders of magnitude less than a real semiconductor fab, but the cost would still be of many millions of $.
With such a miniature fab, one might need a few weeks to produce a batch of IC's worth maybe $1000, so the cost of the equipment will never be recovered, which is why nobody does such a thing for commercial purposes.
In order to have distributed semiconductor fabs serving small communities around them, instead of having only a couple of fabs for the entire planet, one would need a revolution in the fabrication of the semiconductor manufacturing equipment itself, like SpaceX has done for rockets.
Only if the semiconductor manufacturing equipment would be the result of a completely automated mass production, which would reduce its cost by 2 or 3 orders of magnitude, affordable small-scale but state-of-the-art fabs would be possible.
But such an evolution is contrary to everything that the big companies have done during the last 30 years, during which all smaller competitors have been eliminated, the production has become concentrated in quasi-monopolies and for the non-consumer products the companies now offer every year more and more expensive models, which are increasingly affordable only for other big companies and not for individuals or small businesses.
> With such a miniature fab, one might need a few weeks to produce a batch of IC's worth maybe $1000
Maybe?
Another point of view might be that in a few weeks you could produce a batch of ICs you can actually trust, that would be several orders of magnitude more valuable than the $1000 worth of equivalents from the untrusted global supply chain.
> However, making at home a useful microcontroller or FPGA would require not only an electron-beam lithography machine, but also a ion-implantation machine, a diffusion furnace, a plasma-etch machine, a sputtering machine and a lot of other chemical equipment and measurement instruments.
That ASU NanoFab has indeed almost everything that is needed.
It is weird that they do not have any ion implantation machine, because there are devices that are impossible to make without it. Even for simple MOS transistors, I am not aware of any other method for controlling the threshold voltage with enough precision. Perhaps whenever they need ion implantation they send the wafers to an external fab, with which they have a contract, to be done there.
Still, I find it hard to believe that all the equipment that they have costs less than 10 million $, unless it is bought second hand. There is indeed a market for slightly obsolete semiconductor manufacturing equipment, which has been replaced in some first tier fabs and now it is available at significant discounts for those who are content with it.
https://en.wikipedia.org/wiki/Moore%27s_second_law: “Rock's law or Moore's second law, named for Arthur Rock or Gordon Moore, says that the cost of a semiconductor chip fabrication plant doubles every four years”
Wafer machines from the 1970s could be fairly cheap today, if there were sufficient demand for chips from the 1970s (~1MHz, no power states, 16 bit if you’re lucky, etc), but that trend would have to stop and reverse significantly for affordable wafer factories for modern hardware to be a thing.
Peter Norvig, Fabrice Bellard, etc. The list of ultra smart people is quite long. A friend of mine thought he was pretty smart (and I would have happily agreed with him). Then he went to work for Google (early days). It didn't take long for him to realize that the only reason he seemed very smart was that he simply wasn't seeing a large enough slice of humanity.
"The principle of evidence-based trust was at work in our decision to implement Precursor’s brain as an SoC on an FPGA, which means you can compile your CPU from design source and verify for yourself that Precursor contains no hidden instructions or other backdoors. Accomplishing the equivalent level of inspection on a piece of hardwired silicon would be…a rather expensive proposition. Precursor’s mainboard was designed for easy inspection as well, and even its LCD and keyboard were chosen specifically because they facilitate verification of proper construction with minimal equipment."
In addition to what the other comments have already highlighted, there's also the fact that you'd be back to using extremely opaque, even less "open source" hardware than regular CPUs/MCUs. Almost every FPGA that could even conceivably be used to run general purpose software is locked behind super proprietary stacks
