I think abusing a write-off electron microscope to side step the need for masks is also an interesting idea, however, I believe acquiring wafers of sufficient quality and depositing layers to be etched could be the bigger challenge here.
Hold on, if I had an electron microscope, can I just put in a decapped cheap large format photodiode under it, jack the beam current way up, and start etching trenches on it?
I don't think so: it's a microscope, not a synchrotron. :D
I meant "drawing" on a photoresist layer with a SEM and then wet-etching it. Also all silicon in a photodiode is doped, so the etched parts would be of little use, I believe.
And the clean environment as a whole. That's a massive investment and there are a million ways to mess that up.
> however, I believe acquiring wafers of sufficient quality and depositing layers to be etched could be the bigger challenge here
Definitely hard for a home fab but how about a community fab? Not necessarily a geographic community.
for making research grade devices you barely need a cleanroom
wafers are the easy bit.