A few years ago, someone had the bright idea of sticking a high-resolution LCD screen in front of an ultraviolet backlight, and thus was the practical, low-cost photoresin 3D printer born.
Resolution improved, performance improved, and now I have an affordable Elegoo Mars 2 Pro with 50µm pixel pitch, suitable for creating plastic parts in quite complex shapes with a fair amount of precision.
So where do we go from there?
Thomas Sanladerer points out that you can use one of these to expose the photoresist on etch-your-own printed circuit boards. D'OH! It's so obvious... once someone points it out. And it could come to pass that, someday, I'll be wanting to make some single-sided boards for one reason or another.
But, this gets me thinking. If you have a UV source, and a computerized mask with 50µm pixel pitch, just how good a lens do you need to shrink the image down to where you could expose the photoresist on a 1970s-tech integrated circuit? Apparently early 4000-series CMOS used 20µm geometry, and later generations use 10µm, so that doesn't seem like much of a stretch. Might even be extended to whatever geometry was used for the 6502!
It'd need a good fixture for consistent wafer positioning, but that shouldn't be all that difficult. And a fair-decent clean room, which is more of a challenge.
Then there are the details of coating, etching, metallization, doping... there are people out there with home sputtering setups, but etching and doping (at least, for the methods in use in the 1970s) tend to involve materials that are on sane people's NOPE! lists. And local authorities might get soggy and hard to light if they thought you had that stuff in your garage.
... I seem to recall that Jeri Ellsworth was trying to set up a semiconducter fab operation in her garage a few years back. Dunno how far she got with that. And it could be that plasma etching and ion implantation would reduce the need for insanely dangerous chemicals. Maybe. Do I look like a semi fab guru?
If you say I look like anything less than a totally fab guru, I'll take umbrage.
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