>> For those considering exploring some of these steps in their own garage -- the chemistry is dangerous, perhaps HF in particular, as it doesn't hurt, it just kills you a few hours later.
I was hoping that with 50 years of development behind us, the home fabricators could use less complex methods and less hazardous chemicals. In other words, can the folks who lived it help people like this by saying "If we had to do it over, I'd go about it like...."
Any suggestions? If you had to reboot the chip fab business on a budget what would be a more practical approach?
I used to work in a fab. As far as I know, there's no acceptable way to remove native oxide without HF. We do have another etch process -- dry etch -- that uses plasma instead, but it causes surface damage, and you don't want that under the gate. Also, dry etch chambers are a lot more work to maintain than a fume hood where you do wet etch. Furthermore, dry etch has its own set of hazards, and you have to deal with a lot more potentially toxic vapor.
Thinking a little more outside the box, you might look into using germanium instead of silicon. I don't know much about the germanium system, except that it supposedly grows less oxide. You're still going to have to deposit and remove oxide somehow, though, which means CVD reactors and silane. It's not going to be easy to get away from explosive toxic gases and dirty processes.
Not to mention DiBorane and Arsene... 1000C anneal cycles, teratogenic photoresist ethers, UHV equipment, and muti-kW RF sources. It's possible to demonstrate um scale MOS with a small lab, but not safely in anything resembling a normal garage. Hoping to replicate a multi-$B process at home is a fool's errand.
While we're at it, a modern scanner costs many million dollars, weighs tons, and sits on its own separate foundation on pilings that go down to bedrock so that it doesn't pick up vibrations from the air handling systems. DIY it ain't :)
A scanner is a photolithography tool like a stepper, except instead of exposing the entire shot at once, it sweeps (scans) a narrow rectangular exposure across the shot, and then steps to the next one. This allows for lighter, more precise optics. Confusingly, there's a piece of standard office equipment with the same name. Even more confusingly, Canon makes both kinds! Be sure you call the right technician for service.
I use "Armour Etch" to remove oxide from chips for reverse engineering, so it might work instead of HF for home chip fabrication. It contains bifluroride salts so it's somewhat safer (although I'm still very careful with it). You can buy it in craft stores for etching glass.
There's just...no reason at all to do it for business purposes. If you're a prepper or looking for a science project I can understand it, it's a cool project. But from a business perspective you can buy the same thing but better for dollars and have it the next day.
The lowest-cost options I know of for commercial custom chip fabrication are MOSIS and CMP. Their pricing starts at €650 for 0.35 μm, but it's true that the result is much better. However, turnaround time is measured in weeks. You seem to be suggesting that there are options that are one order of magnitude faster and two orders of magnitude cheaper (but perhaps with a much coarser feature size).
I was hoping that with 50 years of development behind us, the home fabricators could use less complex methods and less hazardous chemicals. In other words, can the folks who lived it help people like this by saying "If we had to do it over, I'd go about it like...."
Any suggestions? If you had to reboot the chip fab business on a budget what would be a more practical approach?