[nwiswell]

It's very similar to creating clothes by hand at home.

Can you do it, given the right tools, training, and patience? Yes.

Will they be any good? No.

Will they be cost-competitive? No.

Getting chips made on a shuttle run for an old node is very affordable. There's really no need for it.

(According to one MPW supplier, 10mm2 of 340nm, up to 10 dies, costs 6400 euros, and it's unlikely 340nm is achievable in a garage anyway)

[ghghgfdfgh]

From a business perspective, I agree that it’s a fool’s errand. But imagine being able to design and tangibly build your own computer, at home. 6400 euros is pennies for a business, but exorbitant for an individual.

I believe the way Sam Zeloof circumvents the enormous amount of capital needed for a chip fab by relying on modern technology to create 1970’s technology. He simply mounts a cheap digital projector onto a cheap microscope - they didn’t have that advantage in the 70s, and thus it cost millions to start a chip fab. My point is that it could conceivably be doable for an individual to create old computing technology with the advantages of living in the modern world. I certainly don’t have the drive to do it, but I wish someone did.

[nwiswell]

You'd spend far more than 6400 euros to do it at home.

If you did it often and didn't count your own labor costs, then maybe the average cost would be less, but that's an incredibly specific situation.

> I believe the way Sam Zeloof circumvents the enormous amount of capital needed for a chip fab by relying on modern technology to create 1970’s technology

Yes, exactly.

Old lithographic technology is so crude that you can even use modern high resolution laserjets to print masks (10000 dpi is less than 3 microns).

Even so, 1970s-era CVD, PVD, and plasma etch is still quite complicated, and CMP is impossible (it hadn't even been invented yet). So the devices you can create are significantly integration-constrained.

[_Microft]

Do you have examples for models of laser printers can actually achieve a resolution of 10000dpi? It doesn't need to be office equipment. Any example would suffice as I so far thought that laser printouts were limited to a maximum resolution between 1200 and 2400dpi.

[nwiswell]

Not at home, but at professional printing houses absolutely.

This isn't hypothetical, I've done it -- in grad school we would send out (I believe) 30000 dpi print jobs on transparent polyester film, and then adhere those to glass blanks to create cheap masks for MEMS fabrication. We had an old Canon i-line lithographic aligner that accepted the glass blanks.

I think the print jobs cost us about $100 each.

Here's the first Google result for a vendor (I don't remember who we used). There's a price list on their page and it looks like they have capability up to 50,800 dpi.

https://www.fineline-imaging.com/plotting_services.shtml

[xw38011]

If you're willing to go 10um then it's even easier and one can use a DLP to go maskless.

https://hacker-fab.gitbook.io/hacker-fab-space/fab-toolkit/p...

[ghaff]

Maybe a little different. For narrow enough definitions of "clothing," homemade clothing can be good. And there are other artisanal homemade crafts (e.g. woodworking) that can be good. But I agree in general.

[abdullahkhalids]

Will it give a 100% guarantee that there are no backdoors in your device? Yes.

This yes can be priceless in some circumstances.

[xeonmc]

really the main dealbreaker is HF at home, the rest of chipmaking really isn't that complicated on the process level for a crude design.

[ghghgfdfgh]

Most rust cleaner that you buy at the store is HF solution. For example, the one that teen used was 1.5% HF.

[nwiswell]

I can't believe that worked.

Industrially (by which I mean how it was done circa 1970), silicon oxide and silicon nitride was etched using a buffered HF solution known as BOE (buffered oxide etchant). The buffer was typically ammonium fluoride; because of the presence of the buffer, the concentration of fluorine ions in solution stays constant even as some of the fluorine attacks the substrate to form e.g. hexafluorosilicic acid. Since the concentration of fluorine stays constant, so does the etch rate.

If you just pull some rust cleaner off the shelf at home depot, the etch rate will crash as the concentration of fluorine ions decreases. That's compounded by the fact that the HF concentration isn't very high in the first place.

As a result it would be very difficult to determine how long your wafer should remain in the etch bath. Underetching could easily cause "opens" in the circuits from unremoved insulator, and overetching and/or undercut can destroy the patterns you're trying to produce. Either way it can ruin the chip.

[ghghgfdfgh]

Yep, he used an ammonium fluoride buffer. > Instead of a standard HF etch, a buffered oxide etch of NH4F (Ammonium Fluoride) in HF can be used to control the etch rate and photoresist lifting. I use approximately 20-30g of 100% NH4F per 50mL of HF (stock whink rust remover)

Ammonium fluoride definitely isn’t as easily accessible as rust cleaner, but you could buy it for a somewhat cheap price on Amazon.

[xw38011]

It's the internet which means you're shown the one IC that worked but not the 20 that didn't... Just like a grad student paper! :)