[GhettoComputers]

The article doesn't correspond to reality.

>3) Now you have 98% concentrated silicon dioxide. Purify it to 99.9% pure silicon dioxide.

>4) Purify it further to 99.9999999% polysilicon metal.

>While cutting-edge nanometer scale features are not likely to be accessible for a hobbyist, micron-scale amateur chip fabrication does appear to be quite feasible. I have not tried this myself, but Sam Zeloof has, and you should definitely check out his YouTube channel. I think you could probably even build some basic chips with far less equipment than he has if you get the optics right. You could probably make it a hobby business selling cusom chips to other tech people!

>A Word Of Caution: In case it wasn't already clear, I don't advise that anyone actually attempt making integrated circuits in their apartment in the manner shown in this video. The 'photoresist' and 'developer solution' in this video is just a colored prop. The real chemicals are usually hazardous and you should only work with them with proper safety gear in a well ventilated area or in a fume hood.

Its outdated and in reality you would go to Shenzhen or use a custom fab to make custom designed chips with raw materials sourced from special exotic materials that only make sense for scaled operation.

I highlighted the steps 3 and 4 because its not how its done at all. High grade silicon is obtained in a pure state and doped for the chips rather than obtaining random types and refining them.

Its not even easy compared to homemade nuclear reactors, which need a lot of natural sources of uranium to enrich but can be done, the refinement is more related to older germanium chips.

[nereye]

Somewhat related, it does not seem too expensive (~$100 per chip, minimum *50) to get an ASIC done (purely from a fab perspective and ignoring the large elephant in the room of coming up with a design in the first place), e.g. see https://www.zerotoasiccourse.com/ (no affiliation).

As for the design, one way is to re-use existing IP and join it together, e.g. see https://efabless.com/ etc.

[wrycoder]

He’s explaining, as crudely as possible, what’s going on in the semiconductor industry as a whole. Even Shenzen and TSMC are only small parts of it.

High purity polysilicon is still produced by zone refining.

[GhettoComputers]

Yes it is refined and doped, my point is that he leaves out the sourcing of essential materials that you don't refine but must get that is already pure, it has to be purer than any random silicon its like saying just get any sand that people will assume comes from beaches for construction when its essential that they are not worn or have rounded edges, except this is so specialized that it must come from one mine in the world. The limit was well understood in Soviet Russia with their inability to source the raw materials of comparable purity to produce microchips, even if the design was the same, the USSR was not able to produce them without what is considered essential to chips of good quality. https://www.sciencedirect.com/science/article/abs/pii/S00652...

Even today China cannot match the quality of American chips and relies on US raw materials from Spruce Pine for manufacturing chips. It isn't optional, its like saying you can make a 1:1 steak with nothing but beef bones or chicken. https://ashvegas.com/bbc-report-spruce-pines-high-quality-qu...

>This ultra-pure mineral is essential for building most of the world’s silicon chips – without which you wouldn’t be reading this article.

[wrycoder]

The BBC article is referring to high purity quartz, not silicon. It is used to make a quartz crucible - a large cup - of that high purity quartz. It’s essential that the crucible not contaminate the polysilicon.

(A note in passing: the semi industry doesn’t use hyperpure silicon. They use a lesser grade and add epitaxial layers.)

The crucible can stand the high temperature of molten silicon. The purified polycrystalline silicon is melted in the crucible. Then a single crystal ‘seed’ is dipped in the molten silicon and slowly withdrawn, while rotating. That’s how you make a high purity single crystal silicon ingot.

Before it’s zone refined, the poly is synthesized by reducing high purity silane gas (SiH4), which was in turn produced from quartz sand.

It would be interesting to know if the industry is still using natural quartz crucibles - the latest wafer size is now 450 mm - nearly 18 inches. Maybe someone else here can comment whether the traditional pulling process will be used at 450 mm.

[GhettoComputers]

You are right I mixed up silica and silicon my mistake. I found the wired article thats now paywalled and I mixed those two up. https://web.archive.org/web/20180808115837/https://www.wired...

>It would be interesting to know if the industry is still using natural quartz crucibles - the latest wafer size is now 450 mm - nearly 18 inches. Maybe someone else here can comment whether the traditional pulling process will be used at 450 mm.

Is that why they're round even though chips are square? Are the round parts thrown away or do they use them somehow? Reminds me of chicago style thin crust. https://en.wikipedia.org/wiki/Chicago-style_pizza#Thin-crust...

[wrycoder]

I had not heard of Spruce Pine - thanks for the references! In the very interesting Wired article you linked, I notice that the quartz goes to GE, which spins it into crucibles. So, I guess the size is unlimited.

The current silicon ingots are amazing - cylinders a foot and a half in diameter and maybe six feet long. They are handled with cranes.

The ingots are so large and the chips so small that there isn’t much waste. The edges are often used for test patterns.

The chips don’t have to be rectangular, but it’s easier, because they are separated with diamond saws or wire saws, which cut straight lines.

Some companies make photosensors in weird shapes using ultrasonic cutters.

[agumonkey]

Even the traditional disco cutters are probably worth their own book