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> Now we know that it’s possible to make really good transistors with impure chemicals, no cleanroom, and homemade equipment. The good news here is that 2 of t
by actually_a_dog 5y ago
> Now we know that it’s possible to make really good transistors with impure chemicals, no cleanroom, and homemade equipment.
The good news here is that 2 of those 3 issues are pretty easily solvable. With some work, and a ton of HEPA air purifier machines, you could probably turn an area the size of a small shed or 1 car garage into a class 10000 cleanrom pretty easily. It would be simplest if this area were embedded in a larger area, like a 2 car garage, but, you could probably squeeze it into just a plain old 1 car garage.
Chemicals, you can buy online from scientific supply houses. Some, like acetone, you can buy from less specialized sources in high purity. Water and alcohol, you can either buy at high purity pretty easily, or buy lower grade stuff and purify it.
Of course, at the point where you're going for higher purity stuff like this, you might want to switch from acetone as a solvent to DMSO. DMSO itself is safe to handle and doesn't evaporate like acetone will.
> Silane
Yeah, nasty stuff. Toxic as hell, ignites spontaneously when exposed to air. I used to work near a rather large storage tank that contained the stuff. Needless to say, I am glad there never was an accident. :-) Very wise to avoid this stuff.
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https://www.americancleanrooms.com/class-10000-clean-room/ https://www.americancleanrooms.com/class-10000-clean-room/
https://en.wikipedia.org/wiki/Dimethyl_sulfoxide https://en.wikipedia.org/wiki/Dimethyl_sulfoxide
https://en.wikipedia.org/wiki/Silane https://en.wikipedia.org/wiki/Silane
- s0rce 5y agoIs DMSO really a replacement for acetone in most applications?
- ta988 5y agoIn some applications. It is dangerous if it dissolves things because now they can get under your skin easily. The problem is that it is not easily removed (requires much more energy than acetone) and it oxidizes. It is also more viscous and freezes at pretty high temperature (around 20°C).
- adrian_b 5y agoHis achievements are great, but the only reason why he could this without a cleanroom and with less pure chemicals is that he succeeded to find on eBay a batch of silicon wafers with the MOS gate oxide already grown on them. Growing the MOS gate oxide without extreme cleanness has no chance of succeeding. The difficulty of this process has caused a delay of many decades between the time when the MOS transistor was first imagined (in 1928 by Julius Edgar Lilienfeld, then also in 1935 by Oskar Heil) and the time when working MOS transistors were made for the first time, around 1960.
- baybal2 5y agoWant to stress how extreme cleanliness have to be. Free halogen ions from the air are enough to mess it up. That's why early fabs had very unusual placement requirements: not close to chicken farms, agriculture, water, or sewage treatment plants. Intel famously got seasonal yield losses which they traced to agricultural activities, and seasonal chicken coup cleaning.
- pottertheotter 5y agoAre they able to clean the air well enough now that it’s not an issue?
- eurasiantiger 5y agoIt’s not really feasible to separate noble gases out of the atmosphere in a building HVAC system.
- kragen 5y agoA class 10000 clean bench might be more practical. A lot easier to keep your cleanroom clean when the humans are outside of it, just sticking gloved arms in from time to time. Be careful about purifying alcohol. Some backward countries have religiously-based legal prohibitions on this. My own backward country tightly controls acetone as a "precursor" to "stupefacients". Nice thing about silane is that you don't have to worry about accidentally breathing it. There's a cheap and simple process for manufacturing it on demand from magnesium silicide, so you don't have to store it either.
- amelius 5y ago> With some work, and a ton of HEPA air purifier machines, you could probably turn an area the size of a small shed or 1 car garage into a class 10000 cleanrom pretty easily. I wonder if it would be possible to automate the entire process with robotics and reduce the effective "clean" space even further. There was this post a while back about a company that used thin cassettes to keep the wafers clean when moving between process steps.