TSMC adding another $28B to the initial $12B investment to build a second fab, targeted for 3nm. The original fab is being shifted to 4nm, from 5nm.
“At scale, these two [factories] could meet the entire U.S. demand for U.S. chips when they’re completed. That’s the definition of supply chain resilience. We won’t have to rely on anyone else to make the chips we need.” - obviously false, but makes good press.
I have former students working at Intel in AZ. As the droughts continue, I have no idea how a state that is losing farms from lack of water can manage to provide enough for clean water guzzling fabs. I can see the tax breaks as a lure, but still. Do today’s fabs no longer require large volumes of water?
The key word here is clean. Dirty water can be cleaned. All it takes is energy. You have some loss to evaporation. But most can be recovered and recycled in most process operations. It costs some but if water is truly short and AZ is the right place for operation its not a big deal. Not a technology hassle. The technology required is readily available.
The Fabs use a minuscule amount of water compared to farming. One standard fab uses as much water as three to five center pivot irrigation fields. When you fly over, you can see thousands of these fields. If the new Fabs are being built on existing farmland, there is likely a net savings of water.
That said, the water problem is going to blow up the west in the next 20 years.
Yep. I started a long reply about history that none of you would care about. Basically, fabs and other facilities that used process water went from little regulation in the sixties and seventies to having to make their discharge process water drinkable or better. And as sewage treatment plants sprang up all over, their staff would seek and destroy any facility that was dumping chemicals into the sewage that interfered with their processing. (Well, not destroy, but a cease and desist order shutting the plant down was the functional equivalent.)
When hafnium gates started showing up, fabs needed to get serious about water recycling. Nitrates of rare earths are difficult to remove. Since fabs didn’t need to use nitrates, the problem was usually some farmer spreading ammonium nitrate on his fields. The more water you recycled, the less nitrates you had to deal with.
The nitrates presumably enter with the feed water coming into the system. That quantity should be small–replacing only evaporation or other losses. Pretreatment of that water by ion exchange to make deionized water is common in the chemical industry. Why let the nitrates in in the first place?
Maybe I wasn’t clear. The fabs will do what it takes to only let pure water in. The national, state, and local authorities will ensure that any water leaving the fab will be at least drinkable. The least expensive way to do both is to minimize the amount of incoming water that they have to purify and to use equipment that is designed to do the recycling local to the equipment.
Hmm, maybe an example will help. A CMP (chemical mechanical polishing–or planarization) processing node doesn’t need to get the water it recycles into the slurry very clean, but it does need the water used in cleaning the wafer after the polishing is done squeaky clean. The major concern is about particles, especially those too small to see, in the final rinse. Single digits per wafer of particles that cause defects used to be good. Way less than one per wafer is the target today. Parts per million of various salts may not be a problem–depends on the solubility of the particular salt. Other process nodes have different criteria. For example, you do not want any active polymer particles in the water used in mixing/thinning the photoresist. I won’t go into the chemistry used, but one active polymer site can cause the whole batch of resist to go bad. The processing uses chemicals that multiply the effect of one (DUV or EUV) photon to cause the effect of that photon to spread out (in three dimensions) into a polymer molecule a couple of nanometers in diameter. Give it an extra hour or so, and the particle will be microns in diameter.
The example of a farmer fertilizing a field was just to indicate that you really needed to guard and monitor the water coming in, and recycling within the fab reduces the cost of doing that.
