Thread

1. HPsquared · 1790346004 · focus · HN ↗

   Semiconductor fabs involve a lot of hazardous chemicals, process changes and high energy consumption. Exactly the kind of thing European regulations tend to deter or slow down. Which is somewhat fine if there is nowhere else to build it, but if other places are easier, well...

   1. tgsovlerkhgsel · 1790459697 · focus · HN ↗

      What is so energy consuming around fabs? The light source? I always thought of these as high-precision, not-too-high-volume processes and would have expected energy requirements to be lower than e.g. a car factory (or similar to e.g. a mall) and completely negligible on a national grid scale or compared to something like a smelter or lignite mine.

      Edit: AI claims HVAC and air filtering/handling can be 40-50% of energy usage. Plus a megawatt per EUV scanner (ok, the latter matches what I would have guessed, but compared to the 16 MW of a single large bucket wheel excavator or estimates I've seen for large shopping malls, that's not that insane either).

      1. eric-hu · 1790485565 · focus · HN ↗

         Large shopping malls would fail the air purity requirements for semiconductor manufacturing.

         EUV lithography and etching rooms require ISO class 1 clean rooms. Those can have a maximum of 10 particles of size 0.1 microns per cubic meter.

         While a shopping mall can get away with 2 - 4 air changes per hour, an ISO class 1 clean room requires 400-600 an hour, or about 10 a minute. Airflow needs to also be controlled: vertical and laminar. Every human entering the cleanroom needs to undergo an air shower with speeds of 60-90 mph to shear off loose skin flakes, hair and lint. This area needs to maintain constant positive air pressure to repel outside dust as humans move in and out.

         In the EUV lithography systems, temperature control is measured in milliKelvins (0.001 C). If a wafer stage has a temperature variation of 0.05 C, the silicon expands by a few nanometers and the multimillion dollar batch is toast. Meanwhile in the same room, the EUV machine is generating extreme ultraviolet light using a plasma light source that gets to above 200,000 C. That's 40x hotter than the surface of the sun.

         > I always thought of these as high-precision, not-too-high-volume processes

         EUV rooms are churning out about 150 wafers an hour, 24/7. That sounds like not too high of a volume, but each wafer is about 500 cpus. So 75,000 cpus an hour.

         1. fnord77 · 1790499978 · focus · HN ↗

            seems like doing this in a vacuum would be more economical

            1. falserum · 1790505091 · focus · HN ↗

               Laymens guess what problems it could introduce:

               Vacuum does not dissipate heat well (extra engineering in that department)

               Vacuum is never 100% vacuum. If you have some dust in the air, it will mostly flow to the direction of the airflow, but in vacuum dust particles will do random walk thing and settle on surfaces.

               1. tatjam · 1790510022 · focus · HN ↗

                  Plus the fact that then you need the everything to be structurally strong to be able to support 1atm of pressure differential, keep the vacuum sealed, and keep material degassing under control, so you end up with some heavy duty, expensive stuff. Pretty sure a lot of steps in the chip fab are done under very very high vaccums tho!

                  1. tremon · 1790515528 · focus · HN ↗

                     In general it's easier to control the air you're blowing into a room than what you're extracting, so I'd expect it would be more economical to keep the fabrication rooms under high pressure than low pressure. Also, in case of a leak, air and contaminants will flow out of the room instead of into it.

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