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. cwbriscoe · 1790491688 · focus · HN ↗

            I doubt I could even work in a fab having psoriasis.

            1. bob1029 · 1790524666 · focus · HN ↗

               It is mandatory to wear a bunny suit, mask and goggles in every fab I've been inside of.

               They have special security guards who make sure you do the procedure correctly.

         2. 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.
            2. magimas · 1790520354 · focus · HN ↗

               I worked a lot with and built up ultra-high vacuum systems during my PhD. At least for that level of vacuum, you introduce a lot of headache.

               You can't use normal plastic or any kind of lubricant anymore because it starts degasing inside the vacuum, pump down after opening to air is a multi-day process that involves heating everything up to 150°C to get rid of the water that will settle on basically every surface when you pull the vacuum, every electricity feedthrough is a potential point of failure, transfering objects between different stages is a huge hassle etc. pp.

               I'm sure there's still lots of UHV and HV systems in a chip fab, but there's no way that's easier on a full factory scale than clean room operation.

               1. pfdietz · 1790522696 · focus · HN ↗

                  I don't think he meant UHV, just vacuum good enough that dust particles are not suspended.

                  Heat dissipation would be the obvious problem.

         3. pletnes · 1790502854 · focus · HN ↗

            Exactly this. The process is super complex and expensive. The result, a cpu, is sold for a few dollars. To be profitable, the scale / volume has to be absolutely massive!
         4. [deleted] · 1790526491 · focus · HN ↗

            [deleted]

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