6 ms·

Any idea why the colour on the fab floor is an odd yellow hue? Is the standard colour spectrum for interior lighting not compatible with chipmaking? I'm imagini

by geenew 5y ago

Any idea why the colour on the fab floor is an odd yellow hue? Is the standard colour spectrum for interior lighting not compatible with chipmaking? I'm imagining a situation akin to the darkroom requirements for processing photographs.

sibrahim 5y ago
My understanding is that was the original purpose, but probably unnecessary given that all the relevant process steps are encased in tools that are not exposed to the general clean room environment in operation (they have to maintain a higher grade of clean room internally). However, I suspect it's probably going to continue being propagated forward due to Copy Exactly which has historically meant that Intel documents and copies the smallest details in all their fabs just in case they are necessary. In the end, if it ain't broke...
- mrlonglong 5y ago
  In short, they've cargo culted themselves. No wonder they've lost their place as makers of powerful processors.
  - boondaburrah 5y ago
    Why would you not want the additional protection if you have to pick a colour to make the room anyways?
    - mrlonglong 5y ago
      Copying everything implies they do not have full understanding of what makes for a successful process.
      - speed_spread 5y ago
        It's possible that some level of unresolved empirical "magic" be involved in the process, which does not diminish the value of the end product. Why deprive yourself of hard learned lessons even if you don't understand it all?
  - toss1 5y ago
    Chesterton's Fence [0] should overrule fear of cargo culting, especially when the fence (or in this case color) was clearly put up by people who really knew what they were doing at the time. Unless there is a significant cost to it, and unless the benefit is understood, there is no reason that they should be faulted as ignorant cargo cultists simply for keeping it in place. [0] https://www.chesterton.org/taking-a-fence-down/ https://www.chesterton.org/taking-a-fence-down/
    - sibrahim 5y ago
      Right. There's not a compelling reason to switch and there's more than a hint of CYA mixed in with Chesterton's Fence: https://www.bloomberg.com/news/articles/2016-06-09/how-intel-makes-a-chip https://www.bloomberg.com/news/articles/2016-06-09/how-intel... > For decades, Intel’s cleanrooms have been lit like darkrooms, bathed in a deep, low yellow. “That’s an anachronism,” says Mark Bohr, a small, serious man who has spent his entire 38-year career making chips, and who’s now Intel’s top manufacturing scientist. “Nobody’s had the courage to change it.”
kevin_thibedeau 5y ago
Photoresist is UV sensitive.
boondaburrah 5y ago
Anything UV sensitive is usually done in a yellow room, so that's probably it. I know this is exactly the case for PCB manufacture and printing press plate making to lessen accidental exposure, so it's exactly like a red safelight in a darkroom.
simne 5y ago
This remembers me, when many years ago I worked with old chemical photography - used special light to limit parasitic exposure of film and photopaper. Usually used dark red light, or yellow-green. And I lived in absolutely typical apartment, and used for photography ordinary bathroom, but switched off normal lights and used special lights, and apartments become looking like them from fantastic films. So, yes, my first education electronics and I've few times been at real fabs. At fabs there are two things which don't appear in typical homes - many devices emit ultraviolet and it is extremely powerful, so appear even through covers, or use open electric heaters, which emit red. Main lights I have seen there, where just ordinary fluorescent lamps, but I sure, on more modern fabs, used special lamps or color filters, to filter out part of spectrum which could cause unnecessary additional dose for photo-chemistry.
- kurthr 5y ago
  Not all lithography is Deep/Xtreme UV even in the newest fabs, because the equipment is so expensive and relatively slow. A lot of lithography is done the old way and is sensitive to UV from any lights. Box to box processing is almost complete, but there are times when a box may need to be opened or exposed to ambient light. So there are some pretty good reasons to not to increase uncontrolled UV light exposure.
simne 5y ago
And photoresist is not only UV sensitive, people have success on exposure it with just very powerful halogen lamps, which don't have much UV. So at fabs, usually, main light is not powerful, or have some color filters.
xyzzy21 5y ago
It's because photoresist is sensitive to deep blue out to UV so you want to avoid that kind of light as wafers with photoresist applied but not-yet-exposed are running around in their robotic FOUPs through the facility. It's exactly analogous to red safe lights used for film print photography.

by geenew 5y ago

sibrahim 5y ago

My understanding is that was the original purpose, but probably unnecessary given that all the relevant process steps are encased in tools that are not exposed to the general clean room environment in operation (they have to maintain a higher grade of clean room internally). However, I suspect it's probably going to continue being propagated forward due to Copy Exactly which has historically meant that Intel documents and copies the smallest details in all their fabs just in case they are necessary. In the end, if it ain't broke...

mrlonglong 5y ago
In short, they've cargo culted themselves. No wonder they've lost their place as makers of powerful processors.
- boondaburrah 5y ago
  Why would you not want the additional protection if you have to pick a colour to make the room anyways?
  - mrlonglong 5y ago
    Copying everything implies they do not have full understanding of what makes for a successful process.
    - speed_spread 5y ago
      It's possible that some level of unresolved empirical "magic" be involved in the process, which does not diminish the value of the end product. Why deprive yourself of hard learned lessons even if you don't understand it all?
- toss1 5y ago
  Chesterton's Fence [0] should overrule fear of cargo culting, especially when the fence (or in this case color) was clearly put up by people who really knew what they were doing at the time. Unless there is a significant cost to it, and unless the benefit is understood, there is no reason that they should be faulted as ignorant cargo cultists simply for keeping it in place. [0] https://www.chesterton.org/taking-a-fence-down/ https://www.chesterton.org/taking-a-fence-down/
  - sibrahim 5y ago
    Right. There's not a compelling reason to switch and there's more than a hint of CYA mixed in with Chesterton's Fence: https://www.bloomberg.com/news/articles/2016-06-09/how-intel-makes-a-chip https://www.bloomberg.com/news/articles/2016-06-09/how-intel... > For decades, Intel’s cleanrooms have been lit like darkrooms, bathed in a deep, low yellow. “That’s an anachronism,” says Mark Bohr, a small, serious man who has spent his entire 38-year career making chips, and who’s now Intel’s top manufacturing scientist. “Nobody’s had the courage to change it.”

kevin_thibedeau 5y ago

Photoresist is UV sensitive.

boondaburrah 5y ago

Anything UV sensitive is usually done in a yellow room, so that's probably it. I know this is exactly the case for PCB manufacture and printing press plate making to lessen accidental exposure, so it's exactly like a red safelight in a darkroom.

simne 5y ago

This remembers me, when many years ago I worked with old chemical photography - used special light to limit parasitic exposure of film and photopaper. Usually used dark red light, or yellow-green. And I lived in absolutely typical apartment, and used for photography ordinary bathroom, but switched off normal lights and used special lights, and apartments become looking like them from fantastic films. So, yes, my first education electronics and I've few times been at real fabs. At fabs there are two things which don't appear in typical homes - many devices emit ultraviolet and it is extremely powerful, so appear even through covers, or use open electric heaters, which emit red. Main lights I have seen there, where just ordinary fluorescent lamps, but I sure, on more modern fabs, used special lamps or color filters, to filter out part of spectrum which could cause unnecessary additional dose for photo-chemistry.

kurthr 5y ago
Not all lithography is Deep/Xtreme UV even in the newest fabs, because the equipment is so expensive and relatively slow. A lot of lithography is done the old way and is sensitive to UV from any lights. Box to box processing is almost complete, but there are times when a box may need to be opened or exposed to ambient light. So there are some pretty good reasons to not to increase uncontrolled UV light exposure.

simne 5y ago

And photoresist is not only UV sensitive, people have success on exposure it with just very powerful halogen lamps, which don't have much UV. So at fabs, usually, main light is not powerful, or have some color filters.

xyzzy21 5y ago

It's because photoresist is sensitive to deep blue out to UV so you want to avoid that kind of light as wafers with photoresist applied but not-yet-exposed are running around in their robotic FOUPs through the facility. It's exactly analogous to red safe lights used for film print photography.