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NAND flash fab shell designs

N

nghanayem

Well-known member
At least in the case of Kioxia it would seem their fabs are a good bit taller than modern logic fabs. Fabs 2-5 look to be a similar height to TSMC's Fab 18 and Intel's D1X. Given these logic fabs are taller than prior generations of fab shells in order to accommodate the large size of EUV tools, and that NAND will never have any need for EUV tooling; why would Kioxia go through all of the extra expense to build their fabs so tall? Furthermore do other NAND manufactures build out their NAND fabs this tall, or is this just a Kioxia-ism?

NAND fab:
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Modern Logic fabs:
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Cleanroom space in a fab is expensive space, while support areas are cheap, so taller, to me, equates with more support space, rather than more cleanroom.

It could mean a second cleanroom level, stacked, but I tend to discount this possibility.

More support space per unit of cleanroom space is an ongoing trend. You could readily imagine that each tool in the latest Kioxia fab will have more gases/chemicals or more chambers, or both, in each tool, which in turn is multiplicative in the support below, which is what drives the taller profile, as cleanroom space remains relatively constant but chemicals proliferate like mad.
 
www.anandtech.com

A Visit to Intel’s D1X Fab: Next Generation EUV Process Nodes

www.anandtech.com www.anandtech.com

"One thing you will notice when you go into a fab is also how tall it is. These buildings are designed to be autonomous but also easy to maximize uptime. That means if something fails (like a ceiling light), it can be repaired without disabling anything. Even the ceiling lights have access from above the fab if they ever need to be repaired or replaced. But the reason why the fab area is so tall is because some of the machines are two stories high, especially the EUV machines. Sometimes these have to be lifted in, or use reinforcement beams to install them. It’s quite hard to miss."
 
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Having a subfab/utility level and air circulation above the clean room is hardly unique to NAND though. It would also strike me as odd that Kioxia would have way more chems and gas lines then a logic fab. Given they use many of the same tools (admittedly in different ratios from DRAM and logic) you would think that those requirements are similar. If anything given the more complex structures being formed you would expect modern logic fabs to have even more difficult subfab/utility routing.

Agreed on the two clean room levels sounding unrealistic though.

And good catch on the Samsung nand fab. Interestingly enough their leading edge logic and DRAM fabs also have a similar taller than TSMC/Intel look to them (at least the S3 and the logic part of the S5 lines do).
 
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An idea just occurred to me
Samsung:

Intel:

TSMC:

It seems like intel and TSMC fabs have large utilities buildings next to their fabs. Meanwhile in the pictures of the Samsung and Kioxia fabs there seem to be fewer (and sometimes no) utility buildings visible. It also seems like there is more exhaust chimneys for the Samsung fabs than the TSMC or intel fabs. This might indicate that rather than having just a subfab and a utility level, maybe Samsung and Kioxia design their fabs with multiple utility levels to avoid having to "waste space" on separate utility buildings. If I had to hazard a guess on an arrangement I would have the intergraded utility building stuff on the first floor, then either the subfab or traditional utility level, clean room, fan deck, and at the very top either the subfab or traditional utility level (whichever is lighter). Although maybe I am overestimating how heavy tools can be, and maybe it is fine if the cleanroom is on the 4th floor rather than the 3rd. Given the fact they need to eventually get exhaust out the top, maybe the integrated utility building might actually be the top floor (assuming the building can be made tough enough to support that weight that high up).
 
Some of it is building code related, in the US it is hard to design a single level cleanroom that meets the building codes, in Korea Samsung builds multi story buildings with 2 of the levels used as cleanrooms. At least some of their fab buildings are 8 stories tall, that isn't allowed in the United States.
 
Scotten Jones said:
Some of it is building code related, in the US it is hard to design a single level cleanroom that meets the building codes, in Korea Samsung builds multi story buildings with 2 of the levels used as cleanrooms. At least some of their fab buildings are 8 stories tall, that isn't allowed in the United States.
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2 clean room floors! Is this speculation or known information? If this was the case, those monster Samsung fabs are even bigger than I thought (and I already thought they were massive).
 
nghanayem said:
2 clean room floors! Is this speculation or known information? If this was the case, those monster Samsung fabs are even bigger than I thought (and I already thought they were massive).
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It could be one double height floor instead of two separate floors.
 
This is some serious speculation. Many companies have "tall fabs" There are absolutely companies with two levels of clean room space in one building. In general they are have separate functional areas (ie there are not two fabs, there is a two level fab with certain activities on each level). Fab designs tend to be copied within a company, and quite different from company to company based on how they choose to optimize land, building, chemical routing, etc. I have also seen fabs with "unused interstitials" for "future use".
 
Is that due to the site condition Kioxia decided to go taller instead of building deep basement to host various kinds of equipment and infrastructure? TSMC fabs, like the Arizona fabs, typically have very deep basements.
 
nghanayem said:
2 clean room floors! Is this speculation or known information? If this was the case, those monster Samsung fabs are even bigger than I thought (and I already thought they were massive).
Click to expand...
I know it for a fact, if I am posting a rumor or speculation I say so. A lot of these fab have a floor running NAND and a floor running DRAM, some fabs have a mix of DRAM, NAND and Logic between the two floors.
 
MKWVentures said:
This is some serious speculation. Many companies have "tall fabs" There are absolutely companies with two levels of clean room space in one building. In general they are have separate functional areas (ie there are not two fabs, there is a two level fab with certain activities on each level). Fab designs tend to be copied within a company, and quite different from company to company based on how they choose to optimize land, building, chemical routing, etc. I have also seen fabs with "unused interstitials" for "future use".
Click to expand...
It not speculation on my part. Samsung has cleanrooms on two floors in many if not most of their "fabs", there is often a NAND Cleanroom and a DRAM cleanroom. In Pyeongtaek there is P1 with two floors of cleanrooms with NAND and DRAM, P2 has 2 floors of cleanrooms with NAND, DRAM and Logic, P3 has 2 floors of cleanroom with NAND, DRAM and Logic and all three phases are connected to V2 that has two floors of EUV tools that service both the logic and DRAM fabs.
 
Scotten Jones said:
It not speculation on my part. Samsung has cleanrooms on two floors in many if not most of their "fabs", there is often a NAND Cleanroom and a DRAM cleanroom. In Pyeongtaek there is P1 with two floors of cleanrooms with NAND and DRAM, P2 has 2 floors of cleanrooms with NAND, DRAM and Logic, P3 has 2 floors of cleanroom with NAND, DRAM and Logic and all three phases are connected to V2 that has two floors of EUV tools that service both the logic and DRAM fabs.
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As I mentioned 2 floors of cleanroom is possible.... I have seen it. I was referring to other people speculation. Good Input on details and building codes
 
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