[supernova87a]

>I believe it is something like a 3 millions dollars lost per minute if they are idle.

I think that's overestimating, although you are right it is damn expensive.

Order of magnitude I would say it's more like: Fab has lifetime of 2-3(?) years, and costs $10B to build and amortize. So every minute of idled factory capital = $6,000 in pure cost of the facility.

(although, if you think of it in potential lost revenue terms, then you may be more correct.)

(Actually we can also do that arithmetic, according to https://www.forbes.com/sites/willyshih/2020/05/15/tsmcs-anno...

240,000 wafers per year * 500 chips per wafer * $100? = $12B per year revenue. Also is something like $22k per minute)

[chrisseaton]

> Fab has lifetime of 2-3(?) years

Many Intel fabs are from the early 2000s. Some are from the 90s. What do you mean 2-3 years?

https://en.m.wikipedia.org/wiki/List_of_Intel_manufacturing_...

[monocasa]

I think they're referring to each line as a new fab, rather than the complex of buildings they're in, which is pretty fair.

[ardy42]

>>> Fab has lifetime of 2-3(?) years

>> Many Intel fabs are from the early 2000s. Some are from the 90s. What do you mean 2-3 years?

> I think they're referring to each line as a new fab, rather than the complex of buildings they're in, which is pretty fair.

Even so, wouldn't the 2-3 year number only apply to CPUs? Couldn't they keep the lines running making things that don't require top of the line processes, like USB controllers, etc.

[monocasa]

Yes, for chips that need leading edge density like CPUs.

Of course the lines stay open after that for cases you've laid out, but there's a lot of financial reasons why that needs to be basically gravy train money at that point with the lines being fully amortized and having paid for themselves many times over.

[supernova87a]

For those retired lines, don't they sell them off to lower tier manufacturers pretty quickly? Say, within 5 years?

I am no expert but I didn't think the site would be just accumulating its n-1, n-2 generation lines to produce lower grade stuff in the same fab walls. They take up space that they want to continue producing top of line latest output. I thought.

[monocasa]

They're not really taking up space per se. For the cost of a fab, a new building (or new wing of a building) is peanuts.

Adding on to that, in a lot of ways the fab is the building, and at a bare minimum you'd be resetting a lot of the yield issues you fixed by moving it to a new space. So then you'd be left with an old node and yield issues, and what's the point of that?

There's also a ton of trade secret style IP still in the old nodes that could help a competitor, so why let it leave your property? Intel for instance is so into preventing trade market theft on the specifics of their nodes that they (at least used to) manually drill out every mobile device camera allowed in their fabs, in addition to the normal "no outside electronics past this point" security stations.

[supernova87a]

That's correct. A reasonable way to think of it is to calculate the cost of the thing that you're replacing every couple years, and the output it produces in that time. So the CPU producing line at <x>nm process, or whatever unit you choose. The building or site itself ("the fab") isn't the important thing.

[systemvoltage]

3 million dollars might be the cost of one FOSB (carries some 18-24 wafers) if you dropped it :)