jms_embedded
Active member
So TSMC is constructing its first Arizona fab with a planned output of 20K wafers per month using its 5nm process. There's room at this site for 5 more fabs in the future. The $12 billion number in TSMC's announcement is total spending on this project (the AZ site) from 2021 to 2029, presumably including more fabs. Scotten Jones posted an initial estimate for this 20K wpm fab of $5.4 billion.
Thought experiment: (very hypothetical)
It's December 2022 and the chip shortage is still painful. TSMC is doing so well that they decide they will construct a second fab with another 20K wpm at this site.
Choice 1: another 5nm fab, presumably about the same price.
Choice 2: a 40nm fab because there is a huge shortage of 40nm wafer capacity (again this is very hypothetical)
Questions, looking for very rough estimates:
- For choice 2, how much would it cost them to build it as a percentage of 5nm fab cost? I am assuming it would be less expensive because it's not EUV and 40nm is a much older node. (10% as much? 80% as much?)
- For choice 2, with today's prices what's the rough difference in cost per wafer they charge for 5nm vs. 40nm at high volumes (say at least 5% of total fab output)? is it more like 5:1 or 2:1 or 1.2:1 ?
- How "competitive" is choice 2 if "competitive" is defined as the ratio of this new fab's costs to other TSMC fabs with the same process?
I'm guessing choice 1 is fairly competitive, maybe 1.1 - 1.3x as high as other TSMC 5nm fabs given lower wpm and US location.
What about choice 2? 2x as high as other TSMC 40nm fabs? 10x?
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Intent of thought experiment: My intuition tells me it doesn't make sense to build a new 40nm fab for two reasons:
1. given the site costs, they can earn more profit at this site with 5nm than with 40nm (costs more to build but higher return)
2. 40nm will be less competitive than 5nm because existing 40nm fabs have already been depreciated so their operating cost is much lower than a new 40nm fab.
But I was wondering if it's just slightly less sensible or completely bonkers to build a new 40nm fab.
(For the purposes of this question, ignore expectations of the foolishness of adding new 40nm capacity and the foolishness of foundry customers asking for capacity at 40nm instead of smaller nodes; assume that the demand is there.)
Thought experiment: (very hypothetical)
It's December 2022 and the chip shortage is still painful. TSMC is doing so well that they decide they will construct a second fab with another 20K wpm at this site.
Choice 1: another 5nm fab, presumably about the same price.
Choice 2: a 40nm fab because there is a huge shortage of 40nm wafer capacity (again this is very hypothetical)
Questions, looking for very rough estimates:
- For choice 2, how much would it cost them to build it as a percentage of 5nm fab cost? I am assuming it would be less expensive because it's not EUV and 40nm is a much older node. (10% as much? 80% as much?)
- For choice 2, with today's prices what's the rough difference in cost per wafer they charge for 5nm vs. 40nm at high volumes (say at least 5% of total fab output)? is it more like 5:1 or 2:1 or 1.2:1 ?
- How "competitive" is choice 2 if "competitive" is defined as the ratio of this new fab's costs to other TSMC fabs with the same process?
I'm guessing choice 1 is fairly competitive, maybe 1.1 - 1.3x as high as other TSMC 5nm fabs given lower wpm and US location.
What about choice 2? 2x as high as other TSMC 40nm fabs? 10x?
----
Intent of thought experiment: My intuition tells me it doesn't make sense to build a new 40nm fab for two reasons:
1. given the site costs, they can earn more profit at this site with 5nm than with 40nm (costs more to build but higher return)
2. 40nm will be less competitive than 5nm because existing 40nm fabs have already been depreciated so their operating cost is much lower than a new 40nm fab.
But I was wondering if it's just slightly less sensible or completely bonkers to build a new 40nm fab.
(For the purposes of this question, ignore expectations of the foolishness of adding new 40nm capacity and the foolishness of foundry customers asking for capacity at 40nm instead of smaller nodes; assume that the demand is there.)