Comment by yannyu

> Yes, but isn't a big driver of layer costs the cost of the machines to build those layers?

Let's say the time spent in lithography step is linear the way you're describing. Even with that, the deposition step beforehand is surface area independent and would be applied across the entire wafer, and takes just as long if not longer than the lithography.

Additionally, if you were going to build a fab ground up for some specific purpose, then you might optimize the fab for those specific devices as you lay out. But most of these companies are not doing that and are simply going through TSMC or a similar subcontractor. So you've got an additional question of how far TSMC will go to accommodate customers who only want to use half a wafer, and whether that's the kind of project they could profitably cater to.