> Depending on who you ask, it seems the cheapest cost per transistor is somewhere in the 20-40nm ballpark.
While correct, this is only true because of all the old infrastructure sitting out there that has been fully depreciated but still works fine. It used to be the latest and greatest thing and paid for itself back then. Nowadays it is just sitting on the asset sheet of a bunch of companies who are all going "if it still makes money, keep running it!".
The paradox of this all is what you identified: "if so, it would imply there would be a long-time demand for these process nodes". No one is going to invest in developing old nodes because the ROI isn't there. The demand is, but there probably isn't much cost differential between building a nearly leading edge fab and a 60nm fab.
If you could sell a turnkey 60nm fab right now that was delivered and setup quickly the demand would be insane. But no one can because fabs have never really been turnkey. When you factor in the cost to develop all of this, the capital you'd have tied up, etc. the ROI suddenly fails to compete with interest bearing bonds I'd guess.
While correct, this is only true because of all the old infrastructure sitting out there that has been fully depreciated but still works fine. It used to be the latest and greatest thing and paid for itself back then. Nowadays it is just sitting on the asset sheet of a bunch of companies who are all going "if it still makes money, keep running it!".
The paradox of this all is what you identified: "if so, it would imply there would be a long-time demand for these process nodes". No one is going to invest in developing old nodes because the ROI isn't there. The demand is, but there probably isn't much cost differential between building a nearly leading edge fab and a 60nm fab.
If you could sell a turnkey 60nm fab right now that was delivered and setup quickly the demand would be insane. But no one can because fabs have never really been turnkey. When you factor in the cost to develop all of this, the capital you'd have tied up, etc. the ROI suddenly fails to compete with interest bearing bonds I'd guess.