Comment by icegreentea2
5 years ago
The non-opex costs can also be very significant. This is from a few years ago (https://www.extremetech.com/computing/272096-3nm-process-nod...), but you can significant differences in start-up costs per node.
In addition, it's just going to be harder to get fab time on more cutting edge nodes. Your going to be competing for fab time against bigger competitors with more at stake, and that's going to cost you as well.
Finally, it's only true that the long-run opex per working transistor is lower on smaller processes. Many processes are actually more expensive on a "per working chip" basis at introduction than their predecessors. It's only as process is worked on and improved that the per chip cost (ignoring opex) actually beats the preceding node.
Usually a fab will start shipping product on a process once it's "good enough" - the yields and costs (and therefore profit per unit) is sufficient to make sense (even if it's not necessarily cheaper than the old process).
>Finally, it's only true that the long-run opex per working transistor is lower on smaller processes. Many processes are actually more expensive on a "per working chip" basis at introduction than their predecessors.
Yes, but if there is a design that uses a fixed amount of transistors, then the chip size will be smaller on smaller nodes. So even if there are more defects per transistor on a new/small node, it is possible that the yield per cost (even with more expensive wafers) might be higher.
That's a possibility, and that's what the manufacturers are driving for, but it's not guaranteed. All the way back in 2015, we were already seeing projections that cost per transistor would flatline or even increase as process nodes continue to shrink (http://www.monolithic3d.com/blog/intel-the-litmus-test for example).
I have no idea where exactly the state of the art stands (certainly Intel was/is having trouble getting their 10nm to squeeze out any type of economically viable product).