(here at Medium-Size-Fabless-Semi-Inc, I'm in the middle of revving a bunch of parts that are about 10 years old, not because we want to add new features to them but because the process node is so obsolete it's becoming difficult to fab. Yes, they're getting new features, but that's not the primary driver of business)
On the other hand, because parts are physical objects, you can charge money for them. Piracy is .. not nonexistant (ask FTDI) but not a major concern.
There are some interesting corners for rapid-rev electronics, but there's a decision tree:
- can I do this with a microcontroller?
- if not, how about an FPGA?
- ok, there really is no alternative to ASIC, is the market size enough to support that?With an appropriate debug core in the same wafer, designers who'd completed a tape-out could connect to their chip well enough to repeat their design-verification tests on this real hardware, remotely even (no need to physically handle the device 'til you're certain it's working.) Once satisfied, customers could promote their design to be bonded out for installation into their PCB.
"Sure thing boss, we'll add an extra USART core to this afternoon's tape out."
You can do that, but it’s going to turn out poorly.
Part of the delay is really just commercial. Fabs are optimized for utilization - throughput, not latency. A fab operator will prefer to queue up a load of work with as few gaps as possible, and your shuttle service run has to fit in one of the gaps. If you're NVIDIA and you've already booked the fab, there might not be so much delay. But not zero.
Nice little backgrounder: https://siliconmasters.co/blogs/our-blog/how-photomasks-for-...
If there was a realistic way even to go from bare wafers to non-trivial custom chips in a small-batch fashion, you can bet there would be a cottage industry around it. I would love to live in a world where I could manufacture custom silicon as easily as I can manufacture a custom PCB or custom mechanical part.
But as it stands, quick-turn, rapid-proto "micro" fabs are obscenely expensive, to the extent that if you aren't absolutely certain you need the performance gains from custom silicon, justified by years of R&D that confirms the inadequacy of a multi-chip solution, then the idea is killed before any layout engineer is contacted.
Microfabs are either operated by research institutes, or they're booked solid for years, and basically printing money.