It sounds like the demand sharply increased recently due to smartphones and other advancements while production stayed steady.
I imagined fabs like 3d printers. I thought the toughest part is the design, and once you have it, there's now plenty of places where you can print it.
Intel planned (don't know if they ended up doing it) to convert a plant built in 2010 to memory fabrication and it was going to cost 3.5 billion dollars and take years.
It's not plug and play.
Well, you'd need the machines for that – there’s only a handful of companies able to build the EUV lithographic machines for that, most of them small German companies with a few dozen to hundred employees.
And they can’t just increase production.
In memory, smaller means less space to store your bits. I remember a quote from somewhere that with TLC at 20nm, you could lose only 1 ELECTRON PER YEAR from the floating gate to meet the memory retention spec.
Also, NAND had smaller feature sizes than logic for some time, before they really hit the wall. They innovated a lot of advanced techniques like quad patterning for memory cells. It helps in memory that you are optimizing for one and only one cell.
But the silicon factories cost billions each, so no-one is going to scale up because of a temporary shortage. The same, even more so, for the factory-factories.