Mask size or fabrication geometry size? I'm guessing you mean the latter. It depends on the generation of these chips (moving to a smaller process) but I know the 6502 used a 10 um process at introduction, and I think the 8080 used a 5 or 6 um process. Don't know about the Z80.

For comparison, the 80386 was fabricated with a 1um process.

Wikipedia says that the 6502 was originally fabbed on a 8 um process with a die size of 16.6mm^2.

I don't know, the Z80 data sheet I briefly skimmed doesn't even seem to mention that detail. However if this technology can offer what was available in the 70s, and on their site they say it can be used for analog ICs too, it woud seem logic to use it to remake older obsolete chips (how many 6522 and SIDs were fried?), along with some newer versions of older analog chips.