How low does the start to finish delay go with priority? That would be some indication of the theoretical opportunity to improve the experience. It might not even be an improvement for everyone. Just doubling the capacity for high priority runs would likely make a lot of engineers happier.As for high priority lots, that is a thing, and all fabs have them (as far as I know). However they are very disruptive to the fabs output/hurts wafer cost for the normal lots. For this reason foundries often charge extra for expedited lots. As far as I know development fabs do not have any special setup for high priority lots, just a higher volume of them. Depending on how much new equipment there is for that process impacts how negatively they effect factory output. When it is mostly new tools, then the priority lots don’t have to share with product lots, and cause minimal disruptions. Priority lots for prototypes, items of unexpectedly high demand that a customer is paying extra to expedite, or a new process that is using a large amount of current equipment has a larger impact on output.
Does dual patterning cost much time? I would assume they could do this as fast as processing a FOUP, then swapping pattern mask, then processing that FOUP again before moving it to be fixed and developed, so the increased mask count in this case does not count as increased process layers or much increase in processing time.