Relative to economic output, not really. In absolute terms, yes, because the plants are massive and "facilities staff" misses a lot when you're talking about machines worth 150 million a piece, clean rooms, and billions in depreciation per year.

They keep the process parameters within the optimal zone. That is considerably more complicated than it sounds. They also work on incremental improvements.

From what I understand, a chip plant's workers have PhDs because when problems arise on the line, they require a lot of knowledge to fix.

The R&D fab(s) definitely have a high number of PhDs. I don't know about the production fabs. PhDs will definitely visit when starting up a new fab or process or when issues need to be addressed.

If it is anything like BioTech, they will. I was shocked when I joined a large firm and realized that the person spending most of their day breaking down boxes and checking log books has a masters from Berkeley. Most of the techs running equipment have masters/Phds.

As I have come to realize, when a mistake or delay costs $XX million, it often makes sense to hire with high educational background. I have also come to realize that your bog standard MS or Phd isn't as talented as you might think.