In scientific terms - some chemical (used in the production) was supposed to be 99.999999% pure...but was not, and the offending impurity(ies) was (in terms of consequences for the uber-delicate production processes) Profoundly Unhelpful.

In poetic terms - a hundred thousand tiny demons got loose in the plant, and each and every one of them will need to be laboriously exorcised, before production can resume.

Exactly. Pretty poor news article not addressing this. At least they could have added "The manufacturer declined to comment on how the contamination occured" if that's the case.

Poor manufacturing process? (Of course poor is relative in today's silicon) Sabotage? Earthquake? (They have them all the time) Radiation from Fukushima? (Maybe a bit late 10 years after)

FOD: https://en.wikipedia.org/wiki/Foreign_object_damage

Working in Communications/Medical/Aerospace manufacturing, this is a MASSIVE concern.

Impurities in raw materials?

maybe dust?