6" wafer it looks like.  Probably built in an academic fab.  It's strange that the wafers have flats on 2 sides, that isn't standard.  I have a list of all operating fabs somewhere.  I seem to remember that there isn't anything below 130 nm running on 6" wafers except for an IBM MEMs research facility in Switzerland.

Given the tiny die size, and the large transistor node I find the 2.5 GH/s implication very unlikely.

If someone has some serious photoshop skills it would be interesting to see what all the writing is on the opposite side of the tag.