The total die area is approximately 324mm^2. The die is split in 4 - i.e. under the metal lid there are 4 dies in a square arrangement, each approx 9mm x 9mm with 5mm gap in between each one (for better heat dissipation and spreading).
AHa. That explains a lot. I already wondered why anyone would develop such a large die for bitcoin mining.
It really is only a ~100GH/s 81mm² die, with 4 of them in an MCM. Interesting, and probably a good idea.