  Heavy ions induced single event upset (SEU) sensitivity of three-dimensional
integrated SRAMs are evaluated by using Monte Carlo sumulation methods based on
Geant4. The cross sections of SEUs and Multi Cell Upsets (MCUs) for 3D SRAM are
simulated by using heavy ions with different energies and LETs. The results
show that the sensitivity of different die of 3D SRAM has obvious discrepancies
at low LET. Average percentage of MCUs of 3D SRAMs rises from 17.2% to 32.95%
when LET increases from 42.19 MeV cm2/mg to 58.57MeV cm2/mg. As for a certain
LET, the percentage of MCUs shows a notable distinction between face-to-face
structure and back-to-face structure. For back-to-face structure, the
percentage of MCUs increases with the deeper die. However, the face-to-face die
presents the relatively low percentage of MCUs. The comparison of SEU cross
sections for planar SRAMs and experiment data are conducted to indicate the
effectiveness of our simulation method. Finally, we compare the upset cross
sections of planar process and 3D integrated SRAMs. Results demonstrate that
the sensitivity of 3D SRAMs is not more than that of planar SRAMs and the 3D
structure can be become a great potential application for aerospace and
military domain.
