Neutron induced single-word multiple-bit upset in SRAM

The single-word multiple-bit upset (SMU) frequency for nine commercial static random access memories (SRAM) have been evaluated at eight different neutron energies; 0-11 MeV, 14 MeV, 22 MeV, 35 MeV, 45 MeV, 75 MeV, 96 MeV, 160 MeV. The SRAM types used at these experiments have sizes from 256 Kbit up to 1 Mbit, with date-codes ranging from 9209 up to 9809. The result showed a slightly rising dependence on the neutron energy. Also experiments at two neutron energies, 45 MeV and 96 MeV, were performed where the supply voltage influence on the SMU-rate was studied. Five device types were used at 96 MeV and the supply voltage was changed between 5 V, 3.3 V and 2.5 V. At 45 MeV three devices at 5 V and 3.3 V were irradiated. The experiments showed a relation between the amount of total upset and SMU that indicates no clear supply voltage dependence.