Characterizing Energetic Dependence of Low-Energy Neutron-induced MCUs in 65 nm bulk SRAMs

This paper studies the characteristic of MCUs induced by monoenergetic and quasi-monoenergetic low-energy neutrons in 65-nm SRAM. This work is highlighted with the characterized dependence of the MCU cross section on the neutron energy, whereas the evaluated energy dependence of the SEU cross section was consistent with the literature. Both the MCU cross section and its proportion to the total events increase with higher neutron energy. At the onset energy of 6.0 MeV, the MCU proportion is 51 %, while the maximum value of 66 % is at 70 MeV. On the other hand, even at a lower energy of 4.1 MeV, the MCU proportion keeps around 50 %. The high MCU proportion over the wide range of neutron energy suggests the possibility of large-LET secondary ions being generated even by 4.1 MeV neutrons. Also, based on the measured MCU dependence, we calculated the contribution of the low-energy neutron to the total SER of MCU. The calculated result indicates that the low-energy neutrons below 10 MeV are mostly negligible in the terrestrial environment.