The Effects of Neutron Energy and High-Z Materials on Single Event Upsets and Multiple Cell Upsets

Neutron-induced charge collection data and computer simulations presented here show that the presence of high-Z materials, like tungsten, can increase the single event upset (SEU) and multiple cell upset (MCU)cross sections of high critical charge (Q_crit) devices exposed to the terrestrial neutron environment because of interactions with high energy ( >; 100 MeV) neutrons. Time-of-flight data and computer simulations presented here demonstrate that 14 MeV neutrons do not produce highly ionizing secondary particles. Thus, 14 MeV neutrons can only simulate the SEU response of 65 nm SRAM devices in the terrestrial neutron environment for devices with a Q_crit <; 27fC, and can simulate the 2-bit MCU response to within a factor of two only for very low Q_crit devices, <; 1.2 fC.Additionally, it is shown that 14 MeV neutrons cannot adequately simulate the 3 or more bit MCU response for typical 65 nm SRAM devices.