Evaluation of fast neutron induced single event upset in a static random access memory and simulation by Monte Carlo N-Particle Code (MCNPX)

Neutron-induced single-event upsets (SEUs) in a 0.4 mum 4Mbit CMOS SRAM (complimentary metal oxide semiconductor static random access memory) were investigated using high-energy neutron beams and Monte Carlo simulation by MCNPX (Monte Carlo N-Particle Code). The Monte Carlo simulation, based on the assumption that the primary cause of SEUs is alpha particles generated by nuclear fission, agreed with the experimental results within the accuracy of +/-29% in the case of small cell charges (< 10 fC). When the devices were exposed to fast neutrons in the front-surface direction, the SEU rates increased by a factor of 1.1 to 2 in comparison with the case of back-surface irradiation. According to the Monte Carlo simulation, the difference between the alpha particle production cross section of the carbon atom in package materials and that of the silicon atom caused this phenomenon.