Comparison between neutron-induced system-SER and accelerated-SER in SRAMS

The high energy neutron-induced SSER and ASER in SRAMs were compared, and a large discrepancy of a factor of 2.6 was observed. We investigated the possible causes of this discrepancy, including the accuracy of the neutron flux, the high flux effect, the incident neutron angle dependence, the temperature dependence, and the time variation of the cosmic rays, etc. As a result, we concluded that the discrepancy originates from the value assumed for the neutron flux at sea level. We normalized our ASER results to the SSER of 0.18 /spl mu/m SRAMs so as not to use the neutron flux at sea level. The SER of a 0.13 /spl mu/m 16 Mb SRAM is approximately 270 FIT/Mb.