Shielding effect on secondary cosmic-ray neutron- and muon-induced soft errors

Abe, Shinichiro   ; Sato, Tatsuhiko   

Secondary cosmic-ray neutron have been recognized as a major cause of soft error for microelectronics on ground. Recently, the effect of secondary cosmic-ray muon on soft error is concerned as semiconductor devices become sensitive to radiation. In this study, we investigate the shielding effect on secondary cosmic-ray neutron- and muon-induced SER. Transports of secondary cosmic-ray neutrons and muons in a building are simulated by PHITS with considering distributions of energy and zenith-angle of secondary cosmic-rays by PARMA 4.0 which is the analytical model for estimating cosmic-ray fluxes nearly anytime and anywhere in the world. The calculated neutron fluxes are in surprisingly good agreement with measured data. The soft errors in 25-nm bulk-design NMOSFET caused by neutrons and muons in the open air and on the first floor of the building are analyzed based on the MSV model using PHITS. It is found that the shielding effect of the building only contributes to decrease neutron-induced SER. As a result, muon-induced SER is about 20% of that caused by neutron on the first floor. Therefore it is necessary to consider the secondary cosmic-ray muon-induced SER when reliability of devices used in the building is evaluated.