Soft errors in SRAM devices induced by high energy neutrons, thermal neutrons and alpha particles

We measured the soft error rates (SER) of SRAM devices in several field tests, and obtained SERs induced independently by high energy neutrons, thermal neutrons and alpha particles. It was found that the thermal neutron induced SER was approximately three times larger than the high energy neutron induced SER in 0.18 /spl mu/m 8M SRAMs, and that the alpha particle induced SER was negligible. We also performed accelerated tests for thermal neutrons using a nuclear reactor, and found that the thermal neutron induced SER can be reduced by factors of up to several hundreds by using thermal neutron shield sheets or by eliminating BPSG layers.