Incidence of multi-particle events on soft error rates caused by n-Si nuclear reactions

Neutron reactions with silicon nuclei can be responsible for much of the so ft errors rate (SER) observed, for instance, in high density memories. The nuclear reactions create ionizing particles that then can induce charge col lection at sensitive nodes. In many cases, the nuclear reaction produces a shower of ions. Models for the prediction of SER are much more complicated if all the simultaneously created ions must be considered. In this paper, w e examine the proportion of events in which a shower of particles is actual ly involved. Spallation reaction effects for incident neutrons in the 50-20 00 MeV energy range are analyzed using a simple spherical structure. Calcul ations are performed using BRIC (Bruyeres le Chatel Intra-nuclear Cascade), an improved version of HETC (High Energy Transport Code). The results show that the proportion of events actually due to showers is less than 2% of t he total number of SER's.