Radioactive Nuclei Induced Soft Errors at Ground Level

The role of all natural alpha emitters on the soft-error rate of integrated circuits is quantified. The impact of seven materials is given in FIT per mass unit. For instance, platinum has an isotope that is a natural alpha emitter, which may increase the Soft Error Rate up to 53 FIT/ng. Moreover, secular equilibrium of uranium is simulated by a Monte Carlo method. Only 90 parts per trillion of uranium is enough to explain the emissivity of wafers. Simulations show the trends of the alpha SER with scaling from the 250 nm technology node down to the 90 nm node. The contribution of alpha particles emitted by impurities to the SER is shown to become more important as the feature size decreases.