Alpha-particle-induced soft errors in dynamic memories

A new physical soft error mechanism in dynamic RAM´s and CCD´s is the upset of stored data by the passage of alpha particles through the memory array area. The alpha particles are emitted by the radioactive decay of uranium and thorium which are present in parts-per-million levels in packaging materials. When an alpha particle penetrates the die surface, it can create enough electron-hole pairs near a storage node to cause a random, single-bit error. Results of experiments and measurements of alpha activity of materials are reported and a physical model for the soft error is developed. Implications for the future of dynamic memories are also discussed.