Alpha-particle-induced soft errors in dynamic memories

TLDR

Alpha particles emitted from trace uranium and thorium in packaging materials can upset data stored in dynamic RAMs and CCDs by traversing the memory array. When an alpha particle penetrates the die surface, it generates sufficient electron‑hole pairs near a storage node to trigger a random single‑bit error. Experimental measurements of material alpha activity and a physical soft‑error model were presented, highlighting implications for the future of dynamic memories.

Abstract

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.