Radiation Induced Charge Loss Mechanisms Across the Dielectrics of Floating Gate Flash Memories

One of the key factors permitting the extraordinary success offloating gate (FG) nonvolatile memories relies on the excellentinsulating properties of the dielectric layers surrounding theFG itself. Among other threats, ionizing radiation mayeffectively affect such insulating characteristics, leading to adegradation of the FG stored charge. Radiation effects have beentraditionally studied for niche applications such as the highenergy physics or the satellite industry. However, modernsemiconductor technologies are becoming more and more sensitiveto the deposition of small amounts of charge, such as thosegenerated by the byproducts of atmospheric neutrons, and FGmemories are in fact aggressively scaled following Moore's lawpredictions. Loss of information may derive from two broadcategories of phenomena, Total Ionizing Dose and Single EventEffect, whose actions on the FG dielectrics are reviewed in thiscontribution from the viewpoints of the prompt induced damageand long-term degradation effects, affecting the memoryretention capabilities.