Heavy-Ion Radiation Effects in 3D NAND Flash Memory: Impact of Cell Scaling

With the increasing demand for reliable non-volatile memory technologies in space applications, 3D Charge Trap NAND Flash memory has emerged as a promising solution due to its high density and scalability. However, spaceborne electronics are exposed to ionizing radiation from solar particles and galactic cosmic rays, which can induce single event effects and compromise stored data. This thesis investigates the response of 3D Charge Trap NAND Flash memories to heavy-ion irradiation, with particular attention on the impact of memory-cell scaling. Experimental studies were performed on research-grade 3D NAND devices provided by Micron. The work first reviews the operating principles of NAND Flash memory and its scaling evolution from planar architectures to modern vertical 3D structures. It then introduces the mechanisms of ionizing radiation and single-event effects in semiconductor memories. The results of heavy-ion irradiation experiments were analyzed to evaluate threshold voltage shifts induced in memory cells under different radiation conditions. The effects of ion linear energy transfer (LET), programmed threshold-voltage level, ion incidence angle, and cell geometry scaling were analyzed using extensive threshold-voltage measurements collected before and after irradiation. The results demonstrate that ion LET is the primary factor governing device sensitivity to heavy-ion exposure. Cell diameter scaling was found to have a negligible impact on radiation-induced threshold-voltage shifts, whereas a reduction in cell tier pitch led to increased vulnerability to heavy-ion effects. These findings provide insight into the radiation effects of scaled 3D NAND Flash technologies and support their potential for future space applications.