Investigation Into the Degradation of DDR4 DRAM Owing to Total Ionizing Dose Effects

Abstract

Total ionizing dose (TID) effects of gamma rays were investigated on DDR4 dynamic random access memory (DRAM) and analyzed using TCAD simulations. In this study, we considered the operating states, dose rates, temperatures, and annealing to analyze the impact of TID under different conditions. The worst degradation was observed in the operated state and at a low-dose rate because of the absence of an electrostatic barrier that reduced the possibility of interface trap formation under unbiased and high-dose rate conditions. At lower temperatures, the effects of radiation were mitigated by the reduced production of protons (H + ). In addition, the unbiased DRAM and high-temperature conditions are the fastest to recover during postirradiation annealing. In TCAD simulations, the retention time decreased with increasing temperature because the band-to-band tunneling (BTBT) generation increased. Furthermore, the retention time and row activation latency (tRCD) degraded as the concentration of the interface traps increased. This is because the interface traps caused leakage currents and hindered the flow of electrons.