Heavy ion radiation effects on TiN/HfO2/W resistive random access memory

Resistive random access memory (ReRAM) is an attractive candidate for application in next-generation nonvolatile memory (NVM) devices for both aerospace and conventional commercial applications. ReRAM has several intrinsic advantages over other NVM technologies due to its simple metal-insulator-metal structure, high storage density, low power consumption, high switching speed, and high endurance. Most importantly, there are indications that ReRAM is an intrinsically radiation-hard device due to its defect-moderated, resistive switching mechanism and potentially well suited for applications in aerospace or other radiation intensive environments. We present a study of the effects of radiation on TiN/HfO2/W ReRAM devices carried out with a variety of ion sources, including He, N, Ne, and Ar, at fluences ranging from 10¹² to 10¹⁵ cm⁻². Multiple (15–16) devices were employed in each irradiation experiment. Half of the devices were programmed into high resistance states (HRS, off states) and the other half were programmed into low resistance states (LRS, on states) before radiation exposure. After radiation, the resistance of ReRAM devices in each state decreased with higher influence and with heavier ions. We observed spontaneous switching of the high resistance states of all devices to low resistance states following Ne and Ar radiation at a fluence of 10¹⁵ cm⁻². However, most devices remained functional after radiation. Forming voltage and initial resistance of fresh non-formed devices were also compared with non-irradiated devices. The effects of radiation on ReRAM switching are attributed to modified defect distributions within the conducting filament. The radiation-induced defect densities and the associated dependence on ion mass are discussed in terms of current defect-mediated switching models for TiN/HfO2/W ReRAM devices.