Dynamic moderation of an electric field using a SiO₂ switching layer in TaO_x -based ReRAM

ReRAMs using oxygen vacancy drift in their resistive switching are promising candidates as next generation memory devices. One remaining issue is degradation of the on/off ratio down to 10² or less with an increased number of switching cycles. Such degradation is caused by a local hard breakdown in a set process due to a very high electric field formed just before the completion of a conductive filament formation. We found that introducing an ultra-thin SiO₂ layer prevents the hard breakdown by dynamical moderation of the electric field formed in the TaO_x matrix, resulting in repeated switching while retaining a higher on/off ratio of about 10⁵.