Reliability Risks Due to Faults Affecting Selectors of ReRAMs and Possible Solutions

Resistive Random Access Memories (ReRAMs) are considered amongst the most promising candidates to replace silicon-based memories. However, ReRAMs suffer from reliability issues associated to faults affecting their resistive elements and their selectors. In this paper, we analyze the effects of faults affecting the selectors of ReRAMs on the operation of the crossbar memory array. We show that a selector failing as a short can give rise to numerous errors on the ReRAM crossbar array. We show that a single selector failing as a short may cause up to 64 errors in memory cells sharing the same word line of the cell containing the faulty selector. Such a large number of errors exceeds the correction capability of ECCs usually adopted for ReRAM arrays. We then propose a low-cost approach to detect short faults affecting selectors of ReRAMs and to identify the bitline containing the cell whose selector is faulty. Such a bitline can then be properly deactivated and replaced by a spare one, in order to guarantee the memory correct operation in the field.