Reliability-aware cross-point resistive memory design

The transition metal oxide (TMO) resistive random access memory (ReRAM) has been identified as one of the most promising candidates for the next generation non-volatile memory (NVM) technology. Numerous TMO ReRAMs with different materials have been developed and demonstrate attractive characteristics, such as fast read/write speed, low power consumption, high integrated density, and good scalability. Among them, the most attractive characteristic of ReRAM is its cross-point structure which features a 4F² cell size. However, the existence of sneak current and voltage drop along the wire resistance in a cross-point array brings in extra design challenges. In addition, a robust ReRAM design needs to deal with both soft and hard errors. In this paper, we summarize mechanisms of both soft and hard errors of ReRAM cells and propose a unified model to characterize different failure behaviors. We quantitatively analyze the impact of cell failure modes on the reliability of cross-point array. We also propose an error resilient architecture which avoids unnecessary writes in the hard error detection unit. Experimental results show that our design can extend the lifetime of ReRAM up to 75% over the design without hard error detections and up to 12% over the design with "write-verify" detection mechanism.