A Survey on PCM Lifetime Enhancement Schemes

Phase Change Memory (PCM) is an emerging memory technology that has the capability to address the growing demand for memory capacity and bridge the gap between the main memory and the secondary storage. As a resistive memory, PCM is able to store data based on its resistance values. The wide resistance range of PCM makes it possible to store even multiple bits per cell (MLC) rather than a single bit per cell (SLC). Unfortunately, PCM cells suffer from short lifetime. That means PCM cells could tolerate a limited number of write operations, and afterward they tend to permanently stick at a constant value. Limited lifetime is an issue related to PCM memory; hence, in recent years, many studies have been conducted to prolong PCM lifetime. These schemes have vast variety and are applied at different architectural levels. In this survey, we review the important works of such schemes to give insights to those starting to research on non-volatile memories (NVMs). These schemes are not limited to PCM and are applicable on other NVM technologies due to the similarities between them and the generality of lifetime-prolonging schemes.