A novel self-converging write scheme for 2-bits/cell phase change memory for Storage Class Memory (SCM) application

A new phase change material that provides fast SET speed, high cycling endurance, and large resistance window suitable for MLC SCM is investigated. Thorough understanding of the factors that affect the resistance distribution taught us to avoid operating near the melting temperature of the phase change material. By exploiting the self-converging property of low current SET operation we have designed a novel write scheme that provides fast and accurate MLC programming. High performance and high reliability 2-bits/cell MLC is demonstrated on a 512Mb test chip.