Lifetime enhancement of multi-level cell phase change memory

Abstract

Phase change memory (PCM) is a promising device for its good scalability and negligible standby power consumption. Multi-level cell (MLC) PCM allows higher memory density, but it suffers from reduced endurance due to frequent RESET operation during writing. Enhanced conditional RESET write (ECRW) method is proposed, in which intermediate states such as '01' and '10' are reached without RESET initialization. A new MLC PCM model is presented, which takes account of phase configuration of each MLC PCM state

the feasibility of ECRW is assessed using the model. Compression-based RESET removal encoding (CRE) is also proposed to further reduce the number of RESET operations. Experiments demonstrate that the proposed methods achieve $18.5\times$ enhancement of cell lifetime

the writing energy dissipation is reduced to 51.5% on average of test cases.