Current status of chalcogenide phase change memory

Non-volatile memories (NVM) are playing an important role in the semiconductor market, thanks in particular to flash which is used mainly in cellular phones and other types of electronic portable equipment. In the coming years portable systems will demand even more NVM with high density and very high writing throughput for data storage application, or with fast random access for code execution. Flash memory has followed the scaling evolution, of the semiconductor map since its introduction in the late '80's but further scaling is becoming increasingly complex as some of the fundamental physical limitations are being approached. While continued research on floating gate techniques should extend the current flash technology capability through the end of this decade, there is increasing interest in new memory storage mechanisms and materials that have promise for scaling through at least the end of the next decade. Among the different NVM based on storage mechanisms alternative to the floating gate concept, phase-change memories (PCM), also called ovionic unified memory (OUM),is one of the most promising candidates, having the potential to improve the performance compared to flash as well as to be scalable beyond flash technology (Lai and Lowrey (2001), Lai (2003), Bez (2004)), In this review, the physics and operation of phase change memory is first presented, followed by discussion of current status of development. Finally, the scaling capability of the technology is absent