Phase-Change Memory—Towards a Storage-Class Memory

TLDR

Phase‑change memory (PCM) has evolved over 15 years of research and is now poised as a storage‑class memory with performance and cost between NAND flash and DRAM, thanks to advances in device scaling, cell design, thermal engineering, material exploration, and multi‑level storage. The paper reviews the history of phase‑transforming chalcogenides and evaluates PCM as a storage‑type SCM with high density, endurance, write speeds, and retention, or a memory‑type SCM with fast read/write times, and highlights performance gains and future prospects to make PCM ubiquitous like NAND flash within a decade. The review discusses key findings on device dimensional scaling, cell design, thermal engineering, material exploration, and multi‑level storage that underpin PCM’s performance as a storage‑class memory.

Abstract

Phase-change memory (PCM) has undergone significant academic and industrial research in the last 15 years. After much development, it is now poised to enter the market as a storage-class memory (SCM), with performance and cost between that of NAND flash and DRAM. In this paper, we review the history of phase-transforming chalcogenides leading up to our current understanding of PCM as either a storage-type SCM, with high-density and better than NAND flash endurance, write speeds, and retention, or a memory-type SCM, with fast read/write times to function as a nonvolatile DRAM. Several of the key findings from the community relating to device dimensional scaling, cell design, thermal engineering, material exploration, and storing multiple levels per cell will be discussed. These areas have dramatically impacted the course of development and understanding of PCM. We will highlight the performance gains attained and the future prospects, which will help drive PCM to be as ubiquitous as NAND flash in the upcoming decade.