Phase change memory technology

TL;DR

This paper reviews the current state, physics, applications, challenges, and future prospects of phase change memory (PCM) technology, highlighting its rapid progress, key characteristics, and potential for high-density storage.

Contribution

It provides a comprehensive survey of PCM technology, including recent advancements, challenges, and future directions, with detailed analysis of physical principles and application considerations.

Findings

PCM has achieved significant scaling and large-array integration.

Key challenges include reducing RESET current and controlling variability.

Future prospects include multi-level cell technology and ultra-high density PCM.

Abstract

We survey the current state of phase change memory (PCM), a non-volatile solid-state memory technology built around the large electrical contrast between the highly-resistive amorphous and highly-conductive crystalline states in so-called phase change materials. PCM technology has made rapid progress in a short time, having passed older technologies in terms of both sophisticated demonstrations of scaling to small device dimensions, as well as integrated large-array demonstrators with impressive retention, endurance, performance and yield characteristics. We introduce the physics behind PCM technology, assess how its characteristics match up with various potential applications across the memory-storage hierarchy, and discuss its strengths including scalability and rapid switching speed. We then address challenges for the technology, including the design of PCM cells for low RESET current, the need to control device-to-device variability, and undesirable changes in the phase change material that can be induced by the fabrication procedure. We then turn to issues related to operation of PCM devices, including retention, device-to-device thermal crosstalk, endurance, and bias-polarity effects. Several factors that can be expected to enhance PCM in the future are addressed, including Multi-Level Cell technology for PCM (which offers higher density through the use of intermediate resistance states), the role of coding, and possible routes to an ultra-high density PCM technology.