Physics-Based Modeling Strategies of Phase-Change Random Access Memory

Phase-change random access memory (PCRAM) has been regarded as one of the most promising candidates for future “universal” memory due to its mature fabrication techniques and profitable commercialized prospect. To further improve its physical performance and exploit more application areas, it is imperative to develop a physically realistic model that can closely mimic the electrical, thermal, and phase-change mechanisms of PCRAM. Although plenty of phase-change memory models have been proposed during the last two decades, they were constructed from various physical principles and, thus, targeted for different practical applications. As a result, a comprehensive review to elucidate the state-of-the-art modeling strategies of PCRAMs based on their phase-change mechanisms and application targets remains mysterious. To address this issue, we here reviewed the reported modeling approaches of PCRAMs mainly in terms of the finite-element method, the physics-based analytical model, and compact modeling techniques. For each technique, its adopted strategies to simulate the electrothermal and phase-change processes of phase-change materials at the device level were elaborated, respectively, and their respective merits and drawbacks were also given. The application fields, for which these models suit, were eventually discussed.

I. Introduction

Phase-change random access memory (PCRAM) devices, associated with its companions such as resistive RAM (ReRAM), ferroelectric RAM (FeRAM), and magnetic RAM (MRAM), have recently been regarded as the most promising substitutions for conventional dynamic RAM (DRAM) and static RAM (SRAM). Previously successful application of phase-change materials (PCMs) on rewritable optical disks [1] has accumulated a wealth of knowledge regarding the optical-thermo properties of PCMs and corresponding fabrication techniques [2], [3]. Subsequent research on PCRAM devices has naturally inherited such heritage and, therefore, accelerated the commercialization of PCRAM prior to other nonvolatile RAMs [4]. The total number of phase-change memory-related research papers and technical patents published within the year 2021 already exceeded 1200 and 900, respectively, implying the bright future of PCRAMs.