Effect of scaling on thermal properties and switching operation of phase change memory devices

Jie Zhu,Zuoqi Hu,Changcheng Ma,Jingjing Lu,Jing He,Cheng-Chi Wang

doi:10.1051/matecconf/201820106002

Abstract

Phase change memory (PCM) is one of the most promising emerging non-volatile memory technologies. This paper simulates phase change memory devices (PCMDs) with careful attention to the scaling and its resulting impact on programming current during the switching operation, while Thomson heating within the phase change material and Peltier heating at the electrode interface are considered. The simulation results show that the device scaling has an influence on temperature distribution, volume of the molten region, heat diffusion and switching operation of PCMDs. The programming current decreases with smaller electrode size, greater thickness of phase change material and deeper isotropic scaling. The heat diffusion becomes more serious when the thickness of phase change materials decreases and the size of PCMD is isotropically scaled down. The scaling arguments also indicate that the impact of thermoelectric phenomena weakens with smaller dimensions due to the influence of programming current, heat diffusion and action area. This simulation provides useful insights to understand the switching operation of the PCMDs under the impact of thermoelectric effects. The process is instrumental for a complete understanding of device operation and hence provides valuable feedback for fine-tuning the device design so as to enhance its efficiency.

Highlights

To date, phase change memory (PCM) is one of the most promising emerging non-volatile memory technologies due to its fast programming speed, exceptional endurance and capability of scaling [1,2,3]
In terms of a phase change memory device (PCMD), with the application of bias voltage the information can be programmed by a non-volatile phase transition of phase change materials, especially some chalcogenide materials like GST [2,4]
With the thickness of GST layer scaled down, the ratio of current reduction caused by Peltier effect decreases and the ratio of current reduction caused by Thomson effect slightly increases

Summary

Introduction

Phase change memory (PCM) is one of the most promising emerging non-volatile memory technologies due to its fast programming speed, exceptional endurance and capability of scaling [1,2,3]. The phase change material can be switched from a low-resistance crystalline state, set state as well, to a high-resistance amorphous state, namely reset state, because of the Joule heating [5]. The reset operation is considered as a Gordian knot for research of PCM, owing to the requirement of a relatively high current, which is limited by the minimal size of devices and the possibility of parallel programming in an array. It is essential that thermoelectric heating should be considered in studying the switching operation in PCM devices. This paper simulates PCMD aiming at studying the relationship between the scaling and its resulting impact on programming current during the switching operation, while thermoelectric effects are considered

Results

Discussion

Conclusion