Improvement of reliability and speed of phase change memory devices with N7.9(Ge46.9Bi7.2Te45.9) films

J H Park,S L Cho,J H Kim,D H Ahn,J M Lee,D.-H Ko,S.-W Kim,Z Wu,D Ahn,S W Nam

doi:10.1063/1.4928447

Abstract

In this study, we propose a nitrogen-incorporated GeBiTe ternary phase of N7.9(Ge46.9Bi7.2Te45.9) as a phase change material for reliable PCM (Phase Change Memory) with high speed operation. We found that the N7.9(Ge46.9Bi7.2Te45.9) film shows the resistance value of 40 kΩ after annealing at 440oC for 10 minutes, which is much higher than the value of 3.4 kΩ in the case of conventional N7.0(Ge22.0Sb22.0Te56.0) films. A set operation time of 14 nsec was achieved in the devices due to the increased probability of the nucleation by the addition of the elemental Bi. The long data retention time of 10 years at 85oC on the base of 1% failure was obtained as the result of higher activation energy of 2.52 eV for the crystallization compared to the case of N7.0(Ge22.0Sb22.0Te56.0) film, in which the activation energy is 2.1 eV. In addition, a reset current reduction of 27% and longer cycles of endurance as much as 2 order of magnitude compared to the case of N7.0(Ge22.0Sb22.0Te56.0) were observed at a set operation time of 14 nsec. Our results show that N7.9(Ge46.9Bi7.2Te45.9) is highly promising for use as a phase change material in reliable PCMs with high performance and also in forthcoming storage class memory applications, too.

Highlights

As the computer and mobile systems perform faster and their usage grows, new approaches to develop nonvolatile memory technologies locating between memory and the storage hierarchy are needed
Our results show that N7.9(Ge46.9Bi7.2Te45.9) is highly promising for use as a phase change material in reliable Phase Change Memory (PCM) with high performance and in forthcoming storage class memory applications, too
We report on characteristics of nitrogen doped GeBiTe films that lie in the pseudo-binary line between GeTe and Bi2Te3 and their electrical properties in PCM devices, similar to that the one between GeTe and Sb2Te3 in GeSbTe

Summary

Introduction

As the computer and mobile systems perform faster and their usage grows, new approaches to develop nonvolatile memory technologies locating between memory and the storage hierarchy are needed. A set operation time of 14 nsec was achieved in the devices due to the increased probability of the nucleation by the addition of the elemental Bi. The long data retention time of 10 years at 85oC on the base of 1% failure was obtained as the result of higher activation energy of 2.52 eV for the crystallization compared to the case of N7.0(Ge22.0Sb22.0Te56.0) film, in which the activation energy is 2.1 eV.

Results

Conclusion