Role of oxygen migration on the thermal stability of the perpendicular magnetic anisotropy in bottom and top structures

Wei Du,Mengli Liu,Hua Su,Bo Liu,Xiaoli Tang,Fengxuan Han,Huaiwu Zhang,Hao Meng

doi:10.1063/5.0076579

Abstract

The effect of interfacial oxygen migration on the thermal stability of the perpendicular magnetic anisotropy (PMA) in bottom and top structures was investigated in detail. By controlling the diffusion of thermally activated oxygen atoms, PMA with high thermal stability was achieved in the top structure. Compared with the bottom structure, the range of annealing temperature for which PMA was observed was extended to higher temperature (60 °C higher) via the strong Fe–O bonding in the top structure. Through detailed x-ray photoelectron spectroscopy analyses, the chemical states of different elements in CoFeB/MgO layers and the oxygen atom diffusion were investigated to understand the mechanisms behind the obtained high thermal stability of the PMA. It was found that the absence of thermally activated oxygen atom migration in the top structure is the main reason for the high thermal stability of the PMA. This study provides a promising way to obtain PMA with high thermal stability in CoFeB–MgO-based spintronic devices, which is significant to improve the compatibility of magnetic memories with the semiconductor integrated technology.

Highlights

Interfaces is due to the hybridization between the Fe/Co-3d and O-2p orbitals.10,11 A number of experiments involving interfacial chemical diffusion, annealing temperature, and different buffer or cap layers for CoFeB/MgO have been performed to manipulate the interfacial oxygen migration with the aim of achieving a higher perpendicular magnetic anisotropy (PMA) value
For the PMA-magnetic tunnel junction (MTJ), in addition to achieving large and stable PMA properties at room temperature, it is important to understand how to solve the issue of PMA degradation at temperatures exceeding 300 ○C; this is critical to increasing the compatibility of the PMA-MTJ with complementary metal–oxide–semiconductor (CMOS) integrated processes
A number of works investigated the relationship between the diffusion of different buffer or cap layers and the PMA in MTJ stacks via thermal annealing

Summary

Introduction

Interfaces is due to the hybridization between the Fe/Co-3d and O-2p orbitals.10,11 A number of experiments involving interfacial chemical diffusion, annealing temperature, and different buffer or cap layers for CoFeB/MgO have been performed to manipulate the interfacial oxygen migration with the aim of achieving a higher PMA value.1,12–15. Seldom work was attempted to investigate the impact of oxygen migration simultaneously in the bottom and top structures on the thermal stability scitation.org/journal/apm of the PMA.

Results

Conclusion