Observation of boron diffusion in an annealed Ta/CoFeB/MgO magnetic tunnel junction with standing-wave hard x-ray photoemission

A. A. Greer, A. X. Gray, Shun Kanai, Alexander Kaiser, Shigenori Ueda, Yoshiyuki Yamashita, C. Bordel, Gunnar K. Pálsson, Naoyuki Maejima, See‐Hun Yang,

Applied Physics Letters · 2012 · 70 citations · 19 references

Concepts

Abstract

The CoFeB/MgO system shows promise as a magnetic tunnel junction with perpendicular magnetization and low critical current densities for spin-torque driven magnetization switching. The distribution of B after annealing is believed to be critical to performance. We have studied the distribution of B in a Ta/Co0.2Fe0.6B0.2/MgO sample annealed at 300 °C for 1 h with standing-wave hard x-ray photoemission spectroscopy (SW-HXPS). Comparing experimental rocking curve data to x-ray optical calculations indicates diffusion of 19.5% of the B uniformly into the MgO and of 23.5% into a thin TaB interface layer. SW-HXPS is effective for probing depth distributions in such spintronic structures.

References

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