Diffusion behaviors observed on the surface of CoFeB film after the natural oxidation and the annealing

Soshi Sato, Hiroaki Honjo, Shoji Ikeda, Hideo Ohno, Tetsuo Endoh, Masaaki Niwa

Research output: Chapter in Book/Report/Conference proceedingConference contribution

Abstract

A magnetic tunnel junction (MTJ) with a CoFeB/MgO structure demonstrated a high tunnel magnetoresistance (TMR) ratio with a perpendicular magnetic easy axis1, and has been investigated toward an integration in VLSI2 to replace a conventional volatile cache memory with a magnetic random access memory3. A MgO tunnel barrier has been formed on a CoFeB film by a magnetron sputtering of MgO target4 or by a natural oxidation of Mg film5 to form a CoFeB/MgO stack. In both cases, the surface of the CoFeB film underneath has been found to be oxidized during MgO deposition process4,5 and to affect an interface perpendicular magnetic anisotropy5. A reduction of the oxidized Fe at the MgO/CoFeB interface was necessary to achieve a high TMR ratio6. In this experiment, a reduction reaction of oxidized Fe/Co by B on the naturally oxidized surface of the CoFeB film after an annealing has been investigated using X-ray photoelectron spectroscopy (XPS)7. In this work, we focused on the diffusion behaviors of the constituent elements at the CoFeB film surface after the natural oxidation and the annealing process to elucidate the oxidation and reduction mechanisms of the CoFeB film.

Original languageEnglish
Title of host publication2015 IEEE International Magnetics Conference, INTERMAG 2015
PublisherInstitute of Electrical and Electronics Engineers Inc.
ISBN (Electronic)9781479973224
DOIs
Publication statusPublished - 2015 Jul 14
Event2015 IEEE International Magnetics Conference, INTERMAG 2015 - Beijing, China
Duration: 2015 May 112015 May 15

Publication series

Name2015 IEEE International Magnetics Conference, INTERMAG 2015

Other

Other2015 IEEE International Magnetics Conference, INTERMAG 2015
CountryChina
CityBeijing
Period15/5/1115/5/15

ASJC Scopus subject areas

  • Surfaces, Coatings and Films
  • Electronic, Optical and Magnetic Materials
  • Electrical and Electronic Engineering

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