STEM tomography study on structural features induced by MTJ processing

Masaaki Niwa, Kosuke Kimura, Toshinari Watanabe, Takanori Naijou, Hiroaki Honjo, Shoji Ikeda, Tetsuo Endoh

Research output: Contribution to journalArticle

Abstract

The structure of a magnetic tunnel junction (MTJ) patterned by reactive ion etching is investigated in detail. Using a scanning transmission electron microscope (STEM) and energy-dispersive X-ray spectroscopy (EDX) combined with electron beam tomography, the unknown 3D interface roughness of CoFeB/MgO/CoFeB was successfully observed. From the orthoslice image, the interface morphology revealed characteristic features influenced by the roughness of the underlying layer. In contrast, a uniform morphology was observed for the metal layers except for the oxidized outer periphery of the MTJ. Additionally, we demonstrate that redeposited material at every turn of the MTJ side wall during the MTJ etching can be observed three-dimensionally by identifying the constituent elements using an electron tomographic technique combined with EDX. This analysis demonstrates a promising method to clarify the cause of electrical shorting of the ultra-thin tunnel barrier in MTJs, the location of which is challenging to determine using conventional cross-sectional transmission electron microscopy (TEM).

Original languageEnglish
Article number724
JournalApplied Physics A: Materials Science and Processing
Volume124
Issue number10
DOIs
Publication statusPublished - 2018 Oct 1

ASJC Scopus subject areas

  • Chemistry(all)
  • Materials Science(all)

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