Influence of diffused boron into MgO barrier on pinhole creation in CoFeB/MgO/CoFeB magnetic tunnel junctions

Koujiro Komagaki, Masashi Hattori, Kenji Noma, Hitoshi Kanai, Kazuo Kobayashi, Yuji Uehara, Masakiyo Tsunoda, Migaku Takahashi

Research output: Contribution to journalArticlepeer-review

15 Citations (Scopus)

Abstract

A relationship between boron (B) diffusion into the MgO barrier and pinhole creation in CoFeB/MgO/CoFeB-magnetic tunnel junctions (MTJs) was investigated. The diffused B in the MgO layer was identified by secondary ion mass spectrometry for the MTJs annealed at 350° C, which provide the giant magnetoresistance (TMR) ratio. The pinhole density, estimated from the statistic distribution of break - down voltage of the TMR properties, increased as either the thickness or the B content of the CoFeB layer became thicker or higher. These experimental findings imply that the diffused B into the MgO barrier creates pinholes to short-circuit the tunnel conduction, since the amount of diffused B into the MgO barrier might be related to the total amount of the B content in the CoFeB layer. Three different techniques were found to be useful for the reduction of diffused B into the MgO barrier layer; usage of materials having boron affinity for capping layer, decrease of the total amount of B-content in CoFeB layer, and reduction of grain boundaries in the MgO barrier layer.

Original languageEnglish
Article number5257009
Pages (from-to)3453-3456
Number of pages4
JournalIEEE Transactions on Magnetics
Volume45
Issue number10
DOIs
Publication statusPublished - 2009 Oct 1

Keywords

  • Brrier pinholes
  • CoFeB
  • Diffused boron
  • Grain boundary
  • In-situ heating
  • Magnetic tunnel junctions (MTJs)
  • MgO

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Electrical and Electronic Engineering

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