Dependence of tunnel magnetoresistance in MgO based magnetic tunnel junctions on Ar pressure during MgO sputtering

Shoji Ikeda, Jun Hayakawa, Young Min Lee, Ryutaro Sasaki, Toshiyasu Meguro, Fumihiro Matsukura, Hideo Ohno

Research output: Contribution to journalArticlepeer-review

98 Citations (Scopus)

Abstract

We investigated dependence of tunnel magnetoresistance effect in CoFeB/MgO/CoFeB magnetic tunnel junctions on Ar pressure during MgO-barrier sputtering. Sputter deposition of MgO-barrier at high Ar pressure of 10 mTorr resulted in smooth surface and highly (001) oriented MgO. Using this MgO as a tunnel barrier, tunnel magnetoresistance (TMR) ratio as high as 355% at room temperature (578% at 5 K) was realized after annealing at 325°C or higher, which appears to be related to a highly (001) oriented CoFeB texture promoted by the smooth and highly oriented MgO. Electron-beam lithography defined deep-submicron MTJs having a low-resistivity Au underlayer with the high-pressure deposited MgO showed high TMR ratio at low resistance-area product (RA) below 10 ω μm2 as 27% at RA = 1.1 ω μm 2, 77% at RA = 1.1 ω μm2, 130% at RA = 1.7 ω μm2, and 165% at RA = 2.9 ω μm2.

Original languageEnglish
Pages (from-to)L1442-L1445
JournalJapanese Journal of Applied Physics, Part 2: Letters
Volume44
Issue number46-49
DOIs
Publication statusPublished - 2005 Nov 25

Keywords

  • CoFeB
  • MgO barrier
  • Resistance
  • Sputtering pressure
  • Tunnel magnetoresistance

ASJC Scopus subject areas

  • Engineering(all)
  • Physics and Astronomy (miscellaneous)
  • Physics and Astronomy(all)

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