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

doi:10.1143/JJAP.44.L1442

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 journal › Article › peer-review

107 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 language	English
Pages (from-to)	L1442-L1445
Journal	Japanese Journal of Applied Physics, Part 2: Letters
Volume	44
Issue number	46-49
DOIs	https://doi.org/10.1143/JJAP.44.L1442
Publication status	Published - 2005 Nov 25

Keywords

CoFeB
MgO barrier
Resistance
Sputtering pressure
Tunnel magnetoresistance

ASJC Scopus subject areas

Engineering(all)
Physics and Astronomy(all)

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10.1143/JJAP.44.L1442

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title = "Dependence of tunnel magnetoresistance in MgO based magnetic tunnel junctions on Ar pressure during MgO sputtering",

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.",

keywords = "CoFeB, MgO barrier, Resistance, Sputtering pressure, Tunnel magnetoresistance",

author = "Shoji Ikeda and Jun Hayakawa and Lee, {Young Min} and Ryutaro Sasaki and Toshiyasu Meguro and Fumihiro Matsukura and Hideo Ohno",

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doi = "10.1143/JJAP.44.L1442",

language = "English",

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T1 - Dependence of tunnel magnetoresistance in MgO based magnetic tunnel junctions on Ar pressure during MgO sputtering

AU - Ikeda, Shoji

AU - Hayakawa, Jun

AU - Lee, Young Min

AU - Sasaki, Ryutaro

AU - Meguro, Toshiyasu

AU - Matsukura, Fumihiro

AU - Ohno, Hideo

PY - 2005/11/25

Y1 - 2005/11/25

N2 - 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.

AB - 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.

KW - CoFeB

KW - MgO barrier

KW - Resistance

KW - Sputtering pressure

KW - Tunnel magnetoresistance

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

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