Surface flattening processes of metal layer and their effect on transport properties of magnetic tunnel junctions with Al-N barrier

S. Yoshimura; T. Nozawa; T. Shoyama; M. Tsunoda; M. Takahashi

doi:10.1063/1.1854452

Surface flattening processes of metal layer and their effect on transport properties of magnetic tunnel junctions with Al-N barrier

S. Yoshimura, T. Nozawa, T. Shoyama, M. Tsunoda, M. Takahashi

Research output: Contribution to journal › Article › peer-review

Abstract

In order to form ultrathin insulating layer in magnetic tunnel junctions (MTJs), two surface flatting processes of metal films are investigated. Oxygen-additive sputter-deposition process was applied to the bottom Cu electrode and the Al layer to be nitrided. Dry-etching process was applied for the surface treatment of lower Co-Fe layer. As a result, the surface roughness of stacked ultrathin Al layer to be nitrided is reduced from 3.2Å to 1.7Å, and the tunnel magnetoresistance (TMR) ratio of the MTJs increases from 1% to 26% while maintaining resistance-area product (R×A) less than 5× 102 ω μ m2 in the Co-FeAl (6A) -NCo-Fe MTJs. We conclude that the decrease of the surface roughness of Al layer is one of the key factors to realize high performance MTJs with low R×A and high TMR ratio.

Original language	English
Article number	10C920
Journal	Journal of Applied Physics
Volume	97
Issue number	10
DOIs	https://doi.org/10.1063/1.1854452
Publication status	Published - 2005 May 15
Externally published	Yes

ASJC Scopus subject areas

Physics and Astronomy(all)

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title = "Surface flattening processes of metal layer and their effect on transport properties of magnetic tunnel junctions with Al-N barrier",

abstract = "In order to form ultrathin insulating layer in magnetic tunnel junctions (MTJs), two surface flatting processes of metal films are investigated. Oxygen-additive sputter-deposition process was applied to the bottom Cu electrode and the Al layer to be nitrided. Dry-etching process was applied for the surface treatment of lower Co-Fe layer. As a result, the surface roughness of stacked ultrathin Al layer to be nitrided is reduced from 3.2{\AA} to 1.7{\AA}, and the tunnel magnetoresistance (TMR) ratio of the MTJs increases from 1% to 26% while maintaining resistance-area product (R×A) less than 5× 102 ω μ m2 in the Co-FeAl (6A) -NCo-Fe MTJs. We conclude that the decrease of the surface roughness of Al layer is one of the key factors to realize high performance MTJs with low R×A and high TMR ratio.",

author = "S. Yoshimura and T. Nozawa and T. Shoyama and M. Tsunoda and M. Takahashi",

note = "Funding Information: This study was supported by the IT-program of Research Revolution 2002 (Grant No. RR2002) “Development of Universal Low-Power Spin Memory” from the Ministry of Education, Culture, Sports, Science and Technology of Japan.",

year = "2005",

month = may,

day = "15",

doi = "10.1063/1.1854452",

language = "English",

volume = "97",

journal = "Journal of Applied Physics",

issn = "0021-8979",

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T1 - Surface flattening processes of metal layer and their effect on transport properties of magnetic tunnel junctions with Al-N barrier

AU - Yoshimura, S.

AU - Nozawa, T.

AU - Shoyama, T.

AU - Tsunoda, M.

AU - Takahashi, M.

N1 - Funding Information: This study was supported by the IT-program of Research Revolution 2002 (Grant No. RR2002) “Development of Universal Low-Power Spin Memory” from the Ministry of Education, Culture, Sports, Science and Technology of Japan.

PY - 2005/5/15

Y1 - 2005/5/15

N2 - In order to form ultrathin insulating layer in magnetic tunnel junctions (MTJs), two surface flatting processes of metal films are investigated. Oxygen-additive sputter-deposition process was applied to the bottom Cu electrode and the Al layer to be nitrided. Dry-etching process was applied for the surface treatment of lower Co-Fe layer. As a result, the surface roughness of stacked ultrathin Al layer to be nitrided is reduced from 3.2Å to 1.7Å, and the tunnel magnetoresistance (TMR) ratio of the MTJs increases from 1% to 26% while maintaining resistance-area product (R×A) less than 5× 102 ω μ m2 in the Co-FeAl (6A) -NCo-Fe MTJs. We conclude that the decrease of the surface roughness of Al layer is one of the key factors to realize high performance MTJs with low R×A and high TMR ratio.

AB - In order to form ultrathin insulating layer in magnetic tunnel junctions (MTJs), two surface flatting processes of metal films are investigated. Oxygen-additive sputter-deposition process was applied to the bottom Cu electrode and the Al layer to be nitrided. Dry-etching process was applied for the surface treatment of lower Co-Fe layer. As a result, the surface roughness of stacked ultrathin Al layer to be nitrided is reduced from 3.2Å to 1.7Å, and the tunnel magnetoresistance (TMR) ratio of the MTJs increases from 1% to 26% while maintaining resistance-area product (R×A) less than 5× 102 ω μ m2 in the Co-FeAl (6A) -NCo-Fe MTJs. We conclude that the decrease of the surface roughness of Al layer is one of the key factors to realize high performance MTJs with low R×A and high TMR ratio.

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Surface flattening processes of metal layer and their effect on transport properties of magnetic tunnel junctions with Al-N barrier

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