The Influence of Capping Layers on Tunneling Magnetoresistance and Microstructure in CoFeB/MgO/CoFeB Magnetic Tunnel Junctions upon Annealing

Geunwoo Kim; Soogil Lee; Sanghwa Lee; Byonggwon Song; Byung Kyu Lee; Duhyun Lee; Jin Seo Lee; Min Hyeok Lee; Young Keun Kim; Byong Guk Park

doi:10.3390/nano13182591

The Influence of Capping Layers on Tunneling Magnetoresistance and Microstructure in CoFeB/MgO/CoFeB Magnetic Tunnel Junctions upon Annealing

Geunwoo Kim, Soogil Lee, Sanghwa Lee, Byonggwon Song, Byung Kyu Lee, Duhyun Lee, Jin Seo Lee, Min Hyeok Lee, Young Keun Kim, Byong Guk Park

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

2 Citations (Scopus)

Abstract

This study investigates the effects of annealing on the tunnel magnetoresistance (TMR) ratio in CoFeB/MgO/CoFeB-based magnetic tunnel junctions (MTJs) with different capping layers and correlates them with microstructural changes. It is found that the capping layer plays an important role in determining the maximum TMR ratio and the corresponding annealing temperature (T_ann). For a Pt capping layer, the TMR reaches ~95% at a T_ann of 350 °C, then decreases upon a further increase in T_ann. A microstructural analysis reveals that the low TMR is due to severe intermixing in the Pt/CoFeB layers. On the other hand, when introducing a Ta capping layer with suppressed diffusion into the CoFeB layer, the TMR continues to increase with T_ann up to 400 °C, reaching ~250%. Our findings indicate that the proper selection of a capping layer can increase the annealing temperature of MTJs so that it becomes compatible with the complementary metal-oxide-semiconductor backend process.

Original language	English
Article number	2591
Journal	Nanomaterials
Volume	13
Issue number	18
DOIs	https://doi.org/10.3390/nano13182591
Publication status	Published - 2023 Sept

Bibliographical note

Publisher Copyright:
© 2023 by the authors.

Keywords

capping layer
diffusion
magnetic tunnel junction
tunneling magnetoresistance

ASJC Scopus subject areas

General Chemical Engineering
General Materials Science

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title = "The Influence of Capping Layers on Tunneling Magnetoresistance and Microstructure in CoFeB/MgO/CoFeB Magnetic Tunnel Junctions upon Annealing",

abstract = "This study investigates the effects of annealing on the tunnel magnetoresistance (TMR) ratio in CoFeB/MgO/CoFeB-based magnetic tunnel junctions (MTJs) with different capping layers and correlates them with microstructural changes. It is found that the capping layer plays an important role in determining the maximum TMR ratio and the corresponding annealing temperature (Tann). For a Pt capping layer, the TMR reaches ~95% at a Tann of 350 °C, then decreases upon a further increase in Tann. A microstructural analysis reveals that the low TMR is due to severe intermixing in the Pt/CoFeB layers. On the other hand, when introducing a Ta capping layer with suppressed diffusion into the CoFeB layer, the TMR continues to increase with Tann up to 400 °C, reaching ~250%. Our findings indicate that the proper selection of a capping layer can increase the annealing temperature of MTJs so that it becomes compatible with the complementary metal-oxide-semiconductor backend process.",

keywords = "capping layer, diffusion, magnetic tunnel junction, tunneling magnetoresistance",

author = "Geunwoo Kim and Soogil Lee and Sanghwa Lee and Byonggwon Song and Lee, {Byung Kyu} and Duhyun Lee and Lee, {Jin Seo} and Lee, {Min Hyeok} and Kim, {Young Keun} and Park, {Byong Guk}",

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year = "2023",

month = sep,

doi = "10.3390/nano13182591",

language = "English",

volume = "13",

journal = "Nanomaterials",

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AU - Kim, Geunwoo

AU - Lee, Soogil

AU - Lee, Sanghwa

AU - Song, Byonggwon

AU - Lee, Byung Kyu

AU - Lee, Duhyun

AU - Lee, Jin Seo

AU - Lee, Min Hyeok

AU - Kim, Young Keun

AU - Park, Byong Guk

PY - 2023/9

Y1 - 2023/9

N2 - This study investigates the effects of annealing on the tunnel magnetoresistance (TMR) ratio in CoFeB/MgO/CoFeB-based magnetic tunnel junctions (MTJs) with different capping layers and correlates them with microstructural changes. It is found that the capping layer plays an important role in determining the maximum TMR ratio and the corresponding annealing temperature (Tann). For a Pt capping layer, the TMR reaches ~95% at a Tann of 350 °C, then decreases upon a further increase in Tann. A microstructural analysis reveals that the low TMR is due to severe intermixing in the Pt/CoFeB layers. On the other hand, when introducing a Ta capping layer with suppressed diffusion into the CoFeB layer, the TMR continues to increase with Tann up to 400 °C, reaching ~250%. Our findings indicate that the proper selection of a capping layer can increase the annealing temperature of MTJs so that it becomes compatible with the complementary metal-oxide-semiconductor backend process.

AB - This study investigates the effects of annealing on the tunnel magnetoresistance (TMR) ratio in CoFeB/MgO/CoFeB-based magnetic tunnel junctions (MTJs) with different capping layers and correlates them with microstructural changes. It is found that the capping layer plays an important role in determining the maximum TMR ratio and the corresponding annealing temperature (Tann). For a Pt capping layer, the TMR reaches ~95% at a Tann of 350 °C, then decreases upon a further increase in Tann. A microstructural analysis reveals that the low TMR is due to severe intermixing in the Pt/CoFeB layers. On the other hand, when introducing a Ta capping layer with suppressed diffusion into the CoFeB layer, the TMR continues to increase with Tann up to 400 °C, reaching ~250%. Our findings indicate that the proper selection of a capping layer can increase the annealing temperature of MTJs so that it becomes compatible with the complementary metal-oxide-semiconductor backend process.

KW - capping layer

KW - diffusion

KW - magnetic tunnel junction

KW - tunneling magnetoresistance

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DO - 10.3390/nano13182591

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The Influence of Capping Layers on Tunneling Magnetoresistance and Microstructure in CoFeB/MgO/CoFeB Magnetic Tunnel Junctions upon Annealing

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