Low-Current-Density Magnetic Tunnel Junctions for STT-RAM Application Using MgOxN1-x (x = 0.57) Tunnel Barrier

Mohamad G. Moinuddin; Aijaz H. Lone; Shivangi Shringi; Srikant Srinivasan; Satinder K. Sharma

doi:10.1109/TED.2019.2954131

Low-Current-Density Magnetic Tunnel Junctions for STT-RAM Application Using MgO_xN_1-x (x = 0.57) Tunnel Barrier

Mohamad G. Moinuddin, Aijaz H. Lone, Shivangi Shringi, Srikant Srinivasan^*, Satinder K. Sharma

^*Corresponding author for this work

Electrical and Computer Engineering

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

11 Scopus citations

Abstract

High switching speed, endurance, and low-current-based perpendicular magnetic tunnel junction (p-MTJ) memory is attracting wide interest as a key promising candidate for next-generation spintronic memory technology. p-MTJ-based spin-transfer torque RAM (STT-RAM) has been extensively investigated, and despite the promise, there is concern about the high switching current density and low stability with regard to scaling. In this work, the current controllability of p-MTJ in iron (Fe)-enriched Co₂₀Fe₆₀B₂₀ with a newly designed MgO_xN_1-x tunnel layer is systematically investigated, with the expectation that the introduction of N minimizes the oxidation of Fe to improve the performance of the device. A facile, plasma-based oxynitridation (MgO_{x= 0.57}N_1-x=0.43) of MgO through RF-sputter deposition serves as a reliable procedure to establish a tunnel barrier for an MTJ structure fabricated with 300-nm diameter and pinned with synthetic antiferromagnetic (SAF) [Co/Pt]_n multilayer stack. Current-controlled tunneling magnetoresistance (TMR) up to 65% was observed at room temperature (RT) with ultralow switching current density (J_c) of 136 ± 17 kA/cm². TMR along with tunnel conductance (g(V)) was measured to be highly stable in the read-bias regime (-200 to +200 mV) for MgO_xN_1-x as compared to the reported MgO barrier. The analogous MgO_xN_1-x-based MTJ structures were modeled using the nonequilibrium Green's function (NEGF) with appropriate tunnel barrier parameters and incorporating modulated barrier height as compared with the MgO barrier. The current-voltage characteristics of the modeled device showed close agreement with experimental data indicating high spin current. Based on the field-induced magnetization analysis, the macro-magnetic reversal analysis suggests the free-layer switching duration of 3 ns. These observations show the strong candidature of MgO_xN_1-x (x = 0.57) MTJs for STT-RAM device application.

Original language	English (US)
Article number	8935518
Pages (from-to)	125-132
Number of pages	8
Journal	IEEE TRANSACTIONS ON ELECTRON DEVICES
Volume	67
Issue number	1
DOIs	https://doi.org/10.1109/TED.2019.2954131
State	Published - Jan 2020

Bibliographical note

Funding Information:
Manuscript received September 10, 2019; revised November 4, 2019; accepted November 5, 2019. Date of publication December 17, 2019; date of current version December 30, 2019. The work of M. G. Moinuddin was supported by the Ministry of Electronics and Information Technology (MeitY), Government of India, through Visvesvaraya PhD Scheme. The review of this article was arranged by Editor G. L. Snider. (Corresponding author: Satinder K. Sharma.) The authors are with the School of Computing and Electrical Engineering (SCEE), Indian Institute of Technology (IIT) Mandi, Mandi 175005, India (e-mail: [email protected]; [email protected]).

Publisher Copyright:
© 1963-2012 IEEE.

Keywords

Low current density
oxynitrides
perpendicular magnetic tunnel junction (p-MTJ)
spintronics
tunnel barrier

ASJC Scopus subject areas

Electronic, Optical and Magnetic Materials
Electrical and Electronic Engineering

Access to Document

10.1109/TED.2019.2954131

Cite this

@article{1b2f9f9a42fb4c51b67d2a10f4d3f6e2,

title = "Low-Current-Density Magnetic Tunnel Junctions for STT-RAM Application Using MgOxN1-x (x = 0.57) Tunnel Barrier",

abstract = "High switching speed, endurance, and low-current-based perpendicular magnetic tunnel junction (p-MTJ) memory is attracting wide interest as a key promising candidate for next-generation spintronic memory technology. p-MTJ-based spin-transfer torque RAM (STT-RAM) has been extensively investigated, and despite the promise, there is concern about the high switching current density and low stability with regard to scaling. In this work, the current controllability of p-MTJ in iron (Fe)-enriched Co20Fe60B20 with a newly designed MgOxN1-x tunnel layer is systematically investigated, with the expectation that the introduction of N minimizes the oxidation of Fe to improve the performance of the device. A facile, plasma-based oxynitridation (MgOx= 0.57N1-x=0.43) of MgO through RF-sputter deposition serves as a reliable procedure to establish a tunnel barrier for an MTJ structure fabricated with 300-nm diameter and pinned with synthetic antiferromagnetic (SAF) [Co/Pt]n multilayer stack. Current-controlled tunneling magnetoresistance (TMR) up to 65% was observed at room temperature (RT) with ultralow switching current density (Jc) of 136 ± 17 kA/cm2. TMR along with tunnel conductance (g(V)) was measured to be highly stable in the read-bias regime (-200 to +200 mV) for MgOxN1-x as compared to the reported MgO barrier. The analogous MgOxN1-x-based MTJ structures were modeled using the nonequilibrium Green's function (NEGF) with appropriate tunnel barrier parameters and incorporating modulated barrier height as compared with the MgO barrier. The current-voltage characteristics of the modeled device showed close agreement with experimental data indicating high spin current. Based on the field-induced magnetization analysis, the macro-magnetic reversal analysis suggests the free-layer switching duration of 3 ns. These observations show the strong candidature of MgOxN1-x (x = 0.57) MTJs for STT-RAM device application.",

keywords = "Low current density, oxynitrides, perpendicular magnetic tunnel junction (p-MTJ), spintronics, tunnel barrier",

author = "Moinuddin, {Mohamad G.} and Lone, {Aijaz H.} and Shivangi Shringi and Srikant Srinivasan and Sharma, {Satinder K.}",

note = "Funding Information: Manuscript received September 10, 2019; revised November 4, 2019; accepted November 5, 2019. Date of publication December 17, 2019; date of current version December 30, 2019. The work of M. G. Moinuddin was supported by the Ministry of Electronics and Information Technology (MeitY), Government of India, through Visvesvaraya PhD Scheme. The review of this article was arranged by Editor G. L. Snider. (Corresponding author: Satinder K. Sharma.) The authors are with the School of Computing and Electrical Engineering (SCEE), Indian Institute of Technology (IIT) Mandi, Mandi 175005, India (e-mail: [email protected]; [email protected]). Publisher Copyright: {\textcopyright} 1963-2012 IEEE.",

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AU - Shringi, Shivangi

AU - Srinivasan, Srikant

AU - Sharma, Satinder K.

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N2 - High switching speed, endurance, and low-current-based perpendicular magnetic tunnel junction (p-MTJ) memory is attracting wide interest as a key promising candidate for next-generation spintronic memory technology. p-MTJ-based spin-transfer torque RAM (STT-RAM) has been extensively investigated, and despite the promise, there is concern about the high switching current density and low stability with regard to scaling. In this work, the current controllability of p-MTJ in iron (Fe)-enriched Co20Fe60B20 with a newly designed MgOxN1-x tunnel layer is systematically investigated, with the expectation that the introduction of N minimizes the oxidation of Fe to improve the performance of the device. A facile, plasma-based oxynitridation (MgOx= 0.57N1-x=0.43) of MgO through RF-sputter deposition serves as a reliable procedure to establish a tunnel barrier for an MTJ structure fabricated with 300-nm diameter and pinned with synthetic antiferromagnetic (SAF) [Co/Pt]n multilayer stack. Current-controlled tunneling magnetoresistance (TMR) up to 65% was observed at room temperature (RT) with ultralow switching current density (Jc) of 136 ± 17 kA/cm2. TMR along with tunnel conductance (g(V)) was measured to be highly stable in the read-bias regime (-200 to +200 mV) for MgOxN1-x as compared to the reported MgO barrier. The analogous MgOxN1-x-based MTJ structures were modeled using the nonequilibrium Green's function (NEGF) with appropriate tunnel barrier parameters and incorporating modulated barrier height as compared with the MgO barrier. The current-voltage characteristics of the modeled device showed close agreement with experimental data indicating high spin current. Based on the field-induced magnetization analysis, the macro-magnetic reversal analysis suggests the free-layer switching duration of 3 ns. These observations show the strong candidature of MgOxN1-x (x = 0.57) MTJs for STT-RAM device application.

AB - High switching speed, endurance, and low-current-based perpendicular magnetic tunnel junction (p-MTJ) memory is attracting wide interest as a key promising candidate for next-generation spintronic memory technology. p-MTJ-based spin-transfer torque RAM (STT-RAM) has been extensively investigated, and despite the promise, there is concern about the high switching current density and low stability with regard to scaling. In this work, the current controllability of p-MTJ in iron (Fe)-enriched Co20Fe60B20 with a newly designed MgOxN1-x tunnel layer is systematically investigated, with the expectation that the introduction of N minimizes the oxidation of Fe to improve the performance of the device. A facile, plasma-based oxynitridation (MgOx= 0.57N1-x=0.43) of MgO through RF-sputter deposition serves as a reliable procedure to establish a tunnel barrier for an MTJ structure fabricated with 300-nm diameter and pinned with synthetic antiferromagnetic (SAF) [Co/Pt]n multilayer stack. Current-controlled tunneling magnetoresistance (TMR) up to 65% was observed at room temperature (RT) with ultralow switching current density (Jc) of 136 ± 17 kA/cm2. TMR along with tunnel conductance (g(V)) was measured to be highly stable in the read-bias regime (-200 to +200 mV) for MgOxN1-x as compared to the reported MgO barrier. The analogous MgOxN1-x-based MTJ structures were modeled using the nonequilibrium Green's function (NEGF) with appropriate tunnel barrier parameters and incorporating modulated barrier height as compared with the MgO barrier. The current-voltage characteristics of the modeled device showed close agreement with experimental data indicating high spin current. Based on the field-induced magnetization analysis, the macro-magnetic reversal analysis suggests the free-layer switching duration of 3 ns. These observations show the strong candidature of MgOxN1-x (x = 0.57) MTJs for STT-RAM device application.

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