# US 12,004,355 B2 · Magnetic tunnel junction element and magnetoresistive memory device

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- Number: US 12,004,355 B2
- Document ID: US12004355B2
- Status: Granted
- Kind: B2
- Application number: 17/498,023
- Filed: 2021-10-11
- Published: 2022-04-28
- Granted: 2024-06-04
- Earliest claimed: 2020-10-23
- Assignees: Samsung Electronics Co., Ltd.
- Applicants: Samsung Electronics Co., Ltd.
- Inventors: Yoshiaki Sonobe; Hideto Yanagihara
- Web page: https://patentgrep.com/patent/US12004355B2

## CPC

- H10B 61/00: Magnetic memory devices, e.g. magnetoresistive RAM [MRAM] devices
- H01F 10/3254: {the spacer being semiconducting or insulating, e.g. for spin tunnel junction [STJ]}
- H01F 10/3268: {the exchange coupling being asymmetric, e.g. by use of additional pinning, by using antiferromagnetic or ferromagnetic coupling interface, i.e. so-called spin-valve [SV] structure, e.g. NiFe/Cu/NiFe/FeMn}
- H01F 10/3286: {Spin-exchange coupled multilayers having at least one layer with perpendicular magnetic anisotropy}
- H10N 50/10: Magnetoresistive devices
- H10N 50/80: Constructional details
- H10N 50/85: Materials of the active region
- H01F 10/329: {Spin-exchange coupled multilayers wherein the magnetisation of the free layer is switched by a spin-polarised current, e.g. spin torque effect}
- H10B 61/22: {of the field-effect transistor [FET] type}
- H10B: ELECTRONIC MEMORY DEVICES
- H01F: MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
- H10N: ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR

## Abstract

Provided is a magnetic tunnel junction element and a magnetoresistive memory device. The magnetic tunnel junction element includes a fixed layer maintaining a magnetization direction, an insulating layer, a free layer having a variable magnetization direction, and an antiferromagnetic oxide layer. The fixed layer, the free layer, and the antiferromagnetic oxide layer may be sequentially stacked. The free layer and the antiferromagnetic oxide layer may be in direct contact with each other.

## Claims

### Claim 1

A magnetic tunnel junction element comprising:
a fixed layer maintaining a magnetization direction;
an insulating layer;
a free layer having a variable magnetization direction; and
an antiferromagnetic oxide layer in direct contact with the free layer, wherein
the fixed layer, the free layer, the insulating layer, and the antiferromagnetic oxide layer are sequentially stacked,
a thickness of the antiferromagnetic oxide layer is greater than or equal to about 0.5 nm and less than or equal to about 2 nm, and
wherein an electrical resistance of the antiferromagnetic oxide layer is less than an electrical resistance of the insulating layer.

### Claim 2 (depends on 1)

The magnetic tunnel junction element of claim 1,
wherein
a magnetic anisotropy of the free layer is in a direction perpendicular to a stack surface, and
the direction perpendicular to the stack surface extends from a lower surface to an upper surface of a stack structure including the fixed layer, the free layer, the insulating layer, and the antiferromagnetic oxide layer.

### Claim 3 (depends on 2)

The magnetic tunnel junction element of claim 2, wherein
a direction of a bias magnetic field generated from the antiferromagnetic oxide layer is parallel to the stack surface, and
a direction parallel to the stack surface is parallel to the lower surface of a stack structure.

### Claim 4 (depends on 1)

The magnetic tunnel junction element of claim 1, wherein
a thickness of the free layer is greater than or equal to about 0.6 nm and less than or equal to about 1 nm,
a magnetic anisotropy of the free layer is in a direction perpendicular to a stack surface, and
the direction perpendicular to the stack surface extends from a lower surface to an upper surface of a stack structure including the fixed layer, the free layer, the insulating layer, and the antiferromagnetic oxide layer.

### Claim 5 (depends on 1)

The magnetic tunnel junction element of claim 1, the antiferromagnetic oxide layer includes CoO, a mixture of NiO and CoO, NiO and VO, or a combination of MnO, CoO, and CuO.

### Claim 6 (depends on 1)

The magnetic tunnel junction element of claim 1, wherein
a thickness of the free layer is about 0.6 nm to about 1 nm.

### Claim 7 (depends on 1)

The magnetic tunnel junction element of claim 1, wherein
the fixed layer includes a first fixed layer and a second fixed layer on the first fixed layer,
the first fixed layer includes CoFeB as a main component,
the second fixed layer includes a Co/Pt multilayer film,
the second fixed layer is on the first fixed layer, and
the second fixed layer is between the first fixed layer and the insulating layer.

### Claim 8 (depends on 7)

The magnetic tunnel junction element of claim 7, wherein the insulating layer includes one of MgO, CaO, SrO, ViO, VO, NbO, or MgAl2O4.

### Claim 9 (depends on 7)

The magnetic tunnel junction element of claim 7, wherein
the first fixed layer further includes a Co-based full-Heusler alloy,
the free layer includes a Co-based full-Heusler alloy, a MnGaGe-based material, or a FeNi-based material.

### Claim 10

A magnetoresistive memory device comprising:
a magnetic tunnel junction element including a fixed layer maintaining a magnetization direction, an insulating layer, a free layer having a variable magnetization direction, and an antiferromagnetic oxide layer in direct contact with the free layer, wherein the fixed layer, the insulating layer, the free layer, and the antiferromagnetic oxide layer are sequentially stacked, a thickness of the antiferromagnetic oxide layer is greater than or equal to about 0.5 nm and less than or equal to about 2 nm; and
an electrode configured to apply a voltage to the magnetic tunnel junction element, wherein
an electrical resistance of the antiferromagnetic oxide layer is less than an electrical resistance of the insulating layer.

### Claim 11 (depends on 10)

The magnetoresistive memory device of claim 10, wherein
a magnetic anisotropy of the free layer is in a direction perpendicular to a stack surface, and
the direction perpendicular to the stack surface extends from a lower surface to an upper surface of a stack structure including the fixed layer, the free layer, the insulating layer, and the antiferromagnetic oxide layer.

### Claim 12 (depends on 11)

The magnetoresistive memory device of claim 11, wherein
a direction of a bias magnetic field generated from the antiferromagnetic oxide layer is parallel to the stack surface, and
a direction parallel to the stack surface is parallel to the lower surface of the stack structure.

### Claim 13 (depends on 10)

The magnetoresistive memory device of claim 10, wherein a thickness of the free layer is greater than or equal to about 0.6 nm and less than or equal to about 1 nm,
a magnetic anisotropy of the free layer is in a direction perpendicular to a stack surface, and
the direction perpendicular to the stack surface extends from a lower surface to an upper surface of a stack structure including the fixed layer, the free layer, the insulating layer, and the antiferromagnetic oxide layer.

### Claim 14 (depends on 13)

The magnetoresistive memory device of claim 13, wherein the antiferromagnetic oxide layer includes CoO, a mixture of NiO and CoO, NiO and VO, or a combination of MnO, CoO, and CuO.

### Claim 15 (depends on 10)

The magnetoresistive memory device of claim 10, wherein a thickness of the free layer is about 0.6 nm to about 1 nm.

### Claim 16 (depends on 10)

The magnetoresistive memory device of claim 10, wherein
the fixed layer includes a first fixed layer and a second fixed layer on the first fixed layer,
the first fixed layer includes CoFeB as a main component,
the second fixed layer includes a Co/Pt multilayer film,
the second fixed layer is on the first fixed layer, and
the second fixed layer is between the first fixed layer and the insulating layer.

### Claim 17 (depends on 10)

The magnetoresistive memory device of claim 10, wherein the insulating layer includes one of MgO, CaO, SrO, ViO, VO, NbO, or MgAl2O4.

### Claim 18 (depends on 10)

The magnetoresistive memory device of claim 10, wherein
the fixed layer further includes a Co-based full-Heusler alloy,
the free layer includes a Co-based full-Heusler alloy, a MnGaGe-based material, or a FeNi-based material.