# US 11,910,725 B2 · Magnetic structure for magnetic device

> Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt

- Number: US 11,910,725 B2
- Document ID: US11910725B2
- Status: Granted
- Kind: B2
- Application number: 17/121,279
- Filed: 2020-12-14
- Published: 2021-07-08
- Granted: 2024-02-20
- Earliest claimed: 2019-12-18
- Assignees: Imec Vzw; Katholieke Universiteit Leuven
- Applicants: IMEC vzw; Katholieke Universiteit Leuven
- Inventors: Bart Vermeulen; Mihaela Ioana Popovici; Koen Martens; Gouri Sankar Kar
- Web page: https://patentgrep.com/patent/US11910725B2

## CPC

- H01F 10/3236: {made of a noble metal, e.g.(Co/Pt) n multilayers having perpendicular anisotropy (H01F10/3286 takes precedence)}
- H10N 50/85: Materials of the active region
- H01F 10/3286: {Spin-exchange coupled multilayers having at least one layer with perpendicular magnetic anisotropy}
- 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}
- H01F 41/302: {for applying spin-exchange-coupled multilayers, e.g. nanostructured superlattices (spin-exchange-coupled multilayers H01F10/32)}
- H10B 61/00: Magnetic memory devices, e.g. magnetoresistive RAM [MRAM] devices
- H10N 50/01: Manufacture or treatment
- H10N 50/10: Magnetoresistive devices
- H10N 50/80: Constructional details
- H01F 10/3254: {the spacer being semiconducting or insulating, e.g. for spin tunnel junction [STJ]}
- H01F: MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
- H10N: ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
- H10B: ELECTRONIC MEMORY DEVICES

## Abstract

The present disclosure relates to magnetic devices. In particular, the disclosure relates to magnetic memory and logic devices that employ the voltage control of magnetic anisotropy (VCMA) effect for magnetization switching. The present disclosure provides a method for manufacturing a magnetic structure for such a magnetic device. The method comprising the following steps: providing a bottom electrode layer, forming a SrTiO3 (STO) stack on the bottom electrode layer by atomic layer deposition (ALD) of at least two different STO nanolaminates, forming a magnetic layer on the STO stack, and forming a perpendicular magnetic anisotropy (PMA) promoting layer on the magnetic layer, the PMA promoting layer being configured to promote PMA in the magnetic layer.

## Claims

### Claim 1

A magnetic device, comprising:
a bottom electrode layer;
a strontium titanate (STO) stack on the bottom electrode layer;
a magnetic layer on the STO stack, the magnetic layer having a perpendicular magnetic anisotropy and comprising a free magnetic layer;
a tunnel barrier on the magnetic layer;
a magnetic reference layer on the tunnel barrier;
a top electrode layer on or over the tunnel barrier;
a field bias layer, that is disposed between the magnetic reference layer and the top electrode layer, or is embedded into the top electrode layer that is formed on the magnetic reference layer; and
at least one first pillar each comprising the magnetic reference layer, the field bias layer and the top electrode layer.

### Claim 2 (depends on 1)

A method of manufacturing the magnetic device of claim 1, the method comprising:
providing the bottom electrode layer;
forming the STO stack on the bottom electrode layer by atomic layer deposition (ALD) of at least two different STO nanolaminates;
forming the magnetic layer on the STO stack, the magnetic layer comprising the free magnetic layer;
forming the tunnel barrier on the magnetic layer;
forming the magnetic reference layer on the tunnel barrier;
forming the top electrode layer on or over the tunnel barrier;
forming a field bias layer, that is disposed between the magnetic reference layer and the top electrode layer, or is embedded into the top electrode layer that is formed on the magnetic reference layer; and
forming at least one first pillar each comprising the magnetic reference layer, the field bias layer and the top electrode layer.

### Claim 3 (depends on 2)

The method of claim 2, wherein the STO stack comprises a Sr-rich STO nanolaminate and a Ti-rich STO nanolaminate.

### Claim 4 (depends on 3)

The method of claim 3, wherein the Sr-rich STO nanolaminate comprises a (Sr-rich STO/TiO2)n nanolaminate, wherein n is 1-5.

### Claim 5 (depends on 3)

The method of claim 3, wherein the Ti-rich STO nanolaminate comprises Sr in a range of 35-45%.

### Claim 6 (depends on 2)

The method of claim 2, wherein the bottom electrode layer comprises a tensile TiN layer.

### Claim 7 (depends on 2)

The method of claim 2, wherein the magnetic layer comprises Co, Ni, Fe or an alloy thereof, and wherein the tunnel barrier comprises a MgO layer.

### Claim 8 (depends on 1)

The magnetic device of claim 1, wherein the each of the at least one first pillar further comprises the tunnel barrier.

### Claim 9 (depends on 1)

The magnetic device of claim 1, further comprising at least one second pillar each comprising a further electrode layer on the tunnel barrier or on the magnetic layer.

### Claim 10 (depends on 1)

The magnetic device of claim 1, wherein the magnetic device is a three-terminal or two-terminal voltage control of magnetic anisotropy (VCMA) device or is a three-terminal spin-transfer torque (STT) device.

### Claim 11 (depends on 1)

The magnetic device of claim 1, wherein the magnetic device is a three-terminal device comprising:
a first terminal connected to the top electrode layer of a first pillar, a second terminal connected to the top electrode layer of another first pillar, and a third terminal connected to the bottom electrode layer; or
a first terminal connected to the top electrode layer of a first pillar, a second terminal connected to the further electrode layer of a second pillar, and a third terminal connected to the bottom electrode layer; or
a first terminal connected to the top electrode layer, a second terminal connected to the magnetic layer; and a third terminal connected to the bottom electrode layer.

### Claim 12

A magnetic structure for a magnetic device, the magnetic structure comprising:
a bottom electrode layer;
a strontium titanate (STO) stack on the bottom electrode layer and comprising at least two different STO nanolaminates;
a magnetic layer provided on the STO stack and having a perpendicular magnetic anisotropy; and
a Pt layer or a MgO layer on the magnetic layer.

### Claim 13 (depends on 12)

The magnetic structure of claim 12, wherein the STO stack has a permittivity greater than 100 at room temperature.

### Claim 14 (depends on 12)

The magnetic structure of claim 12, wherein a grain size of the STO of the STO stack is less than 50 nm.

### Claim 15 (depends on 1)

The magnetic device of claim 1, wherein the tunnel barrier comprises a MgO layer.

### Claim 16 (depends on 15)

The magnetic device of claim 15, wherein the magnetic device comprises a ferromagnet/MgO bilayer on the magnetic layer, wherein the ferromagnet/MgO bilayer comprises the MgO layer.

### Claim 17 (depends on 16)

The magnetic device of claim 16, wherein the ferromagnet/MgO bilayer is selected from the group consisting of a Co/MgO bilayer, a Fe/MgO bilayer, a Ni/MgO bilayer, or a bilayer of a Co/Fe/Ni alloy and the MgO layer.

### Claim 18 (depends on 12)

The magnetic structure of claim 12, wherein the magnetic structure comprises a bilayer on the magnetic layer, wherein the bilayer is a Co/Pt bilayer comprising the Pt layer or a ferromagnet/MgO bilayer comprising the MgO layer.