MAGNETIC TUNNEL JUNCTION STRUCTURES AND RELATED METHODS

• US 20200136016A1
• Filed: 06/03/2019
• Published: 04/30/2020
• Est. Priority Date: 10/30/2018
• Status: Active Grant

• Current Assignee: Taiwan Semiconductor Manufacturing Company Limited
• Original Assignee: Taiwan Semiconductor Manufacturing Company Limited
• Inventors: LIN, Shy-Jay, SONG, Mingyuan
• Granted Patent: US 11,107,975 B2
• Time in Patent Office: Days
• CPC Class Codes: G11C 11/161 details concerning the memory cell structure, e.g. the layers of the ferromagnetic memory cell
• CPC Class Codes: G11C 11/18 using Hall-effect devices
• CPC Class Codes: H01F 10/3259 Spin-exchange-coupled multilayers comprising at least a nanooxide layer [NOL], e.g. with a NOL spacer
• CPC Class Codes: H01F 10/3286 Spin-exchange coupled multilayers having at least one layer with perpendicular magnetic anisotropy
• CPC Class Codes: 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
• CPC Class Codes: H01F 41/307 insulating or semiconductive spacer
• CPC Class Codes: H10B 61/22 of the field-effect transistor [FET] type
• CPC Class Codes: H10N 50/01 Manufacture or treatment
• CPC Class Codes: H10N 50/10 Magnetoresistive devices
• CPC Class Codes: H10N 50/80 Constructional details
• CPC Class Codes: H10N 50/85 Magnetic active materials

Abstract

The disclosure is directed to spin-orbit torque (“SOT”) magnetoresistive random-access memory (“MRAM”) (“SOT-MRAM”) structures and methods. A SOT channel of the SOT-MRAM includes multiple heavy metal layers and one or more dielectric dusting layers each sandwiched between two adjacent heavy metal layers. The dielectric dusting layers each include discrete molecules or discrete molecule clusters of a dielectric material scattered in or adjacent to an interface between two adjacent heavy metal layers.

Claims

1. A method, comprising:

forming a first heavy metal layer over a substrate;

depositing a dielectric material over the first heavy metal layer;

forming a second heavy metal layer over the dielectric material and the first heavy metal layer; and

diffusing elements of the dielectric material into one or more of the first heavy metal layer or the second heavy metal layer.

2. The method of claim 1, wherein the depositing the dielectric material forms a plurality of molecules of the dielectric material randomly distributed in-plane on a surface of the first heavy metal layer.

3. The method of claim 1, further comprising forming a magnetic tunnel junction structure adjacent to one of the first heavy metal layer or the second heavy metal layer.

4. The method of claim 1, wherein the first heavy metal layer and the second heavy metal layer are each thinner than about 10 Å

.

5. The method of claim 1, wherein the average thickness of the deposited dielectric material is less than about 1 Å

.

6. The method of claim 1, wherein the first heavy metal layer is one or more of tungsten, platinum, or tantalum.

7. The method of claim 1, wherein the dielectric material is one or more of magnesium oxide, silicon dioxide or iron (III) oxide.

8. A structure, comprising:

a magnetic tunnel junction structure including a reference layer, a free layer and a tunneling barrier layer sandwiched between the reference layer and the free layer; and

a spin-orbit torque layer adjacent to the free layer of the magnetic tunnel junction structure, the spin-orbit torque layer including a first heavy metal layer, a second heavy metal layer and a first dielectric layer sandwiched between the first heavy metal layer and the second heavy metal layer.

9. The structure of claim 8, wherein the first dielectric layer of the spin-orbit torque layer includes discrete molecules of a dielectric material that are randomly distributed in-plane in an interface between the first heavy metal layer and the second heavy metal layer.

10. The structure of claim 9, wherein the first dielectric layer of the spin-orbit torque layer includes discrete molecules of the dielectric material that are positioned within one or more of the first heavy metal layer or the second heavy metal layer adjacent to the interface between the first heavy metal layer and are covered by the second heavy metal layer.

11. The structure of claim 8, wherein the spin-orbit torque layer further includes a third heavy metal layer and a second dielectric layer sandwiched between the second heavy metal layer and the third heavy metal layer.

12. The structure of claim 11, wherein the first dielectric layer includes individual molecules of a dielectric material randomly distributed in-plane in an interface between the first heavy metal layer and the second heavy metal layer, and the second dielectric layer includes individual molecules of the dielectric material randomly distributed in-plane in an interface between the second heavy metal layer and the third heavy metal layer, a lateral distance between a first molecule of the first dielectric layer and a second molecule of the first dielectric layer that is laterally adjacent to the first molecule being larger than a vertical distance between the first molecule of the first dielectric layer and a third molecule of the second dielectric layer that is vertically adjacent to the first molecule.

13. The structure of claim 8, wherein the spin-orbit torque layer fully overlaps the free layer of the magnetic tunnel junction structure.

14. A memory device, comprising:

a substrate;

a transistor over the substrate, the transistor having a first source/drain terminal, a second source/drain terminal and a gate terminal;

a magnetoresistive random access memory cell over the transistor, the magnetoresistive random access memory cell including a magnetic tunnel junction structure and a spin-orbit torque structure adjacent to the magnetic tunnel junction structure;

a write signal line coupled to the gate terminal;

a first current node coupled to the first source/drain terminal;

a first end of the spin-orbit torque structure coupled to the second source/drain terminal; and

a second end of the spin-orbit torque structure coupled to a second current node,

wherein the spin-orbit torque structure includes a first heavy metal layer, a second heavy metal layer stacked over the first heavy metal layer, and a first plurality of molecules of a dielectric material scattered adjacent to an interface between the first heavy metal layer and the second heavy metal layer.

15. The memory device of claim 14, wherein the first plurality of molecules are positioned randomly in-plane on a surface of the first heavy metal layer and are covered by the second heavy metal layer.

16. The memory device of claim 14, wherein the first plurality of molecules are discrete from one another and are positioned on the interface between the first heavy metal layer and the second heavy metal layer.

17. The memory device of claim 14, wherein the first plurality of molecules are diffused into one or more of the first heavy metal layer or the second heavy metal layer and adjacent to the interface between the first heavy metal layer and the second heavy metal layer.

18. The memory device of claim 14, wherein the spin-orbit torque structure further includes a second plurality of discrete molecules of the dielectric material that are substantially randomly distributed within one or more of the first heavy metal layer or the second heavy metal layer adjacent to the interface between the first heavy metal layer and the second heavy metal layer.

19. The memory device of claim 14, wherein the magnetic tunnel junction includes a first ferromagnetic layer of a fixed magnetization orientation, a second ferromagnetic layer of a variable magnetization orientation, and a dielectric tunnel barrier layer sandwiched between the first ferromagnetic layer and the second ferromagnetic layer.

20. The memory device of claim 14, wherein the first heavy metal layer and the second heavy metal layer are one or more of tungsten, platinum or tantalum.