Magnetoresistive stack and method of fabricating same

Patent metadata

Field	Value
Publication number	US-9947865-B2
Application number	US-201715400889-A
Country	US
Kind code	B2
Filing date	Jan 6, 2017
Priority date	Jun 10, 2011
Publication date	Apr 17, 2018
Grant date	Apr 17, 2018

Abstract

A magnetoresistive element (e.g., a spin-torque magnetoresistive memory element) includes a fixed magnetic layer, a free magnetic layer, having a high-iron alloy interface region located along a surface of the free magnetic layer, wherein the high-iron alloy interface region has at least 50% iron by atomic composition, and a first dielectric, disposed between the fixed magnetic layer and the free magnetic layer. The magnetoresistive element further includes a second dielectric, having a first surface that is in contact with the surface of the free magnetic layer, and an electrode, disposed between the second dielectric and a conductor. The electrode includes: (i) a non-ferromagnetic portion having a surface that is in contact with a second surface of the second dielectric, and (ii) a second portion having at least one ferromagnetic material disposed between the non-ferromagnetic portion of the electrode and the conductor.

First claim

What is claimed is:

1. A method of manufacturing a magnetoresistive stack on a substrate, the method comprising:
forming a first dielectric layer over the substrate;
forming a free magnetic layer over the first dielectric layer, wherein a first surface of the free magnetic layer is in contact with the first dielectric layer, wherein forming the free magnetic layer includes:
depositing a first layer of iron over the first dielectric layer,
after depositing the first layer of iron, depositing a first layer of a ferromagnetic material on the first layer of iron,
after depositing the first layer of ferromagnetic material, depositing a non-ferromagnetic transition metal on the first layer of ferromagnetic material,
after depositing the non-ferromagnetic transition metal, depositing a second layer of a ferromagnetic material on the non-ferromagnetic transition metal, and
after depositing the second layer of ferromagnetic material, depositing a second layer of iron over the second layer of a ferromagnetic material;

forming a second dielectric layer on a second surface of the free magnetic layer; and
annealing the free magnetic layer, wherein, after annealing, the non-ferromagnetic transition metal does not break direct exchange coupling between the first layer of a ferromagnetic material and the second layer of a ferromagnetic material.

2. The method of manufacturing of claim 1 , further including forming a high-iron alloy interface region at the second surface of the free magnetic layer by annealing the second layer of iron of the free magnetic layer, wherein the high-iron alloy interface region has at least 50% iron by atomic composition.

3. The method of manufacturing of claim 1 , wherein the second layer of iron is deposited on the second layer of the ferromagnetic material and the method further includes:
forming a first high-iron alloy interface region at the second surface of the free magnetic layer, wherein the first high-iron alloy interface region is in contact with the second dielectric layer and has at least 50% iron by atomic composition and includes materials from (i) the second layer of iron and (ii) the second layer of a ferromagnetic material.

4. The method of manufacturing of claim 3 , further including forming a second high-iron alloy interface region at the first surface of the free magnetic layer, wherein the first high-iron alloy interface region is in contact with the first dielectric layer and has at least 50% iron by atomic composition and includes materials from (i) the first layer of iron and (ii) the first layer of a ferromagnetic material.

5. The method of manufacturing of claim 1 , wherein depositing the second layer of iron includes depositing iron having a thickness in the range of 1.5 Angstroms to 3 Angstroms.

6. The method of manufacturing of claim 5 , wherein depositing the second layer of iron includes depositing pure iron, and the method of manufacturing further includes:
forming a high-iron alloy interface region at the second surface of the free magnetic layer from the second layer of iron wherein the high-iron alloy interface region is in contact with the second dielectric layer and includes at least 50% iron by atomic composition.

7. The method of manufacturing of claim 1 , wherein:
depositing the first and second layers of ferromagnetic material each include depositing cobalt and iron, and
depositing a non-ferromagnetic transition metal includes depositing tantalum, titanium, molybdenum, niobium, vanadium, zirconium, hafnium, chromium, manganese or tungsten.

8. The method of manufacturing of claim 1 , wherein:
depositing the first and second layers of ferromagnetic material each include depositing cobalt and iron, and
depositing a non-ferromagnetic transition metal includes depositing niobium, zirconium, tungsten or molybdenum.

9. A method of manufacturing a magnetoresistive stack on a substrate, the method comprising:
forming a first dielectric layer over the substrate;
forming a second dielectric layer over the substrate;
forming a free magnetic layer between the first and second dielectric layers, wherein a first surface of the free magnetic layer is in contact with the first dielectric layer and a second surface of the free magnetic layer is in contact with the second dielectric layer, wherein forming the free magnetic layer includes:
depositing a first layer of a ferromagnetic material over the first dielectric layer, wherein the first layer of ferromagnetic material is an alloy including cobalt and iron,
after depositing the first layer of a ferromagnetic material, depositing a non-ferromagnetic transition metal on the first layer of ferromagnetic material,
after depositing the non-ferromagnetic transition metal, depositing a second layer of a ferromagnetic material on the non-ferromagnetic transition metal, wherein the second layer of ferromagnetic material is an alloy including cobalt and iron, and
after depositing the second layer of a ferromagnetic material, forming a high-iron alloy interface region on or over the second layer of the ferromagnetic material and at the second surface of the free magnetic layer, the high-iron alloy interface region includes at least 50% iron by atomic composition; and

annealing the free magnetic layer, wherein, after annealing, the non-ferromagnetic transition metal does not break direct exchange coupling between the first layer of a ferromagnetic material and the second layer of a ferromagnetic material.

10. The method of manufacturing of claim 9 , wherein forming the high-iron alloy interface region includes depositing a layer of iron on the second layer of the ferromagnetic material.

11. The method of manufacturing of claim 10 , wherein depositing the layer of iron includes depositing pure iron having a thickness in the range of 1.5 Angstroms to 3 Angstroms.

12. The method of manufacturing of claim 10 , wherein depositing the layer of iron includes depositing iron having a thickness that is less than 5 angstroms.

13. The method of manufacturing of claim 12 , wherein depositing a non-ferromagnetic transition metal includes depositing niobium, zirconium, tungsten or molybdenum.

14. The method of manufacturing of claim 9 , wherein depositing a non-ferromagnetic transition metal includes depositing tantalum, titanium, molybdenum, niobium, vanadium, zirconium, hafnium, chromium, manganese or tungsten.

15. The method of manufacturing of claim 9 , wherein depositing a non-ferromagnetic transition metal includes depositing niobium, zirconium, tungsten or molybdenum.

16. The method of manufacturing of claim 9 , wherein forming a high-iron alloy interface region on or over the second layer of the ferromagnetic material and at the second surface of the free magnetic layer further includes:
depositing a layer of iron on or over the second layer of the ferromagnetic material, and
annealing the layer of iron of the free magnetic layer to form a high-iron alloy including (i) at least 50% iron by atomic composition, (ii) at least one ferromagnetic material from the second layer of the ferromagnetic material, and (iii) iron from the layer of iron.

17. A method of manufacturing a magnetoresistive stack on a substrate, the method comprising:
forming a first dielectric layer over the substrate;
forming a second dielectric layer over the substrate; and
forming a free magnetic layer between the first and second dielectric layers, wherein a first surface of the free magnetic layer is in contact with the first dielectric layer and a second surface of the free magnetic layer is in contact w

Assignees

• Everspin Technologies Inc

Inventors

• Whig Renu
• Sun Jijun
• Rizzo Nicholas
• Slaughter Jon
• Houssameddine Dimitri
• Mancoff Frederick

Classifications

• G11C11/161 Primary

  details concerning the memory cell structure, e.g. the layers of the ferromagnetic memory cell · CPC title

• H01L43/02

  Electricity · mapped topic

• H01L43/12 Primary

  Electricity · mapped topic

• H01L43/10

  Electricity · mapped topic

• H01L43/08

  Electricity · mapped topic