Magnetic memory cell

• US 20080219042A1
• Filed: 03/07/2007
• Published: 09/11/2008
• Est. Priority Date: 03/07/2007
• Status: Active Grant

• Current Assignee: Headway Technologies Incorporated
• Original Assignee: Headway Technologies Incorporated
• Inventors: Zhang, Kunliang, Li, Min, Wang, Hui-Chuan, Zhao, Tong
• Granted Patent: US 8,335,105 B2
• Time in Patent Office: Days
• US Class Current: 365/158
• CPC Class Codes: G11C 11/15 using multiple magnetic layers G11C11/155 takes precedence

Abstract

By inserting a spin polarizing layer (typically pure iron) within the free layer of a MTJ or GMR memory cell, dR/R can be improved without significantly affecting other free layer properties such as Hc. Additional performance improvements can be achieved by also inserting a surfactant layer (typically oxygen) within the free layer.

Claims

1. A method to increase magneto-resistance of a magnetically free layer, comprising:

providing a magnetic memory cell comprising a pinned layer on a pinning layer, a transition layer on said pinned layer, and said free layer on said transition layer, said free layer further comprising at least one layer containing cobalt and iron and at least one layer containing nickel and iron; and

inserting within said free layer a spin polarizing layer, thereby improving performance of said free layer.

2. The method of claim 1 wherein said spin polarizing layer is selected from the group consisting of iron and FeB.

3. The method of claim 1 wherein said spin polarizing layer is deposited to a thickness between about 2 and 10 Angstroms.

4. The method of claim 1 wherein said magnetic memory cell is a TMR device or a GMR device.

5. A process for forming, as part of a magnetic memory cell, that has a dR/R value, a free layer having a coercivity, an anisotropy field, and a magnetostriction coefficient, comprising:

depositing a magnetic pinning layer on a substrate;

depositing a magnetically pinned layer on said pinning layer;

depositing a transition layer on said pinned layer;

depositing, on said transition layer, a first ferromagnetic layer;

depositing, on said first ferromagnetic layer, a layer of pure iron; and

depositing, on said pure iron layer, a second ferromagnetic layer whereby said free layer, comprising said iron layer sandwiched between said first and second ferromagnetic layers, is formed.

6. The process of claim 5 wherein the step of depositing a first ferromagnetic layer further comprises depositing a single layer of cobalt iron.

7. The process of claim 5 wherein the step of depositing a second ferromagnetic layer further comprises depositing a single layer of nickel iron.

8. The process of claim 5 wherein insertion of said layer of pure iron changes the free layer coercivity by less than 10%.

9. The process of claim 5 wherein the step of inserting said layer of pure iron changes the free layer anisotropy field by less than 10%.

10. The process of claim 5 wherein the step of inserting said layer of pure iron changes the free layer magnetostriction coefficient by less than 10%.

11. The process of claim 5 wherein the step of inserting said layer of pure iron increases the dR/R value of the magnetic memory cell by at least 20%.

12. A method to increase magneto-resistance of a magnetically free layer, comprising:

providing a magnetic memory cell comprising a pinned layer on a pinning layer, a transition layer on said pinned layer, and said free layer on said transition layer, said free layer further comprising at least one layer containing cobalt and iron, at least one layer containing nickel and iron, and at least one layer containing three or more elements selected from the group consisting of nickel, cobalt, iron, and boron;

inserting a spin polarizing layer between any two layers of said free layer; and

inserting a surfactant layer between any two layers of said free layer.

13. The method of claim 12 wherein said spin polarizing layer is selected from the group consisting of iron and FeB.

14. The method of claim 12 wherein said surfactant layer is selected from the group consisting of O₂, O₂ mixed with Ar, O₂ mixed with Kr, O₂ mixed with Xe, and O₂ mixed with Ne.

15. The method of claim 12 wherein said transition layer is copper and said magnetic memory cell is a GMR device selected from the group consisting of CIP, CPP, and CCP devices.

16. The method of claim 12 wherein said transition layer is a tunnel barrier layer whereby said magnetic memory cell is a TMR device.

17. A magnetically free layer in a magnetic memory cell comprising:

a pinned layer on a pinning layer;

a transition layer on said pinned layer;

on said transition layer, a layer of cobalt iron and a layer of nickel iron; and

a spin polarizing layer between said layers of cobalt iron and nickel iron.

18. The free layer described in claim 17 wherein said spin polarizing layer is selected from the group consisting of iron and FeB.

19. The free layer described in claim 17 wherein said transition layer is copper and said magnetic memory cell is a GMR device selected from the group consisting of CIP, CPP, and CCP devices.

20. The free layer described in claim 17 wherein said transition layer is a tunnel barrier layer whereby said magnetic memory cell is a TMR device having a dR/R ratio of at least 10%.

21. A magnetically free layer in a magnetic memory cell comprising:

a pinned layer on a pinning layer;

a transition layer on said pinned layer;

on said transition layer, at least one layer containing cobalt iron, at least one layer containing nickel iron, and at least one layer containing three or more elements selected from the group consisting of nickel, cobalt, iron, and boron [ANY OTHERS?];

a spin polarizing layer between any two layers of said free layer; and

a surfactant layer between any two layers of said free layer.

22. The free layer described in claim 21 wherein said spin polarizing layer is selected from the group consisting of iron and FeB.

23. The free layer described in claim 21 wherein said surfactant layer is selected from the group consisting of O₂, O₂ mixed with Ar, O₂ mixed with Kr, O₂ mixed with Xe, and O₂ mixed with Ne.

24. The free layer described in claim 21 wherein said transition layer is a tunnel barrier layer whereby said magnetic memory cell is a TMR device having a dR/R value of at least 10%.

25. The free layer described in claim 21 wherein said transition layer is copper and said magnetic memory cell is a GMR device selected from the group consisting of CIP, CPP, and CCP devices.