MAGNETIC TUNNEL JUNCTION COMPRISING A POLARIZING LAYER

• US 20120181642A1
• Filed: 01/12/2012
• Published: 07/19/2012
• Est. Priority Date: 01/13/2011
• Status: Active Grant

• Current Assignee: Allegro Microsystems Incorporated (Sanken Electric Company Limited)
• Original Assignee: Crocus Technology S.A.
• Inventors: Prejbeanu, Ioan Lucian, Sousa, Ricardo
• Granted Patent: US 8,609,439 B2
• Time in Patent Office: Days
• US Class Current: 257/421
• CPC Class Codes: B82Y 10/00 Nanotechnology for information processing, storage or transmission, e.g. quantum computing or single electron logic
• CPC Class Codes: B82Y 25/00 Nanomagnetism, e.g. magnetoimpedance, anisotropic magnetoresistance, giant magnetoresistance or tunneling magnetoresistance
• 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 11/1675 Writing or programming circuits or methods
• CPC Class Codes: H01F 10/3254 the spacer being semiconducting or insulating, e.g. for spin tunnel junction [STJ]
• 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: H10B 61/22 of the field-effect transistor [FET] type
• CPC Class Codes: H10N 50/10 Magnetoresistive devices

Abstract

The present disclosure concerns memory device comprising magnetic tunnel junction comprising a tunnel barrier layer between a first ferromagnetic layer having a first magnetization with a fixed orientation and a second ferromagnetic layer having a second magnetization being freely orientable, and a polarizing layer having a polarizing magnetization substantially perpendicular to the first and second magnetization; the first and second ferromagnetic layers being annealed such that a tunnel magnetoresistance of the magnetic tunnel junction is equal or greater than about 150%. Also disclosed is a method of forming the MRAM cell.

Claims

1. A method for manufacturing a magnetic tunnel junction to be written with a spin polarized current, the magnetic tunnel junction comprising a tunnel barrier layer between a first ferromagnetic layer having a first magnetization with a fixed orientation and a second ferromagnetic layer having a second magnetization being freely orientable, and a polarizing layer having a polarizing magnetization;

comprising;

depositing the first ferromagnetic layer, the tunnel barrier layer, and the second ferromagnetic layer;

annealing the deposited ferromagnetic layers at a first annealing temperature such as a tunnel magnetoresistance of the magnetic tunnel junction is equal or greater than about 150%;

depositing the polarizer layer; and

annealing the deposited polarizer layer at a second annealing temperature such as to orient the polarizing magnetization substantially perpendicular to the first and second magnetization, said annealing the deposited ferromagnetic layers at the first annealing temperature being performed prior to depositing the polarizer layer.

2. The method according to claim 1, wherein the second annealing temperature is lower that the first annealing temperature.

3. The method according to claim 1, wherein the first annealing temperature is comprised between about 340°

C. and 360°

C.

4. The method according to claim 1, wherein the second predetermined annealing temperature is comprised between about 150°

C. and 250°

C.

5. The method according to claim 1, wherein depositing the second ferromagnetic layer, the tunnel barrier layer, and the first ferromagnetic layer, is performed in this order.

6. The method according to claim 1, wherein depositing the first ferromagnetic layer, the tunnel barrier layer, and the second ferromagnetic layer is performed in this order.

7. A MRAM cell comprising a magnetic tunnel junction comprising a tunnel barrier layer between a first ferromagnetic layer having a first magnetization with a fixed orientation and a second ferromagnetic layer having a second magnetization being freely orientable, and a polarizing layer having a polarizing magnetization substantially perpendicular to the first and second magnetization;

the first and second ferromagnetic layers being annealed such that a tunnel magnetoresistance of the magnetic tunnel junction is equal or greater than about 150%.

8. A magnetic memory device comprising a plurality of MRAM cells, each MRAM cell comprising a magnetic tunnel junction comprising a tunnel barrier layer between a first ferromagnetic layer having a first magnetization with a fixed orientation and a second ferromagnetic layer having a second magnetization being freely orientable, and a polarizing layer having a polarizing magnetization substantially perpendicular to the first and second magnetization;

the first and second ferromagnetic layers being such that a tunnel magnetoresistance of the magnetic tunnel junction is equal or greater than about 150%.