Magnetoresistive device and method for manufacturing same

• US 20050219769A1
• Filed: 09/19/2003
• Published: 10/06/2005
• Est. Priority Date: 09/27/2002
• Status: Active Grant

• Current Assignee: NEC Corporation
• Original Assignee: NEC Corporation
• Inventors: Mori, Kaoru, Fukumoto, Yoshiyuki, Kamijo, Atsushi, Shimura, Ken-ichi
• Granted Patent: US 7,187,525 B2
• Time in Patent Office: Days
• US Class Current: 360/324.200
• 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: G11B 5/3909 Arrangements using a magnetic tunnel junction
• CPC Class Codes: H01F 10/3254 the spacer being semiconducting or insulating, e.g. for spin tunnel junction [STJ]
• CPC Class Codes: H10N 50/01 Manufacture or treatment
• CPC Class Codes: H10N 50/10 Magnetoresistive devices

Abstract

The heat resistance of a magnetic resistance device utilizing the TMR effect is improved. Also, the Neel effect of the magnetic resistance device utilizing the TMR effect is restrained. The magnetic resistance device includes a first ferromagnetic layer formed of ferromagnetic material, a non-magnetic insulative tunnel barrier layer coupled to the first ferromagnetic layer, a second ferromagnetic layer formed of ferromagnetic material and coupled to the tunnel barrier layer, and an anti-ferromagnetic layer formed of anti-ferromagnetic material. The second ferromagnetic layer is provided between the tunnel barrier layer and the anti-ferromagnetic layer. A perpendicular line from an optional position of the surface of the second ferromagnetic layer passes through at least two of the crystal grains of the second ferromagnetic layer.

Claims

1. A magnetic resistance device comprising:

a first ferromagnetic layer formed of ferromagnetic material;

a non-magnetic insulative tunnel barrier layer coupled to said first ferromagnetic layer;

a second ferromagnetic layer coupled to said tunnel barrier layer and formed of ferromagnetic material; and

an anti-ferromagnetic layer formed of anti-ferromagnetic material,

wherein said second ferromagnetic layer is provided between said tunnel barrier layer and said anti-ferromagnetic layer, and

at least a part of said second ferromagnetic layer is formed such that a line perpendicular to a surface of said second ferromagnetic layer on a side of said anti-ferromagnetic layer passes through at least two of crystal grains of said second ferromagnetic layer.

2. The magnetic resistance device according to claim 1, further comprising a substrate,

wherein said first ferromagnetic layer, said tunnel barrier layer, said second ferromagnetic layer and said anti-ferromagnetic layer are formed above a surface of said substrate, and

said tunnel barrier layer is formed on a side opposite to said substrate with respect to said second ferromagnetic layer.

3. The magnetic resistance device according to claim 1, further comprising:

a non-magnetic layer; and

a third ferromagnetic layer formed of ferromagnetic material,

wherein said third ferromagnetic layer is formed on said anti-ferromagnetic layer,

said non-magnetic layer is formed on said third ferromagnetic layer,

said second ferromagnetic layer is formed on said non-magnetic layer, and

said non-magnetic layer has a function to miniature said crystal grains in said second ferromagnetic layer when said second ferromagnetic layer is formed.

4. The magnetic resistance device according to claim 3, wherein said non-magnetic layer and said second ferromagnetic layer are formed of materials which belong to different point groups.

5. The magnetic resistance device according to claim 1, further comprising:

a non-magnetic layer coupled to said second ferromagnetic layer; and

a third ferromagnetic layer formed of ferromagnetic material and coupled to said non-magnetic layer,

wherein said second ferromagnetic layer, said non-magnetic layer and said third ferromagnetic layer are provided between said tunnel barrier layer and said anti-ferromagnetic layer, and

said non-magnetic layer is formed of an element selected from a group consisting of Ta, Al, Mg, Ti, Mo and W or an alloy of a plurality of elements selected from the group.

6. The magnetic resistance device according to claim 5, wherein said third ferromagnetic layer is formed on said anti-ferromagnetic layer,

said non-magnetic layer is formed on said third ferromagnetic layer, and

said second ferromagnetic layer is formed on said non-magnetic layer.

7. The magnetic resistance device according to claim 1, wherein an average grain diameter of grains in said second ferromagnetic layer is equal to or less than ⅔

of a film thickness of said second ferromagnetic layer.

8. The magnetic resistance device according to claim 7, wherein said average grain diameter of said grains in said second ferromagnetic layer is equal to or less than ½

of the film thickness of said second ferromagnetic layer.

9. The magnetic resistance device according to claim 1, wherein said anti-ferromagnetic layer contains Mn.

10. A magnetic resistance device comprising:

a first ferromagnetic layer formed of ferromagnetic material;

a non-magnetic insulative tunnel barrier layer coupled to said first ferromagnetic layer;

a second ferromagnetic layer formed of ferromagnetic material and coupled to said tunnel barrier layer; and

an anti-ferromagnetic layer formed of anti-ferromagnetic material containing Mn,

wherein said second ferromagnetic layer is provided between said tunnel barrier layer and said anti-ferromagnetic layer, and

crystal grains in said second ferromagnetic layer are arranged to prevent diffusion of said Mn from said anti-ferromagnetic layer to said tunnel barrier layer.

11. A method of manufacturing a magnetic resistance device comprising:

(A) forming an anti-ferromagnetic layer on a surface of a substrate in a vacuum chamber;

(B) introducing an oxidizing gas into said vacuum chamber after forming of said anti-ferromagnetic layer;

(C) exhausting said oxidizing gas from said vacuum chamber;

(D) forming a pinned ferromagnetic layer on said anti-ferromagnetic layer after said oxidizing gas is exhausted;

(E) forming a tunnel barrier layer on said first ferromagnetic layer; and

(F) forming a second ferromagnetic layer on said tunnel barrier layer.

12. The method of manufacturing a magnetic resistance device according to claim 11, wherein said oxidizing gas is an oxygen gas, and

a partial pressure of said oxidizing gas is larger than 0 and is smaller than 1×

10−

4 Pa, when said oxidizing gas is introduced in said (B) step.

13. A method of manufacturing a magnetic resistance device comprising:

(G) forming an anti-ferromagnetic layer on a surface of a substrate;

(H) forming a pinned ferromagnetic layer on said anti-ferromagnetic layer in an atmosphere containing an oxidizing gas;

(I) forming a tunnel barrier layer on said pinned ferromagnetic layer; and

(J) forming a free ferromagnetic layer on said tunnel barrier layer,

wherein a partial pressure of said oxidizing gas during said (H) process is determined such that said first ferromagnetic layer indicates electric conductivity.

14. The method of manufacturing magnetic a resistance element according to claim 13, wherein said oxidizing gas is an oxygen gas, and

said partial pressure of said oxidizing gas during said (H) process is larger than 0 and is smaller than 5×

10<sup>−

5</sup> Pa.