Magnetic tunnel junction device and memory device including the same

• US 20100181632A1
• Filed: 03/23/2010
• Published: 07/22/2010
• Est. Priority Date: 03/12/2004
• Status: Abandoned Application

• Current Assignee: National Institute of Advanced Industrial Science and Technology (Government of Japan), Japan Science & Technology Trading Co. Limited
• Original Assignee: National Institute of Advanced Industrial Science and Technology (Government of Japan), Japan Science & Technology Trading Co. Limited
• Inventors: Yuasa, Shinji
• Application Number:
  US12/659,827
• Publication Number:
  US 20100181632A1
• 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 11/15 using multiple magnetic layers G11C11/155 takes precedence
• CPC Class Codes: G11C 11/16 using elements in which the storage effect is based on magnetic spin effect
• CPC Class Codes: G11C 11/161 details concerning the memory cell structure, e.g. the layers of the ferromagnetic memory cell
• CPC Class Codes: H01F 10/132 containing cobalt
• CPC Class Codes: H01F 10/3254 the spacer being semiconducting or insulating, e.g. for spin tunnel junction [STJ]
• CPC Class Codes: H01L 28/55 with a dielectric comprising a perovskite structure material
• CPC Class Codes: H10B 53/30 characterised by the memory core region
• CPC Class Codes: H10B 61/00 Magnetic memory devices, e.g. magnetoresistive RAM [MRAM] devices
• 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
• CPC Class Codes: H10N 59/00 Integrated devices, or assemblies of multiple devices, comprising at least one galvanomagnetic or Hall-effect element covered by groups H10N50/00 - H10N52/00 MRAM devices H10B61/00

Abstract

The output voltage of an MRAM is increased by means of an Fe(001)/MgO(001)/Fe(001) MTJ device, which is formed by microfabrication of a sample prepared by the following steps. A single-crystalline MgO (001) substrate 11 is prepared. An epitaxial Fe(001) lower electrode (a first electrode) 17 with the thickness of 50 nm is grown on a MgO(001) seed layer 15 at room temperature, followed by annealing under ultrahigh vacuum (2×10⁻⁸ Pa) and at 350° C. A MgO(001) barrier layer 21 with the thickness of 2 nm is epitaxially formed on the Fe(001) lower electrode (the first electrode) at room temperature, using a MgO electron-beam evaporation. A Fe(001) upper electrode (a second electrode) with the thickness of 10 nm is then formed on the MgO(001) barrier layer 21 at room temperature. This is successively followed by the deposition of a Co layer 21 with the thickness of 10 nm on the Fe(001) upper electrode (the second electrode) 23. The Co layer 21 is provided so as to increase the coercive force of the upper electrode 23 in order to realize an antiparallel magnetization alignment.

Claims

1. A method of manufacturing a magnetoresistive device comprising:

preparing a substrate;

depositing a first amorphous ferromagnetic material layer on said substrate;

forming an amorphous MgO or MgO_x (0<

x<

1) layer on said first amorphous ferromagnetic material layer and then crystallizing said amorphous MgO or MgO_x, (0<

x<

1) layer by annealing so as to form a tunnel barrier layer comprising a poly-crystalline MgO or MgO_x (0<

x<

1) layer in which (001) crystal plane is preferentially oriented; and

depositing a second amorphous ferromagnetic material layer on said tunnel barrier layer.

3. The method of manufacturing a magnetoresistive device according to claim 1, wherein

said ferromagnetic material layers comprises CoFeB alloy.

5. The method of manufacturing the magnetoresistive device according to claim 1, wherein the method further comprises an annealing step as to partially or entirely crystallize said amorphous ferromagnetic material layer or layers.

7. The method of manufacturing a magnetoresistive device according to claim 5, wherein

said amorphous ferromagnetic material layer comprises CoFeB alloy.

10. The method of manufacturing the magnetoresistive device according to claim 5, wherein the method further comprises an annealing step as to partially or entirely crystallize said amorphous ferromagnetic material layer or layers.

2. A method of manufacturing a magnetoresistive device comprising:

preparing a substrate;

depositing a first amorphous ferromagnetic material layer on said substrate;

forming an amorphous MgO or MgO_x, (0<

x<

1) layer on said first amorphous ferromagnetic material layer and then crystallizing said amorphous MgO or MgO_x (0<

x<

1) layer by annealing so as to form a tunnel barrier layer comprising a poly-crystalline MgO or MgO_x (0<

x<

1) layer in which (001) crystal plane is preferentially oriented; and

depositing a second ferromagnetic material layer on said tunnel barrier layer.

4. The method of manufacturing a magnetoresistive device according to claim 2, wherein

said amorphous ferromagnetic material layer comprises CoFeB alloy.

6. The method of manufacturing the magnetoresistive device according to claim 2, wherein the method further comprises an annealing step as to partially or entirely crystallize said amorphous ferromagnetic material layer or layers.

8. The method of manufacturing a magnetoresistive device according to claim 6, wherein

said amorphous ferromagnetic material layer comprises CoFeB alloy.

9. A method of manufacturing a magnetoresistive device comprising:

preparing a substrate;

depositing a first amorphous ferromagnetic material layer on said substrate;

forming an amorphous magnesium oxide layer on said first amorphous ferromagnetic material layer and then crystallizing said amorphous magnesium oxide layer by annealing so as to form a tunnel barrier layer comprising a poly-crystalline magnesium oxide in which (001) crystal plane is preferentially oriented; and

depositing a second amorphous ferromagnetic material layer on said tunnel barrier layer.

11. A magnetoresistive device having a magnetic tunnel junction structure comprising:

a first amorphous ferromagnetic material layer formed on a substrate;

a tunnel barrier layer on said first amorphous ferromagnetic material layer; and

a second ferromagnetic material layer formed on said tunnel barrier layer, wherein

said tunnel barrier layer comprises a poly-crystalline MgO_x (0<

x<

1) in which (001) crystal plane is preferentially oriented.

12. The magnetoresistive device according to claim 11, wherein said first and second amorphous ferromagnetic material layers comprise CoFeB alloy.

13. A magnetoresistive device having a magnetic tunnel junction structure comprising:

a tunnel barrier layer deposited on an amorphous ferromagnetic material layer, wherein

said tunnel barrier layer comprises a poly-crystalline MgO_x (0<

x<

1) in which (001) crystal plane is preferentially oriented.

14. The magnetoresistive device according to claim 13, wherein said first and second amorphous ferromagnetic material layers comprise CoFeB alloy.

15. A magnetoresistive device having a magnetic tunnel junction structure comprising:

a first amorphous ferromagnetic material layer formed on a substrate;

a tunnel barrier layer on said first amorphous ferromagnetic material layer; and

a second ferromagnetic material layer formed on said tunnel barrier layer, wherein

said tunnel barrier layer comprises a poly-crystalline MgO in which (001) crystal plane is preferentially oriented, and said MgO has oxygen vacancy defects.

16. The magnetoresistive device according to claim 15, wherein said first and second amorphous ferromagnetic material layers comprise CoFeB alloy.

17. A magnetoresistive device having a magnetic tunnel junction structure comprising:

a tunnel barrier layer deposited on an amorphous ferromagnetic material layer, wherein

said tunnel barrier layer comprises a poly-crystalline MgO in which (001) crystal plane is preferentially oriented, and said MgO has oxygen vacancy defects.

18. The magnetoresistive device according to claim 17, wherein said first and second amorphous ferromagnetic material layers comprise CoFeB alloy.

19. A magnetic multilayer film comprising:

a first amorphous ferromagnetic material layer formed on a substrate;

a tunnel barrier layer deposited on said first amorphous ferromagnetic material layer; and

a second ferromagnetic material layer deposited on said tunnel barrier layer, wherein

said tunnel barrier layer comprises a poly-crystalline magnesium oxide in which (001) crystal plane is preferentially oriented.

20. The magnetoresistive device according to claim 19, wherein said first amorphous ferromagnetic material layer comprises CoFeB alloy.