Magnetic storage device

Abstract

This invention provides a magnetic storage device comprising a magnetoresistive element with excellent properties. The magnetic storage device of the embodiment includes a first electrode, a second electrode, and a magnetoresistive element. The magnetoresistive element includes a first magnetic layer, a second magnetic layer, an insulating layer disposed between the first and second magnetic layers, and a lanthanide oxide layer disposed between the first electrode and the first magnetic layer. The lanthanide oxide layer contains at least one lanthanide element selected from La, Ce, Pr, Nd, Pm, Sm, Eu, Tb, Dy, Ho, Er, Tm, Yb, and Lu, oxygen, and at least one specified element selected from Ru, Rh, Pd, Re, Os, and Pt. The lanthanide oxide layer comprises a first portion and a second portion respectively containing at least one lanthanide element and oxygen, wherein the concentration of the at least one specified element is higher in the first portion than in the second portion, and the second portion is located between the first portion and the first magnetic layer.

Description

Technical Field

[0001] Embodiments of the present invention relate to a magnetic storage device. Background Technology

[0002] A magnetic storage device integrating multiple magnetoresistive elements on a semiconductor substrate is proposed. Summary of the Invention

[0003] The present invention provides a magnetic storage device comprising a magnetoresistive element having excellent properties.

[0004] The magnetic storage device of the embodiment is a magnetic storage device comprising a first electrode, a second electrode, and a magnetoresistive element disposed between the first electrode and the second electrode. The magnetoresistive element includes a first magnetic layer, a second magnetic layer, an insulating layer disposed between the first magnetic layer and the second magnetic layer, and a lanthanide oxide layer disposed between the first electrode and the first magnetic layer. The lanthanide oxide layer contains elements selected from lanthanum (La), cerium (Ce), praseodymium (Pr), neodymium (Nd), promethium (Pm), samarium (Sm), europium (Eu), and terbium (Tb). The lanthanide oxide layer comprises at least one lanthanide element selected from dysprosium (Dy), holmium (Ho), erbium (Er), thulium (Tm), ytterbium (Yb), and lutetium (Lu), oxygen (O), and at least one specified element selected from ruthenium (Ru), rhodium (Rh), palladium (Pd), rhenium (Re), osmium (Os), and platinum (Pt). The lanthanide oxide layer comprises a first portion and a second portion respectively containing the at least one lanthanide element and oxygen (O), wherein the concentration of the at least one specified element is higher in the first portion than in the second portion, and the second portion is located between the first portion and the first magnetic layer. Attached Figure Description

[0005] Figure 1 This is a cross-sectional view schematically showing the configuration of the magnetic storage device according to the first embodiment.

[0006] Figure 2 This is a cross-sectional view schematically showing a first configuration example of the magnetic storage device according to the first embodiment.

[0007] Figure 3 This is a cross-sectional view schematically showing a second configuration example of the magnetic storage device of the first embodiment.

[0008] Figure 4 This is a cross-sectional view schematically illustrating a part of the manufacturing method of a second configuration example of the magnetic storage device of the first embodiment.

[0009] Figure 5 This is a cross-sectional view schematically showing a third configuration example of the magnetic storage device of the first embodiment.

[0010] Figure 6 This is a cross-sectional view schematically illustrating a part of the manufacturing method of a third configuration example of the magnetic storage device of the first embodiment.

[0011] Figure 7 This is a cross-sectional view schematically showing the configuration of the magnetic storage device according to the second embodiment.

[0012] Figure 8 This is a cross-sectional view schematically showing a first configuration example of the magnetic storage device according to the second embodiment.

[0013] Figure 9 This is a cross-sectional view schematically showing a second configuration example of the magnetic storage device according to the second embodiment.

[0014] Figure 10 This is a cross-sectional view schematically illustrating a third configuration example of the magnetic storage device of the second embodiment. Detailed Implementation

[0015] The embodiments will now be described with reference to the accompanying drawings.

[0016] (First Embodiment)

[0017] Figure 1 This is a cross-sectional view schematically showing the configuration of the magnetic storage device according to the first embodiment.

[0018] Figure 1 The magnetic storage device shown includes a first electrode 10, a second electrode 20, and a magnetoresistive element 30 disposed between the first electrode 10 and the second electrode 20. In this embodiment, the first electrode 10 functions as the upper electrode of the magnetoresistive element 30, and the second electrode 20 functions as the lower electrode of the magnetoresistive element 30.

[0019] The magnetoresistive effect element 30 is a vertically magnetized STT (spin transfer torque) type MTJ (magnetic tunnel junction) element, which includes a storage layer (first magnetic layer) 40, a reference layer (second magnetic layer) 50, a tunnel barrier layer (insulating layer) 60 and a lanthanide oxide layer 70, and has a structure in which these layers 40 to 70 are stacked between the first electrode 10 and the second electrode 20.

[0020] The first electrode 10 contains, for example, at least one element selected from tungsten (W), tantalum (Ta), tantalum nitride (TaN), titanium (Ti), titanium nitride (TiN), ruthenium (Ru), molybdenum (Mo), and hafnium (Hf).

[0021] The second electrode 20 contains, for example, at least one element selected from zirconium (Zr), hafnium (Hf), tungsten (W), chromium (Cr), molybdenum (Mo), niobium (Nb), titanium (Ti), tantalum (Ta), vanadium (V), ruthenium (Ru), and platinum (Pt).

[0022] The storage layer 40 is a ferromagnetic layer with a variable magnetization direction. The storage layer 40 contains at least one magnetic element, and may also contain boron (B). Specifically, the storage layer 40 contains at least one element selected from iron (Fe), cobalt (Co), and nickel (Ni), and may also contain boron (B). For example, the storage layer 40 may also be formed from a CoFeB layer containing Fe, Co, and B.

[0023] The reference layer 50 is a ferromagnetic layer with a fixed magnetization direction. The reference layer 50 contains at least one magnetic element, and may also contain boron (B). Specifically, the reference layer 50 contains at least one element selected from iron (Fe), cobalt (Co), and nickel (Ni), and may also contain boron (B). For example, the reference layer 50 may also be formed from a CoFeB layer containing Fe, Co, and B. In addition to layers containing magnetic elements and boron (B), the reference layer 50 may also contain superlattice layers of cobalt (Co) and platinum (Pt).

[0024] Furthermore, a variable magnetization direction refers to a magnetization direction that changes relative to a specified write current. Conversely, a fixed magnetization direction refers to a magnetization direction that remains constant relative to a specified write current.

[0025] The tunnel barrier layer 60 is an insulating layer disposed between the storage layer 40 and the reference layer 50, for example, formed of an MgO layer containing magnesium (Mg) and oxygen (O).

[0026] When the magnetization direction of the storage layer 40 is parallel to the magnetization direction of the reference layer 50, the magnetoresistive element 30 is in a low-resistance state; when the magnetization direction of the storage layer 40 is antiparallel to the magnetization direction of the reference layer 50, the magnetoresistive element 30 is in a high-resistance state. Therefore, the magnetoresistive element 30 can store binary data according to its resistance state.

[0027] A lanthanide oxide layer 70 is disposed between the first electrode 10 and the storage layer 40. In this embodiment, the lanthanide oxide layer 70 is disposed on the upper side of the storage layer 40, and the first electrode 10 is disposed on the upper side of the lanthanide oxide layer 70. The lanthanide oxide layer 70 functions as a capping layer.

[0028] The lanthanide oxide layer 70 contains at least one lanthanide element selected from lanthanum (La), cerium (Ce), praseodymium (Pr), neodymium (Nd), promethium (Pm), samarium (Sm), europium (Eu), terbium (Tb), dysprosium (Dy), holmium (Ho), erbium (Er), thulium (Tm), ytterbium (Yb) and lutetium (Lu), oxygen (O), and at least one specified element (at least one additive element) selected from ruthenium (Ru), rhodium (Rh), palladium (Pd), rhenium (Re), osmium (Os) and platinum (Pt).

[0029] For example, when at least one lanthanide element is represented as Ln and at least one specified element is represented as X, the lanthanide oxide layer 70 is represented as Ln. 2-a X a O3 layer (0 < a < 2). However, as described below, the value of "a" is not fixed within the lanthanide oxide layer 70.

[0030] The lanthanide oxide layer 70 may also contain at least one element selected from iron (Fe), cobalt (Co), boron (B) and nickel (Ni).

[0031] The concentration of at least one specified element in the lanthanide oxide layer 70 is higher on the first electrode 10 side than on the storage layer 40 side. In other words, the concentration of at least one specified element in the lanthanide oxide layer 70 is higher in the vicinity of the first electrode 10 than in the vicinity of the storage layer 40. Specifically, preferably, the concentration of at least one specified element is substantially zero in the vicinity of the interface between the storage layer 40 and the lanthanide oxide layer 70. That is, preferably, the concentration of at least one specified element is zero or so low as to be negligible.

[0032] The average concentration of at least one specified element in the lanthanide oxide layer 70 is preferably in the range of 1 at% to 50 at%.

[0033] In addition, the thickness of the lanthanide oxide layer 70 is preferably in the range of 0.6 nm to 3.0 nm.

[0034] As described above, in this embodiment, a lanthanide oxide layer 70 containing at least one specified element is disposed between the first electrode 10 and the storage layer 40. With this configuration, as described below, a magnetic storage device incorporating a magnetoresistive element with excellent characteristics can be obtained.

[0035] Generally, memory layers are formed by crystallizing an amorphous memory layer containing magnetic elements and boron through heat treatment. Specifically, boron is diffused through heat treatment to crystallize the amorphous memory layer, thereby forming a crystalline memory layer.

[0036] In addition, because lanthanide oxides have large inter-lattice voids, by placing a lanthanide oxide layer adjacent to the amorphous storage layer, the lanthanide oxide layer can effectively absorb boron during crystallization using heat treatment.

[0037] However, lanthanide oxides are essentially insulators. Therefore, when the lanthanide oxide layer is thick, its resistivity increases, leading to a decrease in the tunnel magnetoresistance ratio (TMR). On the other hand, when the lanthanide oxide layer is thin, agglomeration occurs, making it impossible to obtain a suitable lanthanide oxide layer.

[0038] In this embodiment, by providing a lanthanide oxide layer 70 containing at least one specified element adjacent to the storage layer 40, the problems described above can be suppressed.

[0039] When a specified element selected from Ru, Rh, Pd, Re, Os, and Pt is added to a lanthanide oxide, an interstitial energy level is formed near the Fermi level EF due to the specified element. By allowing current to flow through this interstitial energy level, the resistance of the lanthanide oxide can be reduced.

[0040] Therefore, in this embodiment, by providing a lanthanide oxide layer 70 containing at least one specified element, a lanthanide oxide layer 70 with a certain thickness and a low resistance value can be formed between the first electrode 10 and the storage layer 40. This allows for the acquisition of a magnetoresistive element with excellent characteristics.

[0041] Furthermore, in this embodiment, the concentration of at least one specified element in the lanthanide oxide layer 70 is higher on the first electrode 10 side than on the storage layer 40 side. That is, the concentration of at least one specified element in the lanthanide oxide layer 70 decreases near the interface between the storage layer 40 and the lanthanide oxide layer 70.

[0042] When the concentration of a specified element is high near the interface between the storage layer 40 and the lanthanide oxide layer 70, the damping constant of the storage layer 40 may increase due to the energy level formed by the specified element. In this embodiment, since the concentration of at least one specified element is low near the interface between the storage layer 40 and the lanthanide oxide layer 70, the increase in the damping constant of the storage layer 40 can be suppressed.

[0043] Furthermore, preferably, at the interface between the storage layer 40 and the lanthanide oxide layer 70, magnetic elements such as iron (Fe) are well bonded to oxygen (O). When the concentration of a specified element is high near the interface between the storage layer 40 and the lanthanide oxide layer 70, the good bonding between the magnetic element and oxygen may be damaged by the specified element. In this embodiment, since the concentration of at least one specified element is low near the interface between the storage layer 40 and the lanthanide oxide layer 70, good bonding between the magnetic element and oxygen can be ensured.

[0044] Next, a specific configuration example of the magnetic storage device according to this embodiment will be described. Furthermore, in the following configuration example, only the first electrode 10, the storage layer 40, and the lanthanide oxide layer 70 are shown; however, a layer is provided on the lower side of the storage layer 40. Figure 1 The tunnel barrier layer 60, reference layer 50, and second electrode 20 are shown.

[0045] Figure 2 This is a cross-sectional view schematically showing the first configuration example of this embodiment.

[0046] In this configuration example, the lanthanide oxide layer 70 includes a first layer portion 70a and a second layer portion 70b disposed between the storage layer 40 and the first layer portion 70a.

[0047] The first layer portion 70a is formed of a lanthanide oxide containing at least one lanthanide element, oxygen (O) and at least one specified element.

[0048] The second layer portion 70b is formed of a lanthanide oxide containing at least one lanthanide element and oxygen (O), but substantially free of at least one specified element. That is, the concentration of at least one specified element in the second layer portion 70b is zero or negligible. The thickness of the second layer portion 70b is thinner than that of the first layer portion 70a, preferably in the range of 0.3 nm to 0.8 nm.

[0049] Figure 3 This is a cross-sectional view schematically illustrating a second configuration example of this embodiment.

[0050] In this configuration example, the concentration of at least one specified element in the lanthanide oxide layer 70 increases from the storage layer 40 side toward the first electrode 10 side. Such a structure can be formed, for example, in the following manner.

[0051] First, such as Figure 4 As shown, a structure is formed between the first electrode 10 and the storage layer 40, comprising a lanthanide oxide layer 71 that does not contain a specified element and a specified element containing layer 72 that contains at least one specified element.

[0052] By heat-treating the structure described above, interdiffusion occurs between the lanthanide oxide layer 71 and the specified element-containing layer 72. This allows the formation of a lanthanide oxide layer 70 with the concentration gradient described above.

[0053] Figure 5 This is a cross-sectional view schematically illustrating the third configuration example of this embodiment.

[0054] In this configuration example, similar to the second configuration example, the concentration of at least one specified element in the lanthanide oxide layer 70 increases from the storage layer 40 side toward the first electrode 10 side. Furthermore, in this configuration example, the first electrode 10 contains at least one specified element. Such a structure can be formed, for example, in the following manner.

[0055] First, such as Figure 6 As shown, a structure comprising a lanthanide oxide layer 73 that does not contain a specified element is formed between the prepared first electrode 11 and the storage layer 40. The prepared first electrode 11 uses a material containing at least one specified element. For example, the prepared first electrode 11 can be a material in which at least one specified element is added to the main electrode material, or it can be a material formed only of at least one specified element.

[0056] By heat-treating the structure as described above, at least one specified element is diffused from the prepared first electrode 11 into the lanthanide oxide layer 73. This allows the formation of a lanthanide oxide layer 70 having the concentration gradient described above.

[0057] By using the first, second, and third configuration examples, it is possible to obtain an excellent magnetoresistive effect element that has the aforementioned effect.

[0058] (Second Implementation)

[0059] Next, the second embodiment will be described. Furthermore, the basic matters are the same as in the first embodiment, and the descriptions of matters described in the first embodiment will be omitted.

[0060] Figure 7 This is a cross-sectional view schematically showing the configuration of the magnetic storage device according to the second embodiment.

[0061] In this embodiment, similar to the first embodiment, a magnetoresistive element 30 is disposed between the first electrode 10 and the second electrode 20, and a lanthanide oxide layer 70 is disposed between the first electrode 10 and the storage layer 40.

[0062] However, in this embodiment, the stacking order of the first electrode 10, the second electrode 20, the storage layer 40, the reference layer 50, the tunnel barrier layer 60, and the lanthanide oxide layer 70 is reversed compared to the first embodiment. Therefore, in this embodiment, the first electrode 10 functions as the lower electrode of the magnetoresistive effect element 30, and the second electrode 20 functions as the upper electrode of the magnetoresistive effect element 30. Furthermore, in this embodiment, the lanthanide oxide layer 70 is disposed on the lower side of the storage layer 40, and the first electrode 10 is disposed on the lower side of the lanthanide oxide layer 70, with the lanthanide oxide layer 70 functioning as a substrate layer.

[0063] In this embodiment, similar to the first embodiment, a lanthanide oxide layer 70 containing at least one specified element selected from Ru, Rh, Pd, Re, Os, and Pt is disposed between the first electrode 10 and the storage layer 40. Therefore, in this embodiment, the same effects as in the first embodiment can be obtained.

[0064] Next, a specific configuration example of the magnetic storage device according to this embodiment will be described. Furthermore, in the following configuration example, only the first electrode 10, the storage layer 40, and the lanthanide oxide layer 70 are shown; however, on the upper side of the storage layer 40, a... Figure 7 The tunnel barrier layer 60, reference layer 50, and second electrode 20 are shown.

[0065] Figure 8 This is a cross-sectional view schematically showing the first configuration example of this embodiment.

[0066] The basic configuration of this embodiment is the same as that of the first embodiment of the first embodiment. That is, the lanthanide oxide layer 70 includes a first layer portion 70a and a second layer portion 70b disposed between the storage layer 40 and the first layer portion 70a. The basic configuration of the first layer portion 70a and the second layer portion 70b is the same as that of the first embodiment of the first embodiment.

[0067] Figure 9 This is a cross-sectional view schematically illustrating a second configuration example of this embodiment.

[0068] The basic configuration of this embodiment is the same as that of the second embodiment of the first embodiment. That is, the concentration of at least one specified element in the lanthanide oxide layer 70 increases from the storage layer 40 side toward the first electrode 10 side. The basic formation method of this embodiment is the same as that of the second embodiment of the first embodiment.

[0069] Figure 10 This is a cross-sectional view schematically illustrating the third configuration example of this embodiment.

[0070] The basic configuration of this embodiment is the same as that of the third embodiment of the first embodiment. That is, the concentration of at least one specified element in the lanthanide oxide layer 70 increases from the storage layer 40 side toward the first electrode 10 side, and the first electrode 10 contains at least one specified element. The basic formation method of this embodiment is the same as that of the third embodiment of the first embodiment.

[0071] By using the first, second, and third configuration examples, it is possible to obtain an excellent magnetoresistive effect element that has the aforementioned effect.

[0072] Several embodiments of the present invention have been described, but these embodiments are provided by way of example and are not intended to limit the scope of the invention. These novel embodiments can be implemented in various other ways and can be omitted, substituted, or modified in various ways without departing from the spirit of the invention. These embodiments or variations thereof are included in the scope or spirit of the invention, and are included in the scope of the invention as set forth in the claims and its equivalents.

[0073] [Explanation of Symbols]

[0074] 10: First electrode

[0075] 20: Second electrode

[0076] 30: Magnetoresistive element

[0077] 40: Storage layer (magnetic layer 1)

[0078] 50: Reference layer (second magnetic layer)

[0079] 60: Tunnel barrier layer (insulation layer)

[0080] 70: Lanthanide oxide layer

[0081] 70a: Part 1

[0082] 70b: Part 2.

Claims

1. A magnetic storage device comprising: Electrode 1; The second electrode; and A magnetoresistive element is disposed between the first electrode and the second electrode; The magnetoresistive effect element includes: First magnetic layer; Second magnetic layer; An insulating layer is disposed between the first magnetic layer and the second magnetic layer; and A lanthanide oxide layer is disposed between the first electrode and the first magnetic layer; The lanthanide oxide layer contains at least one lanthanide element selected from lanthanum (La), cerium (Ce), praseodymium (Pr), neodymium (Nd), promethium (Pm), samarium (Sm), europium (Eu), terbium (Tb), dysprosium (Dy), holmium (Ho), erbium (Er), thulium (Tm), ytterbium (Yb), and lutetium (Lu), oxygen (O), and at least one specified element selected from ruthenium (Ru), rhodium (Rh), palladium (Pd), rhenium (Re), osmium (Os), and platinum (Pt). The lanthanide oxide layer comprises a first portion and a second portion, each containing at least one lanthanide element and oxygen (O), wherein the concentration of the at least one specified element is higher in the first portion than in the second portion, and the second portion is located between the first portion and the first magnetic layer.

2. The magnetic storage device according to claim 1, wherein... The lanthanide oxide layer also contains boron (B).

3. The magnetic storage device according to claim 1, wherein... The lanthanide oxide layer also contains at least one element selected from iron (Fe), cobalt (Co) and nickel (Ni).

4. The magnetic storage device according to claim 1, wherein... The second part is in contact with the first magnetic layer.

5. The magnetic storage device according to claim 1, wherein... The thickness of the second part is thinner than the thickness of the first part.

6. The magnetic storage device according to claim 1, wherein... The thickness of the second part is in the range of 0.3 nm to 0.8 nm.

7. The magnetic storage device according to claim 1, wherein... The concentration of at least one specified element in the lanthanide oxide layer increases from the first magnetic layer side toward the first electrode side.

8. The magnetic storage device according to claim 1, wherein The thickness of the lanthanide oxide layer ranges from 0.6 nm to 3.0 nm.

9. The magnetic storage device according to claim 1, wherein The first electrode contains at least one of the specified elements.

10. The magnetic storage device according to claim 1, wherein The first magnetic layer has a variable magnetization direction, and the second magnetic layer has a fixed magnetization direction.

11. The magnetic storage device according to claim 1, wherein The first magnetic layer contains magnetic elements and boron (B).

12. The magnetic storage device according to claim 1, wherein The first magnetic layer contains at least one element selected from iron (Fe), cobalt (Co) and nickel (Ni) as well as boron (B).

13. The magnetic storage device according to claim 1, wherein The lanthanide oxide layer is disposed on the upper side of the first magnetic layer.

14. The magnetic storage device according to claim 1, wherein The lanthanide oxide layer is disposed on the lower side of the first magnetic layer.

15. The magnetic storage device according to claim 1, wherein When the at least one lanthanide element is represented as Ln and the at least one specified element is represented as X, the lanthanide oxide layer is represented as Ln2-aXaO3 layer, where 0 < a < 2.

16. The magnetic storage device according to any one of claims 1 to 15, wherein Part 2 does not contain the specified elements.

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