MTJ and Memory

Abstract

The present application provides an MTJ and a memory. The MTJ includes a reference layer, a barrier layer, and a free layer stacked in sequence, and the free layer includes a first magnetic layer, a first coupling layer, a second magnetic layer, a second coupling layer, and a third magnetic layer stacked in sequence. In this solution, on the traditional MTJ, the thickness of the free layer magnetic film is increased, and by increasing the thickness, the energy barrier height is relatively large, ensuring good storage ability of the MTJ, thereby improving the data storage ability of the MTJ and better alleviating the problem of poor data storage ability of the memory in the prior art.

Description

Technical Field

[0001] This application relates to the field of memories, and more particularly, to an MTJ and a memory. Background Art

[0002] STT-MRAM (Spin Torque Transfer Magnetic Random Access Memory) has the advantages of simple circuit design, fast read / write speed, and non-volatility. Its basic structure is a magnetic tunnel junction (MTJ), which is composed of a free layer, a reference layer, and a barrier layer sandwiched between the two. Among them, the magnetization direction of the reference layer is fixed and does not flip during device operation; the magnetization direction of the free layer is collinear (parallel or anti-parallel) with the reference layer. By utilizing the spin torque of electrons, the magnetization direction of the free layer is flipped to achieve parallel (lower resistance) or anti-parallel (higher resistance) magnetization directions between the reference layer and the free layer, thereby realizing writing "0" or "1".

[0003] For the free layer, the switching between "0" and "1" in MRAM (Magnetic Random Access Memory) is achieved by flipping the free layer. Therefore, the easier the free layer flips (the smaller Hc), the smaller the required driving force (current / voltage), and the lower the power consumption; however, if Hc is too small, there is a risk that the read current / thermal disturbance will flip the free layer. Therefore, MRAM is required to have a relatively high energy barrier height Δ.

[0004] According to the calculation formula of the energy barrier height Δ, on the premise that the free layer material / structure has not changed much, pSTT-MRAM (perpendicular STT-MRAM) is mainly related to the perpendicular magnetic anisotropy field Hk of the free layer, the volume of the MTJ, and the thickness of the free layer magnetic film, as described by the following formula:

[0005]

[0006] However, simply increasing the thickness t will result in a decrease in Hk; while increasing Hk will reduce the thickness of the magnetic film. Therefore, there is an urgent need for an improved structure to increase the thickness of the free layer magnetic film while maintaining the non-decay of Hk to increase the data retention ability.

[0007] The above information disclosed in the background art section is only used to enhance the understanding of the background art of the technology described in this article. Therefore, the background art may contain certain information that is not prior art known to those skilled in the art in this country. Summary of the Invention

[0008] The main object of the present application is to provide an MTJ and a memory, so as to solve the problem of poor data storage ability of the memory in the prior art.

[0009] To achieve the above object, according to one aspect of the present application, there is provided an MTJ, including a reference layer, a barrier layer, and a free layer stacked in sequence, wherein the free layer includes a first magnetic layer, a first coupling layer, a second magnetic layer, a second coupling layer, and a third magnetic layer stacked in sequence.

[0010] Optionally, at least one of the first magnetic layer, the second magnetic layer, and the third magnetic layer is a stacked structure, and the stacked structure includes a plurality of stacked structural layers.

[0011] Optionally, the stacked structure includes an alternating part and a non-alternating part. The alternating part includes a first structural layer and a second structural layer that are alternately arranged in sequence, wherein the number of the first structural layer and the second structural layer is the same, and the non-alternating part is the first structural layer. The material of the first structural layer includes at least one of Co, Fe, CoFe, FeB, CoB, CoFeB, and Heusler alloy materials, and the material of the second structural layer includes at least one of Pt, Pd, and Ni.

[0012] Optionally, the first magnetic layer is not the stacked structure, the second magnetic layer is the stacked structure, and the third magnetic layer is not the stacked structure.

[0013] Optionally, the materials of the first magnetic layer and the third magnetic layer are both magnetic materials. The material of the first magnetic layer includes at least one of Co, Fe, CoFe, FeB, CoB, CoFeB, and Heusler alloy materials, and the material of the third magnetic layer includes at least one of Co, Fe, CoFe, FeB, CoB, CoFeB, and Heusler alloy materials.

[0014] Optionally, the material of at least one of the first coupling layer and the second coupling layer is an antiferromagnetic coupling material.

[0015] Optionally, the material of the first coupling layer includes at least one of Ir, Ru, W, Mo, and Ta, and the material of the second coupling layer includes at least one of Ir, Ru, W, Mo, and Ta.

[0016] Optionally, the first coupling layer is located on the side of the first magnetic layer away from the barrier layer.

[0017] Optionally, the material of the barrier layer includes MgO, AlO X , MgAlO X , TiO X , TaOX 、GaO X and FeO X at least one of them.

[0018] To achieve the above object, according to another aspect of the present application, there is provided a memory including any one of the above-mentioned MTJs.

[0019] Applying the technical solution of the present application, in the MTJ, there are three layers in total, namely a reference layer, a barrier layer and a free layer, and these three layers are stacked in sequence. The free layer includes five layers, namely a first magnetic layer, a first coupling layer, a second magnetic layer, a second coupling layer and a third magnetic layer, and these five layers are stacked in sequence. In this solution, on the traditional MTJ, the thickness of the free layer magnetic film is increased. By increasing the thickness, the height of the energy barrier is relatively large, ensuring that the MTJ has good storage ability, and thus the data storage ability of the MTJ can be improved, thereby better alleviating the problem of poor data storage ability of the memory in the prior art. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] The accompanying drawings forming a part of this application are used to provide a further understanding of the application. The illustrative embodiments of the application and their descriptions are used to explain the application and do not constitute an improper limitation to the application. In the drawings:

[0021] Figure 1 shows a schematic structural diagram of an MTJ according to an embodiment of the present application;

[0022] Figure 2 shows a schematic structural diagram of a stacked structure according to an embodiment of the present application;

[0023] Figure 3 shows a schematic structural diagram of another MTJ according to an embodiment of the present application;

[0024] Figure 4 shows a schematic structural diagram of yet another MTJ according to an embodiment of the present application.

[0025] Among them, the above-mentioned drawings include the following reference numerals:

[0026] 10. Barrier layer; 20. First magnetic layer; 30. First coupling layer; 40. Second magnetic layer; 41. First structural layer; 42. Second structural layer; 50. Second coupling layer; 60. Third magnetic layer; 70. Cover layer; 80. Reference layer. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0027] It should be noted that the following detailed description is exemplary and is intended to provide further explanation of the present application. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the technical field to which this application belongs.

[0028] It should be noted that the terms used herein are only for describing specific embodiments and are not intended to limit the exemplary embodiments according to the present application. As used herein, unless the context clearly indicates otherwise, the singular forms are also intended to include the plural forms. In addition, it should be understood that when the terms "comprising" and / or "including" are used in this specification, they specify the presence of features, steps, operations, devices, components, and / or combinations thereof.

[0029] It should be understood that when an element (such as a layer, film, region, or substrate) is described as being "on" another element, the element can be directly on the other element, or there can also be an intermediate element. Moreover, in the specification and claims, when an element is described as "connected" to another element, the element can be "directly connected" to the other element, or "connected" to the other element through a third element.

[0030] As introduced in the background art, the memory data retention ability in the prior art is poor. To solve the above problems, the present application proposes a MTJ and a memory.

[0031] According to an embodiment of the present application, a MTJ is provided. Figure 1 It is a schematic structural diagram of a MTJ according to an embodiment of the present application. As Figure 1 shown, the MTJ includes a reference layer 80, a barrier layer 10, and a free layer stacked in sequence. The above free layer includes a first magnetic layer 20, a first coupling layer 30, a second magnetic layer 40, a second coupling layer 50, and a third magnetic layer 60 stacked in sequence.

[0032] In the above MTJ, a total of three layers are included, namely the reference layer, the barrier layer, and the free layer. And these three layers are stacked in sequence. The free layer includes five layers, namely the first magnetic layer, the first coupling layer, the second magnetic layer, the second coupling layer, and the third magnetic layer. And these five layers are stacked in sequence. In this solution, on the traditional MTJ, the thickness of the free layer magnetic film is increased. By increasing the thickness, the height of the energy barrier is relatively large, ensuring that the MTJ has a good retention ability, and thus the data retention ability of the MTJ can be improved, thereby better alleviating the problem of poor memory data retention ability in the prior art.

[0033] In an embodiment of the present application, as Figure 1As shown, at least one of the above-mentioned first magnetic layer 20, second magnetic layer 40, and third magnetic layer 60 is a stacked structure, and the stacked structure includes a plurality of stacked structural layers. In this embodiment, the plurality of structural layers make the thickness of the free layer greater, thereby further increasing the data storage capacity.

[0034] Specifically, the MTJ further includes a capping layer, such as Figure 1 As shown, the capping layer is stacked above the free layer, and the material of the capping layer includes at least one of MgO, AlO X , MgAlO X , TiO X , TaO X , GaO X and FeO X . It should be noted that X in the chemical formulas of these materials represents the number of corresponding atoms in a molecule. Although X is used to represent the number of corresponding atoms in multiple chemical formulas, these X values can be different and are not necessarily the same.

[0035] In another embodiment of the present application, as Figure 2 shown, the above-mentioned stacked structure includes an alternating part and a non-alternating part. The alternating part includes a first structural layer 41 and a second structural layer 42 that are alternately arranged in sequence. Among them, the number of the first structural layer 41 and the second structural layer 42 is the same. The non-alternating part is the first structural layer 41. The material of the first structural layer 41 includes at least one of Co, Fe, CoFe, FeB, CoB, CoFeB, and Heusler alloy materials. The material of the second structural layer 42 includes at least one of Pt, Pd, and Ni. In this embodiment, the stacked structure includes a plurality of first structural layers 41 and a plurality of second structural layers 42, further making the stacked structure thicker, and further making the thickness of the free layer greater.

[0036] In yet another embodiment of the present application, the first magnetic layer is not the above-mentioned stacked structure, the second magnetic layer is the above-mentioned stacked structure, and the third magnetic layer is not the above-mentioned stacked structure. In this embodiment, setting the second magnetic layer as a stacked structure can make the magnetic layer in contact with the barrier layer or the capping layer above the free layer have a better contact interface, thereby forming a more matching lattice transition, reducing defects, and enhancing PMA and spin polarization rate.

[0037] Specifically, in one embodiment, the second magnetic layer is a stacked structure, the first structural layer is Co, the second structural layer is Pt, including 2 Co and 2 Pt. The 2 Co and 2 Pt constitute the alternating part, and the non-alternating part is Co.

[0038] In addition, it should be noted that the number of the above-mentioned first structural layer and the second structural layer is not limited to 2, and may also be 3, 4 or other numbers. Those skilled in the art can select the appropriate number of the first structural layer and the second structural layer according to needs.

[0039] In another embodiment of the present application, the materials of the above-mentioned first magnetic layer and the third magnetic layer are both magnetic materials. The material of the first magnetic layer includes at least one of Co, Fe, CoFe, FeB, CoB, CoFeB and Heusler alloy materials, and the material of the third magnetic layer includes at least one of Co, Fe, CoFe, FeB, CoB, CoFeB and Heusler alloy (Hassler) materials. In this embodiment, using the above materials can make the magnetic layer in contact with the covering layer above the barrier layer or the free layer have a better contact interface, so as to form a more matching lattice transition, reduce defects, and improve PMA and spin polarization rate.

[0040] In a specific embodiment of the present application, the material of at least one of the above-mentioned first coupling layer and the second coupling layer is an antiferromagnetic coupling material. This can reduce the equivalent total magnetic moment of the free layer, thereby reducing the critical switching current and at the same time reducing the stray field effect of the free layer on the reference layer.

[0041] In yet another specific embodiment of the present application, the material of the first coupling layer includes at least one of Ir, Ru, W, Mo and Ta, and the material of the second coupling layer includes at least one of Ir, Ru, W, Mo and Ta.

[0042] In yet another embodiment of the present application, in order to make the storage effect of the MTJ better, the first coupling layer is located on the side of the first magnetic layer away from the barrier layer.

[0043] In still another embodiment of the present application, the material of the barrier layer includes at least one of MgO, AlO X , MgAlO X , TiO X , TaO X , GaO X and FeO X . In this embodiment, using the above materials to make the barrier layer can make the barrier layer have a good refractory insulation effect and further improve the performance of the MTJ.

[0044] The present application also provides a memory, which includes any one of the above-mentioned MTJs.

[0045] In the above-mentioned memory, since any one of the above MTJs is included, in this MTJ, the thickness of the free layer magnetic film is increased, and by increasing the thickness, the energy barrier height is made larger, ensuring that the storage ability of the MTJ is better. Furthermore, the data storage ability of the MTJ can be improved, thus better alleviating the problem of poor data storage ability of the memory in the prior art.

[0046] In order for those skilled in the art to more clearly understand the technical solution of the present application, the following will illustrate the technical solution and technical effects of the present application with specific embodiments.

[0047] Embodiment 1

[0048] As Figure 3 shown, the material of the barrier layer 10 of the MTJ is MgO, and it further includes a first magnetic layer 20. The material of the first coupling layer 30 is Mo, the first structural layer 41 is Co, the second structural layer 42 is Pt. Two Cos and two Pts form an alternating part, and one Co is a non-alternating part. The material of the second coupling layer 50 is Ru, and it further includes a third magnetic layer 60 and a covering layer 70. The material of the covering layer 70 is MgO.

[0049] Embodiment 2

[0050] As Figure 4 shown, the material of the barrier layer 10 of the MTJ is MgO, and it further includes a first magnetic layer 20. The material of the first coupling layer 30 is Ir, the first structural layer 41 is Co, the second structural layer 42 is Ni. One Co and one Ni form an alternating part, and one Co is a non-alternating part. The material of the second coupling layer 50 is Ir, and it further includes a third magnetic layer 60 and a covering layer 70. The material of the covering layer 70 is MgO.

[0051] From the above description, it can be seen that the above embodiments of the present application achieve the following technical effects:

[0052] 1) For the MTJ of the present application, on the basis of the traditional MTJ, the thickness of the free layer magnetic film is increased. By increasing the thickness, the energy barrier height is made larger, ensuring that the storage ability of the MTJ is better. Furthermore, the data storage ability of the MTJ can be improved, thus better alleviating the problem of poor data storage ability of the memory in the prior art.

[0053] 2) For the memory of the present application, since any one of the above MTJs is included, in this MTJ, the thickness of the free layer magnetic film is increased. By increasing the thickness, the energy barrier height is made larger, ensuring that the storage ability of the MTJ is better. Furthermore, the data storage ability of the MTJ can be improved, thus better alleviating the problem of poor data storage ability of the memory in the prior art.

[0054] The above are only the preferred embodiments of the present application and are not intended to limit the present application. For those skilled in the art, various modifications and variations can be made to the present application. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included within the protection scope of the present application.

Claims

1. A MTJ, characterized in that, It includes a reference layer, a barrier layer, and a free layer stacked in sequence. The free layer includes a first magnetic layer, a first coupling layer, a second magnetic layer, a second coupling layer, and a third magnetic layer stacked in sequence. At least one of the first magnetic layer, the second magnetic layer, and the third magnetic layer is a stacked structure. The stacked structure includes a plurality of stacked structural layers. The first magnetic layer is not the stacked structure. The second magnetic layer is the stacked structure. The third magnetic layer is not the stacked structure. The stacked structure is composed of an alternating part and a non-alternating part stacked in sequence. The alternating part includes a first structural layer and a second structural layer alternating in sequence. Wherein, the number of the first structural layer and the second structural layer is the same. The non-alternating part is the first structural layer. The material of the first structural layer includes at least one of Co, Fe, CoFe, FeB, CoB, CoFeB, and Heusler alloy materials. The material of the second structural layer includes at least one of Pt, Pd, and Ni.

2. The MTJ according to claim 1, characterized in that, The materials of the first magnetic layer and the third magnetic layer are both magnetic materials. The material of the first magnetic layer includes at least one of Co, Fe, CoFe, FeB, CoB, CoFeB, and Heusler alloy materials. The material of the third magnetic layer includes at least one of Co, Fe, CoFe, FeB, CoB, CoFeB, and Heusler alloy materials.

3. The MTJ according to claim 1, wherein The material of at least one of the first coupling layer and the second coupling layer is an antiferromagnetic coupling material.

4. The MTJ according to claim 3, wherein The material of the first coupling layer includes at least one of Ir, Ru, W, Mo, and Ta. The material of the second coupling layer includes at least one of Ir, Ru, W, Mo, and Ta.

5. The MTJ according to claim 1, wherein The first coupling layer is located on the side of the first magnetic layer away from the barrier layer.

6. The MTJ according to any one of claims 1 to 5, characterized in that, The materials of the barrier layer include MgO, AlO X , MgAlO X , TiO X , TaO X , GaO X and at least one of FeO X .

7. A memory, characterized in that, It includes the MTJ according to any one of claims 1 to 6.

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