Spin-filtering magnetic tunnel junction, method of fabrication, and device

Abstract

The application provides a spin-filtering magnetic tunnel junction, comprising a first magnetic layer, a tunneling layer and a second magnetic layer; the first magnetic layer is connected with an external electrode and is used for generating a spin current; the tunneling layer is arranged between the first magnetic layer and the second magnetic layer and is used for isolating the first magnetic layer and the second magnetic layer; and the second magnetic layer has anti-ferromagnetism and is used for filtering the spin current. The second magnetic layer with anti-ferromagnetism is arranged, the spin current can be filtered, and a huge tunneling magnetoresistance can be realized. The application further provides a preparation method and equipment of the spin-filtering magnetic tunnel junction.

Description

Technical Field

[0001] This invention relates to the field of data storage technology, and in particular to a spin-filtered magnetic tunnel junction, its preparation method, and equipment. Background Technology

[0002] Currently, memory is primarily based on semiconductor transistors. However, advanced integrated circuit manufacturing processes are constrained by quantum effects, leading to leakage currents in semiconductors due to tunneling, and Moore's Law is failing. Meanwhile, spintronic memory devices, such as magnetic tunnel junctions (MTJs), are receiving significant attention from industry due to their advantages such as non-volatile storage, ultra-low power consumption, and high read / write cycles. MTJs are of great importance to integrated circuits and information technology in the post-Moore's Law era; however, the tunneling magnetoresistivity of MTJs is currently insufficient, and existing technologies are still difficult to industrialize.

[0003] In realizing the concept disclosed herein, the inventors discovered at least the following problems in the related technology: the tunneling magnetic reluctance of the magnetic tunnel junction is not high enough; and it is difficult to achieve industrial production. Summary of the Invention

[0004] To overcome at least one of the above problems, this disclosure provides a spin-filtered magnetic tunnel junction, comprising:

[0005] First magnetic layer, tunneling layer, and second magnetic layer;

[0006] The first magnetic layer is connected to an external electrode and is used to generate a spin current;

[0007] The tunneling layer is disposed between the first magnetic layer and the second magnetic layer to isolate the first magnetic layer and the second magnetic layer.

[0008] The second magnetic layer has antiferromagnetism to filter the spin current.

[0009] According to embodiments of this disclosure, both the first magnetic layer and the second magnetic layer have vertical anisotropy.

[0010] According to an embodiment of this disclosure, the first magnetic layer includes a ferromagnetic layer with magnetic moments arranged in a vertical direction; the second magnetic layer includes a non-collinear antiferromagnetic weak magnetic layer with magnetic moments arranged in a vertical direction.

[0011] According to embodiments of this disclosure, the material of the tunneling layer includes one or more of insulating materials and multiferroic materials.

[0012] According to embodiments of this disclosure, the ferromagnetic material of the first magnetic layer includes elemental ferromagnetic material, alloy ferromagnetic material, or magnetic metal oxide.

[0013] This disclosure also provides a method for preparing a spin-filtering magnetic tunnel junction, including:

[0014] A substrate is selected, and a first magnetic layer and a tunneling layer are sequentially grown on the substrate.

[0015] A tunnel junction region is fabricated on the tunneling layer using micro-nano fabrication methods, and a second magnetic layer and a top electrode are filled within the tunnel junction region.

[0016] The first magnetic layer and the tunneling layer are etched into strips, wherein the tunnel junction region is at the center of the tunneling layer;

[0017] Then etch the portion outside the tunnel junction region onto the substrate.

[0018] This disclosure also provides a storage device comprising any of the spin-filtered magnetic tunnel junctions described above, wherein a plurality of the spin-filtered magnetic tunnel junctions are arranged in an array on a substrate to form an MRAM storage array.

[0019] Based on the above technical solution, it can be seen that this disclosure has at least the following beneficial effects:

[0020] This disclosure provides a spin-filtering magnetic tunnel junction, comprising: a first magnetic layer, a tunneling layer, and a second magnetic layer; the first magnetic layer is connected to an external electrode and is used to generate a spin current; the tunneling layer is disposed between the first and second magnetic layers and is used to isolate the first and second magnetic layers; the second magnetic layer has antiferromagnetism to filter the spin current. This invention, by incorporating a second magnetic layer with antiferromagnetism, can filter the spin current, achieving a high tunneling magnetoresistivity, and the vertically oriented spin-filtering magnetic tunnel junction can be industrially produced. Attached Figure Description

[0021] To gain a more complete understanding of this disclosure and its advantages, reference will now be made to the following description taken in conjunction with the accompanying drawings, in which:

[0022] Figure 1 This is a schematic diagram of the structure of a spin-filtering magnetic tunnel junction according to an embodiment of this disclosure;

[0023] Figure 2a This is a schematic flowchart of the method for preparing a spin-filtering magnetic tunnel junction according to an embodiment of the present disclosure;

[0024] Figure 2b This is a schematic flowchart of the method for preparing a spin-filtered magnetic tunnel junction according to an embodiment of the present disclosure.

[0025] [Explanation of Labels in the Attached Image]

[0026] 1-First magnetic layer

[0027] 2-Tunneling Layer

[0028] 3-Second magnetic layer

[0029] 4-substrate

[0030] 5- Protective insulation layer

[0031] 6-Top Electrode Detailed Implementation

[0032] The embodiments of the present disclosure will now be described with reference to the accompanying drawings. However, it should be understood that these descriptions are exemplary only and are not intended to limit the scope of the disclosure. In the following detailed description, numerous specific details are set forth to provide a thorough understanding of the embodiments of the present disclosure for ease of explanation. However, it will be apparent that one or more embodiments may be practiced without these specific details. Furthermore, descriptions of well-known structures and techniques are omitted in the following description to avoid unnecessarily obscuring the concepts of the present disclosure.

[0033] The terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit this disclosure. The terms “comprising,” “including,” etc., as used herein indicate the presence of the stated features, steps, operations, and / or components, but do not exclude the presence or addition of one or more other features, steps, operations, or components.

[0034] All terms used herein (including technical and scientific terms) have the meanings commonly understood by those skilled in the art, unless otherwise defined. It should be noted that the terms used herein are to be interpreted in a manner consistent with the context of this specification, and not in an idealized or overly rigid way.

[0035] This invention is described in detail with reference to the schematic diagrams. When detailing the embodiments of this invention, for ease of explanation, the schematic diagrams illustrating the device structure may be partially enlarged, not according to general proportions. Furthermore, these schematic diagrams are merely examples and should not limit the scope of protection of this invention. In actual fabrication, the three-dimensional spatial dimensions of length, width, and depth should be included.

[0036] As described in the background section, magnetic tunnel junctions (MTJs) are widely used in spintronic devices due to their advantages such as high-speed read / write capabilities, high integration density, and unlimited rewrite cycles. Tunneling magnetoresistivity is a core indicator of TJ performance, and it is related to the resistance difference between parallel and antiparallel ferromagnetic layers. Higher tunneling magnetoresistivity results in higher data read reliability. TJJs with high tunneling magnetoresistivity are widely used in high-density hard drive read heads and are crucial for the development of various novel spintronic devices, greatly promoting the industrialization of magnetic tunnel junctions.

[0037] Figure 1 This is a schematic diagram of the structure of a spin-filtering magnetic tunnel junction according to an embodiment of this disclosure; as shown... Figure 1 As shown, this disclosure provides a spin-filtering magnetic tunnel junction, comprising: a first magnetic layer 1, a tunneling layer 2, and a second magnetic layer 3; the first magnetic layer 1 is connected to an external electrode and is used to generate a spin current; the tunneling layer 2 is disposed between the first magnetic layer 1 and the second magnetic layer 3 to isolate the first magnetic layer 1 and the second magnetic layer 3, thereby generating a tunneling effect; the second magnetic layer 3 has antiferromagnetism to filter the spin current.

[0038] When the external magnetic field strength is low, the second magnetic layer 3, due to its antiferromagnetism, hinders the passage of spin current, resulting in a smaller spin current and higher magnetoresistance. As the external magnetic field strength increases, the filtering effect on spin current deteriorates until the external magnetic field strength reaches a critical value. At this point, the electromagnetic direction of the second magnetic layer 3 is completely magnetized by the external magnetic field, the filtering effect disappears, and the passing spin current becomes larger while the magnetoresistance decreases. The critical value is related to the thickness of the second magnetic layer 3; the greater the thickness, the stronger the antiferromagnetism, and the higher the critical value of the external magnetic field strength.

[0039] The spin-filtering magnetic tunnel junction of this embodiment can filter spin current by setting a second magnetic layer 3 with antiferromagnetism. The spin-filtering magnetic tunnel junction provided in this embodiment can achieve a huge tunneling magnetic resistivity.

[0040] As an optional embodiment, the ferromagnetic material of the first magnetic layer 1 can be an elemental ferromagnetic material, an alloy ferromagnetic material, or a magnetic metal oxide, such as Co, FePt, MnGa, or La. 0.7 Sr 0.3 Magnetic materials such as MnO3.

[0041] As an optional embodiment, the tunneling layer 2 can be made of one or more of an insulating material or a multiferroic material. The insulating material is such as aluminum oxide, magnesium oxide or hafnium oxide, and the multiferroic material is such as BaTiO3, PbTiO3 and their doped multiferroic materials.

[0042] The second magnetic layer 3 is antiferromagnetic, which can filter spin current and generate a huge tunneling magnetoresistance effect. The ferromagnetic material of the second magnetic layer 3 is a non-collinear antiferromagnetic weak magnetic material, such as Mn3Sn.

[0043] As an optional embodiment, both the first magnetic layer 1 and the second magnetic layer 3 have vertical anisotropy.

[0044] The first magnetic layer 1 includes a ferromagnetic layer with magnetic moments arranged in a vertical direction; the second magnetic layer 3 includes a non-collinear antiferromagnetic weak magnetic layer with magnetic moments arranged in a vertical direction.

[0045] It should be noted that if the ferromagnetic layer with perpendicular magnetic anisotropy and the non-collinear antiferromagnetic weak magnetic layer with perpendicular magnetic anisotropy provided in this disclosure can maintain their physical properties at room temperature, a magnetic tunnel junction with high tunneling magnetic resistivity at room temperature can be realized.

[0046] In this embodiment, the spin-filtering magnetic tunnel junction exhibits extremely high magnetoresistance (MRT) at low external magnetic field strengths, approximately on the order of ten megohms, equivalent to insulation. When the external magnetic field strength reaches a critical value, the MTR decreases, becoming equivalent to conductor. This critical value is related to the thickness of the second magnetic layer 3; a greater thickness results in stronger antiferromagnetism and a higher critical value for the external magnetic field strength. Experiments show that when the thickness of the second magnetic layer 3 is 60 nm, the critical value for the magnetic field strength is 1 T. The spin-filtering magnetic tunnel junction provided in this disclosure can achieve magnetic tunneling resistance at low temperatures and obtain a large magnetic tunneling resistivity. It can also be used to realize magnetic field-driven diodes. Furthermore, the vertical magnetic tunnel junction facilitates integration and industrialization, representing a significant breakthrough in industrial production.

[0047] Figure 2a This is a schematic flowchart of the method for preparing a spin-filtering magnetic tunnel junction according to an embodiment of the present disclosure;

[0048] Figure 2b This is a schematic flowchart illustrating the fabrication method of the spin-filtered magnetic tunnel junction according to an embodiment of this disclosure. Figure 2a and Figure 2b As shown, this disclosure also provides a method for preparing a spin-filtered magnetic tunnel junction, which includes the following steps:

[0049] S201. Select substrate 4, and grow the first magnetic layer 1 and the tunneling layer 2 sequentially on substrate 4.

[0050] In the embodiments of this disclosure, a first magnetic layer 1 and a tunneling layer 2 can be grown sequentially by means of magnetron sputtering, laser pulse deposition or molecular beam epitaxy, for example, the thickness of the first magnetic layer 1 is 5nm-100nm and the thickness of the tunneling layer 2 is 1nm-3nm.

[0051] S202. A tunnel junction region is prepared on the tunneling layer 2 using micro-nano fabrication methods, and a second magnetic layer 3 and a top electrode 6 are filled in the tunnel junction region.

[0052] In the embodiments disclosed herein, the second magnetic layer 3 can be grown by means of magnetron sputtering, laser pulse deposition or molecular beam epitaxy, and the second magnetic layer 3 is a non-collinear antiferromagnetic weak magnetic material. The thicker the second magnetic layer 3, the better the effect of filtering spin current.

[0053] S203. The first magnetic layer 1 and the tunneling layer 2 are etched into a strip shape, wherein the tunnel junction region is in the center of the tunneling layer 2, and the exposed first magnetic layer 1 is the bottom electrode.

[0054] S204, then etch the portion outside the tunnel junction region to the substrate 4.

[0055] To facilitate the testing or application of the spin-filtered magnetic tunnel junction, after fabricating the tunnel junction, step S205 is required to grow a protective insulating layer 5 around the tunnel junction. In this disclosure, the protective insulating layer 5 can be grown by radio frequency magnetron sputtering, laser pulse deposition, or other methods. The material of the protective insulating layer 5 can be Al2O3, SiO2, etc. The thickness of the protective insulating layer 5 needs to be at least greater than the thickness of the tunneling layer 2 and the second magnetic layer 3. Finally, step S206 is required to fabricate external electrodes through micro / nano fabrication and extend the top electrode 6 and the bottom electrode.

[0056] It should be noted that the preparation method of the spin-filtering magnetic tunnel junction in the embodiments of this disclosure corresponds to the spin-filtering magnetic tunnel junction in the embodiments of this disclosure. The description of the preparation method of the spin-filtering magnetic tunnel junction is specifically referred to in the spin-filtering magnetic tunnel junction section, and will not be repeated here.

[0057] This disclosure also provides a storage device, the storage device including... Figure 1 Spin-filtered magnetic tunnel junction of any embodiment.

[0058] In specific applications, the aforementioned spin-filtered magnetic tunnel junctions can be arranged in an array to form a conventional MRAM memory array. This memory array can be used independently or integrated into a general MRAM memory array device, such as a processor, application-specific integrated circuit, or system-on-a-chip.

[0059] It should be noted that, for the sake of simplicity, the foregoing method embodiments are all described as a series of actions. However, those skilled in the art should understand that the present invention is not limited to the described order of actions, because according to the present invention, some steps can be performed in other orders or simultaneously. Furthermore, those skilled in the art should also understand that the embodiments described in the specification are preferred embodiments, and the actions and modules involved are not necessarily essential to the present invention.

[0060] In the above embodiments, the descriptions of each embodiment have different focuses. For parts not described in detail in a certain embodiment, please refer to the relevant descriptions of other embodiments.

[0061] The specific embodiments described above further illustrate the purpose, technical solution, and beneficial effects of the present invention. It should be understood that the above descriptions are merely specific embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A spin-filtering magnetic tunnel junction, characterized in that, include: First magnetic layer, tunneling layer, and second magnetic layer; The first magnetic layer is connected to an external electrode and is used to generate a spin current; The tunneling layer is disposed between the first magnetic layer and the second magnetic layer to isolate the first magnetic layer and the second magnetic layer. The second magnetic layer has antiferromagnetism to filter the spin current; Specifically, when the external magnetic field strength is low, the magnetoresistance value is in the tens of megohms, which is equivalent to insulation; when the external magnetic field strength reaches a critical value, the magnetoresistance value is small, which is equivalent to conductor; wherein the thickness of the second magnetic layer is 60nm, and the critical value of the magnetic field strength is 1T.

2. The spin-filtering magnetic tunnel junction according to claim 1, characterized in that, Both the first magnetic layer and the second magnetic layer have vertical anisotropy.

3. The spin-filtering magnetic tunnel junction according to claim 2, characterized in that, The first magnetic layer includes a ferromagnetic layer with magnetic moments arranged in a vertical direction; the second magnetic layer includes a non-collinear antiferromagnetic weak magnetic layer with magnetic moments arranged in a vertical direction.

4. The spin-filtering magnetic tunnel junction according to claim 1, characterized in that, The material of the tunneling layer includes one or more of insulating materials and multiferroic materials.

5. The spin-filtering magnetic tunnel junction according to claim 1, characterized in that, The ferromagnetic material of the first magnetic layer includes elemental ferromagnetic materials, alloy ferromagnetic materials, or magnetic metal oxides.

6. A method for preparing a spin-filtering magnetic tunnel junction, used to prepare a spin-filtering magnetic tunnel junction as described in any one of claims 1-5, characterized in that, include: A substrate is selected, and a first magnetic layer and a tunneling layer are sequentially grown on the substrate. A tunnel junction region is fabricated on the tunneling layer using micro-nano fabrication methods, and a second magnetic layer and a top electrode are filled within the tunnel junction region. The first magnetic layer and the tunneling layer are etched into strips, wherein the tunnel junction region is at the center of the tunneling layer; Then etch the portion outside the tunnel junction region onto the substrate.

7. A storage device, characterized in that, The storage device includes a spin-filtered magnetic tunnel junction as described in any one of claims 1-5, wherein a plurality of the spin-filtered magnetic tunnel junctions are arranged in an array on a substrate to form an MRAM storage array.

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