Magnetic tunnel junction

Abstract

The invention provides a magnetic tunnel junction. The magnetic tunnel junction comprises a substrate; the reference layer is located above the substrate, and the reference layer is made of a ferromagnetic metal material or made of a two-dimensional magnetic heterostructure-2H-VSeTe material; an insulating layer over the reference layer, the insulating layer being formed of a non-magnetic material; and the free layer is positioned above the insulating layer, and the free layer is formed by the two-dimensional magnetic heterojunction material (2H-VSeTe). The two-dimensional transverse heterojunction magnetic material 2H-VSeTe is used as a free layer or a reference layer, and a regulation strategy is combined, so that the magnetic performance and the stability of the magnetic tunnel junction are improved, and a new solution is provided for realizing a high-performance and low-power-consumption magnetoelectric random access memory device by optimizing a VCMA coefficient. The innovation not only promotes the development of the magnetic storage technology, but also provides powerful technical support for intelligentization, miniaturization and integration of future electronic systems.

Description

Technical Field

[0001] The present invention relates to the field of microelectronic technology, and in particular to a magnetic tunnel junction. Background Art

[0002] With the rapid development of information technology, the demand for data storage has increased dramatically. The limitations of traditional magnetic random access memory (MRAM) have gradually become apparent, and it is difficult to meet the high requirements of modern data storage. In this context, magnetoelectric random access memory (MeRAM) has emerged as an emerging technology, and has become the focus of storage technology research with its ultra-low power consumption, high scalability and non-volatile storage characteristics.

[0003] The core of MeRAM technology lies in its unique read and write mechanism, which uses a spin transfer torque (STT) or spin-orbit torque (SOT) magnetization switching mechanism combined with voltage-controlled magnetic anisotropy (VCMA) technology. This mechanism enables MeRAM to achieve efficient and low-power reading and writing of information, thereby greatly improving storage performance. However, despite the many advantages of MeRAM technology, its further development still faces challenges. How to further improve the efficiency of VCMA and achieve precise control of magnetic anisotropy energy (MAE) has become a key factor restricting the performance improvement of MeRAM technology.

[0004] In MeRAM technology, magnetic tunnel junction (MTJ) materials play a vital role. The general structure of MTJ materials is a sandwich structure of ferromagnetic layer / non-magnetic insulating layer / ferromagnetic layer, and its working principle is based on the spin-related tunneling effect. When the magnetization directions of the two ferromagnetic layers are parallel to each other, electrons can pass through the non-magnetic insulating layer more easily, forming a low-resistance state; when the magnetization directions of the two ferromagnetic layers are anti-parallel, it becomes more difficult for electrons to pass through the non-magnetic insulating layer, forming a high-resistance state. This information storage method based on changes in magnetization direction gives MeRAM technology the characteristics of non-volatility and low power consumption.

[0005] However, the performance of existing ferromagnetic layer materials is still insufficient, resulting in insufficient sensitivity of magnetic tunnel junction materials. In order to break through this bottleneck, researchers began to explore the application of two-dimensional magnetic materials in magnetic tunnel junctions to replace traditional ferromagnetic layer materials. Due to their unique crystal structure and magnetic properties, two-dimensional magnetic materials have shown great potential in the design of new spin electronic devices, especially magnetic memory devices. By using two-dimensional magnetic materials as ferromagnetic layers in magnetic tunnel junctions, it is expected to further improve the sensitivity and performance of MTJ materials, thereby promoting the further development of MeRAM technology. Summary of the invention

[0006] In view of the above-mentioned problems existing in the prior art, the present application provides a two-dimensional magnetic heterojunction material and application.

[0007] In one aspect, the present invention provides a magnetic tunnel junction, comprising:

[0008] substrate;

[0009] A reference layer, located above the substrate, wherein the reference layer is formed of a ferromagnetic metal material or the two-dimensional magnetic heterojunction material-2H-VSeTe according to claim 1;

[0010] an insulating layer, located above the reference layer, wherein the insulating layer is formed of a non-magnetic material;

[0011] A free layer is located above the insulating layer, and the free layer is formed by the two-dimensional magnetic heterojunction material-2H-VSeTe.

[0012] Optionally, the chemical formula of the two-dimensional magnetic heterojunction material is 2H-VSeTe, and each V atom in the two-dimensional magnetic heterojunction -2H-VSeTe is connected to three Se atoms and three Te atoms to form a lattice structure of a composite of a triangular prism and a hexagonal honeycomb.

[0013] Optionally, a two-dimensional magnetic heterojunction material, characterized in that the two-dimensional magnetic heterojunction -2H-VSeTe is composed of 2H-VSe 2 With 2H-VTe 2 Composition, 2H-VSe 2 The V atom is located at the geometric center, and the V atom forms coordination with the six nearest neighboring Se atoms around it to form an octahedral geometry; the 2H-VTe 2 The V atom is located at the geometric center, and the V atom is coordinated with the six nearest neighbor Te atoms around it to form an octahedral geometry.

[0014] Optionally, the unit cell structure of the 2H-VSeTe includes six V atoms, six Se atoms and six Te atoms, and the six V atoms are in the same plane, and the Se atoms and the Te atoms are evenly distributed on both sides of the plane formed by the V atoms.

[0015] Optionally, the Se atoms and the Te atoms are divided into two groups, each group includes three Se atoms and three Te atoms; in each group, the three Se atoms and the three Te atoms are respectively located on both sides of the plane formed by the V atoms.

[0016] Optionally, in the first group, the three Se atoms are located on the upper side of the plane formed by the V atoms, and the three Te atoms are located on the lower side of the plane formed by the V atoms; and in the second group, the three Se atoms are located on the lower side of the plane formed by the V atoms, and the three Te atoms are located on the upper side of the plane formed by the V atoms.

[0017] Optionally, on the side of the 2H-VSeTe structure, two Se atoms and two Te atoms are alternately arranged on both sides of the plane formed by the V atoms.

[0018] Optionally, the non-magnetic material forming the insulating layer includes: MgO, Al 2 O 3 or SiO 2 .

[0019] Another aspect of the present invention provides a method for forming a magnetic tunnel junction, characterized in that it comprises the following steps:

[0020] Providing a semiconductor substrate;

[0021] forming a reference layer on the semiconductor substrate;

[0022] forming an insulating layer on the reference layer;

[0023] A free layer is formed on the insulating layer, and the free layer is formed of the above-mentioned two-dimensional magnetic heterojunction 2H-VSeTe material.

[0024] Another aspect of the present invention provides a magnetic random access memory, characterized by any one of the magnetic tunnel junctions mentioned above.

[0025] As described above, the magnetic tunnel junction provided by the present invention has at least the following beneficial technical effects:

[0026] This invention proposes for the first time to use the two-dimensional lateral heterojunction magnetic material, 2H-VSeTe, as an innovative material choice for the free layer or reference layer of the magnetic tunnel junction (MTJ). This innovative design is not only based on the unique magnetic properties of 2H-VSeTe itself, but also achieves a significant improvement and optimization of the material's magnetic properties by applying a sophisticated control strategy to it.

[0027] Specifically, by straining and doping 2H-VSeTe, the present invention effectively improves its magnetic stability and significantly enhances the perpendicular magnetic anisotropy (PMA) of the magnetic tunnel junction. This enhancement not only helps to improve the stability and reliability of the tunneling current, thereby directly optimizing the overall performance of the storage device, but also provides a solid material foundation for achieving a more stable magnetic storage state.

[0028] In addition, the invention also emphasizes the importance of improving the voltage-controlled magnetic anisotropy (VCMA) coefficient. Introducing the two-dimensional magnetic lateral heterojunction 2H-VSeTe as a free layer into MRAM (magnetoresistive random access memory) not only significantly improves the sensitivity of the memory, making the data reading and writing process more accurate and correct, but also makes it possible to achieve a smaller MRAM cell size by optimizing the VCMA coefficient. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 The two transition metal sulfides 2H-VSe provided in this example are shown 2 / 2H-VTe 2 A schematic diagram of the structure of a top view.

[0030] Figure 2 The two transition metal sulfides 2H-VSe provided in this example are shown 2 / 2H-VTe 2 Schematic diagram of the structure of the side view.

[0031] Figure 3 A schematic diagram showing a top view of the two-dimensional magnetic heterostructure 2H-VSeTe provided in this embodiment.

[0032] Figure 4 A schematic diagram showing a side view of a two-dimensional magnetic heterostructure 2H-VSeTe provided for this embodiment.

[0033] Figure 5 Shown is a schematic structural diagram of a magnetic tunnel junction provided by this embodiment.

[0034] Figure 6 A flow chart showing a method for forming a magnetic tunnel junction is shown.

[0035] Reference numerals

[0036] 001, substrate; 002, reference layer; 003, insulating layer; 004, free layer. DETAILED DESCRIPTION

[0037] The following describes the embodiments of the present invention through specific examples, and those skilled in the art can easily understand other advantages and effects of the present invention from the contents disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and the details in this specification can also be modified or changed in various ways based on different viewpoints and applications without departing from the spirit of the present invention.

[0038] It should be noted that the illustrations provided in this embodiment only illustrate the basic concept of the present invention in a schematic manner. Although the illustrations only show components related to the present invention rather than being drawn according to the number, shape and size of components in actual implementation, the form, quantity, positional relationship and proportion of each component in actual implementation can be changed at will under the premise of realizing the technical solution of this party, and the component layout form may also be more complicated.

[0039] The theoretical calculation of the two-dimensional magnetic heterostructure material provided by the present invention adopts the commercial computing software package VASP (Vienna ab initio simulation package) developed by the University of Vienna, Austria. The VASP software package is a commonly used theoretical tool, which is developed based on density functional theory. In the calculation process, the exchange correlation energy of electrons adopts the generalized gradient approximation GGA (gengeral gradient approximation) of PBE (Perdew-Burke-Ernzerhof). The interaction between electrons and ions is described by the projected augmented wave (PAW) method. In order to avoid the interaction between adjacent cells, a certain 15 Å vacuum layer is applied in the Z direction, and the plane wave basis set cutoff energy is set to 500 eV. The K-point sampling of the Brillouin zone uses the Monkhorst-Pack scheme centered on Gamma, and the K-point grid is 5×18×1. The electron relaxation accuracy is set to 10 -6 eV, and the convergence criterion is that the force acting on each atom is less than 0.01 eV / Å.

[0040] This embodiment provides a two-dimensional magnetic heterostructure, such as Figure 1 As shown, it is a schematic diagram showing the structures of two transition metal sulfides provided in this embodiment; Figure 1 As shown, the purple balls represent V atoms, and the white balls represent Se or Te atoms: 2H-VSe 2 The V atom is located in the center and forms a coordination with the six nearest neighbor Se atoms around it, forming an octahedral geometry; 2H-VTe 2 The V atom is located at the center and forms coordination with the six nearest neighbor Te atoms around it, forming an octahedral geometry, in which the V atom is located at the center of the octahedron, while the Se and Te atoms are located at the six vertices of the octahedron.

[0041] 2H-VSe 2 The V atoms and the Se atoms form a triangular prism-hexagonal honeycomb lattice structure, the side of the triangular prism is composed of V-Se bonds, and the hexagonal honeycomb structure is formed by the connection between Se atoms; 2H-VTe 2The V atoms and Te atoms form a triangular prism-hexagonal honeycomb lattice structure. The sides of the triangular prism are composed of V-Te bonds, and the hexagonal honeycomb structure is formed by the connections between Te atoms.

[0042] like Figure 3 , which is a schematic diagram showing a top view of a two-dimensional magnetic heterostructure provided in this embodiment; Figure 4 A schematic diagram showing a side view of a two-dimensional magnetic heterostructure provided for this embodiment.

[0043] Specifically, from the structural point of view, 2H-VSe 2 With 2H-VTe 2 The 2H-VSeTe molecular structure is constructed on the same plane through chemical bonds. Each V atom is connected to three Se atoms and three Te atoms. The V atoms are in the same plane, and the Se atoms and Te atoms are distributed on both sides of the plane formed by the V atoms, forming a lattice structure of a triangular column and a hexagonal honeycomb. The side of the structure is jointly constructed by V-Se bonds and V-Te bonds, and Se atoms and Te atoms are arranged in an alternating manner up and down.

[0044] Figure 3 The dotted box shown is a top view of the primitive cell structure of the 2H-VSeTe structure; Figure 4 The dotted frame is a side view of the unit cell structure of the 2H-VSeTe structure; it can be seen from the figure that the 2H-VSeTe unit cell includes six V atoms, six Se atoms and six Te atoms, the six V atoms are in the same plane, and the Se atoms and Te atoms are evenly distributed on both sides of the plane formed by the V atoms. Specifically, the six Se atoms and the six Te atoms can be divided into two groups, each group includes three Se atoms and three Te atoms, and in the first group, the three Se atoms are located on the upper side of the plane formed by the V atoms, and the three Te atoms are located on the lower side of the plane formed by the V atoms; in the second group, the three Se atoms are located on the lower side of the plane formed by the V atoms, and the three Te atoms are located on the upper side of the plane formed by the V atoms.

[0045] The 2H-VSeTe structure provided by the present invention is subjected to a series of regulation, and the obtained data are shown in Table 1 below; first, in terms of strain regulation, the present invention applies a strain range of -6% to 6% to 2H-VSeTe. As can be seen from Table 1, it is found that the magnetic anisotropy (MCA) of 2H-VSeTe is 0.47 erg / cm² under a strain of 4%; under a strain of 5%, the magnetic anisotropy (MCA) reaches 1.91 erg / cm². This shows that moderate strain can significantly improve the MCA of 2H-VSeTe, thereby enhancing the magnetoresistance effect of MTJ. In addition, it can be seen from the data in Table 1 that in a magnetic tunnel heterojunction, when 2H-VSeTe is subjected to strain in a specific direction, the MCA changes and the magnetization direction changes. This strain regulation not only provides a new way to optimize MTJ performance, but also lays the foundation for the realization of strain-driven magnetic storage devices.

[0046] Furthermore, the carrier doping of 2H-VSeTe was adjusted from -0.6% to 0.6%. It can be seen from Table 1 that under the condition of 0.3% hole doping, the MCA is 0.14 erg / cm²; under the condition of 0.4% hole doping, the MCA is 2.62 erg / cm²; under the condition of 0.5% hole doping, the MCA is 4.71 erg / cm²; under the condition of 0.6% hole doping, the MCA is as high as 5.51erg / cm². This result not only further verifies the significant influence of strain and carrier doping on the magnetic properties of 2H-VSeTe, but also reveals the potential of achieving higher PMA by precisely controlling the carrier concentration.

[0047] In addition, the present invention also explores the effect of voltage regulation on the magnetic properties of 2H-VSeTe. As a non-contact and reversible regulation method, voltage regulation provides a new idea for the dynamic control of MTJ. Specifically, the changes in MCA of 2H-VSeTe under voltage regulation of 0 V / Å, 0.25 V / Å, and 0.5 V / Å were studied respectively. As can be seen from Table 1, at 0 V / Å, the MCA is -11.38 erg / cm²; at 0.25 V / nm, the MCA is -6.47 erg / cm²; at 0.5 V / Å, the MCA is -1.89 erg / cm². The MCA value here is negative, and the easy magnetization direction is along the plane. Although the MCA value is negative, this finding still highlights the superiority and controllability of 2H-VSeTe in magnetic properties. This result means that the magnetic properties of the magnetic tunnel junction can be significantly changed by voltage regulation, which makes it possible to achieve low-power and high-speed magnetic storage.

[0048] Table 1 Results of regulating the structure of 2H-VSeTe

[0049] Strain(%) <![CDATA[MCA erg / cm 2 ]]> q / uc <![CDATA[MCA erg / cm 2 ]]> <![CDATA[E I (V / nm)]]> <![CDATA[MCA erg / cm 2 ]]> -6 -8.40 -0.6 5.51 -5 -6.96 -0.5 4.71 -4 -13.55 -0.4 2.62 -3 -14.26 -0.3 0.14 0 -11.38 -2 -12.72 -0.2 -3.44 -1 -11.43 -0.1 -6.69 0 -10.27 0 -10.27 1 -8.71 0.1 -10.05 0.25 -6.47 2 -7.15 0.2 -9.97 3 -1.48 0.3 -9.58 4 0.47 0.4 -9.81 0.5 -1.89 5 1.91 0.5 -5.58 6 -4.34 0.6 -6.17

[0050] Figure 5 As shown, it is a schematic diagram of the structure of a magnetic tunnel junction provided by this embodiment; Figure 5 It can be seen that the magnetic tunnel junction provided in this embodiment includes a substrate 001, a reference layer 002, an insulating layer 003 and a free layer 004. The reference layer 002 is above the substrate 001, the insulating layer 003 is above the reference layer 002, and the free layer 004 is above the insulating layer 003. Generally, the material forming the substrate 001 includes silicon, silicon carbide, gallium nitride, etc., the material forming the reference layer 002 and the free layer 004 includes a ferromagnetic metal material, and the insulating layer 003 is formed of a non-magnetic material. Specifically, the reference layer 002 is formed of a ferromagnetic metal material or a material of a two-dimensional magnetic heterostructure-2H-VSeTe; the free layer 004 is formed of a two-dimensional magnetic heterojunction-2H-VSeTe material.

[0051] Specifically, the present invention also provides a method for forming a magnetic tunnel junction. Figure 6 , which is a flow chart of a method for forming a magnetic tunnel junction. Specifically, the method steps for forming a magnetic tunnel junction include: S1: providing a semiconductor substrate; S2: forming a reference layer on the semiconductor substrate; S3: forming an insulating layer on the reference layer; S4: forming a free layer on the insulating layer, wherein the free layer is formed of the above-mentioned two-dimensional magnetic heterojunction-2H-VSeTe material.

[0052] Specifically, the step of forming a reference layer on a semiconductor substrate includes: depositing a reference layer film on a substrate: depositing a reference layer film on substrate 001. Depositing a barrier layer film: depositing a barrier layer film on reference layer 002 film. As required, other films may also need to be deposited on the barrier layer, such as a free layer film, a metal oxide film, etc. In general, deposition methods include physical vapor deposition (PVD) or chemical vapor deposition (CVD) radio frequency magnetron sputtering processes and the like. Step S3 and step S4 are both commonly used process methods in the art and will not be described in detail here.

[0053] Specifically, in a magnetic tunnel heterojunction, 2H-VSeTe can be used as a free layer or a reference layer, forming a sandwich structure with an insulating layer between the free layer and the reference layer. The key to this structure lies in the magnetic coupling between the magnetic layers and the magnetoresistance effect achieved through the tunnel barrier layer. The magnetic anisotropy (MCA) and controllability of the magnetization direction of 2H-VSeTe directly determine the performance of the MTJ, such as the magnetoresistance ratio, switching speed, and stability, opening up new avenues for the application of magnetic tunnel junctions (MTJs).

[0054] In summary, the present invention verifies the magnetic properties of 2H-VSeTe, especially its perpendicular magnetic anisotropy (PMA) and voltage-controlled magnetic anisotropy (VCMA), through strain control, carrier doping control, and voltage. These findings not only provide a strong guarantee for the stability, reliability, and durability of magnetic tunnel junctions (MTJs), but also provide new ideas and methods for realizing low-power, high-speed magnetic storage devices.

[0055] This embodiment also provides a magnetic random access memory, including the above-mentioned magnetic tunnel junction.

[0056] The above embodiments are merely illustrative of the principles and effects of the present invention, and are not intended to limit the present invention. Anyone familiar with the art may modify or alter the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or alterations made by a person of ordinary skill in the art without departing from the spirit and technical concept disclosed by the present invention shall still be covered by the claims of the present invention.

Claims

1. A magnetic tunnel junction, characterized in that: include: substrate; A reference layer, located above the substrate, wherein the reference layer is formed of a ferromagnetic metal material or a two-dimensional magnetic heterojunction material - 2H-VSeTe; an insulating layer, located above the reference layer, wherein the insulating layer is formed of a non-magnetic material; A free layer is located above the insulating layer, and the free layer is formed by the two-dimensional magnetic heterojunction material-2H-VSeTe.

2. The magnetic tunnel junction according to claim 1, characterized in that: Each V atom in the two-dimensional magnetic heterojunction material - 2H-VSeTe is connected to three Se atoms and three Te atoms to form a lattice structure of a composite of a triangular prism and a hexagonal honeycomb.

3. The magnetic tunnel junction according to claim 1, characterized in that: The 2H-VSeTe is composed of 2H-VSe2 and 2H-VTe2. The V atom in 2H-VSe2 is located at the geometric center, and the V atom is coordinated with the six nearest neighbor Se atoms around it to form an octahedral geometric shape; the V atom in 2H-VTe2 is located at the geometric center, and the V atom is coordinated with the six nearest neighbor Te atoms around it to form an octahedral geometric shape.

4. The magnetic tunnel junction according to claim 1, characterized in that: The unit cell structure of the 2H-VSeTe includes six V atoms, six Se atoms and six Te atoms, and the six V atoms are in the same plane, and the Se atoms and the Te atoms are evenly distributed on both sides of the plane formed by the V atoms.

5. The magnetic tunnel junction according to claim 4, characterized in that: The Se atoms and the Te atoms are divided into two groups, each group includes three Se atoms and three Te atoms; in each group, the three Se atoms and the three Te atoms are respectively located on both sides of the plane formed by the V atoms.

6. The magnetic tunnel junction according to claim 5, characterized in that: In the first group, the three Se atoms are located on the upper side of the plane formed by the V atoms, and the three Te atoms are located on the lower side of the plane formed by the V atoms; and in the second group, the three Se atoms are located on the lower side of the plane formed by the V atoms, and the three Te atoms are located on the upper side of the plane formed by the V atoms.

7. The magnetic tunnel junction according to claim 5, characterized in that: On the side of the 2H-VSeTe structure, two Se atoms and two Te atoms are alternately arranged on both sides of the plane formed by the V atoms.

8. The magnetic tunnel junction according to claim 1, characterized in that: The non-magnetic material forming the insulating layer includes: MgO, Al2O3 or SiO2.

9. A method for forming a magnetic tunnel junction, characterized in that: The following steps are involved: Providing a semiconductor substrate; forming a reference layer on the semiconductor substrate; forming an insulating layer on the reference layer; A free layer is formed on the insulating layer, wherein the free layer is formed of the material of the two-dimensional magnetic heterojunction according to claim 1 .

10. A magnetic random access memory, characterized in that: A magnetic tunnel junction comprising any one of claims 1 to 7.

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