storage unit and memory

Abstract

The application provides a storage unit and a memory. The storage unit comprises a free layer, a tunneling barrier layer and a fixed layer which are arranged in a direction away from a substrate, the magnetization directions of the free layer and the fixed layer are perpendicular to a film plane, and the material of the fixed layer comprises a ternary alloy with a tetragonal structure. Through the application, the problem that the coercivity of the free layer of the magnetic tunnel junction and the flipping field of the reference layer cannot be effectively separated in the prior art is solved.

Description

Technical Field

[0001] This application relates to the field of memory technology, and more specifically, to a memory cell and a memory. Background Technology

[0002] Magnetoresistive random access memory (MRAM) is a non-volatile memory technology that uses the resistance changes of magnetic materials to store data. Its core principle is based on the characteristic that the resistance of a magnetic tunnel junction (MTJ) changes with its magnetic state. The MRAM mainly consists of a free layer, a fixed layer, and a tunneling barrier layer. The magnetization direction of the magnetic material in the free layer can be changed by an external magnetic field or current; the magnetization direction of the magnetic material in the fixed layer remains constant, serving as a reference layer; the tunneling barrier layer is typically made of an insulating material, allowing electrons to pass through via quantum tunneling.

[0003] Magnetoresistive random access memories (MRAMs) are classified into two structures based on their magnetization direction: in-plane magnetized MRAM (i-MRAM) and perpendicular magnetized MRAM (p-MRAM). In in-plane MRAM, the magnetization directions of the free and fixed layers of the magnetic tunnel junction are parallel to the thin film plane; in perpendicular MRAM, the magnetization directions of the free and fixed layers of the magnetic tunnel junction are perpendicular to the thin film plane.

[0004] Magnetic tunnel junctions are classified into two structures based on the location of the anchor layer: bottom-pinned and top-pinned. A bottom-pinned magnetic tunnel junction is one where the anchor layer is closer to the substrate than the free layer; a top-pinned magnetic tunnel junction is one where the free layer is closer to the substrate than the anchor layer.

[0005] Currently, in traditional top-pinned p-MRAMs, due to the special nature of the top-pinned structure, the coercivity (Hc) of the free layer of the magnetic tunnel junction cannot be effectively separated from the flip field of the reference layer, which easily leads to the rebound phenomenon of the magnetic tunnel junction, thus seriously restricting the magnetic tunnel junction from entering the product-level development and application. Summary of the Invention

[0006] The main objective of this application is to provide a storage unit and a memory to solve the problem that the coercivity of the free layer and the flip field of the reference layer in the prior art cannot be effectively separated.

[0007] To achieve the above objectives, according to one aspect of this application, a memory cell is provided, comprising a free layer, a tunneling barrier layer, and a fixed layer stacked along a direction away from the substrate, wherein the magnetization directions of the free layer and the fixed layer are perpendicular to the thin film plane, and the material of the fixed layer comprises a ternary alloy having a tetragonal crystal structure.

[0008] Optionally, the fixing layer is a multilayer thin film structure, which includes a first ferromagnetic layer, a first spacer layer and a second ferromagnetic layer stacked together. The first ferromagnetic layer is located between the tunneling barrier layer and the first spacer layer. The material of the first ferromagnetic layer and / or the second ferromagnetic layer includes a ternary alloy with a tetragonal crystal structure.

[0009] Optionally, the multilayer thin film structure further includes a first reference layer located between the tunneling barrier layer and the first ferromagnetic layer.

[0010] Optionally, the fixing layer is a multilayer thin film structure, which includes a second reference layer, a third ferromagnetic layer, a second spacer layer and a fourth ferromagnetic layer stacked together. The second reference layer is located between the tunneling barrier layer and the third ferromagnetic layer, and the material of the second reference layer includes a ternary alloy with a tetragonal crystal structure.

[0011] Optionally, the storage cell also includes a lattice matching layer located on the side of the fixed layer away from the tunneling barrier layer.

[0012] Optionally, the material of the lattice matching layer is selected from one or more of chromium, molybdenum, tungsten, magnesium fluoride, magnesium oxide, zinc oxide, titanium oxide, magnesium titanium oxide, magnesium aluminum oxide, magnesium iron oxide, zirconium nitride, and manganese nitride.

[0013] Optionally, the ternary alloy is a manganese-based alloy.

[0014] Optionally, the chemical formula of the manganese-based alloy is MnXY, where Mn is manganese, X and Y are different elements, and X and Y are independently selected from any one of magnesium, aluminum, beryllium, silicon, calcium, scandium, strontium, gallium, germanium, indium, tin and antimony.

[0015] Optionally, the memory cell may further include a spin-orbit torque layer located between the substrate and the free layer.

[0016] According to another aspect of this application, a memory is provided, including any of the above-described memory cells.

[0017] Using the technical solution of this application, a memory cell includes a free layer, a tunneling barrier layer, and a fixed layer, which are sequentially stacked along a direction away from the substrate. That is, the memory cell provided in this application has a top-pinned structure. Furthermore, the magnetization directions of the free layer and the fixed layer of the aforementioned memory cell are perpendicular to the thin film plane, which also means that the free layer and the fixed layer have a perpendicular magnetization direction. It is understood that an interface perpendicular magnetic anisotropy (interface PMA) can be generated at the interface between the tunneling barrier layer and the fixed layer, and this interface PMA helps the fixed top maintain a stable magnetization direction. Based on this, the fixed layer material of this application includes a ternary alloy with a tetragonal crystal structure. Since the lattice constant *c* of the tetragonal crystal cell in the vertical direction differs from the lattice constant *a* in the horizontal direction (i.e., *a* ≠ *c*), the ternary alloy material with a tetragonal crystal structure can disrupt the centrosymmetry of the fixed layer material in three-dimensional space. This is particularly beneficial for the spin-orbit coupling effect in the vertical direction, manifested as enhanced vertical magnetic anisotropy, and can provide higher magnetic anisotropy energy (Ku). This also means that the fixed layer has a stronger ability to resist changes in magnetization direction, making the magnetic moment of the fixed layer more stable in the vertical direction, requiring a larger magnetic field or current to cause a flip, while the coercivity of the free layer remains relatively low, thus effectively widening the gap between the flip field of the fixed layer and the coercivity of the free layer. Therefore, this application solves the problem in the prior art that the coercivity of the free layer and the flip field of the reference layer in magnetic tunnel junctions cannot be effectively separated, thereby ensuring that the magnetization state of the fixed layer remains unchanged throughout the entire lifespan of the memory cell, improving the reliability of the memory cell. Furthermore, ternary alloys can form ordered phases, which better match other materials in the memory cell (such as tunneling barrier layers and free layers), thereby optimizing the overall performance of the memory cell. Moreover, the ordered phase transition temperature of ternary alloys matches the temperature range of CMOS manufacturing processes. This means that ternary alloys are compatible with the entire manufacturing process of memory cells (such as high-temperature annealing and etching) without the need for additional low- or high-temperature process steps, thus ensuring manufacturing process compatibility and product consistency. Attached Figure Description

[0018] The accompanying drawings, which form part of this application, are used to provide a further understanding of this application. The illustrative embodiments and descriptions of this application are used to explain this application and do not constitute an undue limitation of this application. In the drawings:

[0019] Figure 1 A cross-sectional structural schematic diagram of a storage cell provided according to Embodiment 1 of this application is shown;

[0020] Figure 2 A cross-sectional structural schematic diagram of a storage cell provided according to Embodiment 2 of this application is shown;

[0021] Figure 3 A cross-sectional structural schematic diagram of a storage cell provided according to Embodiment 3 of this application is shown;

[0022] Figure 4 A cross-sectional structural schematic diagram of a storage cell provided according to Embodiment 1 of this application is shown.

[0023] The above figures include the following reference numerals:

[0024] 10. Spin-orbit torque layer; 20. Free layer; 30. Tunneling barrier layer; 40. Fixed layer; 401. First reference layer; 501. First ferromagnetic layer; 601. First spacer layer; 701. Second ferromagnetic layer; 402. Second reference layer; 502. Third ferromagnetic layer; 602. Second spacer layer; 702. Fourth ferromagnetic layer; 80. Lattice matching layer; 90. Capping layer. Detailed Implementation

[0025] It should be noted that the following detailed descriptions are illustrative and intended to provide further explanation of this 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 art to which this application pertains.

[0026] It should be noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the exemplary embodiments according to this application. As used herein, the singular form is intended to include the plural form as well, unless the context clearly indicates otherwise. Furthermore, it should be understood that when the terms "comprising" and / or "including" are used in this specification, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof.

[0027] It should be noted that the terms "first," "second," etc., in the specification, claims, and accompanying drawings of this invention are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate for the embodiments of the invention described herein. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover non-exclusive inclusion; for example, a process, method, system, product, or apparatus that comprises a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to such processes, methods, products, or apparatus.

[0028] 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 may be directly on the other element, or there may be an intermediate element present. Furthermore, in the specification and claims, when an element is described as being "connected" to another element, the element may be "directly connected" to the other element, or "connected" to the other element via a third element.

[0029] For ease of description, the following explains some of the nouns or terms used in the embodiments of this application:

[0030] The coercivity (Hc) of the free layer refers to the minimum magnetic field strength required for its magnetization state to reverse, while the reversal field of the fixed layer is the force required for its magnetization direction to remain unchanged until the applied magnetic field exceeds this threshold. In existing technologies, these two are often difficult to separate effectively, which can easily affect the magnetization state of the fixed layer during the writing process, thus affecting the stability of the memory cell.

[0031] As described in the background section, in traditional top-pinned p-MRAMs, due to the unique nature of the top-pinning structure, the coercivity (Hc) of the free layer of the magnetic tunnel junction cannot be effectively separated from the flip field of the reference layer. This easily leads to a bounce phenomenon in the magnetic tunnel junction, severely restricting its application in product-level development. To address the problem of the inability to effectively separate the coercivity of the free layer from the flip field of the reference layer in the prior art, embodiments of this application provide a storage unit and a memory.

[0032] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention.

[0033] According to one aspect of this application, such as Figure 1 , Figure 2 , Figure 3 and Figure 4 As shown, a memory cell is provided, comprising a free layer 20, a tunneling barrier layer 30, and a fixed layer 40 stacked along a direction away from the substrate. The magnetization directions of the free layer 20 and the fixed layer 40 are perpendicular to the thin film plane, and the material of the fixed layer 40 comprises a ternary alloy having a tetragonal crystal structure.

[0034] Understandably, when reading the state of the aforementioned memory cell, the magnetization state of the fixed layer 40 can be used as a known reference for comparison with the unknown state of the free layer 20, thus the fixed layer 40 also serves as a reference layer for the memory cell. For example, if the magnetization directions of the free layer 20 and the fixed layer 40 are aligned, the memory cell (such as a magnetic tunnel junction, MTJ) is in a low-resistance state (typically representing binary 0); if the magnetization directions of the free layer 20 and the fixed layer 40 are opposite, the memory cell (such as a magnetic tunnel junction, MTJ) is in a high-resistance state (typically representing binary 1).

[0035] The aforementioned free layer 20, tunneling barrier layer 30, and fixed layer 40 are stacked in a direction away from the substrate, such that the fixed layer 40 can be located at the top of the entire memory cell stack structure, while the free layer 20 can be located at the bottom of the entire memory cell stack structure. This layout is called a top-pinned structure. Memory cells with a top-pinned structure are beneficial for integration with CMOS front-end circuitry, allowing devices to be stacked and increasing chip storage density.

[0036] The materials of the free layer 20 and the fixed layer 40 can be ferromagnetic materials, and the material of the tunneling barrier layer 30 can be an insulating material. It is understood that the tunneling barrier layer 30, located between the free layer 20 and the fixed layer 40, not only maintains the electrical insulation between the free layer 20 and the fixed layer 40, but also influences the magnetic tunneling resistance (TMR) effect through its thickness and material properties, thereby improving the read sensitivity of the memory cell.

[0037] The aforementioned thin film plane refers to the plane in which the free layer 20 and the fixed layer 40 extend horizontally. The magnetization directions of the free layer 20 and the fixed layer 40 are perpendicular to the thin film plane, meaning that the magnetic moments of the free layer 20 and the fixed layer 40 point towards or away from the substrate, i.e., along the z-axis direction perpendicular to the thin film plane.

[0038] Specifically, the material of the free layer 20 may be any one or more of the following, including but not limited to cobalt-iron-boron alloy (CoFeB), iron-boron alloy (FeB), cobalt-iron alloy (CoFe), and iron (Fe).

[0039] Specifically, the material of the tunneling barrier layer 30 may be selected from at least one of the following materials: (MgO), aluminum oxide (Al2O3), hafnium dioxide (HfO2), magnesium aluminum oxide (MgAlO), copper oxide (CuO), and copper (Cu).

[0040] Specifically, the aforementioned ternary alloy with a tetragonal crystal structure can be a manganese-based alloy (MnXY), where Mn is manganese, X and Y are different elements, and X and Y are independently selected from any one of magnesium, aluminum, beryllium, silicon, calcium, scandium, strontium, gallium, germanium, indium, tin and antimony.

[0041] Since manganese-based alloys have a low saturation magnetization (Ms), when the material of the fixed layer 40 includes a ternary alloy with a tetragonal crystal structure and the ternary alloy is a manganese-based alloy, the manganese-based alloy helps to reduce the stray field influence of the fixed layer 40 on the free layer 20, making the magnetization state of the free layer 20 easier to control without interference from the fixed layer 40, thereby improving the read / write performance and data stability of the storage cell.

[0042] In some alternative embodiments, the chemical formula of the above-mentioned manganese-based alloy, in addition to MnXY, can also be Mn 1+ a X 1+b Y 1+c In this alloy, the atomic percentages of elements X and Y relative to Mn can fluctuate by up to 20% above or below their theoretical values. To reiterate, given the theoretical ratio of X, Y, and Mn as 33.3% each (X, Y, and Mn), the actual preparation process can adaptively adjust the ratios of X and Y to vary within the ranges of 15%-35% and 20%-40%, respectively, while ensuring that the Mn content is adjusted accordingly to maintain a total atomic percentage of 100%.

[0043] In some alternative embodiments, the thickness of the material layer having the above-described MnXY alloy ranges from 1 nanometer to 15 nanometers.

[0044] Using the technical solution of this application, a memory cell includes a free layer 20, a tunneling barrier layer 30, and a fixed layer 40, wherein the free layer 20, the tunneling barrier layer 30, and the fixed layer 40 are sequentially stacked along a direction away from the substrate. That is, the memory cell provided by this application has a top-pinned structure. Furthermore, the magnetization direction of the free layer 20 and the fixed layer 40 of the above-mentioned memory cell is perpendicular to the thin film plane, which also means that the free layer 20 and the fixed layer 40 have a perpendicular magnetization direction. It is understood that an interface perpendicular magnetic anisotropy (interface PMA) can be generated at the interface between the tunneling barrier layer 30 and the fixed layer 40, and this interface PMA helps the fixed top maintain a stable magnetization direction. Based on this, the material of the fixed layer 40 in this application includes a ternary alloy with a tetragonal crystal structure. Since the lattice constant c in the vertical direction of the tetragonal crystal cell is different from the lattice constant a in the horizontal direction (i.e., a≠c), the ternary alloy material with a tetragonal crystal structure can disrupt the centrosymmetry of the fixed layer 40 material in three-dimensional space. This is particularly beneficial to the spin-orbit coupling effect in the vertical direction, manifested as enhanced vertical magnetic anisotropy, which can provide higher magnetic anisotropy energy (high Ku Bulk PMA). This also means that the fixed layer 40 has a stronger ability to resist changes in magnetization direction, making the magnetic moment of the fixed layer 40 more stable in the vertical direction, requiring a larger magnetic field or current to cause a flip, while the coercivity of the free layer 20 remains relatively low, thus effectively widening the gap between the flip field of the fixed layer 40 and the coercivity of the free layer 20. Therefore, this application solves the problem in the prior art where the coercivity of the free layer 20 of a magnetic tunnel junction cannot be effectively separated from the flip field of the reference layer, thereby ensuring that the magnetization state of the fixed layer 40 remains unchanged throughout the entire lifespan of the memory cell, improving the reliability of the memory cell. Furthermore, ternary alloys can form ordered phases (such as... Figures 1 to 4 The arrangement of MnXY (as shown in the dashed box) allows for better matching with other materials in the memory cell (such as the tunneling barrier layer 30 and the free layer 20), thereby optimizing the overall performance of the memory cell. Furthermore, the ordered phase transition temperature of the ternary alloy matches the temperature range of CMOS manufacturing processes. This means that the ternary alloy is compatible with the entire manufacturing process of the memory cell (such as high-temperature annealing and etching) without the need for additional low-temperature or high-temperature process steps, thus ensuring the manufacturing process compatibility and product consistency of the memory cell.

[0045] Optionally, the fixing layer of the above-mentioned storage cell can be a single-layer thin film structure or a multi-layer thin film structure.

[0046] In some embodiments, when the aforementioned fixed layer is a single-layer thin film structure, the storage cell may include a free layer, a tunneling barrier layer, and a reference layer stacked along the direction away from the substrate, wherein the material of the reference layer includes a ternary alloy having a tetragonal crystal structure.

[0047] Specifically, the material of the reference layer may include the aforementioned MnXY alloy.

[0048] In some implementations, such as Figures 1 to 4 As shown, when the aforementioned fixed layer 40 is a multilayer thin film structure, the multilayer thin film structure can be a synthetic antiferromagnetic (SAF) structure, and the material of at least one ferromagnetic layer in the synthetic antiferromagnetic structure includes a ternary alloy with a tetragonal crystal system; or, the multilayer thin film structure can include a reference layer and a synthetic antiferromagnetic structure, and the material of the reference layer includes a ternary alloy with a tetragonal crystal system or the material of at least one ferromagnetic layer in the synthetic antiferromagnetic structure includes a ternary alloy with a tetragonal crystal system.

[0049] In some alternative implementations, such as Figure 1 and Figure 2 As shown, the multilayer thin film structure includes a first ferromagnetic layer 501, a first spacer layer 601 and a second ferromagnetic layer 701 stacked together. The first ferromagnetic layer 501 is located between the tunneling barrier layer 30 and the first spacer layer 601. The material of the first ferromagnetic layer 501 and / or the second ferromagnetic layer 701 includes a ternary alloy with a tetragonal crystal structure.

[0050] Specifically, the first spacer layer 601 is an antiferromagnetic spacer layer, and the material of the first spacer layer 601 can be selected from any one or more of ruthenium (Ru), iridium (Ir), and rhodium (Rh). The first spacer layer 601 forms an antiferromagnetic coupling between the second ferromagnetic layer 701 and the first ferromagnetic layer 501 and effectively blocks element diffusion at high temperatures.

[0051] It is understandable that, based on the first ferromagnetic layer 501, the first spacer layer 601, and the second ferromagnetic layer 701 forming a synthetic antiferromagnetic structure, the first ferromagnetic layer 501 and / or the second ferromagnetic layer 701, as part of the synthetic antiferromagnetic structure, can significantly enhance the stability of the entire synthetic antiferromagnetic structure by including ternary alloys with a tetragonal crystal structure in the materials of the first ferromagnetic layer 501 and / or the second ferromagnetic layer 701. This allows the synthetic antiferromagnetic structure to maintain a more stable anti-parallel coupling state, thereby ensuring the high exchange coupling field (Hex) of the synthetic antiferromagnetic structure. This solves the problem in the prior art that the coercivity of the free layer 20 of the magnetic tunnel junction cannot be effectively separated from the flip field of the reference layer.

[0052] In the above embodiments, the materials of the first ferromagnetic layer 501 and / or the second ferromagnetic layer 701 in the fixed layer 40 include a ternary alloy with a tetragonal crystal structure, thereby solving the problem in the prior art that the coercivity of the free layer 20 of the magnetic tunnel junction cannot be effectively separated from the flip field of the reference layer. Furthermore, by adding an antiferromagnetic spacer layer between the first ferromagnetic layer 501 and the second ferromagnetic layer 701, antiferromagnetic coupling can be established between the first ferromagnetic layer 501 and the second ferromagnetic layer 701, thereby forming a synthetic antiferromagnetic (SAF) structure. This synthetic antiferromagnetic (SAF) structure allows the magnetization directions of the first ferromagnetic layer 501 and the second ferromagnetic layer 701 to naturally tend towards opposite directions under conditions without an external magnetic field. When an external magnetic field attempts to reverse the magnetic moment of one of the ferromagnetic layers (such as the first ferromagnetic layer 501), due to the anti-coupling of the magnetic moments of the two ferromagnetic layers (the first ferromagnetic layer 501 and the second ferromagnetic layer 701), the magnetic moment of the other ferromagnetic layer (such as the second ferromagnetic layer 701) will also experience an internal magnetic field opposite to the direction of the external magnetic field. To reverse the two ferromagnetic layers (the first ferromagnetic layer 501 and the second ferromagnetic layer 701) simultaneously, the energy barrier generated by the antiferromagnetic coupling needs to be overcome. This energy barrier increases the minimum field strength required for the external magnetic field to reverse the magnetization state in the SAF structure (i.e., the fixed layer 40), which also means that the reversal field of the fixed layer 40 (reference layer) is enhanced. Thus, while the coercivity of the free layer 20 remains relatively low, the gap between the reversal field of the fixed layer 40 and the coercivity of the free layer 20 is further widened, further improving the success rate of effectively separating the coercivity of the free layer 20 and the reversal field of the reference layer in the magnetic tunnel junction.

[0053] In some optional embodiments, where the material of the first ferromagnetic layer includes a ternary alloy with a tetragonal crystal structure and the material of the second ferromagnetic layer does not include a ternary alloy with a tetragonal crystal structure, the material of the first ferromagnetic layer may include the aforementioned MnXY alloy, and the material of the second ferromagnetic layer is selected from any one or more of cobalt-iron-boron alloy (CoFeB), iron-boron alloy (FeB), cobalt-iron alloy (CoFe), iron (Fe), Co / Pt multilayer film, Co / Pd multilayer film, and Co / Ni multilayer film.

[0054] In some alternative implementations, such as Figure 2As shown, when the material of the first ferromagnetic layer 501 does not include a ternary alloy with a tetragonal crystal structure, and the material of the second ferromagnetic layer 701 includes a ternary alloy with a tetragonal crystal structure, the material of the first ferromagnetic layer 501 is selected from any one or more of cobalt-iron-boron alloy (CoFeB), iron-boron alloy (FeB), cobalt-iron alloy (CoFe), iron (Fe), Co / Pt multilayer film, Co / Pd multilayer film, and Co / Ni multilayer film. The material of the second ferromagnetic layer 701 may include the aforementioned MnXY alloy. For example, the aforementioned MnXY alloy is manganese-gallium alloyed germanium (MnGaGe).

[0055] In some alternative implementations, such as Figure 1 and Figure 3 As shown, when both the materials of the first ferromagnetic layer 501 and the second ferromagnetic layer 701 comprise a ternary alloy with a tetragonal crystal structure, the materials of both the first ferromagnetic layer 501 and the second ferromagnetic layer 701 can include the aforementioned MnXY alloy. For example, the aforementioned MnXY alloy is manganese-magnesium alloyed germanium (MnMgGe) or manganese-aluminum alloyed germanium (MnAlGe).

[0056] Furthermore, in some alternative implementations, such as Figure 3 As shown, in the case where the multilayer thin film structure includes the first ferromagnetic layer 501, the first spacer layer 601, and the second ferromagnetic layer 701, the multilayer thin film structure further includes a first reference layer 401, which is located between the tunneling barrier layer 30 and the first ferromagnetic layer 501. It is understood that the reference layer includes the first reference layer 401, the synthetic antiferromagnetic structure includes the first ferromagnetic layer 501, the first spacer layer 601, and the second ferromagnetic layer 701, and the material of the first ferromagnetic layer 501 and / or the second ferromagnetic layer 701 includes the aforementioned MnXY alloy.

[0057] Specifically, the material of the first reference layer 401 can be selected from any one or more of the following: cobalt-iron-boron alloy (CoFeB), iron-boron alloy (FeB), cobalt-iron alloy (CoFe), iron (Fe), Co / Pt multilayer film, Co / Pd multilayer film, and Co / Ni multilayer film. The surface characteristics of the first reference layer 401 (such as lattice orientation and surface energy) can guide the growth of the material of the first ferromagnetic layer 501, thereby providing a suitable growth template for the adjacent first ferromagnetic layer 501. Furthermore, when the material of the first ferromagnetic layer 501 includes a ternary alloy with a tetragonal crystal structure, the first ferromagnetic layer 501 can form an ordered and continuous thin film.

[0058] It is understood that when the first reference layer 401 with the above-mentioned material is in contact with the tunneling barrier layer 30, an interfacial magnetic anisotropy (interfacial PMA) can be generated at the interface between the first reference layer 401 and the tunneling barrier layer 30. Thus, the first reference layer 401 can provide a stable magnetization direction with a high rate of change of resistivity (TMR), and the vertical orientation of the magnetic moment can remain unchanged even under the influence of external environment (such as temperature change, external magnetic field).

[0059] Furthermore, since the first reference layer 401 exhibits high vertical magnetic anisotropy, these materials have good spin injection performance, which can improve the write efficiency and power consumption of SOT-MRAM after applying the memory cell with the first reference layer 401 to SOT-MRAM.

[0060] In the above embodiments, when the first reference layer 401 and the synthetic antiferromagnetic (SAF, first ferromagnetic layer 501, first spacer layer 601 and second ferromagnetic layer 701) structure together constitute the fixed layer 40 of the memory cell, the high interface PMA of the first reference layer 401 ensures the stability of its own magnetization direction, while the high exchange coupling field strength (Hex) of the synthetic antiferromagnetic (SAF) structure enhances the overall resistance of the fixed layer 40 to magnetization reversal. Thus, the stability of the magnetization direction of the fixed layer 40 comes from the superposition of the interface effect of the PMA and the antiferromagnetic coupling effect of the Hex. Based on this, the synergistic effect of the first reference layer 401 and the synthetic antiferromagnetic structure further enhances the overall resistance of the fixed layer 40 to magnetization reversal. While keeping the coercivity of the free layer 20 relatively low, it further widens the gap between the reversal field of the fixed layer 40 and the coercivity of the free layer 20, achieving the beneficial effect of further improving the success rate of effectively separating the coercivity of the free layer 20 and the reversal field of the reference layer in the magnetic tunnel junction.

[0061] In other alternative implementations, such as Figure 4 As shown, the fixing layer 40 is a multilayer thin film structure, which includes a second reference layer 402, a third ferromagnetic layer 502, a second spacer layer 602, and a fourth ferromagnetic layer 702 stacked together. The second reference layer 402 is located between the tunneling barrier layer 30 and the third ferromagnetic layer 502, and the material of the second reference layer 402 includes a ternary alloy with a tetragonal crystal structure. It is understood that the aforementioned reference layer includes the second reference layer 402, and the aforementioned synthetic antiferromagnetic structure includes the third ferromagnetic layer 502, the second spacer layer 602, and the fourth ferromagnetic layer 702.

[0062] Specifically, the materials of the third ferromagnetic layer 502 and the fourth ferromagnetic layer 702 can be independently selected from any one or more of the following: cobalt-iron-boron alloy (CoFeB), iron-boron alloy (FeB), cobalt-iron alloy (CoFe), iron (Fe), Co / Pt multilayer film, Co / Pd multilayer film, and Co / Ni multilayer film.

[0063] Specifically, the material of the second spacer layer 602 may include, but is not limited to, any one or more of ruthenium (Ru), iridium (Ir), and rhodium (Rh).

[0064] Specifically, the material of the second reference layer 402 may include the aforementioned MnXY alloy. For example, the aforementioned MnXY alloy is manganese-silicon germanium alloy (MnSiGe).

[0065] Understandably, ternary alloys with a tetragonal crystal structure exhibit high perpendicular magnetic anisotropy, meaning that the magnetic moment is more stable in the direction perpendicular to the thin film plane. By using this material in the second reference layer 402, the perpendicular magnetic anisotropy of the fixed layer 40, including the second reference layer 402, can be directly enhanced, thereby solving the problem in the prior art where the coercivity of the free layer 20 of the magnetic tunnel junction cannot be effectively separated from the flip field of the reference layer.

[0066] In the above embodiment, the third ferromagnetic layer 502, the second spacer layer 602, and the fourth ferromagnetic layer 702 constitute a synthetic antiferromagnetic structure. The third ferromagnetic layer 502 and the fourth ferromagnetic layer 702 are antiferromagnetically coupled through a second spacer layer 602, so that the synthetic antiferromagnetic structure maintains a stable magnetic state with opposite magnetization directions in the absence of an external magnetic field. The second reference layer 402 and the synthetic antiferromagnetic structure are both part of the fixed layer 40. By participating in the synthetic antiferromagnetic structure, the high perpendicular magnetic anisotropy of the second reference layer 402 can further enhance the perpendicular magnetic anisotropy of the synthetic antiferromagnetic structure, further strengthening the overall perpendicular magnetization tendency of the fixed layer 40. Thus, while keeping the coercivity of the free layer 20 relatively low, the gap between the flip field of the fixed layer 40 and the coercivity of the free layer 20 is further widened, further improving the success rate of effectively separating the coercivity of the free layer 20 and the flip field of the reference layer in the magnetic tunnel junction.

[0067] In some alternative implementations, such as Figures 1 to 4 As shown, the presence of the lattice matching layer 80 enables the fixed layer 40 to form an ordered phase at low temperatures. Therefore, in order to further enable the fixed layer 40 to form an ordered phase at a lower temperature, the memory cell also includes a lattice matching layer 80, which is located on the side of the fixed layer 40 away from the tunneling barrier layer 30.

[0068] Specifically, the material of the lattice matching layer 80 can be selected from chromium (Cr), molybdenum (Mo), tungsten (W), magnesium fluoride (MgF), magnesium oxide (MgO), zinc oxide (ZnO), titanium oxide (TiO), and magnesium titanium oxide (MgTiO). x ), magnesium aluminum oxide (MgAlO) x ), magnesium iron oxide (MgFeO) x One or more of zirconium nitride (ZrN) and manganese nitride (MnN).

[0069] In the above embodiments, the material of the lattice matching layer 80 has a specific crystal structure and lattice constant. At the contact interface between the fixed layer 40 and the lattice matching layer 80, the lattice matching layer 80 guides the atomic arrangement of the material of the fixed layer 40, causing the atomic arrangement of the fixed layer 40 to form a specific lattice structure, such as the tetragonal crystal system structure described above.

[0070] In some alternative implementations, such as Figures 1 to 4 As shown, in order to reduce the current density required by the device during the write operation and significantly reduce the power consumption of the device, the memory cell also includes a spin-orbit torque layer 10, which is located between the substrate and the free layer 20.

[0071] Specifically, the material of the spin orbital torque layer 10 may be any one or more of tungsten (W), tantalum (Ta), platinum (Pt), and bismuth selenide (BiSe).

[0072] In the above embodiment, the presence of the spin-orbit torque layer 10 allows the magnetic moment of the magnetic free layer 20 to be flipped by the transverse spin current generated in the non-magnetic heavy metal layer (spin-orbit torque layer 10) within the memory cell. This mechanism can reduce the current density and energy consumption required for writing.

[0073] In some alternative implementations, such as Figures 1 to 4 As shown, the memory cell further includes a cover layer 90, which is located on the side of the fixed layer 40 away from the free layer 20. Furthermore, when the memory cell also includes the lattice matching layer 80, the lattice matching layer 80 is located between the fixed layer 40 and the cover layer 90.

[0074] For example, the material of the aforementioned cover layer 90 may be one or more of magnesium oxide (MgO), aluminum oxide (Al2O3), hafnium dioxide (HfO2), magnesium aluminum oxide (MgAlO), copper oxide (CuO), ruthenium (Ru), tantalum (Ta), molybdenum (Mo), and tungsten (W).

[0075] It should be noted that the aforementioned memory cell can be a magnetic tunnel junction (MTJ).

[0076] The following embodiments further illustrate a storage unit and its fabrication process according to this application.

[0077] Example 1

[0078] A storage unit, such as Figure 1 As shown, the structure includes a spin-orbit torque layer 10, a free layer 20, a tunneling barrier layer 30, a first ferromagnetic layer 501, a first spacer layer 601, a second ferromagnetic layer 701, a lattice matching layer 80, and a capping layer 90, all sequentially stacked. The first ferromagnetic layer 501 is made of iron-boron alloy (FeB), and the second ferromagnetic layer 701 is made of manganese-gallium alloy germanium (MnGaGe).

[0079] In this embodiment, after forming the spin-orbit torque layer 10, the free layer 20, and the tunneling barrier layer 30, a first ferromagnetic layer 501 (interface PMA), a first spacer layer 601, and a second ferromagnetic layer 701 (bulk PMA) are sequentially deposited on the side of the tunneling barrier layer 30 away from the free layer 20. Then, a lattice-matching layer 80 is deposited on the side of the second ferromagnetic layer 701 away from the first spacer layer 601. The aforementioned memory cells are post-annealed (≤400℃) to achieve ordered phase formation at a lower temperature, ensuring compatibility with front-end CMOS processes.

[0080] Example 2

[0081] A storage unit, such as Figure 2 As shown, the structure includes a spin-orbit torque layer 10, a free layer 20, a tunneling barrier layer 30, a first ferromagnetic layer 501, a first spacer layer 601, a second ferromagnetic layer 701, a lattice matching layer 80, and a capping layer 90, all sequentially stacked. The first ferromagnetic layer 501 and the second ferromagnetic layer 701 are both made of manganese-magnesium alloyed germanium (MnMgGe), and the lattice matching layer 80 is made of magnesium aluminum oxide (MgAlO). x ).

[0082] In this embodiment, after forming the spin-orbit torque layer 10, the free layer 20, and the tunneling barrier layer 30, a first ferromagnetic layer 501 (Bulk PMA), a first spacer layer 601, and a second ferromagnetic layer 701 (Bulk PMA) are sequentially deposited on the side of the tunneling barrier layer 30 away from the free layer 20. Then, a lattice-matching layer 80 is deposited on the side of the second ferromagnetic layer 701 away from the first spacer layer 601. The aforementioned memory cells are post-annealed (≤400℃) to achieve ordered phase formation at a lower temperature, ensuring compatibility with front-end CMOS processes.

[0083] Example 3

[0084] A storage unit, such as Figure 3As shown, the structure includes a spin-orbit torque layer 10, a free layer 20, a tunneling barrier layer 30, a first reference layer 401, a first ferromagnetic layer 501, a first spacer layer 601, a second ferromagnetic layer 701, a lattice matching layer 80, and a capping layer 90, all stacked sequentially. The first reference layer 401 is made of iron-boron alloy (FeB), the first ferromagnetic layer 501 and the second ferromagnetic layer 701 are both made of manganese-aluminum alloy germanium (MnAlGe), and the lattice matching layer 80 is made of magnesium titanium oxide (MgTiO). x ).

[0085] In this embodiment, after forming the spin-orbit torque layer 10, the free layer 20, and the tunneling barrier layer 30, a first reference layer 401 (interface PMA) is first deposited on the side of the tunneling barrier layer 30 away from the free layer 20. Then, a first ferromagnetic layer 501 (Bulk PMA), a first spacer layer 601, and a second ferromagnetic layer 701 (Bulk PMA) are sequentially deposited on the side of the first reference layer 401 away from the tunneling barrier layer 30. Finally, a lattice-matching layer 80 is deposited on the side of the second ferromagnetic layer 701 away from the first spacer layer 601. The aforementioned memory cells are post-annealed (≤400°C) to achieve ordered phase formation at a lower temperature, ensuring compatibility with front-end CMOS processes.

[0086] Example 4

[0087] A storage unit, such as Figure 4 As shown, the structure includes a spin-orbit torque layer 10, a free layer 20, a tunneling barrier layer 30, a second reference layer 402, a third ferromagnetic layer 502, a second spacer layer 602, a fourth ferromagnetic layer 702, and a capping layer 90, all stacked sequentially. The second reference layer 402 is made of manganese-silicon germanium alloy (MnSiGe), while the third ferromagnetic layer 502 and the fourth magnetic layer are both made of iron-boron alloy (FeB).

[0088] In this embodiment, after forming the spin-orbit torque layer 10, the free layer 20, and the tunneling barrier layer 30, a second reference layer 402 (Bulk PMA) is first deposited on the side of the tunneling barrier layer 30 away from the free layer 20. Then, a first ferromagnetic layer 501, a first spacer layer 601, and a second ferromagnetic layer 701 are sequentially deposited on the side of the first reference layer 401 away from the tunneling barrier layer 30. Finally, a lattice-matching layer 80 is deposited on the side of the second ferromagnetic layer 701 away from the first spacer layer 601. The memory cells are post-annealed (≤400°C) to achieve ordered phase formation at a lower temperature, ensuring compatibility with front-end CMOS processes.

[0089] According to another aspect of this application, a memory is also provided, which includes any of the memory cells described above.

[0090] As can be seen from the above description, the embodiments of the present invention achieve the following technical effects:

[0091] Using the technical solution of this application, a memory cell includes a free layer, a tunneling barrier layer, and a fixed layer, which are sequentially stacked along a direction away from the substrate. That is, the memory cell provided in this application has a top-pinned structure. Furthermore, the magnetization directions of the free layer and the fixed layer of the aforementioned memory cell are perpendicular to the thin film plane, which also means that the free layer and the fixed layer have a perpendicular magnetization direction. It is understood that an interface perpendicular magnetic anisotropy (interface PMA) can be generated at the interface between the tunneling barrier layer and the fixed layer, and this interface PMA helps the fixed top maintain a stable magnetization direction. Based on this, the fixed layer material of this application includes a ternary alloy with a tetragonal crystal structure. Since the lattice constant *c* of the tetragonal crystal cell in the vertical direction differs from the lattice constant *a* in the horizontal direction (i.e., *a* ≠ *c*), the ternary alloy material with a tetragonal crystal structure can disrupt the centrosymmetry of the fixed layer material in three-dimensional space. This is particularly beneficial for the spin-orbit coupling effect in the vertical direction, manifested as enhanced vertical magnetic anisotropy, and can provide higher magnetic anisotropy energy (Ku). This also means that the fixed layer has a stronger ability to resist changes in magnetization direction, making the magnetic moment of the fixed layer more stable in the vertical direction, requiring a larger magnetic field or current to cause a flip, while the coercivity of the free layer remains relatively low, thus effectively widening the gap between the flip field of the fixed layer and the coercivity of the free layer. Therefore, this application solves the problem in the prior art that the coercivity of the free layer and the flip field of the reference layer in magnetic tunnel junctions cannot be effectively separated, thereby ensuring that the magnetization state of the fixed layer remains unchanged throughout the entire lifespan of the memory cell, improving the reliability of the memory cell. Furthermore, ternary alloys can form ordered phases, which better match other materials in the memory cell (such as tunneling barrier layers and free layers), thereby optimizing the overall performance of the memory cell. Moreover, the ordered phase transition temperature of ternary alloys matches the temperature range of CMOS manufacturing processes. This means that ternary alloys are compatible with the entire manufacturing process of memory cells (such as high-temperature annealing and etching) without the need for additional low- or high-temperature process steps, thus ensuring manufacturing process compatibility and product consistency.

[0092] The above description is merely a preferred embodiment of this application and is not intended to limit this application. Various modifications and variations can be made to this application by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. A storage unit, characterized in that, The storage cell includes a free layer, a tunneling barrier layer, and a fixed layer stacked in a direction away from the substrate. The magnetization directions of the free layer and the fixed layer are perpendicular to the thin film plane, and the material of the fixed layer includes a ternary alloy with a tetragonal crystal structure.

2. The storage unit according to claim 1, characterized in that, The fixing layer is a multilayer thin film structure, which includes a first ferromagnetic layer, a first spacer layer and a second ferromagnetic layer stacked together. The first ferromagnetic layer is located between the tunneling barrier layer and the first spacer layer. The material of the first ferromagnetic layer and / or the second ferromagnetic layer includes a ternary alloy with a tetragonal crystal structure.

3. The storage unit according to claim 2, characterized in that, The multilayer thin film structure further includes a first reference layer, which is located between the tunneling barrier layer and the first ferromagnetic layer.

4. The storage unit according to claim 1, characterized in that, The fixing layer is a multilayer thin film structure, which includes a second reference layer, a third ferromagnetic layer, a second spacer layer and a fourth ferromagnetic layer stacked together. The second reference layer is located between the tunneling barrier layer and the third ferromagnetic layer. The material of the second reference layer includes a ternary alloy with a tetragonal crystal structure.

5. The storage cell according to any one of claims 1 to 4, characterized in that, The storage unit further includes a lattice matching layer located on the side of the fixed layer away from the tunneling barrier layer.

6. The storage unit according to claim 5, characterized in that, The material of the lattice matching layer is selected from one or more of chromium, molybdenum, tungsten, magnesium fluoride, magnesium oxide, zinc oxide, titanium oxide, magnesium titanium oxide, magnesium aluminum oxide, magnesium iron oxide, zirconium nitride, and manganese nitride.

7. The storage cell according to any one of claims 1 to 4, characterized in that, The ternary alloy is a manganese-based alloy.

8. The storage unit according to claim 7, characterized in that, The chemical formula of the manganese-based alloy is MnXY, wherein Mn is manganese, X and Y are different elements, and X and Y are independently selected from any one of magnesium, aluminum, beryllium, silicon, calcium, scandium, strontium, gallium, germanium, indium, tin and antimony.

9. The storage cell according to any one of claims 1 to 4, characterized in that, The storage cell further includes a spin-orbit torque layer located between the substrate and the free layer.

10. A memory, characterized in that, It includes the storage unit as described in any one of claims 1 to 9.

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