Spin-orbit moment memory cell, preparation method thereof and magnetic random access memory

Abstract

The invention discloses a spin-orbit moment memory cell, a preparation method thereof and a magnetic random access memory. The spin-orbit moment storage unit comprises a magnetic tunnel junction, an orbit layer and a connecting part which are stacked in sequence, wherein the surface of one side, deviating from the magnetic tunnel junction, of the orbit layer is a first surface; the two connecting parts are arranged at an interval, each connecting part is provided with a first orthographic projection which partially falls into the first surface in the first direction, each first orthographic projection is provided with a first intersection point and a second intersection point which fall into the side line of the first surface, the first intersection point is the closest intersection point between the two connecting parts, and the second intersection point is the closest intersection point between the two connecting parts. The second intersection point is the farthest intersection point between the two connecting parts, and the first direction is the direction in which the track layer points to the magnetic tunnel junction. The spin-orbit moment storage unit can complete deterministic flipping under the condition of zero magnetic field.

Description

Technical Field

[0001] This application relates to the field of memory chips, and more specifically, to a spin orbital moment memory cell, its fabrication method, and a magnetic random access memory. Background Technology

[0002] Spin-orbit torque magnetic tunnel junction (SOT-MTJ) devices are one of the core structural types of MRAM products. Compared to spin-transfer torque magnetic tunnel junction (STT-MTJ) devices, SOT-MTJ devices feature faster write speeds, unlimited erase / write cycles, and read / write separation. A key structural feature of SOT-MTJ devices is the orbital layer, only a few nanometers thick, which provides an independent channel for write current, enabling read / write separation. However, the industrialization of SOT-MRAM currently faces several challenges:

[0003] 1. When performing MTJ etching, it is necessary to stop precisely at the SOT orbital layer, which results in an excessively small etching window. A small etching window is prone to over-etching, which affects device yield and uniformity, and may cause short circuits or open circuits in the device.

[0004] 2. SOT-MTJ devices require an auxiliary magnetic field to be applied along the current direction in order to achieve deterministic reversal of the vertical magnetic moment.

[0005] Currently, there is an urgent need to provide a SOT-MTJ device to overcome the aforementioned technical problems that exist during its industrialization. Summary of the Invention

[0006] This application provides a spin orbital moment storage cell, its fabrication method, and a magnetic random access memory to solve the problems of poor yield and uniformity of SOT-MTJ devices and the difficulty in achieving deterministic reversal of the vertical magnetic moment in related technologies.

[0007] According to one aspect of this application, a spin-orbit moment storage cell is provided, comprising a magnetic tunnel junction, an orbital layer, and connecting portions stacked sequentially, wherein: the side surface of the orbital layer facing away from the magnetic tunnel junction is a first surface; the connecting portions are two spaced apart, each connecting portion having a first orthographic projection partially falling into the first surface in a first direction, each first orthographic projection having a first intersection point and a second intersection point in the edge line falling into the first surface, the first intersection point being the closest intersection point between the two connecting portions, the second intersection point being the farthest intersection point between the two connecting portions, and the first direction being the direction from the orbital layer to the magnetic tunnel junction.

[0008] Optionally, the line connecting the two first intersection points is not equal to the line connecting the two second intersection points.

[0009] Optionally, the orthographic projection of the connecting part is selected from any one of a circle, a rectangle, a trapezoid, and an irregular polygon.

[0010] Optionally, the magnetic tunnel junction has vertical magnetization or in-plane magnetization.

[0011] Optionally, any cross section of the magnetic tunnel junction parallel to the first surface is designated as the first cross section. The shape of the first cross section is independently selected from any one of a circle, an ellipse, and a rectangle. The aspect ratio of the first cross section is 1 to 10, preferably 1 to 5.

[0012] Optionally, the side surface of the magnetic tunnel junction closest to the orbital layer is a second surface, and each of the connecting portions has a projection area falling into the second surface in a first direction, wherein the projection area accounts for less than or equal to 60% of the second surface.

[0013] Optionally, the magnetic tunnel junction has a first outer peripheral surface, and the orbital layer has a second outer peripheral surface that is coplanar with the first outer peripheral surface.

[0014] According to another aspect of this application, a magnetic random access memory is provided, including a storage array comprising a plurality of said spin-orbit moment storage cells, the spin-orbit moment storage cells comprising sequentially stacked magnetic tunnel junctions, orbital layers and connecting portions.

[0015] Optionally, any two adjacent spin-orbit moment storage cells share a connection portion, and multiple connection portions and multiple orbital layers are distributed at intervals along the same direction. Each connection portion has a projection area falling into the second surface of the magnetic tunnel junction in a first direction. The projection area of ​​each connection portion has the same shape, and the first direction is the direction in which the orbital layer points to the magnetic tunnel junction.

[0016] According to another aspect of this application, a method for fabricating a spin-orbit moment memory cell is also provided, comprising the following steps: providing a substrate and forming two spaced-apart connecting portions on the substrate; forming an orbital layer and a magnetic tunnel junction on the substrate, wherein the orbital layer is located between the magnetic tunnel junction and the substrate, the side surface of the orbital layer facing away from the magnetic tunnel junction is a first surface, each connecting portion has a first orthographic projection that partially falls into the first surface in a first direction, each first orthographic projection having a first intersection point and a second intersection point in the edge line falling into the first surface, the first intersection point being the closest intersection point between the two connecting portions, the second intersection point being the farthest intersection point between the two connecting portions, and the first direction being the direction from the orbital layer to the magnetic tunnel junction.

[0017] This application provides a spin-orbit moment memory cell, wherein the side surface of the orbital layer facing away from the magnetic tunnel junction is a first surface. Since each connection has a first orthographic projection that partially falls into the first surface in a first direction, the magnetic tunnel junction can be over-etched, increasing the etching window and reducing photolithographic alignment deviations in the etching step. This avoids the impact of low etching yield and uniformity on the device due to the small etching window caused by the need for precise stopping at the orbital layer during the etching of the magnetic tunnel junction. Furthermore, since each first orthographic projection has a first intersection point and a second intersection point in the edge line falling into the first surface, the first intersection point is the closest intersection point between the two connections, and the second intersection point is the farthest intersection point between the two connections. Thus, by constructing the shape and position of the above-mentioned connections, a current density gradient can be formed at the bottom of the magnetic tunnel junction, enabling deterministic flipping under zero magnetic field conditions. This avoids the need to apply an auxiliary magnetic field along the current direction to achieve deterministic flipping of the vertical magnetic moment in existing SOT-MTJ devices, reducing the integration difficulty of the device. 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 This is a cross-sectional structural schematic diagram of a spin orbital moment storage cell provided according to an embodiment of this application;

[0020] Figure 2 yes Figure 1 A schematic diagram of the spin orbit moment storage cell from below along the first direction is shown.

[0021] Figure 3 This is a cross-sectional structural schematic diagram of another spin orbital moment storage cell provided according to an embodiment of this application;

[0022] Figure 4 yes Figure 3 A schematic diagram of the structure of a spin orbital moment storage cell viewed from below along a first direction is shown.

[0023] Figure 5 yes Figure 3 A schematic diagram of another spin orbital moment storage cell shown from below along the first direction;

[0024] Figure 6 This is a partial cross-sectional structural diagram of a storage array in a magnetic random access memory according to an embodiment of this application;

[0025] Figure 7 yes Figure 6A schematic diagram of the storage array from below along the first direction is shown.

[0026] Figure 8 This is a schematic cross-sectional view of the substrate provided in a method for fabricating a spin orbital moment storage cell according to an embodiment of this application.

[0027] Figure 9 Is Figure 8 A schematic cross-sectional view of the structure after the connecting part is formed on the substrate is shown.

[0028] Figure 10 yes Figure 9 The diagram shown is a top view of the structure.

[0029] Figure 11 Is Figure 9 The diagram shows a cross-sectional structure of the structure after the formation of the track material layer, tunnel junction material layer and mask material layer on the substrate;

[0030] Figure 12 It is Figure 10 The diagram shows a cross-sectional structure of the magnetic tunnel junction material layer and the orbital material layer after etching to form the magnetic tunnel junction and the orbital layer.

[0031] Figure 13 yes Figure 12 The diagram shown is a top view of the structure.

[0032] Figure 14 It is to form a cover Figure 13 A schematic cross-sectional view of the structure behind the first protective layer on both sides of the magnetic tunnel junction is shown.

[0033] Figure 15 exist Figure 14 The diagram shows a cross-sectional structure of the structure after the top electrode is formed on the mask layer.

[0034] The above figures include the following reference numerals:

[0035] 10. Spin-orbit memory cell; 20. Bottom electrode; 21. Electrode section; 30. Connector section; 310. First connector section; 320. Second connector section; 40. Orbit layer; 41. Orbit material layer; 50. Magnetic tunnel junction; 51. Magnetic tunnel junction material layer; 501. First material; 510. Reference layer; 502. Second material; 520. Barrier layer; 503. Third material; 530. Free layer; 60. Mask layer; 61. Mask material layer; 70. Top electrode; 80. Insulating dielectric layer; 810. First insulating layer; 820. Second insulating layer; 90. First protective layer; 100. Top interconnect metal. Detailed Implementation

[0036] It should be noted that, unless otherwise specified, the embodiments and features described in this application can be combined with each other. This application will now be described in detail with reference to the accompanying drawings and embodiments.

[0037] To enable those skilled in the art to better understand the present application, the technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present application, and not all embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative effort should fall within the scope of protection of the present application.

[0038] It should be noted that the terms "first," "second," etc., in the specification, claims, and accompanying drawings of this application 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 this application 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.

[0039] As described in the background section, existing SOT-MRAM requires precise stopping at the SOT orbital layer during MTJ etching, resulting in an excessively small etching window. This leads to misalignment in photolithography during SOT-MTJ device miniaturization, resulting in poor yield and uniformity issues during mass production. To address these technical problems, this application provides a spin-orbit moment memory cell, its fabrication method, and a magnetic random access memory.

[0040] According to an embodiment of this application, a spin orbital moment storage cell is provided. Figures 1 to 5 This is a schematic diagram of the structure of the spin orbital moment storage unit provided in the embodiments of this application. For example... Figures 1 to 5As shown, the spin-orbit moment storage unit includes a magnetic tunnel junction 50, an orbital layer 40, and a connecting portion 30 stacked sequentially. The side surface of the orbital layer 40 facing away from the magnetic tunnel junction 50 is a first surface. There are two connecting portions 30 spaced apart. Each connecting portion 30 has a first orthographic projection that partially falls into the first surface in a first direction X. Each first orthographic projection has a first intersection point A and a second intersection point B in the edge line falling into the first surface. The first intersection point A is the closest intersection point between the two connecting portions 30, and the second intersection point B is the farthest intersection point between the two connecting portions 30. The first direction X is the direction from the orbital layer 40 to the magnetic tunnel junction 50.

[0041] In the above embodiments of this application, since each connection portion 30 has a first orthographic projection that partially falls into the first surface of the orbital layer in the first direction X, the magnetic tunnel junction 50 can be over-etched, which increases the etching window, reduces the photolithographic alignment deviation in the etching step, and avoids the impact of low etching yield on device yield and uniformity caused by the small etching window due to the need to precisely stop at the orbital layer 40 during the etching of the magnetic tunnel junction 50 in the prior art.

[0042] Furthermore, since each first orthographic projection has a first intersection point A and a second intersection point B falling into the edge line of the first surface, the first intersection point A is the closest intersection point between the two connecting parts 30, and the second intersection point B is the farthest intersection point between the two connecting parts 30, a current density gradient can be formed at the bottom of the magnetic tunnel junction 50 by constructing the shape and position of the connecting parts 30, so that it can complete the deterministic reversal under the condition of zero magnetic field. This avoids the need to apply an auxiliary magnetic field along the current direction to achieve the deterministic reversal of the vertical magnetic moment in the existing SOT-MTJ device, and reduces the integration difficulty of the device.

[0043] In the spin-orbit moment (SOT) memory cell described in this embodiment, the magnetic tunnel junction 50 is a multilayer structure. The magnetic tunnel junction 50 can take various forms depending on the application, including but not limited to in-plane MTJs, vertical MTJs, top-pinned MTJs, double-layer MgO MTJs, single-layer MgO MTJs, and polymorphic MTJs. For example, as... Figure 1 and Figure 3 As shown, the magnetic tunnel junction 50 in the embodiments of this application includes a free layer 530, a barrier layer 520, and a reference layer 510.

[0044] The magnetic tunnel junction 50 described above can be vertically magnetized or in-plane magnetized. In some optional embodiments, any cross-section of the magnetic tunnel junction 50 parallel to the first surface is designated as the first cross-section, the shape of which is independently selected from any one of a circle, an ellipse, and a rectangle, and the aspect ratio of the first cross-section is 1 to 10. Preferably, the aspect ratio of the first cross-section of the magnetic tunnel junction 50 is 1 to 5.

[0045] For example, the magnetic tunnel junction 50 described above adopts a vertically magnetized vertical MTJ, and the horizontal cross-sectional shape of the magnetic tunnel junction 50 is independently selected from one or more of the shapes of circles, ellipses and rectangles, preferably circles.

[0046] In another example, the magnetic tunnel junction 50 described above adopts an in-plane magnetized in-plane MTJ, and the horizontal cross-sectional shape of the magnetic tunnel junction 50 is independently selected from ellipse or rectangle, preferably ellipse.

[0047] Specifically, the materials of the free layer 530 and the reference layer 510 can be ferromagnetic materials, such as cobalt, iron, boron, nickel, ruthenium, iridium, platinum, etc., while the barrier layer 520 is a very thin insulating layer, and the insulating material of the barrier layer can include magnesium oxide, aluminum oxide, silicon oxide, etc. Those skilled in the art can reasonably select the types of materials for the free layer 530, the barrier layer 520, and the reference layer 510 according to actual needs, and the embodiments of this application do not make specific limitations.

[0048] In some alternative implementations, such as Figure 2 , Figure 4 and Figure 5 As shown, each connecting part 30 has a first orthographic projection that falls into the first surface of the track layer 40 in the first direction X. Each first orthographic projection has a first intersection point A and a second intersection point B in the edge line falling into the first surface. The first intersection point A is the intersection point with the closest distance between two connecting parts 30, and the second intersection point B is the intersection point with the farthest distance between two connecting parts. The line connecting the two first intersection points A and the line connecting the two second intersection points B are not equal.

[0049] Specifically, such as Figure 2 , Figure 4 and Figure 5 As shown, the connecting portion 30 includes a first connecting portion 310 and a second connecting portion 320 spaced apart. Both the first connecting portion 310 and the second connecting portion 320 have a first orthographic projection falling into the first surface of the track layer 40. The line connecting the first intersection point A of the first connecting portion 310 and the first intersection point A of the second connecting portion 320 is the first connecting line, and the line connecting the second intersection point B of the first connecting portion 310 and the second intersection point B of the second connecting portion 320 is the second connecting line. The first connecting line and the second connecting line are not equal.

[0050] Furthermore, in order to facilitate the construction of the current density gradient at the bottom of the magnetic tunnel junction (MTJ) and achieve zero magnetic field reversal of the vertical magnetic moment, the line connecting the two first intersection points A and the line connecting the two second intersection points B can also be parallel.

[0051] In some alternative embodiments, the orthographic projection of the connecting portion 30 is selected from any one of a circle, rectangle, trapezoid, and irregular polygon, and this application does not make a specific limitation.

[0052] Specifically, the shapes of the first orthographic projection of the first connecting portion 310 and the first orthographic projection of the second connecting portion 320 may be the same or different. The first orthographic projections of the first connecting portion 310 and the second connecting portion 320 can be centrally symmetric figures. The centrally symmetric figures can be independently selected from shapes such as circles, squares, and rectangles, or they can be selected from other polygons. Figure 2 and Figure 5 The image shows only the first orthographic projections of the first connecting portion 310 and the second connecting portion 320 as squares. However, the first orthographic projections of the first connecting portion 310 and the second connecting portion 320 can also be non-centrally symmetric figures, such as trapezoids or irregular polygons. Figure 4 The first orthographic projection of the first connecting portion 310 and the second connecting portion 320 is shown as a trapezoid, and the embodiments of this application are not specifically limited.

[0053] For example, the surface of the track layer 40 facing away from the magnetic tunnel junction 50 is a first surface. The first surface has a first centroid C. The first orthographic projections of the first connecting portion 310 and the second connecting portion 320 both have a second centroid D. The line connecting the second centroid D and the first centroid C of the first surface is not collinear. It can be understood that the line connecting the second centroid D and the first centroid C of the first orthographic projection of the first connecting portion 310 forms an angle α with the first centroid C of the first orthographic projection of the second connecting portion 320. Figure 2 As shown, the included angle α can be any of right angle, obtuse angle, and acute angle, and a current density gradient is constructed below the MTJ by adjusting the placement position.

[0054] In the SOT memory cell described in the embodiments of this application, the connection part 30 may be made of the same material or different materials, including but not limited to low resistivity metal materials such as W, Cu, Co, Fe, CoFeB and ferromagnetic metal materials.

[0055] In the above-described SOT storage unit of the embodiments of this application, such as Figure 1 and Figure 3As shown, the magnetic tunnel junction 50 and the track layer 40 have a bottom electrode 20 and a top electrode 70 on their respective sides. The bottom electrode 20 is located on the side of the track layer 40 away from the magnetic tunnel junction 50 and is connected to the connecting part 30 in a one-to-one correspondence, thereby realizing an electrical connection with the track layer 40 through the connecting part 30. The top electrode 70 is located on the side of the magnetic tunnel junction 50 located on the track layer 40. The bottom electrode 20 includes two spaced electrode parts 21, and the orthogonal projection of each electrode part 21 in the first direction X falls into the first surface of the track layer 40.

[0056] The material of the aforementioned track layer 40 can be a heavy metal material, such as W, Ta, Pt, WTax, PtCoO, PtMgO, AuPt, PtCr, PtHf, PtTi, BiSb, BiSe, etc. The electrode materials of the aforementioned bottom electrode 20 and the aforementioned top electrode 70 can be independently selected from any one or more alloy materials composed of silver, copper, aluminum, gold, titanium, platinum, palladium, tantalum, tantalum nitride, titanium nitride, cobalt, iron, nickel, and cobalt iron, but are not limited to the above types. The embodiments of this application do not make specific limitations.

[0057] In some alternative embodiments, the side surface of the magnetic tunnel junction 50 near the track layer 40 is a second surface, and each connection 30 has a projection area falling into the second surface in the first direction X, the projection area accounting for less than or equal to 60% of the second surface.

[0058] Specifically, if the connection area between the connecting part 30 and the magnetic tunnel junction 50 is too large, it will easily lead to a decrease in the efficiency of the spin flow generated by the orbital layer 40, which is not conducive to the flipping of the magnetic tunnel junction; if the connection area between the connecting part 30 and the magnetic tunnel junction 50 is too small, it will cause excessive manufacturing difficulty and make it difficult to control process deviations. Therefore, in this embodiment, by setting the overlap area ratio between the connecting part 30 and the magnetic tunnel junction 50 to meet the above range, it can not only reduce the manufacturing difficulty and make it easier to control process deviations, but also avoid the low efficiency of the spin flow of the orbital layer 40, which is conducive to the flipping of the magnetic tunnel junction.

[0059] In some alternative embodiments, the magnetic tunnel junction 50 has a first outer peripheral surface, and the orbital layer 40 has a second outer peripheral surface that is coplanar with the first outer peripheral surface.

[0060] Specifically, the aforementioned coplanar magnetic tunnel junction 50 and orbital layer 40 can be formed through the same etching step. This eliminates the need to stop at orbital layer 40 when etching the magnetic tunnel junction 50. As a result, the dimensions of orbital layer 40 and magnetic tunnel junction 50 can be defined simultaneously, avoiding alignment errors in the etching process. Furthermore, it allows for over-etching of the magnetic tunnel junction 50, increasing the etching window. This avoids the low device yield and poor uniformity caused by the need for precise stopping at orbital layer 40 during the etching of the magnetic tunnel junction 50, which results in an excessively small etching window in the prior art.

[0061] Furthermore, since the magnetic tunnel junction 50 in the spin-orbit-momentum memory cell is coplanar with the outer periphery of the orbital layer 40, the width and length of the orbital layers 40 on both sides of the magnetic tunnel junction 50 can be reduced, making the dimensions of the magnetic tunnel junction 50 and the orbital layer 40 similar. This avoids the impact of large size differences on device write efficiency and write current. Therefore, using the above-mentioned spin-orbit-momentum memory cell can not only improve etching yield but also improve device write efficiency and reduce write current.

[0062] like Figure 1 and Figure 3 As shown, the SOT memory cell described in this application embodiment may further include a first insulating layer 810, which surrounds the outer periphery of the connecting portion 30. The first insulating layer 810 may be silicon dioxide, and this application embodiment does not impose specific limitations.

[0063] In the above-described SOT storage unit of the embodiments of this application, such as Figure 1 As shown, a mask layer 60 may also be provided on the magnetic tunnel junction 50 so that the top electrode 70 is located on the side of the mask layer 60 away from the magnetic tunnel junction 50. Then, a top interconnect metal 100 may be further provided on the top electrode 70 so that the top electrode 70 can be led out through the top interconnect metal 100.

[0064] Specifically, in the fabrication process of the magnetic tunnel junction 50 and the orbital layer 40, a stacked orbital layer 40 material layer and a magnetic tunnel junction material layer can be formed first. Then, a mask layer 60 is set on the magnetic tunnel junction material layer. In the same etching process, the underlying orbital layer 40 material layer and the magnetic tunnel junction material layer are sequentially etched through the mask layer 60 to obtain the magnetic tunnel junction 50 and the orbital layer 40. Then, a top electrode 70 is set on the mask layer 60.

[0065] The materials of the mask layer 60 and the top interconnect metal 100 can be reasonably selected according to the prior art. For example, the mask layer 60 can be a tantalum nitride layer, and the top interconnect metal 100 can include tungsten and / or copper. This application embodiment does not make specific limitations.

[0066] In the above-described SOT storage unit of this application embodiment, such as Figure 1 As shown, the outer periphery of the mask layer 60, the first outer peripheral surface of the magnetic tunnel junction 50, and the second outer peripheral surface of the track layer 40 may also be covered with a first protective layer 90. In the fabrication process of the SOT memory cell, after the formation of the first protective layer 90, a second insulating layer 820 is formed to cover the first protective layer 90. The second insulating layer 820 and the first insulating layer 810 constitute an insulating dielectric layer 80.

[0067] Specifically, after etching to form the magnetic tunnel junction 50 and the orbital layer 40, a protective layer material, such as silicon nitride, is deposited to form a first protective layer 90 covering the first outer peripheral surface of the magnetic tunnel junction 50 and the second outer peripheral surface of the orbital layer 40. Figure 1 As shown, an insulating material is deposited on the substrate to encapsulate the first protective layer 90. Then, the insulating material and the first protective layer 90 are sequentially planarized until the top surface of the mask layer 60 is exposed. For example, chemical mechanical polishing (CMP) is used for this planarization process.

[0068] The second insulating layer 820 and the first insulating layer 810 may have the same insulating material or different insulating materials. For example, both the first insulating layer 810 and the second insulating layer 820 may include silicon dioxide. The first protective layer 90 may be formed of a material with high hardness, such as silicon nitride. This application does not specifically limit the application to this material.

[0069] According to embodiments of this application, a magnetic random access memory (RAM) is also provided, such as... Figure 6 and Figure 7 As shown, the magnetic random access memory includes a storage array, the aforementioned spin-orbit moment storage unit 10, and the spin-orbit moment storage unit 10 includes a magnetic tunnel junction 50, an orbital layer 40, and a connecting portion 30 stacked sequentially.

[0070] In the above embodiments of this application, the spin-orbit moment memory cell 10 with magnetic tunnel junction (MTJ) is made into an array, which can reduce the resistance of the region where MTJs are connected to each other, thereby improving the write efficiency. Moreover, by utilizing the voltage-regulated magnetic anisotropy (VCMA) effect, a voltage is applied above the MTJ, which can not only reduce its flip current, but also perform bit selection operation.

[0071] Furthermore, combined Figures 1 to 5The spin-orbit memory cell shown in the figure allows the magnetic tunnel junction 50 to be over-etched because each connection portion 30 has a first orthographic projection that partially falls into the first surface in the first direction X. This increases the etching window, reduces photolithographic alignment deviation in the etching step, and avoids the impact of low etching yield on device yield and uniformity caused by the small etching window due to the need for precise stopping at the orbital layer 40 during the etching of the magnetic tunnel junction 50 in the prior art.

[0072] Furthermore, since the side surface of the track layer 40 facing away from the magnetic tunnel junction 50 is the first surface, each connection 30 has a first orthographic projection that partially falls into the first surface of the track layer in the first direction X. Each first orthographic projection has a first intersection point A and a second intersection point B in the edge line falling into the first surface. The first intersection point A is the closest intersection point between two connection points 30, and the second intersection point B is the farthest intersection point between two connection points 30. Thus, by constructing the shape and position of the connection points 30, a current density gradient can be formed at the bottom of the magnetic tunnel junction 50, enabling it to complete deterministic reversal under zero magnetic field conditions. This avoids the need to apply an auxiliary magnetic field along the current direction to achieve deterministic reversal of the vertical magnetic moment in the existing SOT-MTJ device, reducing the implementation difficulty of the device.

[0073] In some alternative implementations, such as Figure 6 and Figure 7 As shown, any two adjacent spin-orbit moment storage cells 10 share a common connection portion 30, and multiple connection portions 30 and multiple orbital layers 40 are distributed at intervals along the same direction. Multiple connection portions 30 with the above-described positional relationship can be arranged in parallel. The surface of the magnetic tunnel junction 50 closest to the orbital layer 40 is a second surface. Each connection portion 30 has a projection area falling into the second surface in the first direction X, and the projection areas of each connection portion 30 have the same shape.

[0074] For example, in Figure 6 and Figure 7 In the storage array shown, each spin-orbit moment storage cell 10 can be as follows: Figure 3 and Figure 4 As shown, the array includes a magnetic tunnel junction 50, an orbital layer 40, and a connecting portion 30 stacked sequentially. The connecting portion 30 is shared by adjacent spin orbital moment storage units 10. In each spin orbital moment storage unit 10, the side surface of the orbital layer 40 facing away from the magnetic tunnel junction 50 is a first surface. The connecting portion 30 includes a first connecting portion 310 and a second connecting portion 320 spaced apart. Both the first connecting portion 310 and the second connecting portion 320 have a first orthographic projection that partially falls into the second surface in the first direction X. The first surface may have a first centroid C. Each first orthographic projection is independently selected from a trapezoid or an irregular polygon.

[0075] In another example, Figure 6 and Figure 7 In the storage array shown, each spin-orbit moment storage cell 10 can be as follows: Figures 1 to 3 as well as Figure 5 As shown, the device includes a magnetic tunnel junction 50, an orbital layer 40, and a connecting portion 30 stacked sequentially. The connecting portion 30 is shared by adjacent spin orbital moment storage units 10. In each spin orbital moment storage unit 10, the side surface of the orbital layer 40 facing away from the magnetic tunnel junction 50 is a first surface. The connecting portion 30 includes a first connecting portion 310 and a second connecting portion 320 spaced apart. Both the first connecting portion 310 and the second connecting portion 320 have a first orthographic projection that partially falls into the second surface in the first direction X. Each first orthographic projection is independently selected from a centrally symmetric figure such as a square.

[0076] According to an embodiment of this application, a method for fabricating a spin-orbit moment storage cell is also provided, comprising the following steps:

[0077] S1, providing a substrate, and forming two spaced-apart connecting parts on the substrate;

[0078] S2, an orbital layer and a magnetic tunnel junction are formed on the substrate. The orbital layer is located between the magnetic tunnel junction and the substrate. Each connection has a first orthographic projection that partially falls into the first surface in a first direction. Each first orthographic projection has a first intersection point and a second intersection point in the edge line falling into the first surface. The first intersection point is the intersection point with the closest distance between the two connections, and the second intersection point is the intersection point with the farthest distance between the two connections. The first direction is the direction from the orbital layer to the magnetic tunnel junction.

[0079] In the above embodiments of this application, since the side surface of the track layer facing away from the magnetic tunnel junction is the first surface, each first orthographic projection has a first intersection point and a second intersection point falling into the edge line of the first surface. The first intersection point is the intersection point with the closest distance between the two connecting parts, and the second intersection point is the intersection point with the farthest distance between the two connecting parts. Thus, by constructing the shape and position of the connecting parts, a current density gradient is formed at the bottom of the magnetic tunnel junction, enabling it to complete deterministic reversal under zero magnetic field conditions. This avoids the need to apply an auxiliary magnetic field along the current direction to achieve deterministic reversal of the vertical magnetic moment in the SOT-MTJ device in the prior art, and reduces the integration difficulty of the device.

[0080] Furthermore, since the aforementioned coplanar magnetic tunnel junction and orbital layer are formed through the same etching step, it is not necessary to stop at the orbital layer when etching the magnetic tunnel junction. This not only allows the dimensions of the orbital layer and the magnetic tunnel junction to be defined simultaneously, avoiding alignment deviations in the etching process, but also allows the magnetic tunnel junction to be over-etched, increasing the etching window and reducing photolithographic alignment deviations in the etching step. This avoids the impact of low etching yield and uniformity on device yield caused by the need to precisely stop at the orbital layer during the etching of the magnetic tunnel junction in the prior art, which results in an excessively small etching window.

[0081] The following will be combined with the appendix Figures 1 to 15 Exemplary embodiments of the method for fabricating a spin-orbit moment storage cell according to the present invention are described in more detail below. However, these exemplary embodiments may be implemented in many different forms and should not be construed as being limited to the embodiments set forth herein. It should be understood that these embodiments are provided so that the disclosure of this application is thorough and complete, and that the concept of these exemplary embodiments is fully conveyed to those skilled in the art.

[0082] First, proceed to step S1, as follows: Figures 8 to 10 As shown, a substrate is provided, and two spaced-apart connecting portions 30 are formed on the substrate, each connecting portion 30 having an exposed third surface.

[0083] In some alternative embodiments, the step of forming the substrate includes: forming two bottom electrodes 20 spaced apart in the first insulating layer 810, such as... Figure 8 As shown, after the step of forming the substrate, a conductive material is deposited and etched on the substrate to form connection portions 30 corresponding one-to-one with the bottom electrode 20, such as... Figure 9 and Figure 10 As shown.

[0084] For example, such as Figure 9 and Figure 10 As shown, the connecting portion 30 includes a first connecting portion 310 and a second connecting portion 320 spaced apart. Both the first connecting portion 310 and the second connecting portion 320 have a first orthographic projection that partially falls into the first surface in a first direction. Each first orthographic projection is a centrally symmetrical figure, and the third surface of each connecting portion 30 has a third centroid E. After the step of forming the magnetic tunnel junction and the track layer, the first orthographic projections of the first connecting portion 310 and the second connecting portion 320 on the first surface of the track layer both have a second centroid D, which can overlap with the aforementioned third centroid E.

[0085] The deposition processes for the aforementioned connecting portion 30, the first insulating layer 810, and the bottom electrode 20 can be reasonably selected according to actual needs, such as chemical vapor deposition. The substrate material can include any one or more of silicon, silicon carbide, gallium nitride, and aluminum nitride. The connecting portion 30 can be made of the same material or different materials, including but not limited to low resistivity metal materials such as W, Cu, Co, Fe, and CoFeB, and ferromagnetic metal materials. The first insulating layer 810 can be silicon dioxide. The electrode material forming the bottom electrode 20 can be independently selected from any one or more alloy materials composed of silver, copper, aluminum, gold, titanium, platinum, palladium, tantalum, tantalum nitride, titanium nitride, cobalt, iron, nickel, and cobalt iron. This application embodiment does not specifically limit the specific materials.

[0086] In some alternative embodiments, the orthographic projection of the connecting portion 30 is selected from any one of a circle, rectangle, trapezoid, and irregular polygon, and this application does not make a specific limitation.

[0087] After providing the substrate with the bottom electrode, step S2 is performed, as follows: Figures 11 to 15 As shown, an orbital layer 40 and a magnetic tunnel junction 50 are formed on a substrate. The orbital layer 40 is located between the magnetic tunnel junction 50 and the substrate. The side of the orbital layer 40 facing away from the magnetic tunnel junction 50 is a first surface. Each connecting part 30 has a first orthographic projection that partially falls into the first surface in a first direction X. Each first orthographic projection has a first intersection point A and a second intersection point B in the edge line falling into the first surface. The first intersection point A is the intersection point with the closest distance between the two connecting parts 30, and the second intersection point B is the intersection point with the farthest distance between the two connecting parts 30. The first direction X is the direction from the orbital layer 40 to the magnetic tunnel junction 50.

[0088] Specifically, the orbital layer 40 and the magnetic tunnel junction 50 can be formed in the same etching process, thereby allowing the dimensions of the orbital layer and the magnetic tunnel junction to be defined simultaneously, avoiding alignment deviation problems in the etching process of the orbital layer. At the same time, in order to increase the etching yield, the magnetic tunnel junction can also be over-etched to increase the etching window.

[0089] In some alternative embodiments, the steps of forming the orbital layer 40 and the magnetic tunnel junction 50 include: sequentially depositing orbital layer material, magnetic tunnel junction material, and masking material on a substrate having the connection portion 30 to form a sequentially stacked orbital material layer 41, magnetic tunnel junction material layer 51, and masking material layer 61, such as... Figure 11 As shown; the mask material layer 61 is patterned to obtain the mask layer 60, and the orbital material layer 41 and the magnetic tunnel junction material layer 51 are etched through the mask layer 60 to form the orbital layer 40 and the magnetic tunnel junction 50, as shown. Figure 12 and Figure 13 As shown.

[0090] The magnetic tunnel junction 50 described above can be vertically magnetized or in-plane magnetized. In some optional embodiments, any cross-section of the magnetic tunnel junction 50 parallel to the first surface is designated as the first cross-section, the shape of which is independently selected from any one of a circle, an ellipse, and a rectangle, and the aspect ratio of the first cross-section is 1 to 10. Preferably, the aspect ratio of the first cross-section of the magnetic tunnel junction 50 is 1 to 5.

[0091] After the magnetic tunnel junction 50 is formed, the connecting portion 30 may include a first connecting portion 310 and a second connecting portion 320 that are spaced apart. Both the first connecting portion 310 and the second connecting portion 320 have a first orthographic projection falling into the first surface of the track layer 40.

[0092] Specifically, the shapes of the first orthographic projection of the first connecting portion 310 and the first orthographic projection of the second connecting portion 320 may be the same or different. The first orthographic projections of the first connecting portion 310 and the second connecting portion 320 can be centrally symmetric figures. The centrally symmetric figures can be independently selected from shapes such as circles, squares, and rectangles, or they can be selected from other polygons. Figure 2 and Figure 5 The image shows only the first orthographic projections of the first connecting portion 310 and the second connecting portion 320 as squares. However, the first orthographic projections of the first connecting portion 310 and the second connecting portion 320 can also be non-centrally symmetric figures, such as trapezoids or irregular polygons. Figure 4 The first orthographic projection of the first connecting portion 310 and the second connecting portion 320 is shown as a trapezoid, and the embodiments of this application are not specifically limited.

[0093] For example, after forming the orbital layer 40 and the magnetic tunnel junction 50, as Figure 2 and Figure 13 As shown, the surface of the magnetic tunnel junction 50 closest to the track layer 40 is the second surface, and the surface of the track layer 40 away from the magnetic tunnel junction 50 is the first surface. The first surface has a first center of gravity A. The connecting portion 30 includes a first connecting portion 310 and a second connecting portion 320 spaced apart. Both the first connecting portion 310 and the second connecting portion 320 have an exposed third surface. Both the first connecting portion 310 and the second connecting portion 320 have a first orthographic projection falling into the first surface of the track layer 40. The line connecting the first intersection point A of the first connecting portion 310 and the first intersection point A of the second connecting portion 320 is the first connecting line, and the line connecting the second intersection point B of the first connecting portion 310 and the second intersection point B of the second connecting portion 320 is the second connecting line. The first connecting line and the second connecting line are not equal, and each first orthographic projection is a centrally symmetrical figure.

[0094] In the above example, after the orbital layer 40 and the magnetic tunnel junction 50 are formed, the first orthographic projections of both the first connecting portion 310 and the second connecting portion 320 have a second centroid D. Before the steps of forming the magnetic tunnel junction and the orbital layer, the second centroid D overlaps with the third centroid E. The line connecting the second centroid D and the first centroid C of the first surface is not collinear. This can be understood as the line connecting the second centroid D and the first centroid C of the first orthographic projection of the first connecting portion 310 and the first centroid C of the first orthographic projection of the second connecting portion 320 having an angle α, such as... Figure 2 As shown, the included angle α can be any of right angle, obtuse angle, and acute angle, and a current density gradient is constructed below the MTJ by adjusting the placement position.

[0095] In some optional embodiments, the above-mentioned orbital layer material can be a heavy metal material, such as platinum, palladium, hafnium, gold, tantalum, tungsten, iridium or a combination of these alloys, the above-mentioned mask material can be silicon nitride, and the above-mentioned first protective layer 90 can be formed of a material with high hardness, such as silicon nitride. The embodiments of this application do not make specific limitations.

[0096] For example, the steps of forming the above-mentioned magnetic tunnel junction include: sequentially depositing a first material 501, a second material 502, and a third material 503, such as... Figure 11 As shown, the first material 501 and the third material 503 are ferromagnetic materials used to form the reference layer 510 and the free layer 530, such as cobalt, iron, boron, nickel, ruthenium, iridium, platinum, cobalt iron, cobalt iron boron, etc. The second material 502 is an insulating material used to form the barrier layer 520, such as magnesium oxide, aluminum oxide, silicon oxide, etc. After patterning the mask material layer 61 to obtain the mask layer 60, the magnetic tunnel junction material layer 51 and the orbital material layer 41 are etched through the mask layer 60 to form a magnetic tunnel junction 50 located on the orbital layer 40. The magnetic tunnel junction 50 includes a free layer 530, a barrier layer 520 and a reference layer 510 stacked together, such as... Figure 12 As shown.

[0097] It should be noted that the magnetic tunnel junctions prepared in the embodiments of this application are not limited to the above-described structures. The magnetic tunnel junctions can take many forms depending on the application, including but not limited to in-plane MTJs, vertical MTJs, top-pinned MTJs, bottom-pinned MTJs, double-layer MgO MTJs, single-layer MgO MTJs, and polymorphic MTJs.

[0098] In some alternative embodiments, after the steps of forming the orbital layer 40 and the magnetic tunnel junction 50, such as Figure 14As shown, the preparation method provided in this application embodiment further includes: depositing a first protective layer 90 on a substrate so that the first protective layer 90 covers the outer periphery of the mask layer 60, the first outer peripheral surface of the magnetic tunnel junction 50 and the second outer peripheral surface of the orbital layer 40; forming a second insulating layer 820 covering the first protective layer 90, wherein the second insulating layer 820 and the first insulating layer 810 constitute an insulating dielectric layer 80.

[0099] The second insulating layer 820 and the first insulating layer 810 may have the same insulating material or different insulating materials. For example, both the first insulating layer 810 and the second insulating layer 820 may include silicon dioxide. The first protective layer 90 may be formed of a material with high hardness, such as silicon nitride. This application does not specifically limit the application to this material.

[0100] After forming the second insulating layer 820 as described above, the preparation method provided in this application embodiment may further include: forming a top electrode 70 on the mask layer 60, such as... Figure 15 As shown; then a top interconnect metal 100 can be further provided on the top electrode 70 to lead out the top electrode 70 through the top interconnect metal 100, as shown. Figure 1 As shown.

[0101] The electrode material of the top electrode 70 can be independently selected from any one or more alloy materials composed of silver, copper, aluminum, gold, titanium, platinum, palladium, tantalum, tantalum nitride and titanium nitride. The top interconnect metal 100 can be a tungsten layer, but is not limited to the above types. The embodiments of this application do not make specific limitations.

[0102] It should also be noted that the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article, or apparatus. Unless otherwise specified, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes that element.

[0103] The above are merely embodiments of this application and are not intended to limit the scope of 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 scope of the claims of this application.

Claims

1. A spin-orbit moment storage cell, characterized in that, It includes a magnetic tunnel junction, a track layer, and a connecting section stacked sequentially, wherein: The surface of the track layer facing away from the magnetic tunnel junction is the first surface; The connecting parts are two spaced apart. Each connecting part has a first orthographic projection that partially falls into the first surface in a first direction. Each first orthographic projection has a first intersection point and a second intersection point in the edge line falling into the first surface. The first intersection point is the closest intersection point between the two connecting parts, and the second intersection point is the farthest intersection point between the two connecting parts. The first direction is the direction from the track layer to the magnetic tunnel junction.

2. The spin-orbit moment storage unit according to claim 1, characterized in that, The line connecting the two first intersection points is not equal to the line connecting the two second intersection points.

3. The spin-orbit moment storage unit according to claim 1, characterized in that, The orthographic projection of the connecting part is selected from any one of the following: circle, rectangle, trapezoid, and irregular polygon.

4. The spin-orbit moment storage unit according to claim 1, characterized in that, The magnetic tunnel junction has either vertical magnetization or in-plane magnetization.

5. The spin-orbit moment storage unit according to claim 1, characterized in that, The first cross section is any section parallel to the first surface of the magnetic tunnel junction. The shape of the first cross section is independently selected from any one of a circle, an ellipse, and a rectangle. The aspect ratio of the first cross section is 1 to 10, preferably 1 to 5.

6. The spin-orbit moment storage unit according to any one of claims 1 to 5, characterized in that, The side surface of the magnetic tunnel junction closest to the orbital layer is a second surface, and each of the connecting portions has a projection area falling into the second surface in a first direction, wherein the projection area accounts for less than or equal to 60% of the second surface.

7. The spin-orbit moment storage unit according to any one of claims 1 to 5, characterized in that, The magnetic tunnel junction has a first outer peripheral surface, and the orbital layer has a second outer peripheral surface that is coplanar with the first outer peripheral surface.

8. A magnetic random access memory, comprising a storage array, characterized in that, The storage array includes a plurality of spin-orbit moment storage units as described in any one of claims 1 to 7, wherein the spin-orbit moment storage unit includes a magnetic tunnel junction, an orbital layer, and a connecting portion stacked sequentially.

9. The magnetic random access memory according to claim 8, characterized in that, Any two adjacent spin-orbit moment storage cells share a connection portion. Multiple connection portions and multiple orbital layers are distributed at intervals along the same direction. Each connection portion has a projection area falling into the second surface of the magnetic tunnel junction in a first direction. The projection area of ​​each connection portion has the same shape. The first direction is the direction in which the orbital layer points to the magnetic tunnel junction.

10. A method for fabricating a spin-orbit moment storage cell, characterized in that, Includes the following steps: A substrate is provided, and two connecting portions spaced apart are formed on the substrate; An orbital layer and a magnetic tunnel junction are formed on the substrate. The orbital layer is located between the magnetic tunnel junction and the substrate. The side of the orbital layer facing away from the magnetic tunnel junction is a first surface. Each connection has a first orthographic projection that partially falls into the first surface in a first direction. Each first orthographic projection has a first intersection point and a second intersection point that fall into the edge line of the first surface. The first intersection point is the closest intersection point between two connection points, and the second intersection point is the farthest intersection point between two connection points. The first direction is the direction from the orbital layer to the magnetic tunnel junction.

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