Magnetic storage structure and preparation method for magnetic storage structure
Patent Information
- Authority / Receiving Office
- WO · WO
- Patent Type
- Applications
- Current Assignee / Owner
- Filing Date
- 2026-02-10
- Publication Date
- 2026-08-13
Smart Images
Figure CN2026078318_13082026_PF_FP_ABST
Abstract
Description
Magnetic storage structure and its fabrication method
[0001] This disclosure claims priority to Chinese Patent Application No. 202510146087.1, filed on February 10, 2025, entitled "Magnetic Storage Structure and Method for Preparing Magnetic Storage Structure", the entire contents of which are incorporated herein by reference. Technical Field
[0002] This disclosure relates to the field of semiconductor memory design and manufacturing, and more specifically, to a magnetic memory structure and a method for fabricating the magnetic memory structure. Background Technology
[0003] Spin-orbit torque-based magnetic tunnel junction (SOT-MTJ) magnetic random access memory (SOT-MRAM) is a next-generation non-volatile magnetic random access memory. It utilizes spin-orbit torque as the information writing method, enabling SOT devices to achieve nanosecond-level write speeds. Its read and write separation mode makes it possible for SOT-MRAM to achieve unlimited writes.
[0004] The currently disclosed SOT-MRAM memory cell architectures are all based on MTJ etching stopping on the spin orbital moment material. This architecture design has very high requirements for the process of the layers before and after the SOT orbital: on the one hand, it is necessary to precisely control the film layer at which the etching stops. The thickness of the SOT orbital layer is very small, only a few nanometers, and it is easy to be etched through during the over-etching process, resulting in the orbital layer being open and the device being scrapped; on the other hand, TJ etching can only stop on the SOT orbital, without any space for over-etching, which makes it difficult to clean the metal backsplatter of the device, and easily leads to short circuit failure of the device.
[0005] Self-aligned SOT etching architecture is an effective way to solve the above problems. Its advantage lies in the one-step etching of the SOT track and TJ stack, avoiding the damage to the SOT track caused by TJ stack etching and the impact of metal backspatter on the TJ stack during the two-step formation process. It can improve yield and save photomasks, effectively reducing costs; however, this integrated solution has the problem of low track current density and insufficient flipping capability at both ends of the SOT. Summary of the Invention
[0006] The main objective of this disclosure is to provide a magnetic storage structure and a method for fabricating the magnetic storage structure, so as to solve the problem that the low track current density and insufficient flipping capability at both ends of the SOT are caused by the self-aligned SOT etching process in the prior art.
[0007] To achieve the above objectives, according to one aspect of this disclosure, a magnetic storage structure is provided, comprising: a magnetic tunnel junction; a spin-orbit torque layer stacked on top of the magnetic tunnel junction; a first conductive portion located on the side of the spin-orbit torque layer away from the magnetic tunnel junction, wherein the surface end of the first conductive portion near the spin-orbit torque layer has a first notch, and the portion of the end of the first conductive portion other than the first notch has a first protrusion, the first protrusion of the first conductive portion being in contact with the spin-orbit torque layer; and a second conductive portion located on the side of the spin-orbit torque layer away from the magnetic tunnel junction and spaced apart from the first conductive portion, wherein the surface end of the second conductive portion near the spin-orbit torque layer has a second notch, and the portion of the end of the second conductive portion other than the second notch has a second protrusion, the second protrusion of the second conductive portion being in contact with the spin-orbit torque layer.
[0008] Optionally, there are multiple magnetic tunnel junctions and spin-orbit torque layers in a one-to-one correspondence, and the first conductive part and the second conductive part are each one.
[0009] Optionally, there are multiple magnetic tunnel junctions and spin-orbit torque layers in a one-to-one correspondence, multiple first conductive parts and multiple second conductive parts in a one-to-one correspondence, and multiple first conductive parts and multiple magnetic tunnel junctions in a one-to-one correspondence.
[0010] Optionally, the first notch is adjacent to the first protrusion, and the second notch is adjacent to the second protrusion.
[0011] Optionally, the magnetic storage structure further includes a substrate, a first conductive portion and a second conductive portion are disposed on the substrate at intervals, and a magnetic tunnel junction is located on the side of the first conductive portion and the second conductive portion away from the substrate; in the stacking direction of the magnetic tunnel junction and the spin-orbit torque layer, the first protrusion has a first height on the substrate, the first notch has a second height on the substrate, and the height difference between the first height and the second height is 5 to 30 nm.
[0012] Optionally, the first protrusion has a first width in the first direction, the first notch has a second width in the first direction, the first width is smaller than the second width, and the first direction is perpendicular to the stacking direction of the magnetic tunnel junction and the spin-orbit torque layer.
[0013] Optionally, the first conductive portion and the second conductive portion are symmetrically arranged based on the stacking direction of the magnetic tunnel junction and the spin-orbit torque layer.
[0014] According to another aspect of this disclosure, a method for fabricating a magnetic storage structure is provided. The method includes: providing a substrate; forming a first conductive portion and a second conductive portion on one side of the substrate, the first conductive portion and the second conductive portion being spaced apart; forming a spin-orbit torque layer and a magnetic tunnel junction on the side of the first conductive portion and the second conductive portion away from the substrate, the spin-orbit torque layer and the magnetic tunnel junction being stacked; forming a first notch at the end of the surface of the first conductive portion near the spin-orbit torque layer, the portion of the end of the first conductive portion other than the first notch forming a first protrusion; forming a second notch at the end of the second conductive portion near the spin-orbit torque layer, the portion of the end of the second conductive portion other than the second notch forming a second protrusion; the first protrusion of the first conductive portion is in contact with the spin-orbit torque layer, and the second protrusion of the second conductive portion is in contact with the spin-orbit torque layer.
[0015] Optionally, the steps of forming the spin-orbit torque layer and the magnetic tunnel junction include: forming a stacked spin-orbit torque material layer and a storage material layer on the side of the first conductive portion and the second conductive portion away from the substrate; and patterning the storage material layer and the spin-orbit torque material layer using a self-aligned etching technique to form the magnetic tunnel junction and the spin-orbit torque layer.
[0016] Optionally, the steps of forming the first notch and the second notch include: during the patterning of the storage material layer and the spin-orbit torque material layer using a self-aligned etching technique, over-etching the storage material layer and the spin-orbit torque material layer so that the end point of the over-etching is located below the surface of the spin-orbit torque layer on the side away from the storage material layer.
[0017] This disclosure provides a magnetic storage structure. The magnetic storage structure includes a magnetic tunnel junction, a spin-orbit torque layer, a first conductive portion, and a second conductive portion. The spin-orbit torque layer and the magnetic tunnel junction are stacked. The first conductive portion is located on the side of the spin-orbit torque layer away from the magnetic tunnel junction, and its surface end near the spin-orbit torque layer has a first notch. The portion of the first conductive portion, excluding the first notch, has a first protrusion, which contacts the spin-orbit torque layer. The second conductive portion is located on the side of the spin-orbit torque layer away from the magnetic tunnel junction and is spaced apart from the first conductive portion. Its surface end near the spin-orbit torque layer has a second notch, and its portion of the second conductive portion, excluding the second notch, has a second protrusion, which contacts the spin-orbit torque layer. Based on these technical features, the magnetic storage structure of this application increases the current density in the portion of the spin-orbit torque layer that contacts the first and second conductive portions, thereby improving the switching efficiency of the storage device having the magnetic storage structure of this application. Attached Figure Description
[0018] The accompanying drawings, which form part of this disclosure, are used to provide a further understanding of this disclosure. The illustrative embodiments of this disclosure and their descriptions are used to explain this disclosure and do not constitute an undue limitation of this disclosure. In the drawings:
[0019] Figure 1 shows a cross-sectional schematic diagram of a magnetic storage structure in the current technology;
[0020] Figure 2 shows a cross-sectional schematic diagram of a magnetic storage structure according to an embodiment of the present disclosure;
[0021] Figure 3 shows a schematic cross-sectional view of the substrate after the formation of the first conductive portion and the second conductive portion in a method for fabricating a magnetic storage structure according to an embodiment of the present disclosure.
[0022] Figure 4 shows a schematic cross-sectional view of the substrate after the spin orbit torque material layer, storage material layer, hard mask material layer and photomask structure are formed on the substrate shown in Figure 3.
[0023] Figure 5 shows a schematic cross-sectional view of the substrate after a hard mask layer has been formed on the substrate shown in Figure 4.
[0024] Figure 6 shows a schematic cross-sectional view of the substrate after the formation of a magnetic tunnel junction, a spin orbital torque layer, and a protective material layer on the substrate shown in Figure 5.
[0025] Figure 7 shows a schematic cross-sectional view of part A of the substrate shown in Figure 5.
[0026] The above figures include the following reference numerals:
[0027] 101. Bottom electrode structure; 102. SOT orbital layer; 103. MTJ;
[0028] 10. First conductive part; 20. Second conductive part; 30. Spin-orbit torque layer; 301. Spin-orbit torque material layer; 40. Magnetic tunnel junction; 401. Storage material layer; 50. Hard mask layer; 501. Hard mask material layer; 60. Top electrode; 70. Top metal interconnect; 80. Bottom metal interconnect; 90. Protective layer; 901. Protective material layer; 100. Insulating dielectric layer; 110. Substrate; 120. Photomask structure; 130. First notch; 140. First protrusion; 150. Second notch; 160. Second protrusion. Detailed Implementation
[0029] It should be noted that, unless otherwise specified, the embodiments and features described in this disclosure can be combined with each other. This disclosure will now be described in detail with reference to the accompanying drawings and embodiments.
[0030] To enable those skilled in the art to better understand the present disclosure, the technical solutions of the present disclosure will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of the present disclosure, and not all embodiments. Based on the embodiments of the present disclosure, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of the present disclosure.
[0031] It should be noted that the terms "first," "second," etc., in the specification, claims, and accompanying drawings of this disclosure 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 disclosure 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.
[0032] As described in the background section, spin-orbit torque (MTJ) based magnetic random access memory (MRRAM) typically involves etching the MTJ layer until it stops on the MTJ layer. However, because the MTJ layer is very thin, only a few nanometers, it is easily etched through during over-etching, leading to an open circuit in the MTJ layer and rendering the MRRAM unusable. Therefore, it is necessary to precisely control the MTJ etching to stop only on the MTJ layer, leaving no over-etching space. This makes it difficult to clean up metal sputtering, easily leading to short-circuit failure. Based on this, existing technologies employ a self-aligned SOT etching process, allowing the MTJ and MTJ layer to be etched in a single step. However, in the prior art, after the MTJ103 and SOT orbital layer 102 are etched using the aforementioned self-aligned SOT etching process, the MTJ103 and SOT orbital layer 102 often completely cover the bottom electrode structure 101, as shown in Figure 1. Therefore, for the magnetic random access memory in the integrated scheme, the coverage area of the MTJ103 on the SOT orbital layer 102 increases. Since the current needs to flow through the area of the SOT orbital layer 102 covered by the entire MTJ103, the larger coverage area may lead to uneven current distribution on the SOT orbital layer 102, especially at both ends. This may result in insufficient current density at the ends of the SOT orbital layer 102 to provide adequate switching capability. Therefore, to solve the problem of low orbital current density and insufficient switching capability below both ends of the SOT orbital layer 102 caused by the prior art self-aligned SOT etching process, this application provides a magnetic storage structure and a method for fabricating the magnetic storage structure.
[0033] According to one aspect of this application, a magnetic storage structure is provided, as shown in FIG2. The magnetic storage structure includes: a magnetic tunnel junction 40; a spin-orbit torque layer 30, which is stacked on top of the magnetic tunnel junction 40; a first conductive portion 10 located on the side of the spin-orbit torque layer 30 away from the magnetic tunnel junction 40, and the end of the first conductive portion 10 near the spin-orbit torque layer 30 has a first notch 130, and the end portion of the first conductive portion 10 other than the first notch 130 has a first protrusion 140, the first protrusion 140 of the first conductive portion 10 being in contact with the spin-orbit torque layer 30; a second conductive portion 20 located on the side of the spin-orbit torque layer 30 away from the magnetic tunnel junction 40 and spaced apart from the first conductive portion 10, the end portion of the second conductive portion 20 near the spin-orbit torque layer 30 has a second notch 150, and the end portion of the second conductive portion 20 other than the second notch 150 has a second protrusion 160, the second protrusion 160 of the second conductive portion 20 being in contact with the spin-orbit torque layer 30.
[0034] Specifically, the magnetic storage structure further includes a substrate 110, with a first conductive portion 10 and a second conductive portion 20 disposed at intervals on the substrate 110, i.e., as shown in FIG2, the first conductive portion 10 and the second conductive portion 20 are located on one side of the substrate 110. Furthermore, a magnetic tunnel junction 40 is located on the side of the first conductive portion 10 and the second conductive portion 20 away from the substrate 110.
[0035] Optionally, the first conductive portion 10 and the second conductive portion 20 are symmetrically arranged about the longitudinal axis of the magnetic tunnel junction 40 and the spin-orbit torque layer 30. The longitudinal axis extends parallel to the stacking direction of the magnetic tunnel junction 40 and the spin-orbit torque layer 30. In other words, the first conductive portion 10 and the second conductive portion 20 are symmetrically arranged based on the stacking direction of the magnetic tunnel junction 40 and the spin-orbit torque layer 30.
[0036] Specifically, the magnetic storage structure may include one or more magnetic tunnel junctions 40. Furthermore, for magnetic storage devices based on spin-orbit torque, the magnetic storage structure may also include one or more spin-orbit torque layers 30. It should be noted that when the magnetic storage structure of this application includes one magnetic tunnel junction 40, the magnetic storage structure also includes one spin-orbit torque layer 30; when the magnetic storage structure of this application includes multiple magnetic tunnel junctions 40, the magnetic storage structure also includes multiple spin-orbit torque layers 30, and the multiple magnetic tunnel junctions 40 and the multiple spin-orbit torque layers 30 correspond one-to-one.
[0037] Optionally, as shown in Figure 2, the projection area of each magnetic tunnel junction 40 on the corresponding spin-orbit torque layer 30 overlaps with the surface area of the spin-orbit torque layer 30; in other words, in a preset horizontal plane perpendicular to the stacking direction of the magnetic tunnel junction 40 and the spin-orbit torque layer 30, the projection of each magnetic tunnel junction 40 in the preset horizontal plane has the same shape and the same size as the projection of the corresponding spin-orbit torque layer 30 in the preset horizontal plane.
[0038] Optionally, the projection area of each magnetic tunnel junction 40 onto the corresponding spin-orbit torque layer 30 is located within the surface of the spin-orbit torque layer 30, and the area of the projection area of each magnetic tunnel junction 40 onto the corresponding spin-orbit torque layer 30 is smaller than the surface area of the spin-orbit torque layer 30. It should be noted in this embodiment that in a cross-section along the stacking direction of the magnetic tunnel junction 40 and the spin-orbit torque layer 30, the extension direction of the side of the magnetic tunnel junction 40 overlaps with the extension direction of the side of the spin-orbit torque layer 30.
[0039] Specifically, when the magnetic storage structure of this application includes multiple magnetic tunnel junctions 40, the magnetic storage structure also includes one or more first conductive portions 10 and one or more second conductive portions 20. It should be noted that when the magnetic storage structure of this application includes one first conductive portion 10, the magnetic storage structure also includes one second conductive portion 20, as shown in FIG2; when the magnetic storage structure of this application includes multiple first conductive portions 10, the magnetic storage structure also includes multiple second conductive portions 20, and the multiple first conductive portions 10 and the multiple second conductive portions 20 correspond one-to-one.
[0040] Specifically, as shown in Figure 2, each first conductive portion 10 has a first notch 130 and a first protrusion 140, and the first notch 130 and the first protrusion 140 are interdependent. It should be noted that although the first notch 130 and the first protrusion 140 are described as additional structures of the first conductive portion 10, the first notch 130 and the first protrusion 140 are still an inseparable part of the first conductive portion 10, and together with the first conductive portion 10, they constitute a complete structure.
[0041] Similarly, each second conductive portion 20 has a second notch 150 and a second protrusion 160, and the second notch 150 and the second protrusion 160 are interdependent. It should be noted that although the second notch 150 and the second protrusion 160 are described as additional structures of the second conductive portion 20, the second notch 150 and the second protrusion 160 are still an integral part of the second conductive portion 20, and together with the second conductive portion 20, they constitute a complete structure.
[0042] Optionally, for the first conductive portion 10 and the second conductive portion 20 that are provided in a one-to-one correspondence with the spin-orbit torque layer 30, the contact area between the first protrusion 140 of each first conductive portion 10 and the spin-orbit torque layer 30 is less than half of the surface area of the first conductive portion 10, and the contact area between the second protrusion 160 of each second conductive portion 20 and the spin-orbit torque layer 30 is less than half of the surface area of the second conductive portion 20. The surface areas of the first conductive part 10 and the second conductive part 20 are both orthogonal projection areas in a preset horizontal plane located in the stacking direction of the magnetic tunnel junction 40 and the spin-orbit torque layer 30. For a first conductive part 10 and a second conductive part 20 shared by multiple spin-orbit torque layers 30, the total contact area between the first protrusion 140 of the first conductive part 10 and the multiple spin-orbit torque layers 30 is less than half of the surface area of the first conductive part 10, and the total contact area between the second protrusion 160 of the second conductive part 20 and the multiple spin-orbit torque layers 30 is less than half of the surface area of the second conductive part 20.
[0043] For example, the magnetic tunnel junction 40 may include a free layer, a barrier layer, and a fixed layer stacked together. The free layer is disposed in contact with the spin-orbit torque layer 30.
[0044] For example, the materials of the first conductive part 10 and the second conductive part 20 may include, but are not limited to, one or more of copper (Cu), aluminum (Al), tungsten (W), titanium (Ti), titanium nitride (TiN), tantalum (Ta), and tantalum nitride (TaN).
[0045] Applying the technical solution of this disclosure, a magnetic storage structure is provided. As shown in FIG2, the magnetic storage structure includes a magnetic tunnel junction 40, a spin-orbit torque layer 30, a first conductive portion 10, and a second conductive portion 20. The spin-orbit torque layer 30 and the magnetic tunnel junction 40 are stacked. The first conductive portion 10 is located on the side of the spin-orbit torque layer 30 away from the magnetic tunnel junction, and the end surface of the first conductive portion 10 near the spin-orbit torque layer 30 has a first notch 130. The portion of the end of the first conductive portion 10 other than the first notch 130 has a first protrusion 140, and the first protrusion 140 of the first conductive portion 10 is in contact with the spin-orbit torque layer 30. The second conductive portion 20 is located on the side of the spin-orbit torque layer 30 away from the magnetic tunnel junction 40 and is spaced apart from the first conductive portion 10. The end surface of the second conductive portion 20 near the spin-orbit torque layer 30 has a second notch 150, and the portion of the second conductive portion 20 other than the second notch 150 has a second protrusion 160. The second protrusion 160 of the second conductive portion 20 is in contact with the spin-orbit torque layer 30. Based on the above technical features, the magnetic storage structure of this application can increase the current density in the portion of the spin-orbit torque layer 30 that is in contact with the first conductive portion 10 and the second conductive portion 20, thereby improving the switching efficiency of the memory device having the magnetic storage structure of this application.
[0046] Furthermore, when the direction from the first conductive part 10 to the second conductive part 20 is considered the first direction and this first direction is perpendicular to the stacking direction of the magnetic tunnel junction 40 and the spin-orbit torque layer 30, for the spin-orbit torque layer 30 of this application, one end of the spin-orbit torque layer 30 in the first direction is only in contact with the first protrusion 140 of the first conductive part 10 (i.e., the spin-orbit torque layer 30 only contacts a portion of the surface of the first conductive part 10 or the spin-orbit torque layer 30 only covers a portion of the surface of the first conductive part 10), and the other end of the spin-orbit torque layer 30 in the first direction is only in contact with the second protrusion 160 of the second conductive part 20 (i.e., the spin-orbit torque layer 30 only contacts a portion of the surface of the second conductive part 20 or the spin-orbit torque layer 30 only covers a portion of the surface of the second conductive part 20). Therefore, the resistance of the two ends of the spin-orbit torque layer 30 in the first direction is low. Because the current in the spin-orbit torque layer 30 tends to flow along the path with lower resistance in the spin-orbit torque layer 30, compared to the prior art where the spin-orbit torque layer 30 contacts the entire surface of the electrode layer (the spin-orbit torque layer 30 completely covers the entire surface of the electrode layer), in this application, the spin-orbit torque layer 30 is only in contact with the first protrusion 140 of the first conductive portion 10 at one end in the first direction, which can increase the current density at that end of the spin-orbit torque layer 30. Similarly, in this application, the spin-orbit torque layer 30 is only in contact with the second protrusion 160 of the second conductive portion 20 at the other end in the first direction, which also increases the current density at that end of the spin-orbit torque layer 30. Therefore, in the magnetic storage structure of this application, the current density at both ends of the spin-orbit torque layer 30 along the first direction is increased, thereby improving the switching efficiency of the memory device having this magnetic storage structure.
[0047] Specifically, in a top view along the stacking direction of the magnetic tunnel junction 40 and the spin-orbit torque layer 30, the shapes of the magnetic tunnel junction 40 and the spin-orbit torque layer 30 may include, but are not limited to, circles, ellipses, or polygons.
[0048] For example, when the magnetic tunnel junction 40 and the spin-orbit torque layer 30 are elliptical in the above top view, the major axis of the ellipse can be the first direction, thereby further reducing the contact area between the spin-orbit torque layer 30 and the first protrusion 140, increasing the current density at both ends of the spin-orbit torque layer 30 along the first direction, and thus improving the switching efficiency of the memory device having the magnetic storage structure.
[0049] Additionally, as shown in Figure 2, the aforementioned magnetic storage structure may further include a hard mask layer 50, a top electrode 60, and a top metal interconnect 70. The hard mask is in contact with the surface of the magnetic tunnel junction 40 away from the spin-orbit torque layer 30; the top electrode 60 is in contact with the surface of the hard mask layer 50 away from the magnetic tunnel junction 40; and the top metal interconnect 70 is in contact with the surface of the top electrode 60 away from the hard mask layer 50.
[0050] Furthermore, as shown in FIG2, the aforementioned magnetic storage structure may also include a bottom metal interconnect 80 or a contact plug structure. The contact plug structure may include a bottom electrode (i.e., the first conductive portion 10 and the second conductive portion 20 in this application) and a bottom metal interconnect 80 stacked together. In the case where the magnetic storage device only includes a contact plug structure, the bottom electrode (i.e., the first conductive portion 10 and the second conductive portion 20 in this application) in the contact plug structure is in contact with the surface of the spin-orbit torque layer 30 away from the magnetic tunnel junction 40, and the bottom electrode (i.e., the first conductive portion 10 and the second conductive portion 20 in this application) of the contact plug is located between the spin-orbit torque layer 30 and the bottom metal interconnect 80.
[0051] Specifically, the bottom electrode may include the aforementioned first bottom electrode and second bottom electrode. The bottom metal connection 80 may include a first bottom metal connection and a second bottom metal connection. Furthermore, the first bottom metal connection may be in contact with the first bottom electrode (i.e., the first conductive part 10 in this application), and the second bottom metal connection may be in contact with the second bottom electrode (i.e., the second conductive part 20 in this application).
[0052] Further, as shown in Figure 2, the above-described magnetic storage structure may also include a protective layer 90 and an insulating dielectric layer 100. The protective layer 90 covers all sidewalls of the magnetic tunnel junction 40 and the spin-orbit torque layer 30, as well as the first notch 130 of each first conductive portion 10 and the second notch 150 of each second conductive portion 20. The insulating dielectric layer 100 is located at least between two adjacent first conductive portions 10 and second conductive portions 20, on the side of the first conductive portion 10 away from the second conductive portion 20, and on the side of the second conductive portion 20 away from the first conductive portion 10.
[0053] In some alternative embodiments, in order to improve the integration of the magnetic storage structure and / or simplify the process flow, there are multiple magnetic tunnel junctions 40 and spin-orbit torque layers 30 in a one-to-one correspondence, and the first conductive part 10 and the second conductive part 20 are each one.
[0054] Optionally, the first conductive portion 10 is the first bottom electrode of the magnetic storage structure, and the second conductive portion 20 is the second bottom electrode of the magnetic storage structure, so that the multiple magnetic tunnel junctions 40 in this embodiment share the first bottom electrode and the second bottom electrode. It is understood that, in this embodiment, as shown in FIG2, the magnetic storage structure further includes a bottom metal interconnect 80, which is located on the side of the first bottom electrode (i.e., the first conductive portion 10 in this application) and the second bottom electrode (i.e., the second conductive portion 20 in this application) away from the spin-orbit torque layer 30.
[0055] It is understood that the dimensions of the plurality of spin-orbit torque layers 30 located between the first conductive part 10 and the second conductive part 20 in the second direction may be the same or different. The second direction is perpendicular to the first direction and also perpendicular to the stacking direction of the magnetic tunnel junction 40 and the spin-orbit torque layers 30.
[0056] Optionally, the first conductive part 10 is the first bottom metal connection of the magnetic storage structure, and the second conductive part 20 is the second bottom metal connection of the magnetic storage structure. Thus, in this embodiment, the plurality of magnetic tunnel junctions 40 are directly in contact with the first bottom metal connection 80, and the plurality of magnetic tunnel junctions 40 are directly in contact with the second bottom metal connection.
[0057] In some alternative embodiments, in order to provide better isolation for adjacent magnetic tunnel junctions and / or to provide greater flexibility for the magnetic storage structure, there are multiple magnetic tunnel junctions 40 and spin-orbit torque layers 30 in a one-to-one correspondence, multiple first conductive portions 10 and multiple second conductive portions 20 in a one-to-one correspondence, and multiple first conductive portions 10 and multiple magnetic tunnel junctions in a one-to-one correspondence.
[0058] It is understandable that the dimensions of the multiple spin orbit torque layers 30 located between different first conductive portions 10 and second conductive portions 20 in the second direction may be the same or different.
[0059] In some alternative implementations, as shown in FIG2, the first notch 130 is adjacent to the first protrusion 140, and the second notch 150 is adjacent to the second protrusion 160.
[0060] In the above embodiment, the first notch 130 is located at the end of the surface of the first conductive part 10. By setting the first notch 130 adjacent to the first protrusion 140, the remaining part of the surface of the first conductive part 10 other than the first notch 130 can form the first protrusion 140. Thus, the first notch 130 and the first protrusion 140 can be prepared in the same process, simplifying the process flow.
[0061] Similarly, in this embodiment, as shown in FIG2, the second notch 150 is adjacent to the second protrusion 160.
[0062] In some alternative embodiments, in order to improve the reliability of the memory device having the above-described magnetic storage structure, in the stacking direction of the magnetic tunnel junction 40 and the spin-orbit torque layer 30, the first protrusion 140 has a first height on the substrate 110, and the first notch 130 has a second height on the substrate 110, with the height difference between the first height and the second height being 5 to 30 nm.
[0063] Similarly, in this embodiment, in the stacking direction of the magnetic tunnel junction 40 and the spin-orbit torque layer 30, the second protrusion 160 has a third height on the substrate 110, and the second notch 150 has a fourth height on the substrate 110, with the height difference between the third height and the fourth height being 5 to 30 nm.
[0064] In some alternative embodiments, in order to effectively reduce the resistance of the contact area between the spin orbital torque layer 30 and the first protrusion 140, the first protrusion 140 has a first width in a first direction, and the first notch 130 has a second width in a first direction, wherein the first width is smaller than the second width.
[0065] In some alternative implementations, in order for the spin-orbit torque-based magnetic storage device to generate sufficient spin-orbit torque at a low current to drive the magnetic moment reversal of the free layer of the magnetic tunnel junction 40, the material of the spin-orbit torque layer 30 includes, but is not limited to, heavy metal materials or topological materials.
[0066] For example, the material of the spin orbital torque layer 30 may include, but is not limited to, tungsten (W), tantalum (Ta), platinum (Pt) or bismuth selenide (BiSe).
[0067] According to another aspect of this disclosure, a method for fabricating a magnetic storage structure is provided, as shown in FIG3. The fabrication method includes: providing a substrate 110; forming a first conductive portion 10 and a second conductive portion 20 on one side of the substrate 110, the first conductive portion 10 and the second conductive portion 20 being disposed at intervals; forming a spin-orbit torque layer (not shown) and a magnetic tunnel junction (not shown) on the side of the first conductive portion 10 and the second conductive portion 20 away from the substrate 110, the spin-orbit torque layer and the magnetic tunnel junction being stacked; forming a first notch (not shown) on the surface end of the first conductive portion 10 near the spin-orbit torque layer, forming a first protrusion (not shown) on the portion of the end of the first conductive portion 10 other than the first notch; forming a second notch (not shown) on the surface end of the second conductive portion 20 near the spin-orbit torque layer, forming a second protrusion (not shown) on the portion of the end of the second conductive portion 20 other than the second notch; the first protrusion of the first conductive portion 10 being in contact with the spin-orbit torque layer, and the second protrusion of the second conductive portion 20 being in contact with the spin-orbit torque layer.
[0068] Optionally, as shown in FIG3, the substrate 110 has a bottom metal interconnect 80.
[0069] By applying the method for fabricating the magnetic storage structure of this application, after forming the first conductive portion 10 and the second conductive portion 20, this application simultaneously forms a magnetic tunnel junction and a spin-orbit torque layer on the side of the first conductive portion 10 and the second conductive portion 20 away from the substrate 110. This optimizes the etching process window of the magnetic tunnel junction and avoids the phenomenon that sputtered metal falls on the sidewall of the magnetic tunnel junction during the formation of the spin-orbit torque layer, causing short circuits in the device. This can improve the yield of on-chip devices. Furthermore, this application also forms a first notch at the end of the surface of the first conductive portion 10 near the spin-orbit torque layer, and forms a first protrusion at that end of the first conductive portion 10, such that at least one first protrusion of the first conductive portion 10 is in contact with the spin-orbit torque layer; and forms a second notch at the end of the surface of the second conductive portion 20 near the spin-orbit torque layer, and forms a second protrusion at that end of the second conductive portion 20, such that the second protrusion of the second conductive portion 20 is in contact with at least one spin-orbit torque layer, thereby increasing the current density in the spin-orbit torque layer at the contact portion with the first conductive portion 10 and the second conductive portion 20, thereby improving the switching efficiency of the memory device having the above-mentioned magnetic storage structure of this application.
[0070] Specifically, as shown in FIG3, in the step of forming the first conductive portion 10 and the second conductive portion 20, an insulating dielectric layer 100 may first be formed on one side surface of the substrate 110, and then the first conductive portion 10 and the second conductive portion 20 are formed in the insulating dielectric layer 100 at intervals. Thus, the insulating dielectric layer 100 may be located at least between the first conductive portion 10 and the second conductive portion 20, on the side of the first conductive portion 10 away from the second conductive portion 20, and on the side of the second conductive portion 20 away from the first conductive portion 10.
[0071] In some alternative embodiments, the steps of forming the spin-orbit torque layer and the magnetic tunnel junction include: forming a stacked spin-orbit torque material layer 301 and a storage material layer 401 on the side of the first conductive portion 10 and the second conductive portion 20 away from the substrate 110, as shown in FIG4; and patterning the storage material layer and the spin-orbit torque material layer using a self-aligned etching technique to form the magnetic tunnel junction and the spin-orbit torque layer.
[0072] Specifically, in the step employing self-aligned etching technology, a hard mask material layer 501 and a photomask structure 120 can be sequentially formed on the side of the storage material layer 401 away from the spin-orbit torque material layer 301, as shown in FIG. 4. Then, the hard mask material layer can be etched based on this photomask structure to obtain the hard mask layer 50, as shown in FIG. 5. Next, the photomask structure can be removed, and the storage material layer 401 and the spin-orbit torque material layer 301 can be sequentially etched based on the hard mask layer 50 to obtain the magnetic tunnel junction 40 and the spin-orbit torque layer 30, as shown in FIG. 6.
[0073] In some alternative embodiments, as shown in FIG6, the steps of forming the first notch 130 and the second notch 150 include: during the patterning of the storage material layer and the spin-orbit torque material layer using a self-aligned etching technique, over-etching the storage material layer and the spin-orbit torque material layer such that the end point of the over-etching is located below the surface of the spin-orbit torque layer 30 on the side away from the storage material layer.
[0074] Specifically, both the side of the first conductive portion 10 away from the second conductive portion 20 and the side of the second conductive portion 20 away from the first conductive portion 10 have an insulating dielectric layer 100. Thus, for the step of over-etching the storage material layer and the spin orbital material layer, the case where the end position of the over-etching stops below the surface of the spin orbital torque layer 30 away from the storage material layer corresponds to the following: the end position of the over-etching can stop in the insulating dielectric layer 100 on the side of the first conductive portion 10 away from the second conductive portion 20 and in the insulating dielectric layer 100 on the side of the second conductive portion 20 away from the first conductive portion 10. This allows a first notch 130 to be formed at the surface end of the first conductive portion 10 and a second notch 150 to be formed at the surface end of the second conductive portion 20. At this time, the portion of the end of the first conductive part 10, excluding the first notch 130, is in contact with the spin-orbit torque layer 30. This portion is the first protrusion 140 of the first conductive part 10. The portion of the end of the second conductive part 20, excluding the second notch 150, is in contact with the spin-orbit torque layer 30. This portion is the second protrusion 160 of the second conductive part 20, as shown in FIG6.
[0075] In addition, after forming the first notch 130 and the second notch 150, the method for fabricating the magnetic storage structure may further include: forming a protective material layer 901 on the side of the hard mask layer 50 away from the substrate 110, such that the protective material layer 901 at least covers the first notch 130 of each first conductive portion 10, the second notch 150 of each second conductive portion 20, all sidewalls of each spin-orbit torque layer 30, and all surfaces of each magnetic tunnel junction 40, as shown in Figures 6 and 7. The protective material layer is planarized, and a portion of the protective material layer located on the surface of the magnetic tunnel junction 40 away from the spin-orbit torque layer 30 is removed to form the protective layer 90, exposing the surface of the hard mask layer 50 away from the magnetic tunnel junction 40. This protective layer 90 at least covers the first notch 130 of each first conductive portion 10, the second notch 150 of each second conductive portion 20, all sidewalls of each spin-orbit torque layer 30, and all sidewalls of each magnetic tunnel junction 40, as shown in Figure 2.
[0076] Furthermore, the method for fabricating the magnetic storage structure may further include: forming a top electrode on the side of the hard mask layer 50 away from the magnetic tunnel junction 40; forming an insulating dielectric layer 100 on the side of the top electrode away from the magnetic tunnel junction 40; forming a via in the insulating dielectric layer 100 on the side of the magnetic tunnel junction 40 away from the spin-orbit torque layer 30 to penetrate the insulating dielectric layer 100 to the top electrode; and filling the via with a conductive material to form a top metal interconnect, as shown in Figure 2.
[0077] As can be seen from the above description, the embodiments of this disclosure achieve the following technical effects:
[0078] 1. A magnetic storage structure is provided using the technical solution of this disclosure. This magnetic storage structure includes a magnetic tunnel junction, a spin-orbit torque layer, a first conductive portion, and a second conductive portion. The spin-orbit torque layer and the magnetic tunnel junction are stacked. The first conductive portion is located on the side of the spin-orbit torque layer away from the magnetic band junction, and its surface end near the spin-orbit torque layer has a first notch. The portion of the first conductive portion, excluding the first notch, has a first protrusion, which contacts the spin-orbit torque layer. The second conductive portion is located on the side of the spin-orbit torque layer away from the magnetic tunnel junction and is spaced apart from the first conductive portion. The surface end of the second conductive portion near the spin-orbit torque layer has a second notch, and the portion of the second conductive portion, excluding the second notch, has a second protrusion, which contacts the spin-orbit torque layer. Based on the above technical features, the magnetic storage structure of this application increases the current density in the portion of the spin-orbit torque layer that contacts the first and second conductive portions, thereby improving the switching efficiency of the storage device having the magnetic storage structure of this application.
[0079] 2. Using the fabrication method of the magnetic storage structure of this application, after forming the first conductive portion and the second conductive portion, this application simultaneously forms a magnetic tunnel junction and a spin-orbit torque layer on the side of the first and second conductive portions away from the substrate. This optimizes the etching process window of the magnetic tunnel junction and avoids the phenomenon of short circuits caused by sputtered metal falling onto the sidewalls of the magnetic tunnel junction during the formation of the spin-orbit torque layer, thereby improving the on-chip device yield. Furthermore, this application also forms a first notch on the surface end of the first conductive portion near the spin-orbit torque layer and forms a first protrusion at that end of the first conductive portion, such that the first protrusion of the first conductive portion contacts at least one spin-orbit torque layer. Similarly, a second notch is formed on the surface end of the second conductive portion near the spin-orbit torque layer, and a second protrusion is formed at that end of the second conductive portion, such that the second protrusion of the second conductive portion contacts at least one spin-orbit torque layer. This increases the current density in the spin-orbit torque layer at the contact portion with the first and second conductive portions, thereby improving the switching efficiency of the memory device having the aforementioned magnetic storage structure of this application.
[0080] The above description is merely a preferred embodiment of this disclosure and is not intended to limit this disclosure. Various modifications and variations can be made to this disclosure by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this disclosure should be included within the scope of protection of this disclosure.
Claims
1. A magnetic storage structure, the magnetic storage structure comprising: Magnetic tunnel junction; A spin orbital torque layer is stacked with the magnetic tunnel junction; A first conductive portion is located on the side of the spin-orbit torque layer away from the magnetic tunnel junction, and the end of the surface of the first conductive portion near the spin-orbit torque layer has a first notch. The portion of the end of the first conductive portion other than the first notch has a first protrusion, and the first protrusion of the first conductive portion is in contact with the spin-orbit torque layer. The second conductive portion is located on the side of the spin-orbit torque layer away from the magnetic tunnel junction and is spaced apart from the first conductive portion. The end of the surface of the second conductive portion near the spin-orbit torque layer has a second notch, and the portion of the end of the second conductive portion other than the second notch has a second protrusion. The second protrusion of the second conductive portion is in contact with the spin-orbit torque layer.
2. The magnetic storage structure according to claim 1, wherein, The magnetic tunnel junction and the spin-orbit torque layer are multiple in a one-to-one correspondence, and the first conductive part and the second conductive part are each one.
3. The magnetic storage structure according to claim 2, wherein, The projected region of each magnetic tunnel junction on the corresponding spin-orbit torque layer overlaps with the surface region of the spin-orbit torque layer.
4. The magnetic storage structure according to claim 2, wherein, The projection region of each magnetic tunnel junction on the corresponding spin-orbit torque layer is located in the surface of the spin-orbit torque layer, and the area of the projection region of each magnetic tunnel junction on the corresponding spin-orbit torque layer is smaller than the surface area of the spin-orbit torque layer.
5. The magnetic storage structure according to claim 1, wherein, The magnetic tunnel junction includes a free layer, a barrier layer, and a fixed layer stacked together, wherein the free layer is in contact with the spin-orbit torque layer.
6. The magnetic storage structure according to claim 1, wherein, The materials of the first conductive part and the second conductive part include one or more of copper, aluminum, tungsten, titanium, titanium nitride, tantalum and tantalum nitride.
7. The magnetic storage structure according to claim 1, wherein, The magnetic tunnel junction and the spin-orbit torque layer are in one-to-one correspondence, the first conductive part and the second conductive part are in one-to-one correspondence, and the multiple first conductive parts and the multiple magnetic tunnel junctions are in one-to-one correspondence.
8. The magnetic storage structure according to any one of claims 1 to 7, wherein, The first notch is adjacent to the first protrusion, and the second notch is adjacent to the second protrusion.
9. The magnetic storage structure according to any one of claims 1 to 7, wherein, The magnetic storage structure further includes a substrate, with the first conductive portion and the second conductive portion disposed at intervals on the substrate, and the magnetic tunnel junction located on the side of the first conductive portion and the second conductive portion away from the substrate; In the stacking direction of the magnetic tunnel junction and the spin-orbit torque layer, the first protrusion has a first height on the substrate, the first notch has a second height on the substrate, and the height difference between the first height and the second height is 5 to 30 nm.
10. The magnetic storage structure according to claim 1, wherein, The first conductive portion and the second conductive portion are symmetrically arranged about the longitudinal axis of the magnetic tunnel junction and the spin-orbit torque layer, wherein the extending direction of the longitudinal axis is parallel to the stacking direction of the magnetic tunnel junction and the spin-orbit torque layer.
11. The magnetic storage structure according to any one of claims 1 to 7, wherein, The first protrusion has a first width in a first direction, the first notch has a second width in the first direction, the first width is smaller than the second width, and the first direction is perpendicular to the stacking direction of the magnetic tunnel junction and the spin orbital torque layer.
12. The magnetic storage structure according to any one of claims 1 to 7, wherein, In the stacking direction of the magnetic tunnel junction and the spin-orbit torque layer, the first conductive portion and the second conductive portion are symmetrically arranged based on the stacking direction.
13. The magnetic storage structure according to any one of claims 1 to 7, wherein, The magnetic storage structure further includes: a hard mask layer, a top electrode, and a top metal interconnect, wherein the hard mask is in contact with the surface of the magnetic tunnel junction away from the spin-orbit torque layer, the top electrode is in contact with the surface of the hard mask layer away from the magnetic tunnel junction, and the top metal interconnect is in contact with the surface of the top electrode away from the hard mask layer.
14. The magnetic storage structure according to any one of claims 1 to 7, wherein, The magnetic storage structure further includes a protective layer and an insulating dielectric layer, wherein the protective layer covers all sidewalls of the magnetic tunnel junction and the spin-orbit torque layer, as well as the first notch of each first conductive portion and the second notch of each second conductive portion, and the insulating dielectric layer is located at least between two adjacent first conductive portions and second conductive portions, on the side of the first conductive portion away from the second conductive portion, and on the side of the second conductive portion away from the first conductive portion.
15. A method for fabricating a magnetic storage structure as described in any one of claims 1 to 14, the method comprising: A substrate is provided, and a first conductive portion and a second conductive portion are formed on one side of the substrate, the first conductive portion and the second conductive portion being disposed at a distance from each other; A spin-orbit torque layer and a magnetic tunnel junction are formed on the side of the first conductive portion and the second conductive portion away from the substrate, and the spin-orbit torque layer and the magnetic tunnel junction are stacked. A first notch is formed at the end of the surface of the first conductive portion near the spin-orbit torque layer, and a first protrusion is formed at the end of the first conductive portion excluding the first notch. A second notch is formed at the end of the surface of the second conductive portion near the spin-orbit torque layer, and a second protrusion is formed at the end of the second conductive portion excluding the second notch. The first protrusion of the first conductive part is in contact with the spin-orbit torque layer, and the second protrusion of the second conductive part is in contact with the spin-orbit torque layer.
16. The preparation method according to claim 15, wherein, The steps of forming the spin-orbit torque layer and the magnetic tunnel junction include: A spin orbital torque material layer and a storage material layer are formed on the side of the first conductive portion and the second conductive portion away from the substrate; The storage material layer and the spin-orbit torque material layer are patterned using a self-aligned etching technique to form the magnetic tunnel junction and the spin-orbit torque layer.
17. The preparation method according to claim 16, wherein, The steps for forming the first gap and the second gap include: During the patterning process of the storage material layer and the spin-orbit torque material layer using self-aligned etching technology, the storage material layer and the spin-orbit torque material layer are over-etched so that the end position of the over-etching is located below the surface of the spin-orbit torque layer on the side away from the storage material layer.