Magnetic tunnel junctions and memory devices

Abstract

The application provides an MTJ and a memory device, the MTJ comprising a free layer, a barrier layer, a fixed layer and a composite pinning layer, the barrier layer being located on a surface of the free layer; the fixed layer being located on a surface of the barrier layer away from the free layer; the composite pinning layer being located on a surface of the fixed layer away from the barrier layer, and the composite pinning layer comprising a first pinning layer, a first coupling layer, a second pinning layer, a second coupling layer and a third pinning layer which are sequentially stacked on the surface of the fixed layer away from the barrier layer. The application sets the coupling layer between the pinning layers, and the interface coupling between the coupling layer and the pinning layer ensures that the vertical magnetic anisotropy of the composite pinning layer is strong, the adjacent pinning layers are fixed through the interlayer antiferromagnetic coupling of the intermediate coupling layer, which ensures that the magnetic moment of the composite pinning layer has strong stability in the external magnetic field, and solves the problem that the vertical magnetic anisotropy of the top pinning layer after the existing MTJ etching is weak, causing abnormal magnetization reversal characteristics.

Description

Technical Field

[0001] This application relates to the field of magnetic random access memory, and more specifically, to an MTJ and a storage device. Background Technology

[0002] Spin-orbit torque magnetic random access memory (SOT-MRAM) is a new generation of non-volatile memory. Compared to traditional memory, SOT-MRAM has lower power consumption, higher write speed, and better erasure and write resistance.

[0003] SOT-MRAM requires a top-pinned MTJ (Magnetic Tunnel Junction) thin-film structure. In this structure, the free layer is at the bottom, connected to the heavy metal layer, while the barrier layer, reference layer, and stationary layer are stacked upwards in sequence. On one hand, differences in crystal structure make the fabrication of the top pinned layer and the realization of a specific orientation structure extremely difficult. Conventional fabrication techniques often fail to achieve the ideal orientation structure of the top pinned layer, resulting in weak vertical magnetic anisotropy. On the other hand, the top pinned layer is susceptible to significant etching damage during micro / nano fabrication, leading to weak vertical magnetic anisotropy and abnormal magnetization reversal characteristics in the final MTJ device.

[0004] The information disclosed in the background section is only intended to enhance the understanding of the background art of the art described herein. Therefore, the background art may contain information that does not constitute prior art known to those skilled in the art in this country. Summary of the Invention

[0005] The main objective of this application is to provide an MTJ and a storage device to solve the problem in the prior art where the vertical magnetic anisotropy of the top pinning layer after MTJ etching is weak, resulting in abnormal magnetization reversal characteristics.

[0006] According to one aspect of the present invention, an MTJ is provided, comprising a free layer, a barrier layer, a fixing layer, and a composite pinning layer, wherein the barrier layer is located on the surface of the free layer; the fixing layer is located on the surface of the barrier layer away from the free layer; and the composite pinning layer is located on the surface of the fixing layer away from the barrier layer, wherein the composite pinning layer comprises a first pinning layer, a first coupling layer, a second pinning layer, a second coupling layer, and a third pinning layer sequentially stacked on the surface of the fixing layer away from the barrier layer.

[0007] Optionally, the composite pinning layer further includes a stacked structure located on the surface of the third pinning layer away from the second coupling layer, the stacked structure including alternately arranged third coupling layers and fourth pinning layers.

[0008] Optionally, the MTJ further includes a bottom electrode and a top electrode, wherein the bottom electrode is located on the surface of the free layer away from the barrier layer; and the top electrode is located on the surface of the composite pinning layer away from the fixing layer.

[0009] Optionally, the top electrode and the bottom electrode are both multilayer film structures, and the materials of the top electrode and the bottom electrode are independently selected from at least one of Ta, Ru, Pt, W and Mo.

[0010] Optionally, the material of the first pinning layer includes Co, and the thickness of the first pinning layer ranges from 0.6 nm to 2 nm.

[0011] Optionally, the second pinning layer includes at least one of [Co / Pt]n multilayer film, [Co / Pd]n multilayer film and [Co / Ni]n multilayer film, where 1≤n≤6 and n is a positive integer, and the thickness of the second pinning layer ranges from 2.0 to 5.0 nm.

[0012] Optionally, the third pinning layer includes a first material layer and a second material layer, wherein the first material layer comprises at least one of Co, CoFe, and CoFeB, the second material layer comprises at least one of Pt, Pd, and Ni, and the thickness of the third pinning layer ranges from 0.6 to 3.0 nm.

[0013] Optionally, the materials of the first coupling layer and the second coupling layer are independently selected from Ir or Ru.

[0014] Optionally, the barrier layer is made of MgO, and the free layer is made of at least one of Co, Fe, Ni, CoB, FeB, NiB, CoFe, NiFe, CoNi, and CoFeB.

[0015] According to another aspect of the present invention, a storage device is also provided, including any of the MTJs described above.

[0016] In an embodiment of the present invention, the MTJ includes a free layer, a barrier layer, a fixed layer, and a composite pinning layer. The barrier layer is located on the surface of the free layer; the fixed layer is located on the surface of the barrier layer away from the free layer; and the composite pinning layer is located on the surface of the fixed layer away from the barrier layer. The composite pinning layer includes a first pinning layer, a first coupling layer, a second pinning layer, a second coupling layer, and a third pinning layer sequentially stacked on the surface of the fixed layer away from the barrier layer. Compared to the weak vertical magnetic anisotropy of the top pinning layer in existing MTJs, the MTJ of this application, by setting a first pinning layer, a second pinning layer, and a third pinning layer on the fixing layer, and by setting a coupling layer between each pinning layer, ensures strong vertical magnetic anisotropy of the composite pinning layer through interface coupling between the coupling layer and the pinning layer. Neighboring pinning layers are fixed to each other through interlayer antiferromagnetic coupling via the intermediate coupling layer. This ensures strong stability of the magnetic moment of the composite pinning layer in an external magnetic field, solving the problem of weak vertical magnetic anisotropy of the top pinning layer after etching in existing MTJs, which causes abnormal magnetization reversal characteristics. Attached Figure Description

[0017] 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:

[0018] Figure 1 A schematic diagram of an MTJ structure according to a specific embodiment of this application is shown;

[0019] Figure 2 A schematic diagram of an MTJ structure according to another specific embodiment of this application is shown.

[0020] The above figures include the following reference numerals:

[0021] 10. Bottom electrode; 20. Free layer; 30. Barrier layer; 40. Fixed layer; 50. Top electrode; 101. First pinning layer; 102. First coupling layer; 103. Second pinning layer; 104. Second coupling layer; 105. Third pinning layer; 106. Third coupling layer; 107. Fourth pinning layer. Detailed Implementation

[0022] 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.

[0023] 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.

[0024] 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.

[0025] It should be understood that when an element (such as a layer, film, region, or substrate) is described as being "on" another element, the element may be directly on the other element, or there may be an intermediate element present. Furthermore, in the specification and claims, when an element is described as being "connected" to another element, the element may be "directly connected" to the other element, or "connected" to the other element via a third element.

[0026] As mentioned in the background section, existing MTJs suffer from weak vertical magnetic anisotropy in the top pinned layer after etching, resulting in abnormal magnetization reversal characteristics. To address these issues, a typical embodiment of this application provides an MTJ and a storage device.

[0027] According to an embodiment of this application, an MTJ is provided, and the MTJ provided in the embodiment of this application will be described below.

[0028] Figure 1 This is a schematic diagram of the MTJ structure according to an embodiment of this application. Figure 1As shown, the MTJ includes a free layer 20, a barrier layer 30, a fixing layer 40, and a composite pinning layer. The barrier layer 30 is located on the surface of the free layer 20; the fixing layer 40 is located on the surface of the barrier layer 30 away from the free layer 20; and the composite pinning layer is located on the surface of the fixing layer 40 away from the barrier layer 30. The composite pinning layer includes a first pinning layer 101, a first coupling layer 102, a second pinning layer 103, a second coupling layer 104, and a third pinning layer 105, which are sequentially stacked on the surface of the fixing layer 40 away from the barrier layer 30.

[0029] The aforementioned MTJ comprises a free layer, a barrier layer, a fixed layer, and a composite pinning layer stacked sequentially. The composite pinning layer includes a first pinning layer, a first coupling layer, a second pinning layer, a second coupling layer, and a third pinning layer stacked sequentially on the surface of the fixed layer away from the barrier layer. Compared to the problem of weak vertical magnetic anisotropy of the top pinning layer in existing MTJs, the MTJ of this application, by setting the first, second, and third pinning layers on the fixed layer and setting coupling layers between each pinning layer, ensures strong vertical magnetic anisotropy of the composite pinning layer through interfacial coupling between the coupling layers and the pinning layers. Adjacent pinning layers are fixed together through interlayer antiferromagnetic coupling via the intermediate coupling layer. This ensures strong stability of the magnetic moment of the composite pinning layer in an external magnetic field, solving the problem of weak vertical magnetic anisotropy of the top pinning layer after etching in existing MTJs, which causes abnormal magnetization reversal characteristics.

[0030] To further ensure good perpendicular magnetic anisotropy of the MTJ, according to a specific embodiment of this application, such as... Figure 2 As shown, the composite pinning layer further includes a stacked structure located on the surface of the third pinning layer 105 away from the second coupling layer 104. This stacked structure includes alternately arranged third coupling layers 106 and fourth pinning layers 107. By continuing to provide a stacked structure on the third pinning layer 105, the vertical magnetic anisotropy of the top pinning layer can be further ensured, further guaranteeing the strong stability of the magnetic moment of the top pinning layer in an external magnetic field, thus solving the problem of abnormal magnetization reversal characteristics of the MTJ after etching.

[0031] According to another specific embodiment of this application, the MTJ further includes a bottom electrode 10 and a top electrode 50, such as... Figure 1 As shown, the bottom electrode 10 is located on the surface of the free layer 20 away from the barrier layer 30; the top electrode 50 is located on the surface of the composite pinning layer away from the fixing layer 40.

[0032] According to another specific embodiment of this application, the top electrode and the bottom electrode are both multilayer film structures, and the materials of the top electrode and the bottom electrode are independently selected from at least one of Ta, Ru, Pt, W and Mo.

[0033] According to a specific embodiment of this application, the material of the first pinning layer includes Co, and the thickness of the first pinning layer ranges from 0.6 nm to 2 nm.

[0034] According to another specific embodiment of this application, the second pinning layer includes at least one of [Co / Pt]n multilayer film, [Co / Pd]n multilayer film and [Co / Ni]n multilayer film, where 1≤n≤6 and n is a positive integer, and the thickness of the second pinning layer is in the range of 2.0 to 5.0 nm.

[0035] According to another specific embodiment of this application, the third pinning layer includes a first material layer and a second material layer. The material of the first material layer includes at least one of Co, CoFe, and CoFeB. The material of the second material layer includes at least one of Pt, Pd, and Ni. The thickness of the third pinning layer ranges from 0.6 to 3.0 nm.

[0036] According to a specific embodiment of this application, the materials of the first coupling layer and the second coupling layer are independently selected from Ir or Ru.

[0037] According to another specific embodiment of this application, the material of the barrier layer includes MgO, and the material of the free layer includes at least one selected from Co, Fe, Ni, CoB, FeB, NiB, CoFe, NiFe, CoNi, and CoFeB. The material of the fixed layer includes at least one selected from Co, Fe, Ni, CoB, FeB, NiB, CoFe, NiFe, CoNi, CoFeNi, CoFeB, NiFeB, CoNiB, CoFeNiB, FePt, FePd, CoPt, CoPd, CoFePt, CoFePd, FePtPd, CoPtPd, and CoFePtPd.

[0038] In practical applications, the materials of the barrier layer, the free layer, and the fixed layer are not limited to those described above. Those skilled in the art can flexibly select the materials for the structural layers according to the actual situation. In one specific embodiment, the material of the barrier layer may further include AlO₂. X MgAlO X TiO X TaO X GaO X With FeO X At least one of them.

[0039] According to another typical embodiment of this application, a storage device is also provided, the storage device including any of the above-described MTJs.

[0040] The aforementioned storage device includes the aforementioned MTJ. Compared with the problem of weak vertical magnetic anisotropy of the top pinning layer in the prior art, the MTJ of this application provides the aforementioned first pinning layer, the aforementioned second pinning layer, and the aforementioned third pinning layer on the aforementioned fixing layer, and provides a coupling layer between each pinning layer. The interface coupling between the aforementioned coupling layer and the aforementioned pinning layer ensures that the vertical magnetic anisotropy of the composite pinning layer is strong. The adjacent pinning layers are fixed to each other through interlayer antiferromagnetic coupling through the intermediate coupling layer. This ensures that the magnetic moment of the composite pinning layer has strong stability in the external magnetic field, solves the problem of weak vertical magnetic anisotropy of the top pinning layer after etching of the existing MTJ, which causes abnormal magnetization reversal characteristics, and thus ensures better performance of the storage device.

[0041] To enable those skilled in the art to better understand the technical solution of this application, the following description will be provided in conjunction with specific embodiments.

[0042] Example 1

[0043] Formation as Figure 1 The MTJ structure shown is formed through the following specific processes:

[0044] The free layer 20 is grown on the bottom electrode 10. The bottom electrode 10 is a multilayer film structure. The material of the bottom electrode 10 is independently selected from at least one of Ta, Ru, Pt, W and Mo. The material of the free layer 20 includes at least one of Co, Fe, Ni, CoB, FeB, NiB, CoFe, NiFe, CoNi and CoFeB.

[0045] The barrier layer 30 is grown on the free layer 20, and the material of the barrier layer 30 includes MgO.

[0046] The aforementioned fixing layer 40 and the aforementioned first pinning layer 101 are grown on the aforementioned barrier layer 30. The material of the fixing layer includes at least one of Co, Fe, Ni, CoB, FeB, NiB, CoFe, NiFe, CoNi, CoFeNi, CoFeB, NiFeB, CoNiB, CoFeNiB, FePt, FePd, CoPt, CoPd, CoFePt, CoFePd, FePtPd, CoPtPd, and CoFePtPd. The material of the aforementioned first pinning layer includes Co, and the thickness of the aforementioned first pinning layer ranges from 0.6 nm to 2 nm.

[0047] The first coupling layer 102 and the second pinning layer 103 are grown on the first pinning layer 101. The second pinning layer includes at least one of [Co / Pt]n multilayer film, [Co / Pd]n multilayer film and [Co / Ni]n multilayer film, where 1≤n≤6 and n is a positive integer, and the thickness of the second pinning layer is in the range of 2.0 to 5.0 nm. The material of the first coupling layer is independently selected from Ir or Ru.

[0048] The second coupling layer 104 and the third pinning layer 105 are grown on the second pinning layer 103. The third pinning layer includes a first material layer and a second material layer. The material of the first material layer includes at least one of Co, CoFe and CoFeB. The material of the second material layer includes at least one of Pt, Pd and Ni. The thickness of the third pinning layer ranges from 0.6 to 3.0 nm. The material of the second coupling layer is independently selected from Ir or Ru.

[0049] A top electrode 50 is fabricated on the third pinning layer 105. The top electrode 50 is a multilayer film structure, and the material of the top electrode 50 is independently selected from at least one of Ta, Ru, Pt, W and Mo.

[0050] Example 2

[0051] Formation as Figure 2 The MTJ structure shown is formed through the following specific processes:

[0052] The free layer 20 is grown on the bottom electrode 10. The bottom electrode 10 is a multilayer film structure. The material of the bottom electrode 10 is independently selected from at least one of Ta, Ru, Pt, W and Mo. The material of the free layer 20 includes at least one of Co, Fe, Ni, CoB, FeB, NiB, CoFe, NiFe, CoNi and CoFeB.

[0053] The barrier layer 30 is grown on the free layer 20, and the material of the barrier layer 30 includes MgO.

[0054] The aforementioned fixing layer 40 and the aforementioned first pinning layer 101 are grown on the aforementioned barrier layer 30. The material of the fixing layer includes at least one of Co, Fe, Ni, CoB, FeB, NiB, CoFe, NiFe, CoNi, CoFeNi, CoFeB, NiFeB, CoNiB, CoFeNiB, FePt, FePd, CoPt, CoPd, CoFePt, CoFePd, FePtPd, CoPtPd, and CoFePtPd. The material of the aforementioned first pinning layer includes Co, and the thickness of the aforementioned first pinning layer ranges from 0.6 nm to 2 nm.

[0055] The first coupling layer 102 and the second pinning layer 103 are grown on the first pinning layer 101. The second pinning layer includes at least one of [Co / Pt]n multilayer film, [Co / Pd]n multilayer film and [Co / Ni]n multilayer film, where 1≤n≤6 and n is a positive integer, and the thickness of the second pinning layer is in the range of 2.0 to 5.0 nm. The material of the first coupling layer is independently selected from Ir or Ru.

[0056] The second coupling layer 104 and the third pinning layer 105 are grown on the second pinning layer 103. The third pinning layer includes a first material layer and a second material layer. The material of the first material layer includes at least one of Co, CoFe and CoFeB. The material of the second material layer includes at least one of Pt, Pd and Ni. The thickness of the third pinning layer ranges from 0.6 to 3.0 nm. The material of the second coupling layer is independently selected from Ir or Ru.

[0057] The third coupling layer 106 and the fourth pinning layer 107 are grown on the third pinning layer 105. The fourth pinning layer 107 includes a first material layer and a second material layer. The material of the first material layer includes at least one of Co, CoFe and CoFeB. The material of the second material layer includes at least one of Pt, Pd and Ni. The thickness of the fourth pinning layer 107 ranges from 0.6 to 3.0 nm. The material of the third coupling layer 106 is independently selected from Ir or Ru.

[0058] A top electrode 50 is fabricated on the fourth pinning layer 107. The top electrode 50 is a multilayer film structure, and the material of the top electrode 50 is independently selected from at least one of Ta, Ru, Pt, W and Mo.

[0059] In the above embodiments of the present invention, the descriptions of each embodiment have different focuses. For parts not described in detail in a certain embodiment, please refer to the relevant descriptions of other embodiments.

[0060] As can be seen from the above description, the embodiments of this application achieve the following technical effects:

[0061] 1) The MTJ described in this application comprises a free layer, a barrier layer, a fixed layer, and a composite pinning layer stacked sequentially. The composite pinning layer comprises a first pinning layer, a first coupling layer, a second pinning layer, a second coupling layer, and a third pinning layer stacked sequentially on the surface of the fixed layer away from the barrier layer. Compared with the problem of weak vertical magnetic anisotropy of the top pinning layer in the prior art, the MTJ of this application provides the first pinning layer, the second pinning layer, and the third pinning layer on the fixed layer, and provides coupling layers between each pinning layer. The interface coupling between the coupling layer and the pinning layer ensures strong vertical magnetic anisotropy of the composite pinning layer. Adjacent pinning layers are fixed to each other through interlayer antiferromagnetic coupling via the intermediate coupling layer. This ensures strong stability of the magnetic moment of the composite pinning layer in the external magnetic field, solving the problem of weak vertical magnetic anisotropy of the top pinning layer after etching in existing MTJs, which causes abnormal magnetization reversal characteristics.

[0062] 2) The storage device described in this application includes the aforementioned MTJ. Compared to the problem of weak vertical magnetic anisotropy of the top pinning layer in the prior art, the MTJ of this application provides the first pinning layer, the second pinning layer, and the third pinning layer on the fixed layer, and provides a coupling layer between each pinning layer. The interface coupling between the coupling layer and the pinning layer ensures strong vertical magnetic anisotropy of the composite pinning layer. Neighboring pinning layers are fixed to each other through interlayer antiferromagnetic coupling via the intermediate coupling layer. This ensures that the magnetic moment of the composite pinning layer has strong stability in the external magnetic field, solving the problem of weak vertical magnetic anisotropy of the top pinning layer after etching of the existing MTJ, which causes abnormal magnetization reversal characteristics, thereby ensuring better performance of the storage device.

[0063] The above description is merely a preferred embodiment of this application and is not intended to limit this application. Various modifications and variations can be made to this application by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. An MTJ, characterized in that, include: Free layer; A barrier layer is located on the surface of the free layer; A fixed layer is located on the surface of the barrier layer that is away from the free layer; A composite pinning layer is located on the surface of the fixing layer away from the barrier layer. The composite pinning layer includes a first pinning layer, a first coupling layer, a second pinning layer, a second coupling layer, and a third pinning layer that are sequentially stacked on the surface of the fixing layer away from the barrier layer. Adjacent pinned layers are fixed to each other through interlayer antiferromagnetic coupling via an intermediate coupling layer; The composite pinning layer also includes: A stacked structure is located on the surface of the third pinning layer away from the second coupling layer, the stacked structure comprising alternating third coupling layers and fourth pinning layers; The material of the first pinning layer includes Co, and the thickness of the first pinning layer ranges from 0.6 nm to 2 nm; The second pinning layer includes at least one of [Co / Pt]n multilayer film, [Co / Pd]n multilayer film and [Co / Ni]n multilayer film, where 1≤n≤6 and n is a positive integer, and the thickness of the second pinning layer is in the range of 2.0~5.0nm; The third pinning layer includes a first material layer and a second material layer. The first material layer includes at least one of Co, CoFe, and CoFeB. The second material layer includes at least one of Pt, Pd, and Ni. The thickness of the third pinning layer ranges from 0.6 to 3.0 nm.

2. The MTJ according to claim 1, characterized in that, The MTJ also includes: The bottom electrode is located on the surface of the free layer away from the barrier layer; The top electrode is located on the surface of the composite pinning layer away from the fixing layer.

3. The MTJ according to claim 2, characterized in that, The top electrode and the bottom electrode are both multilayer film structures, and the materials of the top electrode and the bottom electrode are independently selected from at least one of Ta, Ru, Pt, W and Mo.

4. The MTJ according to any one of claims 1 to 3, characterized in that, The materials of the first coupling layer and the second coupling layer are independently selected from Ir or Ru.

5. The MTJ according to any one of claims 1 to 3, characterized in that, The barrier layer is made of MgO, and the free layer is made of at least one of Co, Fe, Ni, CoB, FeB, NiB, CoFe, NiFe, CoNi, and CoFeB.

6. A storage device, characterized in that, include: The MTJ according to any one of claims 1 to 5.

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