SOT-MRAM memory cell and SOT-MRAM memory

Abstract

The invention provides an SOT-MRAM (Single Oxide Transistor Magnetic Random Access Memory) storage unit and an SOT-MRAM memory. Comprising a substrate, an enhancement layer, an SOT effect layer and a magnetic tunnel junction which are sequentially stacked from bottom to top, the SOT effect layer has a strong spin-orbit coupling effect, and spin current perpendicular to the interface direction is formed after current is introduced; the enhancement layer is used for assisting the SOT effect layer in turning the magnetization direction of a free layer of the magnetic tunnel junction, and the enhancement layer is of a composite layer structure and comprises a conductive layer; the substrate comprises a conductive layer, an insulator layer located below the conductive layer, and / or a tunneling isolation layer located above the conductive layer, the insulator layer is used for forming an interface built-in electric field with the adjacent substrate and conductive layer and changing the spin polarization direction of electrons migrating downwards, and the tunneling isolation layer is used for separating electrons with opposite spin polarization directions. The magnetization overturning efficiency of the free layer can be improved.

Description

Technical Field

[0001] The present invention relates to the technical field of magnetic memory, and in particular to a SOT-MRAM storage unit and a SOT-MRAM memory. Background Art

[0002] Spin-orbit torque magnetic random access memory (SOT-MRAM) has higher charge-spin conversion efficiency than spin-transfer torque magnetic random access memory (STT-MRAM), and has the characteristics of high speed, low power consumption, and high reliability, and has strong application potential. The SOT-MRAM storage cell includes a SOT effect layer that provides spin-orbit torque (SOT) and a magnetic tunnel junction (MTJ).

[0003] In the prior art, SOT-MRAM uses a single-layer SOT effect layer, such as Figure 1 As shown, current is passed into the SOT effect layer, and due to the spin-orbit coupling (SOC) effect, the current is converted into spin current. After the SOT effect layer generates spin current, electrons with opposite spin polarization directions migrate toward the free layer and substrate in the adjacent MTJ, respectively, and accumulate at the SOT effect layer / free layer interface and the SOT effect layer / substrate interface. The electrons accumulated at the SOT effect layer / free layer interface transfer spin momentum to the free layer in the MTJ, causing the magnetization of the free layer to flip and write information. The spin-polarized electrons accumulated at the SOT effect layer / substrate interface, due to the rebound effect of the SOT effect layer / substrate interface, partially rebound back to the SOT effect layer / free layer interface, causing the spins of the spin-polarized electrons with opposite spin polarization directions to cancel each other, reducing the spin current intensity at the SOT effect layer / free layer interface, and thus reducing the magnetization flip efficiency of the free layer. Summary of the invention

[0004] In order to solve the above problems, the present invention provides a SOT-MRAM storage unit and a SOT-MRAM memory, which can improve the magnetization switching efficiency of the free layer.

[0005] In a first aspect, the present invention provides a SOT-MRAM storage cell, comprising:

[0006] substrate;

[0007] a reinforcing layer, located on the substrate;

[0008] A SOT effect layer, located on the enhancement layer, wherein the SOT effect layer has a strong spin-orbit coupling effect, and forms a spin current perpendicular to the interface direction after a current is passed through, wherein electrons in one spin polarization direction migrate upward, and electrons in another spin polarization direction migrate downward;

[0009] A magnetic tunnel junction is located on the SOT effect layer, and a free layer of the magnetic tunnel junction is adjacent to the SOT effect layer;

[0010] The enhancement layer is used to assist the SOT effect layer in flipping the magnetization direction of the free layer of the magnetic tunnel junction, and the enhancement layer is a composite layer structure, including:

[0011] Conductive layer;

[0012] An insulator layer located below the conductive layer, and / or a tunneling isolation layer located above the conductive layer, wherein the insulator layer is used to form an interface built-in electric field with the adjacent substrate and conductive layer to change the spin polarization direction of electrons migrating downward, and the tunneling isolation layer is used to separate electrons with opposite spin polarization directions.

[0013] Optionally, the conductive layer is made of a metal material with high electrical conductivity.

[0014] Optionally, the insulator layer is made of an insulating material having a higher Fermi level than that of the conductive layer, or a non-conductive ferroelectric material.

[0015] Optionally, the work function of the insulator layer is lower than the work function of the conductive layer, and the difference in work function is greater than or equal to 5 eV;

[0016] Alternatively, the insulator layer has a built-in electric field.

[0017] Optionally, the tunneling isolation layer is made of an oxide or a two-dimensional material having a quantum tunneling effect.

[0018] Optionally, the SOT effect layer is a heavy metal layer.

[0019] Optionally, it further comprises: a first electrode and a second electrode, which are located below the SOT effect layer and are respectively located on both sides of the enhancement layer;

[0020] An insulating medium is filled between the first electrode and the reinforcement layer;

[0021] An insulating medium is filled between the second electrode and the reinforcement layer.

[0022] Optionally, it further comprises: a third electrode and a fourth electrode, which are located above the SOT effect layer and are respectively located on both sides of the magnetic tunnel junction;

[0023] An insulating medium is filled between the third electrode and the magnetic tunnel junction;

[0024] An insulating medium is filled between the fourth electrode and the magnetic tunnel junction.

[0025] Optionally, the magnetic tunnel junction includes a free layer, a barrier layer, a reference layer and a pinned layer stacked from bottom to top.

[0026] In a second aspect, the present invention provides a SOT-MRAM memory, comprising the above-mentioned SOT-MRAM storage unit.

[0027] The SOT-MRAM storage unit and SOT-MRAM memory provided by the present invention, when the enhancement layer includes a conductive layer and a tunneling isolation layer, the spin decomposition of spin-polarized electrons with opposite polarization directions is reduced through the quantum tunneling effect, thereby improving the magnetization reversal efficiency of the free layer. When the enhancement layer includes a conductive layer and an insulator layer, the spin-polarized electrons accumulated at the conductive layer / insulator layer interface are flipped through a strong interface built-in electric field and rebounded back to the SOT effect layer, thereby improving the magnetization reversal efficiency of the free layer, and also realizing magnetization reversal without external magnetic field assistance. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 It is a schematic diagram of the principle of spin cancellation of spin-polarized electrons in the prior art;

[0029] Figure 2 A schematic diagram of the structure of a SOT-MRAM storage unit according to an embodiment of the present invention;

[0030] Figure 3A and Figure 3B for Figure 2 Schematic diagram of the principle of the SOT-MRAM memory cell shown;

[0031] Figure 4 A schematic diagram of the structure of a SOT-MRAM storage unit according to an embodiment of the present invention;

[0032] Figure 5 for Figure 4 Schematic diagram of the principle of the SOT-MRAM memory cell shown;

[0033] Figure 6 A schematic diagram of the structure of a SOT-MRAM storage unit according to an embodiment of the present invention;

[0034] Figure 7 A schematic diagram of the structure of a SOT-MRAM storage unit according to an embodiment of the present invention;

[0035] Figure 8 FIG. 4 is a schematic structural diagram of a SOT-MRAM storage unit according to an embodiment of the present invention. DETAILED DESCRIPTION

[0036] In order to make the purpose, technical scheme and advantages of the embodiments of the present invention clearer, the technical scheme in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention, but it should be understood that these descriptions are only exemplary and are not intended to limit the scope of the present disclosure. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention. In addition, in the following description, the description of well-known structures and technologies is omitted to avoid unnecessary confusion of the concepts of the present disclosure.

[0037] Various structural schematic diagrams according to embodiments of the present disclosure are shown in the accompanying drawings. These figures are not drawn to scale, and some details are magnified and some details may be omitted for the purpose of clear expression. The shapes of various regions and layers shown in the figures and the relative sizes and positional relationships therebetween are only exemplary, and may deviate in practice due to manufacturing tolerances or technical limitations, and those skilled in the art may further design regions / layers with different shapes, sizes, and relative positions according to actual needs.

[0038] In the context of the present disclosure, when a layer / element is referred to as being "on" another layer / element, the layer / element may be directly on the other layer / element or an intervening layer / element may exist therebetween. In addition, if a layer / element is "on" another layer / element in one orientation, the layer / element may be "below" the other layer / element when the orientation is reversed.

[0039] Some embodiments of the present invention are described in detail below in conjunction with the accompanying drawings. In the absence of conflict, the following embodiments and features in the embodiments can be combined with each other.

[0040] Embodiment 1:

[0041] An embodiment of the present invention provides a SOT-MRAM storage unit, such as Figure 2 As shown, the SOT-MRAM storage unit includes: a substrate 101, an enhancement layer 102, a SOT effect layer 103 and a magnetic tunnel junction 104 stacked sequentially from bottom to top on the substrate 101,

[0042] The SOT effect layer 103 has a strong spin-orbit coupling effect. When a current is applied, a spin current perpendicular to the interface direction is formed, that is, electrons with opposite spin polarization directions are separated, and electrons in one spin polarization direction migrate upward, while electrons in the other spin polarization direction migrate downward.

[0043] The enhancement layer 102 is used to assist the SOT effect layer 103 in flipping the magnetization direction of the free layer of the magnetic tunnel junction 104. The enhancement layer 102 is a composite layer structure. The enhancement layer of this embodiment includes:

[0044] Conductive layer 1022;

[0045] The insulator layer 1021 is located below the conductive layer 1022 . The insulator layer 1021 is used to form an interface built-in electric field with the adjacent substrate 101 and the conductive layer 1022 , so as to change the spin polarization direction of electrons migrating downward.

[0046] Further, the materials and characteristics of each layer are described in detail as follows:

[0047] The resistivity of the conductive layer 1022 is lower than that of the SOT effect layer 103, so a metal material with high conductivity is selected for the conductive layer 1022. For example, the conductive layer 1022 includes but is not limited to Ag, Al, Au, Cu, Mg, Ir, Ni, Zn, Co, Fe, etc. or their alloys.

[0048] Furthermore, the conductive layer 1022 and the SOT effect layer 103 have similar high work functions, which are greater than or equal to 4 eV, and the difference between the work functions of the conductive layer 1022 and the SOT effect layer 103 is less than or equal to 1.5 eV.

[0049] The insulator layer 1021 is made of an insulating material having a higher Fermi level than the selected conductive layer 1022, or a non-conductive ferroelectric material. The insulating material having a higher Fermi level than the conductive layer includes, but is not limited to, MgO, Al2O3, HfO2, TiO2, AlTiO3, Ga2O3, MnS, Nd2S3, La2O3, Nd2O3, Pr2O3, Sm2O3, SrTiO3, Yb2O3, ZnO, ZrO2, etc. The selectable ferroelectric materials include lead magnesium niobate-lead titanate (PMN-PT), lead zirconate titanate (PZT), barium titanate (BaTiO3), In2Se3, CuInP2S6, MX2, etc., wherein M is one of W and Mo, and X is one of S, Se, and Te.

[0050] Furthermore, the work function of the insulator layer 1021 is lower than the work function of the conductive layer 1022 , and the difference in work function is greater than or equal to 5 eV; or, the insulator layer 1021 has a built-in electric field.

[0051] The SOT effect layer 103 has a large spin Hall angle and can be a heavy metal layer. The material includes but is not limited to one or more compounds or alloys of W, Ta, Pt, Hf, Mo, Ir, CuBi, CuIr, Au, AuW and elements doped with O, N, Si, TiO2, Ti, Cr, V, Cu, MgO, etc.

[0052] Figure 3A and Figure 3BThe schematic diagram of the principle of the SOT-MRAM storage unit of an embodiment of the present invention is shown, and the enhancement layer includes an insulator layer and a conductive layer from bottom to top. Figure 3A The schematic diagram of the spin current distribution and direction in the cross section of the enhancement layer and SOT effect layer along the a direction is shown. Figure 3B The schematic diagram of the spin current distribution and direction in the cross section of the enhancement layer and SOT effect layer along the b direction is shown. Figure 3A As shown, the current J c After passing into the SOT effect layer along the a direction, due to the spin-orbit coupling effect, the current is converted into spin current, and the electrons with opposite spin polarization directions are separated. The electrons in one spin polarization direction (vertical to the paper surface and outward) migrate upward to the free layer / SOT effect layer interface. The electrons at the SOT effect layer / free layer interface transfer the spin momentum to the free layer, causing the magnetization of the free layer to flip and write information. The electrons in the other spin polarization direction (vertical to the paper surface and inward) migrate downward to the SOT effect layer / conductive layer interface. Since the resistivity of the conductive layer is lower than that of the SOT effect layer, the electrons at the SOT effect layer / conductive layer interface enter the conductive layer and continue to migrate downward to the conductive layer / insulator layer interface. Due to the existence of a strong interface built-in electric field at the interface of the conductive layer / insulator layer and the interface built-in electric field of the insulator layer / substrate, or the existence of a strong built-in electric field in the insulator layer, the spin polarization direction of the electrons at the interface of the conductive layer / insulator layer is reversed, and the electron spin polarization direction has a vertical component perpendicular to the direction of the conductive layer / insulator layer interface. The electrons are rebounded by the conductive layer / insulator layer interface, and the migration direction is changed to migrate upward. Some electrons pass through the conductive layer / SOT effect layer interface and enter the SOT effect layer, thereby improving the efficiency of the SOT effect layer spin current on the magnetization reversal of the free layer. Moreover, since the electrons rebounding back to the SOT effect layer have a vertical spin component, the symmetry is broken to achieve controllable reversal of the magnetization direction, and the magnetization reversal of the free layer without the assistance of an external magnetic field can be achieved.

[0053] In order to facilitate the understanding of the technical solution, the relationship between the current direction, the spin polarization direction and the polarized electron migration direction (also referred to as the spin current direction) is further explained.

[0054] The direction of current is the direction in which positive charges move, and the direction in which electrons move is opposite to the direction of current.

[0055] The direction of electron movement, spin polarization direction and polarized electron migration direction can be expressed by the right-hand rule. The four fingers of the right hand point in the direction of electron movement. The four fingers are bent and clenched into a fist in the direction of electron spin polarization. The direction pointed by the thumb is the direction of polarized electron migration.

[0056] When the current direction is opposite, the electrons with the same spin polarization direction will migrate in opposite directions.

[0057] In this embodiment, suitable insulator layer and conductive layer materials are selected so that the higher the built-in electric field at the interface of the substrate / insulator layer and the insulator layer / conductive layer, or the stronger the built-in electric field in the insulator layer, the higher the probability of electron spin flipping, and the better the effect of achieving magnetization flipping without the assistance of an external magnetic field.

[0058] Embodiment 2:

[0059] An embodiment of the present invention provides a SOT-MRAM storage unit, such as Figure 4 As shown, the SOT-MRAM storage unit includes: a substrate 201, an enhancement layer 202, a SOT effect layer 203 and a magnetic tunnel junction 204 stacked sequentially from bottom to top on the substrate 201,

[0060] The SOT effect layer 203 has a strong spin-orbit coupling effect. When current is applied, electrons with opposite spin polarization directions are formed. The electrons with one spin polarization direction migrate upward, and the electrons with the other spin polarization direction migrate downward.

[0061] The enhancement layer 202 is used to assist the SOT effect layer 203 in flipping the magnetization direction of the free layer of the magnetic tunnel junction 204. The enhancement layer 202 is a composite layer structure. The enhancement layer of this embodiment includes:

[0062] Conductive layer 2021;

[0063] The tunneling isolation layer 2022 is located above the conductive layer 2021 , and the tunneling isolation layer 2022 is used to separate electrons with opposite spin polarization directions.

[0064] Further, the materials and characteristics of each layer are described in detail as follows:

[0065] The resistivity of the conductive layer 2021 is lower than that of the SOT effect layer 203, and a metal material with high conductivity is selected for the conductive layer 2021. For example, the conductive layer 2021 includes but is not limited to one of Ag, Al, Au, Cu, Mg, Ir, Ni, Zn, Co, Fe, etc. or an alloy thereof.

[0066] The tunneling isolation layer 2022 is selected from oxides with quantum tunneling effect, or two-dimensional materials, etc. Optionally, the oxides include but are not limited to MgO, Al2O3, SiO2, TiO2, TaO2, NiO, HfO2, etc. Optionally, the two-dimensional materials include hexagonal boron nitride h-BN, etc.

[0067] The SOT effect layer 203 has a large spin Hall angle and can be a heavy metal layer. The material includes but is not limited to one or more compounds or alloys of W, Ta, Pt, Hf, Mo, Ir, CuBi, CuIr, Au, AuW and elements doped with O, N, Si, TiO2, Ti, Cr, V, Cu, MgO, etc.

[0068] Figure 5 The schematic diagram of the principle of the SOT-MRAM storage unit of an embodiment of the present invention is shown, and the enhancement layer includes a conductive layer and a tunnel isolation layer from bottom to top. Figure 5 The schematic diagram of the spin current distribution and direction in the cross section of the enhancement layer and SOT effect layer along the a direction is shown. Figure 5 As shown, the current J c After passing into the SOT effect layer along the a direction, due to the spin-orbit coupling effect, the current is converted into spin current, and the electrons with opposite spin polarization directions are separated. The electrons in one spin polarization direction (vertical to the paper surface and outward) migrate upward to the free layer / SOT effect layer interface. The electrons at the SOT effect layer / free layer interface transfer the spin momentum to the free layer, causing the magnetization of the free layer to flip and write information. The electrons in the other spin polarization direction (vertical to the paper surface and inward) migrate downward to the SOT effect layer / tunneling isolation layer interface. Due to the quantum tunneling effect, a very small part of the electrons at the SOT effect layer / tunneling isolation layer interface are rebounded back to the SOT effect layer, and most of them pass through the tunneling isolation layer into the lower conductive layer. In this way, due to the isolation of the tunneling isolation layer, the electrons with opposite spin polarization directions are separated, reducing the probability of spin cancellation of electrons with opposite spin polarization directions, and improving the efficiency of the SOT effect layer spin polarization electrons in flipping the magnetization of the free layer.

[0069] In this embodiment, by changing the thickness of the tunneling isolation layer, the probability of electrons migrating downwards tunneling through the tunneling isolation layer can be adjusted, thereby adjusting the influence of the conductive layer on the current shunting effect in the SOT effect layer.

[0070] Embodiment three:

[0071] An embodiment of the present invention provides a SOT-MRAM storage unit, such as Figure 6 As shown, the SOT-MRAM storage unit includes: a substrate 301, an enhancement layer 302, a SOT effect layer 303 and a magnetic tunnel junction 304 stacked sequentially from bottom to top on the substrate 301,

[0072] The SOT effect layer 303 has a strong spin-orbit coupling effect. When current is applied, electrons with opposite spin polarization directions are formed. The electrons with one spin polarization direction migrate upward, and the electrons with the other spin polarization direction migrate downward.

[0073] The enhancement layer 302 is used to assist the SOT effect layer 303 in flipping the magnetization direction of the free layer of the magnetic tunnel junction 304. The enhancement layer 302 is a composite layer structure. The enhancement layer of this embodiment includes:

[0074] Conductive layer 3022;

[0075] An insulator layer 3021 located below the conductive layer 3022, the insulator layer 3021 is used to form an interface built-in electric field with the adjacent substrate 301 and the conductive layer 3022, so as to change the spin polarization direction of electrons migrating downward;

[0076] And, a tunneling isolation layer 3023 is located above the conductive layer 3022, and the tunneling isolation layer 3023 is used to separate electrons with opposite spin polarization directions.

[0077] Furthermore, regarding the materials and characteristics of each layer, reference may be made to the descriptions of Example 1 and Example 2, which will not be repeated here.

[0078] The principle of the SOT-MRAM storage unit of the embodiment of the present invention can be referred to Figure 3A , 3B and Figure 5 , the SOT effect layer has a strong spin-orbit coupling effect, and the current J c After that, the current is converted into a spin current, in which the electrons in one spin polarization direction (perpendicular to the paper surface and outward) migrate to the top of the SOT effect layer (the direction of the SOT effect layer / free layer interface), and the electrons in the other spin polarization direction (perpendicular to the paper surface and inward) migrate to the bottom of the SOT effect layer (the direction of the SOT effect layer / tunneling isolation layer interface). The electrons at the SOT effect layer / free layer interface transfer the spin momentum to the free layer, causing the magnetization of the free layer to flip and write information; the electrons at the SOT effect layer / tunneling isolation layer interface enter the lower conductive layer due to the quantum tunneling effect, so that the electrons with opposite spin polarization directions at the upper and lower interfaces of the SOT effect layer are separated from each other, reducing the probability of spin cancellation. The electrons that pass through the tunnel isolation layer and enter the conductive layer are affected by the built-in electric field at the interface of the insulator layer / conductive layer and the substrate / insulator layer, or are affected by the built-in electric field of the insulator layer, and their spin polarization direction changes, and they bounce upward at the insulator layer / conductive layer interface. Some of the electrons whose spin polarization direction has changed pass through the tunnel isolation layer upward and enter the SOT effect layer, transferring the spin momentum to the free layer, thereby improving the magnetization reversal efficiency of the free layer. Moreover, the spin polarization direction of the electrons whose spin polarization direction has changed has components perpendicular to the SOT effect layer / free layer interface direction and parallel to the SOT effect layer / free layer interface direction, thereby realizing magnetization reversal of the free layer without the assistance of an external magnetic field.

[0079] In this embodiment, the thickness of the insulator layer 3021 is 0 nm-100 nm, the thickness of the conductive layer 3022 is 0.2 nm-5 nm, the thickness of the tunneling isolation layer 3023 is 0 nm-5 nm, and the thickness of the SOT effect layer 303 is 0.2 nm-10 nm.

[0080] By adjusting the thickness of the insulator layer, conductive layer, tunnel isolation layer and SOT effect layer, the probability of spin flipping is higher, and electrons with changed spin polarization direction can more easily reach the SOT effect layer / free layer interface, thereby improving the efficiency of free layer magnetization flipping and achieving better magnetization flipping effect without external magnetic field assistance.

[0081] In the above embodiments, the magnetic tunnel junction (104, 204 or 304) includes a free layer, a barrier layer, a reference layer and a pinned layer, and the free layer is adjacent to the SOT effect layer. The free layer and the reference layer have a perpendicular magnetization direction (PMA) or an in-plane magnetization direction (IMA) at the same time. The size of the magnetic tunnel junction is smaller than the size of the SOT effect layer. The material of the free layer and the reference layer can be any one of Co, Fe, Ni, B, Pt or an alloy of two or more thereof, and a multilayer film formed by a combination of the above elements or alloys and one or more of Co, Fe, Ni, Pt, Pd, Mo, W, Ir, Ta, Ru, Nb, Hf, and the material of the barrier layer can be any one of MgO, MgAl2O4, Al2O3, Gd2O3, HfO2 or a combination of two or more thereof.

[0082] The top view morphology of the magnetic tunnel junction includes but is not limited to a circle, an ellipse, a rectangle, etc. The etching process of the magnetic tunnel junction is terminated at the SOT effect layer.

[0083] Further, in one embodiment, if Figure 7 As shown, in Figure 6 Based on the SOT-MRAM storage unit shown in FIG. 1 , the SOT-MRAM storage unit further includes: a first electrode 305 and a second electrode 306, which are located below the SOT effect layer and on both sides of the enhancement layer, respectively. In this structure, the size of the enhancement layer is smaller than the size of the SOT effect layer. An insulating medium is filled between the first electrode 305 and the enhancement layer 302; an insulating medium is filled between the second electrode 306 and the enhancement layer 302. The materials of the insulating medium include SiO2, Si3N4, SiO x N y 、Al2O3、HfO2、HfSiO x , La2O3, etc. The material of the electrode is selected from any one of Cu, Ag, Au, Al, Ti, and W.

[0084] Further, in one embodiment, if Figure 8 As shown, in Figure 6Based on the SOT-MRAM storage unit shown in FIG. 1 , the SOT-MRAM storage unit further includes: a third electrode 307 and a fourth electrode 308, which are located above the SOT effect layer and on both sides of the magnetic tunnel junction, respectively. The size of the enhancement layer under this structure can be equal to the size of the SOT effect layer. An insulating medium is filled between the third electrode 307 and the magnetic tunnel junction 304; an insulating medium is filled between the fourth electrode 308 and the magnetic tunnel junction 304. The materials of the insulating medium include SiO2, Si3N4, SiO x N y 、Al2O3、HfO2、HfSiO x , La2O3, etc. The material of the electrode is selected from any one of Cu, Ag, Au, Al, Ti, and W.

[0085] Another embodiment of the present invention further provides a SOT-MRAM memory, comprising the SOT-MRAM storage unit of the above embodiment.

[0086] In the above description, the technical details of the patterning and etching of each layer are not described in detail. However, those skilled in the art should understand that various technical means can be used to form layers, regions, etc. of desired shapes. In addition, in order to form the same structure, those skilled in the art can also design methods that are not completely the same as the methods described above. In addition, although the various embodiments are described above separately, this does not mean that the measures in the various embodiments cannot be used in combination to advantage.

[0087] The above is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Any changes or substitutions that can be easily thought of by a person skilled in the art within the technical scope disclosed by the present invention should be included in the protection scope of the present invention. Therefore, the protection scope of the present invention should be based on the protection scope of the claims.

Claims

1. A SOT-MRAM storage cell, characterized in that: include: substrate; a reinforcing layer, located on the substrate; A SOT effect layer, located on the enhancement layer, wherein the SOT effect layer has a strong spin-orbit coupling effect, and forms a spin current perpendicular to the interface direction after a current is passed through, wherein electrons in one spin polarization direction migrate upward, and electrons in another spin polarization direction migrate downward; A magnetic tunnel junction is located on the SOT effect layer, and a free layer of the magnetic tunnel junction is adjacent to the SOT effect layer; The enhancement layer is used to assist the SOT effect layer in flipping the magnetization direction of the free layer of the magnetic tunnel junction, and the enhancement layer is a composite layer structure, including: Conductive layer; An insulator layer located below the conductive layer, and / or a tunneling isolation layer located above the conductive layer, wherein the insulator layer is used to form an interface built-in electric field with the adjacent substrate and conductive layer to change the spin polarization direction of electrons migrating downward, and the tunneling isolation layer is used to separate electrons with opposite spin polarization directions.

2. The SOT-MRAM memory cell according to claim 1, characterized in that: The conductive layer is made of a metal material with high electrical conductivity.

3. The SOT-MRAM memory cell according to claim 1, characterized in that: The insulator layer is made of an insulating material having a higher Fermi level than the conductive layer, or a non-conductive ferroelectric material.

4. The SOT-MRAM memory cell according to claim 1, characterized in that: The work function of the insulator layer is lower than the work function of the conductive layer, and the difference in work function is greater than or equal to 5 eV; Alternatively, the insulator layer has a built-in electric field.

5. The SOT-MRAM memory cell according to claim 1, characterized in that: The tunneling isolation layer is made of an oxide or a two-dimensional material having a quantum tunneling effect.

6. The SOT-MRAM memory cell according to claim 1, characterized in that: The SOT effect layer is a heavy metal layer.

7. The SOT-MRAM memory cell according to claim 1, characterized in that: Also includes: A first electrode and a second electrode are located below the SOT effect layer and are respectively located on two sides of the enhancement layer; An insulating medium is filled between the first electrode and the reinforcement layer; An insulating medium is filled between the second electrode and the reinforcement layer.

8. The SOT-MRAM memory cell according to claim 1, characterized in that: Also includes: A third electrode and a fourth electrode are located above the SOT effect layer and are respectively located on two sides of the magnetic tunnel junction; An insulating medium is filled between the third electrode and the magnetic tunnel junction; An insulating medium is filled between the fourth electrode and the magnetic tunnel junction.

9. The SOT-MRAM memory cell according to claim 1, characterized in that: The magnetic tunnel junction includes a free layer, a barrier layer, a reference layer, and a pinned layer stacked from bottom to top.

10. A SOT-MRAM memory, characterized in that: The SOT-MRAM memory comprises the SOT-MRAM memory cell according to any one of claims 1 to 9.

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