Magnetic response unit of TMR sensor and vertical TMR sensor

Abstract

The invention discloses a magnetic response unit of a TMR sensor and a vertical TMR sensor, and is applied to the technical field of magnetic sensors. The barrier layer is located on the surface of one side of the fixed layer; the first free layer is positioned on the surface of one side, back to the fixed layer, of the barrier layer; the second free layer is positioned on one side, back to the fixed layer, of the first free layer; the first free layer is ferromagnetic coupled with the second free layer; the saturation magnetization of the second free layer is smaller than that of the first free layer, and the thickness of the second free layer is larger than that of the first free layer. A high TMR structure is formed by the first free layer, the fixed layer and the barrier layer, so that the TMR sensor has high magnetoresistance; and the anisotropic field of the whole free layer formed by the first free layer and the second free layer can be smaller than the anisotropic field independently formed by the first free layer through the second free layer, so that the sensitivity of the TMR sensor is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of magnetic sensors, and in particular to a magnetic response unit of a TMR sensor and a vertical TMR sensor. Background Art

[0002] As an emerging sensor, TMR (tunneling magnetoresistance) sensors are widely used in consumer electronics, industrial electronics and other fields. The sensor uses the tunneling magnetoresistance effect of magnetic multilayer films to detect external magnetic fields, which is mainly manifested in that the resistance of the magnetic multilayer film changes with the size and angle of the magnetic field. Compared with the widely used Hall and AMR (anisotropic magnetoresistance) sensors, it has the advantages of high sensitivity, small size, low power consumption and high resolution.

[0003] The magnetic response unit MTJ (magnetic tunnel junction) of the TMR sensor is usually composed of a reference layer with a fixed magnetization direction, a free layer whose magnetization direction can rotate with the external magnetic field, and a dielectric layer (tunnel layer) between the magnetic layers. When there is no magnetic field, the magnetic moments of the free layer and the reference layer are orthogonal to each other; under the action of an external magnetic field, the angle between the magnetic moments of the free layer and the reference layer changes, and the MTJ resistance value changes.

[0004] The reference layer of most MTJs in existing TMR sensors is based on in-plane pinning, and the magnetic moments of the reference layer and the free layer are parallel to the device surface. This in-plane TMR sensor has the following problems: 1. In-plane pinning relies on the exchange coupling of antiferromagnetic and ferromagnetic materials, and requires high-temperature external magnetic field annealing induction; 2. The size of the MTJ is relatively large, generally in the micron level.

[0005] In addition to the in-plane TMR sensor, there are also perpendicular TMR sensors reported in related literature. In the absence of a magnetic field, the reference layer and the free layer have a magnetic moment parallel to the device surface, and the magnetic moment of the other magnetic layer is perpendicular to the device surface. The response sensitivity of the perpendicular TMR sensor is generally lower than that of the in-plane TMR sensor, because the sensitivity mainly depends on the magnetoresistance and linear range of the MTJ (the linear working response range of the sensor), and it is difficult for conventional perpendicular magnetization MTJ to take both of the above into account.

[0006] Therefore, how to provide a vertical TMR sensor with high magnetoresistance and narrow linear region is an urgent problem to be solved by those skilled in the art. Summary of the invention

[0007] An object of the present invention is to provide a magnetic response unit of a TMR sensor, which can enable the TMR sensor to have a high magnetoresistance and a narrow linear region; another object of the present invention is to provide a vertical TMR sensor with a high magnetoresistance and a narrow linear region.

[0008] In order to solve the above technical problems, the present invention provides a magnetic response unit of a TMR sensor, comprising:

[0009] A fixed layer; the magnetization direction of the fixed layer is perpendicular to the film plane;

[0010] A barrier layer located on a surface of one side of the fixed layer;

[0011] A first free layer is located on a surface of the barrier layer facing away from the fixed layer; the magnetization direction of the first free layer is parallel to the film plane;

[0012] A second free layer is located on a side of the first free layer facing away from the fixed layer; the magnetization direction of the second free layer is parallel to the film plane, and the first free layer is ferromagnetically coupled to the second free layer; the saturation magnetization intensity of the second free layer is smaller than the saturation magnetization intensity of the first free layer, the thickness of the second free layer is larger than the thickness of the first free layer, and the anisotropy field formed by the first free layer and the second free layer is smaller than the anisotropy field formed by the first free layer alone.

[0013] Optionally, the material of the first free layer is any one of the following:

[0014] Co, Fe, Ni, CoB, FeB, NiB, CoFe, NiFe, CoNi, CoFeB.

[0015] Optionally, the material of the second free layer is an alloy formed by a ferromagnetic metal and a non-magnetic metal, the ferromagnetic metal is one or more of Co, Fe, and Ni; the non-magnetic metal is one or more of V, Cr, Nb, Mo, Ta, W, and Al.

[0016] Optionally, the material of the second free layer is an alloy formed by a 3d metal and a 4f metal, the 3d metal is Co and / or Fe; the 4f metal is one or more of Gd, Tb, Dy, Ho, Er, and Tm.

[0017] Optionally, the material of the second free layer is an alloy formed by a ferromagnetic metal and a non-metal, the ferromagnetic metal is one or more of Co, Fe, and Ni, and the non-metal is one or more of Si, N, C, and B.

[0018] Optionally, also include:

[0019] A cover layer is located on a surface of the second free layer facing away from the fixed layer; and perpendicular magnetic anisotropy is generated at an interface between the cover layer and the second free layer.

[0020] Optionally, the material of the covering layer is any one of the following:

[0021] MgO、HfO 2 、MgAlO、AlO x .

[0022] Optionally, a structure inducing layer is further included; the structure inducing layer is located between the first free layer and the second free layer, and the second free layer is grown on the structure inducing layer to form a preset crystal structure.

[0023] Optionally, the fixed layer includes a reference magnetic layer and a synthetic antiferromagnetic structure;

[0024] The synthetic antiferromagnetic structure comprises:

[0025] a first artificial antiferromagnetic magnetic layer;

[0026] an antiferromagnetic coupling layer located on a surface of one side of the first artificial antiferromagnetic magnetic layer;

[0027] A second artificial antiferromagnetic magnetic layer located on a surface of the antiferromagnetic coupling layer facing away from the first artificial antiferromagnetic magnetic layer;

[0028] The reference magnetic layer is located on a surface of the second artificial antiferromagnetic magnetic layer facing away from the first artificial antiferromagnetic magnetic layer;

[0029] The barrier layer is located on a surface of the reference magnetic layer facing away from the first artificial antiferromagnetic magnetic layer.

[0030] The present invention also provides a vertical TMR sensor, comprising the magnetic response unit of the TMR sensor as described in any one of the above items.

[0031] The present invention provides a magnetic response unit of a TMR sensor, comprising: a fixed layer; a magnetization direction of the fixed layer is perpendicular to a film plane; a barrier layer located on one side surface of the fixed layer; a first free layer located on a side surface of the barrier layer facing away from the fixed layer; a magnetization direction of the first free layer is parallel to the film plane; a second free layer located on a side of the first free layer facing away from the fixed layer; a magnetization direction of the second free layer is parallel to the film plane, and the first free layer and the second free layer are ferromagnetically coupled; a saturation magnetization intensity of the second free layer is smaller than a saturation magnetization intensity of the first free layer, a thickness of the second free layer is larger than a thickness of the first free layer, and an anisotropy field formed by the first free layer and the second free layer is smaller than an anisotropy field formed by the first free layer alone.

[0032] By forming a high TMR structure with a first free layer having a high spin polarization rate, a fixed layer and a barrier layer, the TMR sensor has a high magnetoresistance rate; and by having a second free layer with a lower saturation magnetization intensity but a very thick thickness, the anisotropy field of the free layer formed by the first free layer and the second free layer as a whole can be made smaller than the anisotropy field formed by the first free layer alone, thereby reducing the linear region of the TMR sensor and improving the sensitivity of the TMR sensor.

[0033] The embodiment of the present invention further provides a vertical TMR sensor, which also has the above-mentioned beneficial effects, and will not be described in detail here. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] In order to more clearly illustrate the embodiments of the present invention or the technical solutions of the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0035] Figure 1 A schematic structural diagram of a magnetic response unit of a TMR sensor provided by an embodiment of the present invention;

[0036] Figure 2 This is a curve diagram showing the variation of saturation magnetization intensity with V component ratio in FeV alloy;

[0037] Figure 3 A schematic structural diagram of a magnetic response unit of a first specific TMR sensor provided in an embodiment of the present invention;

[0038] Figure 4 A schematic structural diagram of a magnetic response unit of a second specific TMR sensor provided in an embodiment of the present invention;

[0039] Figure 5 This is a schematic structural diagram of a magnetic response unit of a third specific TMR sensor provided in an embodiment of the present invention.

[0040] In the figure: 1. fixed layer, 11. reference magnetic layer, 12. first artificial antiferromagnetic magnetic layer, 13. antiferromagnetic coupling layer, 14. second artificial antiferromagnetic magnetic layer, 2. barrier layer, 3. first free layer, 4. second free layer, 5. cover layer, 6. structure induction layer. DETAILED DESCRIPTION

[0041] The core of the present invention is to provide a magnetic response unit of a TMR sensor. In the prior art, for a perpendicular TMR sensor, its response sensitivity is generally lower than that of an in-plane TMR sensor, because the sensitivity mainly depends on the magnetoresistance and linear region range of the MTJ (the linear working response range of the sensor), and it is difficult for a conventional perpendicular magnetization MTJ to take both of the above into account.

[0042] The magnetic response unit of a TMR sensor provided by the present invention comprises: a fixed layer; the magnetization direction of the fixed layer is perpendicular to the film plane; a barrier layer located on one surface of the fixed layer; a first free layer located on the surface of the barrier layer on the side facing away from the fixed layer; the magnetization direction of the first free layer is parallel to the film plane; a second free layer located on the side of the first free layer facing away from the fixed layer; the magnetization direction of the second free layer is parallel to the film plane, and the first free layer and the second free layer are ferromagnetically coupled; the saturation magnetization intensity of the second free layer is smaller than the saturation magnetization intensity of the first free layer, the thickness of the second free layer is larger than the thickness of the first free layer, and the anisotropy field formed by the first free layer and the second free layer is smaller than the anisotropy field formed by the first free layer alone.

[0043] By forming a high TMR structure with a first free layer having a high spin polarization rate, a fixed layer and a barrier layer, the TMR sensor has a high magnetoresistance rate; and by having a second free layer with a lower saturation magnetization intensity but a very thick thickness, the anisotropy field of the free layer formed by the first free layer and the second free layer as a whole can be made smaller than the anisotropy field formed by the first free layer alone, thereby reducing the linear region of the TMR sensor and improving the sensitivity of the TMR sensor.

[0044] In order to enable those skilled in the art to better understand the scheme of the present invention, the present invention is further described in detail below in conjunction with the accompanying drawings and specific implementation methods. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all of the embodiments. 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.

[0045] Please refer to Figure 1 as well as Figure 2 , Figure 1 A schematic structural diagram of a magnetic response unit of a TMR sensor provided by an embodiment of the present invention; Figure 2 This is a curve showing the variation of saturation magnetization with V component ratio in FeV alloy.

[0046] See also Figure 1In an embodiment of the present invention, a magnetic response unit of a TMR sensor includes: a fixed layer 1; a magnetization direction of the fixed layer 1 is perpendicular to a film plane; a barrier layer 2 located on one side surface of the fixed layer 1; a first free layer 3 located on a side surface of the barrier layer 2 facing away from the fixed layer 1; a magnetization direction of the first free layer 3 is parallel to the film plane; a second free layer 4 located on a side of the first free layer 3 facing away from the fixed layer 1; a magnetization direction of the second free layer 4 is parallel to the film plane, and the first free layer 3 is ferromagnetically coupled with the second free layer 4; a saturation magnetization intensity of the second free layer 4 is smaller than a saturation magnetization intensity of the first free layer 3, a thickness of the second free layer 4 is larger than a thickness of the first free layer 3, and an anisotropy field formed by the first free layer 3 and the second free layer 4 is smaller than an anisotropy field formed by the first free layer 3 alone.

[0047] The above-mentioned fixed layer 1 is also generally referred to as a reference layer. The magnetization direction of the reference layer is fixed, and the magnetization direction of the fixed layer 1 does not flip when the device is working. In this embodiment, the magnetization direction of the fixed layer 1 is perpendicular to the film plane, that is, the magnetization direction of the fixed layer 1 is specifically distributed in the vertical direction, and the subsequent magnetization direction of the free layer will be distributed in the horizontal direction. The above-mentioned film plane is the plane where the various film layers constituting the magnetic response unit in this embodiment are located. The specific structure of the fixed layer 1 will be described in detail in the following invention embodiments, and will not be repeated here.

[0048] The barrier layer 2 is located on one side of the fixed layer 1. The material of the barrier layer 2 is usually an insulating material. In this embodiment, the material of the barrier layer 2 is usually selected from MgO, HfO 2 , MgAlO and AlO x In this embodiment, MgO is generally selected as the material of the barrier layer 2. Of course, in this embodiment, there is no specific limitation on the material of the barrier layer 2, which depends on the specific situation.

[0049] In this embodiment, the structure located on the side of the barrier layer 2 facing away from the fixed layer 1 is a free layer. In this embodiment, the free layer includes a first free layer 3 and a second free layer 4, wherein the first free layer 3 is located on the surface of the barrier layer 2 facing away from the fixed layer 1, that is, the barrier layer 2 is located between the fixed layer 1 and the first free layer 3. The magnetization direction of the first free layer 3 is parallel to the film plane, that is, the magnetization direction of the first free layer 3 is specifically distributed in the horizontal direction. The first free layer 3 needs to have a high spin polarization rate, so that the fixed layer 1, the barrier layer 2 and the first free layer 3 are combined to form a high TMR structure, which usually needs to meet TMR ≥ 150%, so that the TMR sensor has a high magnetoresistance.

[0050] Specifically, the material of the first free layer 3 is usually any one of the following: Co, Fe, Ni, CoB, FeB, NiB, CoFe, NiFe, CoNi, CoFeB. In this embodiment, CoFeB is specifically selected as the material of the first free layer 3. Since the first free layer 3 is specifically in contact with the barrier layer 2, CoFeB is selected as the material of the first free layer 3, and MgO is selected as the material of the barrier layer 2. Based on the good interface characteristics of the MgO / CoFeB system, it can be ensured that the MTJ has a good TMR, TMR>=150%. Of course, in this embodiment, there is no specific limitation on the material of the first free layer 3, which depends on the specific situation.

[0051] The second free layer 4 is located on the side of the first free layer 3 facing away from the fixed layer 1, and the second free layer 4 needs to be ferromagnetically coupled with the first free layer 3. In this embodiment, the magnetization direction of the second free layer 4 also needs to be parallel to the film surface, and because the second free layer 4 is ferromagnetically coupled with the first free layer 3, the magnetization directions of the two are substantially the same. In this embodiment, the saturation magnetization intensity of the second free layer 4 needs to be smaller than the saturation magnetization intensity of the first free layer 3, and the thickness of the second free layer 4 needs to be greater than the thickness of the first free layer 3, so that the anisotropy field of the free layer formed by the combination of the first free layer 3 and the second free layer 4 is smaller than the anisotropy field formed by the first free layer 3 alone. At this time, compared with only setting the first free layer 3, the anisotropy field of the free layer can be reduced by additionally setting the second free layer 4, thereby obtaining a narrower linear region and ensuring that the TMR sensor has sufficient sensitivity.

[0052] Generally, the thickness of the second free layer 4 needs to be much greater than that of the first free layer 3. The thickness usually needs to be such that the saturation magnetization intensity of the second free layer 4 is lower than that of the first free layer 3. The magnetization direction of the whole free layer is mainly affected by the second free layer 4, so that the anisotropy field H of the whole free layer is k Approximately equal to the saturation magnetization M of the second free layer 4 s , that is, μ 0 H k ≈μ 0 M s , where μ 0 is the magnetic permeability of vacuum.

[0053] Specifically, in this embodiment, it is usually necessary to ensure that the saturation magnetic flux density μ of the second free layer 4 is 0 M s <0.5T, thus satisfying μ 0 H k ≈μ 0 M s<0.5T, so that the linear region of the TMR sensor is <±0.5T and the sensitivity is >0.15% / mT.

[0054] Of course, in this embodiment, the thickness of the second free layer 4 can be reduced, but it is necessary to ensure that the anisotropy field formed by the first free layer 3 and the second free layer 4 is smaller than the anisotropy field formed by the first free layer 3 alone, so as to improve the sensitivity of the TMR sensor compared to the linear region of the TMR sensor reduced in the prior art.

[0055] In this embodiment, the material of the second free layer 4 is generally a low saturation magnetization material, and the material of the second free layer 4 can be an alloy formed by a ferromagnetic metal and a non-magnetic metal, wherein the ferromagnetic metal is one or more of Co, Fe, and Ni; the non-magnetic metal is one or more of V, Cr, Nb, Mo, Ta, W, and Al; the material of the second free layer 4 can also be an alloy formed by a 3d metal and a 4f metal, wherein the 3d metal is Co and / or Fe; the 4f metal is one or more of Gd, Tb, Dy, Ho, Er, and Tm; the material of the second free layer 4 can also be an alloy formed by a ferromagnetic metal and a non-metal, wherein the ferromagnetic metal is one or more of Co, Fe, and Ni, and the non-metal is one or more of Si, N, C, and B.

[0056] Specifically, when the material of the second free layer 4 is an alloy formed by a ferromagnetic metal and a non-magnetic metal, it is preferably FeV, wherein the composition ratio of Fe to V is between 4:6 and 6:4; when the material of the second free layer 4 is an alloy formed by a 3d metal and a 4f metal, it is preferably a CoGd alloy; when the material of the second free layer 4 is an alloy formed by a ferromagnetic metal and a non-metal, it is preferably CoFeSiB, wherein the composition ratio of Co, Fe, Si, and B can be 70.5:4.5:15:10,

[0057] In this embodiment, the material of the second free layer 4 is preferably FeV. At this time, the composition ratio of Fe to V in the FeV is preferably 4:6 to 6:4. The curve of the change of saturation magnetization intensity with V composition ratio in FeV alloy can be referred to Figure 2 , I will not go into details here. Figure 2 In, M s is the saturation magnetization, M eff is the effective magnetic moment. Within this composition ratio range, μ of the second free layer 4 can be 0 M s <0.5T, thus ensuring that the TMR device has high sensitivity.

[0058] It should also be noted that, since the saturation magnetization of the second free layer 4 is significantly smaller than the saturation magnetization of the first free layer 3, the anisotropy field H of the free layer is kIt has better robustness to the thickness fluctuation δt caused by the process, that is, the MTJ under this structure has a larger thickness process window. Taking the material of the first free layer 3 as CoFeB and the material of the second free layer 4 as FeV as an example, the following Table 1 compares the results of the anisotropy field and the magnetic layer thickness of the vertical TMR free layer composed of CoFeB and FeV, as follows:

[0059] Table 1. Performance comparison of CoFeB and FeV

[0060] CoFeB FeV <![CDATA[μ 0 M s ]]> 1.5T 0.4T t 2nm 5nm <![CDATA[μ 0 H k ]]> -380mT -373mT <![CDATA[μ 0 δH k (δt=t×5%)]]> -56mT -1.35mT

[0061] Assuming that the thickness t of the free layer film process on a single wafer changes by 5%, when the anisotropy field of the film formed by the two materials is similar (μ 0 H k ~-380mT), with small M s The FeV operating window fluctuates μ 0 δH k Significantly smaller than those with large M s The CoFeB has a larger process window and better controllability when manufacturing a high-sensitivity TMR sensor than the traditional CoFeB vertical TMR sensor.

[0062] A magnetic response unit of a TMR sensor provided by an embodiment of the present invention forms a high TMR structure with a first free layer 3 having a high spin polarization rate, a fixed layer 1, and a barrier layer 2, so that the TMR sensor has a high magnetoresistance rate; and through a second free layer 4 with a lower saturation magnetization intensity but a very thick thickness, the anisotropy field of the free layer formed by the first free layer 3 and the second free layer 4 can be made smaller than the anisotropy field formed by the first free layer 3 alone, thereby reducing the linear region of the TMR sensor and improving the sensitivity of the TMR sensor.

[0063] The specific structure of the magnetic response unit of the TMR sensor provided by the present invention will be described in detail in the following invention embodiments.

[0064] Please refer to Figure 3 , Figure 3 A schematic structural diagram of a magnetic response unit of a first specific TMR sensor provided in an embodiment of the present invention.

[0065] Different from the above-mentioned invention embodiment, the present invention embodiment further defines the structure of the magnetic response unit of the TMR sensor on the basis of the above-mentioned invention embodiment. The rest of the contents have been described in detail in the above-mentioned invention embodiment and will not be repeated here.

[0066] See also Figure 3In the embodiment of the present invention, the magnetic response unit of the TMR sensor further includes: a cover layer 5 located on the surface of the second free layer 4 facing away from the fixed layer 1; the interface between the cover layer 5 and the second free layer 4 generates perpendicular magnetic anisotropy. The effective anisotropy field of the free layer can be adjusted by the perpendicular magnetic anisotropy generated by the cover layer 5. After the cover layer 5 is provided, the effective anisotropy field of the free layer Among them, M s is the saturation magnetization of the second free layer 4, K s is the interface anisotropy between the second free layer 4 and the cover layer 5, and t is the thickness of the second free layer 4. k When <0, the magnetic moment of the second free layer 4 is confined within the film surface. Based on the above formula, by adjusting the thickness of the second free layer 4, the anisotropy field of the second free layer 4 can be further reduced, thereby improving the sensitivity of the TMR sensor.

[0067] In this embodiment, the material of the cover layer 5 is any one of the following: MgO, HfO 2 、MgAlO、AlO x The cover layer 5 made of the above materials can generate perpendicular magnetic anisotropy at the interface in contact with the second free layer 4 .

[0068] The magnetic response unit of a TMR sensor provided in this embodiment can further reduce the anisotropy field of the free layer and improve the sensitivity of the TMR device by providing a cover layer 5.

[0069] The specific structure of the magnetic response unit of the TMR sensor provided by the present invention will be described in detail in the following invention embodiments.

[0070] Please refer to Figure 4 , Figure 4 This is a schematic structural diagram of a magnetic response unit of a second specific TMR sensor provided in an embodiment of the present invention.

[0071] Different from the above-mentioned invention embodiment, the present invention embodiment further defines the structure of the magnetic response unit of the TMR sensor on the basis of the above-mentioned invention embodiment. The rest of the contents have been described in detail in the above-mentioned invention embodiment and will not be repeated here.

[0072] See also Figure 4In the embodiment of the present invention, the magnetic response unit of the TMR sensor further includes a structure induction layer 6; the structure induction layer 6 is located between the first free layer 3 and the second free layer 4, and the second free layer 4 grows on the structure induction layer 6 to form a preset crystal structure. The structure induction layer 6 is used to assist the second free layer 4 in forming a preset crystal structure, thereby expanding the optional range of the second free layer 4 material, reducing the stress generated during the thin film growth process, and improving the device performance.

[0073] Specifically, in this embodiment, the material of the structure induction layer 6 can be selected from any one of the following: non-magnetic elements such as Ir, Mo, Ru, Ta, W, Cr, and Ti. The thickness of the structure induction layer 6 is usually low to prevent the structure induction layer 6 from affecting the ferromagnetic coupling between the first free layer 3 and the second free layer 4.

[0074] The magnetic response unit of a TMR sensor provided by an embodiment of the present invention can expand the optional range of the second free layer 4 material by setting the structure induction layer 6, reduce the stress generated during the film growth process, and improve the device performance.

[0075] The specific structure of the magnetic response unit of the TMR sensor provided by the present invention will be described in detail in the following invention embodiments.

[0076] Please refer to Figure 5 , Figure 5 This is a schematic structural diagram of a magnetic response unit of a third specific TMR sensor provided in an embodiment of the present invention.

[0077] Different from the above-mentioned invention embodiment, the present invention embodiment further defines the structure of the magnetic response unit of the TMR sensor on the basis of the above-mentioned invention embodiment. The rest of the contents have been described in detail in the above-mentioned invention embodiment and will not be repeated here.

[0078] See also Figure 5 In an embodiment of the present invention, the fixed layer 1 includes a reference magnetic layer 11 and a synthetic antiferromagnetic structure; the synthetic antiferromagnetic structure includes: a first artificial antiferromagnetic magnetic layer 12; an antiferromagnetic coupling layer 13 located on one side surface of the first artificial antiferromagnetic magnetic layer 12; a second artificial antiferromagnetic magnetic layer 14 located on the side surface of the antiferromagnetic coupling layer 13 facing away from the first artificial antiferromagnetic magnetic layer 12; the reference magnetic layer 11 is located on the side surface of the second artificial antiferromagnetic magnetic layer 14 facing away from the first artificial antiferromagnetic magnetic layer 12; the barrier layer 2 is located on the side surface of the reference magnetic layer 11 facing away from the first artificial antiferromagnetic magnetic layer 12.

[0079] The synthetic antiferromagnetic structure is used to provide a pinning field, and the reference magnetic layer 11 is a pinned layer, and the two together form a fixed layer 1. The first artificial antiferromagnetic magnetic layer 12 (first SAF) in the synthetic antiferromagnetic structure can be a multi-layer stacked structure of Pt and Co, and the corresponding second artificial antiferromagnetic magnetic layer 14 (second SAF) can also be a multi-layer stacked structure of Pt and Co. The material of the antiferromagnetic coupling layer 13 can be Ir, so the synthetic antiferromagnetic structure formed by the first artificial antiferromagnetic magnetic layer 12, the antiferromagnetic coupling layer 13, and the second artificial antiferromagnetic magnetic layer 14 can be a combination of [Pt / Co]n / Ir / [Pt / Co]m, wherein n is the number of stacked [Pt / Co] structures in the first artificial antiferromagnetic magnetic layer 12, and m is the number of stacked [Pt / Co] structures in the second artificial antiferromagnetic magnetic layer 14. The barrier layer 2 will specifically contact the reference magnetic layer 11.

[0080] Typically, the magnetization directions of the reference magnetic layer 11 , the first artificial antiferromagnetic magnetic layer 12 , and the second artificial antiferromagnetic magnetic layer 14 need to be perpendicular to the film plane, wherein the magnetization directions of the first artificial antiferromagnetic magnetic layer 12 and the second artificial antiferromagnetic magnetic layer 14 are opposite.

[0081] The magnetic response unit of a TMR sensor provided by an embodiment of the present invention can ensure that the magnetism of the device will not be reversed when it is working by providing a reference magnetic layer 11 and a synthetic antiferromagnetic structure to form a fixed layer 1.

[0082] The embodiment of the present invention further provides a vertical TMR sensor, which includes a magnetic response unit of a TMR sensor as provided in any of the above-mentioned embodiments of the invention, that is, the magnetic response unit MTJ of the vertical TMR sensor in this embodiment is the structure provided in the above-mentioned embodiments of the invention. For other structures in the vertical TMR sensor, reference can be made to the prior art, and no further description will be given here.

[0083] Since the vertical TMR sensor of this embodiment uses the magnetic response unit provided by the above-mentioned embodiment of the invention, the vertical TMR sensor can have a high magnetoresistance and a narrow linear region, thereby having a higher sensitivity.

[0084] The various embodiments in this specification are described in a progressive manner, and each embodiment focuses on the differences from other embodiments. The same or similar parts between the various embodiments can be referenced to each other.

[0085] Finally, it should be noted that, in this article, relational terms such as first and second, etc. are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of further restrictions, the elements defined by the sentence "comprise a ..." do not exclude the presence of other identical elements in the process, method, article or device including the elements.

[0086] The magnetic response unit of a TMR sensor and a vertical TMR sensor provided by the present invention are introduced in detail above. Specific examples are used in this article to illustrate the principles and implementation methods of the present invention. The description of the above embodiments is only used to help understand the method of the present invention and its core idea. It should be pointed out that for ordinary technicians in this technical field, without departing from the principle of the present invention, the present invention can also be improved and modified, and these improvements and modifications also fall within the scope of protection of the claims of the present invention.

Claims

1. A magnetic response unit of a TMR sensor, It is characterized in that include: Fixed layer; The magnetization direction of the fixed layer is perpendicular to the film plane; A barrier layer located on a surface of one side of the fixed layer; A first free layer is located on a surface of the barrier layer facing away from the fixed layer; the magnetization direction of the first free layer is parallel to the film plane; A second free layer is located on a side of the first free layer facing away from the fixed layer; the magnetization direction of the second free layer is parallel to the film plane, and the first free layer is ferromagnetically coupled to the second free layer; the saturation magnetization intensity of the second free layer is smaller than the saturation magnetization intensity of the first free layer, the thickness of the second free layer is larger than the thickness of the first free layer, and the anisotropy field formed by the first free layer and the second free layer is smaller than the anisotropy field formed by the first free layer alone.

2. The magnetic response unit of the TMR sensor according to claim 1, It is characterized in that The material of the first free layer is any one of the following: Co, Fe, Ni, CoB, FeB, NiB, CoFe, NiFe, CoNi, CoFeB.

3. The magnetic response unit of the TMR sensor according to claim 2, It is characterized in that The material of the second free layer is an alloy formed by a ferromagnetic metal and a non-magnetic metal, the ferromagnetic metal is one or more of Co, Fe, and Ni; the non-magnetic metal is one or more of V, Cr, Nb, Mo, Ta, W, and Al.

4. The magnetic response unit of the TMR sensor according to claim 2, It is characterized in that The material of the second free layer is an alloy formed by 3d metal and 4f metal, the 3d metal is Co and / or Fe; the 4f metal is one or more of Gd, Tb, Dy, Ho, Er, and Tm.

5. The magnetic response unit of the TMR sensor according to claim 2, It is characterized in that The material of the second free layer is an alloy formed by a ferromagnetic metal and a non-metal, the ferromagnetic metal is one or more of Co, Fe, and Ni, and the non-metal is one or more of Si, N, C, and B.

6. The magnetic response unit of the TMR sensor according to claim 1, It is characterized in that Also includes: a covering layer located on a surface of the second free layer facing away from the fixed layer; The interface between the cap layer and the second free layer generates perpendicular magnetic anisotropy.

7. The magnetic response unit of the TMR sensor according to claim 6, It is characterized in that The material of the covering layer is any one of the following: MgO、HfO 2 、MgAlO、AlO x 。 8. The magnetic response unit of the TMR sensor according to claim 1, It is characterized in that It also includes a structure induction layer; the structure induction layer is located between the first free layer and the second free layer, and the second free layer is grown on the structure induction layer to form a preset crystal structure.

9. The magnetic response unit of the TMR sensor according to claim 1, It is characterized in that The fixed layer includes a reference magnetic layer and a synthetic antiferromagnetic structure; The synthetic antiferromagnetic structure comprises: a first artificial antiferromagnetic magnetic layer; an antiferromagnetic coupling layer located on a surface of one side of the first artificial antiferromagnetic magnetic layer; A second artificial antiferromagnetic magnetic layer located on a surface of the antiferromagnetic coupling layer facing away from the first artificial antiferromagnetic magnetic layer; The reference magnetic layer is located on a surface of the second artificial antiferromagnetic magnetic layer facing away from the first artificial antiferromagnetic magnetic layer; The barrier layer is located on a surface of the reference magnetic layer facing away from the first artificial antiferromagnetic magnetic layer.

10. A vertical TMR sensor, It is characterized in that A magnetic response unit comprising a TMR sensor as claimed in any one of claims 1 to 9.

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