A tunneling magnetoresistance and a manufacturing method thereof

Abstract

The present invention provides a tunnel magnetoresistor and a method for preparing the same. The tunnel magnetoresistor comprises: a first pinned layer; a free layer disposed opposite the first pinned layer; a tunnel barrier layer located between the first pinned layer and the free layer; a pinned layer located between the first pinned layer and the tunnel barrier layer; and a second pinned layer located on the side of the free layer facing away from the tunnel barrier layer. The first pinned layer and the pinned layer form a first pinning field, and the second pinned layer and the free layer form a second pinning field. The directions of the first pinning field and the second pinning field are both parallel to the surface of the first pinned layer and the second pinned layer, and the angle between the directions of the first pinning field and the second pinning field is 70° to 110°. The saturation field of the tunnel magnetoresistor is increased, thereby extending the linear range of the tunnel magnetoresistance.

Description

Technical Field

[0001] The present invention relates to the technical field of magnetic sensors, and in particular to a tunnel magnetoresistance and a manufacturing method thereof. Background Art

[0002] Magnetic sensing technology is widely used in new energy, intelligent transportation, industrial control, smart home appliances, and smart networks. Tunneling Magneto Resistance (TMR), commonly used in the read / write heads of hard drives, is currently gaining widespread adoption.

[0003] Currently, the linear range of commonly used tunnel magnetoresistors (TMRs) is narrow. To improve this range, engineers and technicians need to sputter hard magnetic material blocks next to the tunnel magnetoresistance sensing area during tunnel magnetoresistance processing. The strength of the magnetic field generated by the hard magnetic material blocks is used to adjust the linear range of the tunnel magnetoresistance. Alternatively, the linear range of the tunnel magnetoresistance can be adjusted by installing permanent magnets with different magnetic field strengths.

[0004] While adding a sputtering process to a hard magnetic material block adjacent to the tunnel magnetoresistance sensing area significantly improves the linear range of the tunnel magnetoresistance, it also increases component manufacturing costs. In tunnel magnetoresistance applications, installing permanent magnets and utilizing the magnetic field they generate to improve the linear range of the tunnel magnetoresistance can lead to significant errors in permanent magnet installation and poor product consistency. Summary of the Invention

[0005] Therefore, the technical problem to be solved by the present invention is to overcome the problem in the prior art that the linear range of tunnel magnetoresistance is difficult to effectively improve, thereby providing a tunnel magnetoresistance and a method for manufacturing the same.

[0006] The present invention provides a tunnel magnetoresistance, comprising: a first pinned layer; a free layer arranged opposite to the first pinned layer; a tunnel barrier layer located between the first pinned layer and the free layer; a pinned layer located between the first pinned layer and the tunnel barrier layer; and a second pinned layer located on a side of the free layer facing away from the tunnel barrier layer; the first pinned layer and the pinned layer form a first pinning field, and the second pinned layer and the free layer form a second pinning field, the directions of the first pinning field and the second pinning field are both parallel to the surface opposite to the second pinned layer, and the angle between the direction of the first pinning field and the direction of the second pinning field is 70° to 110°.

[0007] Optionally, the Neel temperature of the material of the first pinned layer is greater than the Neel temperature of the material of the second pinned layer.

[0008] Optionally, the material of the first pinned layer includes an antiferromagnetic PtMn alloy, and the thickness of the first pinned layer is 15 nm to 20 nm.

[0009] Optionally, the material of the second pinned layer includes an antiferromagnetic IrMn alloy, and the thickness of the second pinned layer is 7 nm to 9 nm.

[0010] Optionally, the free layer is a composite structure, comprising a stacked first free sub-layer and a second free sub-layer, wherein the first free sub-layer is located between the second free sub-layer and the tunneling barrier layer.

[0011] Optionally, the free layer further includes: a spacer layer located between the first free sub-layer and the second free sub-layer.

[0012] Optionally, the material of the spacer layer includes Ta, and the thickness of the spacer layer is 0.1 nm to 0.2 nm.

[0013] Optionally, the material of the first free sub-layer includes CoFeB, and the thickness of the first free sub-layer is 2 nm to 2.2 nm; the material of the second free sub-layer includes NiFe or CoFe, and the thickness of the second free sub-layer is 4 nm to 7 nm.

[0014] Optionally, the pinned layer includes a first ferromagnetic layer, a non-ferromagnetic layer, and a second ferromagnetic layer that are stacked, and the first ferromagnetic layer is located between the first pinned layer and the non-ferromagnetic layer.

[0015] Optionally, the material of the first ferromagnetic layer includes CoFe, and the thickness of the first ferromagnetic layer is 1.6nm~2.4nm; the material of the non-ferromagnetic layer includes Ru, and the thickness of the non-ferromagnetic layer is 0.7nm~0.9nm or 1.8nm~2nm; the material of the second ferromagnetic layer includes CoFeB, and the thickness of the second ferromagnetic layer is 2.4nm~2.8nm.

[0016] Optionally, the thickness of the first ferromagnetic layer is 2 nm; the thickness of the non-ferromagnetic layer is 0.8 nm or 1.9 nm; and the thickness of the second ferromagnetic layer is 2.6 nm.

[0017] Optionally, it further includes: a stabilizing layer of ferromagnetic material located on a side of the second pinned layer facing away from the free layer, wherein the stabilizing layer is suitable for increasing the stability of the second pinning field.

[0018] Optionally, the material of the stabilization layer includes NiFe or CoFe, and the thickness of the stabilization layer is 4 nm to 6 nm.

[0019] The present invention also provides a method for preparing a tunnel magnetoresistance, which is used to form the tunnel magnetoresistance of the present invention, comprising the following steps: forming a first pinning layer; forming a pinned layer on one side of the first pinning layer; forming a tunneling barrier layer on the side of the pinned layer facing away from the first pinning layer; forming a free layer on the side of the tunneling barrier layer facing away from the pinned layer; forming a second pinning layer on the side of the free layer facing away from the tunneling barrier layer; the first pinning layer and the pinned layer form a first pinning field, and the second pinning layer and the free layer form a second pinning field, the directions of the first pinning field and the second pinning field are both parallel to the opposite surfaces of the first pinning layer and the second pinning layer, and the angle between the direction of the first pinning field and the direction of the second pinning field is 70° to 110°.

[0020] Optionally, the Neel temperature of the material of the first pinned layer is greater than the Neel temperature of the material of the second pinned layer; the method for preparing the tunnel magnetoresistance also includes: after forming the second pinned layer, performing a first annealing magnetization treatment on the first pinned layer, and the annealing temperature of the first annealing magnetization treatment is not lower than the Neel temperature of the material of the first pinned layer; after the first annealing magnetization treatment, performing a second annealing magnetization treatment on the second pinned layer, and the annealing temperature of the second annealing magnetization treatment is lower than the Neel temperature of the material of the first pinned layer; the angle between the direction of the magnetic field applied by the first annealing magnetization treatment and the direction of the magnetic field applied by the second annealing magnetization treatment is 70°~110°, and both are parallel to the opposite surfaces of the first pinned layer and the second pinned layer.

[0021] Optionally, the method for forming the free layer includes: forming a first free sub-layer on a side of the tunneling barrier layer facing away from the first pinned layer; and forming a second free sub-layer on a side of the first free sub-layer facing away from the tunneling barrier layer.

[0022] Optionally, the method for forming the free layer further includes: forming a spacer layer between the step of forming the first free sub-layer and the step of forming the second free sub-layer.

[0023] The technical solution of the present invention has the following beneficial effects:

[0024] 1. The tunnel magnetoresistance provided by the present invention comprises: a first pinned layer; a free layer arranged opposite to the first pinned layer; a tunneling barrier layer located between the first pinned layer and the free layer; a pinned layer located between the first pinned layer and the tunneling barrier layer; and a second pinned layer located on the side of the free layer facing away from the tunneling barrier layer; the first pinned layer and the pinned layer form a first pinning field, and the second pinned layer and the free layer form a second pinning field, the directions of the first pinning field and the second pinning field are both parallel to the surfaces opposite to each other of the first pinned layer and the second pinned layer, and the angle between the direction of the first pinning field and the direction of the second pinning field is 70° to 110°. Because the direction of the external magnetic field when the tunnel magnetoresistance is operating is parallel to the direction of the pinning field formed by the first pinning layer and the pinned layer, the angle between the pinning field formed by the second pinning layer and the free layer and the direction of the external magnetic field when the tunnel magnetoresistance is operating is 70° to 110°. The tunnel magnetoresistance needs to overcome the additional pinning field formed by the second pinning layer and the free layer in order to make the tunnel magnetoresistance reach a saturated state, thereby increasing the saturation field of the tunnel magnetoresistance and thus increasing the linear range of the tunnel magnetoresistance.

[0025] 2. Furthermore, the Neel temperature of the material of the first pinned layer is greater than the Neel temperature of the material of the second pinned layer. Therefore, during the magnetization of the second pinned layer, the first pinning field can be prevented from being disturbed, which is beneficial to the formation of the second pinning field.

[0026] 3. Furthermore, the spacer layer is located between the first free sub-layer and the second free sub-layer. The spacer layer is helpful in preventing mutual diffusion between the first free sub-layer and the second free sub-layer.

[0027] 4. Furthermore, the material of the second free sublayer includes NiFe or CoFe, and the thickness of the second free sublayer is 4 nm to 7 nm. By adjusting the thickness of the second free sublayer, the saturation field of the tunnel magnetoresistance can be adjusted, thereby adjusting the linear range of the tunnel magnetoresistance.

[0028] 5. Furthermore, the thickness of the first ferromagnetic layer is 2 nm; the thickness of the non-ferromagnetic layer is 0.8 nm or 1.9 nm; and the thickness of the second ferromagnetic layer is 2.6 nm. Under these conditions, the tunnel magnetoresistance has a relatively small coercive force.

[0029] 6. Furthermore, a stabilizing layer of ferromagnetic material is provided on the side of the second pinned layer facing away from the free layer. The pinning field formed by the stabilizing layer and the second pinned layer is conducive to increasing the magnetic field stability of the second pinned layer.

[0030] 7. The present invention provides a method for preparing a tunnel magnetoresistance, wherein a second pinning layer is formed on the side of the free layer facing away from the tunnel barrier layer; the first pinning layer and the pinned layer form a first pinning field, and the second pinning layer and the free layer form a second pinning field. The directions of the first pinning field and the second pinning field are both parallel to the surfaces opposite the first pinning layer and the second pinning layer, and the angle between the directions of the first pinning field and the second pinning field is 70° to 110°. Because the direction of the external magnetic field during operation of the tunnel magnetoresistance is parallel to the direction of the pinning field formed by the first pinning layer and the pinned layer, the angle between the pinning field formed by the second pinning layer and the free layer and the direction of the external magnetic field during operation of the tunnel magnetoresistance is 70° to 110°. The tunnel magnetoresistance needs to overcome the additional pinning field formed by the second pinning layer and the free layer to reach a saturated state, thereby increasing the saturation field of the tunnel magnetoresistance and thereby extending the linear range of the tunnel magnetoresistance.

[0031] 8. Further, a second free sub-layer is formed on the side of the first free sub-layer facing away from the tunnel barrier layer. The saturation field of the tunnel magnetoresistance can be adjusted by adjusting the thickness of the second free sub-layer, thereby adjusting the linear range of the tunnel magnetoresistance.

[0032] 9. Furthermore, a spacer layer is formed between the step of forming the first free sub-layer and the step of forming the second free sub-layer. The spacer layer is beneficial to preventing mutual diffusion between the first free sub-layer and the second free sub-layer. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] In order to more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the specific embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0034] Figures 1 to 13 A schematic structural diagram of a tunnel magnetoresistance formation process according to an embodiment of the present invention;

[0035] Figure 14 A top view of a tunnel magnetoresistance according to an embodiment of the present invention. DETAILED DESCRIPTION

[0036] The technical solution of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the embodiments described are only some embodiments of the present invention, not all embodiments. All other embodiments obtained by ordinary technicians in this field based on the embodiments of the present invention without making any creative efforts shall fall within the scope of protection of the present invention.

[0037] In the description of the present invention, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicating orientations or positional relationships, are based on the orientations or positional relationships shown in the accompanying drawings and are intended solely to facilitate and simplify the description of the present invention. They are not intended to indicate or imply that the devices or components referred to must have, be constructed, or operate in a specific orientation, and therefore should not be construed as limitations on the present invention. Furthermore, the terms "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0038] In the description of the present invention, it should be noted that, unless otherwise expressly specified or limited, the terms "installed," "connected," and "connected" should be understood in a broad sense. For example, they can refer to fixed connections, detachable connections, or integral connections; mechanical connections or electrical connections; direct connections or indirect connections through an intermediate medium; internal connections between two components; wireless connections or wired connections. Those skilled in the art will understand the specific meanings of the above terms in the present invention based on specific circumstances.

[0039] In addition, the technical features involved in the different embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0040] This embodiment provides a method for preparing a tunnel magnetoresistance, comprising the following steps: forming a first pinning layer; forming a pinned layer on one side of the first pinned layer; forming a tunneling barrier layer on a side of the pinned layer facing away from the first pinned layer; forming a free layer on a side of the tunneling barrier layer facing away from the pinned layer; and forming a second pinning layer on a side of the free layer facing away from the tunneling barrier layer; the first pinning layer and the pinned layer form a first pinning field, and the second pinning layer and the free layer form a second pinning field, the directions of the first pinning field and the second pinning field are both parallel to the surfaces opposite to each other of the first pinning layer and the second pinning layer, and the angle between the direction of the first pinning field and the direction of the second pinning field is 70° to 110°.

[0041] Figures 1 to 13 A structural schematic diagram of a tunnel magnetoresistance formation process provided by an embodiment of the present invention.

[0042] Please refer to Figure 1 , providing a substrate 1.

[0043] The substrate 1 can be a silicon substrate or a glass substrate.

[0044] An isolation layer (not shown) is plated on the surface of one side of the substrate 1. The material of the isolation layer is Al2O3 or SiO2. The thickness of the isolation layer is 80nm to 120nm, for example, 80nm, 100nm or 120nm.

[0045] Please refer to Figure 2 , a bottom electrode layer 2 is formed on the surface of the substrate 1 on the side where the isolation layer is plated.

[0046] The bottom electrode layer 2 is made of a conductive material, such as Ru, Au or CuN.

[0047] Please refer to Figure 3 , a seed layer 3 is formed on the surface of the bottom electrode layer 2 facing away from the substrate 1 .

[0048] The seed layer 3 can be a single-layer structure composed of Ta or Ru, a double-layer structure composed of two layers of Ta and Ru respectively, or a stacked structure composed of Ta and Ru stacked in sequence, with the thickness of each layer of Ta or Ru being 5nm to 20nm, for example, 5nm, 10nm, 15nm or 20nm.

[0049] The seed layer 3 reduces the surface roughness of the first pinned layer 4 , which is beneficial to the growth of the first pinned layer 4 film and can also effectively prevent the bottom electrode layer 2 , substrate 1 and external environment from affecting the tunnel magnetoresistance lattice structure.

[0050] Please refer to Figure 4 , a first pinning layer 4 is formed on the surface of the seed layer 3 facing away from the bottom electrode layer 2 .

[0051] The material of the first pinned layer 4 includes an antiferromagnetic PtMn alloy.

[0052] The thickness of the first pinned layer 4 is 15 nm to 20 nm, for example, 15 nm, 17 nm, 18 nm or 20 nm, preferably 17 nm.

[0053] Please refer to Figure 5 A pinned layer 5 is formed on the surface of the first pinning layer 4 facing away from the seed layer 3 .

[0054] In this embodiment, the steps of forming the pinned layer 5 include: forming a first ferromagnetic layer 501 on the surface of the first pinned layer 4 facing away from the seed layer 3; forming a non-ferromagnetic layer 502 on the surface of the first ferromagnetic layer 501 facing away from the first pinned layer 4; and forming a second ferromagnetic layer 503 on the surface of the non-ferromagnetic layer 502 facing away from the first ferromagnetic layer 501.

[0055] In one embodiment, the material of the first ferromagnetic layer 501 includes CoFe, and the thickness of the first ferromagnetic layer 501 is 1.6 nm to 2.4 nm, for example, 1.6 nm, 2 nm, or 2.4 nm, preferably 2 nm. In other embodiments, the first ferromagnetic layer 501 may also be a synthetic antiferromagnetic layer structure formed by stacking three layers of CoFe, Ru, and CoFe in sequence.

[0056] In one embodiment, the material of the non-ferromagnetic layer 502 includes Ru, and the thickness of the non-ferromagnetic layer 502 is 0.7 nm to 0.9 nm, for example, 0.7 nm, 0.8 nm, or 0.9 nm, preferably 0.8 nm, or 1.8 nm to 2 nm, for example, 1.8 nm, 1.9 nm, or 2 nm, preferably 1.9 nm.

[0057] In one embodiment, the material of the second ferromagnetic layer 503 includes CoFeB, and the thickness of the second ferromagnetic layer 503 is 2.4 nm to 2.8 nm, for example, 2.4 nm, 2.6 nm, or 2.8 nm, preferably 2.6 nm.

[0058] In a preferred embodiment, the thickness of the first ferromagnetic layer 501 is 2 nm, the thickness of the non-ferromagnetic layer 502 is 0.8 nm or 1.9 nm, and the thickness of the second ferromagnetic layer 503 is 2.6 nm. Under this condition, the tunnel magnetoresistance has a relatively small coercive force.

[0059] Please refer to Figure 6 A tunnel barrier layer 6 is formed on the surface of the pinned layer 5 facing away from the first pinned layer 4 .

[0060] The material of the tunnel barrier layer 6 includes Al 2 O 3 or MgO.

[0061] The thickness of the tunnel barrier layer 6 is 0.5 nm to 1.5 nm, for example, 0.5 nm, 1 nm, 1.2 nm or 1.5 nm.

[0062] Please refer to Figure 7 A first free sub-layer 701 is formed on the surface of the tunnel barrier layer 6 facing away from the pinned layer 5 .

[0063] The material of the first free sub-layer 701 includes CoFeB.

[0064] The thickness of the first free sub-layer 701 is 2 nm to 2.2 nm, for example, 2 nm, 2.1 nm, or 2.2 nm.

[0065] Please refer to Figure 8 A spacer layer 702 is formed on the surface of the first free sub-layer 701 facing away from the tunneling barrier layer 6 .

[0066] The material of the spacer layer 702 includes Ta.

[0067] The thickness of the spacer layer 702 is 0.1 nm to 0.2 nm, for example, 0.1 nm, 0.15 nm, or 0.2 nm.

[0068] The spacer layer 702 is helpful in preventing the mutual diffusion between the first free sub-layer 701 and the second free sub-layer 702. If the thickness of the spacer layer 702 is too small, it is difficult to prevent the mutual diffusion between the first free sub-layer 701 and the second free sub-layer 702. If the thickness of the spacer layer 702 is too large, it is difficult for the pinning field of the second free sub-layer 702 to pass through the spacer layer 702 to pin the first free sub-layer 701, so that the free layer 7 cannot become an integral composite structure.

[0069] Please refer to Figure 9 A second free sub-layer 703 is formed on the surface of the spacer layer 702 facing away from the first free sub-layer 701 .

[0070] The material of the second free sub-layer 703 includes NiFe or CoFe.

[0071] The thickness of the second free sub-layer 703 is 4 nm to 7 nm, for example, 4 nm, 5 nm, 6 nm or 7 nm.

[0072] In this embodiment, when the thickness of the second free sub-layer 703 is 4nm, the saturation field of the second free sub-layer 703 is 250Gs; when the thickness of the second free sub-layer 703 is 7nm, the saturation field of the second free sub-layer 703 is 160Gs. The thickness of the second free sub-layer 703 can be adjusted according to needs, thereby adjusting the saturation field size of the tunnel magnetoresistance, and then adjusting the linear range of the tunnel magnetoresistance.

[0073] The free layer in this embodiment is a composite free layer, and the first free sub-layer 701 , the spacer layer 702 , and the second free sub-layer 703 are combined to form the free layer 7 .

[0074] In other embodiments, the free layer is a single-layer structure, and the material of the free layer includes CoFeB.

[0075] Please refer to Figure 10 A second pinned layer 8 is formed on the surface of the free layer 7 facing away from the tunneling barrier layer 6 .

[0076] The material of the second pinning layer 8 includes IrMn.

[0077] The thickness of the second pinning layer 8 is 7 nm to 9 nm, for example, 7 nm, 8 nm or 9 nm, preferably 8 nm.

[0078] The second pinning layer 8 and the free layer 7 form a second pinning field, and the direction of the second pinning field is parallel to the opposite surfaces of the first pinning layer 4 and the second pinning layer 8. The second pinning layer 8 does not completely pin the free layer 7, so that the magnetic moment direction of the free layer 7 can change with the change of the external magnetic field direction. After the external magnetic field is removed, the magnetic moment direction of the free layer 7 can be restored to the direction of the initial state.

[0079] Please refer to Figure 11 A stabilizing layer 9 is formed on the surface of the second pinned layer 8 facing away from the free layer 7 .

[0080] The material of the stabilization layer 9 includes NiFe or CoFe.

[0081] The thickness of the stabilization layer 9 is 4 nm to 6 nm, for example, 4 nm, 5 nm or 6 nm, preferably 5 nm.

[0082] The stabilizing layer 9 is adapted to increase the stability of the pinning field formed by the second pinning layer 8 and the free layer 7 .

[0083] In other embodiments, the stabilization layer 9 may not be formed.

[0084] Please refer to Figure 12 A covering layer 10 is formed on the surface of the stabilizing layer 9 facing away from the second pinning layer 8 .

[0085] The capping layer 10 may be a single-layer structure composed of Ta or Ru, a double-layer structure composed of two layers of Ta and Ru, or a stacked structure composed of Ta and Ru stacked in sequence. The thickness of each Ta or Ru layer is 5 nm to 10 nm, for example, 5 nm, 6 nm, 8 nm, or 10 nm.

[0086] The cover layer 10 can effectively prevent the tunnel magnetoresistance lattice structure from being affected by the external environment, thereby ensuring the stability of the tunnel magnetoresistance.

[0087] Please refer to Figure 13 A top electrode layer 11 is formed on the surface of the cover layer 10 facing away from the stabilization layer 9 .

[0088] The top electrode layer 11 is made of a conductive material, such as Ru, Au or CuN.

[0089] Next, the first pinned layer 4 is subjected to a first annealing magnetization process.

[0090] The magnetization direction of the first annealing magnetization treatment is parallel to the opposing surface of the first pinned layer 4 and the second pinned layer.

[0091] The first annealing magnetization process and along Figure 14 In other embodiments, the direction of the X axis can also be along Figure 14 The opposite direction of the X axis.

[0092] The magnetic field size of the first annealing magnetization treatment is 8000 Gs to 12000 Gs, for example, it can be 8000 Gs, 10000 Gs or 12000 Gs.

[0093] The annealing temperature of the first annealing magnetization treatment is not lower than the Neel temperature of the material of the first pinned layer 4. In this embodiment, the material of the first pinned layer 4 is PtMn, and the Neel temperature of PtMn is 330°C. The annealing temperature of the first annealing magnetization treatment is 330°C to 350°C. For example, it can be 330°C, 340°C, or 350°C. Applying a Neel temperature not lower than the Neel temperature of the material of the first pinned layer 4 to the first pinned layer 4 can disrupt the microscopic magnetic order within the material of the first pinned layer 4, causing the magnetic field direction of the first pinned layer 4 to be aligned with the magnetization direction.

[0094] After the first annealing magnetization treatment is completed, the direction of the first pinning field formed by the first pinning layer 4 and the pinned layer 5 is parallel to the opposite surface of the first pinning layer 4 and the second pinning layer.

[0095] Next, the second pinned layer 8 is subjected to a second annealing magnetization process.

[0096] Please refer to Figure 14 , Figure 14 A top view of a tunnel magnetoresistance according to an embodiment of the present invention is provided. Figure 14 The angle between the X axis and the Y axis is 70° to 110°, for example, 70°, 80°, 90°, 100° or 110°, preferably 90°. In one embodiment, when the tunnel magnetoresistance is working, the magnetic field direction of the external magnetic field is parallel to the surface opposite to the first pinned layer 4 and the second pinned layer 8 and along Figure 14 In the X-axis direction or along Figure 14 The opposite direction of the X axis.

[0097] Please continue to refer to Figure 14 The magnetization direction of the second annealing magnetization treatment is parallel to the surface of the second pinned layer 8 opposite to the first pinned layer and along Figure 14 In other embodiments, the Y-axis direction may be along Figure 14 The opposite direction of the Y axis.

[0098] The magnetic field size of the second annealing magnetization treatment is 200 Gs to 400 Gs, for example, 200 Gs, 300 Gs or 400 Gs.

[0099] The annealing temperature of the second annealing and magnetization treatment is lower than the Neel temperature of the material of the first pinned layer 4. To avoid affecting the first pinned layer 4 during the second annealing and magnetization process, the annealing temperature of the second annealing and magnetization treatment should not be close to the Neel temperature of the material of the first pinned layer 4. In this example, the Neel temperature of the material of the first pinned layer 4 is 330°C, and the material of the second pinned layer 8 is IrMn, which has a Neel temperature of 270°C. The annealing temperature of the second annealing and magnetization treatment can be 250°C to 280°C. For example, it can be 250°C, 260°C, or 280°C. When the annealing temperature of the second annealing magnetization treatment is lower than the Neel temperature of the material of the second pinned layer 8, it can disrupt the microscopic magnetic order within part of the material of the second pinned layer 8, so that the magnetic field direction of the second pinned layer 8 is partially along the magnetization direction. When the annealing temperature of the second annealing magnetization treatment is equal to or higher than the Neel temperature of the material of the second pinned layer 8, it can disrupt the microscopic magnetic order within the material of the entire second pinned layer 8, so that the magnetic field direction of the entire second pinned layer 8 is along the magnetization direction.

[0100] In this embodiment, the Neel temperature of the material of the first pinned layer 4 is greater than the Neel temperature of the material of the second pinned layer 8. During the second annealing and magnetization process, the annealing temperature of the second annealing and magnetization process is lower than the Neel temperature of the material of the first pinned layer 4. This prevents the magnetic field direction of the first pinned layer from being disturbed during the magnetization of the second pinned layer 8, thereby facilitating the formation of the magnetic field of the second pinned layer.

[0101] After the second annealing magnetization treatment is completed, the second pinning field formed by the second pinning layer 8 and the free layer 7, the directions of the first pinning field and the second pinning field are parallel to the opposite surfaces of the first pinning layer and the second pinning layer, and the angle between the direction of the first pinning field and the direction of the second pinning field is 70° to 110°.

[0102] Because the direction of the external magnetic field when the tunnel magnetoresistance is operating is parallel to the direction of the pinning field formed by the first pinning layer and the pinned layer, the angle between the pinning field formed by the second pinning layer and the free layer and the direction of the external magnetic field when the tunnel magnetoresistance is operating is 70° to 110°. The tunnel magnetoresistance needs to overcome the additional pinning field formed by the second pinning layer and the free layer in order to make the tunnel magnetoresistance reach a saturated state, thereby increasing the saturation field of the tunnel magnetoresistance and thus increasing the linear range of the tunnel magnetoresistance.

[0103] This embodiment provides a tunnel magnetoresistance, please refer to Figure 13, including: a first pinned layer 4; a free layer 7 arranged opposite to the first pinned layer 4; a tunneling barrier layer 6 located between the first pinned layer 4 and the free layer 7; a pinned layer 5 located between the first pinned layer 4 and the tunneling barrier layer 6; a second pinned layer 8 located on the side of the free layer 7 facing away from the tunneling barrier layer 6; the first pinned layer 4 and the pinned layer 5 form a first pinning field, and the second pinned layer 8 and the free layer 7 form a second pinning field, the directions of the first pinning field and the second pinning field are both parallel to the surfaces opposite to each other of the first pinned layer and the second pinned layer, and the angle between the direction of the first pinning field and the direction of the second pinning field is 70° to 110°.

[0104] The tunnel magnetoresistance further includes a substrate 1 , which is located on a side of the first pinning layer 4 facing away from the pinned layer 5 .

[0105] The substrate 1 may be a silicon substrate or a glass substrate.

[0106] An isolation layer (not shown) is plated on the surface of one side of the substrate 1. The material of the isolation layer is Al2O3 or SiO2. The thickness of the isolation layer is 80nm to 120nm, for example, 80nm, 100nm or 120nm.

[0107] A bottom electrode layer 2 is provided on the surface of the substrate 1 on the side where the isolation layer is plated.

[0108] The bottom electrode layer 2 is made of a conductive material, such as Ru, Au or CuN.

[0109] A seed layer 3 is provided on the surface of the bottom electrode layer 2 facing away from the substrate 1 .

[0110] The seed layer 3 can be a single-layer structure composed of Ta or Ru, a double-layer structure composed of two layers of Ta and Ru respectively, or a stacked structure composed of Ta and Ru stacked in sequence, with the thickness of each layer of Ta or Ru being 5nm to 20nm, for example, 5nm, 10nm, 15nm or 20nm.

[0111] The seed layer 3 reduces the surface roughness of the first pinned layer 4 , which is beneficial to the growth of the first pinned layer 4 film and can also effectively prevent the bottom electrode layer 2 , substrate 1 and external environment from affecting the tunnel magnetoresistance lattice structure.

[0112] The material of the first pinned layer 4 includes an antiferromagnetic PtMn alloy.

[0113] The thickness of the first pinned layer 4 is 15 nm to 20 nm, for example, 15 nm, 16 nm, 18 nm or 20 nm.

[0114] The pinned layer 5 includes a stacked first ferromagnetic layer 501 , a non-ferromagnetic layer 502 and a second ferromagnetic layer 503 . The first ferromagnetic layer 501 is located between the first pinned layer 4 and the non-ferromagnetic layer 502 .

[0115] In one embodiment, the material of the first ferromagnetic layer 501 includes CoFe, and the thickness of the first ferromagnetic layer 501 is 1.6 nm to 2.4 nm, for example, 1.6 nm, 2 nm, or 2.4 nm, preferably 2 nm. In other embodiments, the first ferromagnetic layer 501 may also be a synthetic antiferromagnetic layer structure formed by stacking three layers of CoFe, Ru, and CoFe in sequence.

[0116] In one embodiment, the material of the non-ferromagnetic layer 502 includes Ru, and the thickness of the non-ferromagnetic layer 502 is 0.7 nm to 0.9 nm, for example, 0.7 nm, 0.8 nm, or 0.9 nm, preferably 0.8 nm, or 1.8 nm to 2 nm, for example, 1.8 nm, 1.9 nm, or 2 nm, preferably 1.9 nm.

[0117] In one embodiment, the material of the second ferromagnetic layer 503 includes CoFeB, and the thickness of the second ferromagnetic layer 503 is 2.4 nm to 2.8 nm, for example, 2.4 nm, 2.6 nm, or 2.8 nm, preferably 2.6 nm.

[0118] In a preferred embodiment, the thickness of the first ferromagnetic layer 501 is 2 nm, the thickness of the non-ferromagnetic layer 502 is 0.8 nm or 1.9 nm, and the thickness of the second ferromagnetic layer 503 is 2.6 nm. Under this condition, the tunnel magnetoresistance has a relatively small coercive force.

[0119] The material of the tunnel barrier layer 6 includes Al 2 O 3 or MgO.

[0120] The thickness of the tunnel barrier layer 6 is 0.5 nm to 1.5 nm, for example, 0.5 nm, 1 nm, 1.2 nm or 1.5 nm.

[0121] The free layer 7 is a composite structure, and includes a first free sub-layer 701 and a second free sub-layer 703 stacked together.

[0122] The material of the first free sub-layer 701 includes CoFeB.

[0123] The thickness of the first free sub-layer 701 is 2 nm to 2.2 nm, for example, 2 nm, 2.1 nm, or 2.2 nm.

[0124] The material of the second free sub-layer 703 includes NiFe or CoFe.

[0125] The thickness of the second free sub-layer 703 is 4 nm to 7 nm, for example, 4 nm, 5 nm, 6 nm or 7 nm.

[0126] In this embodiment, when the thickness of the second free sub-layer 703 is 4nm, the saturation field of the second free sub-layer 703 is 250Gs; when the thickness of the second free sub-layer 703 is 7nm, the saturation field of the second free sub-layer 703 is 160Gs. The thickness of the second free sub-layer 703 can be adjusted according to needs, thereby adjusting the saturation field size of the tunnel magnetoresistance, and then adjusting the linear range of the tunnel magnetoresistance.

[0127] The free layer 7 further includes a spacer layer 702 located between the first free sub-layer 701 and the second free sub-layer 703 .

[0128] The material of the spacer layer 702 includes Ta.

[0129] The thickness of the spacer layer 702 is 0.1 nm to 0.2 nm, for example, 0.1 nm, 0.15 nm, or 0.2 nm.

[0130] The free layer in this embodiment is a composite free layer, wherein the first free sublayer 701, the spacer layer 702 and the second free sublayer 703 form the free layer 7. The first free sublayer 701 is located between the tunnel barrier layer 6 and the spacer layer 702; the second free sublayer 703 is located between the spacer layer 702 and the second pinned layer 8.

[0131] In other embodiments, the free layer is a single-layer structure, and the material of the free layer includes CoFeB.

[0132] The material of the second pinning layer 8 includes IrMn.

[0133] The thickness of the second pinning layer 8 is 7 nm to 9 nm, for example, 7 nm, 8 nm or 9 nm, preferably 8 nm.

[0134] The tunnel magnetoresistance further includes a stabilizing layer 9 of ferromagnetic material located on the side of the second pinned layer 8 facing away from the free layer 7 . The stabilizing layer 9 is adapted to increase the stability of the pinning field formed by the second pinned layer and the free layer.

[0135] The material of the stabilization layer 9 includes NiFe or CoFe.

[0136] The thickness of the stabilization layer 9 is 4 nm to 6 nm, for example, 4 nm, 5 nm or 6 nm, preferably 5 nm.

[0137] In other embodiments, the tunnel magnetoresistance may not include the stabilization layer 9 .

[0138] A covering layer 10 is further provided on the surface of the stabilization layer 9 facing away from the second pinning layer 8 .

[0139] The capping layer 10 may be a single-layer structure composed of Ta or Ru, a double-layer structure composed of two layers of Ta and Ru, or a stacked structure composed of Ta and Ru stacked in sequence. The thickness of each Ta or Ru layer is 5 nm to 10 nm, for example, 5 nm, 6 nm, 8 nm, or 10 nm.

[0140] The cover layer 10 can effectively prevent the tunnel magnetoresistance lattice structure from being affected by the external environment, thereby ensuring the stability of the tunnel magnetoresistance.

[0141] A top electrode layer 11 is further provided on the surface of the cover layer 10 facing away from the stabilization layer 9 .

[0142] The top electrode layer 11 is made of a conductive material, such as Ru, Au or CuN.

[0143] Because the direction of the external magnetic field when the tunnel magnetoresistance is operating is parallel to the direction of the pinning field formed by the first pinning layer and the pinned layer, the angle between the pinning field formed by the second pinning layer and the free layer and the direction of the external magnetic field when the tunnel magnetoresistance is operating is 70° to 110°. The tunnel magnetoresistance needs to overcome the additional pinning field formed by the second pinning layer and the free layer in order to make the tunnel magnetoresistance reach a saturated state, thereby increasing the saturation field of the tunnel magnetoresistance and thus increasing the linear range of the tunnel magnetoresistance.

[0144] Obviously, the above embodiments are merely examples for clarity of explanation and are not intended to limit the implementation methods. Those skilled in the art will readily appreciate that other variations or modifications based on the above descriptions are possible. It is not necessary and impossible to enumerate all implementation methods here. Obvious variations or modifications arising therefrom remain within the scope of protection of the present invention.

Claims

1. A tunnel magnetoresistance, characterized in that include: a first pinned layer, wherein the material of the first pinned layer includes an antiferromagnetic PtMn alloy, the Neel temperature of PtMn is 330° C., the first pinned layer is subjected to a first annealing and magnetization treatment, the annealing temperature of the first annealing and magnetization treatment is 330° C. to 350° C., and the magnetic field size of the first annealing and magnetization treatment is 8000 Gs to 12000 Gs; a free layer disposed opposite the first pinned layer, the free layer being a composite structure, the free layer comprising a first free sublayer and a second free sublayer stacked together, the free layer further comprising: a spacer layer located between the first free sublayer and the second free sublayer, the first free sublayer comprising CoFeB, the second free sublayer having a thickness of 4 nm to 7 nm, the spacer layer comprising Ta, and having a thickness of 0.15 nm to 0.2 nm; a tunneling barrier layer located between the first pinned layer and the free layer, and a first free sub-layer located between the second free sub-layer and the tunneling barrier layer; a pinned layer located between the first pinning layer and the tunneling barrier layer; a second pinned layer located on a side of the free layer facing away from the tunneling barrier layer, wherein the material of the second pinned layer includes an antiferromagnetic IrMn alloy, the Neel temperature of IrMn is 270° C., the second pinned layer undergoes a second annealing magnetization treatment, the annealing temperature of the second annealing magnetization treatment is 250° C. to 260° C., and the magnetic field of the second annealing magnetization treatment is 300 Gs to 400 Gs; The angle between the magnetic field direction applied by the first annealing magnetization treatment and the magnetic field direction applied by the second annealing magnetization treatment is 70° to 110°, and both are parallel to the surfaces opposite to each other of the first pinned layer and the second pinned layer; The first pinning layer and the pinned layer form a first pinning field, and the second pinning layer and the free layer form a second pinning field. The directions of the first pinning field and the second pinning field are both parallel to the opposite surfaces of the first pinning layer and the second pinning layer, and the angle between the direction of the first pinning field and the direction of the second pinning field is 70° to 110°.

2. The tunnel magnetoresistance according to claim 1, wherein The Neel temperature of the material of the first pinned layer is greater than the Neel temperature of the material of the second pinned layer.

3. The tunnel magnetoresistance according to claim 1 or 2, characterized in that The thickness of the first pinning layer is 15 nm to 20 nm.

4. The tunnel magnetoresistance according to claim 1 or 2, characterized in that The thickness of the second pinning layer is 7 nm to 9 nm.

5. The tunnel magnetoresistance according to claim 1, wherein The thickness of the first free sub-layer is 2 nm to 2.2 nm; the material of the second free sub-layer includes NiFe or CoFe.

6. The tunnel magnetoresistance according to claim 1, wherein The pinned layer includes a first ferromagnetic layer, a non-ferromagnetic layer, and a second ferromagnetic layer that are stacked, and the first ferromagnetic layer is located between the first pinned layer and the non-ferromagnetic layer.

7. The tunnel magnetoresistance according to claim 6, characterized in that The material of the first ferromagnetic layer includes CoFe, and the thickness of the first ferromagnetic layer is 1.6nm~2.4nm; the material of the non-ferromagnetic layer includes Ru, and the thickness of the non-ferromagnetic layer is 0.7nm~0.9nm or 1.8nm~2nm; the material of the second ferromagnetic layer includes CoFeB, and the thickness of the second ferromagnetic layer is 2.4nm~2.8nm.

8. The tunnel magnetoresistance according to claim 7, characterized in that The thickness of the first ferromagnetic layer is 2 nm; the thickness of the non-ferromagnetic layer is 0.8 nm or 1.9 nm; and the thickness of the second ferromagnetic layer is 2.6 nm.

9. The tunnel magnetoresistance according to claim 1, wherein Also includes: A stabilizing layer of ferromagnetic material is located on a side of the second pinned layer facing away from the free layer, and the stabilizing layer is adapted to increase the stability of the second pinning field.

10. The tunnel magnetoresistance according to claim 9, characterized in that The material of the stabilization layer includes NiFe or CoFe, and the thickness of the stabilization layer is 4 nm to 6 nm.

11. A method for preparing a tunnel magnetoresistance, for forming the tunnel magnetoresistance according to any one of claims 1 to 10, characterized in that: The steps include: forming a first pinning layer, wherein the material of the first pinning layer includes an antiferromagnetic PtMn alloy, and the Neel temperature of PtMn is 330° C.; forming a pinned layer on one side of the first pinning layer; forming a tunnel barrier layer on a side of the pinned layer facing away from the first pinning layer; A free layer is formed on a side of the tunneling barrier layer facing away from the pinned layer, wherein the method for forming the free layer comprises: forming a first free sublayer on a side of the tunneling barrier layer facing away from the first pinned layer; and forming a second free sublayer on a side of the first free sublayer facing away from the tunneling barrier layer. The method for forming the free layer further comprises: forming a spacer layer between the steps of forming the first free sublayer and forming the second free sublayer; the material of the first free sublayer comprises CoFeB, the thickness of the second free sublayer is 4 nm to 7 nm, the material of the spacer layer comprises Ta, and the thickness of the spacer layer is 0.15 nm to 0.2 nm; forming a second pinning layer on a side of the free layer facing away from the tunneling barrier layer, wherein the material of the second pinning layer comprises an antiferromagnetic IrMn alloy, and the Neel temperature of IrMn is 270° C.; Performing a first annealing and magnetization treatment on the first pinned layer, wherein the annealing temperature of the first annealing and magnetization treatment is 330° C. to 350° C., and the magnetic field size of the first annealing and magnetization treatment is 8000 Gs to 12000 Gs; After the first annealing and magnetization treatment, performing a second annealing and magnetization treatment on the second pinned layer, wherein the annealing temperature of the second annealing and magnetization treatment is 250° C. to 260° C., and the magnetic field magnitude of the second annealing and magnetization treatment is 300 Gs to 400 Gs; The angle between the magnetic field direction applied by the first annealing magnetization treatment and the magnetic field direction applied by the second annealing magnetization treatment is 70° to 110°, and both are parallel to the surfaces opposite to each other of the first pinned layer and the second pinned layer; The first pinning layer and the pinned layer form a first pinning field, and the second pinning layer and the free layer form a second pinning field. The directions of the first pinning field and the second pinning field are both parallel to the opposite surfaces of the first pinning layer and the second pinning layer, and the angle between the direction of the first pinning field and the direction of the second pinning field is 70° to 110°.

12. The method for preparing a tunnel magnetoresistance according to claim 11, wherein: The Neel temperature of the material of the first pinned layer is greater than the Neel temperature of the material of the second pinned layer; The annealing temperature of the first annealing and magnetizing treatment is not lower than the Neel temperature of the material of the first pinned layer; and the annealing temperature of the second annealing and magnetizing treatment is lower than the Neel temperature of the material of the first pinned layer.

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