A magnetoresistive sensor and a method for manufacturing the same

Abstract

The present invention relates to the field of magnetic field measurement technology, and discloses a magnetoresistive sensor and a manufacturing method thereof. The magnetoresistive sensor includes a layer stack, and the layer stack includes a magnetic reference layer with a reference magnetization, a magnetic free layer with a magnetic free magnetization, a tunneling layer, and side electrodes arranged on both sides of the magnetic free layer. Among them, the reference magnetization is fixed and has a first magnetic orientation perpendicular to the sensor plane; the magnetic free magnetization can change in the presence of an external magnetic field perpendicular to the sensor plane; the side electrode is used to apply a first current parallel to the sensor plane to the magnetic free layer, so that the layer stack can be sensitive to the magnetic field perpendicular to the sensor plane. Through the synergistic effect of the magnetic free layer, the tunneling layer, the magnetic reference layer and the side electrodes in the layer stack, the magnetoresistive sensor can be sensitive to the magnetic field perpendicular to the sensor plane, and achieve high-sensitivity measurement of the Z-axis magnetic field.

Description

Technical Field

[0001] The present invention relates to the field of magnetic field measurement, and in particular to a magnetoresistive sensor and a manufacturing method thereof. Background Art

[0002] The magnetic field itself is a vector field, and magnetic sensors typically involve the measurement of the Z-axis magnetic field perpendicular to the sensor plane.

[0003] The measurement of the Z-axis magnetic field is mainly achieved through detection coils, Hall elements or magnetoresistive elements. The detection coil has low spatial resolution, limited sensitivity and limited frequency characteristics; the Hall element has low sensitivity, high power consumption and poor temperature characteristics.

[0004] Tunneling magnetoresistive sensors are used in magnetic field measurement and have the advantages of large resistance change rate, large output signal amplitude, high resistivity, low power consumption and high temperature stability. However, the sensitive direction of existing tunneling magnetoresistive sensors is generally in the plane direction, which limits their application in vertical magnetic field, three-axis vector magnetic field detection and other occasions.

[0005] The above contents are only used to assist in understanding the technical solution of the present invention and do not constitute an admission that the above contents are prior art. Summary of the invention

[0006] The main purpose of the present invention is to provide a magnetoresistive sensor sensitive to the Z-axis magnetic field and a manufacturing method thereof, aiming to improve the problem of low sensitivity of the sensor for measuring the Z-axis magnetic field.

[0007] To achieve the above object, a first aspect of the present invention provides a magnetoresistive sensor, wherein the magnetoresistive sensor comprises a layer stack; the layer stack comprises:

[0008] a magnetic reference layer having a reference magnetization that is fixed and has a first magnetic orientation perpendicular to the sensor plane;

[0009] a magnetically free layer having a magnetically free magnetization that can be changed in the presence of an external magnetic field perpendicular to the sensor plane;

[0010] a tunneling layer, the tunneling layer being arranged between the magnetic reference layer and the magnetic free layer;

[0011] Side electrodes are arranged on both sides of the magnetic free layer and are used to apply a first current parallel to the sensor plane to the magnetic free layer so that the layer stack can be sensitive to a magnetic field perpendicular to the sensor plane;

[0012] When the side electrode applies the first current to the magnetic free layer, the magnetic free layer has a second magnetic orientation and a third magnetic orientation perpendicular to the sensor plane in a ground state; the second magnetic orientation and the third magnetic orientation are antiparallel to each other.

[0013] According to some embodiments of the present invention, when the side electrode applies the first current to the magnetic free layer, the magnetoresistive sensor can linearly respond to an external magnetic field perpendicular to the sensor plane within a first preset magnetic field range.

[0014] According to some embodiments of the present invention, the current density of the first current is related to the coercive field of the magnetic free layer under an external magnetic field perpendicular to the sensor plane.

[0015] According to some embodiments of the present invention, the current density of the first current is 6-10 MA / cm2.

[0016] According to some embodiments of the present invention, the magnetic reference layer and the magnetic free layer have perpendicular anisotropy.

[0017] According to some embodiments of the present invention, the layer stack further comprises a substrate, a first metal multilayer film and a second metal multilayer film; the first metal multilayer film is arranged between the substrate and the magnetic free layer to induce perpendicular anisotropy of the magnetic free layer; the second metal multilayer film is arranged above the magnetic reference layer to induce perpendicular anisotropy of the magnetic reference layer;

[0018] According to some embodiments of the present invention, the first metal multilayer film and the second metal multilayer film are both obtained by alternating a plurality of first metal multilayers and second metal multilayers; the material of the first metal multilayer is cobalt or iron; the material of the second metal multilayer is one of platinum, palladium, gold, nickel or copper.

[0019] According to some embodiments of the present invention, the coercive field of the magnetic free layer under an external magnetic field perpendicular to the sensor plane is 10-100 Oe;

[0020] According to some embodiments of the present invention, the coercive field is related to the thickness of the first metal multilayer and the second metal multilayer in the first metal multilayer film.

[0021] According to some embodiments of the present invention, the layer stack further includes a natural antiferromagnetic layer, which is arranged on the second metal multilayer film to provide an exchange bias field for the magnetic reference layer.

[0022] According to some embodiments of the present invention, the magnetic reference layer has a fixed reference magnetization in a saturation magnetic field range to an external magnetic field perpendicular to the sensor plane; the saturation magnetic field range is related to the thickness of the natural antiferromagnetic layer.

[0023] According to some embodiments of the present invention, the saturation magnetic field range includes at least -100 Oe to +100 Oe.

[0024] According to some embodiments of the present invention, the layer stack also includes a first non-magnetic layer and a second non-magnetic layer; the first non-magnetic layer is arranged between the magnetic free layer and the first metal multilayer film; the second non-magnetic layer is arranged between the magnetic reference layer and the second metal multilayer film.

[0025] According to some embodiments of the present invention, the first metal multilayer film is obtained by alternating n first metal multilayers and n second metal multilayers, where n is an integer between 3 and 10.

[0026] According to some embodiments of the present invention, the second metal multilayer film is obtained by alternatingly arranging m first metal multilayers and m second metal multilayers, where m is an integer between 3 and 10.

[0027] According to some embodiments of the present invention, the side electrode includes a first side electrode layer and a second side electrode layer; the first side electrode layer is arranged on the left side of the magnetic free layer, and the second side electrode layer is arranged on the right side of the magnetic free layer.

[0028] According to some embodiments of the present invention, the magnetoresistive sensor also includes a top electrode layer for matching with the first side electrode layer or the second side electrode layer and outputting a response signal of the layer stack to a magnetic field perpendicular to the sensor plane; the top electrode layer is arranged on a side of the magnetic reference layer away from the tunneling layer.

[0029] To achieve the above objective, a second aspect of the present invention provides a method for manufacturing a magnetoresistive sensor, wherein the magnetoresistive sensor is the magnetoresistive sensor described above, and the magnetoresistive sensor includes a layer stack.

[0030] The method for manufacturing the layer stack comprises:

[0031] forming a multilayer film, the multilayer film comprising at least a magnetic reference layer, a tunneling layer, a magnetic free layer, a first side electrode layer and a second side electrode layer, wherein the tunneling layer is arranged between the reference layer and the magnetic free layer, and the first side electrode layer and the second side electrode layer are arranged on both sides of the magnetic free layer respectively;

[0032] The multilayer film is subjected to high temperature magnetic field annealing to obtain the layer stack.

[0033] In summary, the layer stack in the magnetoresistive sensor disclosed in the present invention includes a magnetic reference layer with a reference magnetization, a magnetic free layer with a magnetic free magnetization, a tunneling layer arranged between the magnetic reference layer and the magnetic free layer, and side electrodes arranged on both sides of the magnetic free layer. Among them, the reference magnetization is fixed and has a first magnetic orientation perpendicular to the sensor plane; the magnetic free magnetization can change in the presence of an external magnetic field perpendicular to the sensor plane; the side electrode is used to apply a first current parallel to the sensor plane to the magnetic free layer, so that the layer stack can be sensitive to the magnetic field perpendicular to the sensor plane. Through the synergistic effect of the magnetic free layer, the tunneling layer, the magnetic reference layer and the side electrodes in the layer stack, the magnetoresistive sensor can be sensitive to the magnetic field perpendicular to the sensor plane, and achieve high-sensitivity measurement of the Z-axis magnetic field. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 Schematic diagram of the ground state magnetic orientation of the layer stack in the magnetoresistive sensor according to an embodiment of the present invention;

[0035] Figure 2 This is a schematic diagram of the structure of the middle layer stack of the magnetoresistive sensor according to an embodiment of the present invention;

[0036] Figure 3 is a hysteresis loop diagram of the magnetic free layer in an embodiment of the present invention when the first current is not applied;

[0037] Figure 4 is a hysteresis loop diagram of the magnetic reference layer in an embodiment of the present invention;

[0038] Figure 5 A schematic diagram of the structure of a magnetoresistive sensor in an embodiment of the present invention;

[0039] Figure 6 hysteresis loop diagram of the magnetic free layer in the embodiment of the present invention when a current of 1 mA and 19 mA is applied respectively;

[0040] Figure 7 is a coercive field variation curve of the magnetic free layer when different currents are applied in an embodiment of the present invention;

[0041] Figure 8 Schematic diagram of the change in magnetic orientation of the middle layer stack of the magnetoresistive sensor under the Z-axis magnetic field according to an embodiment of the present invention.

[0042] The realization of the purpose, functional features and advantages of the present invention will be further explained in conjunction with embodiments and with reference to the accompanying drawings. DETAILED DESCRIPTION

[0043] It should be understood that the specific embodiments described herein are only used to explain the present invention, and are not used to limit the present invention.

[0044] The magnetic field itself is a vector field, and magnetic sensors typically involve the measurement of the Z-axis magnetic field perpendicular to the sensor plane.

[0045] The existing Z-axis magnetic field measurement is mainly achieved through detection coils, Hall elements or magnetoresistive elements. The detection coil has low spatial resolution, limited sensitivity and limited frequency characteristics; the Hall element has low sensitivity, high power consumption and poor temperature characteristics.

[0046] Tunneling magnetoresistive sensors are used in magnetic field measurement and have the advantages of large resistance change rate, large output signal amplitude, high resistivity, low power consumption and high temperature stability. However, the sensitive direction of existing tunneling magnetoresistive sensors is generally in the plane direction, which limits their application in vertical magnetic field, three-axis vector magnetic field detection and other occasions.

[0047] Therefore, an object of an embodiment of the present invention is to provide a magnetoresistive sensor and a method for manufacturing the same, in order to improve the problem of low sensitivity of existing sensors for measuring magnetic field on the Z axis.

[0048] The magnetoresistive sensor of this embodiment is sensitive to the Z-axis magnetic field perpendicular to the sensor plane. The easy axis direction of the magnetoresistive sensor is perpendicular to the sensor plane, that is, along the Z-axis direction; wherein the sensor plane is called the XY plane.

[0049] The magnetoresistive sensor of this embodiment includes a layer stack, which includes a magnetic reference layer, a tunneling layer, and a magnetic free layer stacked in sequence or inversely; wherein the stacking direction of each layer is the Z-axis direction.

[0050] The magnetic reference layer of this embodiment is a ferromagnetic material with perpendicular magnetic anisotropy. When applied to a magnetoresistive sensor, the magnetic reference layer has a fixed reference magnetization, which has a first magnetic orientation perpendicular to the magnetic reference layer, i.e., the sensor plane. The first magnetic orientation can be upward along the Z axis or downward along the Z axis. The interface of the magnetic reference layer can be square or circular, which is not limited here.

[0051] The magnetic free layer of this embodiment is a ferromagnetic material and also has magnetic perpendicular anisotropy; when applied to a magnetoresistive sensor, the magnetic free layer has a magnetic free magnetization, which can change in the case of an external magnetic field perpendicular to the magnetic free layer, i.e., the sensor plane, i.e., it is sensitive to the Z-axis magnetic field perpendicular to the sensor plane. The interface of the magnetic free layer can be square or circular, which is not limited here.

[0052] The layer stack of the present embodiment further includes side electrodes, which include a first side electrode layer and a second side electrode layer, and the first side electrode layer and the second side electrode layer are respectively arranged on both sides of the magnetic free layer; when applied to the magnetoresistive sensor, the side electrodes are used to apply a first current parallel to the sensor plane to the magnetic free layer, so that the magnetic free layer has a second magnetic orientation and a third magnetic orientation perpendicular to the sensor plane in the ground state, that is, when there is no external magnetic field, some magnetic domains of the magnetic free layer have the second magnetic orientation, and some magnetic domains have the third magnetic orientation that is antiparallel to each other. Wherein, "ground state" refers to the state without an external magnetic field.

[0053] Figure 1 FIG. 1 is a schematic diagram of the ground state magnetic orientation of the layer stack in the magnetoresistive sensor according to an embodiment of the present invention. Figure 1 As shown, the magnetic reference layer located above the tunneling layer has a reference magnetization, and its ground state magnetic orientation is fixed to be upward along the Z axis; the ground state magnetic orientation of the magnetic free layer located below the tunneling layer includes two types, the ground state magnetic orientation of half of the magnetic domains is upward along the Z axis, and the ground state magnetic orientation of the other half of the magnetic domains is downward along the Z axis.

[0054] The following combination Figure 2 , the structure of the layer stack in the magnetoresistive sensor according to an embodiment of the present invention is described.

[0055] like Figure 2 As shown, in the layer stack of the embodiment of the present invention, the magnetic free layer 301 is located above the substrate 100; the magnetic free layer 301 and the magnetic reference layer 501 are respectively located above and below the tunneling layer 400; and the first side electrode layer 601 and the second side electrode layer 602 in the side electrode are respectively arranged on both sides of the magnetic free layer 301.

[0056] The magnetic reference layer 501 of the embodiment of the present invention also includes a second metal multilayer film above it. The second metal multilayer film is used to induce perpendicular anisotropy of the magnetic reference layer 501. The second metal multilayer film is obtained by alternating a plurality of first metal multilayers 503 and second metal multilayers 504.

[0057] It should be noted that the material of the first metal multilayer 503 can be cobalt or iron, and the material of the second metal multilayer 504 can be platinum, palladium, gold, nickel or copper. The materials of the first metal multilayer and the second metal multilayer are not specifically limited here.

[0058] Specifically, the second metal multilayer film is obtained by alternately arranging m first metal multilayers 503 and m second metal multilayers 504, wherein m is a positive integer and m is preferably any integer between 3 and 10.

[0059] The second metal multilayer film of the embodiment of the present invention also includes a natural antiferromagnetic layer 505 above, which is used to provide an exchange bias field for the magnetic reference layer 501, so that the magnetic reference layer 501 has a fixed magnetic orientation parallel to the Z axis within a certain magnetic field range (i.e., the saturation magnetic field range).

[0060] It should be noted that the saturation magnetic field range is related to the thickness of the natural antiferromagnetic layer 505. The saturation magnetic field range at least includes -100Oe to 100Oe. The saturation magnetic field range is not specifically limited here.

[0061] In some embodiments, the magnetic reference layer 501 has a fixed reference magnetization to an external magnetic field perpendicular to the sensor plane within a range of ±100 Oe.

[0062] The embodiment of the present invention further includes a second non-magnetic layer 502 between the magnetic reference layer 501 and the second metal multilayer film. The material of the second non-magnetic layer 502 may be Ru or Ta.

[0063] The natural antiferromagnetic layer 505 of the embodiment of the present invention further includes a top electrode layer 701, which is used to lead out electrical signals. Further, the top electrode layer 701 is used to match the first side electrode layer 601 or the second side electrode layer 602, and output the response signal of the layer stack to the magnetic field perpendicular to the sensor plane. The top electrode layer 701 is arranged on the side of the magnetic reference layer 501 away from the tunneling layer 400.

[0064] The material of the tunneling layer 400 in the embodiment of the present invention may be MgO.

[0065] The magnetic free layer 301 of the embodiment of the present invention includes a first metal multilayer film below, and the first metal multilayer film is used to induce perpendicular anisotropy of the magnetic free layer 301. The first metal multilayer film is obtained by alternately arranging a plurality of first metal multilayers 303 and second metal multilayers 304. The material of the first metal multilayer 303 can be cobalt or iron; the material of the second metal multilayer 304 can be one of platinum, palladium, gold, nickel or copper.

[0066] The first metal multilayer film of the embodiment of the present invention is obtained by alternately arranging n first metal multilayers 303 and n second metal multilayers 304, where n is a positive integer and preferably any integer between 3-10.

[0067] The embodiment of the present invention further includes a first non-magnetic layer 302 between the magnetic free layer 301 and the first metal multilayer film. The second non-magnetic layer 302 may be Ru or Ta.

[0068] The first metal multilayer film of the embodiment of the present invention further includes a seed layer 200 below the first metal multilayer film, and the seed layer is located between the substrate 100 and the first metal multilayer film. The seed layer can be Ru or Ta.

[0069] The side electrode of the embodiment of the present invention applies a current parallel to the sensor plane to both sides of the magnetic free layer 301, the first non-magnetic layer 302, the first metal multilayer film and the seed layer 200 through the first side electrode layer 601 and the second side electrode layer 602. When the current is the first current, the coercive field of the magnetic free layer under the external magnetic field can be reduced from the first coercive field to zero, thereby enabling the magnetoresistive sensor with the layer stack to linearly respond to the Z-axis magnetic field perpendicular to the sensor plane within the first preset magnetic field range. Therefore, the magnitude of the first current is related to the first coercive field of the magnetic free layer.

[0070] It should be noted that in the embodiment of the present invention, no bottom electrode layer is provided below the magnetic free layer 301, and the electrical signal is drawn out through the first side electrode layer or the second side electrode layer on the side of the magnetic free layer. In other embodiments, a bottom electrode layer may also be provided separately below the magnetic free layer, which is not specifically limited here.

[0071] In some embodiments, the current density of the first current can be 6-10 MA / cm2.

[0072] In some embodiments, when the side electrode does not apply the first current to the magnetic free layer, the coercive field of the magnetic free layer under the external magnetic field perpendicular to the sensor plane, i.e., the first coercive field, is 10-100 Oe. The value of the first coercive field is generally related to the thickness of the magnetic free layer 301 and the thickness of the first metal multilayer 303 and the second metal multilayer 304 in the first metal multilayer film below the magnetic free layer 301.

[0073] It should be noted that the thickness of the magnetic free layer is generally higher than the superparamagnetic thickness. Definition of superparamagnetic thickness: When the ferromagnetic material is less than the superparamagnetic thickness, it will show superparamagnetic properties due to thermal disturbance. When there is no external magnetic field, the total magnetic moment is zero. When there is an external magnetic field, its magnetic moment will change with the external magnetic field. The magnetization intensity will have a large linear region near the zero magnetic field and finally reach saturation. If the thickness of the magnetic free layer is lower than the superparamagnetic thickness, the magnetoresistive sensor does not need to set up side electrodes to apply current to the magnetic free layer, and can achieve sensitivity to the Z-axis magnetic field.

[0074] The hysteresis loop diagram of the magnetic free layer in the embodiment of the present invention when no current is applied is as follows: Figure 3 As shown. Figure 3 The magnetic free layer has perpendicular magnetic anisotropy, and its first coercive field is about 35 Oe.

[0075] The hysteresis loop diagram of the magnetic reference layer in the embodiment of the present invention is as follows: Figure 4 As shown. Figure 4 , the magnetic reference layer has perpendicular magnetic anisotropy with a switching saturation field higher than 100 Oe.

[0076] The structural schematic diagram of the magnetoresistive sensor in the embodiment of the present invention is as follows Figure 5 As shown. Figure 5 The layer stack extends in the Z-axis direction, and an external power source applies a first current of Ix to the magnetic free layer through the first side electrode layer and the second side electrode layer on both sides of the magnetic free layer; the magnetoresistive sensor draws out an electrical signal through the first side electrode layer and the top electrode layer in the side electrode to obtain magnetoresistive RTMR information related to the external magnetic field.

[0077] The hysteresis loop diagram of the magnetic free layer under different currents in the embodiment of the present invention is shown in FIG. Figure 6 As shown. Figure 6 When the current applied by the side electrode to the magnetic free layer is 1mA (dashed line), the coercive field of the magnetic free layer is 34Oe; when the current applied by the side electrode to the magnetic free layer is 19mA, that is, the current density is 6.3 MA / cm2 (solid line), the coercive field of the magnetic free layer is only 0.5 Oe. This shows that the current applied by the side electrode to the magnetic free layer can reduce the coercive field of the magnetic free layer under the Z-axis external magnetic field within a certain range.

[0078] Figure 7 : is the coercive field variation curve of the magnetic free layer when different currents are applied in the embodiment of the present invention. Figure 7 As shown in FIG. 1 , the coercive field decreases as the current applied by the side electrode increases. Therefore, the coercive field can be close to 0 Oe, thereby enabling the output of the magnetic free layer to respond linearly to the Z-axis magnetic field.

[0079] In one embodiment of the present invention, when the current applied to the magnetic free layer is a first current, the first coercive field of the magnetic free layer is close to 0; when the layer stack having the magnetic free layer is applied to a magnetoresistive sensor, it can achieve a linear response under the action of a Z-axis magnetic field within a range of ±10 Oe.

[0080] Figure 8 Schematic diagram of the change of magnetic orientation of the middle layer stack of the magnetoresistive sensor in the Z-axis magnetic field according to the embodiment of the present invention. Figure 8When the Z-axis magnetic field is 10Oe, 5Oe, 0Oe, -5Oe, and -10Oe respectively, the magnetic orientation of the magnetic reference layer remains upward. When the Z-axis magnetic field is 0 Oe, the magnetic orientation of half of the magnetic domains in the magnetic free layer is arranged upward, and the magnetic orientation of half of the magnetic domains is arranged downward. At this time, the resistance of the magnetoresistive sensor is R1; when the Z-axis magnetic field increases from 0 Oe to 5 Oe, the magnetic orientation of some magnetic domains in the magnetic free layer is flipped from downward arrangement to upward arrangement. At this time, the resistance of the magnetoresistive sensor decreases from R1 to R2; when the Z-axis magnetic field increases from 5 Oe to 10 Oe, all the magnetic domains in the magnetic free layer are arranged upward, and at this time, the resistance of the magnetoresistive sensor is R3; when the Z-axis magnetic field decreases from 0 Oe to -5 Oe, the magnetic orientation of some magnetic domains in the magnetic free layer is flipped from upward arrangement to downward arrangement, and the resistance of the magnetoresistive sensor increases from R1 to R4; when the Z-axis magnetic field decreases from -5 Oe to -10 Oe, all the magnetic domains in the magnetic free layer are arranged downward, and at this time, the resistance of the magnetoresistive sensor increases from R4 to R5.

[0081] In summary, the magnetoresistive sensor provided by the embodiment of the present invention, through the synergistic effect of the magnetic free layer, tunnel layer, magnetic reference layer and side electrodes in the layer stack, adds side electrodes on both sides of the magnetic free layer, applies a first current parallel to the sensor plane to the magnetic free layer, changes the magnetic orientation of each magnetic domain in the magnetic free layer, and makes the coercive field of the magnetic free layer close to 0Oe, thereby achieving the technical effect of the magnetoresistive sensor being sensitive to the Z-axis magnetic field perpendicular to the sensor plane.

[0082] In order to apply the above technical effects, the magnetoresistive sensor of the embodiment of the present invention includes a sensor circuit in addition to the layer stack. The sensor circuit includes a sensor element, which is configured to detect a directional component of an external magnetic field on the layer stack that is perpendicular to the sensor plane to generate a voltage corresponding to the directional component.

[0083] In order to achieve the technical effect of the present invention, an embodiment of the present invention further provides a method for manufacturing a magnetoresistive sensor, and the magnetoresistive sensor is the magnetoresistive sensor mentioned above.

[0084] Specifically, the method for manufacturing the layer stack in the magnetoresistive sensor comprises:

[0085] Step S100: forming a multilayer film, the multilayer film at least comprising a reference layer, a tunneling layer, a magnetic free layer, a first side electrode layer and a second side electrode layer, wherein the tunneling layer is arranged between the reference layer and the magnetic free layer, and the first side electrode layer and the second side electrode layer are arranged on both sides of the magnetic free layer respectively;

[0086] In this step, in order to facilitate the formation of the first side electrode layer and the second side electrode layer, the magnetic free layer is arranged on the side close to the substrate, and the magnetic reference layer is arranged on the side away from the substrate.

[0087] Step S200: annealing the multilayer film in a high temperature magnetic field to obtain a layer stack.

[0088] In this step, the multilayer film is annealed in a high temperature environment, and a Z-axis magnetic field perpendicular to the sensor plane of the multilayer film is applied to the multilayer film, so that after annealing, the magnetic reference layer and the magnetic free layer in the layer stack have a magnetic field orientation along the Z axis.

[0089] It should be understood that the above is only an example and does not constitute any limitation on the technical solution of the present invention. In specific applications, technicians in this field can make settings as needed, and the present invention does not limit this.

Claims

1. A magnetoresistive sensor, characterized in that: Comprising a layer stack; the layer stack comprising: a magnetic reference layer having a reference magnetization that is fixed and has a first magnetic orientation perpendicular to the sensor plane; a magnetically free layer having a magnetically free magnetization that can be changed in the presence of an external magnetic field perpendicular to the sensor plane; a tunneling layer, the tunneling layer being arranged between the magnetic reference layer and the magnetic free layer; Side electrodes are arranged on both sides of the magnetic free layer and are used to apply a first current parallel to the sensor plane to the magnetic free layer so that the layer stack can be sensitive to a magnetic field perpendicular to the sensor plane; When the side electrode applies the first current to the magnetic free layer, the magnetic free layer has a second magnetic orientation and a third magnetic orientation perpendicular to the sensor plane in a ground state; the second magnetic orientation and the third magnetic orientation are antiparallel to each other; When the side electrode applies the first current to the magnetic free layer, the first current can make the coercive field of the magnetic free layer close to 0 Oe, and the magnetoresistive sensor can linearly respond to an external magnetic field perpendicular to the sensor plane within a first preset magnetic field range.

2. The magnetoresistive sensor according to claim 1, characterized in that: The current density of the first current is related to the coercive field of the magnetic free layer under an external magnetic field perpendicular to the sensor plane.

3. The magnetoresistive sensor according to claim 2, characterized in that: The current density of the first current is 6-10 MA / cm2.

4. The magnetoresistive sensor according to claim 1, characterized in that: The magnetic reference layer and the magnetic free layer have perpendicular anisotropy; The layer stack also includes a substrate, a first metal multilayer film, and a second metal multilayer film; The first metal multilayer film is arranged between the substrate and the magnetic free layer to induce perpendicular anisotropy of the magnetic free layer; The second metal multilayer film is arranged above the magnetic reference layer to induce perpendicular anisotropy of the magnetic reference layer; The first metal multilayer film and the second metal multilayer film are both obtained by alternating a plurality of first metal multilayers and second metal multilayers; the material of the first metal multilayer is cobalt or iron; the material of the second metal multilayer is one of platinum, palladium, gold, nickel or copper.

5. The magnetoresistive sensor according to claim 4, characterized in that: The coercive field of the magnetic free layer under an external magnetic field perpendicular to the sensor plane is 10-100 Oe; The coercive field is related to the thickness of the first metal multilayer and the second metal multilayer in the first metal multilayer film.

6. The magnetoresistive sensor according to claim 4, characterized in that: The layer stack further includes a natural antiferromagnetic layer, which is arranged on the second metal multilayer film and provides an exchange bias field for the magnetic reference layer; The magnetic reference layer has a fixed reference magnetization to an external magnetic field perpendicular to the sensor plane within a saturation magnetic field range; the saturation magnetic field range is related to the thickness of the natural antiferromagnetic layer.

7. The magnetoresistive sensor according to claim 6, characterized in that: The saturation magnetic field range includes at least -100Oe~+100Oe.

8. The magnetoresistive sensor according to claim 4, characterized in that: The layer stack further comprises a first non-magnetic layer and a second non-magnetic layer; The first non-magnetic layer is disposed between the magnetic free layer and the first metal multilayer film; the second non-magnetic layer is disposed between the magnetic reference layer and the second metal multilayer film; The first metal multilayer film is obtained by alternately arranging n first metal multilayers and n second metal multilayers, wherein n is an integer between 3 and 10; The second metal multilayer film is obtained by alternately arranging m first metal multilayers and m second metal multilayers, where m is an integer between 3 and 10.

9. The magnetoresistive sensor according to any one of claims 1 to 8, characterized in that: The side electrode includes a first side electrode layer and a second side electrode layer; the first side electrode layer is arranged on the left side of the magnetic free layer, and the second side electrode layer is arranged on the right side of the magnetic free layer; The magnetoresistive sensor further comprises a top electrode layer, which is used to match the first side electrode layer or the second side electrode layer and output a response signal of the layer stack to a magnetic field perpendicular to the sensor plane; The top electrode layer is arranged on a side of the magnetic reference layer away from the tunneling layer.

10. A method for manufacturing a magnetoresistive sensor, characterized in that: The magnetoresistive sensor is a magnetoresistive sensor according to any one of claims 1 to 9; The magnetoresistive sensor comprises a layer stack; The method for manufacturing the layer stack comprises: forming a multilayer film, the multilayer film comprising a magnetic reference layer, a tunneling layer, a magnetic free layer, a first side electrode layer and a second side electrode layer, wherein the tunneling layer is arranged between the reference layer and the magnetic free layer, and the first side electrode layer and the second side electrode layer are arranged on both sides of the magnetic free layer respectively; The multilayer film is subjected to high temperature magnetic field annealing to obtain the layer stack.

Images