Magnetic sensor, position detection device provided with the same, and manufacturing method of the magnetic sensor

Abstract

A magnetic sensor is provided in which the output value at the time when the strength of a signal magnetic field is 0 is shifted from 0 by the difference in the magnetization state of the magnetization fixing layer of each of a plurality of magnetoresistance effect layer stacks (110) of a first magnetoresistance effect element (MR1) and a fourth magnetoresistance effect element (MR4) and the magnetization state of the magnetization fixing layer of each of a plurality of magnetoresistance effect layer stacks (110) of a second magnetoresistance effect element (MR2) and a third magnetoresistance effect element (MR3).

Description

Technical Field

[0001] This invention relates to a magnetic sensor, a position detection device having the magnetic sensor, and a method for manufacturing the magnetic sensor. Background Technology

[0002] As a prior art document disclosing an actuator driver capable of correcting hand tremors, there is Japanese Patent Application Publication No. 2019-28340 (Patent Document 1). The actuator driver described in Patent Document 1 includes a Hall element, a magnet that applies a magnetic field to the Hall element, and a driver IC (Integrated Circuit) that receives a detection signal from the Hall element. The driver IC performs drive control based on the output change of the Hall element caused by the relative position change of the Hall element and the magnet.

[0003] Existing technical documents

[0004] Patent documents

[0005] Patent document 1: Japanese Patent Application Publication No. 2019-28340. Summary of the Invention

[0006] The problem that the invention aims to solve

[0007] Generally speaking, the output value of a Hall element is 0 when the strength of the applied magnetic field is 0. In terms of the performance of the driver IC, the Hall element and the magnet need to be configured so that the output value of the Hall element is 0 when the magnet is in a reference position relative to the Hall element. The degree of freedom in the magnetic circuit design related to the configuration relationship between the Hall element and other magnetic sensors and the magnet is low.

[0008] The present invention was made in view of the above-mentioned problems, and its object is to provide a magnetic sensor that can improve the degree of freedom of magnetic circuit design, a position detection device having the magnetic sensor, and a method for manufacturing the magnetic sensor.

[0009] Technical means for solving problems

[0010] The magnetic sensor according to the present invention comprises: a first magnetoresistive element; a second magnetoresistive element; a third magnetoresistive element; and a fourth magnetoresistive element. The first, second, third, and fourth magnetoresistive elements are electrically connected to each other to form a bridge circuit. When a signal magnetic field is applied, the second and third magnetoresistive elements exhibit a resistance change in the opposite direction to that of the first and fourth magnetoresistive elements. Each of the first, second, third, and fourth magnetoresistive elements comprises a plurality of magnetoresistive stacks electrically connected to each other. In each of the plurality of magnetoresistive stacks, a magnetization fixed layer, a non-magnetic layer, and a magnetization free layer whose magnetization direction changes according to the signal magnetic field are sequentially stacked. In all the magnetoresistive stacks of the plurality of magnetoresistive stacks of each of the first and fourth magnetoresistive elements, the magnetization fixed layer has a magnetization state fixed along a first direction. In a portion of the plurality of magnetoresistive effect layers of each of the second and third magnetoresistive effect elements, the magnetization fixing layer has a magnetization state fixed along a second direction opposite to the first direction. Furthermore, the remaining portions of the plurality of magnetoresistive effect layers include at least one of the following: a portion where the magnetization fixing layer has a magnetization state fixed along a direction different from the second direction; and a portion where the magnetization fixing layer has a magnetization state in which the magnetization direction changes according to the aforementioned signal magnetic field. In the magnetic sensor, the output value when the intensity of the aforementioned signal magnetic field is 0 shifts from 0 due to the difference between the magnetization state of the magnetization fixing layer of each of the plurality of magnetoresistive effect layers of the first and fourth magnetoresistive effect elements and the magnetization state of the magnetization fixing layer of each of the plurality of magnetoresistive effect layers of the second and third magnetoresistive effect elements.

[0011] The effects of the invention

[0012] According to the present invention, the degree of freedom in magnetic circuit design can be increased. Attached Figure Description

[0013] Figure 1 This is a circuit diagram illustrating the structure of a magnetic sensor according to an embodiment of the present invention.

[0014] Figure 2 This is a perspective view showing the structure of the magnetoresistive effect element of a magnetic sensor according to an embodiment of the present invention.

[0015] Figure 3 Viewed from the direction of arrow III Figure 2 A partial side view of the magnetoresistive effect element.

[0016] Figure 4 It is shown in magnification Figure 3A partial side view of part IV of the magnetoresistive element.

[0017] Figure 5 This is a circuit diagram showing the electrical connections of the magnetoresistive effect element included in a magnetic sensor according to an embodiment of the present invention.

[0018] Figure 6 This is a cross-sectional view showing the magnetization state of the magnetization fixing layer of each of the first magnetoresistive effect element, the second magnetoresistive effect element, the third magnetoresistive effect element, and the fourth magnetoresistive effect element in a magnetic sensor according to an embodiment of the present invention.

[0019] Figure 7 This is a partial side view showing the state in which a magnetic field is applied to the magnetoresistive laminate while heat treatment is being performed.

[0020] Figure 8 This is a partial side view showing the state where the magnetic field applied to the magnetoresistive laminate has stopped and the temperature has been reduced to room temperature.

[0021] Figure 9 This is a partial side view showing the state in which the magnetoresistive effect stack is patterned into a point shape.

[0022] Figure 10 It is a cross-sectional view showing a state in which a magnetic field toward the second direction is applied to all the magnetoresistive effect stacks of the first magnetoresistive effect element and the fourth magnetoresistive effect element, respectively, while heat treatment is being performed.

[0023] Figure 11 It is a cross-sectional view showing a state in which a magnetic field toward a first direction is applied to a portion of the plurality of magnetoresistive effect stacks of the second magnetoresistive effect element and the third magnetoresistive effect element while heat treatment is performed.

[0024] Figure 12 This is a cross-sectional view showing the magnetization state of the magnetization fixing layer of each of the multiple magnetoresistive effect layers of the first magnetoresistive effect element, the second magnetoresistive effect element, the third magnetoresistive effect element, and the fourth magnetoresistive effect element in the magnetic sensor involved in the comparative example.

[0025] Figure 13 This is a graph showing the relationship between the output and the rate of change of resistance in the magnetic sensor involved in this embodiment and comparative examples.

[0026] Figure 14 This is a front view showing the structure of a position detection device according to an embodiment of the present invention.

[0027] Figure 15 Viewed from the magnet side Figure 14The 3D image obtained by the position detection device shown.

[0028] Figure 16 This is a graph showing the relationship between the combined output of the first magnetic sensor and the second magnetic sensor and the rotation angle of the magnet in the position detection device according to this embodiment and comparative example. Detailed Implementation

[0029] Hereinafter, a magnetic sensor according to an embodiment of the present invention, a position detection device including the magnetic sensor, and a method for manufacturing the magnetic sensor will be described with reference to the accompanying drawings. In the following description of the embodiment, the same or equivalent parts in the drawings will be given the same reference numerals, and their descriptions will not be repeated.

[0030] Figure 1 This is a circuit diagram illustrating the structure of a magnetic sensor according to one embodiment of the present invention. Figure 1 As shown, a magnetic sensor 1 according to an embodiment of the present invention includes: a first magnetoresistive effect element 100 (MR1), a second magnetoresistive effect element 100 (MR2), a third magnetoresistive effect element 100 (MR3), and a fourth magnetoresistive effect element 100 (MR4).

[0031] The first magnetoresistive element 100 (MR1), the second magnetoresistive element 100 (MR2), the third magnetoresistive element 100 (MR3), and the fourth magnetoresistive element 100 (MR4) are interconnected in a full bridge configuration to form a bridge circuit.

[0032] Specifically, a first series circuit, formed by connecting the first magnetoresistive element 100 (MR1) and the second magnetoresistive element 100 (MR2) in series, is connected in parallel with a second series circuit, formed by connecting the third magnetoresistive element 100 (MR3) and the fourth magnetoresistive element 100 (MR4) in series. A driving voltage V can be applied to the bridge circuit. The midpoint V+ of the first series circuit and the midpoint V- of the second series circuit are electrically connected to the differential amplifier A.

[0033] like Figure 1 As shown, the detection axis direction D1 of the first magnetoresistive effect element 100 (MR1) and the detection axis direction D4 of the fourth magnetoresistive effect element 100 (MR4) are opposite to the detection axis direction D2 of the second magnetoresistive effect element 100 (MR2) and the detection axis direction D3 of the third magnetoresistive effect element 100 (MR3).

[0034] Therefore, when a signal magnetic field is applied, the second magnetoresistive element 100 (MR2) exhibits a resistance change in the opposite direction to that of the first magnetoresistive element 100 (MR1). Similarly, when a signal magnetic field is applied, the third magnetoresistive element 100 (MR3) exhibits a resistance change in the opposite direction to that of the fourth magnetoresistive element 100 (MR4).

[0035] Figure 2 This is a perspective view showing the structure of the magnetoresistive effect element of a magnetic sensor according to an embodiment of the present invention. Figure 3 Viewed from the direction of arrow III Figure 2 A partial side view of the magnetoresistive effect element. Figure 4 It is shown in magnification Figure 3 A partial side view of part IV of the magnetoresistive element.

[0036] like Figures 2 to 4 As shown, the magnetoresistive effect element 100 of the magnetic sensor according to one embodiment of the present invention includes an upper electrode 120, a lower electrode 130, and a magnetoresistive effect laminate 110 sandwiched between the upper electrode 120 and the lower electrode 130.

[0037] The upper electrodes 120 are arranged in a matrix, spaced apart from each other in the X-axis and Y-axis directions. In this embodiment, the upper electrodes 120 have a circular plate shape. The diameter of the upper electrodes 120 is, for example, 9 μm. The thickness of the upper electrodes 120 is, for example, 0.1 μm. The center-to-center distance P2 between adjacent upper electrodes 120 is, for example, 20 μm.

[0038] The lower electrodes 130 are arranged in a matrix, spaced apart from each other in the X-axis and Y-axis directions. In this embodiment, the lower electrodes 130 have a circular plate shape. The diameter of the lower electrodes 130 is, for example, 9 μm. The thickness of the lower electrodes 130 is, for example, 0.1 μm. The center-to-center distance P2 between adjacent lower electrodes 130 is, for example, 20 μm. The lower electrodes 130 are spaced apart from a portion of the upper electrodes 120 in the Z-axis direction.

[0039] A magnetoresistive laminate 110 is sandwiched between an upper electrode 120 and a lower electrode 130 that are opposite each other. The magnetoresistive laminate 110 has a cylindrical shape. The diameter of the magnetoresistive laminate 110 is, for example, 3 μm. The thickness of the magnetoresistive laminate 110 is, for example, 0.035 μm.

[0040] In this embodiment, a first magnetoresistive layer Ra and a second magnetoresistive layer Rb are disposed spaced apart from each other in the Y-axis direction between the upper electrode 120 and the lower electrode 130, respectively. The center-to-center spacing P1 between adjacent first magnetoresistive layer Ra and second magnetoresistive layer Rb is, for example, 10 μm. The center-to-center spacing between adjacent first magnetoresistive layer Ra and adjacent second magnetoresistive layer Rb in the X-axis direction is, for example, 10 μm.

[0041] In this embodiment, the magnetoresistive effect element 100 is a TMR (Tunnel Magneto Resistance) element. Alternatively, the magnetoresistive effect element 100 may also be a GMR (Giant Magnetoresistance) element. In the magnetoresistive effect stack 110, a magnetization fixed layer, a non-magnetic layer, and a magnetization free layer whose magnetization direction changes according to the signal magnetic field are stacked sequentially.

[0042] Specifically, such as Figure 4 As shown, a base layer 114, an antiferromagnetic layer 115, a pinning layer 116, a coupling layer 117, a reference layer 111, a non-magnetic layer 112, and a magnetized free layer 113 are sequentially stacked on the lower electrode 130. Here, the stacked iron fixing layer composed of the pinning layer 116, the coupling layer 117, and the reference layer 111 is a magnetized fixing layer.

[0043] The magnetized free layer 113 is a soft ferromagnetic layer whose magnetization direction changes according to an external magnetic field, such as a signal magnetic field. The magnetized free layer 113 is composed of a magnetic material whose main component is at least one element selected from Co, Fe, and Ni. For example, it can be composed of CoFe, NiFe, CoFeB, or Heusler alloys. The magnetized free layer 113 can be a single layer or a stack of ferromagnetic free layers.

[0044] The nonmagnetic layer 112 is, for example, a nonmagnetic tunneling barrier layer made of MgO, which is thin enough to allow tunneling current to pass through based on quantum mechanics. In addition to MgO, the nonmagnetic layer 112 may also be made of oxides or nitrides of Al, Ti, or Hf.

[0045] The reference layer 111 is antiferromagnetically coupled to the pinning layer 116 via the coupling layer 117. That is, the magnetization direction of the reference layer 111 is antiparallel to the magnetization direction of the pinning layer 116. The reference layer 111 is made of a ferromagnetic material such as CoFe, CoFeB, or Heulser alloy.

[0046] The coupling layer 117 is made of a nonmagnetic material such as Ru, Ir, Rh, or Cr that generates RKKY interactions. The pinning layer 116 is made of a ferromagnetic material such as CoFe or CoFeB. The antiferromagnetic layer 115 is made of an antiferromagnetic material containing Mn, such as an alloy containing any one of Ni, Fe, Pd, Pt, and Ir and Mn, an alloy containing Pd, Pt, and Mn, or an alloy containing Cr, Pt, and Mn. Specifically, the antiferromagnetic layer 115 is made of IrMn, PtMn, PdPtMn, or CrPtMn.

[0047] The substrate layer 114 is provided to allow the crystal of the antiferromagnetic layer 115 to grow properly. The substrate layer 114 is composed of, for example, Ta, W, Mo, Cr, Ti, Zr, Ni, Au, Ag, Cu, Pt, Ru, or Ni-Fe.

[0048] like Figure 2 As shown, multiple electrode rows, including upper electrodes 120 and lower electrodes 130 arranged in the X-axis direction, are interconnected by wiring in a meandering pattern. Specifically, the upper electrode 120 located at the end of the first electrode row is connected to a first wiring L1. The lower electrodes 130 located at the ends of the first and second electrode rows are interconnected by a second wiring L2. The upper electrodes 120 located at the ends of the second and third electrode rows are interconnected by a third wiring L3. The lower electrode 130 located at the end of the third electrode row is connected to a fourth wiring L4.

[0049] Furthermore, the structure of the magnetoresistive effect element 100 is not limited to the above; it can be any structure capable of detecting the magnetic field of the signal.

[0050] Figure 5 This is a circuit diagram illustrating the electrical connections of the magnetoresistive element included in a magnetic sensor according to an embodiment of the present invention. Figure 5 As shown, in the magnetoresistive effect element 100, multiple parallel connection portions formed by connecting the first magnetoresistive effect stack Ra and the second magnetoresistive effect stack Rb in parallel are connected in series. Furthermore, the electrical connection method in the magnetoresistive effect element 100 is not limited to... Figure 5 As shown, multiple magnetoresistive effect stacks 110 can be electrically connected to each other in series or in parallel.

[0051] Figure 6 This is a cross-sectional view showing the magnetization state of the magnetization fixing layer of each of the first magnetoresistive effect element, the second magnetoresistive effect element, the third magnetoresistive effect element, and the fourth magnetoresistive effect element in a magnetic sensor according to an embodiment of the present invention.

[0052] like Figure 6As shown, the number of multiple magnetoresistive effect stacks 110 of each of the first magnetoresistive effect element 100 (MR1), the second magnetoresistive effect element 100 (MR2), the third magnetoresistive effect element 100 (MR3), and the fourth magnetoresistive effect element 100 (MR4) is equal to that of each other.

[0053] Therefore, the maximum resistance values ​​that the plurality of magnetoresistive effect layers 110 of each of the first magnetoresistive effect element 100 (MR1), the second magnetoresistive effect element 100 (MR2), the third magnetoresistive effect element 100 (MR3), and the fourth magnetoresistive effect element 100 (MR4) can maintain are equal to each other. The maximum resistance value that the plurality of magnetoresistive effect layers 110 can maintain refers to the sum of the resistance values ​​shown by each of the plurality of magnetoresistive effect layers 110 when a signal magnetic field is applied, provided that all the magnetized fixed layers of the plurality of magnetoresistive effect layers 110 in the magnetoresistive effect element 100 have a magnetization state fixed in the same direction.

[0054] like Figure 6 As shown, in this embodiment, the plurality of magnetoresistive effect stacks 110 included in the first magnetoresistive effect element 100 (MR1), the second magnetoresistive effect element 100 (MR2), the third magnetoresistive effect element 100 (MR3), and the fourth magnetoresistive effect element 100 (MR4) are located in a double rotationally symmetric position when viewed from the stacking direction (Z-axis direction) of the plurality of magnetoresistive effect stacks 110.

[0055] Furthermore, the multiple magnetoresistive effect stacks 110 included in the first magnetoresistive effect element 100 (MR1), the second magnetoresistive effect element 100 (MR2), the third magnetoresistive effect element 100 (MR3), and the fourth magnetoresistive effect element 100 (MR4) can also be located in a fourfold rotationally symmetric position when viewed from the stacking direction (Z-axis direction) of the multiple magnetoresistive effect stacks 110.

[0056] In addition, the multiple magnetoresistive effect stacks 110 included in the first magnetoresistive effect element 100 (MR1), the second magnetoresistive effect element 100 (MR2), the third magnetoresistive effect element 100 (MR3), and the fourth magnetoresistive effect element 100 (MR4) do not necessarily need to be located in a rotationally symmetrical position.

[0057] like Figure 6As shown, in each of the first magnetoresistive effect element 100 (MR1) and the fourth magnetoresistive effect element 100 (MR4), the magnetization fixing layer has a magnetization state fixed along a first direction in all the magnetoresistive effect stacks 110. Specifically, the magnetization direction D11 of all the reference layers 111 of the multiple magnetoresistive effect stacks 110 in the first magnetoresistive effect element 100 (MR1) and the magnetization direction D14 of all the reference layers 111 of the multiple magnetoresistive effect stacks 110 in the fourth magnetoresistive effect element 100 (MR4) are fixed toward the first direction.

[0058] In a portion of the plurality of magnetoresistive effect layers 110 in each of the second magnetoresistive effect element 100 (MR2) and the third magnetoresistive effect element 100 (MR3), the magnetization fixing layer has a magnetization state fixed along a second direction opposite to the first direction. Specifically, the magnetization direction D12 of a portion of the reference layer 111 in the plurality of magnetoresistive effect layers 110 in the second magnetoresistive effect element 100 (MR2) and the magnetization direction D13 of a portion of the reference layer 111 in the plurality of magnetoresistive effect layers 110 in the third magnetoresistive effect element 100 (MR3) are fixed toward the second direction.

[0059] In this embodiment, in the remaining portions of the plurality of magnetoresistive effect stacks 110 of each of the second magnetoresistive effect element 100 (MR2) and the third magnetoresistive effect element 100 (MR3), the magnetization fixing layer has a magnetization state in which the magnetization direction changes according to the signal magnetic field. That is, the reference layer 111 of the remaining portions of the plurality of magnetoresistive effect stacks 110 of each of the second magnetoresistive effect element 100 (MR2) and the third magnetoresistive effect element 100 (MR3) does not have a fixed magnetization direction.

[0060] Furthermore, in the remaining portions of the plurality of magnetoresistive effect stacks 110 of each of the second magnetoresistive effect element 100 (MR2) and the third magnetoresistive effect element 100 (MR3), the magnetization fixing layer may also have a magnetization state fixed in a direction different from the second direction. That is, the reference layer 111 of the remaining portions of the plurality of magnetoresistive effect stacks 110 of each of the second magnetoresistive effect element 100 (MR2) and the third magnetoresistive effect element 100 (MR3) may also be fixed in a direction different from the second direction. This direction different from the second direction is, for example, the first direction.

[0061] In addition, the remaining portion of the plurality of magnetoresistive effect stacks 110 of each of the second magnetoresistive effect element 100 (MR2) and the third magnetoresistive effect element 100 (MR3) may also include the following two parts: a portion of the magnetization fixing layer having a magnetization state in which the magnetization direction changes according to the signal magnetic field, and a portion of the magnetization fixing layer having a magnetization state fixed in a direction different from the second direction.

[0062] According to the above structure, the first magnetoresistive effect element 100 (MR1), the second magnetoresistive effect element 100 (MR2), the third magnetoresistive effect element 100 (MR3), and the fourth magnetoresistive effect element 100 (MR4) each detect the magnetic field component in a direction orthogonal to the stacking direction (Z-axis direction) of the magnetoresistive effect stack 110.

[0063] The manufacturing method of the magnetic sensor according to this embodiment will be described below. Figures 1 to 5 As shown, a first magnetoresistive effect element 100 (MR1), a second magnetoresistive effect element 100 (MR2), a third magnetoresistive effect element 100 (MR3), and a fourth magnetoresistive effect element 100 (MR4) are formed. The first magnetoresistive effect element 100 (MR1), the second magnetoresistive effect element 100 (MR2), the third magnetoresistive effect element 100 (MR3), and the fourth magnetoresistive effect element 100 (MR4) are electrically connected to each other to form a bridge circuit, and each of them includes multiple magnetoresistive effect stacks 110. Each magnetoresistive effect stack 110 has a magnetized fixed layer, a non-magnetic layer 112, and a magnetized free layer 113 stacked sequentially.

[0064] Here, a method for making the magnetization fixation layer in the magnetoresistive effect stack 110 a magnetization state fixed in a certain direction will be described. Figure 7 This is a partial side view showing the state in which a magnetic field is applied to the magnetoresistive laminate while heat treatment is being performed.

[0065] like Figure 7 As shown, after the MR film is formed, a magnetic field B is applied in one direction while heating for a certain period of time. At this time, the magnetization direction D116 of the pinned layer 116, the magnetization direction D111 of the reference layer 111, and the magnetization direction D113 of the magnetized free layer 113 are all oriented in the same direction as the magnetic field B.

[0066] Figure 8 This is a partial side view showing the state after the magnetic field on the magnetoresistive laminate has been stopped and the temperature has been reduced to room temperature. (See attached image.) Figure 8 As shown, by stopping the applied magnetic field and cooling to room temperature, the magnetization direction D111 of the reference layer 111 becomes opposite, and the magnetization direction D116 of the pinned layer 116 is antiparallel to the magnetization direction D111 of the reference layer 111. The magnetization direction D113 of the magnetized free layer 113 is oriented in the same direction as the magnetization direction D111 of the reference layer 111.

[0067] Figure 9 This is a partial side view showing the state in which the magnetoresistive effect stack is patterned into point shapes. (e.g.) Figure 9As shown, by patterning the magnetoresistive effect stack 110 into a dot shape, the magnetization direction of the magnetized free layer 113 is isotropic and varies according to the signal magnetic field.

[0068] In the manufacturing method of the magnetic sensor according to this embodiment, the following steps are performed when fixing the magnetization direction of the magnetization fixing layer in the plurality of magnetoresistive effect stacks 110.

[0069] Figure 10 It is a cross-sectional view showing a state in which a magnetic field toward the second direction is applied to all the magnetoresistive effect stacks of the first magnetoresistive effect element and the fourth magnetoresistive effect element, respectively, while heat treatment is being performed.

[0070] like Figure 10 As shown, a magnetic field B1 oriented in the second direction is applied to all magnetoresistive stacks 110 of the plurality of magnetoresistive stacks 110 of each of the first magnetoresistive element 100 (MR1) and the fourth magnetoresistive element 100 (MR4) while heating for a certain period of time. That is, all magnetoresistive stacks 110 of the plurality of magnetoresistive stacks 110 of each of the first magnetoresistive element 100 (MR1) and the fourth magnetoresistive element 100 (MR4) are located within the heating region H, while all magnetoresistive stacks 110 of the plurality of magnetoresistive stacks 110 of each of the second magnetoresistive element 100 (MR2) and the third magnetoresistive element 100 (MR3) are not located within the heating region H.

[0071] Subsequently, by applying a magnetic field B1 while cooling to room temperature, in all the magnetoresistive effect stacks 110 of the plurality of magnetoresistive effect stacks 110 of the first magnetoresistive effect element 100 (MR1) and the fourth magnetoresistive effect element 100 (MR4), the magnetization fixation layer becomes a magnetized state fixed along the first direction.

[0072] Figure 11 It is a cross-sectional view showing a state in which a magnetic field toward a first direction is applied to a portion of the plurality of magnetoresistive effect stacks of the second magnetoresistive effect element and the third magnetoresistive effect element while heat treatment is performed.

[0073] like Figure 11As shown, while applying a magnetic field B2 toward a first direction to all magnetoresistive effect stacks 110 of each of the second magnetoresistive effect element 100 (MR2) and the third magnetoresistive effect element 100 (MR3), only a portion of the magnetoresistive effect stacks 110 of each of the second magnetoresistive effect element 100 (MR2) and the third magnetoresistive effect element 100 (MR3) is heated for a certain period of time. That is, a portion of the magnetoresistive effect stacks 110 of each of the second magnetoresistive effect element 100 (MR2) and the third magnetoresistive effect element 100 (MR3) is located within the heating region H, while the remaining portions of the magnetoresistive effect stacks 110 of each of the second magnetoresistive effect element 100 (MR2) and the third magnetoresistive effect element 100 (MR3) are not located within the heating region H.

[0074] Subsequently, by applying magnetic field B2 while cooling to room temperature, in only a portion of the multiple magnetoresistive effect stacks 110 of the second magnetoresistive effect element 100 (MR2) and the third magnetoresistive effect element 100 (MR3), the magnetization fixation layer becomes a magnetized state fixed along the second direction.

[0075] Through the above-described processes, it is possible to manufacture products with... Figure 6 The magnetic sensor is shown in a magnetized state. Furthermore, when the remaining portions of the plurality of magnetoresistive effect stacks 110 of each of the second magnetoresistive effect element 100 (MR2) and the third magnetoresistive effect element 100 (MR3) include portions of a magnetization fixing layer having a magnetization state fixed in a direction different from the second direction, at least a portion of the remaining portions of the plurality of magnetoresistive effect stacks 110 of each of the second magnetoresistive effect element 100 (MR2) and the third magnetoresistive effect element 100 (MR3) are heated for a certain period of time while a magnetic field in a direction different from the second direction is applied to them.

[0076] The heat treatment in this process can also be performed by the thermal effects of heating all of the multiple magnetoresistive effect stacks 110 of the first magnetoresistive effect element 100 (MR1) and the fourth magnetoresistive effect element 100 (MR4), or by the thermal effects of heating a portion of the multiple magnetoresistive effect stacks 110 of the second magnetoresistive effect element 100 (MR2) and the third magnetoresistive effect element 100 (MR3). That is, at least a portion of the remaining portion of the multiple magnetoresistive effect stacks 110 of the second magnetoresistive effect element 100 (MR2) and the third magnetoresistive effect element 100 (MR3) can be heat-treated by thermal effects while a magnetic field B1 or magnetic field B2 is applied in a direction different from the first direction and the second direction.

[0077] Here, the magnetic sensor involved in the comparative example will be described. Figure 12 This is a cross-sectional view showing the magnetization state of the magnetization fixing layer of each of the multiple magnetoresistive effect layers of the first magnetoresistive effect element, the second magnetoresistive effect element, the third magnetoresistive effect element, and the fourth magnetoresistive effect element in the magnetic sensor involved in the comparative example.

[0078] like Figure 12 As shown, in the magnetic sensor involved in the comparative example, in all the magnetoresistive effect stacks 110 of the plurality of magnetoresistive effect stacks 110 of each of the first magnetoresistive effect element 100 (MR1) and the fourth magnetoresistive effect element 100 (MR4), the magnetization fixing layer is in a magnetization state fixed along the first direction, and in all the magnetoresistive effect stacks 110 of the plurality of magnetoresistive effect stacks 110 of each of the second magnetoresistive effect element 100 (MR2) and the third magnetoresistive effect element 100 (MR3), the magnetization fixing layer is in a magnetization state fixed along the second direction.

[0079] Figure 13 This is a graph showing the relationship between the output and the rate of change of resistance in the magnetic sensor involved in this embodiment and comparative examples. Figure 13 In the diagram, the vertical axis represents the output of the magnetic sensor, and the horizontal axis represents the rate of change of resistance of the magnetoresistive element. A dashed line represents the approximate straight line Lr of the data from the magnetic sensor involved in the comparative example, while a dashed line represents the approximate straight line Le of the data from the magnetic sensor involved in this embodiment. The rate of change of resistance is 0 when the strength of the signal magnetic field is 0.

[0080] like Figure 13 As shown, the magnetic sensor in the comparative example has an output value of 0 when the strength of the signal magnetic field is 0. On the other hand, regarding the magnetic sensor 1 according to this embodiment, the output value of the magnetic sensor when the strength of the signal magnetic field is 0 shifts from 0. Furthermore, the slope of the line Le, which represents the detection sensitivity of the magnetic sensor 1 according to this embodiment, is approximately the same as the slope of the line Lr, which represents the detection sensitivity of the magnetic sensor according to the comparative example.

[0081] Thus, in the magnetic sensor 1 according to this embodiment, the output value when the strength of the signal magnetic field is 0 shifts from 0 due to the difference between the magnetization state of the magnetization fixing layer of the plurality of magnetoresistive effect stacks 110 of the first magnetoresistive effect element 100 (MR1) and the fourth magnetoresistive effect element 100 (MR4) and the magnetization state of the magnetization fixing layer of the plurality of magnetoresistive effect stacks 110 of the second magnetoresistive effect element 100 (MR2) and the third magnetoresistive effect element 100 (MR3).

[0082] The following describes a position detection device equipped with the magnetic sensor described in this embodiment.

[0083] Figure 14 This is a front view showing the structure of a position detection device according to an embodiment of the present invention. Figure 15 Viewed from the magnet side Figure 14 The image shown is a 3D view obtained by the position detection device. Figure 14 and Figure 15 The image shows the magnet in its reference position.

[0084] like Figure 14 and Figure 15 As shown, a position detection device 10 according to one embodiment of the present invention includes a first magnetic sensor 1A and a second magnetic sensor 1B, a magnet 20, and a coil 30. The magnet 20 and the coil 30 constitute a so-called voice coil motor. The position detection device 10 is electrically connected to a driver IC (not shown).

[0085] The magnet 20 is movable relative to each of the first magnetic sensor 1A and the second magnetic sensor 1B from a reference position. In this embodiment, the magnet 20 is supported so as to be rotatable about its central axis C, which extends along the Z-axis. Furthermore, the magnet 20 may also be supported so as to be movable along the Y-axis.

[0086] The first magnetic sensor 1A and the second magnetic sensor 1B each detect the signal magnetic field B20 applied from the magnet 20. Based on the detection values ​​of the first magnetic sensor 1A and the second magnetic sensor 1B, the rotation angle of the magnet 20 is detected.

[0087] like Figure 14 and Figure 15 As shown, the first magnetic sensor 1A and the second magnetic sensor 1B are each disposed at a position that is not opposite to the central part of the magnet 20 when it is in the reference position.

[0088] Figure 16 This is a graph showing the relationship between the combined output of the first magnetic sensor and the second magnetic sensor and the rotation angle of the magnet in the position detection device according to this embodiment and comparative example. Figure 16 In the diagram, the vertical axis shows the combined output of the first and second magnetic sensors, and the horizontal axis shows the rotation angle of the magnet 20 from the reference position. The data L0 of the position detection device involved in the comparative example is shown in solid line, and the data LA of the position detection device involved in this embodiment is shown in dashed line.

[0089] In the position detection device involved in the comparative example, only the magnetoresistive effect elements of the first and second magnetic sensors have Figure 12 The magnetization state shown is different from that of the first magnetic sensor 1A and the second magnetic sensor 1B.

[0090] like Figure 16 As shown, in the position detection device of the comparative example, the first magnetic sensor and the second magnetic sensor are each positioned at a position not opposite to the center of the magnet 20 when it is in the reference position. Therefore, when the rotation angle is 0, i.e., when the magnet 20 is in the reference position, the combined output value of the first and second magnetic sensors shifts significantly from 0. In this case, the control driver IC cannot be driven based on the detection signals of the first and second magnetic sensors.

[0091] On the other hand, in the position detection device 10 according to this embodiment, by shifting the output values ​​of the first magnetic sensor 1A and the second magnetic sensor 1B from 0 when the strength of the signal magnetic field is 0, the combined output value of the first magnetic sensor 1A and the second magnetic sensor 1B when the rotation angle is 0, i.e., when the magnet 20 is at the reference position, is shifted to be near 0. Therefore, the control driver IC can be driven based on the detection signals of the first magnetic sensor 1A and the second magnetic sensor 1B.

[0092] Thus, in the position detection device 10 according to this embodiment, by moving the output value of the magnetic sensor 1 when the signal magnetic field is 0 from 0, the degree of freedom in the magnetic circuit design related to the configuration relationship between the magnetic sensor 1 and the magnet 20 can be increased.

[0093] In the magnetic sensor described in this embodiment, the structure of the magnetoresistive effect element 100 can be changed, and it can be manufactured simply by adjusting the magnetization state of the magnetization fixing layer, thus easily increasing the degree of freedom in magnetic circuit design.

[0094] Furthermore, the shift in the output value of the magnetic sensor 1 when the signal magnetic field is zero can be adjusted by changing the ratio of a portion of the magnetoresistive effect stack 110 to the remaining portion of the plurality of magnetoresistive effect stacks 110 of each of the second magnetoresistive effect element 100 (MR2) and the third magnetoresistive effect element 100 (MR3). This also increases the degree of freedom in magnetic circuit design.

[0095] In the above description of the embodiments, the combinable structures can also be combined with each other.

[0096] The embodiments disclosed herein should be considered illustrative rather than restrictive in all respects. The scope of the invention is set forth not by the foregoing description but by the claims, which are intended to encompass all modifications within the meaning and scope of the claims.

[0097] Explanation of the label

[0098] 1. Magnetic sensor, 1A. First magnetic sensor, 1B. Second magnetic sensor, 10. Position detection device, 20. Magnet, 30. Coil, 100. Magnetoresistive effect element, 110. Magnetoresistive effect stack, 111. Reference layer, 112. Non-magnetic layer, 113. Magnetized free layer, 114. Substrate layer, 115. Antiferromagnetic layer, 116. Pinning layer, 117. Coupling layer, 120. Upper electrode, 130. Lower electrode, A. Differential amplifier, L1. First wiring, L2. Second wiring, L3. Third wiring, L4. Fourth wiring, Ra. First magnetoresistive effect stack, Rb. Second magnetoresistive effect stack.

Claims

1. A magnetic sensor, comprising: First magnetoresistive effect element; Second magnetoresistive element; The third magnetoresistive element; and The fourth magnetoresistive element, The first magnetoresistive element, the second magnetoresistive element, the third magnetoresistive element, and the fourth magnetoresistive element are electrically connected to each other to form a bridge circuit. When a signal magnetic field is applied, the second and third magnetoresistive elements exhibit resistance changes in the opposite direction to those of the first and fourth magnetoresistive elements. The first magnetoresistive element, the second magnetoresistive element, the third magnetoresistive element, and the fourth magnetoresistive element each include multiple magnetoresistive stacks that are electrically connected to each other. In each of the plurality of magnetoresistive effect stacks, a magnetized fixed layer, a non-magnetic layer, and a magnetized free layer whose magnetization direction varies according to the signal magnetic field are stacked sequentially. In each of the first and fourth magnetoresistive effect elements, and in all of the plurality of magnetoresistive effect stacks, the magnetization fixing layer has a magnetization state fixed along a first direction. In a portion of the plurality of magnetoresistive effect stacks, respectively, of the second and third magnetoresistive effect elements, the magnetization fixing layer has a magnetization state fixed along a second direction opposite to the first direction, and the remaining portions of the plurality of magnetoresistive effect stacks include at least one of the following: a portion of the magnetization fixing layer having a magnetization state fixed along a direction different from the second direction; and a portion of the magnetization fixing layer having a magnetization state in which the magnetization direction varies according to the signal magnetic field. The output value when the strength of the signal magnetic field is 0 shifts from 0 due to the difference between the magnetization state of the magnetization fixed layer of the plurality of magnetoresistive effect layers of the first magnetoresistive effect element and the fourth magnetoresistive effect element and the magnetization state of the magnetization fixed layer of the plurality of magnetoresistive effect layers of the second magnetoresistive effect element and the third magnetoresistive effect element.

2. The magnetic sensor according to claim 1, wherein, The maximum resistance values ​​of the plurality of magnetoresistive effect layers of the first magnetoresistive effect element, the second magnetoresistive effect element, the third magnetoresistive effect element, and the fourth magnetoresistive effect element are all equal to each other.

3. The magnetic sensor according to claim 2, wherein, The number of each of the first magnetoresistive effect element, the second magnetoresistive effect element, the third magnetoresistive effect element, and the fourth magnetoresistive effect element is equal to the number of the plurality of magnetoresistive effect stacks.

4. The magnetic sensor according to claim 3, wherein, The plurality of magnetoresistive effect stacks comprising the first magnetoresistive effect element, the second magnetoresistive effect element, the third magnetoresistive effect element, and the fourth magnetoresistive effect element are located in a fourfold rotationally symmetrical position when viewed from the stacking direction of the plurality of magnetoresistive effect stacks.

5. The magnetic sensor according to claim 3, wherein, The plurality of magnetoresistive effect stacks comprising the first magnetoresistive effect element, the second magnetoresistive effect element, the third magnetoresistive effect element, and the fourth magnetoresistive effect element are located in a doubly rotationally symmetrical position when viewed from the stacking direction of the plurality of magnetoresistive effect stacks.

6. A position detection device, comprising: The magnetic sensor according to any one of claims 1 to 5; and A magnet that is movable relative to the magnetic sensor from a reference position. The magnetic sensor is positioned at a location not opposite to the center of the magnet when it is in the reference position, and detects the signal magnetic field applied from the magnet. The output value of the magnetic sensor is 0 when the magnet is located at the reference position.

7. A method for manufacturing a magnetic sensor, comprising: The process of forming the first magnetoresistive element, the second magnetoresistive element, the third magnetoresistive element, and the fourth magnetoresistive element, wherein, The first magnetoresistive element, the second magnetoresistive element, the third magnetoresistive element, and the fourth magnetoresistive element are electrically connected to form a bridge circuit, and each of them contains multiple magnetoresistive effect stacks. Each magnetoresistive effect stack consists of a magnetization fixed layer, a non-magnetic layer, and a magnetization free layer whose magnetization direction changes according to the signal magnetic field. In each of the first and fourth magnetoresistive effect elements, and in all the magnetoresistive effect stacks of the plurality of magnetoresistive effect stacks, the process of making the magnetization fixing layer fixed in a first direction, and... In only a portion of the plurality of magnetoresistive effect stacks of the second and third magnetoresistive effect elements, the magnetization fixing layer is fixed in a second direction opposite to the first direction.

8. The method for manufacturing a magnetic sensor according to claim 7, wherein, In the process of making the magnetization fixing layer fixed in the second direction in only a portion of the plurality of magnetoresistive effect layers of the second magnetoresistive effect element and the third magnetoresistive effect element, a magnetic field in the second direction is applied to all the plurality of magnetoresistive effect layers of the second magnetoresistive effect element and the third magnetoresistive effect element, while heating only a portion of the plurality of magnetoresistive effect layers of the second magnetoresistive effect element and the third magnetoresistive effect element.

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