Manufacturing method of magnetic sensor and the magnetic sensor

Abstract

To provide a manufacturing method of a magnetic sensor capable of adjusting a magnetization direction of a magnetization fixed layer and capable of being easily manufactured.SOLUTION: A manufacturing method of a magnetic sensor includes: a first step (S10) of forming a wiring pattern on a substrate by printing; and a second step (S20) of mounting a magnetoresistive element having a magnetization fixed layer in which a magnetization direction is fixed and a magnetization free layer in which the magnetization direction changes in accordance with a magnetic field on the substrate on which the wiring pattern is formed.SELECTED DRAWING: Figure 6

Description

[Technical Field]

[0001] The present disclosure relates to a method for manufacturing a magnetic sensor and a magnetic sensor. [Background technology]

[0002] Conventionally, magnetic sensors using magnetic sensor elements (magnetoresistive effect elements) that utilize the giant magnetoresistive effect (GMR (Giant Magneto Resistive) effect) have been studied. For example, Patent Document 1 discloses a magnetoresistive effect element that is a differential operation type detection element, and that can set various optimum measurement specifications by arbitrarily changing the magnetic film spacing. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2000-174358 Summary of the Invention [Problem to be solved by the invention]

[0004] However, the magnetic sensor of Patent Document 1 has a problem in that the magnetization direction of the magnetization fixed layer of the magnetoresistive element cannot be adjusted. It is also desirable that the magnetic sensor be easily manufactured.

[0005] Therefore, the present disclosure provides a method for manufacturing a magnetic sensor that is capable of adjusting the magnetization direction of the magnetization fixed layer and that can be easily manufactured, and the magnetic sensor. [Means for solving the problem]

[0006] A method for manufacturing a magnetic sensor according to one embodiment of the present disclosure includes a first step of forming a wiring pattern on a first substrate by printing, and a second step of mounting a magnetoresistive effect element having a magnetization fixed layer whose magnetization direction is fixed and a magnetization free layer whose magnetization direction changes in response to a magnetic field on the first substrate on which the wiring pattern has been formed.

[0007] A magnetic sensor according to one embodiment of the present disclosure comprises a substrate having a wiring pattern formed by printing, and a plurality of magnetoresistive effect elements each having a magnetization fixed layer whose magnetization direction is fixed and a magnetization free layer whose magnetization direction changes in response to a magnetic field, and the plurality of magnetoresistive effect elements are arranged on the substrate such that the magnetization direction of the magnetization fixed layer of at least one of the plurality of magnetoresistive effect elements is different from the magnetization direction of the magnetization fixed layer of at least one other of the plurality of magnetoresistive effect elements. [Effects of the Invention]

[0008] According to one aspect of the present disclosure, it is possible to realize a method for manufacturing a magnetic sensor that is capable of adjusting the magnetization direction of a magnetization fixed layer and is easily manufactured. [Brief explanation of the drawings]

[0009] [Figure 1] FIG. 1 is a plan view showing a magnetic sensor according to an embodiment. [Figure 2] FIG. 2 is a diagram showing a circuit configuration of the magnetic sensor according to the embodiment. [Figure 3] FIG. 3 is a cross-sectional view showing the configuration of the magnetoresistive effect element according to the embodiment, taken along line III-III shown in FIG. [Figure 4] FIG. 4 is a diagram showing the characteristics of the magnetoresistive effect element according to the embodiment. [Figure 5] FIG. 5 is a diagram showing the relationship between the magnetic field and the output voltage of the magnetic sensor according to the embodiment. [Figure 6] FIG. 6 is a flowchart showing a method for manufacturing the magnetic sensor according to the embodiment. [Figure 7] FIG. 7 is a plan view showing a substrate on which wiring is formed by printing according to the embodiment. [Figure 8] FIG. 8 is a flowchart showing step S100 shown in FIG. 6 in detail. [Figure 9]FIG. 9 is a diagram for explaining a heat treatment in the method for manufacturing the magnetic sensor according to the embodiment. [Figure 10] FIG. 10 is a diagram for explaining cutting in the method of manufacturing the magnetic sensor according to the embodiment. [Figure 11] FIG. 11 is a diagram showing the results of a comparison between the magnetic sensor according to the embodiment and other magnetic sensors. [Figure 12] FIG. 12 is a plan view showing a magnetic sensor according to a modified example of the embodiment. [Figure 13] FIG. 13 is a diagram showing the relationship between the angle and the output voltage of the magnetic sensor according to the modified example of the embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0010] (Background to this disclosure) Before describing the present disclosure, the background to the present disclosure will be described.

[0011] Magnetic sensors are important sensors used in a variety of applications, including magnetocardiograms, magnetoencephalograms, compass readings, and magnetic material detection. Among these magnetic sensors, magnetic sensors using giant magnetoresistance elements are well known. Giant magnetoresistance elements have a fixed magnetization layer whose magnetization direction is fixed relative to an external magnetic field, and a free magnetization layer whose magnetization direction rotates relative to the external magnetic field. Such magnetic sensors can be used to detect the direction of an external magnetic field. The magnetization direction refers to the direction of the magnetic flux flowing inside.

[0012] Magnetic sensors are typically incorporated into products, components, etc., and the positional relationship between the source of an external magnetic field and the magnetic sensor is generally determined by the design of the product or component. Therefore, the direction of the external magnetic field applied to the magnetization free layer of the magnetic sensor may differ from product to product. Therefore, it is desirable to be able to adjust the magnetization direction of the magnetization fixed layer of the magnetoresistive element of the magnetic sensor as needed depending on the product.

[0013] However, in the technology of the above-mentioned patent document, after wiring and a magnetic layer are formed on a substrate that constitutes a magnetic sensor, heat treatment (i.e., fixing the magnetization direction in the magnetization fixed layer) is performed in a magnetic field. Therefore, for example, when multiple magnetoresistance effect elements are arranged, the magnetization direction of the magnetization fixed layer cannot be adjusted arbitrarily.

[0014] Furthermore, it is desirable that a magnetic sensor using a magnetoresistive element be easily manufactured.

[0015] Therefore, as a further improvement to magnetic sensors having magnetoresistive effect elements, the inventors of the present application have conducted extensive research into a manufacturing method for a magnetic sensor and a magnetic sensor that can adjust the magnetization direction of the magnetization fixed layer of the magnetoresistive effect element and can be easily manufactured, and have devised the manufacturing method and magnetic sensor shown below.

[0016] A method for manufacturing a magnetic sensor according to a first aspect of the present disclosure includes a first step of forming a wiring pattern on a first substrate by printing, and a second step of mounting a magnetoresistive effect element having a magnetization fixed layer whose magnetization direction is fixed and a magnetization free layer whose magnetization direction changes in response to a magnetic field on the first substrate on which the wiring pattern has been formed.

[0017] As a result, the magnetoresistive element is mounted on the first substrate after the wiring pattern is formed, and the magnetization direction of the magnetization fixed layer of the magnetoresistive element can be adjusted as desired by adjusting the mounting orientation of the magnetoresistive element. Also, since the wiring pattern is formed by printing, it can be manufactured more easily than when the wiring pattern is formed by photolithography or the like. Therefore, a manufacturing method for a magnetic sensor that is capable of adjusting the magnetization direction of the magnetization fixed layer and is easy to manufacture can be realized.

[0018] Also, for example, a method for manufacturing a magnetic sensor according to a second aspect of the present disclosure may be a method for manufacturing a magnetic sensor according to the first aspect, wherein in the second step, the plurality of magnetoresistive effect elements are mounted on the first substrate so that the magnetization direction of the magnetization fixed layer of at least one of the plurality of magnetoresistive effect elements is different from the magnetization direction of the magnetization fixed layer of at least one other of the plurality of magnetoresistive effect elements.

[0019] This makes it possible to easily manufacture magnetic sensors with various performance characteristics simply by changing the magnetization direction (that is, the mounting direction) of the magnetoresistive element.

[0020] Also, for example, a method for manufacturing a magnetic sensor according to a third aspect of the present disclosure may be a method for manufacturing a magnetic sensor according to the second aspect, in which the plurality of magnetoresistive effect elements include four of the magnetoresistive effect elements, and in the second step, a bridge circuit having the four magnetoresistive effect elements is formed.

[0021] This makes it possible to easily manufacture a magnetic sensor having a bridge circuit.

[0022] Furthermore, for example, a method for manufacturing a magnetic sensor according to a fourth aspect of the present disclosure may be a method for manufacturing a magnetic sensor according to the third aspect, wherein in the second step, four magnetoresistive effect elements are mounted on the first substrate so that the magnetization directions of the magnetoresistive effect elements positioned opposite each other in the bridge circuit are in the same direction.

[0023] This makes it possible to easily fabricate a magnetic sensor capable of obtaining a change in electrical resistance when a magnetic field of both positive and negative polarities (bipolarity) is applied.

[0024] Furthermore, for example, a manufacturing method of a magnetic sensor according to a fifth aspect of the present disclosure may be a manufacturing method of a magnetic sensor according to any one of the second to fourth aspects, wherein the plurality of magnetoresistive effect elements include four first magnetoresistive effect elements and four second magnetoresistive effect elements, and in the second step, a first bridge circuit having the four first magnetoresistive effect elements and a second bridge circuit having the four second magnetoresistive effect elements, the second bridge circuit being connected to a common power supply with the first bridge circuit, may be formed, and the magnetization direction of the magnetization fixed layer of the four first magnetoresistive effect elements constituting the first bridge circuit may intersect with the magnetization direction of the magnetization fixed layer of the four second magnetoresistive effect elements constituting the second bridge circuit.

[0025] This makes it possible to detect the relative angle between the magnetic field direction and the magnetic sensor, thereby realizing a more accurate magnetic sensor.

[0026] Furthermore, for example, a method for manufacturing a magnetic sensor according to a sixth aspect of the present disclosure may be a method for manufacturing a magnetic sensor according to any one of the first to fifth aspects, further comprising a third step of manufacturing the magnetoresistive effect element by cutting a laminate in which a magnetization fixed layer, a non-magnetic layer, and a magnetization free layer are stacked on a second substrate.

[0027] As a result, since the magnetoresistive effect element fabricated in a step different from the first step is used, the magnetization direction of the magnetization fixed layer can be easily adjusted in the mounting direction.

[0028] Furthermore, for example, a method for manufacturing a magnetic sensor according to a seventh aspect of the present disclosure may be the method for manufacturing a magnetic sensor according to the sixth aspect, in which the second substrate is flexible.

[0029] This allows the laminate to be easily cut, making it possible to fabricate the magnetoresistive element even more easily.

[0030] Furthermore, for example, a method for manufacturing a magnetic sensor according to an eighth aspect of the present disclosure may be a method for manufacturing a magnetic sensor according to the sixth or seventh aspect, wherein the third step further includes stacking a first ferromagnetic layer, a non-magnetic layer, and a second ferromagnetic layer on the second substrate, and performing a heat treatment on the second substrate in a magnetic field to fix the magnetization direction of the second ferromagnetic layer, thereby forming the laminate.

[0031] This allows the laminate to be produced in a third step that is separate from the first step.

[0032] Also, for example, a method for manufacturing a magnetic sensor according to a ninth aspect of the present disclosure may be a method for manufacturing a magnetic sensor according to any one of the first to eighth aspects, in which the wiring pattern is formed by inkjet printing in the first step.

[0033] This makes it possible to easily form a wiring pattern by a simple method such as inkjet printing, without requiring any special equipment.

[0034] Furthermore, for example, a method for manufacturing a magnetic sensor according to a tenth aspect of the present disclosure is the method for manufacturing a magnetic sensor according to any one of the first to ninth aspects, and the first substrate may be flexible.

[0035] This makes it possible to realize a flexible magnetic sensor.

[0036] Also, for example, a method for manufacturing a magnetic sensor according to an eleventh aspect of the present disclosure may be a method for manufacturing a magnetic sensor according to any one of the first to tenth aspects, in which in the second step, a plurality of the magnetoresistive effect elements are mounted on the same plane.

[0037] This makes it possible to prevent the detection performance of the magnetic sensor from being reduced.

[0038] In addition, a magnetic sensor according to a twelfth aspect of the present disclosure comprises a substrate having a wiring pattern formed by printing, and a plurality of magnetoresistive effect elements having a magnetization fixed layer whose magnetization direction is fixed and a magnetization free layer whose magnetization direction changes in response to a magnetic field, and the plurality of magnetoresistive effect elements are arranged on the substrate so that the magnetization direction of the magnetization fixed layer of at least one of the plurality of magnetoresistive effect elements is different from the magnetization direction of the magnetization fixed layer of at least one other of the plurality of magnetoresistive effect elements.

[0039] This provides the same effects as the above-described method for manufacturing a magnetic sensor.

[0040] Hereinafter, embodiments and the like will be specifically described with reference to the drawings.

[0041] The embodiments and the like described below are all comprehensive or specific examples. The numerical values, shapes, components, component placement and connection configurations, steps, and step sequences shown in the following embodiments are merely examples and are not intended to limit the present disclosure. Furthermore, among the components in the following embodiments and the like, components that are not recited in independent claims are described as optional components.

[0042] Furthermore, each figure is a schematic diagram and is not necessarily an exact illustration. Therefore, for example, the scales of the figures do not necessarily match. Furthermore, in each figure, substantially the same components are given the same reference numerals, and redundant explanations are omitted or simplified.

[0043] In this specification and the drawings, the X-axis, Y-axis, and Z-axis represent the three axes of a right-handed three-dimensional Cartesian coordinate system. In the embodiments, the Z-axis direction is the stacking direction of each layer of the magnetoresistive element. In this specification, the term "planar view" means viewing the magnetoresistive element or magnetic sensor along the stacking direction of each layer of the magnetoresistive element.

[0044] Furthermore, in this specification, terms indicating the relationship between elements, such as orthogonal, terms indicating the shape of elements, such as rectangle and square, as well as numerical values ​​and numerical ranges, are not expressions that express only the strict meaning, but are expressions that also include a substantially equivalent range, for example, a difference of about a few percent (or about 10%).

[0045] Furthermore, in this specification, the term "on ____ (e.g., on a substrate)" does not refer to the upward direction (vertically upward) or downward direction (vertically downward) in absolute spatial recognition, but is used as a term defined by a relative positional relationship based on the stacking order in a stacked configuration. Furthermore, the term "on ____ (e.g., on a substrate)" applies not only to cases where two components are arranged with a gap between them and another component exists between the two components, but also to cases where two components are arranged in contact with each other.

[0046] Furthermore, in this specification, ordinal numbers such as "first" and "second" do not refer to the number or order of components unless otherwise specified, but are used for the purpose of avoiding confusion and distinguishing between components of the same type.

[0047] Furthermore, the "connection" of each component means an electrical connection, and includes not only a direct connection between two components, but also an indirect connection between two components with another component inserted between them.

[0048] (Embodiment) Hereinafter, a magnetic sensor and a method for manufacturing the magnetic sensor according to the present embodiment will be described with reference to FIGS.

[0049] [1. Magnetic sensor configuration] First, the configuration of the magnetic sensor according to this embodiment will be described with reference to FIGS. 1 to 5. FIG. 1 is a plan view showing a magnetic sensor 100 according to this embodiment. The arrows shown in FIG. 1 indicate the magnetization direction of the magnetization fixed layer (see FIG. 3 described later) of the magnetoresistive effect element. Hereinafter, the magnetization direction of the magnetization fixed layer will also be referred to as the pinned direction. The pinned direction will also be referred to as the fixed magnetization direction.

[0050] As shown in FIG. 1, the magnetic sensor 100 includes a substrate 10, wires L1 to L4, and magnetoresistive elements 21 to 24. The magnetic sensor 100 is a magnetic sensor that utilizes the magnetoresistive effect. In this embodiment, the magnetic sensor 100 includes four magnetoresistive elements 21 to 24. Note that FIG. 1 does not illustrate a power supply, a voltmeter, lead wires connecting the power supply and voltmeter to the wires L1 to L4, and bonding members such as solder and conductive adhesive for mounting the magnetoresistive elements 21 to 24 on the substrate 10. Also, in FIG. 1, the connection between the magnetoresistive elements and the wires is shown as overlapping the magnetoresistive elements and the wires, but the magnetoresistive elements and the wires are not limited to overlapping.

[0051] The substrate 10 is a substrate on which wirings L1 to L4 are formed and magnetoresistive effect elements 21 to 24 are mounted. In this embodiment, the substrate 10 is a flexible substrate having flexibility. An example of a flexible substrate is a resin sheet such as a PET (Polyethylene Terephthalate) sheet, but is not limited to this. The substrate 10 may also be a rigid substrate. The substrate 10 is an example of a first substrate.

[0052] The mounting may involve joining the wiring and the magnetoresistive element using solder or the like, or may involve attaching the magnetoresistive element to the wiring using a conductive adhesive or the like.

[0053] The wirings L1 to L4 are conductive layers formed on the substrate 10. The wirings L1 to L4 are formed so as to form a bridge circuit (Wheatstone bridge) with the magnetoresistive effect elements 21 to 24 mounted thereon. In this embodiment, the wirings L1 to L4 are formed by printing using a conductive material, but may also be formed by photolithography, for example.

[0054] The magnetoresistive elements 21 to 24 are magnetic sensor elements that utilize the GMR effect, and have the property that their electrical resistance varies depending on the direction of a magnetic field. In this embodiment, the magnetoresistive elements 21 to 24 are connected to each other by a bridge circuit. The magnetoresistive elements 21 and 24 have the same magnetization direction (the direction on the negative side of the Y-axis in the example of FIG. 1), and the magnetoresistive elements 22 and 23 have the same magnetization direction (the direction on the positive side of the Y-axis in the example of FIG. 1). The magnetoresistive elements 21 and 24 have magnetization directions that differ by 180 degrees from the magnetoresistive elements 22 and 23.

[0055] The shape of the magnetoresistance effect elements 21 to 24 in plan view is, for example, rectangular, but is not limited to this and may be any other shape such as square.

[0056] The circuit configuration of the magnetic sensor 100 configured as above will be further described with reference to Fig. 2. Fig. 2 is a diagram showing the circuit configuration of the magnetic sensor 100 according to this embodiment.

[0057] As shown in FIGS. 1 and 2, magnetoresistive effect elements 21 and 23 are connected in series, magnetoresistive effect elements 22 and 24 are connected in series, and these are connected in parallel to each other to form a bridge circuit.

[0058] In this way, the magnetic sensor 100 is configured so that the pin directions of the two magnetoresistive effect elements connected in series are different from each other. Note that the magnetic sensor 100 only needs to be configured so that the pin direction of at least one of the magnetoresistive effect elements 21 to 24 is different from the pin directions of the other magnetoresistive effect elements.

[0059] For example, if the wire L2 is connected to the positive side of the power supply, the wire L4 is connected to the ground side of the power supply, and the wires L1 and L3 are connected to a voltmeter, the potential difference V between a and b can be calculated by the following formula 1, where E is the voltage of the power supply and R21 to R24 are the electrical resistances of the magnetoresistive elements 21 to 24.

[0060] V=E×(R24 / (R22+R24)-R23 / (R21+R23)) (Formula 1)

[0061] Here, the cross-sectional configuration of the magnetoresistive effect elements 21 to 24 will be described with reference to Fig. 3. Fig. 3 is a cross-sectional view showing the configuration of the magnetoresistive effect element 21 according to this embodiment, taken along the III-III cutting line shown in Fig. 1. The configuration of the magnetoresistive effect elements 22 to 24 is the same as that of the magnetoresistive effect element 21, and therefore a description thereof will be omitted.

[0062] 3, the magnetoresistive effect element 21 includes a polyimide substrate 31, a magnetization fixed layer 32, a non-magnetic layer 33, and a magnetization free layer 34. The magnetoresistive effect element 21 has a layered structure in which the magnetization fixed layer 32, the non-magnetic layer 33, and the magnetization free layer 34 are stacked on the polyimide substrate 31. Note that the positions of the magnetization fixed layer 32 and the magnetization free layer 34 in the stacking direction may be reversed.

[0063] The polyimide substrate 31 is a flexible substrate. In this embodiment, the polyimide substrate 31 is made of a polyimide film or the like. The substrate of the magnetoresistive element 21 may be made of other flexible resin films or paper or the like. The polyimide substrate 31 may also be a rigid substrate.

[0064] The magnetization fixed layer 32 is a layer (pinned layer) made of a ferromagnetic material and provided on the polyimide substrate 31. The magnetization direction of the magnetization fixed layer 32 is fixed during the manufacturing stage. In this embodiment, the magnetization fixed layer 32 is made of a CoFe / IrMn laminated structure, but is not limited to this. The magnetization fixed layer 32 may also contain materials such as Al, Si, Pt, and B.

[0065] The non-magnetic layer 33 is provided between the magnetization fixed layer 32 and the magnetization free layer 34, and functions as a spin transport layer. The non-magnetic layer 33 is made of a material (non-magnetic material) that can transport spin current. In this embodiment, the non-magnetic layer 33 is made of a non-magnetic metal such as copper (Cu), but it may also be made of other non-magnetic metals that do not substantially have magnetism (e.g., Al, C, Zn, Ti).

[0066] The magnetization free layer 34 is a layer (free layer) made of a ferromagnetic material and provided on the non-magnetic layer 33. The magnetization direction of the magnetization free layer 34 is not fixed during manufacturing, but can change in response to a magnetic field (in response to the magnetic field direction). Specifically, the magnetization direction of the magnetization free layer 34 changes in the same direction as the magnetic field direction in a magnetic field. In this embodiment, the magnetization free layer 34 has a NiFe / CoFe laminated structure, but is not limited to this. The magnetization free layer 34 may also be made of a soft magnetic material such as Fe—Si—Al or Co—Fe—B.

[0067] In this way, the magnetoresistive element 21 has a flexible magnetic multilayer film structure.

[0068] As described above, the magnetic sensor 100 includes a substrate 10 having a wiring pattern formed by printing, and a plurality of magnetoresistive effect elements 21-24 each having a magnetization fixed layer 32 whose magnetization direction is fixed and a magnetization free layer 34 whose magnetization direction changes in response to a magnetic field. The plurality of magnetoresistive effect elements 21-24 are arranged on the substrate 10 such that the magnetization direction of the magnetization fixed layer 32 of at least one of the plurality of magnetoresistive effect elements 21-24 is different from the magnetization direction of the magnetization fixed layer 32 of at least one other of the plurality of magnetoresistive effect elements.

[0069] In the magnetic sensor 100, the magnetization direction of the magnetization fixed layer 32, which is a ferromagnetic layer, is fixed, so the magnetization direction of the magnetization free layer 34, which is sensitive to external magnetic fields, can be read as a change in electrical resistance. For example, the electrical resistance of the magnetoresistive element 21 changes as the degree of electron scattering changes between the antiparallel magnetization state and the parallel magnetization state. Specifically, the magnetoresistive element 21 has high electrical resistance when in the antiparallel magnetization state and low electrical resistance when in the parallel magnetization state. The magnetic sensor 100 can convert changes in magnetic fields, etc. into electrical signals by utilizing these characteristics of the magnetoresistive elements 21 to 24.

[0070] [2. Magnetic sensor characteristics] Next, various characteristics of the magnetic sensor 100 having the flexible bridge circuit configured as described above will be described with reference to Fig. 4 and Fig. 5. Fig. 4 is a diagram showing the electrical resistance characteristics of the magnetoresistive effect elements 21 to 24 according to this embodiment. Fig. 4(a) is a diagram showing the electrical resistance in the antiparallel magnetization state and the parallel magnetization state, with the vertical axis representing the electrical resistance and the horizontal axis representing the strength of the magnetic field.

[0071] As shown in (a) of Figure 4, the electrical resistance in the antiparallel magnetization state is approximately 2.7% higher than the electrical resistance in the parallel magnetization state, and magnetic sensor 100 can obtain a large change in output voltage.

[0072] Figure 4(b) is a graph showing the change in electrical resistance when a permanent magnet is moved closer to and away from the magnetoresistive elements 21 to 24, with the vertical axis representing electrical resistance and the horizontal axis representing time. In Figure 4(b), the permanent magnet is moved closer to the magnetoresistive elements 21 to 24 three times.

[0073] As shown in (b) of Figure 4, the electrical resistance changes when a magnetic body such as a permanent magnet is brought close to the magnetoresistance effect element 21, and it can be seen that a magnetic sensor 100 equipped with such a magnetoresistance effect element 21 can detect the position of the magnetic body.

[0074] FIG. 5 is a diagram showing the relationship between the magnetic field and the output voltage of the magnetic sensor 100 according to this embodiment. The vertical axis of FIG. 5 represents the output voltage Vout, and the horizontal axis represents the magnetic flux density, i.e., the strength of the magnetic field. The output voltage Vout is a voltage value measured by the voltmeter shown in FIG. 2. Note that the magnetic field direction in the magnetic field H is such that the negative side of the Y-axis direction shown in FIG. 1 is positive, and the positive side of the Y-axis direction shown in FIG. 1 is negative. Note that the power supply voltage Vin is 40 mV.

[0075] As shown in FIG. 5, when the magnetic flux density changes from negative to positive, that is, when the magnetic field direction changes from a direction toward the positive side of the Y axis to a direction toward the negative side of the Y axis, the output voltage Vout also changes accordingly.

[0076] In this way, the magnetic sensor 100 having a flexible bridge circuit can read out magnetic signals with high sensitivity.

[0077] 5 illustrates a case where the substrate 10 is a flexible substrate, but it is believed that similar characteristics can be obtained even if the substrate 10 is a rigid substrate. Also, while FIGS. 4 and 5 illustrate a case where the substrate of the magnetoresistive effect elements 21 to 24 is a polyimide substrate 31, it is believed that similar characteristics can be obtained even if a rigid substrate is used instead of the polyimide substrate 31.

[0078] [3. Manufacturing method of magnetic sensor] Next, a method for manufacturing the magnetic sensor 100 configured as above will be described with reference to Fig. 6 to Fig. 10. Fig. 6 is a flowchart showing the method for manufacturing the magnetic sensor 100 according to this embodiment. The method for manufacturing the magnetic sensor 100 is characterized in that the formation of the wirings L1 to L4 on the substrate 10 and the fabrication of the magnetoresistive effect elements 21 to 24 are performed in separate steps.

[0079] As shown in FIG. 6, first, a wiring pattern is printed on a first substrate (substrate 10, which is a PET sheet in this embodiment) using an inkjet printer (S10). For example, ink containing a conductive metal (e.g., silver (Ag)) is printed on substrate 10 using an inkjet printer to form wirings L1 to L4. The pattern for printing the ink is obtained in advance. Note that the conductive metal is not limited to Ag, and may be Cu or the like. Step S10 is an example of a first process.

[0080] As described above, in this embodiment, the wirings L1 to L4 are formed by inkjet circuit forming technology, which uses ink containing metal fine particles to form a wiring pattern by an inkjet printer method.

[0081] The inkjet printer may be a commercially available inkjet printer, or may be an inkjet printer sold for industrial use.

[0082] It should be noted that step S10 is not limited to printing using an inkjet printer, and may be performed by other printing methods such as screen printing.

[0083] FIG. 7 is a plan view showing the substrate 10 on which wirings L1 to L4 are formed by printing according to the present embodiment.

[0084] 7, the wirings L1 to L4 are formed by inkjet printing on the substrate 10. At this point, the magnetoresistive effect elements 21 to 24 have not yet been formed on the substrate 10.

[0085] Referring again to FIG. 6, next, the magnetoresistive effect elements fabricated in step S100 are mounted on the substrate 10 on which the wirings L1 to L4 have been formed, with the magnetization directions (pinning directions) of the magnetization fixed layers of the magnetoresistive effect elements fabricated in step S100 being different (S20). That is, in step S20, magnetoresistive effect elements fabricated in a separate process, i.e., magnetoresistive effect elements 21 to 24 on which the magnetization fixed layer 32 has already been formed, are mounted on the substrate 10 on which the wirings L1 to L4 have already been formed. In this embodiment, the four magnetoresistive effect elements 21 to 24 are mounted on the substrate 10 so that the pinning directions of the magnetoresistive effect elements located diagonally in the bridge circuit are aligned and opposite to the pinning directions of the magnetoresistive effect elements located on the other diagonals. In this way, the magnetic sensor 100 shown in FIG. 1 is fabricated. Step S20 is an example of the second process.

[0086] Note that the diagonal positions in the bridge circuit can also be referred to as opposing positions in the bridge circuit. Opposing positions in the bridge circuit refer to the position between one of the four magnetoresistive effect elements 21 to 24 and another magnetoresistive effect element that is not adjacent to the one magnetoresistive effect element. For example, taking the magnetoresistive effect element 21 as an example, the elements adjacent to the magnetoresistive effect element 21 are magnetoresistive effect elements 22 and 23, and the element that is not adjacent to the magnetoresistive effect element 21 is magnetoresistive effect element 24. In other words, the magnetoresistive effect elements 21 and 24 are arranged in opposing positions in the bridge circuit, and the magnetoresistive effect elements 22 and 23 are arranged in opposing positions in the bridge circuit.

[0087] The magnetoresistance effect elements 21 to 24 are mounted, for example, at positions on the same plane on the substrate 10. For example, the substrate 10 is used in a flat state (that is, without being bent).

[0088] The substrate 10 on which the magnetoresistive elements 21 to 24 are mounted is not subjected to heat treatment in a magnetic field for forming the magnetization fixed layers of the magnetoresistive elements 21 to 24.

[0089] Fig. 8 is a flowchart showing in detail step S100 shown in Fig. 6. Fig. 9 is a diagram for explaining heat treatment in the manufacturing method of the magnetic sensor 100 according to this embodiment. Fig. 9 is a cross-sectional view, but hatching is omitted for convenience. Step S100 is an example of the third step.

[0090] As shown in Fig. 8, first, a polyimide substrate 231 (see Fig. 9) such as a polyimide film is prepared (S110). The polyimide film has a size that allows multiple magnetoresistive effect elements to be fabricated, and is in a sheet or roll shape. The polyimide substrate 231 is an example of a second substrate.

[0091] Next, each layer is formed on the polyimide substrate 231 (S120). Specifically, a ferromagnetic layer 232, a non-magnetic layer 233, and a ferromagnetic layer 234 (see FIG. 9) are laminated in this order on the polyimide substrate 231. The method for forming the ferromagnetic layer 232, the non-magnetic layer 233, and the ferromagnetic layer 234 is not particularly limited, but a sputtering method is exemplified. At this point, the magnetization direction of the ferromagnetic layer 232 is not fixed. The ferromagnetic layer 232 is an example of a first ferromagnetic layer, and the ferromagnetic layer 234 is an example of a second ferromagnetic layer.

[0092] Next, the magnetization direction of the magnetization fixed layer is fixed (S130). Specifically, the polyimide substrate 231 on which the ferromagnetic layer 232, the non-magnetic layer 233, and the ferromagnetic layer 234 are formed is subjected to a heat treatment in a magnetic field with a constant magnetic field direction, thereby fixing the magnetization direction of one of the two ferromagnetic layers 232 and 234 to the magnetic field direction. The heat treatment may be performed, for example, on a sheet-by-sheet basis.

[0093] As a result, a laminate 230 is formed in which the magnetization direction of one of the ferromagnetic layers 232 and 234 is fixed, as shown in Fig. 9. Fig. 9 shows an example in which the magnetization direction of the ferromagnetic layer 232 on the polyimide substrate 231 side is fixed.

[0094] Next, the laminate 230 that has been subjected to step S130 is cut to a predetermined size (S140). By cutting the laminate 230 to a predetermined size, the magnetoresistive effect elements 21 to 24 are formed. The magnetization fixed layer 32 is formed by the ferromagnetic layer 232 whose magnetization direction is fixed, the non-magnetic layer 33 is formed by the non-magnetic layer 233, and the magnetization free layer 34 is formed by the ferromagnetic layer 234.

[0095] 10 is a diagram for explaining cutting in the manufacturing method of the magnetic sensor 100 according to this embodiment. In FIG. 10, the polyimide substrate 231 is in a sheet form, and a cutting machine 300 is used to cut the polyimide substrate 231.

[0096] 10, in step S140, the laminate 230 is cut using a cutting machine 300 or the like to produce the magnetoresistive effect elements 21 to 24. Note that a laser processing machine, scissors, or the like may be used instead of the cutting machine 300. In this embodiment, a flexible substrate such as the polyimide substrate 231 is used, which can be easily cut using the cutting machine 300 or the like.

[0097] Note that, before or after step S140, a mark indicating the pin direction of the magnetoresistive effect element may be attached to each of the cut magnetoresistive effect elements. The mark may be a mark indicating the pin direction. Furthermore, the magnetoresistive effect elements may be cut into a shape that allows the pin direction to be identified.

[0098] In conventional magnetic sensors, wiring and magnetoresistive elements are patterned together using photolithography or other methods, and then heat-treated in a magnetic field. As a result, the pins of the magnetoresistive elements in the magnetic sensor all face the same direction, and electrical resistance changes can only be observed when a magnetic field of either positive or negative polarity is applied.

[0099] On the other hand, in the magnetic sensor 100 according to this embodiment, in order to set the pin directions of the magnetoresistive effect elements 21 to 24 in the bridge circuit in any direction, the magnetoresistive effect elements 21 to 24 are fabricated in a process separate from the formation of the wirings L1 to L4, and the mounting directions (i.e., pin directions) of the magnetoresistive effect elements 21 to 24 are adjusted when they are mounted on the substrate 10. For example, by aligning the pin directions of the magnetoresistive effect elements on diagonal corners in the bridge circuit, it is possible to realize the magnetic sensor 100 that can obtain a change in electrical resistance when magnetic fields of both positive and negative polarities (bipolar) are applied.

[0100] [4. Comparison with other magnetic sensors] Next, a comparison between the magnetic sensor 100 configured as described above and other magnetic sensors will be described with reference to FIG. 11. FIG. 11 is a diagram showing the results of a comparison between the magnetic sensor 100 according to this embodiment and other magnetic sensors. FIG. 11 illustrates a Hall IC (Integrated Circuit) and an AMR (Anisotropic Magneto Resistive) sensor as examples of other magnetic sensors. The Hall IC is a magnetic sensor that applies the Hall effect and detects a magnetic field by detecting a voltage (Hall voltage) generated by Lorentz force in a direction perpendicular to the current and magnetic field direction. The AMR sensor is a magnetic sensor that uses the phenomenon in which electrical resistance changes depending on the strength of the magnetic field and detects a magnetic field using a flowing current.

[0101] 11 also shows the evaluation items of sensitivity, polarity, and fabrication. Sensitivity refers to the accuracy of detecting a magnetic field, polarity refers to the polarity of the magnetic field that can be detected, and fabrication mainly refers to the ease of manufacturing. Note that the sensitivity of the magnetic sensor 100 is shown as a value without an amplifier.

[0102] 11, the sensitivity is "good" for the Hall IC, the AMR sensor, and the magnetic sensor 100. Specifically, the Hall IC outputs 50 mV at 10 mT for an input voltage (power supply voltage) of 1 V, the AMR sensor outputs 3 V at 4 mT for an input voltage of 3 V, and the magnetic sensor 100 outputs 10 mV at 10 mT for an input voltage of 1 V.

[0103] Regarding polarity, bipolarity is marked with "O" and unipolarity is marked with "X".

[0104] The Hall IC and magnetic sensor 100 are marked with "◯" because they can detect both polarities. The AMR sensor is unipolar so is marked with "X".

[0105] In terms of manufacturing, if the manufacturing is easy, it is marked with "◎", and if the manufacturing is not easy, it is marked with "△".

[0106] Hall ICs are marked "△" because they require a single semiconductor crystal to be made and are not easy to manufacture.

[0107] AMR sensors require patterning and are not easy to manufacture, so they are marked "△".

[0108] The magnetic sensor 100 does not require a semiconductor single crystal or patterning, and wiring is produced by inkjet printing, so it is easy to manufacture and is marked with "Excellent."

[0109] As described above, the magnetic sensor 100 has evaluation results that are superior to conventional magnetic sensors in all aspects of sensitivity, polarity, and fabrication. The magnetic sensor 100 can achieve both sensor performance as indicated by sensitivity and polarity and ease of manufacturing as indicated by fabrication.

[0110] (Modification of the embodiment) The magnetic sensor according to this modification will be described below with reference to Fig. 12 and Fig. 13. The following description will focus on differences from the embodiment, and descriptions of the same or similar aspects as the embodiment will be omitted or simplified.

[0111] FIG. 12 is a plan view showing a magnetic sensor 100a according to this modification. In this modification, a configuration will be described in which the magnetic sensor 100a is used as an angle sensor that detects the relative angle between the magnetic field direction and the magnetic sensor 100a. For example, the magnetic sensor 100a is described as detecting the angle of the magnetic sensor 100a when the magnetic sensor 100a arranged in a static magnetic field rotates around a rotation axis perpendicular to the substrate 10a, or the magnetic field direction when the magnetic sensor 100a is fixed and the magnetic field direction changes. Note that in the two dot-dash circles shown in FIG. 12, the intersecting wiring and the magnetoresistive effect element are not connected. Also, the arrows around the symbol of the magnetoresistive effect element in FIG. 12 indicate the pin direction of the magnetoresistive effect element.

[0112] 12, the magnetic sensor 100a according to this modification includes a substrate 10a, wirings L11 to L16, and eight magnetoresistance effect elements 21a to 28a. The magnetic sensor 100a also includes two bridge circuits: a first bridge circuit C1 and a second bridge circuit C2.

[0113] The substrate 10a is a substrate on which the wirings L11 to L16 are formed and the magnetoresistive effect elements 21a to 28a are mounted. In this modification, the substrate 10a is a flexible substrate such as a PET sheet, but may also be a rigid substrate.

[0114] The wirings L11 to L16 are conductive layers formed on the substrate 10a. The wirings L11 to L14 are formed to configure a first bridge circuit C1 when the magnetoresistive elements 21a to 24a are mounted thereon, and the wirings L11, L12, L15, and L16 are formed to configure a second bridge circuit C2 when the magnetoresistive elements 25a to 28a are mounted thereon.

[0115] Furthermore, the wire L11 is connected to the positive side of a power supply (not shown), the wire L12 is connected to the ground side of the power supply, the wire L13 is connected to the positive terminal of a first voltmeter (not shown), the wire L14 is connected to the negative terminal of the first voltmeter, the wire L15 is connected to the positive terminal of a second voltmeter (not shown), and the wire L16 is connected to the negative terminal of the second voltmeter.

[0116] The power supply outputs a desired voltage. The first voltmeter measures the differential voltage between voltages Vout0+ and Vout0- (voltage Vout0 shown in FIG. 13, which will be described later). The second voltmeter measures the differential voltage between voltages Vout90+ and Vout90- (voltage Vout90 shown in FIG. 13, which will be described later). The first and second voltmeters may be separate voltmeters or may be a single voltmeter.

[0117] In this modification, the wirings L11 to L16 are formed by printing using a conductive material, but may also be formed by, for example, photolithography.

[0118] The first bridge circuit C1 is composed of a portion of the wirings L11 and L12, wirings L13 and L14, and four magnetoresistive effect elements 21a to 24a. In the first bridge circuit C1, the magnetoresistive effect elements 21a and 23a are connected in series, and the magnetoresistive effect elements 22a and 24a are connected in series, and these are connected in parallel to each other to form a single bridge circuit. The magnetoresistive effect elements 21a and 24a have the same pin orientation, for example, facing downward in the drawing, and the magnetoresistive effect elements 22a and 23a have the same pin orientation and are opposite to the pin orientation of the magnetoresistive effect elements 21a and 24a, for example, facing upward in the drawing.

[0119] The magnetoresistive element 21a is connected to the wirings L11 and L13, the magnetoresistive element 22a is connected to the wirings L11 and L14, the magnetoresistive element 23a is connected to the wirings L12 and L13, and the magnetoresistive element 24a is connected to the wirings L12 and L14.

[0120] The second bridge circuit C2 is composed of a portion of the wirings L11 and L12, wirings L15 and L16, and four magnetoresistive elements 25a to 28a. In the second bridge circuit C2, the magnetoresistive elements 25a and 27a are connected in series, and the magnetoresistive elements 26a and 28a are connected in series, and these are connected in parallel to each other to form another bridge circuit. The magnetoresistive elements 25a and 28a have the same pin orientation, for example, pointing right on the page, and the magnetoresistive elements 26a and 27a have the same pin orientation but facing opposite to the pin orientation of the magnetoresistive elements 25a and 28a, for example, pointing left on the page.

[0121] The first bridge circuit C1 and the second bridge circuit C2 are connected to a common power source and are connected in parallel.

[0122] The magnetoresistive effect element 25a is connected to the wirings L11 and L16, the magnetoresistive effect element 26a is connected to the wirings L11 and L15, the magnetoresistive effect element 27a is connected to the wirings L12 and L16, and the magnetoresistive effect element 28a is connected to the wirings L12 and L15.

[0123] 3, and have the same structure and function as the magnetoresistive effect elements 21 to 24. The magnetoresistive effect elements 21a to 24a are an example of a first magnetoresistive effect element, and the magnetoresistive effect elements 25a to 28a are an example of a second magnetoresistive effect element.

[0124] As described above, the first pin directions of the magnetoresistive effect elements 21a to 24a and the second pin directions of the magnetoresistive effect elements 25a to 28a intersect in plan view, and in this modification, they intersect at an angle of 90 degrees. Note that the intersect is not limited to an intersect at 90 degrees, and may intersect at another angle.

[0125] Fig. 13 is a diagram showing the relationship between the angle θ and the output voltage Vout of the magnetic sensor 100a according to this modification, when the voltage Vin is 5 mV, the magnetic flux density μOH of the static magnetic field is 10 mT, and the magnetic sensor 100a rotates around a rotation axis that is perpendicular to the magnetic field direction.

[0126] 13, in the magnetic sensor 100a, the first bridge circuit C1 and the second bridge circuit C2 have a 90-degree difference in response to the magnetic field. Specifically, the voltages Vout0 and Vout90 are out of phase with each other by 90 degrees. This makes it possible to determine the relative angle θ between the magnetic sensor 100a and the magnetic field direction by measuring the values ​​of the voltages Vout0 and Vout90.

[0127] The magnetic sensor 100a configured as described above is manufactured according to the flowchart of the embodiment shown in Fig. 6. Specifically, in step S10 shown in Fig. 6, a wiring pattern (wirings L11 to L16) is formed on the substrate 10a by printing using an inkjet printer, and in step S20, eight magnetoresistance effect elements 21a to 28a are mounted on the substrate 10a with their pin directions changed so as to form a first bridge circuit C1 and a second bridge circuit C2, thereby manufacturing the magnetic sensor 100a.

[0128] In the magnetic sensor 100a configured as described above, the magnetoresistive element is mounted on the substrate 10a after the wiring pattern is formed, so that the magnetization direction of the magnetization fixed layer of the magnetoresistive element can be adjusted as desired by adjusting the mounting orientation of the magnetoresistive element. Furthermore, since the wiring pattern is formed by printing, it can be manufactured more easily than when the wiring pattern is formed by photolithography or the like.

[0129] (Other embodiments) The manufacturing methods of magnetic sensors according to one or more aspects have been described above based on the embodiments, but the present disclosure is not limited to these embodiments. As long as they do not deviate from the spirit of the present disclosure, various modifications that a person skilled in the art can make to the present embodiments and embodiments constructed by combining components of different embodiments may also be included in the present disclosure.

[0130] For example, although the magnetic sensors according to the above-described embodiments and the like have been described as having a bridge circuit, the present disclosure is not limited thereto and may not have a bridge circuit. The magnetic sensor of the present disclosure may be any magnetic sensor that includes at least one magnetoresistive effect element. Furthermore, the magnetic sensor may have a circuit configuration other than a bridge circuit.

[0131] In addition, for example, in the above-described embodiment, an example in which a plurality of magnetoresistive effect elements are fabricated by cutting a laminate has been described, but the present invention is not limited to this, and for example, a plurality of magnetoresistive effect elements may be fabricated individually. In this case, cutting is not performed.

[0132] Furthermore, the order of the steps in the magnetic sensor manufacturing method described in the above embodiments and the like may be interchanged. Furthermore, the steps in the magnetic sensor manufacturing method described in the above embodiments and the like may be performed in a single process or in separate processes. Note that "performed in a single process" is intended to include the cases where each process is performed using a single device, where each process is performed consecutively, or where each process is performed at the same location. Furthermore, "separate processes" is intended to include the cases where each process is performed using a separate device, where each process is performed at a different time (e.g., on a different day), or where each process is performed at a different location. [Industrial Applicability]

[0133] The present disclosure is useful for magnetic sensors and the like having magnetoresistive effect elements. [Explanation of symbols]

[0134] 10, 10a Substrate (first substrate) 21, 22, 23, 24 Magnetoresistive effect element 21a, 22a, 23a, 24a: magnetoresistive element (first magnetoresistive element) 25a, 26a, 27a, 28a: magnetoresistive element (second magnetoresistive element) 31 Polyimide substrate 32 Magnetization fixed layer 33, 233 Nonmagnetic layer 34 Magnetization free layer 100, 100a magnetic sensor 230 Laminate 231 Polyimide substrate (second substrate) 232 Ferromagnetic layer (first ferromagnetic layer) 234 Ferromagnetic layer (second ferromagnetic layer) 300 Cutting Machine C1 First bridge circuit C2 Second bridge circuit L1, L2, L3, L4, L11, L12, L13, L14, L15, L16 wiring

Claims

1. a first step of forming a wiring pattern on a first substrate by printing; and a second step of mounting a magnetoresistive element having a magnetization fixed layer whose magnetization direction is fixed and a magnetization free layer whose magnetization direction changes in response to a magnetic field on the first substrate on which the wiring pattern is formed. A method for manufacturing a magnetic sensor.

2. In the second step, the plurality of magnetoresistive effect elements are mounted on the first substrate such that the magnetization direction of the magnetization fixed layer of at least one of the plurality of magnetoresistive effect elements is different from the magnetization direction of the magnetization fixed layer of at least one other of the plurality of magnetoresistive effect elements. The method for manufacturing the magnetic sensor according to claim 1 .

3. the plurality of magnetoresistive effect elements include four of the magnetoresistive effect elements, In the second step, a bridge circuit having four of the magnetoresistive effect elements is formed. The method for manufacturing the magnetic sensor according to claim 2 .

4. In the second step, four magnetoresistive elements are mounted on the first substrate so that the magnetization directions of the magnetoresistive elements positioned opposite each other in the bridge circuit are the same. The method for manufacturing the magnetic sensor according to claim 3 .

5. the plurality of magnetoresistive effect elements include four first magnetoresistive effect elements and four second magnetoresistive effect elements; In the second step, a first bridge circuit having the four first magnetoresistance effect elements and a second bridge circuit having the four second magnetoresistance effect elements are formed, the second bridge circuit being connected to a common power supply with the first bridge circuit; The magnetization direction of the magnetization fixed layer of the four first magnetoresistance effect elements constituting the first bridge circuit intersects with the magnetization direction of the magnetization fixed layer of the four second magnetoresistance effect elements constituting the second bridge circuit. The method for manufacturing the magnetic sensor according to claim 2 .

6. The method further includes a third step of cutting a laminate in which the magnetization fixed layer, the non-magnetic layer, and the magnetization free layer are laminated on the second substrate, thereby fabricating the magnetoresistive effect element. The method for manufacturing the magnetic sensor according to any one of claims 1 to 5.

7. The second substrate is flexible. The method for manufacturing the magnetic sensor according to claim 6 .

8. The third step further comprises: a first ferromagnetic layer, a non-magnetic layer, and a second ferromagnetic layer are stacked on the second substrate; The magnetization direction of the second ferromagnetic layer is fixed by performing a heat treatment on the second substrate in a magnetic field, thereby forming the laminate. The method for manufacturing the magnetic sensor according to claim 6 .

9. In the first step, the wiring pattern is formed by inkjet printing. The method for manufacturing the magnetic sensor according to any one of claims 1 to 5.

10. The first substrate is flexible. The method for manufacturing the magnetic sensor according to any one of claims 1 to 5.

11. In the second step, a plurality of the magnetoresistive effect elements are mounted on the same plane. The method for manufacturing the magnetic sensor according to any one of claims 1 to 5.

12. a substrate having a wiring pattern formed by printing; a plurality of magnetoresistive effect elements each having a magnetization fixed layer whose magnetization direction is fixed and a magnetization free layer whose magnetization direction changes in response to a magnetic field; The plurality of magnetoresistive effect elements are arranged on the substrate such that the magnetization direction of the magnetization fixed layer of at least one of the plurality of magnetoresistive effect elements is different from the magnetization direction of the magnetization fixed layer of at least one other of the plurality of magnetoresistive effect elements. Magnetic sensor.

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