Magnetic sensor and manufacturing method thereof

Abstract

The invention relates to a magnetic sensor and a manufacturing method thereof. The magnetic sensor (1) has at least one magnetic field detection element (2) and at least one first soft magnetic layer (3). The at least one magnetic field detection element (2) has a first magnetization-fixed layer (63), a magnetization-free layer (61) whose magnetization direction varies with respect to an external magnetic field, and a first non-magnetic layer (62). The first fixed magnetization layer (63), the free magnetization layer (61), and the first non-magnetic layer (62) are arranged in a first direction in the order of the free magnetization layer (61), the first non-magnetic layer (62), and the first fixed magnetization layer (63), and the magnetization direction of the first fixed magnetization layer (63) is fixed to the first direction. The at least one first soft magnetic layer (3) faces the at least one magnetic field detection element (2) in a first direction.

Description

Technical Field

[0001] This disclosure relates to a magnetic sensor and a method for manufacturing the same. Background Technology

[0002] Magnetic sensors utilizing the magnetoresistive effect typically have a free magnetized layer whose magnetization direction varies relative to an external magnetic field, a fixed magnetized layer whose magnetization direction is fixed, and a non-magnetic layer located between the free magnetized layer and the fixed magnetized layer. Japanese Patent Application Publication No. 2018-6598 discloses a magnetic sensor in which the magnetization direction of the fixed magnetized layer is fixed as the stacking direction of the free magnetized layer, the non-magnetic layer, and the fixed magnetized layer. Summary of the Invention

[0003] The purpose of this disclosure is to provide a magnetic sensor in which the magnetization direction of the magnetization fixed layer is fixed as the stacking direction of the magnetization free layer, the non-magnetic layer and the magnetization fixed layer, and the magnetization direction of the magnetization fixed layer is not easily tilted from the stacking direction.

[0004] The magnetic sensor disclosed herein has at least one magnetic field detection element and at least one first soft magnetic layer. The at least one magnetic field detection element has a first magnetized fixed layer, a magnetized free layer whose magnetization direction varies with an external magnetic field, and a first non-magnetic layer. The first magnetized fixed layer, the magnetized free layer, and the first non-magnetic layer are arranged in the order of magnetized free layer, first non-magnetic layer, and first magnetized fixed layer in a first direction, and the magnetization direction of the first magnetized fixed layer is fixed to the first direction. The at least one first soft magnetic layer is opposite to the at least one magnetic field detection element in the first direction. Attached Figure Description

[0005] Figures 1A-1B This is a schematic structural diagram of the magnetic sensor according to the first embodiment.

[0006] Figure 2 This is a schematic structural diagram of the magnetic sensor according to the second embodiment.

[0007] Figure 3 This is a schematic structural diagram of the magnetic sensor according to the third embodiment.

[0008] Figure 4 This is a schematic structural diagram of the magnetic sensor according to the fourth embodiment.

[0009] Figure 5 This is a schematic structural diagram of the magnetic sensor according to the fifth embodiment.

[0010] Figures 6A-6C This is a schematic structural diagram of the magnetic sensor according to the sixth embodiment and comparative example.

[0011] Figure 7 This is a schematic structural diagram of the magnetic sensor according to the seventh embodiment.

[0012] Figure 8 This is a schematic structural diagram of the magnetic sensor according to the eighth embodiment.

[0013] Figure 9 This is a schematic structural diagram of the magnetic sensor according to the ninth embodiment.

[0014] Explanation of reference numerals in the attached figures:

[0015] 1…Magnetic sensor

[0016] 2…Magnetic field detection element

[0017] 3…First soft magnetic layer

[0018] 4…Second soft magnetic layer

[0019] 5… Upper electrode layer

[0020] 6…Layered bodies

[0021] 7…Lower electrode layer

[0022] 11~14…First to fourth element units

[0023] 61…Magnetized Free Layer

[0024] 62…First non-magnetic layer

[0025] 63…First magnetization fixation layer

[0026] 64…Intermediate layer

[0027] 65…Second magnetization fixing layer

[0028] 66…Second non-magnetic layer

[0029] 67…Antiferromagnetic layer Detailed Implementation

[0030] In the magnetic sensor described in Japanese Patent Application Publication No. 2018-6598, although the magnetization direction of the magnetization fixing layer is fixed to the stacking direction, the magnetization direction of the magnetization fixing layer may be tilted from the stacking direction due to an external magnetic field orthogonal to the stacking direction. This tilting of the magnetization direction of the magnetization fixing layer may cause a decrease in the output of the magnetic sensor.

[0031] Hereinafter, some embodiments of the present disclosure will be described with reference to the accompanying drawings. In the following description and drawings, the direction in which the multiple layers of the laminate 6 are stacked (the first direction) is referred to as the Z direction. The direction from the laminate 6 toward the upper electrode layer 5 is referred to as the +Z direction. The direction from the laminate 6 toward the lower electrode layer 7 or the substrate is referred to as the -Z direction. The direction orthogonal to the Z direction is referred to as the X direction. For convenience, the X direction is marked in the drawings, but the X direction can be any direction orthogonal to the Z direction. Unless otherwise stated, the hollow arrows in the drawings indicate the magnetization directions of the first magnetized fixed layer 63 and the second magnetized fixed layer 65. The thick lines with arrows indicate the magnetization direction of the magnetized free layer 61 in the state of no external magnetic field (hereinafter referred to as the "zero magnetic field state"). The dashed lines with arrows conceptually represent magnetic flux (external magnetic field).

[0032] First Implementation Method

[0033] Figures 1A-1B This shows a schematic structure of the magnetic sensor 1 according to the first embodiment. Figure 1A This is the front view of magnetic sensor 1. Figure 1B This is a top view of the magnetic sensor 1 viewed from the Z-direction. The magnetic sensor 1 has a magnetic field detection element 2, and a first soft magnetic layer 3 and a second soft magnetic layer 4 that hold the magnetic field detection element 2 in the Z-direction. The magnetic field detection element 2 has a silicon substrate (not shown), a laminate 6, and upper and lower electrode layers 5 and 7 that supply sensing current to the laminate 6. The upper electrode layer 5, the laminate 6, and the lower electrode layer 7 are arranged on the substrate in the Z-direction in the order of upper electrode layer 5, laminate 6, and lower electrode layer 7. Although not shown, other layers are provided between the lower electrode layer 7 and the substrate, and the lower electrode layer 7 is separated from the substrate. The upper electrode layer 5 and the lower electrode layer 7 can be formed by a laminate film made of conductors such as Ta, Cu, and Ru. The first soft magnetic layer 3 and the second soft magnetic layer can be formed of materials such as NiFe.

[0034] The laminate 6 has a magnetized free layer 61, a first non-magnetic layer 62, a first magnetized fixed layer 63, a second magnetized fixed layer 65, and an intermediate layer 64. These layers are arranged in the -Z direction from the upper electrode layer 5 toward the lower electrode layer 7 in the order of magnetized free layer 61, first non-magnetic layer 62, first magnetized fixed layer 63, intermediate layer 64, and second magnetized fixed layer 65, with adjacent layers touching each other. These layers can also be stacked in reverse. Specifically, they can also be arranged in the -Z direction from the upper electrode layer 5 toward the lower electrode layer 7 in the order of second magnetized fixed layer 65, intermediate layer 64, first magnetized fixed layer 63, first non-magnetic layer 62, and magnetized free layer 61.

[0035] The magnetized free layer 61 is a magnetic layer whose magnetization direction varies relative to an external magnetic field. The magnetized free layer 61 can be formed from ferromagnetic materials such as Ni, Fe, or Co, alloys composed of two or more of these elements, or alloys in which B or Si is added and made amorphous. In a zero magnetic field state, the magnetization direction of the magnetized free layer 61 is orthogonal to the Z-direction.

[0036] The first non-magnetic layer 62 is composed of an insulating layer such as MgO or Al2O3. In this embodiment, the magnetic field detection element 2 operates as a tunneling magnetoresistance (TMR) element. The first non-magnetic layer 62 can also be composed of a non-magnetic metal layer such as copper or silver. In this case, the magnetic field detection element 2 operates as a giant magnetoresistance (GMR) element. Compared to a GMR element, a TMR element can more easily achieve a higher output.

[0037] The first magnetization fixing layer 63 is a magnetic layer whose magnetization direction is fixed in the Z direction. The first magnetization fixing layer 63 is magnetically coupled to the second magnetization fixing layer 65 through the synthetic antiferromagnetic coupling via the intermediate layer 64. The magnetization direction of the first magnetization fixing layer 63 is fixed in the opposite direction to the magnetization direction of the second magnetization fixing layer 65. The first magnetization fixing layer 63 and the second magnetization fixing layer 65 can be formed from a multilayer film of Co and Pt films, or from a multilayer film of Co and Pd films, a multilayer film of Co and Ni films, or other materials with strong perpendicular magnetic anisotropy. The intermediate layer 64 is composed of a nonmagnetic metal such as ruthenium that produces RKKY (Ruderman-Kittel-Kasuya-Yosida) coupling. The multilayer film composed of the first magnetization fixing layer 63, the intermediate layer 64, and the second magnetization fixing layer 65 is also called a SAF (Synthetic Antiferromagnetic) structure. Because the magnetization directions of the first magnetization fixing layer 63 and the second magnetization fixing layer 65 are opposite to each other, the leakage magnetic field applied from the first magnetization fixing layer 63 to the magnetization free layer 61 can be suppressed. The magnetization amount of the first magnetization fixing layer 63 and the magnetization amount of the second magnetization fixing layer 65 can be set to the same level. Figure 1A In this configuration, the first magnetized fixing layer 63 is magnetized in the +Z direction, and the second magnetized fixing layer 65 is magnetized in the -Z direction. However, it is also possible that the first magnetized fixing layer 63 is magnetized in the -Z direction, and the second magnetized fixing layer 65 is magnetized in the +Z direction.

[0038] If an external magnetic field with a Z-direction component is applied to the magnetized free layer 61, the magnetization direction of the magnetized free layer 61 tilts towards the Z-direction. Consequently, the angle between the magnetization direction of the magnetized free layer 61 and the magnetization direction of the first magnetized fixed layer 63 changes, and due to the magnetoresistance effect, the resistance of the laminate 6 changes. By detecting the change in the resistance of the laminate 6, the strength of the Z-direction component of the external magnetic field can be measured. Therefore, the magnetic sensor 1 of this embodiment detects the magnetic field in the Z-direction.

[0039] The first soft magnetic layer 3 and the second soft magnetic layer 4 are opposite to the magnetic field detection element 2 (or the laminate 6) in the Z direction. The magnetic field detection element 2 (or the laminate 6) is located between the first soft magnetic layer 3 and the second soft magnetic layer 4 in the Z direction. Either the first soft magnetic layer 3 or the second soft magnetic layer 4 may be omitted. The first soft magnetic layer 3 and the second soft magnetic layer 4 attenuate the external magnetic field applied to the laminate 6 in the X direction by absorbing magnetic flux in the X direction. The magnetization direction of the first magnetization fixed layer 63 is fixed in the Z direction. If a stronger magnetic field is applied to the first magnetization fixed layer 63 from a direction other than the Z direction, the magnetization direction of the first magnetization fixed layer 63 will tilt from the Z direction, thereby potentially reducing the output of the magnetic sensor 1. In addition, the magnetization direction of the magnetization free layer 61 is determined by the combined magnetic field of the magnetic field other than the Z direction and the magnetic field in the Z direction. Therefore, if the intensity of the magnetic field applied from directions other than the Z direction fluctuates greatly, even if the magnetic field intensity in the Z direction is the same, the tilt of the magnetization direction of the magnetized free layer 61 relative to the Z direction will change, and the sensitivity of the magnetic sensor 1 may fluctuate. In this embodiment, since the first soft magnetic layer 3 and the second soft magnetic layer 4 act as shielding elements relative to the magnetic field applied from directions other than the Z direction, the above-mentioned possibility can be reduced.

[0040] like Figure 1B As shown, the stack 6 containing the magnetized free layer 61 has an elliptical shape with a major axis C1 on any cross section orthogonal to the Z direction. The shape of the stack 6 is unrestricted as long as it has a major axis C1; it can take any shape, such as a rectangle, a rectangle with semicircles connecting its two short sides, or a rectangle with rounded or chamfered corners. Due to the presence of the major axis C1, an anisotropic magnetic field parallel to the major axis C1 is generated in the magnetized free layer 61. This magnetic field functions as a bias magnetic field relative to the magnetized free layer 61. The bias magnetic field is a magnetic field that, in a zero magnetic field state, directs the magnetization direction of the magnetized free layer 61 toward a predetermined direction, with constant direction and intensity. In a zero magnetic field state, the magnetized free layer 61 is magnetized by the bias magnetic field to a direction parallel to the major axis C1. Because the generation of a large number of magnetic domains in the magnetized free layer 61 is suppressed, the output of the magnetic field relative to the Z direction easily becomes stable.

[0041] On the other hand, if an external magnetic field is applied in the same direction as the bias magnetic field, the magnetization direction of the magnetized free layer 61 is difficult to tilt towards the Z direction, resulting in decreased sensitivity relative to the Z-direction magnetic field. If an external magnetic field is applied in the opposite direction to the bias magnetic field, the magnetization direction of the magnetized free layer 61 easily tilts towards the Z direction, increasing sensitivity relative to the Z-direction magnetic field. As a result, the output signal tends to become unstable relative to the direction of the external magnetic field. Therefore, it is preferable to suppress the application of external magnetic fields in the same or opposite direction to the bias magnetic field to the magnetized free layer 61 as much as possible. Furthermore, the external magnetic field referred to herein is an external magnetic field other than the object being detected, and its direction or intensity can generally change over time. The external magnetic field is a magnetic field other than the Z-direction and does not include the bias magnetic field.

[0042] Typically, the shielding function of a magnetic material is generated by magnetizing it with an external magnetic field. That is, if an external magnetic field is applied, magnetic poles are generated at the ends of the magnetic material in the direction of application of the external magnetic field. A portion of the magnetic field generated by these poles then counteracts the external magnetic field, thus shielding the area around the magnetic material from external magnetic fields. Along the long axis (easy magnetization axis) of the magnetic material, a relatively weak external magnetic field generates magnetic poles, resulting in strong shielding (counteracting the external magnetic field). Conversely, along the short axis (difficult magnetization axis) of the magnetic material, it is difficult to magnetize it and generate magnetic poles, therefore, the shielding is weaker.

[0043] In this embodiment, at least one of the first soft magnetic layer 3 and the second soft magnetic layer 4 has a major axis C2. The direction of the bias magnetic field applied to the magnetized free layer 61 can be set to be parallel to the major axis C2 of at least one of the first soft magnetic layer 3 and the second soft magnetic layer 4. In other words, the magnetized free layer 61 has a major axis C1, and at least one of the first soft magnetic layer 3 and the second soft magnetic layer 4 has a major axis C2; the major axes C1 and C2 can be set to be parallel. Alternatively, both the first soft magnetic layer 3 and the second soft magnetic layer 4 have major axes C2 in the same direction, and the direction of the bias magnetic field applied to the magnetized free layer 61 can be set to be parallel to the major axis C2 of the first soft magnetic layer 3 and the second soft magnetic layer 4. In other words, the magnetized free layer 61 has a major axis C1, and both the first soft magnetic layer 3 and the second soft magnetic layer 4 have major axes C2 in the same direction, allowing the major axes C1 and C2 to be parallel. Furthermore, the shapes of the first soft magnetic layer 3 and the second soft magnetic layer 4 are not limited as long as they have a major axis C2. They can take any shape, such as a rectangle, a rectangle with semicircles connected to the short sides on both sides, or a rectangle with rounded or chamfered corners.

[0044] The bias magnetic field application unit is not limited to the shape of the magnetized free layer 61 itself; it can also be a magnet disposed on the side of the magnetized free layer 61 or a magnet disposed outside the magnetic sensor 1. Alternatively, the bias magnetic field application unit can be omitted. In this case, the magnetized free layer 61 can be made into a shape that does not have a major axis when viewed from the Z direction (circle, square, etc.), and the magnetization direction can be inconsistent in the zero magnetic field state. The first soft magnetic layer 3 and the second soft magnetic layer 4 can also be made into a shape that does not have a major axis when viewed from the Z direction (circle, square, etc.).

[0045] The first soft magnetic layer 3 and the second soft magnetic layer 4 also enhance the magnetic field in the Z direction. Magnetic flux flows around the first soft magnetic layer 3 (or the second soft magnetic layer 4) towards the first soft magnetic layer 3 (or the second soft magnetic layer 4) and is emitted from the second soft magnetic layer 4 (or the first soft magnetic layer 3) to the surrounding area. The first soft magnetic layer 3 and the second soft magnetic layer 4 have a magnetic focusing effect relative to the magnetic field in the Z direction and function as a magnetic yoke, thus improving the output of the magnetic sensor 1. Therefore, in this embodiment, the first soft magnetic layer 3 and the second soft magnetic layer 4 function as both a shield and a magnetic yoke, depending on the direction of the magnetic field. For example, in magnetoresistive memory (MRAM), protecting the recorded data is important; therefore, regardless of the direction of the magnetic field, the soft magnetic material disposed around the memory section functions as a shield. The magnetic sensor 1 of this embodiment differs significantly in the function of its soft magnetic layers (first soft magnetic layer 3 and second soft magnetic layer 4) compared to other applications using the magnetoresistive effect.

[0046] Furthermore, in cases where a magnetic sensor using a technique where the magnetization direction of the magnetized free layer varies along the in-plane direction (X direction) detects the magnetic field in the Z direction together with a magnetic yoke, the magnetic field in the Z direction needs to be bent to the in-plane direction by the magnetic yoke and applied to the magnetized free layer. Therefore, when viewed from the Z direction, the laminate is offset relative to the magnetic yoke. In this embodiment, since the orientation of the magnetic field in the Z direction is not changed when it is detected, the first soft magnetic layer 3 and the second soft magnetic layer 4 can be positioned directly above or below the laminate 6 in the Z direction. That is, when viewed from the Z direction, the center of the magnetized free layer 61 can overlap with the first soft magnetic layer 3 and the second soft magnetic layer 4, thus facilitating the compaction of the magnetic sensor 1.

[0047] Second Implementation Method

[0048] Figure 2The diagram shows a schematic structure of the magnetic sensor 1 according to the second embodiment. The structure and effects, which are omitted from the description, are the same as in the first embodiment. The laminate 6 has a magnetized free layer 61, a first non-magnetic layer 62, a first magnetized fixed layer 63, a second magnetized fixed layer 65, and a second non-magnetic layer 66. These layers are arranged in the -Z direction from the upper electrode layer 5 toward the lower electrode layer 7 in the order of the second magnetized fixed layer 65, the second non-magnetic layer 66, the magnetized free layer 61, the first non-magnetic layer 62, and the first magnetized fixed layer 63, with adjacent layers touching each other. These layers can also be stacked in the opposite direction. Specifically, they can also be arranged in the -Z direction from the upper electrode layer 5 toward the lower electrode layer 7 in the order of the first magnetized fixed layer 63, the first non-magnetic layer 62, the magnetized free layer 61, the second non-magnetic layer 66, and the second magnetized fixed layer 65. The magnetized free layer 61, the first non-magnetic layer 62, the first magnetized fixed layer 63, and the second magnetized fixed layer 65 can be configured in the same way as in the first embodiment. The second non-magnetic layer 66 is provided to magnetically separate the magnetized free layer 61 and the second magnetized fixed layer 65. Therefore, as long as it is a non-magnetic layer, it is not limited and can be formed from any of the following: metals such as copper, insulators such as Al2O3.

[0049] The magnetization direction of the second magnetization fixed layer 65 is fixed to be opposite to that of the first magnetization fixed layer 63. Therefore, in this embodiment, leakage magnetic field applied to the magnetization free layer 61 can also be suppressed. Figure 2 In this configuration, the first magnetized fixing layer 63 is magnetized in the +Z direction, and the second magnetized fixing layer 65 is magnetized in the -Z direction. However, it is also possible for the first magnetized fixing layer 63 to be magnetized in the -Z direction and the second magnetized fixing layer 65 to be magnetized in the +Z direction. To make the magnetization directions of the first magnetized fixing layer 63 and the second magnetized fixing layer 65 opposite to each other, the anisotropic magnetic field Hk1 of the first magnetized fixing layer 63 and the anisotropic magnetic field Hk2 of the second magnetized fixing layer 65 can be different. For example, when Hk1 > Hk2, firstly, a magnetic field H1 in the Z direction that is larger than Hk1 is applied to the first magnetized fixing layer 63 and the second magnetized fixing layer 65. Since H1 > Hk1 > Hk2, the first magnetized fixing layer 63 and the second magnetized fixing layer 65 are magnetized in the same direction. Next, a magnetic field H2 with Hk1 > H2 > Hk2 and opposite to H1 is applied to the first magnetized fixing layer 63 and the second magnetized fixing layer 65. The magnetization direction of the first magnetization fixing layer 63 remains unchanged, while the magnetization direction of the second magnetization fixing layer 65 is reversed.

[0050] Third Implementation Method

[0051] Figure 3The diagram shows a schematic structure of the magnetic sensor 1 according to the third embodiment. The structure and effects, which are omitted from the description, are the same as in the first embodiment. The laminate 6 has a magnetized free layer 61, a first non-magnetic layer 62, a first magnetized fixed layer 63, and an antiferromagnetic layer 67. These layers are arranged in the -Z direction from the upper electrode layer 5 toward the lower electrode layer 7 in the order of magnetized free layer 61, first non-magnetic layer 62, first magnetized fixed layer 63, and antiferromagnetic layer 67, with adjacent layers touching each other. These layers can also be stacked in the opposite direction. Specifically, they can also be arranged in the -Z direction from the upper electrode layer 5 toward the lower electrode layer 7 in the order of antiferromagnetic layer 67, first magnetized fixed layer 63, first non-magnetic layer 62, and magnetized free layer 61. The magnetized free layer 61, first non-magnetic layer 62, and first magnetized fixed layer 63 can be configured in the same way as in the first embodiment. The antiferromagnetic layer 67 can be formed from IrMn, or it can also be formed from antiferromagnetic materials such as PtMn and FeRh.

[0052] The magnetization of the first magnetization fixing layer 63 can be achieved by applying an external magnetic field while annealing (heating). The first magnetization fixing layer 63 is exchange-coupled with the antiferromagnetic layer 67 and fixed in the same direction as the magnetization direction during annealing. If a strong Z-direction magnetic field is applied in the opposite direction to the magnetization direction of the first magnetization fixing layer 63, the magnetization direction of the first magnetization fixing layer 63 may temporarily reverse. If the magnetization direction of the first magnetization fixing layer 63 remains reversed, the output tilt may reverse (e.g., the output curve pointing to the upper right becomes the output curve pointing to the lower right). However, if the magnetic field state is zero, the magnetization direction of the first magnetization fixing layer 63 returns to its original direction. Therefore, the magnetization direction of the first magnetization fixing layer 63 in the zero magnetic field state is easily stabilized and output reversal is not likely to occur. Figure 3 In this process, the antiferromagnetic layer 67 and the first magnetization fixing layer 63 are magnetized in the +Z direction, but they can also be magnetized in the -Z direction.

[0053] Fourth Implementation Method

[0054] Figure 4This diagram shows a schematic structure of the magnetic sensor 1 according to the fourth embodiment. The structure and effects described are the same as in the first embodiment, but are omitted from the description. The laminate 6 of this embodiment has a structure combining the first and third embodiments. The laminate 6 includes a magnetized free layer 61, a first non-magnetic layer 62, a first magnetized fixed layer 63, an intermediate layer 64 made of a non-magnetic metal such as ruthenium that generates RKKY coupling, a second magnetized fixed layer 65, and an antiferromagnetic layer 67. These layers are arranged in the Z-direction from the upper electrode layer 5 toward the lower electrode layer 7 in the order of magnetized free layer 61, first non-magnetic layer 62, first magnetized fixed layer 63, intermediate layer 64, second magnetized fixed layer 65, and antiferromagnetic layer 67, with adjacent layers touching each other. These layers can also be stacked in the opposite direction. Specifically, the layers can also be arranged in the following order from the upper electrode layer 5 toward the lower electrode layer 7 in the -Z direction: antiferromagnetic layer 67, second magnetized fixed layer 65, intermediate layer 64, first magnetized fixed layer 63, first nonmagnetic layer 62, and magnetized free layer 61.

[0055] With the SAF structure, the magnetization direction of the first magnetization fixing layer 63 is fixed in the opposite direction to that of the second magnetization fixing layer 65. Furthermore, the magnetization direction of the second magnetization fixing layer 65 is fixed in the same direction as the magnetization direction during annealing through exchange coupling with the antiferromagnetic layer 67. This embodiment combines the effects of both the first and third embodiments. Specifically, with the SAF structure, leakage magnetic fields applied to the magnetized free layer 61 can be suppressed, and the magnetization direction of the second magnetization fixing layer 65 in the zero magnetic field state is stabilized by the antiferromagnetic layer 67.

[0056] Fifth Implementation Method

[0057] Figure 5This diagram shows a schematic structure of the magnetic sensor 1 according to the fifth embodiment. The structure and effects described are the same as in the first embodiment. The structure of the laminate 6 in this embodiment is the same as in the first embodiment, but in the zero magnetic field state, the magnetization direction of the magnetized free layer 61 forms a vortex shape in a plane orthogonal to the Z direction. The magnetization state adopted by the magnetized free layer 61 in the zero magnetic field state is determined by the balance between the exchange energy and the static magnetic energy of the magnetized free layer 61. Generally, a large saturation magnetization easily produces a vortex shape. In the zero magnetic field state, the center of the vortex, called the magnetic core, is located at the center of the magnetized free layer 61, and the magnetization direction presents concentric circles centered on the magnetic core. If an external magnetic field in the Z direction is applied, the magnetization direction tilts entirely towards the Z direction, thus obtaining the same magnetoresistance effect as in the first embodiment. In this embodiment, the magnetized free layer 61 forms a vortex shape in the zero magnetic field state, therefore, when subjected to a magnetic field other than the Z direction, fluctuations in sensitivity are easily suppressed. This embodiment can also be combined with the second to fourth embodiments. Specifically, the magnetization direction of the magnetized free layer 61 in the second to fourth embodiments can be set to a vortex shape.

[0058] Sixth Implementation Method

[0059] Figure 6A This diagram shows a schematic structure of the magnetic sensor 1 according to the sixth embodiment. The structure and effects described are the same as in the first embodiment. The magnetic sensor 1 of this embodiment has multiple magnetic field detection elements 2 as in the fifth embodiment; that is, magnetic field detection elements 2 whose magnetization direction forms a vortex shape in a zero magnetic field state. The structure of each of the multiple magnetic field detection elements 2 can be the same as that of the magnetic field detection element 2 in the fifth embodiment. The multiple magnetic field detection elements 2 are connected in series. The number of multiple magnetic field detection elements 2 is not limited, but... Figure 6A For convenience, two magnetic field detection elements 2 (hereinafter referred to as the first magnetic field detection element 2A and the second magnetic field detection element 2B) are shown. Multiple magnetic field detection elements 2 are positioned opposite a first soft magnetic layer 3 in the Z direction. Hollow arrows indicate the magnetization direction of the magnetic core in the zero magnetic field state of the magnetized free layer 61.

[0060] Figure 6B The schematic structure of the magnetic sensor 101 of the comparative example is shown. Figure 6C This represents the magnetization curve of the magnetized free layer 61. The magnetization direction of the core of the magnetized free layer 61 can be either +Z or -Z in the zero magnetic field state. The magnetization curve of the magnetized free layer 61 (with the horizontal axis representing magnetic field strength and the vertical axis representing magnetization) shifts left and right depending on the direction of the core. For example, when the magnetization direction of the core is +Z, the magnetization curve shifts to the left; when the magnetization direction of the core is -Z, the magnetization curve shifts to the right. This magnetic characteristic reduces the accuracy of the output of the magnetic sensor 1.

[0061] In this embodiment, the magnetization directions of the magnetic cores in the first magnetic field detection element 2A and the second magnetic field detection element 2B (a portion and the remainder of the plurality of magnetic field detection elements 2) are opposite to each other. Therefore, the shifts in the magnetization curves of the magnetized free layer 61 of the first magnetic field detection element 2A and the magnetized free layer 61 of the second magnetic field detection element 2B are canceled out, and the accuracy of the output of the magnetic sensor 1 is improved. It can be understood that in Figure 6A In this configuration, the same number of magnetic field detection elements 2 can be arranged in the left and right regions of the first soft magnetic layer 3. More generally, the same number of magnetic field detection elements 2 can be arranged on both sides of the plane P of the first soft magnetic layer 3, which includes a center line C parallel to the Z direction.

[0062] To make the magnetization direction of the core of the first magnetic field detection element 2A opposite to the magnetization direction of the core of the second magnetic field detection element 2B, an external magnetic field can be applied along the X direction. The external magnetic field in the X direction is bent to the +Z direction through the first soft magnetic layer 3. A magnetic field containing a component in the +Z direction is applied to the first magnetic field detection element 2A. A magnetic field containing a component in the -Z direction is applied to the second magnetic field detection element 2B. If the Z component of the external magnetic field is large enough, the core will temporarily disappear. If the external magnetic field is removed, the core will reappear. The magnetization direction of the core is determined by the Z component of the last applied magnetic field. Figure 6A In the example shown, the magnetization direction of the core of the first magnetic field detection element 2A is towards the +Z direction, and the magnetization direction of the core of the second magnetic field detection element 2B is towards the -Z direction.

[0063] Plane P can be parallel to the Z direction or in any direction. By applying an external magnetic field from a direction orthogonal to plane P, a magnetic field containing a component in the +Z direction can be applied to a portion of the magnetic field detection elements 2, and a magnetic field containing a component in the -Z direction can be applied to the remaining magnetic field detection elements 2. Plane P can also be determined by the arrangement of multiple magnetic field detection elements 2. Specifically, plane P can be determined by dividing the multiple magnetic field detection elements 2 into two parts by plane P. Figures 6A-6B Only the first soft magnetic layer 3 is shown. However, when the first soft magnetic layer 3 and the second soft magnetic layer 4 are provided, the first magnetic field detection element 2A and the second magnetic field detection element 2B can be positioned at a position offset from the center of the first soft magnetic layer 3 and the second soft magnetic layer 4 in the Z direction. Therefore, a magnetic field containing a component in the +Z direction and a magnetic field containing a component in the -Z direction can be applied to the first magnetic field detection element 2A and the second magnetic field detection element 2B, respectively.

[0064] Seventh Implementation Method

[0065] Figure 7This diagram shows a schematic structure of the magnetic sensor 1 according to the seventh embodiment. The structure and effects described are the same as in the first embodiment. The laminate 6 has a magnetized free layer 61, a first non-magnetic layer 62, and a first magnetized fixed layer 63. These layers are arranged in the -Z direction from the upper electrode layer 5 toward the lower electrode layer 7 in the order of magnetized free layer 61, first non-magnetic layer 62, and first magnetized fixed layer 63, with adjacent layers touching each other. These layers can also be stacked in the opposite direction. Specifically, they can also be arranged in the -Z direction from the upper electrode layer 5 toward the lower electrode layer 7 in the order of first magnetized fixed layer 63, first non-magnetic layer 62, and magnetized free layer 61. This embodiment omits the second magnetized fixed layer 65 and the second non-magnetic layer 66 of the first embodiment; otherwise, the structure is the same as in the first embodiment. This embodiment simplifies the structure of the laminate 6, thereby reducing the cost of the magnetic sensor 1.

[0066] Eighth Implementation Method

[0067] Figure 8 This diagram illustrates the schematic structure of the magnetic sensor 1 according to the eighth embodiment. The magnetic sensor 1 of this embodiment is a half-bridge magnetic sensor that combines the magnetic field detection elements 2 of the various embodiments described above. The magnetic sensor 1 has first and second element units 11 and 12, each containing at least one magnetic field detection element 2. In one embodiment, the first and second element units 11 and 12 each contain an array of multiple magnetic field detection elements 2 connected in series. The first element unit 11 and the second element unit 12 form a group 15 connected in series. One end of the group 15 is connected to the power supply VDD, and the other end is grounded (GND). The magnetic sensor 1 has an output section 17 located between the first element unit 11 and the second element unit 12. The magnetization direction of the first magnetization fixing layer 63 of the first element unit 11 and the first magnetization fixing layer 63 of the second element unit 12 are opposite to each other. Although the first soft magnetic layer 3 (shown as a dashed line for convenience) and the second soft magnetic layer 4 cover the entire first and second element units 11 and 12 in the Z direction, they can cover the first element unit 11 and the second element unit 12 individually, or they can cover each magnetic field detection element 2 individually.

[0068] In the eighth embodiment, the magnetic sensor 1 (third and fourth embodiments) with an antiferromagnetic layer 67, comprising the magnetic field detection element 2, can be manufactured using laser annealing. Specifically, for example, in... Figure 3In the case of the membrane structure shown, the first element unit 11 is irradiated with a laser while a magnetic field (in the first direction) is applied along the Z direction, magnetizing the first magnetization fixing layer 63 of the first element unit 11. The magnetization direction is fixed through exchange coupling with the antiferromagnetic layer 67. Next, the second element unit 12 is irradiated with a laser while a magnetic field (in the second direction), for example, opposite to the magnetic field applied to the first element unit 11, is applied, magnetizing the first magnetization fixing layer 63 of the second element unit 12. The magnetization direction is fixed through exchange coupling with the antiferromagnetic layer 67. Figure 4 In the case of the film structure shown, the second magnetization fixing layer 65 is magnetized, and the magnetization direction is fixed by exchange coupling with the antiferromagnetic layer 67. During laser annealing, laser light is irradiated at multiple locations. Considering factors such as the forming accuracy of the element units, the interval between the laser irradiation locations is preferably about 5 μm or more, and more preferably about 10 μm or more.

[0069] Furthermore, although laser annealing is used to magnetize the magnetized fixing layer in this embodiment, the heating method is not limited to laser as long as the first element unit 11 and the second element unit 12 can be locally heated. For example, heating wiring can be provided near the first element unit 11 and the second element unit 12, and the heating wiring can be energized to heat up the heating wiring and heat the first element unit 11 and the second element unit 12.

[0070] Ninth Implementation Method

[0071] Figure 9This diagram illustrates a schematic structure of the magnetic sensor 1 according to the ninth embodiment. The magnetic sensor 1 of this embodiment is a full-bridge magnetic sensor that combines the magnetic field detection elements 2 of the various embodiments described above. The magnetic sensor 1 has first to fourth element units 11 to 14, each containing at least one magnetic field detection element 2. In one embodiment, the first to fourth element units 11 to 14 each contain an array of multiple magnetic field detection elements 2 connected in series. The first element unit 11 and the second element unit 12 form a first group 16A connected in series. The third element unit 13 and the fourth element unit 14 form a second group 16B connected in series. One end of the first group 16A and the second group 16B is connected to the power supply VDD, and the other end is grounded (GND). The first element unit 11 and the fourth element unit 14 are disposed on the power supply VDD side, and the second element unit 12 and the third element unit 13 are disposed on the ground side (GND). The magnetic sensor 1 has a differential unit 18 that calculates the difference between the outputs of the first element unit 11 and the second element unit 12, and between the outputs of the third element unit 13 and the fourth element unit 14. The magnetization directions of the first magnetization fixing layer 63 of the first element unit 11 and the third element unit 13 are the same. The magnetization directions of the first magnetization fixing layer 63 of the second element unit 12 and the fourth element unit 14 are opposite to those of the first magnetization fixing layer 63 of the first element unit 11 and the third element unit 13. Although the first soft magnetic layer 3 (shown as a dashed line for convenience) and the second soft magnetic layer 4 cover the entire first to fourth element units 11 to 14 in the Z direction, they can also cover the first to fourth element units 11 to 14 individually, or they can cover each magnetic field detection element 2 individually.

[0072] The voltage drop in each element unit 11-14 is approximately proportional to the resistance of element units 11-14. Therefore, if the resistances of the first to fourth element units 11-14 are set to R1-R4 respectively, the midpoint voltage V1 is V1 = R2 / (R1+R2)×VDD, and the midpoint voltage V2 is V2 = R3 / (R3+R4)×VDD. By using the differential converter 18 to calculate the difference V1-V2 between the midpoint voltages V1 and V2, twice the sensitivity is obtained compared to detecting the midpoint voltages V1 and V2. Furthermore, in the case of a shift in the midpoint voltages V1 and V2, the effect of the shift can be eliminated by detecting the difference.

[0073] In the magnetic sensor 1 of the ninth embodiment, the magnetic field detection element 2 includes an antiferromagnetic layer 67. The magnetic sensor 1 (third and fourth embodiments) can be manufactured using laser annealing. Specifically, for example, in... Figure 3In the case of the membrane structure shown, laser light is irradiated onto the first and third element units 11 and 13, and a magnetic field (in the first direction) is applied along the Z direction, magnetizing the first magnetization fixing layer 63 of the first and third element units 11 and 13. The magnetization direction is fixed through exchange coupling with the antiferromagnetic layer 67. Next, laser light is irradiated onto the second and fourth element units 12 and 14, and a magnetic field (in the second direction), for example, opposite in direction to the magnetic field applied to the first magnetization fixing layer 63 of the first and third element units 11 and 13, is applied, magnetizing the first magnetization fixing layer 63 of the second and fourth element units 12 and 14. The magnetization direction is fixed through exchange coupling with the antiferromagnetic layer 67. Figure 4 In the case of the film structure shown, the second magnetization fixing layer 65 is magnetized, and the magnetization direction is fixed by exchange coupling with the antiferromagnetic layer 67. In this embodiment, the heating method is not limited to laser. For details, please refer to the eighth embodiment. Furthermore, in this embodiment, the interval between the laser irradiation positions is preferably about 5 μm or more, and more preferably about 10 μm or more.

[0074] In the eighth and ninth embodiments, the SAF structure described above can also be used to make the magnetization direction of the first magnetization fixing layer 63 of some element units opposite to that of other element units. For example, in the case of using the magnetic field detection element 2 of the first embodiment in the eighth embodiment, the film thickness of the first magnetization fixing layer 63 in the first element unit 11 can be greater than that of the second magnetization fixing layer 65, and the film thickness of the first magnetization fixing layer 63 in the second element unit 12 can be less than that of the second magnetization fixing layer 65. However, in this structure, since the film structure, including the film thickness, is different in the first element unit 11 and the second element unit 12, the manufacturing process is complex and it is difficult to suppress the leakage magnetic field. By adopting the third and fourth embodiments using the antiferromagnetic layer 67, when forming a bridge, it is also possible to make all magnetic field detection elements 2 with the same film structure, including the film thickness.

[0075] According to this disclosure, a magnetic sensor is provided in which the magnetization direction of the magnetization fixed layer is fixed to the stacking direction of the magnetization free layer, the non-magnetic layer and the magnetization fixed layer, and the magnetization direction of the magnetization fixed layer is not easily tilted from the stacking direction.

Claims

1. A magnetic sensor, wherein, It has at least one magnetic field detection element and at least one first soft magnetic layer. The at least one magnetic field detection element has a first magnetized fixed layer, a magnetized free layer whose magnetization direction changes relative to the external magnetic field, and a first non-magnetic layer. The first magnetized fixed layer, the first magnetized free layer, and the first non-magnetic layer are arranged in the order of the first magnetized free layer, the first non-magnetic layer, and the first magnetized fixed layer in a first direction. The magnetization direction of the first magnetized fixed layer is fixed to the first direction. The at least one first soft magnetic layer is opposite to the at least one magnetic field detection element in the first direction.

2. The magnetic sensor according to claim 1, wherein, The magnetic sensor has at least one second soft magnetic layer opposite to the at least one magnetic field detection element in the first direction, and the at least one magnetic field detection element is located between the at least one first soft magnetic layer and the at least one second soft magnetic layer.

3. The magnetic sensor according to claim 2, wherein, The magnetized free layer has a long axis, and at least one of the first soft magnetic layer and the second soft magnetic layer has a long axis, the long axis of the magnetized free layer being parallel to the long axis of at least one of the first soft magnetic layer and the second soft magnetic layer.

4. The magnetic sensor according to any one of claims 1 to 3, wherein, The first non-magnetic layer is composed of an insulating layer.

5. The magnetic sensor according to any one of claims 1 to 3, wherein, The at least one magnetic field detection element has a second magnetized fixed layer and an intermediate layer made of non-magnetic metal. The first magnetized fixed layer, the magnetized free layer, the first non-magnetic layer, the second magnetized fixed layer, and the intermediate layer are arranged in the first direction in the order of the magnetized free layer, the first non-magnetic layer, the first magnetized fixed layer, the intermediate layer, and the second magnetized fixed layer. The magnetization direction of the second magnetization fixing layer is fixed to be opposite to the magnetization direction of the first magnetization fixing layer.

6. The magnetic sensor according to any one of claims 1 to 3, wherein, The at least one magnetic field detection element has a second magnetized fixed layer and a second non-magnetic layer, wherein the first magnetized fixed layer, the first magnetized free layer, the first non-magnetic layer, the second magnetized fixed layer, and the second non-magnetic layer are arranged in the first direction in the order of the second magnetized fixed layer, the second non-magnetic layer, the first magnetized free layer, the first non-magnetic layer, and the first magnetized fixed layer. The magnetization direction of the second magnetization fixing layer is fixed to be opposite to the magnetization direction of the first magnetization fixing layer.

7. The magnetic sensor according to any one of claims 1 to 3, wherein, The at least one magnetic field detection element has an antiferromagnetic layer, and the first magnetized fixed layer, the first magnetized free layer, the first non-magnetic layer, and the antiferromagnetic layer are arranged in the first direction in the order of the magnetized free layer, the first non-magnetic layer, the first magnetized fixed layer, and the antiferromagnetic layer. The magnetization direction of the first magnetization fixing layer is fixed by exchange coupling with the antiferromagnetic layer.

8. The magnetic sensor according to any one of claims 1 to 3, wherein, The at least one magnetic field detection element has an intermediate layer made of a non-magnetic metal, a second magnetized fixed layer, and an antiferromagnetic layer. The first magnetized fixed layer, the magnetized free layer, the first non-magnetic layer, the intermediate layer, the second magnetized fixed layer, and the antiferromagnetic layer are arranged in the first direction in the order of the magnetized free layer, the first non-magnetic layer, the first magnetized fixed layer, the intermediate layer, the second magnetized fixed layer, and the antiferromagnetic layer. The magnetization direction of the second magnetization fixing layer is fixed to the opposite direction to that of the first magnetization fixing layer through exchange coupling with the antiferromagnetic layer.

9. The magnetic sensor according to any one of claims 1 to 3, wherein, In the absence of the external magnetic field, the magnetization direction of the magnetized free layer is orthogonal to the first direction.

10. The magnetic sensor according to any one of claims 1 to 3, wherein, In the absence of the external magnetic field, the magnetization direction of the magnetized free layer forms a vortex shape in a plane orthogonal to the first direction.

11. The magnetic sensor according to claim 10, wherein, The at least one magnetic field detection element may be multiple magnetic field detection elements. In the absence of the external magnetic field, the magnetization direction of the magnetized free layer of each magnetic field detection element forms a vortex shape in a plane orthogonal to the first direction. The plurality of magnetic field detection elements are connected in series and are opposite to one of the first soft magnetic layers in the first direction. A portion and the remainder of the plurality of magnetic field detection elements are located on either side of a plane containing a center line parallel to the first direction in the first soft magnetic layer, and the magnetization directions at the center of the vortex shape are opposite to each other.

12. The magnetic sensor according to any one of claims 1 to 3, wherein, The at least one magnetic field detection element may be multiple magnetic field detection elements. The magnetic sensor has first and second element units, each comprising a portion of the plurality of magnetic field detection elements. The first component unit and the second component unit form a group connected in series, with one end of the group connected to a power supply and the other end grounded. The magnetic sensor has an output section located between the first element unit and the second element unit. The magnetization direction of the first magnetization fixing layer of the first element unit is opposite to that of the first magnetization fixing layer of the second element unit.

13. The magnetic sensor according to any one of claims 1 to 3, wherein, The at least one magnetic field detection element may be multiple magnetic field detection elements. The magnetic sensor has first to fourth element units, each comprising a portion of the plurality of magnetic field detection elements. The first and second component units form a first group connected in series, and the third and fourth component units form a second group connected in series. One end of the first and second groups is connected to a power supply, and the other end is grounded. The first component unit and the fourth component unit are disposed on the power supply side, and the second component unit and the third component unit are disposed on the ground side. The magnetic sensor has a differential converter that calculates the difference between the outputs of the first element unit and the second element unit, and between the outputs of the third element unit and the fourth element unit. The magnetization directions of the first magnetization fixing layer of the first element unit and the third element unit are the same, while the magnetization directions of the first magnetization fixing layer of the second element unit and the fourth element unit are opposite to the magnetization directions of the first magnetization fixing layer of the first element unit and the third element unit.

14. The magnetic sensor according to claim 12, wherein, The at least one first soft magnetic layer is a first soft magnetic layer, and the first soft magnetic layer is opposite to the first to fourth element units.

15. A method for manufacturing a magnetic sensor, wherein, have: The steps include fabricating a first component unit and a second component unit such that the first component unit and the second component unit form a group connected in series, with one end of the group connected to a power supply and the other end grounded; providing an output section between the first component unit and the second component unit; and providing at least one magnetic field detection element in each of the first component unit and the second component unit. The at least one magnetic field detection element provided in the first element unit and the second element unit has: The step of arranging the first magnetized fixed layer, the magnetized free layer whose magnetization direction changes relative to the external magnetic field, the first non-magnetic layer, and the antiferromagnetic layer in the order of the magnetized free layer, the first non-magnetic layer, the first magnetized fixed layer, and the antiferromagnetic layer in the first direction. The step of locally heating the first element unit while applying a magnetic field along the first direction to magnetize the first magnetization fixing layer of the first element unit; as well as The step of locally heating the second element unit while applying a magnetic field in a second direction opposite to the first direction to magnetize the first magnetization fixing layer of the second element unit.

16. The manufacturing method according to claim 15, wherein, The first element unit and the second element unit are locally heated by irradiation with a laser.

17. A method for manufacturing a magnetic sensor, wherein, have: The steps include fabricating first to fourth element units such that the first element unit and the second element unit form a first group connected in series, and the third element unit and the fourth element unit form a second group connected in series, with one end of the first group and the second group connected to a power supply and the other end grounded, the first element unit and the fourth element unit being disposed on the power supply side, and the second element unit and the third element unit being disposed on the grounding side, and providing at least one magnetic field detection element in each of the first to fourth element units; as well as The steps for constructing a differencer to calculate the difference between the outputs of the first and second element units, and between the outputs of the third and fourth element units. The at least one magnetic field detection element of the first to fourth element units has: The step of arranging the first magnetized fixed layer, the magnetized free layer whose magnetization direction changes relative to the external magnetic field, the first non-magnetic layer, and the antiferromagnetic layer in the order of the magnetized free layer, the first non-magnetic layer, the first magnetized fixed layer, and the antiferromagnetic layer in the first direction. The step of locally heating the first element unit and the third element unit while applying a magnetic field along the first direction to magnetize the first magnetization fixing layer of the first element unit and the third element unit; as well as The step of locally heating the second element unit and the fourth element unit while applying a magnetic field in a second direction opposite to the first direction, thereby magnetizing the first magnetization fixing layer of the second element unit and the fourth element unit.

18. The manufacturing method according to claim 17, wherein, The first to fourth element units are locally heated by irradiation with a laser.

Images