Magnetic sensor

Abstract

To provide a magnetic sensor which prevents a detection magnetic field range from decreasing even when a strong magnetic field is added.SOLUTION: A magnetic sensor includes: magnetic field detection parts having magnetic detection elements; first and second magnetic shields positioned in a manner to sandwich the magnetic field detection parts in a first direction; and third magnetic shields positioned lateral to the magnetic field detection parts in a second direction orthogonal to the first direction.SELECTED DRAWING: Figure 1A

Description

[Technical field]

[0001] The present disclosure relates to magnetic sensors. [Background technology]

[0002] In recent years, physical quantity detection devices (position detection devices) for detecting physical quantities (such as the position or amount of movement (amount of change) due to rotational or linear movement of a moving body) have been used in various applications. Known examples of such physical quantity detection devices include a magnetic sensor capable of detecting changes in an external magnetic field, and a magnetic field generating unit (such as a magnet) capable of changing the position relative to the magnetic sensor, and a sensor signal corresponding to the change in the external magnetic field is output from the magnetic sensor.

[0003] A known magnetic sensor has a magnetic sensor element that detects the magnetic field to be detected and is provided on a substrate. Such a magnetic sensor element may be a magnetoresistive effect element (GMR element, TMR element, etc.) whose resistance changes in response to changes in the external magnetic field.

[0004] The magnetoresistance effect element is configured with a laminated structure having at least a free layer whose magnetization direction can be changed in response to an external magnetic field, a magnetization fixed layer whose magnetization direction is fixed, and a non-magnetic layer interposed between the free layer and the magnetization fixed layer. In a magnetoresistance effect element having such a structure, the resistance value of the magnetoresistance effect element is determined by the angle between the magnetization direction of the free layer and the magnetization fixed layer. The magnetization direction of the free layer changes in response to an external magnetic field, and the angle between the magnetization directions of the free layer and the magnetization fixed layer changes accordingly, thereby changing the resistance value of the magnetoresistance effect element. This change in resistance value outputs a sensor signal in response to the change in the external magnetic field. The magnetoresistance effect element provided on a substrate is often configured to be sensitive to a magnetic field parallel to the surface of the substrate.

[0005] On the other hand, there is also a demand for a magnetic sensor that detects a magnetic field perpendicular to the surface of the substrate using a magnetoresistance effect element provided on the substrate. For example, Patent Document 1 discloses a magnetic sensor that has a magnetic shield that blocks an external magnetic field along the surface of the substrate, a magnetic field detection unit, and a magnetic field conversion unit that converts a magnetic field component perpendicular to the substrate surface into a magnetic field component in the surface direction of the substrate and applies the magnetic field to the magnetic field detection unit.

[0006] Patent Document 2 discloses a magnetic shield for minimizing interference from an external magnetic field in the perpendicular and planar directions for a magnetic device such as a vertically oriented magnetoresistive random access memory (MRAM). However, the technology described in Patent Document 2 is a technology for shielding the MRAM from interference from an external magnetic field, and is fundamentally different from the magnetic shield technology used for a magnetic sensor that detects an external magnetic field. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] JP 2022-123321 A [Patent Document 2] US Patent Application Publication No. 2023 / 0014296 Summary of the Invention [Problem to be solved by the invention]

[0008] In recent years, camera modules such as optical image stabilization (OIS) require stronger driving force due to the increasing size of lenses. This has resulted in stronger magnetic fields being generated by the driving magnets of the modules. In such an environment, the strength of the detected magnetic field also becomes stronger, and the magnetic sensors used are required to have a wider magnetic field detection range.

[0009] However, when the magnetic field perpendicular to the substrate surface is strong, a problem occurs in that the magnetic field detection range of the magnetic sensor (hereinafter also referred to as the "Z-axis magnetic sensor") that detects the magnetic field perpendicular to the substrate surface is reduced. This is because, when a strong magnetic field perpendicular to the substrate surface (hereinafter also referred to as the "Z magnetic field") is applied to the Z-axis magnetic sensor, the magnetization of the free layer of the TMR element begins to rotate in the Z direction, for example, causing a decrease in output. Such rotation of the free layer magnetization is an obstacle to expanding the detection range of the Z magnetic field.

[0010] In particular, when magnetic shields that block external magnetic fields along the surface direction of the substrate are placed above and below the TMR element, the magnetic flux in the Z direction is converged by the magnetic shields, and a stronger Z magnetic field is applied to the TMR element, which causes the problem that the detection magnetic field range is likely to be further reduced.

[0011] The present disclosure has been made in consideration of the above circumstances, and has an object to provide a magnetic sensor in which the detection magnetic field range is unlikely to decrease even when a strong Z magnetic field is applied. [Means for solving the problem]

[0012] A magnetic sensor according to one embodiment of the present disclosure includes a magnetic field detection unit having a magnetic detection element, a first magnetic shield and a second magnetic shield positioned to sandwich the magnetic field detection unit in a first direction, and a third magnetic shield positioned to the side of the magnetic field detection unit in a second direction perpendicular to the first direction.

[0013] Furthermore, a magnetic sensor according to one embodiment of the present disclosure includes a magnetic field detection unit having a magnetic detection element, a first magnetic shield and a second magnetic shield positioned to sandwich the magnetic field detection unit in a first direction, and a third magnetic shield that converges magnetic flux in the first direction and reduces the magnetic flux applied to the magnetic field detection unit.

[0014] In the magnetic sensor according to the aspect of the present disclosure, a part or an entirety of the third magnetic shield may be located between the first magnetic shield and the second magnetic shield, and the third magnetic shield may have a flat shape in the second direction perpendicular to the first direction.

[0015] The magnetic sensor according to the aspect of the present disclosure may include a plurality of the magnetic field detection units, and the third magnetic shield may be formed for each of the plurality of magnetic field detection units.

[0016] The magnetic sensor according to one aspect of the present disclosure may further include a magnetic field conversion unit that converts a magnetic field component in the first direction into a magnetic field component in a second direction perpendicular to the first direction and applies the magnetic field component to the magnetic field detection unit.

[0017] In the magnetic sensor according to the embodiment of the present disclosure, when viewed from a direction perpendicular to a first direction, the position of the magnetic field conversion unit may overlap the position of the third magnetic shield. Also, when viewed from a direction perpendicular to the first direction, the position of the magnetic field detection unit may overlap the position of the third magnetic shield, and in the first direction, the position of the magnetic field detection unit may overlap a center position of the third magnetic shield.

[0018] In the magnetic sensor according to the aspect of the present disclosure, the magnetic detection element may be positioned at an angle with respect to the second direction perpendicular to the first direction.

[0019] The magnetic sensor according to one aspect of the present disclosure may include a plurality of the magnetic field detection units, and the plurality of the magnetic field detection units may be connected by a bridge circuit.

[0020] In a magnetic sensor according to one embodiment of the present disclosure, the third magnetic shield may be in contact with one or both of the first magnetic shield and the second magnetic shield, or the third magnetic shield may be spaced apart from one or both of the first magnetic shield and the second magnetic shield.

[0021] In the magnetic sensor according to the aspect of the present disclosure, the third magnetic shield may surround the magnetic field detection unit in the second direction perpendicular to the first direction.

[0022] A camera module according to an embodiment of the present disclosure includes an autofocus mechanism and / or an optical image stabilization mechanism equipped with the above-described magnetic sensor. Effect of the Invention

[0023] According to the present disclosure, it is possible to provide a magnetic sensor in which the detection magnetic field range is unlikely to decrease even when a strong Z magnetic field is applied. [Brief description of the drawings]

[0024] [Figure 1A] FIG. 1A is a perspective view showing a schematic configuration of a magnetic sensor according to the present embodiment. [Figure 1B] FIG. 1B is a plan view of the magnetic sensor in FIG. 1A. [Figure 2A] FIG. 2A is a schematic diagram showing the convergence of magnetic flux in the Z direction by a first magnetic shield and a second magnetic shield. [Figure 2B] FIG. 2B is a schematic diagram showing an aspect in which the third magnetic shield forms a magnetic path and reduces the first magnetic field component applied to the magnetic field detection unit. [Figure 2C] FIG. 2C is a diagram showing a Z magnetic field simulation when a Z-direction magnetic field of 500 mT is applied. [Figure 3A] FIG. 3A is a perspective view showing a schematic configuration of the magnetic sensor according to this embodiment. [Figure 3B] FIG. 3B is a side view showing a schematic configuration of the magnetic sensor according to this embodiment. [Figure 3C] FIG. 3C is a side view showing a schematic configuration of the magnetic sensor according to this embodiment. [Figure 3D] FIG. 3D is a side view showing a schematic configuration of the magnetic sensor according to this embodiment. [Figure 3E] FIG. 3E is a side view showing a schematic configuration of the magnetic sensor according to this embodiment. [Figure 3F] FIG. 3F is a side view showing a schematic configuration of the magnetic sensor according to this embodiment. [Figure 3G] FIG. 3G is a side view showing a schematic configuration of the magnetic sensor according to this embodiment. [Figure 3H] FIG. 3H is a side view showing a schematic configuration of the magnetic sensor according to this embodiment. [Figure 3I] FIG. 3I is a partial enlarged view of the range S in FIG. 3H. [Figure 3J] FIG. 3J is a schematic diagram showing a calculation formula for the resistance R of a magnetoresistive element. [Figure 3K] FIG. 3K is a schematic diagram showing a calculation formula for the resistance R of the magnetoresistive element. [Figure 4A] FIG. 4A is a plan view showing a schematic configuration of the magnetic sensor according to this embodiment. [Figure 4B] FIG. 4B is a plan view showing a schematic configuration of the magnetic sensor according to this embodiment. [Figure 4C] FIG. 4C is a plan view showing a schematic configuration of the magnetic sensor according to this embodiment. [Figure 4D] FIG. 4D is a plan view showing a schematic configuration of the magnetic sensor according to this embodiment. [Diagram 5] FIG. 5 is a plan view illustrating an example of a magnetic sensor configured as a magnetic compass. [Figure 6A] FIG. 6A is a perspective view showing an example of a magnetic sensor used as a part of an autofocus mechanism and an optical image stabilization mechanism of a camera module. [Figure 6B] FIG. 6B is a cross-sectional view showing the internal structure of the camera module shown in FIG. 6A. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0025] Hereinafter, an embodiment of the present disclosure (hereinafter also referred to as "the present embodiment") will be described with reference to the drawings. In addition, in the drawings attached to this specification, the scale and the aspect ratio may be appropriately changed and exaggerated from those of the actual objects for the convenience of illustration and ease of understanding.

[0026] As necessary, the "X direction", "Y direction", "Z direction", and "XY plane direction" are specified. Here, the "XY plane direction" is the plane direction of the substrate on which the magnetic sensor is configured, and is also the plane direction of the first magnetic shield or the second magnetic shield in one embodiment of the present disclosure. The "X direction" and the "Y direction" are directions perpendicular to each other in the XY plane. Furthermore, the "Z direction" is the thickness direction of the substrate on which the magnetic sensor is configured, and is also a direction perpendicular to the XY plane direction.

[0027] In addition, the "first direction" in this disclosure may be the Z direction, and the "second direction" may be any direction on the XY plane.

[0028] The terms and / or values ​​that mean the shape and / or geometric conditions do not need to be bound by strict meanings, and may be interpreted as including a range within which similar functions may be expected. For example, "parallel" and / or "orthogonal" fall under the above terms. Also, "length value" and / or "angle value" fall under the above numerical values.

[0029] When a certain configuration is expressed as being "above," "below," "upper," "lower," "above," or "below" another configuration, this may include a configuration in which the certain configuration is in direct contact with the other configuration, and a configuration in which another configuration is included between the certain configuration and the other configuration. In other words, a configuration in which another configuration is included between the certain configuration and the other configuration may be expressed as a configuration indirectly in contact with the other configuration. Furthermore, the expressions "above," "upper side," or "above" can be exchanged for the expressions "below," "lower side," or "below." In other words, the up-down direction may be reversed. The same applies to the left and right.

[0030] When the same or similar symbols are used for the same parts and / or parts having similar functions, repeated description may be omitted. In addition, the dimensional ratios in the drawings may differ from the actual ratios. In addition, part of the configuration of the embodiment may be omitted from the drawings.

[0031] One or more of the embodiments may be combined with one or more of the modified examples as long as no contradictions arise. Also, one or more of the embodiments may be combined with each other as long as no contradictions arise. Also, one or more of the modified examples may be combined with each other as long as no contradictions arise.

[0032] When a plurality of steps are disclosed for a method such as a manufacturing method, other steps that are not disclosed may be performed between the disclosed steps. In addition, the order of the steps is not limited to the extent that no contradiction occurs.

[0033] Fig. 1A is a perspective view showing a schematic configuration of a magnetic sensor 100 according to an embodiment of the present disclosure. Fig. 1B shows a plan view of the magnetic sensor 100 in Fig. 1A from the first magnetic shield 131 side. The first magnetic shield 131 is not shown in Fig. 1B.

[0034] 1A and 1B, the magnetic sensor 100 has a magnetic field conversion unit 110, a magnetic field detection unit 120, and a magnetic shield 130. As shown in Fig. 1A, the magnetic shield 130 has a first magnetic shield 131 and a second magnetic shield 132 located above and below the magnetic field detection unit 120 in the Z direction, and a third magnetic shield 133 located on the left and right of the magnetic field detection unit 120 in the X direction. Each component will be described in detail below.

[0035] The magnetic field conversion unit 110 converts a magnetic field component in the Z direction (hereinafter also referred to as a "first magnetic field component H1") into a magnetic field component in an arbitrary direction on the XY plane (hereinafter also referred to as a "second magnetic field component H2"), and applies the second magnetic field component H2 to the magnetic field detection unit 120. This enables the magnetic field detection unit 120 to output a signal according to a change in the first magnetic field component H1.

[0036] The positional relationship between the magnetic field conversion unit 110 and the magnetic field detection unit 120 is not particularly limited, but the magnetic field detection unit 120 may be provided at a position where the output magnetic field from the magnetic field conversion unit 110 can be applied. Furthermore, one magnetic field conversion unit 110 may be provided for one magnetic field detection unit 120, or one magnetic field conversion unit 110 may be provided for multiple magnetic field detection units 120.

[0037] The magnetic field conversion unit 110 may be configured with one or more yokes 111 made of a soft magnetic material. In Fig. 1A and Fig. 1B, the yoke 111 is shown as a rectangular parallelepiped extending in the Y direction, but the shape of the yoke 111 is not particularly limited as long as it can apply the second magnetic field component H2 to the magnetic field detection unit 120.

[0038] The material constituting the yoke 111 is not particularly limited, but may be, for example, a soft magnetic material such as permalloy (NiFe).

[0039] The magnetic field detection unit 120 outputs a signal according to the second magnetic field component H2. Here, the second magnetic field component H2 is obtained by converting the first magnetic field component H1 by the magnetic field conversion unit 110. In addition, the magnetic field detection unit 120 is shielded from an external magnetic field in the XY plane direction by a first magnetic shield 131 and a second magnetic shield 132 described later. Therefore, the signal output by the magnetic field detection unit 120 is a signal according to a change in the first magnetic field component H1.

[0040] The magnetic field detection unit 120 may have one or more magnetic detection elements 121. The magnetic detection element may be any element having a function of detecting a magnetic field, such as a tunnel magnetoresistance element (TMR element), a giant magnetoresistance element (GMR element), an anisotropic magnetoresistance element (AMR element), a Hall element, or other types of magnetic detection elements. Among these, the TMR element is particularly suitable for the magnetic detection element 121, since it has a smaller junction area than other types of MR elements, allowing the sensor chip to be miniaturized, and has a larger MR ratio, allowing the output of the sensor chip to be increased.

[0041] 1A and 1B, the number and arrangement of the magnetic detection elements 121 in the magnetic field detection unit 120 are merely examples and are not limited thereto. For example, the magnetic field detection unit 120 may have one magnetic detection element 121, or may have an element row in which a plurality of magnetic detection elements 121 arranged in a matrix are electrically connected in series. In FIGS. 1A and 1B, the magnetic field detection unit 120 is shown as an element row in which a plurality of magnetic detection elements 121 are electrically connected in series.

[0042] The magnetic sensor 100 may also have a plurality of magnetic field detection units 120. For example, the magnetic sensor 100 may have four magnetic field detection units 120, and the four magnetic field detection units 120 may be bridge-connected to each other to form a bridge circuit such as a Wheatstone bridge circuit. The magnetic sensor 100 may also have four magnetic field detection unit groups, each group including a plurality of magnetic field detection units 120, and the four magnetic field detection unit groups may be bridge-connected to each other to form a Wheatstone bridge circuit. In the magnetic field detection unit group, the plurality of magnetic field detection units 120 may be connected in series or in parallel.

[0043] For example, FIG. 1B illustrates an embodiment in which the magnetic sensor 100 has four magnetic field detection units, a first magnetic field detection unit group R1, a second magnetic field detection unit group R2, a third magnetic field detection unit group R3, and a fourth magnetic field detection unit group R4. The Wheatstone bridge circuit illustrated in FIG. 1B includes a power supply port V, a ground port G, a first output port E1, a second output port E2, a first magnetic field detection unit R1 provided between the power supply port V and the first output port E1, a second magnetic field detection unit R2 provided between the first output port E1 and the ground port G, a third magnetic field detection unit R3 provided between the power supply port V and the second output port E2, and a fourth magnetic field detection unit R4 provided between the second output port E2 and the ground port G. A constant current source is connected to the power supply port V, so that a power supply voltage (constant current) of a predetermined magnitude is applied, and the ground port G is connected to the ground. The constant current supplied to the power supply port V is controlled to a predetermined current value by a driver IC (not shown). A constant voltage may be applied to the power supply port V.

[0044] In the bridge configuration shown in FIG. 1B, the direction of the magnetic field bent by the yoke and the direction of the magnetization fixed layer may be combined as follows to obtain an output. For example, when a magnetic field in the Z direction from the second magnetic shield 132 side to the first magnetic shield 131 side is applied, the resistance of each magnetic field detection unit group changes as follows. In the first magnetic field detection unit group R1, the free layer magnetization changes to a direction antiparallel to the magnetization fixed layer magnetization, and the resistance increases. In the second magnetic field detection unit group R2, the free layer magnetization changes to a direction parallel to the magnetization fixed layer magnetization, and the resistance decreases. In the third magnetic field detection unit group R3, the free layer magnetization changes to a direction parallel to the magnetization fixed layer magnetization, and the resistance decreases. In the fourth magnetic field detection unit group R4, the free layer magnetization changes to a direction antiparallel to the magnetization fixed layer magnetization, and the resistance increases. The magnitude of the relative angle between the free layer magnetization and the magnetization of the fixed layer at this time changes depending on the strength of the applied Z magnetic field, and as a result, the magnitude of the Z magnetic field can be obtained in the form of a differential potential (E1-E2) in the Wheatstone bridge circuit due to the change in resistance of the magnetic field detection parts.

[0045] The magnetic field detection unit 120 may be positioned parallel to the XY plane direction as shown in Fig. 1A and Fig. 1B, or may be positioned inclined to the XY plane direction as shown in Fig. 3H. When the magnetic field detection unit 120 is positioned parallel to the XY plane direction, the manufacturing efficiency tends to be improved compared to when the magnetic field detection unit 120 is positioned inclined to the XY plane direction. In addition, when the magnetic field detection unit 120 is positioned inclined to the XY plane direction, the magnetic field conversion unit 110 may not be an essential component.

[0046] More specifically, as shown in Fig. 3I, in the partially enlarged view of the range S in Fig. 3H, the magnetic field detection unit 120 positioned at an angle θ can detect the magnetic field component Bz in the Z direction as Bz sin θ. Therefore, for the magnetic field detection unit 120 positioned at an angle θ, it is not necessary to convert the magnetic field component in the Z direction into a magnetic field component in an arbitrary direction on the XY plane using the magnetic field conversion unit 110.

[0047] In addition, by adopting such a configuration without the magnetic field conversion unit 110, a relatively uniform magnetic field can be applied compared to the case where the magnetic field conversion unit 110 is provided. For example, the magnetic field component in the Z direction is converted into a magnetic field component in an arbitrary direction on the XY plane by the yoke 111. At this time, the strength of the magnetic field component in an arbitrary direction on the XY plane applied to the magnetic field detection unit 120 changes according to the distance from the yoke 111 in the XY plane direction. Therefore, a non-uniform in-plane magnetic field is applied to the magnetic field detection unit 120 in the XY plane direction. More specifically, for example, the magnetic field component converted into the plane is large near the end of the yoke 111, while the in-plane magnetic field component decreases as it moves away from the end of the yoke 111 to the outside. Therefore, when comparing the end of the magnetic field detection unit 120 close to the end of the yoke 111 with the end of the magnetic field detection unit 120 far from the end of the yoke 111, the former receives a large in-plane magnetic field, and the latter receives a relatively weak in-plane magnetic field. In contrast, by arranging the magnetic field detection unit 120 at an angle to the XY plane direction and not providing a magnetic field conversion unit 110, the problem of in-plane magnetic field non-uniformity due to the distance from the yoke 111 can be avoided, and the effect of the in-plane magnetic field non-uniformity on the linearity of the resistance change of the magnetic field detection unit 120 can be avoided.

[0048] The first magnetic shield 131 and the second magnetic shield 132 are positioned to sandwich the magnetic field detection unit 120 when viewed along the Z direction. That is, the first magnetic shield 131 and the second magnetic shield 132 overlap with the magnetic field detection unit 120 in the Z direction. As a result, the magnetic flux in the XY plane direction is converged by the first magnetic shield 131 and the second magnetic shield 132, and the magnetic field detection unit 120 is shielded from the external magnetic field in the XY plane direction. Therefore, the magnetic field in the Z direction is effectively applied to the magnetic field detection unit 120.

[0049] As long as the effects of the magnetic sensor 100 in this embodiment are achieved, the first magnetic shield 131 and the second magnetic shield 132 may overlap a part of the magnetic field detection unit 120 in the Z direction, or may overlap the entire magnetic field detection unit 120. The first magnetic shield 131 may overlap a part of the second magnetic shield 132 in the Z direction, or may overlap the entire second magnetic shield 132.

[0050] The shape of the first magnetic shield 131 and the second magnetic shield 132 in the XY plane direction is not particularly limited, and examples thereof include a square shape, a quadrangle shape with four corners of 89 to 91 degrees, a rounded rectangular shape with four rounded corners, a rectangular shape with four chamfered corners (octagonal shape), an oval shape including an ellipse, a rectangular shape with two opposing short sides formed into arcs, a trapezoid, a parallelogram, a rhombus, and the like. When the first magnetic shield 131 and the second magnetic shield 132 have a quadrangle shape, at least one pair of opposing two sides out of two pairs of opposing two sides may be parallel, or the two pairs of opposing two sides may be non-parallel. The shapes of the first magnetic shield 131 and the second magnetic shield 132 in the XY plane direction may be the same or different.

[0051] Furthermore, the first magnetic shield 131 and the second magnetic shield 132 may be configured as a single magnetic shield as shown in Figures 1A and 1B, or may be configured as multiple magnetic shields arranged in parallel in the XY plane direction.

[0052] As described above, the first magnetic shield 131 and the second magnetic shield 132 block the magnetic field in the XY plane direction with respect to the magnetic field detection unit 120, but on the other hand, the first magnetic shield 131 and the second magnetic shield 132 converge the magnetic flux in the Z direction. Therefore, as shown in Fig. 2A, a stronger magnetic field in the Z direction is applied to the magnetic field detection unit 120 located between the first magnetic shield 131 and the second magnetic shield 132.

[0053] As described above, the mechanism by which the detection magnetic field range of the TMR in the Z direction decreases as the first magnetic field component H1 increases will be described in more detail with reference to FIG. 3J and FIG. 3K. In general, the resistance R of the TMR can be expressed by the difference between the magnetization angle θfree of the free layer and the magnetization angle θpin of the magnetization fixed layer, and the conductance G of the TMR and the amplitude dG of the conductance fluctuation. For simplicity, FIG. 3J shows a case where the magnetization angle θpin is 0. In this embodiment, the magnetic field conversion unit 110 converts a part of the first magnetic field component H1 in the Z direction into a second magnetic field component H2 in an arbitrary direction on the XY plane and applies it to the magnetic field detection unit 120. When only the second magnetic field component H2 is applied, the magnetization of the free layer rotates in the plane and the magnetization angle θfree changes. The calculation formula for the resistance R at this time is shown in FIG. 3J.

[0054] On the other hand, as the magnetic field in the Z direction becomes stronger, i.e., as the first magnetic field component H1 becomes larger, the magnetization of the free layer rotates in-plane due to the second magnetic field component H2 and at the same time rotates by the magnetic field angle Φfree with respect to the XY plane due to the first magnetic field component H1, as shown in FIG. 3K. As a result, as shown in FIG. 3K, when the first magnetic field component H1 is small, i.e., when Φfree is close to zero, Cos(Φfree) is almost 1 and contributes little to the variation of the resistance R. However, as the first magnetic field component H1 becomes larger, the magnetic field angle Φfree approaches 90 degrees, and as a result, Cos(Φfree) approaches zero. This reduces the variation range of the resistance R, resulting in a decrease in the detection magnetic field range of the magnetic field in the Z direction.

[0055] Therefore, in the magnetic sensor 100 according to the embodiment of the present disclosure, as shown in FIG. 2B, a third magnetic shield 133 is used. This allows the third magnetic shield 133 to form a magnetic path and reduce the first magnetic field component H1 applied to the magnetic field detection unit 120. As a result, even if the magnetic field in the Z direction is strong, it is possible to suppress the output reduction caused by the magnetization of the free layer rotating in the perpendicular direction, and to improve the detection magnetic field range. Note that in FIG. 2B, the magnetic field conversion unit 110 and the magnetic field detection unit 120 are omitted.

[0056] Next, the third magnetic shield 133 will be described in detail. The third magnetic shield 133 is located on the side of the magnetic field detection unit 120 in the XY plane direction. That is, the third magnetic shield 133 does not overlap with the magnetic field detection unit 120 in the Z direction. This third magnetic shield 133 converges the magnetic flux in the Z direction between the first magnetic shield 131 and the second magnetic shield 132, and forms a magnetic path in the Z direction. Therefore, a part of the first magnetic field component H1 applied to the magnetic field detection unit 120 is converged by the third magnetic shield 133, and the magnetic field intensity of the first magnetic field component H1 applied to the magnetic field detection unit 120 is reduced. This suppresses the decrease in the detection magnetic field range, and realizes the magnetic sensor 100 with a wide detection magnetic field range in the Z direction.

[0057] FIG. 2C shows a Z magnetic field simulation when a Z-direction magnetic field is applied. The vertical axis of FIG. 2C shows the ratio of the Z-direction magnetic field Bz at the measurement position to the external Z magnetic field Bz_ext. As shown in FIG. 2C, Model 1 using a combination of the first magnetic shield 131, the second magnetic shield 132, and the third magnetic shield 133 stabilizes the formation of the magnetic path in the Z direction and provides an excellent effect of suppressing the decrease in the detection magnetic field range in the Z direction, compared to Models 2 to 4 lacking any of the first magnetic shield 131, the second magnetic shield 132, and the third magnetic shield 133.

[0058] Furthermore, as shown in FIG. 2C, Model 1, which uses a combination of the first magnetic shield 131, the second magnetic shield 132, and the third magnetic shield 133, can obtain a more uniform magnetic field strength in the Z direction at any position in the XY plane direction, compared to, for example, Models 2 and 4, which do not have one or both of the first magnetic shield 131 and the second magnetic shield 132. Therefore, it is possible to reduce the variation in sensitivity due to the difference in the arrangement position of the magnetic field detection unit 120 in the XY plane direction. As a result, even if the installation position of the magnetic detection element 121 in the XY plane direction is shifted in the manufacturing process, it is possible to suppress the sensitivity variation due to the shift. Furthermore, as shown in FIG. 1B, when multiple magnetic detection elements 121 are widely arranged, the sensitivity variation due to the difference in the arrangement position of the magnetic detection elements 121 is also suppressed.

[0059] The first magnetic shield 131, the second magnetic shield 132, and the third magnetic shield 133 may be integrated, or may not be integrated but may be magnetically coupled.

[0060] The constituent materials of the first magnetic shield 131, the second magnetic shield 132, and the third magnetic shield 133 are not particularly limited, but may be, for example, a soft magnetic material such as permalloy (NiFe).

[0061] Next, the third magnetic shield 133 will be further described. FIGS. 3A to 3H show the third magnetic shield 133 in the Z direction. FIGS. 3A to 3H are side views showing a schematic configuration of the magnetic sensor 100. FIGS. 4A to 4D show the third magnetic shield 133 in a cross section parallel to the XY plane. FIGS. 4A to 4D show plan views of the magnetic sensor 100 from the first magnetic shield 131 side. Note that the first magnetic shield 131 is not shown in FIGS. 4A to 4D.

[0062] 3A, the entire third magnetic shield 133 may be located between the first magnetic shield 131 and the second magnetic shield 132. Also, as shown in FIG. 3B, a part of the third magnetic shield 133 may be located between the first magnetic shield 131 and the second magnetic shield 132. In other words, a part of the third magnetic shield 133 does not have to be located between the first magnetic shield 131 and the second magnetic shield 132.

[0063] 3C , as long as the effects of the magnetic sensor 100 in this embodiment are achieved, the third magnetic shield 133 does not have to be located between the first magnetic shield 131 and the second magnetic shield 132. In FIG. 3C , the third magnetic shield 133 is spaced apart from the first magnetic shield 131 and the second magnetic shield 132 in the X direction, but the third magnetic shield 133 may be in contact with the first magnetic shield 131 and the second magnetic shield 132.

[0064] 3A to 3C, when the entire third magnetic shield 133 is not located between the first magnetic shield 131 and the second magnetic shield 132 as shown in FIG. 3C, the third magnetic shield 133 acts like a yoke with respect to the XY in-plane magnetic field, and saturation of the first magnetic shield 131 and the second magnetic shield 132 with respect to the XY magnetic field tends to be promoted. On the other hand, when the entire third magnetic shield 133 is located between the first magnetic shield 131 and the second magnetic shield 132 as shown in FIG. 3A, saturation of the first magnetic shield 131 and the second magnetic shield 132 with respect to the XY magnetic field tends not to be promoted. In addition, the third magnetic shield 133 also tends not to be saturated with respect to the XY magnetic field.

[0065] As shown in Fig. 3D, the third magnetic shield 133 may be located between the first magnetic shield 131 and the second magnetic shield 132 and in contact with the first magnetic shield 131. Also, as shown in Fig. 3E, the third magnetic shield 133 may be located between the first magnetic shield 131 and the second magnetic shield 132 and in contact with the second magnetic shield 132. Furthermore, as shown in Fig. 3F, the third magnetic shield 133 may be located between the first magnetic shield 131 and the second magnetic shield 132 and in contact with both the first magnetic shield 131 and the second magnetic shield 132.

[0066] Alternatively, as shown in FIG. 3A, the third magnetic shield 133 may be located between the first magnetic shield 131 and the second magnetic shield 132 and spaced apart from both the first magnetic shield 131 and the second magnetic shield 132.

[0067] As shown in FIG. 3A, the third magnetic shield 133 may have a flat shape in the XY plane direction. When the third magnetic shield 133 has a flat shape in the XY plane direction, the length of the third magnetic shield 133 in the Z direction is shorter than the length of the third magnetic shield 133 in the XY plane direction. This makes the Z direction the hard axis of the shape magnetic anisotropy, so that the magnetization of the third magnetic shield 133 in the Z direction is less likely to be saturated. Therefore, the magnetic field strength of the first magnetic field component H1 applied to the magnetic field detection unit 120 tends to be effectively reduced to a stronger magnetic field.

[0068] In the Z direction, the position h1 of the third magnetic shield 133 may overlap the position h2 of the magnetic field conversion unit 110 as shown in FIG. 3A, or may not overlap as shown in FIG. 3E. Among these, it is preferable that the position h1 of the third magnetic shield 133 in the Z direction overlaps the position h2 of the magnetic field conversion unit 110 in the Z direction. This makes it difficult for the magnetic field component in the XY plane direction by the third magnetic shield 133 to be applied to the magnetic field conversion unit 110. Therefore, the detection accuracy of the magnetic field detection unit 120 tends to be further improved. The position h1 of the third magnetic shield 133 in the Z direction is a portion of the third magnetic shield 133 sandwiched between the surface 133a on the first magnetic shield 131 side and the surface 133b on the second magnetic shield 132 side. The position h2 of the magnetic field conversion unit 110 in the Z direction is a portion of the magnetic field conversion unit 110 sandwiched between the surface 110a on the first magnetic shield 131 side and the surface 110b on the second magnetic shield 132 side. The position h1 and the position h2 overlap means that at least one of the surface 133a and the surface 133b is located between the surface 110a and the surface 110b.

[0069] In the Z direction, the position h1 of the third magnetic shield 133 may overlap the position h3 of the magnetic field detection unit 120 as shown in FIG. 3A, or may not overlap as shown in FIG. 3D. Among these, it is preferable that the Z direction position h1 of the third magnetic shield 133 overlaps the Z direction position h3 of the magnetic field detection unit 120 when viewed from a direction perpendicular to the Z direction. In particular, it is preferable that the Z direction center position h1' of the third magnetic shield 133 overlaps the Z direction position h3 of the magnetic field detection unit 120 when viewed from a direction perpendicular to the Z direction as shown in FIG. 3A. This makes it difficult for the magnetic field detection unit 120 to apply the magnetic field component converted into the XY plane direction by the third magnetic shield 133 when the Z magnetic field is applied. Therefore, the detection accuracy of the magnetic field detection unit 120 tends to be further improved. Note that position h3 in the Z direction of the magnetic field detection unit 120 is a portion of the magnetic field detection unit 120 that is sandwiched between surface 120a on the first magnetic shield 131 side and surface 120b on the second magnetic shield 132 side. The central position h1' overlapping with position h3 means that surface 133c at the central position h1' is located between surface 120a and surface 120b.

[0070] The third magnetic shield 133 may be positioned at the edges of the first magnetic shield 131 and the second magnetic shield 132 as shown in Figures 3A to 3F, or may be positioned behind the edges of the first magnetic shield 131 and the second magnetic shield 132, for example in the center, as shown in Figure 3G.

[0071] As shown in Fig. 4A, the third magnetic shield 133 may be positioned so as to surround all edges of the first magnetic shield 131 and the second magnetic shield 132. In other words, the third magnetic shield 133 may be positioned so as to surround the magnetic field detection unit 120. Also, as shown in Fig. 4B, the third magnetic shield 133 may be positioned so as to surround part of edges of the first magnetic shield 131 and the second magnetic shield 132. In other words, the third magnetic shield 133 may be positioned so as to partially surround the magnetic field detection unit 120.

[0072] As shown in FIG. 4C, the third magnetic shield 133 does not need to be formed on the edges of the first magnetic shield 131 and the second magnetic shield 132, but may be located behind the edges, for example, in the center.

[0073] 4D , as long as the effects of the magnetic sensor 100 in this embodiment are achieved, the entire third magnetic shield 133 does not have to be located between the first magnetic shield 131 and the second magnetic shield 132. In FIG. 4D , the third magnetic shield 133 is spaced apart from the first magnetic shield 131 and the second magnetic shield 132 in the X direction, but the third magnetic shield 133 may be in contact with the first magnetic shield 131 and the second magnetic shield 132.

[0074] When the magnetic sensor 100 has a plurality of magnetic field detection units 120, the third magnetic shield 133 may be positioned for each magnetic field detection unit 120. In addition, when the first magnetic shield 131 and the second magnetic shield 132 are arranged in parallel in the XY plane direction, the third magnetic shield 133 may be positioned for each combination of the plurality of first magnetic shields 131 and second magnetic shields 132.

[0075] Next, a brief description will be given of a manufacturing method of the magnetic sensor 100. In the process of forming the magnetic detection elements 121, first, a plurality of initial magnetic detection elements are formed, which will later become the plurality of magnetic detection elements 121. Each of the plurality of initial magnetic detection elements includes an initial magnetization fixed layer, which will later become a magnetization fixed layer, a free layer, a gap layer, and an antiferromagnetic layer.

[0076] Next, the magnetization direction of the initial magnetization fixed layer is fixed in a predetermined direction using a laser beam and an external magnetic field of a predetermined direction, whereby the initial magnetization fixed layer becomes the magnetization fixed layer 52, and the initial magnetic detection element becomes the magnetic detection element 121.

[0077] Next, the magnetic sensor chip on which the magnetic detection element 121 is formed in this manner is fixed to a support substrate with an adhesive or the like. Then, a resin layer is formed on the surface of the support substrate so as to cover the magnetic sensor chip. Next, through holes for vias may be opened at the positions of the electrodes in the resin layer, and the support substrate and the magnetic sensor chip may be electrically connected to obtain the magnetic sensor 100.

[0078] The magnetic sensor 100 of the present disclosure may be used as part of an autofocus mechanism or an optical image stabilization mechanism of a camera module.

[0079] Fig. 5 is a diagram showing an example of a magnetic sensor 100 configured as a magnetic compass that generates a detection value corresponding to the angle of the geomagnetic field. As shown in Fig. 5, the magnetic sensor 100 includes three sensor chips 3 (first to third sensor chips 31, 32, and 33), and the first to third sensor chips 31, 32, and 33 are configured to detect components of an external magnetic field in three directions that are orthogonal to each other, respectively.

[0080] Fig. 6A is a perspective view showing an example of a magnetic sensor 100 used as a part of the autofocus mechanism and optical image stabilization mechanism of a camera module 200. Fig. 6B is a side view showing the internal structure of the camera module 200 shown in Fig. 6A. The autofocus mechanism and optical image stabilization mechanism of the camera module 200 includes a driving device 230 that moves a lens 220, and controls the driving device 230 based on position information of the lens 220 detected by a plurality of magnetic sensors 100.

[0081] More specifically, the autofocus mechanism detects when a subject is in focus using an image sensor, an autofocus sensor, etc., and moves the lens in the Z direction relative to the image sensor. The optical image stabilization mechanism detects camera shake using a gyro sensor, etc., and moves the lens in the U direction and / or V direction relative to the image sensor.

[0082] The camera module 200 shown in FIG. 6A includes an image sensor 210 such as a CMOS, a lens 220 that is aligned with the image sensor 210, a first holding member 241 that is movable in the U and V directions relative to the image sensor 210, a second holding member 242 that is movable in the Z direction relative to the first holding member 241, a plurality of elastically deformable wires 244 that support the first holding member 241 and the second holding member 242, a drive device 230 that moves the first holding member 241 and the second holding member 242, and a housing 250 that houses them.

[0083] The autofocus mechanism and optical image stabilization mechanism of the camera module 200 includes, in addition to the driving device 230 and the multiple magnetic sensors 100, a processor that controls the driving device 230, an autofocus sensor that detects the state when the subject is in focus, a gyro sensor that detects camera shake, etc. The processor, autofocus sensor, gyro sensor, etc. (not shown) are arranged outside the housing.

[0084] The lens 220 is fixed inside a cylindrical second holding member 242. The second holding member 242 is accommodated together with the lens 220 in a box-shaped first holding member 241. At least one second magnet 243 is fixed to the second holding member 242 so that at least one magnetic sensor 100 detects position information of the second holding member 242.

[0085] The driving device 230 includes a plurality of first coils 231, a plurality of second coils 232, a plurality of first magnets 233, and the like. The plurality of first coils 231 are fixed to the housing 250. The plurality of second coils 232 are fixed to the second holding member 242. The plurality of first magnets 233 are fixed to the first holding member 241. Each of the plurality of first coils 231 faces a corresponding first magnet 233. Each of the plurality of second coils 232 faces a corresponding first magnet 233.

[0086] In the case of the autofocus mechanism, when a current flows through any second coil 232 in response to a command from the processor, the second holding member 242 fixed to the second coil 232 moves in the Z direction due to the interaction between the magnetic field generated from the first magnet 233 and the magnetic field generated from the second coil 232. At least one magnetic sensor 100 generates a detection signal based on a composite magnetic field obtained by combining the magnetic field generated from at least one second magnet 243 fixed to the second holding member 242 and the magnetic field generated from the first magnet 233 fixed to the first holding member 241, and transmits the detection signal to the processor. The processor detects position information of the lens 220 in the Z direction from the detection signal, and controls the driving device 230 so as to focus on the subject.

[0087] In the case of an optical image stabilization mechanism, when a current flows through any of the first coils 231 in response to a command from the processor, the first holding member 241 fixed to the first magnet 233 moves in the U direction and / or V direction due to the interaction between the magnetic field generated from the first magnet 233 and the magnetic field generated from the first coil 231. Each of the multiple magnetic sensors 100 generates a detection signal based on the position of the corresponding first magnet 233 and transmits it to the processor. The processor detects position information of the lens 220 in the U direction and V direction from the detection signal, and controls the driving device 230 to correct the camera shake.

[0088] The above-described embodiments are intended to facilitate understanding of the present disclosure, and are not intended to limit the present disclosure. The elements of the embodiments, as well as their arrangements, materials, conditions, shapes, sizes, etc., are not limited to those illustrated, and can be changed as appropriate. In addition, configurations shown in different embodiments can be partially substituted or combined with each other.

[0089] For example, the magnetic sensor in this embodiment may be used to detect a position change in the XY plane or a position change in the Z direction from a change in the magnetic field in the Z direction. Examples of applications that include the magnetic sensor include actuators used in robot joint mechanisms, open / close detection mechanisms for notebook computers, joysticks, brushless motors, magnetic encoders, and other electronic devices. [Explanation of symbols]

[0090] 3...sensor chip, 30...magnetic detection element, 31...first sensor chip, 32...second sensor chip, 33...third sensor chip, 52...magnetization fixed layer, 100...magnetic sensor, 110...magnetic field conversion section, 111...yoke, 120...magnetic field detection section, 121...magnetic detection element, 130...magnetic shield, 131...first magnetic shield, 132...second magnetic shield, 133...third magnetic shield, 200...camera module, 210...image sensor, 220...lens, 230...driving device, 231...first coil, 232...second coil, 233...first magnet, 241...first holding member, 242...second holding member, 243...second magnet, 244...wire, 250...housing, 300...magnet.

Claims

1. a magnetic field detection unit having a magnetic detection element; a first magnetic shield and a second magnetic shield positioned to sandwich the magnetic field detection unit in a first direction; a third magnetic shield located to a side of the magnetic field detection unit in a second direction perpendicular to the first direction; Magnetic sensor.

2. a magnetic field detection unit having a magnetic detection element; a first magnetic shield and a second magnetic shield positioned to sandwich the magnetic field detection unit in a first direction; a third magnetic shield that converges the magnetic flux in the first direction and reduces the magnetic flux applied to the magnetic field detection unit; Magnetic sensor.

3. a part or the whole of the third magnetic shield is located between the first magnetic shield and the second magnetic shield; 3. The magnetic sensor according to claim 1 or 2.

4. the third magnetic shield has a flat shape in the second direction perpendicular to the first direction; 3. The magnetic sensor according to claim 1 or 2.

5. The magnetic field detection unit includes a plurality of the magnetic field detection units, The third magnetic shield is formed for each of the plurality of magnetic field detection units.

3. The magnetic sensor according to claim 1 or 2.

6. The magnetic field conversion unit converts the magnetic field component in the first direction into a magnetic field component in a second direction perpendicular to the first direction and applies the magnetic field component to the magnetic field detection unit.

3. The magnetic sensor according to claim 1 or 2.

7. a position of the magnetic field conversion unit overlaps with a position of the third magnetic shield when viewed from a direction perpendicular to the first direction; The magnetic sensor according to claim 6.

8. The magnetic detection element is inclined with respect to the second direction perpendicular to the first direction.

3. The magnetic sensor according to claim 1 or 2.

9. The magnetic field detection unit includes a plurality of the magnetic field detection units, The plurality of magnetic field detection units are connected in a bridge circuit.

3. The magnetic sensor according to claim 1 or 2.

10. a position of the magnetic field detection unit overlaps with a position of the third magnetic shield when viewed from a direction perpendicular to the first direction; 3. The magnetic sensor according to claim 1 or 2.

11. a position of the magnetic field detection unit overlaps with a center position of the third magnetic shield in the first direction when viewed from a direction perpendicular to the first direction; The magnetic sensor according to claim 10.

12. the third magnetic shield is in contact with one or both of the first magnetic shield and the second magnetic shield; 3. The magnetic sensor according to claim 1 or 2.

13. the third magnetic shield is spaced apart from one or both of the first magnetic shield and the second magnetic shield; 3. The magnetic sensor according to claim 1 or 2.

14. the third magnetic shield surrounds the magnetic field detection unit in the second direction perpendicular to the first direction; 3. The magnetic sensor according to claim 1 or 2.

15. An autofocus mechanism and / or an optical image stabilization mechanism including the magnetic sensor according to claim 1 or 2. Camera module.

Images