magnetic sensor

Abstract

To provide a magnetic sensor with which the efficiency of generating a cancel magnetic field is increased.SOLUTION: A magnetic sensor 1 comprises a magnetic body layers M1, M2 that face each other via a magnetic gap G2, a magneto-sensitive element R which is disposed on a magnetic path formed by the magnetic gap G2, and a compensation coil 120 that is wound around the magnetic body layers M1, M2, the magnetic body layers M1, M2, the magneto-sensitive element R, and the compensation coil 120 being integrated on a sensor chip 100. Thus, as the compensation coil 120 is wound around the magnetic body layers M1, M2, the efficiency of generating a cancelling magnetic field is increased. Since the current amount that needs to be flowed to the compensation coil 120 is thereby reduced, it is not only possible to reduce power consumption, but also possible to reduce the heat noise of the magneto-sensitive element R.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present invention relates to a magnetic sensor, and more particularly to a magnetic sensor provided with a compensation coil that cancels a magnetic field to be detected. [Background technology]

[0002] Patent Document 1 discloses a magnetic sensor equipped with a compensation coil that cancels the magnetic field to be detected. In the magnetic sensor described in Patent Document 1, the compensation coil is arranged at a position overlapping the magnetic sensing element so that the compensation coil wraps around the magnetic sensing element. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 2018-179738 Summary of the Invention [Problem to be solved by the invention]

[0004] However, the compensation coil described in Patent Document 1 has low efficiency in generating a cancellation magnetic field, so a large current must be passed through the compensation coil to generate a sufficient cancellation magnetic field, which not only increases power consumption but also poses the problem of increased thermal noise in the magnetic sensing element due to heat generated by the compensation coil.

[0005] SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a magnetic sensor with improved efficiency in generating a canceling magnetic field. [Means for solving the problem]

[0006] The magnetic sensor according to the present invention comprises first and second magnetic layers facing each other via a magnetic gap, a magnetic sensing element arranged on a magnetic path formed by the magnetic gap, and a compensation coil wound around the first and second magnetic layers, and is characterized in that the first magnetic layer, the second magnetic layer, the magnetic sensing element, and the compensation coil are integrated on a sensor chip.

[0007] According to the present invention, the compensation coil integrated on the sensor chip is wound around the magnetic layer, which increases the efficiency of generating the cancellation magnetic field, thereby reducing the amount of current that needs to flow through the compensation coil, thereby reducing not only power consumption but also thermal noise of the magnetic sensing element.

[0008] In the present invention, the sensor chip may have first, second, third, and fourth layers stacked in this order, the compensation coil may include a plurality of lower layer patterns formed on the first layer and a plurality of upper layer patterns formed on the fourth layer, the magnetic sensing element may be formed on the second layer, and the first and second magnetic layers may be formed on the third layer. This increases the efficiency of generating the canceling magnetic field and enables the magnetic field to be detected to be efficiently applied to the magnetic sensing element.

[0009] In the present invention, among the via conductors connecting the lower layer pattern and the upper layer pattern, two adjacent via conductors in a direction perpendicular to the extending direction of the magnetic gap may be positioned at different positions in the extending direction of the magnetic gap, which increases the distance between the adjacent via conductors and makes design and manufacturing easier.

[0010] In the present invention, any of the plurality of lower layer patterns or the plurality of upper layer patterns may overlap with the magnetic sensing element in a plan view, which allows the canceling magnetic field to be applied to the magnetic sensing element efficiently.

[0011] In the present invention, the first and second magnetic layers have a first edge that forms one end in a first direction perpendicular to the extension direction of the magnetic gap and is located on the magnetic gap side, and a second edge that forms the other end in the first direction and is located on the opposite side of the first edge, and the edge of the compensation coil in the first direction may be located at the same position as the second edge or closer to the magnetic gap than the second edge, thereby improving the efficiency of generating the canceling magnetic field.

[0012] The magnetic sensor according to the present invention may further include a first external magnetic body covering the first magnetic layer and a second external magnetic body covering the second magnetic layer, thereby achieving a higher magnetic collection effect. [Effects of the Invention]

[0013] In this way, according to the present invention, it is possible to provide a magnetic sensor with improved efficiency in generating a canceling magnetic field. [Brief explanation of the drawings]

[0014] [Figure 1] FIG. 1 is a schematic perspective view showing the appearance of a magnetic sensor 1 according to one embodiment of the present invention. [Figure 2] FIG. 2 is a schematic exploded perspective view of the magnetic sensor 1. As shown in FIG. [Figure 3] FIG. 3 is a schematic plan view for explaining the configuration of the element formation surface 101 of the sensor chip 100. As shown in FIG. [Figure 4] FIG. 4 is a schematic cross-sectional view taken along the line AA shown in FIG. [Figure 5] FIG. 5 is a schematic cross-sectional view taken along line BB shown in FIG. [Figure 6] FIG. 6 is a schematic plan view for explaining the positional relationship between the magnetic layers M1 and M2 and the magnetic sensing element R. As shown in FIG. [Figure 7] FIG. 7 is a schematic perspective view showing the sensor chip 100 with the magnetic layers M1 and M2 and the compensation coil 120 removed. [Figure 8] FIG. 8 is an XZ cross-sectional view of the main part of the sensor chip 100. As shown in FIG. [Figure 9] FIG. 9 is a circuit diagram showing a circuit for obtaining the detection signal V1. [Figure 10] FIG. 10 is a schematic plan view for explaining the position where the dummy element D1 is arranged. [Figure 11] FIG. 11 is a circuit diagram showing a circuit for obtaining the detection signals V2 and V3. [Figure 12] FIG. 12 is a schematic plan view for explaining the positions where the dummy elements D1 to D3 are arranged. [Figure 13] FIG. 13 is a schematic plan view for explaining the configuration of the element formation surface 101 according to a modified example. [Figure 14] FIG. 14 is a schematic plan view for explaining the configuration of the shape of the magnetic layers M1 and M2 according to the modified example. [Figure 15] FIG. 15 is a schematic plan view for explaining the configuration of the element formation surface 101 according to a modified example. [Figure 16] FIG. 16 is a graph showing the relationship between the positional relationship in the X direction between the magnetic sensing element R and the lower layer pattern 121 and the generation efficiency of the canceling magnetic field. [Figure 17] 17(a) to 17(c) are schematic diagrams for explaining the positional relationship between the magnetic sensing element R and the lower layer pattern 121 in the X direction. [Figure 18] FIG. 18 is a graph showing the relationship between the positional relationship between the edges of the magnetic layers M1 and M2 in the X direction and the edges of the compensation coil 120 in the X direction, and the efficiency of generating a canceling magnetic field. [Figure 19] 19(a) and 19(b) are schematic diagrams for explaining the positional relationship in the X direction between the edge of the magnetic layer M2 and the edge of the upper layer pattern 122. FIG. DETAILED DESCRIPTION OF THE INVENTION

[0015] Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

[0016] 1 is a schematic perspective view showing the appearance of a magnetic sensor 1 according to one embodiment of the present invention, and FIG. 2 is a schematic exploded perspective view of the magnetic sensor 1.

[0017] As shown in FIGS. 1 and 2, the magnetic sensor 1 according to this embodiment includes a substrate 8, and a sensor chip 100 and external magnetic bodies 10 and 20 mounted on the substrate 8. The substrate 8 has an XZ plane as its main surface, and the sensor chip 100 and external magnetic bodies 10 and 20 are mounted on the main surface. The sensor chip 100 has an element forming surface 101 and a back surface 102 located opposite each other and constituting an XY plane, a mounting surface 103 and a top surface 104 located opposite each other and constituting an XZ plane, and side surfaces 105 and 106 located opposite each other and constituting a YZ plane. The sensor chip 100 is mounted upright on the substrate 8 so that the mounting surface 103 faces the main surface of the substrate 8.

[0018] Both external magnetic bodies 10 and 20 are made of a high-magnetic-permeability material such as ferrite. External magnetic body 10 consists of a rod-shaped main body 11 whose longitudinal direction is in the X direction and a protrusion 12 provided at the end of main body 11 in the X direction. Similarly, external magnetic body 20 consists of a rod-shaped main body 21 whose longitudinal direction is in the X direction and a protrusion 22 provided at the end of main body 21 in the X direction. Main body 11 and protrusion 12 may be integral, or may each be made of separate blocks. The same applies to main body 21 and protrusion 22.

[0019] 1 , the sensor chip 100 and the external magnetic body 10 are positioned on the substrate 8 so that a portion of the element forming surface 101 of the sensor chip 100 is covered by the protruding portion 12 of the external magnetic body 10, and a side surface 105 of the sensor chip 100 is covered by an end surface in the X direction of the main body 11 of the external magnetic body 10. Similarly, the sensor chip 100 and the external magnetic body 20 are positioned on the substrate 8 so that another portion of the element forming surface 101 of the sensor chip 100 is covered by the protruding portion 22 of the external magnetic body 20, and a side surface 106 of the sensor chip 100 is covered by an end surface in the X direction of the main body 21 of the external magnetic body 20. As a result, a magnetic gap G1 is formed between the protruding portion 12 and the protruding portion 22.

[0020] Fig. 3 is a schematic plan view for explaining the configuration of the element formation surface 101 of the sensor chip 100. Fig. 4 is a schematic cross-sectional view taken along line AA shown in Fig. 3, and Fig. 5 is a schematic cross-sectional view taken along line BB shown in Fig. 3.

[0021] As shown in FIGS. 3 to 5, the element formation surface 101 of the sensor chip 100 is provided with magnetic layers M1 and M2, a magnetic sensing element R, and a compensation coil 120 wound around the magnetic layers M1 and M2. The magnetic sensing element R is not particularly limited as long as its electrical resistance changes depending on the direction of magnetic flux, and an MR element, for example, can be used. The fixed magnetization direction, which is the sensitivity axis direction of the magnetic sensing element R, is the X direction. The magnetic layers M1 and M2 are thin films made of a NiFe-based material such as permalloy. As shown in FIG. 6, the magnetic layers M1 and M2 are arranged in the X direction with a magnetic gap G2 extending in the Y direction interposed therebetween, and the magnetic sensing element R is positioned so as to overlap with the magnetic gap G2 in a plan view viewed from the Z direction. The width of the magnetic gap G2 in the X direction is narrower than that of the magnetic gap G1. The magnetic layer M1 is covered by the protrusion 12 of the external magnetic body 10, and the magnetic layer M2 is covered by the protrusion 22 of the external magnetic body 20. As a result, the magnetic field in the X direction collected by the external magnetic bodies 10 and 20 passes through the magnetic gap G2 in the X direction, and the magnetic field passing through the magnetic gap G2 is applied to the magnetic sensing element R.

[0022] The sensor chip 100 has a chip body 110 constituting the element forming surface 101, and insulating layers 111, 112, 113, and 114 laminated in this order on the surface of the chip body 110. A plurality of lower layer patterns 121 constituting a compensation coil 120 are provided on the surface of the insulating layer 111 constituting the first layer. A magneto-sensitive element R is provided on the surface of the insulating layer 112 constituting the second layer. Magnetic layers M1 and M2 are provided on the surface of the insulating layer 113 constituting the third layer. A plurality of upper layer patterns 122 constituting the compensation coil 120 are provided on the surface of the insulating layer 114 constituting the fourth layer. The Y-direction end of the lower layer pattern 121 and the Y-direction end of the upper layer pattern 122 are connected by a plurality of via conductors 123 penetrating the insulating layers 112 to 114.

[0023] The lower layer pattern 121 and the upper layer pattern 122 are conductor patterns extending in the Y direction so as to overlap the magnetic layers M1 and M2, but their ends in the Y direction do not overlap the magnetic layers M1 and M2. The Y-direction ends of the lower layer pattern 121 and the upper layer pattern 122 form connection pads whose size in the X direction is enlarged, and via conductors 123 are formed in these connection pads. The lower layer pattern 121 is located below the magnetic layers M1 and M2, i.e., on the -Z direction side, and the upper layer pattern 122 is located above the magnetic layers M1 and M2, i.e., on the +Z direction side. The lower layer pattern 121 and the upper layer pattern 122 are connected via the via conductors 123 to form the compensation coil 120, which is a single continuous coil pattern. In FIG. 3 , the connection pad 124 is one end of the compensation coil 120, and the connection pad 125 is the other end of the compensation coil 120. With this configuration, the magnetic layers M1 and M2 are disposed in the inner diameter region of the compensation coil 120, and therefore, when a current is passed through the compensation coil 120, the resulting canceling magnetic field is applied to the magnetic sensing element R via the magnetic layers M1 and M2. The compensation coil 120 is used to perform so-called closed-loop control by canceling out the magnetic field applied to the magnetic sensing element R. Furthermore, because the magnetic layers M1 and M2 have high magnetic permeability, it is possible to apply a large amount of magnetic flux to the magnetic sensing element R with a small amount of current.

[0024] FIG. 7 is a schematic perspective view showing the sensor chip 100 with the magnetic layers M1 and M2 and the compensation coil 120 removed.

[0025] 7, the magnetic sensing element R extends in the Y direction on the element forming surface 101, and one end thereof is connected to a terminal electrode 131 via a wiring L1, and the other end is connected to a terminal electrode 132 via a wiring L2. The terminal electrodes 133 and 134 are connected to connection pads 124 and 125 of the compensation coil 120, respectively.

[0026] FIG. 8 is an XZ cross-sectional view of the main part of the sensor chip 100. As shown in FIG.

[0027] As shown in FIG. 8, in a plan view seen from the Z direction, the magnetic sensing element R is located between the magnetic layers M1 and M2. This allows the magnetic field passing through the magnetic gap G2 to be applied to the magnetic sensing element R. In other words, the magnetic sensing element R is located near the magnetic gap G2 formed by the magnetic layers M1 and M2 and is positioned on a magnetic path that can detect the target magnetic field passing through the magnetic gap G2. As such, the magnetic sensing element R does not necessarily have to be located between the two magnetic layers M1 and M2; it is sufficient that at least a portion of the magnetic field passing through the magnetic gap G2 formed by the magnetic layers M1 and M2 is applied to the magnetic sensing element R. There are no particular limitations on the relationship between the width of the magnetic gap G2 and the width of the magnetic sensing element R. In the example shown in FIG. 8, the width G2x of the magnetic gap G2 in the X direction is narrower than the width Rx of the magnetic sensing element R in the X direction. As a result, the magnetic layers M1 and M2 and the magnetic sensing element R overlap when viewed from the Z direction, creating an OV. In order to apply as much of the magnetic field passing through the magnetic gap G2 to the magnetic sensing element R, it is desirable that the distance in the Z direction between the magnetic layers M1, M2 and the magnetic sensing element R at the overlap OV be as short as possible, and it is even more desirable that the distance in the Z direction between the magnetic layers M1, M2 and the magnetic sensing element R be shorter than the width G2x of the magnetic gap G2 in the X direction. This makes the magnetic sensing element R the main magnetic path of the magnetic field passing through the magnetic gap G2.

[0028] As shown in FIG. 9, by connecting the magnetic sensing element R and the fixed resistor R10 in series between the power supplies, a detection signal V1 can be obtained from the connection point between them. Then, by passing a compensation current based on the detection signal V1 through the compensation coil 120, closed-loop control can be performed. The fixed resistor R10 may be provided on the sensor chip 100 itself or on the substrate 8. When the fixed resistor R10 is provided on the sensor chip 100 itself, as shown in FIG. 10, a dummy element D1 having the same configuration as the magnetic sensing element R may be provided in a position where it completely overlaps the magnetic layer M1 or the magnetic layer M2, and this dummy element D1 may be used as the fixed resistor R10. Although the dummy element D1 has the same configuration as the magnetic sensing element R, because it completely overlaps the magnetic layer M1 or the magnetic layer M2, almost no magnetic field is applied in the X-direction, which is the magnetic sensing direction, and therefore it can be used as a fixed resistor.

[0029] Alternatively, as shown in Fig. 11, the detection signals V2 and V3 may be obtained by bridge-connecting the magnetic sensing element R and fixed resistors R11 to R13. In this case, as shown in Fig. 12, dummy elements D1 to D3 having the same configuration as the magnetic sensing element R may be provided in positions that completely overlap the magnetic layer M1 or the magnetic layer M2, and these dummy elements D1 to D3 may be used as the fixed resistors R11 to R13.

[0030] As described above, in the magnetic sensor 1 according to this embodiment, the compensation coil 120 is wound around the magnetic layers M1 and M2, which increases the efficiency with which the compensation coil 120 generates a canceling magnetic field. This reduces the amount of current that needs to be passed through the compensation coil 120, which not only reduces power consumption but also reduces thermal noise from the magnetic sensing element R. Moreover, because the magnetic layers M1 and M2, the magnetic sensing element R, and the compensation coil 120 are all integrated on the sensor chip 100, there is no increase in the number of components.

[0031] 3, the multiple via conductors 123 are arranged in a staggered pattern, which means that two via conductors adjacent in the X direction are positioned at different positions in the Y direction, making it possible to increase the number of turns in the compensation coil 120 while ensuring the distance between adjacent via conductors 123. However, in the present invention, it is not essential to arrange the multiple via conductors 123 in a staggered pattern, and depending on the required number of turns in the compensation coil 120 and the design rules for the via conductors 123, the multiple via conductors 123 may be arranged in a row in the X direction, as in the modified example shown in FIG.

[0032] Furthermore, the planar shape of the magnetic layers M1 and M2 is not particularly limited, and they may have a tapered portion whose width in the Y direction narrows as they approach the magnetic gap G2, as in the modified example shown in Fig. 14. Alternatively, as in the modified example shown in Fig. 15, three magnetic layers M1, M2, and M3 may be provided, and the magnetic sensing element R1 may be disposed near the magnetic gap G2 made up of the magnetic layers M1 and M2, and the magnetic sensing element R2 may be disposed near the magnetic gap G3 made up of the magnetic layers M2 and M3.

[0033] FIG. 16 is a graph showing the relationship between the positional relationship in the X direction between the magnetic sensing element R and the lower layer pattern 121 and the generation efficiency of the cancellation magnetic field. The horizontal axis of FIG. 16 represents the difference between the center position in the X direction of the magnetic sensing element R and the center position in the X direction of the lower layer pattern 121 closest to the magnetic sensing element R. As an example, if the width in the X direction of the magnetic sensing element R is 5 μm and the width in the X direction of the lower layer pattern 121 is 30 μm, and their center positions coincide as shown in FIG. 17(a), the difference is 0 μm. Furthermore, as shown in FIG. 17(b), if the center position of the magnetic sensing element R coincides with the edge position of the lower layer pattern 121, the difference is 15 μm. Furthermore, as shown in FIG. 17(c), if the magnetic sensing element R and the lower layer pattern 121 do not overlap and their edge positions coincide, the difference is 17.5 μm. 16, the closer the magnetic field sensing element R and the lower layer pattern 121 are positioned in the X direction, the higher the efficiency of generating the canceling magnetic field, and the highest efficiency of generating the canceling magnetic field is achieved when their central positions coincide. The same applies to the overlap of the magnetic field sensing element R and the upper layer pattern 122. In other words, the efficiency of generating the canceling magnetic field is increased by having either the lower layer pattern 121 or the upper layer pattern 122 overlap with the magnetic field sensing element R in a plan view and by bringing their central positions in the X direction closer together.

[0034] FIG. 18 is a graph showing the relationship between the positional relationship between the X-direction edges of the magnetic layers M1 and M2 and the X-direction edge of the compensation coil 120 and the generation efficiency of the cancellation magnetic field. The horizontal axis of FIG. 18 represents the difference between the X-direction edges of the magnetic layers M1 and M2 and the X-direction edge of the compensation coil 120. Here, the X-direction edges of the magnetic layers M1 and M2 refer to the edges located opposite the edges located on the magnetic gap G2 side. For example, as shown in FIG. 19(a), when the X-direction positions of the edges of the magnetic layer M2 and the upper layer pattern 122 are aligned, the value is 0 μm. Also, as shown in FIG. 19(b), when the edges of the magnetic layer M2 protrude further in the X-direction than the edges of the upper layer pattern 122, that is, when the X-direction edge of the upper layer pattern 122 is located closer to the magnetic gap G2 than the edges of the magnetic layer M2, the value is positive. As shown in FIG. 18, the larger the value on the horizontal axis, the higher the generation efficiency of the cancellation magnetic field.

[0035] The above describes a preferred embodiment of the present invention, but the present invention is not limited to the above embodiment, and various modifications are possible within the scope of the present invention, and it goes without saying that these modifications are also included within the scope of the present invention. [Explanation of symbols]

[0036] 1 Magnetic sensor 8 PCB 10,20 External magnetic material 11,21 Main body 12,22 Protrusion 100 sensor chips 101 Element formation surface 102 Back side 103 Mounting surface 104 Top surface 105,106 Side 110 Chip body 111,112,113,114 Insulating layer 120 Compensation coil 121 Lower Pattern 122 Upper layer pattern 123 Via conductor 124,125 connection pads 131~134 Terminal electrode D1~D3 dummy elements G1~G3 magnetic gap L1, L2 wiring M1~M3 magnetic layer R, R1, R2 magnetic sensing element R10~R13 fixed resistors V1~V3 detection signal

Claims

1. first and second magnetic layers facing each other across a magnetic gap; a magnetic sensing element disposed on a magnetic path formed by the magnetic gap; a compensation coil wound around the first and second magnetic layers, the first magnetic layer, the second magnetic layer, the magnetic sensing element, and the compensation coil are integrated on a sensor chip; the sensor chip has first, second, third, and fourth layers stacked in this order; the compensation coil includes a plurality of lower layer patterns formed on the first layer and a plurality of upper layer patterns formed on the fourth layer, the magnetic sensing element is formed on the second layer, The magnetic sensor is characterized in that the first and second magnetic layers are formed on the third layer.

2. The magnetic sensor according to claim 1, characterized in that, among the multiple via conductors connecting the lower layer pattern and the upper layer pattern, two adjacent via conductors in a direction perpendicular to the extension direction of the magnetic gap are positioned at different positions in the extension direction of the magnetic gap.

3. 3. The magnetic sensor according to claim 1, wherein any one of the plurality of lower layer patterns and the plurality of upper layer patterns overlaps with the magnetic sensing element in a plan view.

4. the first and second magnetic layers have a first edge that constitutes one end in a first direction perpendicular to the extending direction of the magnetic gap and is located on the magnetic gap side, and a second edge that constitutes the other end in the first direction and is located on the opposite side of the first edge, 4. The magnetic sensor according to claim 1, wherein the edge of the compensation coil in the first direction is located at the same position as the second edge or closer to the magnetic gap than the second edge.

5. a first outer magnetic body covering the first magnetic layer; 5. The magnetic sensor according to claim 1, further comprising a second outer magnetic body covering the second magnetic layer.

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