WO2011111458A1

WO2011111458A1 - Magnetic sensor

Info

Publication number: WO2011111458A1
Application number: PCT/JP2011/052661
Authority: WO
Inventors: 真次杉原; 秀人安藤
Original assignee: アルプス電気株式会社
Priority date: 2010-03-12
Filing date: 2011-02-08
Publication date: 2011-09-15

Abstract

Disclosed is a magnetic sensor wherein elements are disposed such that amplification and magnetic shield effects due to a soft magnetic body are maintained and that an increase of element size due to extending portion of the soft magnetic body can be suppressed. In the magnetic sensor (20), each of the magnetoresistive effect elements (A, B, C, D) has a plurality of element sections (21), which are disposed in the element width direction at intervals, and a plurality of soft magnetic bodies (23, 24), which are alternately disposed with the element sections (21) in the element width direction of the element section (21). The element section (21) has a fixed magnetic layer (34) wherein the magnetization direction is fixed, and a free magnetic layer (36), which is laminated on the fixed magnetic layer (34) with a nonmagnetic layer (35) therebetween, and which changes the magnetization direction when an external magnetic field is applied. The soft magnetic bodies (23, 24) respectively have the extending portions (23a-23c, 24a-24c) that extend in the element length direction from both the ends of each element section (21). The soft magnetic bodies (23, 24) are shared by the magnetoresistive effect elements disposed adjacent to each other in the element length direction of the element section (21).

Description

Magnetic sensor

The present invention relates to a magnetic sensor using a magnetoresistive effect element.

Conventionally, a magnetic sensor using a magnetoresistive effect element has been used as a geomagnetic sensor incorporated in a portable device such as a cellular phone. As shown in FIG. 4, the geomagnetic sensor 1 includes a sensor unit 6 in which magnetoresistive elements 2, 3, 4 and 5 are bridge-connected, an input unit 7 electrically connected to the sensor unit 6, a ground unit 8, The integrated circuit 11 can include a differential amplifier 9 and an external output terminal 10. The magnetoresistive effect elements 2 and 3 and the magnetoresistive effect elements 4 and 5 are formed so that the magnetization of the pinned magnetic layer faces in the opposite direction. The magnetoresistive effect elements 2, 3, 4, and 5 vary in resistance value with respect to the strength of the magnetic field from the sensitivity axis direction. The dynamic amplifier 9 detects the voltage change and acquires magnetic change information in the sensitivity axis direction.

Such a geomagnetic sensor needs to be separated into two or three axes to detect magnetism, so it is necessary not to have sensitivity to other axes. In order to meet such a demand, a magnetic sensor has been proposed in which the amplification effect in the sensitivity axis direction and the magnetic shield effect in the direction orthogonal to the sensitivity axis are improved (see, for example, Patent Document 1).

5 (a) and 5 (b) show a configuration diagram of the magnetoresistive effect element portion in the magnetic sensor described in Patent Document 1, wherein FIG. 5 (a) is a partial plan view, and FIG. 5 (b) is the same drawing. The AA arrow directional cross-sectional view shown to (a) is shown. A plurality of element portions 12 elongated in the X direction shown in the figure and formed with an element length L1 longer than the element width W1 are arranged at predetermined intervals in the Y direction orthogonal to the X direction, and the end portions of the element portions 12 The gap is electrically connected by the connection electrode 13 to form a meander shape. An electrode portion 15 connected to the input terminal 7, the ground terminal 8, and the output extraction portion 14 is connected to one of the element portions 12 at both ends formed in a meander shape. The element unit 12 is formed by laminating an antiferromagnetic layer, a pinned magnetic layer, a nonmagnetic layer, and a free magnetic layer in this order. As shown in FIG. 5B, the magnetoresistive effect elements 2 and 3 are formed on the substrate 16, and the magnetoresistive effect elements 2 and 3 are covered with the insulating layer 17. The space between the elements 12 forming the magnetoresistive elements 2 and 3 is also filled with an insulating layer 17.

As shown in FIG. 5A, soft magnetic bodies 18 are provided between the element portions 12 forming the magnetoresistive effect elements 2 and 3 and outside the element portion 12 located on the outermost side. Although the width dimension W2 of the soft magnetic body 18 is smaller than the width dimension W1 of the element portion 12, the length dimension L2 of the soft magnetic body 18 is set to be longer than the length dimension L1 of the element portion 12. The soft magnetic body 18 includes an extending portion 18 a that extends outward from both end portions in the length direction of the element portion 12.

The soft magnetic body 18 exhibits a yoke effect with respect to an external magnetic field in a specific direction, and exhibits a shielding effect with respect to an external magnetic field in a direction different from the specific direction (a direction orthogonal to the specific direction). That is, the soft magnetic body 18 amplifies the external magnetic field in the sensitivity axis direction (arrow Y direction) and shields the external magnetic field in the direction orthogonal to the sensitivity axis direction (arrow X direction).

International Publication No. 2009/084434 Pamphlet

However, in order to sufficiently obtain the amplification and magnetic shielding effect by the soft magnetic body 18, it can be considered that the length of the soft magnetic body 18 is greatly increased as shown in FIG. If this becomes larger, there arises a problem that the element size increases.

FIG. 7 is a diagram showing a state where four magnetoresistive elements shown in FIG. 6 are arranged and wired. For example, if it corresponds to the bridge wiring shown in FIG. 4, the elements A and D are the magnetoresistive elements 2 and 3, and the elements B and C have the magnetization of the fixed magnetic layer opposite to that of the magnetoresistive elements 2 and 3. The magnetoresistive effect elements 4 and 5 face the direction. Even an element having the same configuration as the magnetoresistive effect elements 2 and 3 can function as a bridge circuit by adjusting the sensitivity axis direction.

As described above, in order to obtain the amplification and magnetic shielding effect by the soft magnetic material, the magnetoresistive effect elements A, B, C, and D, in which the extending portion of the soft magnetic material is greatly extended, are to be arranged in the two-dimensional space. Then, there is a problem that the element size is significantly increased.

The present invention has been made in view of such points, and has an element arrangement capable of maintaining the amplification and magnetic shielding effect by the soft magnetic material and suppressing the increase of the elements due to the extending portion of the soft magnetic material. An object is to provide a realized magnetic sensor.

The magnetic sensor of the present invention is a magnetic sensor including a plurality of magnetoresistive effect elements, wherein each of the magnetoresistive effect elements includes a plurality of element portions arranged at intervals in the element width direction, and the element portions. A plurality of soft magnetic bodies arranged alternately with the element portion in the element width direction, wherein the element portion includes a pinned magnetic layer whose magnetization direction is fixed, and a nonmagnetic layer interposed between the pinned magnetic layer and the element portion. And a free magnetic layer whose magnetization direction is changed by receiving an external magnetic field, and the soft magnetic body has extension portions extending in the element length direction from both ends in the length direction of the element portion, respectively. And the soft magnetic material is shared between the magnetoresistive elements arranged adjacent to each other in the element length direction of the element section.

According to this configuration, by sharing the soft magnetic material between the magnetoresistive effect elements, the soft magnetic material arranged for each element unit is at least the total of the two element units connected in the element length direction. Since the length is longer than the length, the amplification and magnetic shielding effect by the soft magnetic material can be greatly improved. This means that if the soft magnetic material amplification and magnetic shielding effect are maintained, the length of the extension portion of the soft magnetic material between the elements sharing the soft magnetic material can be shortened to increase the distance between the devices. It means that it can be shortened. Therefore, it is possible to maintain the amplification and magnetic shield effect by the soft magnetic material and to reduce the element size by shortening the distance between the elements.

According to the present invention, in the magnetic sensor, the extension portion of the soft magnetic body includes an inner extension portion that extends to a side facing the counterpart element that shares the soft magnetic body, and a side that does not face the counterpart element. And an outer extension portion extending to the inner extension portion, wherein the inner extension portion has a smaller extension amount than the outer extension portion.

With this configuration, it is possible to suppress an increase in the element size by maintaining the amplification and magnetic shielding effect by the soft magnetic material and shortening the distance between the elements.

In the magnetic sensor, the plurality of element portions are formed in a meander shape by alternately connecting ends of adjacent element portions, and the plurality of element portions and the plurality of soft magnetic bodies are formed differently. It may be formed on the surface.

According to the present invention, it is possible to realize an element arrangement capable of maintaining the amplification and the magnetic shielding effect by the soft magnetic material and suppressing the increase of elements due to the extended portion of the soft magnetic material.

It is a top view which shows element arrangement | positioning of the magnetic sensor which concerns on embodiment of this invention. It is sectional drawing of the element part in embodiment. It is a top view which shows element arrangement | positioning of the magnetic sensor which concerns on a modification. It is a circuit block diagram of a geomagnetic sensor. 2 is a configuration diagram of a magnetoresistive effect element portion in a magnetic sensor described in Patent Document 1. FIG. It is a top view of the magnetoresistive effect element which extended the extension part of the soft-magnetic body. It is a figure which shows a mode that four magnetoresistive effect elements shown in FIG. 6 are arrange | positioned and wired.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.
In the embodiment of the present invention, a soft magnetic material is shared between a plurality of magnetoresistive elements arranged continuously in the element length direction of the element portion, and the length of the soft magnetic material extending portion between adjacent elements is It has a configuration with a reduced size. Here, an example of a four-element arrangement will be described, but the number of elements and the arrangement configuration are not limited to this. Hereinafter, an embodiment applied to the geomagnetic sensor 1 shown in FIG. 4 will be described.

FIG. 1 is a plan view showing an element arrangement of a sensor unit of a magnetic sensor according to an embodiment of the present invention. The magnetic sensor 20 according to the present embodiment forms a sensor unit by four magnetoresistive elements A, B, C, and D that are bridge-connected. Two magnetoresistive elements A and B are disposed adjacent to each other in the X direction, and the remaining two magnetoresistive elements C and D are disposed adjacent to each other in the X direction. The magnetoresistive effect element A and the magnetoresistive effect element C are adjacent to each other in the Y direction, and the magnetoresistive effect element B and the magnetoresistive effect element D are adjacent to each other in the Y direction. A soft magnetic material is shared between the two magnetoresistive elements A and B arranged adjacent to each other in the X direction, and a soft magnetic material is shared between the two magnetoresistive elements C and D. Here, common means that a strip of soft magnetic material penetrates between magnetoresistive elements A and B.

The four magnetoresistive elements A, B, C, and D have the same basic configuration as the magnetoresistive element 12 (13) shown in FIGS. 4 and 5 except that a soft magnetic material is used in common. . Each of the magnetoresistive effect elements A, B, C, and D has a plurality of element portions 21 that are formed in an element length (L1) longer than the element width (W1) and are elongated in the X direction in the figure, and are spaced at a predetermined interval in the Y direction. Arranged at intervals, the end portions of the element portions 21 are electrically connected by the connection electrodes 22 to form a meander shape. In the magnetoresistive effect elements A and C, an electrode 22 a connected to the input terminal 7 (FIG. 4) is formed on one of the element parts 21 at both ends formed in a meander shape, and an output extraction part is formed on the other of the element parts 12. 14 is connected to the electrode portion 22b. In the magnetoresistive effect elements B and D, an electrode 22c connected to the ground terminal 8 (FIG. 4) is formed on one of the element portions 21 at both ends formed in a meander shape, and output to the other of the element portions 21. An electrode portion 22d connected to the extraction portion 14 (FIG. 4) is connected.

On the other hand, soft

magnetic bodies

23 and 24 are provided between the element portions 21 in each of the magnetoresistive effect elements A, B, C, and D and outside the element portion 21 located on the outermost side. A soft magnetic body 23 is shared between two magnetoresistive elements A and B arranged adjacent to each other in the X direction, and between two magnetoresistive elements C and D arranged adjacent to each other in the X direction. The soft magnetic body 24 is shared. The soft

magnetic bodies

23 and 24 have first outer extending portions 23a and 24a that extend largely outward from one end (upper side in the figure) of the element portion 21 of the magnetoresistive effect elements A and C in the X direction. Similarly, it has second outer extending portions 23b and 24b that greatly extend outward from the other end (lower side in the figure) of the element portion 21 in the X direction. Further, the soft magnetic body 23 (24) slightly extends outside the end portion of the element portion 21 between the magnetoresistive effect elements A and B (C, D) (the opposing direction of the elements A and B). Inner extending

portions

23c and 24c are provided. The

inner extension portions

23c and 24c are greatly reduced in length as compared with the first (second) outer extension portions 23a and 24a (23b and 24b). The length dimensions of the first and second outer extending portions 23a, 24a, 23b, and 24b are such that, for example, the required amplification and magnetic shielding effects can be obtained as in the soft magnetic material extending portion shown in FIG. It is long.

Further, the magnetoresistive effect elements A, B, C, and D have a cross-sectional structure similar to the structure shown in FIG. That is, the magnetoresistive elements A, B, C, and D are formed on the substrate 16 (FIG. 5B), and the magnetoresistive elements A, B, C, and D are covered with the insulating layer 17. The space between the elements 12 forming the magnetoresistive effect elements A, B, C, D is also filled with an insulating layer 17. A soft magnetic material 23 (24) is formed on the insulating layer 17.

Each magnetoresistive effect element A, B, C, D is constituted by the same laminated structure. FIG. 2 is a view showing a laminated structure of the magnetoresistive effect element A, and shows a cut surface cut in the film thickness maintaining direction from a direction parallel to the element width of the element portion 21. The element unit 21 is formed by laminating an antiferromagnetic layer 33, a pinned magnetic layer 34, a nonmagnetic layer 35, and a free magnetic layer 36 in this order from below, and the surface of the free magnetic layer 36 is covered with a protective layer 37. Yes. The element part 21 can be formed by sputtering.

The antiferromagnetic layer 33 is made of an antiferromagnetic material such as an Ir-Mn alloy (iridium-manganese alloy). The pinned magnetic layer 34 is formed of a soft magnetic material such as Co—Fe (cobalt-iron alloy). The nonmagnetic layer 35 is made of Cu (copper) or the like. The free magnetic layer 36 is formed of a nonmagnetic material such as a Ni—Fe alloy (nickel-iron alloy). The protective layer 37 is made of Ta (tantalum) or the like. In this embodiment, the non-magnetic layer 35, but is a non-magnetic conductive material giant magnetoresistance effect element formed by such Cu (GMR element), a tunnel magnetoresistive formed of insulating material such as Al ₂ O ₃ It may be a resistance effect element (TRM element). Moreover, the laminated structure of the element part 21 is an example, and another laminated structure can also be employ | adopted. For example, the free magnetic layer 36, the nonmagnetic layer 35, the pinned magnetic layer 34, the antiferromagnetic layer 33, and the protective layer 37 may be stacked in this order from the bottom.

In the element portion 21, the magnetization direction of the pinned magnetic layer 34 is fixed by antiferromagnetic coupling between the antiferromagnetic layer 33 and the pinned magnetic layer 34. As shown in FIG. 2, the pinned magnetization direction P of the pinned magnetic layer 34 faces the element width direction (Y direction). That is, the fixed magnetization direction P of the fixed magnetic layer 34 is orthogonal to the longitudinal direction (X direction) of the element portion 21. On the other hand, the magnetization direction F of the free magnetic layer 36 varies depending on the external magnetic field. When an external magnetic field acts from the same direction as the fixed magnetization direction P of the fixed magnetic layer 34 and the magnetization direction F of the free magnetic layer 36 is directed to the external magnetic field direction, the fixed magnetization direction P of the fixed magnetic layer 34 and the free magnetic layer 36 As the magnetization direction F approaches parallel, the electrical resistance value decreases. Conversely, when an external magnetic field acts from a direction opposite to the fixed magnetization direction P of the fixed magnetic layer 34 and the magnetization direction F of the free magnetic layer 36 is directed to the external magnetic field direction, the electrical resistance value increases.

According to the present embodiment configured as described above, between the magnetoresistive effect elements A and B and between the magnetoresistive effect elements C and D arranged adjacent to each other in the X direction which is the longitudinal direction of the element portion 21. The common use of the soft

magnetic bodies

23 and 24 makes the length of the soft

magnetic bodies

23 and 24 for one element significantly longer than the configuration in which an independent soft magnetic body is provided for each element. The effect of amplifying the external magnetic field in the direction (Y direction) is increased, and the shielding effect against the external magnetic field in the direction (X direction) orthogonal to the sensitivity axis direction is also increased. Therefore, even if the length dimension of the inner extending

portions

23c, 24c is greatly shortened between the elements (A, B), (C, D) where the soft

magnetic bodies

23, 24 are shared, the soft

magnetic bodies

23, 24 can maintain the amplification and magnetic shielding effect, and the increase in the element size as a whole can be suppressed.

Fig. 3 shows a variation of the 4-element arrangement. The magnetic sensor 40 shown in FIG. 3 constitutes a sensor unit with four magnetoresistive elements A, B, C, and D that are bridge-connected. The four magnetoresistive elements A, B, C, and D share a soft magnetic material. Magnetoresistive elements A and D are arranged on both sides in the X direction, and two magnetoresistive elements B and C are arranged in parallel between them. The sensor region of the magnetoresistive effect elements B and C arranged in parallel in the Y direction (the region where the element portion 21 is formed) has a dimension in the width direction perpendicular to the longitudinal direction of the element portion 21 and the magnetoresistive effect element A , D are less than half of the dimension in the width direction in the same direction. That is, if the magnetoresistive effect elements A and D have the same structure as the magnetoresistive effect element shown in FIG. 1, ten element parts 21 are arranged at predetermined intervals in the sensor part region of the magnetoresistive effect elements A and D. However, in this modification, the magnetoresistive elements B and C arranged in the middle have five element portions 21 arranged at predetermined intervals. The five element portions 21 of the magnetoresistive effect elements B and C are approximately twice as long as the element portion 21 of the magnetoresistive effect elements A and D.

The common soft magnetic body 41 has a length larger than the interval between the magnetoresistive effect element A disposed at one end in the X direction and the magnetoresistive effect element D disposed at the other end in the X direction as described above. Have dimensions. That is, the soft magnetic body 41 has a length that penetrates the magnetoresistive effect elements A, B, C, and D in the X direction, and is larger outward than one end of the element portion 21 of the magnetoresistive effect element A in the X direction. A first outer extension portion 41a that extends and a second outer extension portion 41b that extends to the outside of the other end in the X direction of the element portion 21 of the magnetoresistive element D disposed on the opposite side. And have. The soft magnetic body 41 includes the other end (lower side in the figure) of the element portion 21 (10 pieces) of the magnetoresistive effect element A and the element portions 21 (5 pieces each) of the magnetoresistive effect elements B and C. The first inner extending portion 41c slightly extending to a portion facing the one end in the X direction (upper side in the figure), and one end in the X direction (10 pieces) of the element portions 21 (10 pieces) of the magnetoresistive effect element D The second inner extending portion 41d that slightly extends to a portion facing the other end in the X direction (the lower side in the figure) of the element portions 21 (five each) of the magnetoresistive effect elements B and C (middle upper side). And having. The first and second outer extending

portions

41a and 41b are formed sufficiently longer than the length of the first and second inner extending

portions

41c and 41d. The magnetoresistive elements A, B, C, and D have the same basic element structure as the magnetic sensor of the above embodiment except for the common configuration of the soft magnetic body 41.

According to such a modified example, there are two outer extending portions (first and second outer extending

portions

41a and 41b) that greatly extend from the end of the element portion 21 to the outside. In addition, the element size can be further reduced as compared with the above-described embodiment in which the second outer extending portions 23a, 23b, 24a, and 24b are four places. In each of the magnetoresistive elements A, B, C, and D, the length of the soft magnetic body 41 with respect to one element is significantly increased, and the effect of amplifying the external magnetic field in the sensitivity axis direction (Y direction) is increased. In addition, the shielding effect against the external magnetic field in the direction (X direction) orthogonal to the sensitivity axis direction is also increased.

The present invention is applicable to a magnetic sensor using a plurality of magnetoresistive elements such as a geomagnetic sensor.

This application is based on Japanese Patent Application No. 2010-056151 filed on Mar. 12, 2010. All this content is included here.

Claims

A magnetic sensor comprising a plurality of magnetoresistive elements,
Each of the magnetoresistive elements has a plurality of element portions arranged at intervals in the element width direction and a plurality of soft magnetic bodies arranged alternately with the element portions in the element width direction of the element portion. And
The element portion includes a pinned magnetic layer whose magnetization direction is fixed, and a free magnetic layer that is stacked on the pinned magnetic layer via a nonmagnetic layer and receives an external magnetic field and changes the magnetization direction.
The soft magnetic body has extending portions extending in the element length direction from both ends in the length direction of the element portion,
A magnetic sensor characterized in that the soft magnetic material is shared between magnetoresistive elements arranged adjacent to each other in the element length direction of the element section.
The extension part of the soft magnetic body includes an inner extension part that extends to the side facing the counterpart element that shares the soft magnetic body, and an outer extension part that extends to the side not facing the counterpart element. The magnetic sensor according to claim 1, wherein the inner extension portion has a smaller extension amount than the outer extension portion.
The plurality of element portions have a meander shape in which the ends of adjacent element portions are alternately connected,
The magnetic sensor according to claim 1, wherein the plurality of element portions and the plurality of soft magnetic bodies are formed on different formation surfaces.