Magnetic sensor

A magnetic sensor includes a substrate including a top surface, an insulating layer including an inclined surface, an MR element disposed on the inclined surface, a first insulating portion of an insulating material disposed on a part of the MR element, and a second insulating portion of an insulating material disposed on another part of the MR element at a position forward of the first insulating portion in a direction along the inclined surface, the direction being a direction away from the top surface of the substrate.

BACKGROUND

The technology relates to a magnetic sensor including magnetoresistive elements each disposed on an inclined surface.

Magnetic sensors using magnetoresistive elements have been used for various applications in recent years. A system including a magnetic sensor may be intended to detect a magnetic field containing a component in a direction perpendicular to the surface of a substrate by using a magnetoresistive element provided on the substrate. In such a case, the magnetic field containing the component in the direction perpendicular to the surface of the substrate can be detected by providing a soft magnetic body for converting a magnetic field in the direction perpendicular to the surface of the substrate into a magnetic field in the direction parallel to the surface of the substrate or locating the magnetoresistive element on an inclined surface formed on the substrate.

As the magnetoresistive elements, spin-valve magnetoresistive elements are used, for example. The spin-valve magnetoresistive element includes a magnetization pinned layer having a magnetization whose direction is fixed, a free layer having a magnetization whose direction is variable depending on the direction of an applied magnetic field, and a gap layer disposed between the magnetization pinned layer and the free layer.

U.S. Patent Application Publication No. 2006/0176142 A1 discloses a magnetic sensor including magnetoresistive elements each formed on an inclined surface. Japanese Patent Application Laid-Open Publication No. 2008-141210 discloses a technique of forming two protective films of different materials on each side surface of a magnetoresistive element, thereby reducing a stress applied to the magnetoresistive element.

Typically, in a case where a magnetoresistive element is formed on an inclined surface as in the magnetic sensor disclosed in U.S. Patent Application Publication No. 2006/0176142 A1, side surfaces of the magnetoresistive element are tapered. Herein, regarding a case where a spin-valve magnetoresistive element is used as a magnetoresistive element, suppose a case where the characteristics of the magnetoresistive element are controlled using an insulating layer formed around the magnetoresistive element as in the technique disclosed in Japanese Patent Application Laid-Open Publication No. 2008-141210. A first layer located close to the inclined surface and a second layer located away from the inclined surface have different areas. Therefore, influence of the insulating layer on the first layer and influence of the insulating layer on the second layer are also different. Consequently, the magnetoresistive element may undesirably have characteristics different from the intended ones.

SUMMARY

A magnetic sensor according to one embodiment of the technology includes a substrate including a reference plane; a support member disposed on the substrate, the support member including at least one inclined surface inclined with respect to the reference plane; at least one magnetic detection element disposed on the at least one inclined surface; a first insulating portion of an insulating material disposed on a part of the at least one magnetic detection element; and a second insulating portion of an insulating material disposed on another part of the at least one magnetic detection element at a position forward of the first insulating portion in a direction along the at least one inclined surface, the direction being a direction away from the reference plane.

In the magnetic sensor according to one embodiment of the technology, the first insulating portion is disposed on a part of the magnetic detection element disposed on the inclined surface, and the second insulating portion is disposed on another part of the magnetic detection element. Thereby according to one embodiment of the technology, it is possible to achieve desired characteristics for a magnetic sensor including magnetoresistive elements each disposed on an inclined surface.

Other and further objects, features, and advantages of the technology will appear more fully from the following description.

DETAILED DESCRIPTION

An object of the technology is to provide a magnetic sensor that includes magnetoresistive elements each disposed on an inclined surface and in which desired characteristics can be achieved.

In the following, some example embodiments and modification examples of the technology are described in detail with reference to the accompanying drawings. Note that the following description is directed to illustrative examples of the disclosure and not to be construed as limiting the technology. Factors including, without limitation, numerical values, shapes, materials, components, positions of the components, and how the components are coupled to each other are illustrative only and not to be construed as limiting the technology. Further, elements in the following example embodiments which are not recited in a most-generic independent claim of the disclosure are optional and may be provided on an as-needed basis. The drawings are schematic and are not intended to be drawn to scale. Like elements are denoted with the same reference numerals to avoid redundant descriptions. Note that the description is given in the following order.

First Example Embodiment

First, a configuration of a magnetic sensor according to a first example embodiment of the technology will be described with reference toFIGS.1and2.FIG.1is a perspective view showing a magnetic sensor according to the example embodiment.FIG.2is a functional block diagram showing a configuration of a magnetic sensor device including the magnetic sensor according to the example embodiment.

As shown inFIG.1, the magnetic sensor1is in the form of a chip having a rectangular parallelepiped shape. The magnetic sensor1includes a top surface1aand a bottom surface located opposite to each other and also includes four side surfaces connecting the top surface1ato the bottom surface. The magnetic sensor1also includes a plurality of electrode pads disposed on the top surface1a.

Now, a description will be given of a reference coordinate system in the present example embodiment with reference toFIG.1. The reference coordinate system is an orthogonal coordinate system that is set with reference to a magnetic sensor1and defined by three axes. An X direction, a Y direction, and a Z direction are defined in the reference coordinate system. The X, Y, and Z directions are orthogonal to each other. In particular, in the example embodiment, a direction that is perpendicular to the top surface1aof the magnetic sensor1and is oriented from the bottom surface to the top surface1aof the magnetic sensor1is defined as the Z direction. The opposite directions to the X, Y, and Z directions will be expressed as −X, −Y, and −Z directions, respectively. The three axes defining the reference coordinate system are an axis parallel to the X direction, an axis parallel to the Y direction, and an axis parallel to the Z direction.

Hereinafter, the term “above” refers to positions located forward of a reference position in the Z direction, and “below” refers to positions opposite from the “above” positions with respect to the reference position. For each component of the magnetic sensor1, the term “top surface” refers to a surface of the component located at the end thereof in the Z direction, and “bottom surface” refers to a surface of the component located at the end thereof in the −Z direction. The phrase “when seen in the Z direction” means that an object is seen from a position at a distance in the Z direction.

As shown inFIG.2, the magnetic sensor1includes a first detection circuit20and a second detection circuit30. Each of the first and second detection circuits20and30includes a plurality of magnetic detection elements, and is configured to detect a target magnetic field to generate at least one detection signal. In particular, in the example embodiment, the plurality of magnetic detection elements are a plurality of magnetoresistive elements. The magnetoresistive elements will hereinafter be referred to as MR elements.

A plurality of detection signals generated by the first and second detection circuits20and30are processed by a processor40. The magnetic sensor1and the processor40constitute a magnetic sensor device100. The processor40is configured to, by processing the plurality of detection signals generated by the first and second detection circuits20and30, generate a first detection value and a second detection value respectively having correspondences with components of a magnetic field in two different directions at a predetermined reference position. In particular, in the present example embodiment, the foregoing two different directions are a direction parallel to an XY plane and a direction parallel to the Z direction. For example, the processor40is constructed of an application-specific integrated circuit (ASIC).

The processor40may be included in a support supporting the magnetic sensor1, for example. The support includes a plurality of electrode pads. The first and second detection circuits20and30are connected to the processor40via the plurality of electrode pads of the magnetic sensor1, the plurality of electrode pads of the support, and a plurality of bonding wires, for example. In a case where the plurality of electrode pads of the magnetic sensor1are provided on the top surface1aof the magnetic sensor1, the magnetic sensor1may be mounted on the top surface of the support in such a posture that the bottom surface of the magnetic sensor1faces the top surface of the support.

Next, the first and second detection circuits20and30will be described with reference toFIGS.3to6.FIG.3is a circuit diagram showing a circuit configuration of the first detection circuit20.FIG.4is a circuit diagram showing a circuit configuration of the second detection circuit30.FIG.5is a plan view showing a part of the magnetic sensor1.FIG.6is a sectional view showing a part of the magnetic sensor1.

Here, as shown inFIG.5, a U direction and a V direction are defined as follows. The U direction is a direction rotated from the X direction to the −Y direction. The V direction is a direction rotated from the Y direction to the X direction. More specifically, in the present example embodiment, the U direction is set to a direction rotated from the X direction to the −Y direction by α, and the V direction is set to a direction rotated from the Y direction to the X direction by α. Note that α is an angle greater than 0° and smaller than 90°. For example, α is 45°. −U direction refers to a direction opposite to the U direction, and −V direction refers to a direction opposite to the V direction.

As shown inFIG.6, a W1direction and a W2direction are defined as follows. The W1direction is a direction rotated from the V direction to the −Z direction. The W2direction is a direction rotated from the V direction to the Z direction. More specifically, in the present example embodiment, the W1direction is set to a direction rotated from the V direction to the −Z direction by β, and the W2direction is set to a direction rotated from the V direction to the Z direction by β. Note that β is an angle greater than 0° and smaller than 90°. −W1direction refers to a direction opposite to the W1direction, and −W2direction refers to a direction opposite to the W2direction. The W1direction and W2direction both are orthogonal to the U direction.

The first detection circuit20is configured to detect a component of the target magnetic field in a direction parallel to the W1direction and generate at least one first detection signal which has a correspondence with the component. The second detection circuit30is configured to detect a component of the target magnetic field in a direction parallel to the W2direction and generate at least one second detection signal which has a correspondence with the component.

As shown inFIG.3, the first detection circuit20includes a power supply port V2, a ground port G2, signal output ports E21and E22, a first resistor section R21, a second resistor section R22, a third resistor section R23, and a fourth resistor section R24. The plurality of MR elements of the first detection circuit20constitute the first to fourth resistor sections R21, R22, R23, and R24.

The first resistor section R21is provided between the power supply port V2and the signal output port E21. The second resistor section R22is provided between the signal output port E21and the ground port G2. The third resistor section R23is provided between the signal output port E22and the ground port G2. The fourth resistor section R24is provided between the power supply port V2and the signal output port E22.

As shown inFIG.4, the second detection circuit30includes a power supply port V3, a ground port G3, signal output ports E31and E32, a first resistor section R31, a second resistor section R32, a third resistor section R33, and a fourth resistor section R34. The plurality of MR elements of the second detection circuit30constitute the first to fourth resistor sections R31, R32, R33, and R34.

The first resistor section R31is provided between the power supply port V3and the signal output port E31. The second resistor section R32is provided between the signal output port E31and the ground port G3. The third resistor section R33is provided between the signal output port E32and the ground port G3. The fourth resistor section R34is provided between the power supply port V3and the signal output port E32.

A voltage or current of a predetermined magnitude is applied to each of the power supply ports V2and V3. Each of the ground ports G2and G3is connected to the ground.

The plurality of MR elements of the first detection circuit20will be referred to as a plurality of first MR elements50B. The plurality of MR elements of the second detection circuit30will be referred to as a plurality of second MR elements50C. Since the first and second detection circuits20and30are the components of the magnetic sensor1, it can be said that the magnetic sensor1includes the plurality of first MR elements50B and the plurality of second MR elements50C. Any given MR element will be denoted by the reference numeral50.

FIG.7is a side view showing the MR element50. The MR element50is a spin-valve MR element including a plurality of magnetic layers. The MR element50includes a magnetization pinned layer51having a magnetization whose direction is fixed, a free layer53having a magnetization whose direction is variable depending on the direction of a target magnetic field, and a gap layer52located between the magnetization pinned layer51and the free layer53. The MR element50may be a tunneling magnetoresistive (TMR) element or a giant magnetoresistive (GMR) element. In the TMR element, the gap layer52is a tunnel barrier layer. In the GMR element, the gap layer52is a nonmagnetic conductive layer. The resistance of the MR element50changes with the angle that the magnetization direction of the free layer53forms with respect to the magnetization direction of the magnetization pinned layer51. The resistance of the MR element50is at its minimum value when the foregoing angle is 0°, and at its maximum value when the foregoing angle is 180°. In each MR element50, the free layer53has a shape anisotropy that sets the direction of the magnetization easy axis to be orthogonal to the magnetization direction of the magnetization pinned layer51. As a method for setting the magnetization easy axis in a predetermined direction in the free layer53, a magnet configured to apply a bias magnetic field to the free layer53can be used. The magnetization pinned layer51, the gap layer52, and the free layer53are stacked in this order.

The MR element50may further include an antiferromagnetic layer disposed on the magnetization pinned layer51on the side opposite to the gap layer52. The antiferromagnetic layer is formed of an antiferromagnetic material, and is in exchange coupling with the magnetization pinned layer51to thereby pin the magnetization direction of the magnetization pinned layer51. Alternatively, the magnetization pinned layer51may be a so-called self-pinned layer (Synthetic Ferri Pinned layer, SFP layer). The self-pinned layer has a stacked ferri structure in which a ferromagnetic layer, a nonmagnetic intermediate layer, and a ferromagnetic layer are stacked, and the two ferromagnetic layers are antiferromagnetically coupled.

It should be appreciated that the layers51to53of each MR element50may be stacked in the reverse order to that shown inFIG.7.

InFIGS.3and4, solid arrows represent the magnetization directions of the magnetization pinned layers51of the MR elements50. Hollow arrows represent the magnetization directions of the free layers53of the MR elements50in a case where no target magnetic field is applied to the MR elements50.

In the example shown inFIG.3, the magnetization directions of the magnetization pinned layers51in each of the first and third resistor sections R21and R23are the W1direction. The magnetization directions of the magnetization pinned layers51in each of the second and fourth resistor sections R22and R24are the −W1direction. The free layer53in each of the plurality of first MR elements50B has a shape anisotropy that sets the direction of the magnetization easy axis to a direction parallel to the U direction. The magnetization directions of the free layers53in each of the first and second resistor sections R21and R22in a case where no target magnetic field is applied to the first MR elements50B are the U direction. The magnetization directions of the free layers53in each of the third and fourth resistor sections R23and R24in the foregoing case are the −U direction.

In the example shown inFIG.4, the magnetization directions of the magnetization pinned layers51in each of the first and third resistor sections R31and R33are the W2direction. The magnetization directions of the magnetization pinned layers51in each of the second and fourth resistor sections R32and R34are the −W2direction. The free layer53in each of the plurality of second MR elements50C has a shape anisotropy that sets the direction of the magnetization easy axis to a direction parallel to the U direction. The magnetization directions of the free layers53in each of the first and second resistor sections R31and R32in a case where no target magnetic field is applied to the second MR elements50C are the U direction. The magnetization directions of the free layers53in each of the third and fourth resistor sections R33and R34in the foregoing case are the −U direction.

The magnetic sensor1includes a magnetic field generator configured to apply a magnetic field in a predetermined direction to the free layer53of each of the plurality of first MR elements50B, and the plurality of second MR elements50C. In the present example embodiment, the magnetic field generator includes a coil80that applies a magnetic field in the predetermined direction to the free layer53in each of the plurality of first MR elements50B and the plurality of second MR elements50C.

Note that the magnetization directions of the magnetization pinned layers51and the directions of the magnetization easy axes of the free layers53may slightly deviate from the foregoing directions from the perspective of the accuracy of the manufacturing of the MR elements50and the like. The magnetization pinned layers51may be magnetized to include magnetization components in the foregoing directions as their main components. In such a case, the magnetization directions of the magnetization pinned layers51are the same or substantially the same as the foregoing directions.

In the present example embodiment, the MR element50is configured such that a current flows in the stacking direction of the plurality of magnetic layers, that is, the magnetization pinned layer51and the free layer53. As described below, the magnetic sensor1includes a lower electrode and an upper electrode for flowing a current through the MR element50. The MR element50is disposed between the lower electrode and the upper electrode.

Hereinafter, a specific structure of the magnetic sensor1will be described in detail with reference toFIGS.5and6.FIG.6shows a part of a cross section at a position indicated by the line6-6inFIG.5.

The magnetic sensor1includes a substrate301with a top surface301a, insulating layers302,303,304,305,306,307,308,309, and310, a plurality of lower electrodes61B, a plurality of lower electrodes61C, a plurality of upper electrodes62B, a plurality of upper electrodes62C, a plurality of lower coil elements81, and a plurality of upper coil elements82. It is assumed that the top surface301aof the substrate301is parallel to the XY plane. The Z direction is also a direction perpendicular to the top surface301aof the substrate301. The coil elements are a part of the coil winding.

The insulating layer302is disposed on the substrate301. The plurality of lower coil elements81are disposed on the insulating layer302. The insulating layer303is disposed around the plurality of lower coil elements81on the insulating layer302. The insulating layers304and305are stacked in this order on the plurality of lower coil elements81and the insulating layer303.

The plurality of lower electrodes61B and the plurality of lower electrodes61C are disposed on the insulating layer305. The plurality of first MR elements50B are disposed on the plurality of lower electrodes61B. The plurality of second MR elements50C are disposed on the plurality of lower electrodes61C. The insulating layer306is disposed on the plurality of lower electrodes61B and the plurality of lower electrodes61C and around the plurality of first MR elements50B and around the plurality of second MR elements50C. The insulating layer307is disposed on the insulating layer305and around the plurality of lower electrodes61B, around the plurality of lower electrodes61C, and around the insulating layer306.

The insulating layer308is disposed on a part of each of the plurality of first MR elements50B, on a part of each of the plurality of second MR elements50C, and on the insulating layers306and307. The plurality of upper electrodes62B are disposed on another part of each of the plurality of first MR elements50B and on a part of the insulating layer308. The plurality of upper electrodes62C are disposed on another part of each of the plurality of second MR elements50C and on a part of the insulating layer308. The insulating layer309is disposed on another part of the insulating layer308and around the plurality of upper electrodes62B and around the plurality of upper electrodes62C.

The insulating layer310is disposed on the plurality of upper electrodes62B, the plurality of upper electrodes62C, and the insulating layer309. The plurality of upper coil elements82are disposed on the insulating layer310. The magnetic sensor1may further include a not-shown insulating layer that covers the plurality of upper coil elements82and the insulating layer310.

The magnetic sensor1includes a support member supporting the plurality of first MR elements50B and the plurality of second MR elements50C. The support member includes at least one inclined surface inclined with respect to the top surface301aof the substrate301. In particular, in the example embodiment, the support member includes the insulating layer305. Note thatFIG.5shows the insulating layer305, the plurality of first MR elements50B, the plurality of second MR elements50C, and the plurality of upper coil elements82among the components of the magnetic sensor1.

The insulating layer305includes a plurality of protruding surfaces305ceach protruding in a direction (the Z direction) away from the top surface301aof the substrate301. Each of the plurality of protruding surfaces305cextends in a direction parallel to the U direction. The overall shape of each of the protruding surfaces305cis a semi-cylindrical curved surface formed by moving the curved shape (arch shape) of the protruding surface305cshown inFIG.6along the direction parallel to the U direction. The plurality of protruding surfaces305care arranged at predetermined intervals along a direction parallel to the V direction.

Each of the plurality of protruding surfaces305cincludes an upper end portion farthest from the top surface301aof the substrate301. In the example embodiment, each of the upper end portions of the plurality of protruding surfaces305cextends in the direction parallel to the U direction. Herein, focus is placed on a given protruding surface305cof the plurality of protruding surfaces305c. The protruding surface305cincludes a first inclined surface305aand a second inclined surface305b. The first inclined surface305arefers to the part of the protruding surface305con the side of the V direction of the upper end portion of the protruding surface305c. The second inclined surface305brefers to the part of the protruding surface305con the side of the −V direction of the upper end portion of the protruding surface305c. InFIG.5, a boundary between the first inclined surface305aand the second inclined surface305bis indicated by a dotted line.

The upper end portion of the protruding surface305cmay be the boundary between the first inclined surface305aand the second inclined surface305b. In such a case, the dotted line shown inFIG.5indicates the upper end portion of the protruding surface305c.

The top surface301aof the substrate301is parallel to the XY plane. Each of the first inclined surface305aand the second inclined surface305bis inclined with respect to the top surface301aof the substrate301, that is, the XY plane. In a cross section perpendicular to the top surface301aof the substrate301, a distance between the first inclined surface305aand the second inclined surface305bbecomes smaller in a direction away from the top surface301aof the substrate301.

In the example embodiment, since two or more protruding surface305care present, the number of each of the first inclined surfaces305aand the second inclined surfaces305bis also two or more. The insulating layer305includes the plurality of first inclined surfaces305aand the plurality of second inclined surfaces305b.

The insulating layer305further includes a flat surface305dpresent around the plurality of protruding surfaces305c. The flat surface305dis a surface parallel to the top surface301aof the substrate301. Each of the plurality of protruding surfaces305cprotrudes in the Z direction from the flat surface305d. In the example embodiment, the plurality of protruding surfaces305care disposed at predetermined intervals. Thus, the flat surface305dis present between the two protruding surfaces305cadjoining in the V direction.

The insulating layer305includes a plurality of protruding portions each protruding in the Z direction, and a flat portion present around the plurality of protruding portions. Each of the plurality of protruding portions extends in the direction parallel to the U direction and includes the protruding surface305c. The plurality of protruding portions are arranged at predetermined intervals in the direction parallel to the V direction. The thickness (the dimension in the Z direction) of the flat portion is substantially constant. The insulating layer304has a substantially constant thickness (i.e., a dimension in the Z direction), and is formed along the bottom surface of the insulating layer305.

The plurality of lower electrodes61B are disposed on the plurality of first inclined surfaces305a. The plurality of lower electrodes61C are disposed on the plurality of second inclined surfaces305b. As described above, since each of the first inclined surfaces305aand the second inclined surfaces305bis inclined with respect to the top surface301aof the substrate301, that is, the XY plane, each of the top surfaces of the plurality of lower electrodes61B and each of the top surfaces of the plurality of lower electrodes61C are also inclined with respect to the XY plane. Thus, it can be said that the plurality of first MR elements50B and the plurality of second MR elements50C are disposed on the inclined surfaces inclined with respect to the XY plane. The insulating layer305is a member for supporting each of the plurality of first MR elements50B and the plurality of second MR elements50C so as to allow such MR elements to be inclined with respect to the XY plane.

Note that in the example embodiment, the first inclined surfaces305aare curved surfaces. Therefore, the first MR elements50B are curved along the curved surfaces (the first inclined surfaces305a). For the sake of convenience, in the present example embodiment, the magnetization directions of the magnetization pinned layers51of the first MR elements50B are defined as straight directions as described above. The W1direction and the −W1direction that are the magnetization directions of the magnetization pinned layers51of the first MR elements50B are also directions in which the tangents to the first inclined surfaces305aat the vicinity of the first MR elements50B extend.

Similarly, in the example embodiment, the second inclined surfaces305bare curved surfaces. Therefore, the second MR elements50C are curved along the curved surfaces (the second inclined surfaces305b). For the sake of convenience, in the present example embodiment, the magnetization directions of the magnetization pinned layers51of the second MR elements50C are defined as straight directions as described above. The W2direction and the −W2direction that are the magnetization directions of the magnetization pinned layers51of the second MR elements50C are also directions in which the tangents to the second inclined surfaces305bat the vicinity of the second MR elements50C extend.

As shown inFIG.5, the plurality of first MR elements50B are disposed so that two or more MR elements50B are arranged both in the U direction and in the V direction. The plurality of first MR elements50B are aligned in a row on one first inclined surface305a. Similarly, the plurality of second MR elements50C are disposed so that two or more MR elements50C are arranged both in the U direction and in the V direction. The plurality of second MR elements50C are aligned in a row on one second inclined surface305b. In the example embodiment, the row of the plurality of first MR elements50B and the row of the plurality of second MR elements50C are alternately arranged in the direction parallel to the V direction.

Note that one first MR element50B and one second MR element50C adjoining each other may or may not deviate in the direction parallel to the U direction when seen in the Z direction. Two first MR elements50B adjoining each other across one second MR element50C may or may not deviate in the direction parallel to the U direction when seen in the Z direction. Two second MR elements50C adjoining each other across one first MR element50B may or may not deviate in the direction parallel to the U direction when seen in the Z direction.

The plurality of first MR elements50B are connected in series by the plurality of lower electrodes61B and the plurality of upper electrodes62B. Herein, a method for connecting the plurality of first MR elements50B will be described in detail with reference toFIG.7. InFIG.7, the reference sign61denotes a lower electrode corresponding to a given MR element50, and the reference numeral62denotes an upper electrode corresponding to the given MR element50. As shown inFIG.7, each lower electrode61has a long slender shape. Two lower electrodes61adjoining in the longitudinal direction of the lower electrodes61have a gap therebetween. MR elements50are disposed near both longitudinal ends on the top surface of each lower electrode61. Each upper electrode62has a long slender shape, and electrically connects two adjoining MR elements50that are disposed on two lower electrodes61adjoining in the longitudinal direction of the lower electrodes61.

Although not shown, one MR element50located at the end of a row of a plurality of aligned MR elements50is connected to another MR element50located at the end of another row of a plurality of MR elements50adjoining in a direction intersecting with the longitudinal direction of the lower electrodes61. Such two MR elements50are connected to each other by a not-shown electrode. The not-shown electrode may be an electrode that connects the bottom surfaces or the top surfaces of the two MR elements50.

In a case where the MR elements50shown inFIG.7are the first MR elements50B, the lower electrodes61shown inFIG.7correspond to the lower electrodes61B, and the upper electrodes62shown inFIG.7correspond to the upper electrodes62B. In such a case, the longitudinal direction of the lower electrodes61is parallel to the U direction.

Similarly, the plurality of second MR elements50C are connected in series by the plurality of lower electrodes61C and the plurality of upper electrodes62C. The foregoing description of the method for connecting the plurality of first MR elements50B holds true also for the method for connecting the plurality of second MR elements50C. In a case where the MR elements50shown inFIG.7are the second MR elements50C, the lower electrodes61shown inFIG.7correspond to the lower electrodes61C, and the upper electrodes62shown inFIG.7correspond to the upper electrodes62C. In such a case, the longitudinal direction of the lower electrodes61is parallel to the U direction.

Each of the plurality of upper coil elements82extends in a direction parallel to the Y direction. The plurality of upper coil elements82are arranged in the X direction. In particular, in the present example embodiment, when seen in the Z direction, each of the plurality of first MR elements50B and the plurality of second MR elements50C overlaps two upper coil elements82.

Each of the plurality of lower coil elements81extends in a direction parallel to the Y direction. The plurality of lower coil elements81are arranged in the X direction. The shape and arrangement of the plurality of lower coil elements81may be the same as or different from those of the plurality of upper coil elements82. In the example shown inFIGS.5and6, the dimension in the X direction of each of the plurality of lower coil elements81is smaller than the dimension in the X direction of each of the plurality of upper coil elements82. The distance between two lower coil elements81adjoining in the X direction is smaller than the distance between two upper coil elements82adjoining in the X direction.

In the example shown inFIGS.5and6, the plurality of lower coil elements81and the plurality of upper coil elements82are electrically connected so as to constitute the coil80that applies a magnetic field in a direction parallel to the X direction to the free layer53in each of the plurality of first MR elements50B and the plurality of second MR elements50C. Alternatively, the coil80may be configured to be able to, for example, apply a magnetic field in the X direction to the free layers53in the first and second resistor sections R21and R22of the first detection circuit20and the first and second resistor sections R31and R32of the second detection circuit30, and apply a magnetic field in the −X direction to the free layers53in the third and fourth resistor sections R23and R24of the first detection circuit20and the third and fourth resistor sections R33and R34of the second detection circuit30. The coil80may be controlled by the processor40.

Next, the first and second detection signals will be described. First, the first detection signal will be described with reference toFIG.3. As the strength of the component of the target magnetic field in the direction parallel to the W1direction changes, the resistance of each of the resistor sections R21to R24of the first detection circuit20changes either so that the resistances of the resistor sections R21and R23increase and the resistances of the resistor sections R22and R24decrease or so that the resistances of the resistor sections R21and R23decrease and the resistances of the resistor sections R22and R24increase. Thereby the electric potential of each of the signal output ports E21and E22changes. The first detection circuit20generates a signal corresponding to the electric potential of the signal output port E21as a first detection signal S21, and generates a signal corresponding to the electric potential of the signal output port E22as a first detection signal S22.

Next, the second detection signal will be described with reference toFIG.4. As the strength of the component of the target magnetic field in the direction parallel to the W2direction changes, the resistance of each of the resistor sections R31to R34of the second detection circuit30changes either so that the resistances of the resistor sections R31and R33increase and the resistances of the resistor sections R32and R34decrease or so that the resistances of the resistor sections R31and R33decrease and the resistances of the resistor sections R32and R34increase. Thereby the electric potential of each of the signal output ports E31and E32changes. The second detection circuit30generates a signal corresponding to the electric potential of the signal output port E31as a second detection signal S31, and generates a signal corresponding to the electric potential of the signal output port E32as a second detection signal S32.

Next, the operation of the processor40will be described. The processor40is configured to generate the first detection value and the second detection value based on the first detection signals S21and S22and the second detection signals S31and S32. The first detection value is a detection value corresponding to the component of the target magnetic field in the direction parallel to the V direction. The second detection value is a detection value corresponding to the component of the target magnetic field in the direction parallel to the Z direction. The first detection value is represented by a symbol Sv, and the second detection value is represented by a symbol Sz.

The processor40generates the first and second detection values Sv and Sz as follows, for example. First, the processor40generates a value S1by an arithmetic including obtainment of the difference S21−S22between the first detection signal S21and the first detection signal S22, and generates a value S2by an arithmetic including obtainment of the difference S31−S32between the second detection signal S31and the second detection signal S32. Next, the processor40calculates values S3and S4using the following expressions (1) and (2).
S3=(S2+S1)/(2 cos α)  (1)
S4=(S2−S1)/(2 sin α)  (2)

The first detection value Sv may be the value S3itself, or may be a result of a predetermined correction, such as a gain adjustment or an offset adjustment, made to the value S3. In the same manner, the second detection value Sz may be the value S4itself, or may be a result of a predetermined correction, such as a gain adjustment or an offset adjustment, made to the value S4.

Next, features of the structure of the magnetic sensor1according to the example embodiment will be described. First, a first example will be described.FIG.8is a sectional view showing first and second insulating portions of the first example.

FIG.8shows a cross section crossing the MR element50disposed on a given inclined surface305eand parallel to a VZ plane. Hereinafter, a cross section parallel to the VZ plane will be referred to as a VZ cross section. The VZ cross section shown inFIG.8may be the one in which a cross section of the MR element50is seen from a position on the side of the U direction as inFIG.6. In such a case, the MR element50, the lower electrode61, and the inclined surface305erespectively correspond to the first MR element50B, the lower electrode61B, and the first inclined surface305a. Alternatively, the VZ cross section shown inFIG.8may be the one in which a cross section of the MR element50is seen from a position on the side of the −U direction. In such a case, the MR element50, the lower electrode61, and the inclined surface305erespectively correspond to the second MR element50C, the lower electrode61C, and the second inclined surface305b.

Herein, as shown inFIGS.8and9, a first direction D1and a second direction D2parallel to the VZ plane are defined. The first direction D1is a direction lying along the inclined surface305eand is also a direction away from a reference plane. In the present example embodiment, it is assumed that the top surface301aof the substrate301(seeFIG.6) is the reference plane. The Z direction is one direction perpendicular to the reference plane (the top surface301aof the substrate301). The second direction D2is a direction lying along the inclined surface305eand is also a direction closer to the reference plane (the top surface301aof the substrate301).

In the following description, a direction that lies along the inclined surface305eand is parallel to the first direction D1(a direction parallel to the second direction D2) will be simply referred to as a direction along the inclined surface305e. Such a direction is also a direction that lies along the inclined surface305eand in which a distance from the reference plane (the top surface301aof the substrate301) changes.

The MR element50includes a bottom surface50afacing the inclined surface305e, a top surface50bon the side opposite to the bottom surface50a, a first side surface50c, and a second side surface50d. The first side surface50cconnects an end portion of the bottom surface50aon the side of the second direction D2and an end portion of the top surface50bon the side of the second direction D2. The second side surface50dis disposed forward of the first side surface50cin the first direction D1. The second side surface50dconnects an end portion of the bottom surface50aon the side of the first direction D1and an end portion of the top surface50bon the side of the first direction D1.

The lower electrode61is provided between the MR element50and the inclined surface305e. The lower electrode61includes a bottom surface61afacing the inclined surface305e, a top surface61bon a side opposite to the bottom surface61a, and two side surfaces (seeFIG.6) each connecting the bottom surface61aand the top surface61b. Note that the lower electrode61may be formed on a region from the inclined surface305eto the flat surface305d. In such a case, one of the two side surfaces of the lower electrode61is disposed on the inclined surface305eand the other is disposed on the flat surface305d. Alternatively, the entire lower electrode61may be disposed on the inclined surface305e. In such a case, both the two side surfaces of the lower electrode61are disposed on the inclined surface305e.

The magnetic sensor1includes a first insulating portion311and a second insulating portion312. Each of the first and second insulating portions311and312may include a single insulating layer or a plurality of insulating layers. In particular, in the present example embodiment, each of the first and second insulating portions311and312includes the insulating layers306and308shown inFIG.6. Note that each of the insulating layers306and308may also include a single insulating film or a plurality of insulating films.

Since each of the insulating layers306and308is formed of an insulating material, each of the first and second insulating portions311and312is also formed of an insulating material. Al2O3or SiO2, for example, is used as an insulating material for forming each of the first and second insulating portions311and312(each of the insulating layers306and308).

The first insulating portion311is disposed on a part of the MR element50. In particular, in the present example embodiment, the first insulating portion311is disposed on the first side surface50cof the MR element50and on a part of the top surface50bof the MR element50.

The second insulating portion312is disposed on another part of the MR element50at a position forward of the first insulating portion311in the first direction D1. In particular, in the present example embodiment, the second insulating portion312is disposed on the second side surface50dof the MR element50and on another part of the top surface50bof the MR element50.

The upper electrode62(seeFIG.7) is disposed on the MR element50, the first insulating portion311, and the second insulating portion312, and is electrically connected to the MR element50. A part of each of the first and second insulating portions311and312is provided between the MR element50and the upper electrode62. Another part of each of the first and second insulating portions311and312is provided between the lower electrode61and the upper electrode62.

The description has been made heretofore of the structural features of the magnetic sensor1focusing on a single inclined surface305e(a single first inclined surface305aor a single second inclined surface305b). In the present example embodiment, there are a plurality of first inclined surfaces305aand a plurality of second inclined surfaces305b. The foregoing description of the single inclined surface305eholds true also for each of the plurality of first inclined surfaces305aand the plurality of second inclined surfaces305b.

Now, focus attention on a single first inclined surface305aand a single second inclined surface305bincluded in a single projecting surface305c, a single first MR element50B disposed on the single first inclined surface305a, and a single second MR element50C disposed on the single second inclined surface305b(seeFIG.6). The second insulating portion312disposed on a part of the first MR element50B and the second insulating portion312disposed on a part of the second MR element50C may be a single continuous undivided insulating portion. In particular, in the present example embodiment, a part, which is continuous, of the insulating layer308is formed above a region from the first inclined surface305ato the second inclined surface305b.

Next, focus attention on the two projecting surfaces305cadjoining in the direction parallel to the V direction, the first inclined surface305aincluded in the projecting surface305con the side of the −V direction, the second inclined surface305bincluded in the projecting surface305con the side of the V direction, the single first MR element50B disposed on the single first inclined surface305a, and the single second MR element50C disposed on the single second inclined surface305b(seeFIG.6). The first insulating portion311disposed on a part of the first MR element50B and the first insulating portion311disposed on a part of the second MR element50C may be a single continuous undivided insulating portion. In particular, in the present example embodiment, a part, which is continuous, of the insulating layer308is formed above a region from the first inclined surface305ato the second inclined surface305b.

Though not shown, the first insulating portion311and the second insulating portion312may also be a single continuous undivided insulating portion. In particular, in the present example embodiment, the insulating layer308may be formed above the plurality of first inclined surfaces305aand the plurality of second inclined surfaces305bwithout being divided. The insulating layer306may be formed around the first MR element50B without being divided above each of the plurality of first inclined surfaces305a. Similarly, the insulating layer306may be formed around the second MR element50C without being divided above each of the plurality of second inclined surfaces305b.

Next, a second example will be described.FIG.9is a sectional view showing the first and second insulating portions311and312of the second example. In the second example, the area of the top surface50bof the MR element50covered with the first insulating portion311is larger than the area of the top surface50bof the MR element50covered with the second insulating portion312.

Next, a third example will be described.FIG.10is a sectional view showing the first and second insulating portions311and312of the third example. In the third example, the area of the top surface50bof the MR element50covered with the second insulating portion312is larger than the area of the top surface50bof the MR element50covered with the first insulating portion311.

Next, a fourth example will be described.FIG.11is a sectional view showing the first and second insulating portions311and312of the fourth example. In the fourth example, the second insulating portion312covers the second side surface50dof the MR element50, but does not cover the top surface50bof the MR element50.

Next, operations and effects of the magnetic sensor1according to the example embodiment will be described. In the present example embodiment, the insulating layers306and308are disposed around each MR element50. Each of the first and second insulating portions311and312includes the insulating layers306and308. The insulating portions (insulating layers) disposed around each MR element50are known to influence the characteristics of the MR element50. In the present example embodiment, the first insulating portion311is disposed on a part of the MR element50, and the second insulating portion312is disposed on another part of the MR element50. Thereby. according to the present example embodiment, desired characteristics can be achieved.

Hereinafter, the sensitivity of the MR element50will be described as an example of the characteristics of the MR element50. The free layer53has a shape anisotropy that sets the direction of the magnetization easy axis to be parallel to the U direction. In a case where a target magnetic field is not applied to the MR element50, the magnetization direction of the free layer53is the U direction or the −U direction. In the MR element50with such a configuration, if the anisotropy of the free layer53in a direction orthogonal to the U direction is increased, the magnetization direction of the free layer53becomes more likely to change, with the result that the sensitivity of the MR element50improves.

For example, it is possible to increase the anisotropy of the free layer53in the direction orthogonal to the U direction by forming the free layer53using a negative magnetostrictive layer and forming the first and second insulating portions311and312using an insulating layer that applies a compressive stress to the free layer53. In particular, in the present example embodiment, the first insulating portion311is disposed on a part of the MR element50, and the second insulating portion312is disposed on another part of the MR element50. In particular, in the present example embodiment, at least one of the first insulating portion311or the second insulating portion312is disposed on the top surface50bof the MR element50. Thereby, according to the present example embodiment, the anisotropy of the free layer53in the direction orthogonal to the U direction can be increased than a case where the first and second insulating portions311and312are not disposed on a part of the MR element50, and thus, the sensitivity of the MR element50can be improved.

By the way, the MR element50is formed on the inclined surface305e. Each of the first and second side surfaces50cand50dis tapered due to restrictions on the production process of forming the MR element50. Therefore, the area of the free layer53located at a position away from the inclined surface305ebecomes small, and the outer peripheral length of the free layer53also becomes short. In a case where the first and second insulating portions311and312are not disposed on a part of the MR element50, it may be impossible to apply a sufficiently high compressive stress to the free layer53. In contrast, in the present example embodiment, the first and second insulating portions311and312are disposed on a part of the MR element50as described above. Thereby, according to the present example embodiment, a sufficiently high compressive stress can be applied to the free layer53.

Note that the magnitude of the compressive stress applied to the free layer53can be controlled by controlling the amounts of the first and second insulating portions311and312disposed on each MR element50or adjusting the configuration of each of the first and second insulating portions311and312. For example, in a case where each of the first and second insulating portions311and312has a three-layer structure of Al2O3/SiO2/Al2O3, the magnitude of the compressive stress can be adjusted by changing the proportion of the thickness of each layer.

When the compressive stress applied to the free layer53is increased, the sensitivity hysteresis of the MR element50may increase. The sensitivity hysteresis of the MR element50can be adjusted by controlling the magnitude of the compressive stress applied to the free layer53as described above.

Note that the description has been made heretofore of an example case where the free layer53is disposed at a position farther from the inclined surface305ethan a position where the magnetization pinned layer51is disposed as shown inFIG.7. However, the configuration of the MR element50is not limited to the example shown inFIG.7, and the magnetization pinned layer51may be disposed at a position farther from the inclined surface305ethan a position where the free layer53is disposed. In such a case, the material of each of the magnetization pinned layer51, the first insulating portion311, and the second insulating portion312may be selected so that the magnetization direction of the magnetization pinned layer51becomes less likely to change. In such a case, it is possible to more easily suppress changes in the magnetization direction of the magnetization pinned layer51by disposing the first and second insulating portions311and312on a part of the MR element50than a case where the first and second insulating portions311and312are not disposed on a part of the MR element50.

Second Example Embodiment

A magnetic sensor according to a second example embodiment of the technology will now be described with reference toFIG.12.FIG.12is a sectional view showing a part of the magnetic sensor1according to the present example embodiment.

In the present example embodiment, each of the plurality of protruding surfaces305cof the insulating layer305has a triangular roof-like overall shape formed by moving the triangular shape of the protruding surface305cshown inFIG.12in the direction parallel to the U direction. All the plurality of first inclined surfaces305aand the plurality of second inclined surfaces305bof the insulating layer305are flat surfaces. Each of the plurality of first inclined surfaces305ais a flat surface parallel to the U direction and the W1direction. Each of the plurality of second inclined surfaces305bis a flat surface parallel to the U direction and the W2direction.

Like the example shown inFIG.6, the insulating layer305may include a plurality of protrusions for forming the plurality of protruding surfaces305c. Alternatively, the insulating layer305may include a plurality of slopes arranged in the direction parallel to the V direction. The plurality of slopes each include a first wall surface corresponding to a first inclined surface305aand a second wall surface corresponding to a second inclined surface305b. A protruding surface305cis constituted by the first wall surface of one slope and the second wall surface of another slope adjoining on the −V direction side of the one slope.

In the example shown inFIG.12, the plurality of slopes each have a bottom surface corresponding to the flat surface305d. However, the plurality of slopes do not need to have a bottom surface each.

The configuration, operation, and effects of the present example embodiment are otherwise the same as those of the first example embodiment.

The technology is not limited to the foregoing example embodiments, and various modifications may be made thereto. For example, the shape of each of the first and second insulating portions311and312is not limited to the example shown in each example embodiment, and may be any shape as long as the requirements of the claims are met.

The magnetic sensor1may further include a third detection circuit configured to detect a component of the target magnetic field in a direction parallel to the XY plane, and generate at least one third detection signal having a correspondence with the component. In such a case, the processor40may be configured to generate a detection value corresponding to a component of the target magnetic field in the direction parallel to the U direction based on the at least one third detection signal. The third detection circuit may be integrated with the first and second detection circuits20and30, or may be included in a chip separate from the first and second detection circuits20and30.

As described above, the magnetic sensor according to one embodiment of the technology includes a substrate including a reference plane; a support member disposed on the substrate, the support member including at least one inclined surface inclined with respect to the reference plane; at least one magnetic detection element disposed on the at least one inclined surface; a first insulating portion of an insulating material disposed on a part of the at least one magnetic detection element; and a second insulating portion of an insulating material disposed on another part of the at least one magnetic detection element at a position forward of the first insulating portion in a direction along the at least one inclined surface, the direction being a direction away from the reference plane.

The magnetic sensor according to one embodiment of the technology may further include an upper electrode disposed on the at least one magnetic detection element, the first insulating portion, and the second insulating portion, the upper electrode being electrically connected to the at least one magnetic detection element. The magnetic sensor according to one embodiment of the technology may further include a lower electrode provided between the at least one magnetic detection element and the at least one inclined surface, the lower electrode being electrically connected to the at least one magnetic detection element.

In the magnetic sensor according to one embodiment of the technology, the at least one magnetic detection element may include a bottom surface facing the at least one inclined surface, a top surface on a side opposite to the bottom surface, and first and second side surfaces each connecting the bottom surface and the top surface. The first insulating portion may be disposed on at least the first side surface. The second insulating portion may be disposed on at least the second side surface. The first insulating portion may be further disposed on a part of the top surface of the at least one magnetic detection element. The second insulating portion may be further disposed on a part of the top surface of the at least one magnetic detection element. Alternatively, the second insulating portion may not be disposed on the top surface of the at least one magnetic detection element.

In the magnetic sensor according to one embodiment of the technology, the at least one inclined surface may be a curved surface. Alternatively, the at least one inclined surface may be a flat surface.

In the magnetic sensor according to one embodiment of the technology, the at least one inclined surface may include a first inclined surface and a second inclined surface facing different directions. The at least one magnetic detection element may include a first magnetic detection element disposed on the first inclined surface and a second magnetic detection element disposed on the second inclined surface. The support member may include a projecting surface projecting in a direction away from the reference plane. The projecting surface may include the first inclined surface and the second inclined surface. The second insulating portion disposed on the first magnetic detection element and the second insulating portion disposed on the second magnetic detection element may be a single insulating portion.

In the magnetic sensor according to one embodiment of the technology, the at least one inclined surface may include a first inclined surface and a second inclined surface facing different directions. The at least one magnetic detection element may include a first magnetic detection element disposed on the first inclined surface and a second magnetic detection element disposed on the second inclined surface. The support member may include a first projecting surface and a second projecting surface each projecting in a direction away from the reference plane. The first projecting surface may include the first inclined surface. The second projecting surface may include the second inclined surface. The first insulating portion disposed on the first magnetic detection element and the first insulating portion disposed on the second magnetic detection element may be a single insulating portion.

In the magnetic sensor according to one embodiment of the technology, each of the first insulating portion and the second insulating portion may include a first insulating layer of an insulating material and a second insulating layer of an insulating material disposed on the first insulating layer. The at least one magnetic detection element may include a bottom surface facing the at least one inclined surface, a top surface on a side opposite to the bottom surface, and first and second side surfaces each connecting the bottom surface and the top surface. The first insulating layer may be in contact with the first side surface and the second side surface.

Obviously, various modification examples and variations of the technology are possible in the light of the above teachings. Thus, it is to be understood that, within the scope of the appended claims and equivalents thereof, the technology may be practiced in other embodiments than the foregoing example embodiments.