Patent ID: 12189003

DETAILED DESCRIPTION

An object of the technology is to provide a magnetic sensor that can reduce the concentration of magnetic charges at the edge of a magnetic layer of a magnetoresistive element to expand a range where a detection signal changes linearly.

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

Example embodiments of the technology will now be described in detail with reference to the drawings. An outline of a magnetic sensor system including a magnetic sensor according to a first example embodiment of the technology will initially be described with reference toFIG.1. A magnetic sensor system100according to the present example embodiment includes a magnetic sensor1according to the present example embodiment and a magnetic field generator5. The magnetic field generator5generates a target magnetic field MF that is a magnetic field for the magnetic sensor1to detect (magnetic field to be detected).

The magnetic field generator5is rotatable about a rotation axis C. The magnetic field generator5includes a pair of magnets6A and6B. The magnets6A and6B are arranged at symmetrical positions with a virtual plane including the rotation axis C at the center. The magnets6A and6B each have an N pole and an S pole. The magnets6A and6B are located in an orientation such that the N pole of the magnet6A is opposed to the S pole of the magnet6B. The magnetic field generator5generates the target magnetic field MF in the direction from the N pole of the magnet6A to the S pole of the magnet6B.

The magnetic sensor1is located at a position where the target magnetic field MF at a predetermined reference position can be detected. The target magnetic field MF at the reference position is part of the magnetic fields generated by the respective magnets6A and6B. The reference position may be located on the rotation axis C. In the following description, the reference position is located on the rotation axis C. The magnetic sensor1detects the target magnetic field MF generated by the magnetic field generator5, and generates a detection value Vs. The detection value Vs has a correspondence with a relative position, or rotational position in particular, of the magnetic field generator5with respect to the magnetic sensor1.

The magnetic sensor system100can be used as a device for detecting the rotational position of a rotatable moving part in an apparatus that includes the moving part. Examples of such an apparatus include a joint of an industrial robot.FIG.1shows an example where the magnetic sensor system100is applied to an industrial robot200.

The industrial robot200shown inFIG.1includes a moving part201and a support unit202that rotatably supports the moving part201. The moving part201and the support unit202are connected at a joint. The moving part201rotates about the rotation axis C. For example, if the magnetic sensor system100is applied to the joint of the industrial robot200, the magnetic sensor1may be fixed to the support unit202, and the magnets6A and6B may be fixed to the moving part201.

Now, we define X, Y, and Z directions as shown inFIG.1. The X, Y, and Z directions are orthogonal to one another. In the present example embodiment, a direction parallel to the rotation axis C (inFIG.1, a direction out of the plane of the drawing) will be referred to as the X direction. InFIG.1, the Y direction is shown as a rightward direction, and the Z direction is shown as an upward direction. The opposite directions to the X, Y, and Z directions will be referred to as −X, −Y, and −Z directions, respectively. As used herein, the term “above” refers to positions located forward of a reference position in the Z direction, and “below” refers to positions located on a side of the reference position opposite to “above”.

In the present example embodiment, the direction of the target magnetic field MF at the reference position is expressed as a direction within the YZ plane including the reference position on the rotation axis C. The direction of the target magnetic field MF at the reference position rotates about the reference position within the foregoing YZ plane.

The magnetic sensor1includes magnetoresistive elements (hereinafter, referred to as MR elements) whose resistances change with an external magnetic field. In the present example embodiment, the resistances of the MR elements change with a change in the direction of the target magnetic field MF. The magnetic sensor1generates detection signals corresponding to the resistances of the MR elements, and generates a detection value Vs based on the detection signals.

Next, a configuration of the magnetic sensor1according to the present example embodiment will be described. An example of a circuit configuration of the magnetic sensor1will initially be described with reference toFIG.2. In the example shown inFIG.2, the magnetic sensor1includes four resistor sections11,12,13, and14, two power supply nodes V1and V2, two ground nodes G1and G2, and two signal output nodes E1and E2.

The resistor sections11to14each include at least one MR element30. If each of the resistor sections11to14includes a plurality of MR elements30, the plurality of MR elements30in each of the resistor sections11to14may be connected in series.

The resistor section11is provided between the power supply node V1and the signal output node E1. The resistor section12is provided between the signal output node E1and the ground node G1. The resistor section13is provided between the power supply node V2and the signal output node E2. The resistor section14is provided between the signal output node E2and the ground node G2. The power supply nodes V1and V2are configured to receive a power supply voltage of predetermined magnitude. The ground nodes G1and G2are connected to the ground.

The potential of the connection point between the resistor section11and the resistor section12changes depending on the resistance of the at least one MR element30of the resistor section11and the resistance of the at least one MR element30of the resistor section12. The signal output node E1outputs a signal corresponding to the potential of the connection point between the resistor section11and the resistor section12as a detection signal S1.

The potential of the connection point between the resistor section13and the resistor section14changes depending on the resistance of the at least one MR element30of the resistor section13and the resistance of the at least one MR element30of the resistor section14. The signal output node E2outputs a signal corresponding to the potential of the connection point between the resistor section13and the resistor section14as a detection signal S2.

The magnetic sensor1further includes a detection value generation circuit21that generates the detection value Vs on the basis of the detection signals S1and S2. The detection value generation circuit21includes an application specific integrated circuit (ASIC) or a microcomputer, for example.

Next, the configuration of the magnetic sensor1will be described in more detail with attention focused on one MR element30.FIG.3is a schematic diagram showing a part of the magnetic sensor1.FIG.4is a cross-sectional view showing a part of the magnetic sensor1.FIG.4shows a cross section parallel to the YZ plane and intersecting the MR element30.FIG.5is a plan view showing a part of the magnetic sensor1.

The magnetic sensor1further includes a support member60. The support member60supports all the MR elements30included in the resistor sections11to14. As shown inFIGS.3and4, the support member60includes an opposed surface60aopposed, at least in part, to the MR elements30, and a bottom surface60blocated opposite the opposed surface60a. The opposed surface60ais located at an end of the support member60in the Z direction. The bottom surface60bis located at an end of the support member60in the −Z direction. The bottom surface60bis parallel to the XY plane. The bottom surface60bcorresponds to the reference plane in the technology. For example, the magnetic sensor1may be manufactured with the bottom surface60bor a surface corresponding to the bottom surface60bmade horizontal. For example, the magnetic sensor1may be installed based on the direction or tilt of the bottom surface60bor the surface corresponding to the bottom surface60b. The bottom surface60bmay thus serve as a reference plane in at least either the manufacturing or the installing of the magnetic sensor1.

At least a part of the opposed surface60aof the support member60is inclined relative to the reference plane, i.e., the bottom surface60b. In the present example embodiment, the opposed surface60aincludes a flat portion60a1parallel to the bottom surface60band at least one curved portion60a2not parallel to the bottom surface60b. As shown inFIG.4, the curved portion60a2is a convex surface protruding in a direction away from the bottom surface60b. The curved portion60a2has a curved shape (arch shape) curved to protrude in a direction away from the bottom surface60b(Z direction) in a given cross section parallel to the YZ plane. In a given cross section parallel to the YZ plane, the distance from the bottom surface60bto the curved portion60a2is maximized at the center of the curved portion60a2in a direction parallel to the Y direction (hereinafter, referred to simply as the center of the curved portion60a2).

The curved portion60a2extends along the X direction. As shown inFIG.3, the overall shape of the curved portion60a2is a semicylindrical curved surface formed by moving the curved shape (arch shape) shown inFIG.4along the X direction.

At least a part of the MR element30is located on the curved portion60a2. A portion of the curved portion60a2from an edge at the end of the curved portion60a2in the −Y direction to the center of the curved portion60a2will be referred to as a first inclined surface and be denoted by the reference symbol SL1. A portion of the curved portion60a2from an edge at the end of the curved portion60a2in the Y direction to the center of the curved portion60a2will be referred to as a second inclined surface and be denoted by the reference symbol SL2. InFIG.3, the border between the first inclined surface SL1and the second inclined surface SL2is shown by a dotted line. Both the first and second inclined surfaces SL1and SL2are inclined relative to the reference plane, i.e., the bottom surface60b. In the present example embodiment, the entire MR element30is located on the first inclined surface SL1or the second inclined surface SL2.FIGS.3and4show how the MR element30is located on the first inclined surface SL1.

The MR element30has a shape that is long in the X direction. As employed herein, the lateral direction of the MR element30will be referred to as the width direction of the MR element30or simply as the width direction. The MR element30may have a planar shape (shape seen in the Z direction), like a rectangle, including a constant width portion having a constant or substantially constant width in the width direction regardless of the position in the X direction. The MR element30may have a planar shape including no constant width portion, like an ellipse. Examples of the planar shape of the MR element30including a constant width portion include a rectangular shape where both longitudinal ends are straight, an oval shape where both longitudinal ends are semicircular, and a shape where both longitudinal ends are polygonal.FIG.3shows an example where the MR element30has a rectangular planar shape. In a second modification example to be described later, the MR element30will be described to have an oval planar shape. The MR element30has a width that is a dimension in the direction parallel to the Y direction. This dimension of the MR element30in the width direction is constant or substantially constant regardless of the position in the X direction.

The support member60includes a substrate61and an insulating layer62located on the substrate61. The substrate61is a semiconductor substrate made of a semiconductor such as Si, for example. The substrate61has a top surface located at an end of the substrate61in the Z direction, and a bottom surface located at an end of the substrate61in the −Z direction. The bottom surface60bof the support member60is constituted by the bottom surface of the substrate61. The substrate61has a constant thickness (dimension in the Z direction).

The insulating layer62is made of an insulating material such as SiO2, for example. The insulating layer62includes a top surface located at an end in the Z direction. The opposed surface60aof the support member60is constituted by the top surface of the insulating layer62. The insulating layer62has a cross-sectional shape such that the curved surface portion60a2is formed on the opposed surface60a. Specifically, the insulating layer62has a cross-sectional shape of bulging out in the Z direction in a given cross section parallel to the YZ plane.

The magnetic sensor1further includes a lower electrode41, an upper electrode42, and insulating layers63,64and65. InFIG.3, the lower electrode41, the upper electrode42, and the insulating layers63to65are omitted. InFIG.5, the insulating layers63to65are omitted.

The lower electrode41is located on the opposed surface60aof the support member60(the top surface of the insulating layer62). The insulating layer63is located on the opposed surface60aof the support member60, around the lower electrode41. The MR element30is located on the lower electrode41. The insulating layer64is located on the lower electrode41and the insulating layer63, around the MR element30. The upper electrode42is located on the MR element30and the insulating layer64. The insulating layer65is located on the insulating layer64, around the upper electrode42.

The magnetic sensor1further includes a non-shown insulating layer covering the upper electrode42and the insulating layer65. The lower electrode41and the upper electrode42are made of a conductive material such as Cu, for example. The insulating layers63to65and the non-shown insulating layer are made of an insulating material such as SiO2, for example.

The substrate61and the portions of the magnetic sensor1stacked on the substrate61are referred to collectively as a detection unit.FIG.4can be said to show the detection unit. The detection value generation circuit21shown inFIG.2may be integrated with or separate from the detection unit.

Now, the configuration of the MR element30will be described in detail with reference toFIG.6. In particular, in the present example embodiment, the MR element30is a spin-valve MR element of current perpendicular-to-plane (CPP) structure. As shown inFIG.6, the MR element30includes a magnetization pinned layer32having a magnetization whose direction is fixed, a free layer34having a magnetization whose direction is variable depending on the direction of an external magnetic field, and a spacer layer33located between the magnetization pinned layer32and the free layer34. The MR element30may be a tunneling magnetoresistive (TMR) element or a giant magnetoresistive (GMR) element. In the TMR element, the spacer layer33is a tunnel barrier layer. In the GMR element, the spacer layer33is a nonmagnetic conductive layer. The resistance of the MR element30changes with an angle that the direction of the magnetization of the free layer34forms with respect to the direction of the magnetization of the magnetization pinned layer32. The resistance is minimized if the angle is 0°. The resistance is maximized if the angle is 180°.

The magnetization pinned layer32, the spacer layer33, and the free layer34are stacked in this order from the lower electrode41in the direction toward the upper electrode42. The MR element30further includes an underlayer31interposed between the magnetization pinned layer32and the lower electrode41, and a cap layer35interposed between the free layer34and the upper electrode42. The arrangement of the magnetization pinned layer32, the spacer layer33, and the free layer34in the MR element30may be vertically reversed from that shown inFIG.6.

The direction of the magnetization of the magnetization pinned layer32is desirably orthogonal to the longitudinal direction of the MR element30. In the present example embodiment, the MR element30is located on the first inclined surface SL1or the second inclined surface SL2inclined relative to the bottom surface60b. The direction of the magnetization of the magnetization pinned layer32is thus also inclined relative to the bottom surface60b.

For the sake of convenience, in the present example embodiment, the direction of the magnetization of the magnetization pinned layer32located on the first inclined surface SL1will be referred to as a U direction or a −U direction. The U direction is a direction rotated from the Y direction toward the Z direction by a predetermined angle. The −U direction is the direction opposite to the U direction. For the sake of convenience, in the present example embodiment, the direction of the magnetization of the magnetization pinned layer32located on the second inclined surface SL2will be referred to as a V direction or a −V direction. The V direction is a direction rotated from the Y direction toward the −Z direction by a predetermined angle. The −V direction is the direction opposite to the V direction.

The X, U and V directions are shown inFIG.2. For the sake of convenience, inFIG.2, the U direction and the V direction are indicated by the same arrow. InFIG.2, the filled arrows indicate the directions of the magnetizations of the magnetization pinned layers32of the MR elements30included in the respective resistor sections11to14. The magnetic sensor1may be configured so that the directions of the magnetizations of the magnetization pinned layers32of the MR elements30in the resistor sections11and14are the U direction, and the directions of the magnetizations of the magnetization pinned layers32of the MR elements30in the resistor sections12and13are the −U direction. Alternatively, the magnetic sensor1may be configured so that the directions of the magnetizations of the magnetization pinned layers32of the MR elements30in the resistor sections11and14are the V direction, and the directions of the magnetizations of the magnetization pinned layers32of the MR elements30in the resistor sections12and13are the −V direction.

Alternatively, the magnetic sensor1may include a first circuit portion and a second circuit portion each including the resistor sections11to14. The first circuit portion may be configured so that the directions of the magnetizations of the magnetization pinned layers32of the MR elements30in the resistor sections11and14are the U direction, and the directions of the magnetizations of the magnetization pinned layers32of the MR elements30in the resistor sections12and13are the −U direction. The second circuit portion may be configured so that the directions of the magnetizations of the magnetization pinned layers32of the MR elements30in the resistor sections11and14are the V direction, and the directions of the magnetizations of the magnetization pinned layers32of the MR elements30in the resistor sections12and13are the −V direction.

The free layer34corresponds to a magnetic layer according to the technology. The free layer34has magnetic shape anisotropy where the direction of the easy axis of magnetization intersects the direction of the magnetization of the magnetization pinned layer32. In the present example embodiment, the MR element30is patterned to a shape that is long in the X direction. This gives the free layer34magnetic shape anisotropy where the direction of the easy axis of magnetization is parallel to the X direction.

Up to this point, the configuration of the magnetic sensor1has been described with attention focused on one MR element30. In the present example embodiment, the resistor sections11to14each include at least one MR element30. The magnetic sensor1thus includes a plurality of MR elements30, a plurality of lower electrodes41, and a plurality of upper electrodes42. As shown inFIG.5, each of the lower electrodes41has a long slender shape. The MR element30is provided on the top surface of the lower electrode41, near one end in the longitudinal direction. Each upper electrode42has a long slender shape and is located over two lower electrodes41to electrically connect two adjoining MR elements30.

The number of curved portions60a2of the opposed surface60aof the support member60may be one or more than one. If the number of curved portions60a2is one, the plurality of MR elements30are located on the one curved portion60a2. In such a case, the plurality of MR elements30may be located on either one of the first and second inclined surfaces SL1and SL2or on both the first and second inclined surfaces SL1and SL2.

If the number of curved portions60a2is more than one, one or a plurality of MR elements30may be located on one curved portion60a2. In such a case, the plurality of curved portions60a2may be arranged along one direction. Alternatively, the plurality of curved portions60a2may be arranged in a plurality of rows, i.e., more than one curved portion60a2in both the X and Y directions.

Next, the MR element30will be described in more detail with reference toFIGS.6and7.FIG.7is an explanatory diagram for describing the shape of the free layer34.FIG.7is an enlarged view of a part of the cross section shown inFIG.4. InFIG.7, the underlayer31and the cap layer35of the MR element30are omitted.

As shown inFIGS.6and7, the free layer34includes a first surface34a, a second surface34bopposite to the first surface34a, and an outer peripheral surface connecting the first surface34aand the second surface34b. The first surface34ais located farther from the opposed surface60aof the support member60than is the second surface34b. The first surface34ais in contact with the cap layer35. The second surface34bis in contact with the spacer layer33.

In the present example embodiment, the MR element30is patterned to a shape that is long in the X direction. The first and second surfaces34aand34bthus each have a shape that is long in the X direction. The first surface34ahas a first edge Ed1and a second edge Ed2located at both lateral ends of the first surface34a. At least either one of the first and second edges Ed1and Ed2is located above the curved portion60a2of the opposed surface60aof the support member60. At least a part of the first surface34ais thus inclined relative to the reference plane, i.e., the bottom surface60bof the support member60. As employed herein, an angle that the first surface34aforms with the bottom surface60bof the support member60will be referred to as an inclination angle and be denoted by the symbol θ. The inclination angle θ is 0° or greater and not greater than 90°. At least a part of the first surface34ais inclined relative to the bottom surface60bof the support member60so that the inclination angle θ is greater than 0°.

The shape of the free layer34can change discontinuously and greatly near the outer peripheral surface. To accurately define the inclination angle θ, in the present example embodiment, both lateral ends of the portion of the first surface34a, not including discontinuously and greatly changing areas, will be referred to, for the sake of convenience, as the first and second edges Ed1and Ed2. The first edge Ed1and the second edge Ed2may be located inside the first surface34a, inside the border between the first surface34aand the outer peripheral surface. If the shape of the free layer34does not change discontinuously, the first edge Ed1and the second edge Ed2fall on the border between the first surface34aand the outer peripheral surface.

In the present example embodiment, both the first and second edges Ed1and the Ed2are located above the first inclined surface SL1of the curved portion60a2or both the first and second edges Ed1and Ed2are located above the second inclined surface SL2of the curved portion60a2. The entire first surface34ais thus inclined relative to the reference plane, i.e., the bottom surface60bof the support member60. The distance from the bottom surface60bof the support member60to the first edge Ed1is smaller than the distance from the bottom surface60bof the support member60to the second edge Ed2.

FIG.7shows a cross section intersecting the free layer34and perpendicular to the longitudinal direction of the first surface34a(direction parallel to the X direction). Such a cross section will hereinafter be denoted by the symbol S. The cross section S is also a cross section parallel to the YZ plane. The inclination angle θ at the first edge Ed1will be referred to as an inclination angle θ1. The inclination angle θ at the second edge Ed2will be referred to as an inclination angle θ2. The inclination angle θ at a predetermined point P on the first surface34abetween the first edge Ed1and the second edge Ed2will be denoted by the symbol Op.

In a given cross section S, the inclination angle θ1at the first edge Ed1is greater than the inclination angle θp at the predetermined point P. In the given cross section S, the inclination angle θ2at the second edge Ed2is smaller than the inclination angle θp. As shown inFIG.7, in the given cross section S, the inclination angle θ increases toward the first edge Ed1from the second edge Ed2. InFIG.7, the predetermined point P refers to the midpoint between the first and second edges Ed1and Ed2on the first surface34ain the given cross section S.

The inclination angle θ at a given position on the first surface34achanges depending on the angle that the opposed surface60aof the support member60forms with the reference plane, i.e., the bottom surface60bof the support member60(hereinafter, referred to as the inclination angle of the opposed surface60a). Specifically, the inclination angle θ at a given position on the first surface34ais substantially the same as the inclination angle of the opposed surface60aat the position on the opposed surface60aclosest to the given position. The inclination angle θ thus increases as the inclination angle of the opposed surface60aincreases.

The free layer34has a thickness T that is a dimension in a direction perpendicular to the first surface34a. The thickness T can also be said to be the distance between the first and second surfaces34aand34bin the direction perpendicular to the first surface34a. The thickness T at the first edge Ed1will be referred to as a thickness T1. The thickness T at the second edge Ed2will be referred to as a thickness T2. The thickness T at the predetermined point P will be referred to as a thickness Tp. For the sake of convenience, an imaginary surface is assumed by extending the second surface34balong the curved portion60a2, and the thickness T2is defined as the distance between the first surface34aand the imaginary surface in the direction perpendicular to the first surface34a.

In a given cross section S, the thickness T1at the first edge Ed1is smaller than the thickness Tp at the predetermined point P. In the given cross section S, the thickness T2at the second edge Ed2is greater than the thickness Tp. As shown inFIG.7, in the given cross section S, the thickness T decreases toward the first edge Ed1from the second edge Ed2.

The thickness T at a given position on the first surface34achanges depending on the inclination angle of the opposed surface60a. Specifically, the thickness T at a given position on the first surface34adecreases as the inclination angle of the opposed surface60aat the position on the opposed surface60aclosest to the given position increases.

From the relationship between the inclination angle θ and the inclination angle of the opposed surface60aand the relationship between the thickness T and the inclination angle of the opposed surface60a, the thickness T decreases as the inclination angle θ increases.

In the present example embodiment, the entire MR element30is located on the first inclined surface SL1or the second inclined surface SL2. The angle that the first inclined surface SL1or the second inclined surface SL2forms with the bottom surface60bof the support member60will hereinafter be referred to as an inclined surface angle and be denoted by the symbol ϕ. As shown inFIG.7, the inclination angle θ at a given position on the first surface34aincreases as the inclined surface angle at the position on the opposed surface60aclosest to the given position increases. As shown inFIG.7, the thickness T at a given position on the first surface34adecreases as the inclined surface angle ϕ at the position on the opposed surface60aclosest to the given position increases. InFIG.7, the inclined surface angle ϕ at a position on the opposed surface60aclosest to the first edge Ed1is denoted by the symbol ϕ1. The inclined surface angle ϕ at a position on the opposed surface60aclosest to the second edge Ed2is denoted by the symbol ϕ2. The inclined surface angle ϕ at a position on the opposed surface60aclosest to the predetermined point P is denoted by the symbol4.

The angle ϕ in a given cross section S is greater at the position on the opposed surface60aclosest to the first edge Ed1than at the position on the opposed surface60aclosest to the predetermined point P. In other words, the angle ϕ1is greater than the angle4. The angle ϕ2is smaller than the angle4. As shown inFIG.7, the angle ϕ in the given cross section S increases toward the position on the opposed surface60aclosest to the first edge Ed1from the position on the opposed surface60aclosest to the second edge Ed2.

Examples of the thickness T and the inclined surface angle ϕ will now be described. The following description will be given by using a case where a TMR element was formed as an MR element30of a practical example on the first inclined surface SL1, as an example. In this example, the TMR element was formed by using a magnetron sputtering apparatus, and the thickness T of the free layer34of the MR element30(TMR element) was measured under a cross-sectional transmission electron microscope (cross-sectional TEM). In the MR element30(TMR element) of the practical example, the distance from the first edge Ed1to the second edge Ed2in a cross section parallel to the YZ plane was 1.3 μm.

In the practical example, the thickness T1at the first edge Ed1was 9.0 nm. The inclined surface angle ϕ1at the position on the opposed surface60aclosest to the first edge Ed1was 39.1°.

In the practical example, the thickness T2at the second edge Ed2was 10.9 nm. The inclined surface angle ϕ2at the position on the opposed surface60aclosest to the second edge Ed2was 25.2°.

In actually fabricating the MR element30, the first surface34aof the free layer34can have so high a surface roughness that effects on various parameters are not negligible. In such a case, to reduce measurement errors, inclination angles θ including the inclination angles θ1, θ2, and θp may be measured in the following manner. Initially, determine average lines (straight lines) of the cross-sectional curve of the first surface34anear the respective measurement points of the inclination angles θ. Then, measure the angles that the average lines form with the bottom surface60bof the support member60as the inclination angles θ at the measurement points by assuming the average lines as the tangents to the first surface34aat the measurement points. The average lines desirably have such a length that the average lines intersect the cross-sectional curve a plurality of times. For example, in the case of the MR element30(TMR element) according to the practical example, the average lines may have a length in the range of 10 to 100 nm. Such an angle measurement method may be employed as the specific definition of the inclination angles θ in the present example embodiment.

To reduce measurement errors, the thicknesses T at the measurement points may be measured by assuming the directions perpendicular to the foregoing average lines as the directions perpendicular to the first surface34a. Alternatively, if the opposed surface60aincluding the curved portion60a2has a lower surface roughness than that of the first surface34a, the thicknesses T at the measurement points may be measured by assuming the directions perpendicular to the opposed surface60aat the positions on the opposed surface60aclosest to the measurement points as the directions perpendicular to the first surface34a. Either one of the foregoing methods for measuring the thickness T may be employed as the specific definition of the thickness T in the present example embodiment.

Next, operation and effects of the magnetic sensor1according to the present example embodiment will be described. In the present example embodiment, in a given cross section S, the thickness T1at the first edge Ed1is smaller than the thickness Tp at the predetermined point P. Moreover, in the present example embodiment, the thickness T2at the second edge Ed2is greater than the thickness Tp in the given cross section S. According to the present example embodiment, the concentration of magnetic charges at and near the first edge Ed1of the free layer34can thus be reduced.

In the present example embodiment, in a given cross section S, the inclination angle θ1at the first edge Ed1is greater than the inclination angle θp at the predetermined point P. Moreover, in the given cross section S, the inclination angle θ2at the second edge Ed2is smaller than the inclination angle θp at the predetermined point P. The inclination angle θ is substantially the same as the inclination angle of the opposed surface60a, and can be controlled by changing the position of the MR element30and/or the inclination angle itself of the opposed surface60a.

As described above, the thickness T decreases as the inclination angle of the opposed surface60aincreases. Such a relationship between the thickness T and the inclination angle of the opposed surface60acan be achieved by forming the MR element30using a so-called non-conformal film formation apparatus such as a magnetron sputtering apparatus. The inclination angles θ can be controlled by the inclination angle of the opposed surface60aand the arrangement of the MR element30. According to the present example embodiment, the thickness T can be controlled by controlling the inclination angles θ as described above.

The effect of reducing the concentration of magnetic charges will be described in detail below by comparison with an MR element230according to a comparative example. The MR element230of the comparative example will initially be described with reference toFIG.8.FIG.8is an explanatory diagram for describing magnetic charges on the MR element230of the comparative example.FIG.8shows a cross section corresponding to the cross section S. Like the MR element30according to the present example embodiment, the MR element230according to the comparative example includes a magnetization pinned layer232, a spacer layer233, a free layer234, and a not-shown underlayer and cap layer.

The MR element230of the comparative example is located on a flat surface parallel to the reference plane (bottom surface60bof the support member60). Like the MR element30according to the present example embodiment, the MR element230is patterned to a shape that is long in the X direction. This gives the free layer234magnetic shape anisotropy where the direction of the easy axis of magnetization is parallel to the X direction.

The free layer234includes a first surface234alocated at an end in the Z direction, a second surface234bopposite to the first surface234a, and an outer peripheral surface connecting the first surface234aand the second surface234b. Both the first and second surfaces234aand234bare flat surfaces parallel to the reference plane. The first and second surfaces234aand234beach have a shape that is long in the X direction. The first surface234ahas a first edge Ed11and a second edge Ed12located at both ends in the lateral direction of the first surface234a, i.e., a direction parallel to the Y direction. In particular, in the comparative example, the first edge Ed11is an edge located at the end of the first surface234ain the −Y direction. The second edge Ed12is an edge located at the end of the first surface234ain the Y direction.

If an external magnetic field is applied to the MR element230, the direction of the magnetic moment inside the free layer234rotates depending on the direction and strength of the external magnetic field. As a result, the direction of the magnetization of the free layer234rotates. Here, magnetic charges occur on the outer peripheral surface of the free layer234.

Now, suppose that an external magnetic field in the Y direction is applied to the MR element230. If the external magnetic field in the Y direction is applied, positive magnetic charges concentrate at a portion of the outer peripheral surface of the free layer234near the second edge Ed12, and negative magnetic charges concentrate at a portion of the outer peripheral surface of the free layer234near the first edge Ed11. InFIG.8, the symbols “+” represent positive magnetic charges, and the symbols “−” negative magnetic charges. A demagnetizing field in the −Y direction occurs in the free layer234due to such magnetic charges. The strength of the demagnetizing field is higher as it is closer to the magnetic charges. The strength of the demagnetizing field in the portions of the free layer234near the first and second edges Ed11and Ed12is therefore high. The strength of the demagnetizing field in the midsection of the free layer234is low.

If no external magnetic field is applied, the direction of the magnetization of the free layer234and the direction of the magnetic moment in the free layer234are parallel to the X direction. If the strength of the external magnetic field is low, the direction of the magnetic moment in the midsection of the free layer234starts to rotate toward the Y direction. On the other hand, the direction of the magnetic moment in the portions of the free layer234near the first and second edges Ed11and Ed12does not rotate or hardly rotates.

If the strength of the external magnetic field becomes high to a certain extent, the direction of the magnetic moment in the midsection of the free layer234becomes the same or substantially the same as the Y direction. Meanwhile, the direction of the magnetic moment in the portions of the free layer234near the first and second edges Ed11and Ed12starts to rotate toward the Y direction. If the strength of the external magnetic field becomes even higher, the direction of the magnetic moment in the portions of the free layer234near the first and second edges Ed11and Ed12also becomes the same or substantially the same as the Y direction.

As described above, in the MR element230of the comparative example, the direction of the magnetic moment in the entire free layer234does not change uniformly because of the demagnetizing field. As a result, the magnetization of the free layer234changes nonlinearly with respect to a change in the strength of the external magnetic field. Consequently, a detection signal generated by a magnetic sensor including the MR element230of the comparative example changes nonlinearly with respect to a change in the strength of the external magnetic field.

Next, magnetic charges on the MR element30according to the present example embodiment will be described.FIG.9is an explanatory diagram for describing magnetic charges on the MR element30.FIG.9shows a cross section corresponding to the cross section S. InFIG.9, the symbols “+” represent positive magnetic charges, and the symbols “−” negative magnetic charges.

In the MR element30according to the present example embodiment, the thickness T1at the first edge Ed1is smaller than the thickness T2at the second edge Ed2. Now, suppose that an external magnetic field in the Y direction is applied to the MR element30. In such a case, positive magnetic charges concentrate at a portion of the outer peripheral surface of the free layer34near the second edge Ed2as in the comparative example. By contrast, negative magnetic charges do not concentrate at a portion of the outer peripheral surface of the free layer34near the first edge Ed1but are distributed even over the first surface34a. This reduces a difference between the strength of the demagnetizing field at the portion of the free layer34near the first edge Ed1and that of the demagnetizing field in the midsection of the free layer34. As the difference decreases, the direction of the magnetic moment at the portion of the free layer34near the first edge Ed1rotates more similarly to that of the magnetic moment in the midsection of the free layer34. According to the present example embodiment, the magnetization of the free layer34can thus be prevented from changing nonlinearly with respect to a change in the strength of the external magnetic field. As a result, according to the present example embodiment, the range where the detection signal generated by the magnetic sensor1change linearly can be expanded.

Next, a result of an experiment for examining the linearity of the detection signal will be described. For the experiment, a magnetic sensor of the practical example and a magnetic sensor of the comparative example were fabricated. The magnetic sensor of the practical example and the magnetic sensor of the comparative example each have basically the same configuration as that of the magnetic sensor1according to the present example embodiment. The magnetic sensor of the practical example includes MR elements30(TMR elements) according to the foregoing practical example as the MR elements30. The magnetic sensor of the comparative example includes MR elements230according to the comparative example instead of the MR elements30. The MR elements230according to the comparative example are TMR elements formed on a flat surface parallel to the reference plane (bottom surface60bof the support member60) by the same method as with the MR elements30according to the practical example.

In the experiment, changes in a detection signal (signal corresponding to the detection signal S1or S2) generated by each of the magnetic sensors of the practical example and the comparative example were examined while changing the strength of the external magnetic field in the Y direction applied to the magnetic sensors.

FIG.10shows the results of the experiment. Here, the strength of the external magnetic field applied to the magnetic sensors is expressed by H, and the strength of the magnetic anisotropy fields in the free layers34and234is expressed by Hk. The horizontal axis ofFIG.10indicates H/Hk. The vertical axis ofFIG.10indicates normalized signals obtained by normalizing the detection signals to a maximum value of 1. InFIG.10, the curve denoted by the reference numeral81represents the normalized signal of the magnetic sensor according to the practical example. The curve denoted by the reference numeral82represents the normalized signal of the magnetic sensor according to the comparative example.

As shown inFIG.10, the normalized signal of the magnetic sensor (reference numeral82) according to the comparative example changes linearly within the range where H/Hk is 0 to 0.7. The normalized signal of the magnetic sensor (reference numeral81) according to the practical example changes linearly within the range where H/Hk is 0 to 0.8. As can be seen fromFIG.10, according to the present example embodiment, the range where the detection signals generated by the magnetic sensor1change linearly can be expanded.

As shown inFIG.8, the end faces of the MR element230in the −Y direction and the Y direction of the comparative example are each tilted relative to the XY plane. To reduce the concentration of magnetic charges at the portions of the outer peripheral surface of the free layer234near the first and second edges Ed11and Ed12in the MR element230of the comparative example, the foregoing end faces can be tilted more greatly. However, the effect of increasing the tilt of the end faces as described above is limited since the MR element typically has a small thickness.

Moreover, the MR element230of the comparative example causes the following problems if the tilt of the end faces is increased. That is, increasing the tilt of the end faces increases regions not covered with the cap layer when seen in the Z direction, and the MR element230can become more prone to corrosion and oxidation. The free layer234is sometimes made of a layered film including a plurality of layers. In such a case, increasing the tilt of the end faces as described above reduces the areas of the layers of the layered film closer to the cap layer, and can change the properties of the free layer234at the edges. Moreover, in forming a plurality of MR elements230, if the tilt of the end faces is increased with the shape of the resist mask unchanged, the width of the tilted part of each of the MR elements230is increased. As a result, the distance between the two adjoining MR elements230decreases. The distance between the two adjoining MR elements230need to be increased to reduce a risk of the two adjoining MR elements230being electrically connected. However, an increase in the distance between the two adjoining MR elements230lowers the integration density of the plurality of MR elements230and results in a decrease in an S/N ratio.

By contrast, in the present example embodiment, the concentration of magnetic charges at the portion of the outer peripheral surface of the free layer34near the first edge Ed1can be reduced without increasing the tilt of the end faces of the MR element30in the −Y direction and the Y direction as described above. In other words, according to the present example embodiment, the concentration of magnetic charges can be reduced while preventing the occurrence of the problems due to the increased tilt of the end faces of the MR element30.

Moreover, in the present example embodiment, the concentration of magnetic charges can easily be reduced by forming the MR element30so that at least a part of the MR element30is located on the curved portion60a2of the opposed surface60a.

The present example embodiment has dealt with the case where the MR element30is located on the curved portion60a2. However, the MR element30may be located on the following inclined portion. The inclined portion includes a plurality of flat surfaces. Of the plurality of flat surfaces, the one closest to the bottom surface60bof the support member60will be referred to as a first flat surface. The flat surface farthest from the bottom surface60bof the support member60will be referred to as a second flat surface. The MR element30is located across the first flat surface and the second flat surface. An angle that the first flat surface forms with the bottom surface60bof the support member60is greater than angles that the respective flat surfaces other than the first flat surface form with the bottom surface60bof the support member60. The angle that the second flat surface forms with the bottom surface60bof the support member60is smaller than the angles that the respective flat surfaces other than the second flat surface form with the bottom surface60bof the support member60.

The present example embodiment has dealt with the case where the entire MR element30is located on the first inclined surface SL1or the second inclined surface SL2of the curved portion60a2. However, as will be described in a second example embodiment, the MR element30may be located across the first inclined surface SL1and the second inclined surface SL2.

The present example embodiment has also dealt with the case where both the first and second edges Ed1and Ed2are located above the first inclined surface SL1or both the first and second edges Ed1and Ed2are located above the second inclined surface SL2. However, if either one of the first and second edges Ed1and Ed2is located above the first inclined surface SL1or the second inclined surface SL2, the other may be located above the flat portion60a1or above the border between the first and second inclined surfaces SL1and SL2.

Modification Examples

Next, modification examples of the present example embodiment will be described. Initially, a first modification example of the MR element30will be described with reference toFIG.11. In the first modification example, the MR element30is an anisotropic magnetoresistive (AMR) element. In the first modification example, the MR element30includes a magnetic layer36given magnetic anisotropy, instead of the magnetization pinned layer32, the spacer layer33, and the free layer34shown inFIG.6. The magnetic layer36has a magnetization whose direction is variable depending on the direction of the external magnetic field. As described above, the MR element30is patterned to a shape that is long in the X direction. This gives the magnetic layer36magnetic shape anisotropy where the direction of the easy axis of magnetization is parallel to the X direction.

The magnetic layer36has a first surface36ahaving a shape that is long in the X direction, a second surface36bopposite to the first surface36a, and an outer peripheral surface connecting the first surface36aand the second surface36b. The description of the shape of the MR element30with reference toFIGS.6and7also applies to the first modification example. The description of the shape of the MR element30applies to the shape of the first modification example, with the free layer34, the first surface34a, and the second surface34bin the description replaced with the magnetic layer36, the first surface36a, and the second surface36b.

Next, a second modification example of the MR element30will be described with reference toFIG.12. In the second modification example, the MR element30has an oval planar shape. The MR element30includes a constant width portion30B, a first width changing portion30A, and a second width changing portion30C. The first width changing portion30A is located in front of the constant width portion30B in the −X direction. The second width changing portion30C is located in front of the constant width portion30B in the X direction. InFIG.12, the border between the constant width portion30B and the first width changing portion30A and the border between the constant width portion30B and the second width changing portion30C are shown by dotted lines.

The constant width portion30B has a constant width (dimension in the direction parallel to the Y direction) regardless of the position in the X direction. The width of the first width changing portion30A decreases with increasing distance from the constant width portion30B. The width of the second width changing portion30C decreases with increasing distance from the constant width portion30B.

The first and second width changing portions30A and30C are provided to control the magnetic domain structure of the free layer34, for example. In the first and second width changing portions30A and30C, a difference between the thickness T2at the second edge Ed2and the thickness T1at the first edge Ed1decreases with increasing distance from the constant width portion30B. This lowers the effect of reducing the concentration of magnetic charges at the portion of the MR element30near the end in the −X direction and the portion of the MR element30near the end in the X direction. However, the difference between the thicknesses T2and T1in the portions other than the foregoing is sufficiently large, whereby the effect of reducing the concentration of magnetic charges can be obtained.

Next, a third modification example of the MR element30will be described with reference toFIGS.13to15. The MR element30shown inFIGS.13to15is a current in-plane (CIP) MR element.FIG.13is an explanatory diagram for describing the third modification example of the MR element30.FIG.14is a cross-sectional view showing a cross section at the position indicated by the line14-14ofFIG.13.FIG.15is a cross-sectional view showing a cross section at the position indicated by the line15-15ofFIG.13. For the sake of convenience,FIGS.14and15show only the MR element30and the support member60.

The MR element30includes a layered film including the underlayer31, the magnetization pinned layer32, the spacer layer33, the free layer34, and the cap layer35(seeFIG.6). This layered film will be denoted by the reference numeral30M. In the third modification example, the dimension of the layered film30M in a direction parallel to the X direction is greater than that of the curved portion60a2of the opposed surface60aof the support member60in the direction parallel to the X direction. A part of the layered film30M is located on the curved portion60a2. Another part of the layered film30M is located on the flat portion60a1of the opposed surface60ain front of the curved portion60a2in the −X direction. Yet another part of the layered film30M is located on the flat portion60a1of the opposed surface60ain front of the curved portion60a2in the X direction. The portion of the layered film30M located on the curved portion60a2will hereinafter be referred to as a curved surface-located portion30M1. The portions of the layered film30M located on the flat portion60a1will be referred to as flat surface-located portions30M2.

In the third modification example, the MR element30further includes a nonmagnetic metal film30N. As shown inFIGS.13and15, the nonmagnetic metal film30N covers the flat surface-located portions30M2. As shown inFIGS.13and15, the nonmagnetic metal film30N does not cover most of the curved surface-located portion30M1.

The flat surface-located portions30M2are substantially the same as the MR element230of the comparative example shown inFIG.8. These portions therefore do not provide the effect of reducing the concentration of magnetic charges. Meanwhile, the curved surface-located portion30M1provides the effect of reducing the concentration of magnetic charges. In the third modification example, the flat surface-located portions30M2are covered with the nonmagnetic metal film30N, whereby only a signal corresponding to the resistance of the curved surface-located portion30M1can be detected from the MR element30. In other words, in the third modification example, only the curved surface-located portion30M1can substantially function as the MR element30. The effect of reducing the concentration of magnetic charges can thus be obtained.

In the third modification example, if the flat surface-located portions30M2are sufficiently small compared to the curved surface-located portion30M1, the nonmagnetic metal film30N may be omitted.

Second Example Embodiment

A second example embodiment of the invention will now be described. Initially, a configuration of a magnetic sensor according to the present example embodiment will be described with reference toFIGS.16and17.FIG.16is a schematic diagram showing a part of the magnetic sensor according to the present example embodiment.FIG.17is a cross-sectional view showing a part of the magnetic sensor according to the present example embodiment.

A magnetic sensor101according to the present example embodiment has the same configuration as that of the magnetic sensor1according to the first example embodiment except for the MR elements. The magnetic sensor101according to the present example embodiment includes MR elements130instead of the MR elements30according to the first example embodiment.FIG.17shows a cross section parallel to the YZ plane and intersecting an MR element130.

The MR element130is located on the curved portion60a2of the opposed surface60aof the support member60. In particular, in the present example embodiment, the MR element130is located across the first inclined surface SL1and the second inclined surface SL2. The MR element130has a shape that is long in the X direction. The MR element130has a rectangular planar shape.

The MR element130may be a spin-valve MR element or an AMR element. The following description will be given by using the case where the MR element130is a spin-valve MR element as an example. Like the MR element30shown inFIG.6according to the first example embodiment, the MR element130includes an underlayer31, a magnetization pinned layer32, a spacer layer33, a free layer34, and a cap layer35. For the sake of convenience, in the present example embodiment, the direction of the magnetization of the magnetization pinned layer32will be referred to as a Y direction or a −Y direction. The free layer34has magnetic shape anisotropy where the direction of the easy axis of magnetization is parallel to the X direction.

Next, the MR element130will be described in more detail with reference toFIG.18.FIG.18is an explanatory diagram for describing the shape of the free layer34.FIG.18is an enlarged view of a part of the cross section shown inFIG.17. InFIG.18, the underlayer31and the cap layer35of the MR element130are omitted.

As described in the first example embodiment, the free layer34has a first surface34a, a second surface34b, and an outer peripheral surface. The first surface34ahas a first edge Ed1and a second edge Ed2located at both lateral ends of the first surface34a. In the present example embodiment, the first edge Ed1is located on the first inclined surface SL1of the curved portion60a2. The second edge Ed2is located on the second inclined surface SL2of the curved portion60a2. The distance from the bottom surface60bof the support member60to the first edge Ed1and the distance from the bottom surface60bof the support member60to the second edge Ed2may be the same or different from each other.

In a given cross section S intersecting the free layer34and perpendicular to the longitudinal direction of the first surface34a(direction parallel to the X direction), both the inclination angle θ1at the first edge Ed1and the inclination angle θ2at the second edge Ed2are greater than the inclination angle θp at a predetermined point P. In the present example embodiment, the predetermined point P refers to a point on the first surface34awhere the inclination angle θ is the smallest. In particular, in the present example embodiment, the inclination angle θ at the predetermined point P is 0. In the given cross section S, the inclination angle θ increases toward the first edge Ed1from the predetermined point P and increases toward the second edge Ed2from the predetermined point P.

In the given cross section S, both the thickness T1at the first edge Ed1and the thickness T2at the second edge Ed2are smaller than the thickness Tp at the predetermined point P. In the given cross section S, the thickness T decreases toward the first edge Ed1from the predetermined point P and decreases toward the second edge Ed2from the predetermined point P.

As in the first example embodiment, an angle that the opposed surface60aforms with the reference plane (bottom surface60bof the support member60) in a given cross section S will be denoted by the symbol ϕ. In the present example embodiment, the angle ϕ at the position on the opposed surface60aclosest to the second edge Ed2is greater than the angle ϕ at the position on the opposed surface60aclosest to the predetermined point P. The angle ϕ increases toward the position on the opposed surface60aclosest to the first edge Ed1from the position on the opposed surface60aclosest to the predetermined point P and increases toward the position on the opposed surface60aclosest to the second edge Ed2from the position on the opposed surface60aclosest to the predetermined point P.

In the present example embodiment, the thickness T2at the second edge Ed2is smaller than that in the first example embodiment where the second edge Ed2is located near the top of the curved portion60a2. According to the present example embodiment, the concentration of magnetic charges at the portion of the outer peripheral surface of the free layer34near the second edge Ed2can thereby be reduced. According to the present example embodiment, the magnetization of the free layer34can thus be more effectively prevented from changing nonlinearly with respect to a change in the strength of the external magnetic field. As a result, according to the present example embodiment, the range where the detection signals generated by the magnetic sensor101change linearly can be expanded.

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

Third Example Embodiment

A third example embodiment of the invention will now be described. Initially, a configuration of a magnetic sensor according to the present example embodiment will be described with reference toFIG.19.FIG.19is a cross-sectional view showing a part of the magnetic sensor according to the present example embodiment.

A configuration of the magnetic sensor301according to the present example embodiment differs from that of the magnetic sensor1according to the first example embodiment in the following respect. The magnetic sensor301according to the present example embodiment includes MR elements330instead of the MR elements30according to the first example embodiment.FIG.19shows a cross section parallel to the YZ plane and intersecting an MR element330.

The opposed surface60aof the support member60includes at least one curved portion60a3not parallel to the bottom surface60bof the support member60, instead of the curved portion60a2according to the first example embodiment. As shown inFIG.19, the curved portion60a3is a concave surface recessed toward the bottom surface60b. The curved portion60a3has a curved shape (arch shape) curved to be recessed toward the bottom surface60b(−Z direction) in a given cross section parallel to the YZ plane. In the given cross section parallel to the YZ plane, the distance from the bottom surface60bto the curved portion60a3is the smallest at the center of the curved portion60a3in a direction parallel to the Y direction (hereinafter, referred to simply as the center of the curved portion60a3).

The at least one curved portion60a3extends along the X direction. The overall shape of the at least one curved portion60a3is a semicylindrical surface formed by moving the curved shape shown inFIG.19along the X direction. The insulating layer62of the support member60has a cross-sectional shape such that the curved portion60a3is formed in the opposed surface60a. Specifically, the insulating layer62has a cross-sectional shape recessed in the −Z direction in a given cross section parallel to the YZ plane.

A portion of the curved portion60a3from an edge at the end of the curved portion60a3in the Y direction to the center of the curved portion60a3will be referred to as a first inclined surface and be denoted by the reference symbol SL11. A portion of the curved portion60a3from an edge at the end of the curved portion60a3in the −Y direction to the center of the curved portion60a3will be referred to as a second inclined surface and be denoted by the reference symbol SL12. Both the first and second inclined surfaces SL11and SL12are inclined relative to the reference plane, i.e., the bottom surface60b. In the present example embodiment, the entire MR element330is located on the first inclined surface SL11or the second inclined surface SL12.FIG.19shows how the MR element30is located on the first inclined surface SL11.

The MR element330has a shape that is long in the X direction. The MR element330has a rectangular planar shape.

The MR element330may be a spin-valve MR element or an AMR element. The following description will be given by using the case where the MR element330is a spin-valve MR element as an example. Like the MR element30shown inFIG.6according to the first example embodiment, the MR element330includes an underlayer31, a magnetization pinned layer32, a spacer layer33, a free layer34, and a cap layer35. The free layer34has magnetic shape anisotropy where the direction of the easy axis of magnetization is parallel to the X direction.

Next, the MR element330will be described in more detail with reference toFIG.20.FIG.20is an explanatory diagram for describing the shape of the free layer34.FIG.20is an enlarged view of a part of the cross section shown inFIG.19. InFIG.20, the underlayer31and the cap layer35of the MR element330are omitted.

As described in the first example embodiment, the free layer34has a first surface34a, a second surface34b, and an outer peripheral surface. The first surface34ahas a first edge Ed1and a second edge Ed2located at both lateral ends of the first surface34a. In the present example embodiment, both the first and second edges Ed1and Ed2are located above the first inclined surface SL11of the curved portion60a3or both the first and second edges Ed1and Ed2are located above the second inclined surface SL12of the curved portion60a3. The distance from the bottom surface60bof the support member60to the first edge Ed1is greater than the distance from the bottom surface60bof the support member60to the second edge Ed2.

The relationship between the inclination angle θ1at the first edge Ed1, the inclination angle θ2at the second edge Ed2, and the inclination angle θp at the predetermined point P in a given cross section S intersecting the free layer34and perpendicular to the longitudinal direction of the first surface34a(direction parallel to the X direction) is the same as that in the first example embodiment. The relationship between the thickness T1at the first edge Ed1, the thickness T2at the second edge Ed2, and the thickness Tp at the predetermined point P in the given cross section S is also the same as that in the first example embodiment. For the sake of convenience, an imaginary surface is assumed by extending the second surface34balong the curved portion60a3, and the thickness T1is defined as the distance between the first surface34aand the imaginary surface in the direction perpendicular to the first surface34a.

Like the MR element130according to the second example embodiment, the MR element330may be located across the first inclined surface SL11and the second inclined surface SL12. The configuration, operation and effects of the present example embodiment are otherwise the same as those of the first or second example embodiment.

The technology is not limited to the foregoing example embodiments, and various modifications may be made thereto. For example, the number and arrangement of MR elements and the number and arrangement of curved portions are not limited to those described in the example embodiments, and may be freely chosen as long as the requirements set forth in the claims are satisfied.

The MR elements according to the technology may be located on a flat surface parallel to the reference plane as long as the requirement that the thickness T1at the first edge Ed1be smaller than the thickness Tp at a predetermined point P in a given cross section S is satisfied. The MR element including the free layer34having such a thickness T can be implemented, for example, by so-called wedge deposition capable of forming an inclined film thickness.

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 most example embodiments.