JP2009162499A - Magnetometric sensor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a magnetometric sensor, especially, for lowering magnetic sensitivity furthermore than hitherto to a magnetic field from a direction perpendicular to a sensitivity axial direction, while keeping excellently magnetic sensitivity to the magnetic field in the sensitivity axial direction. <P>SOLUTION: Magnetic resistance effect elements 2, 3 are equipped with an element part 12 having an elongate shape wherein the element length L1 is formed longer than the element width W1, and a permanent magnet layer 19 for supplying a bias magnetic field to the element part 12. The element part 12 includes a fixed magnetic layer having a fixed magnetization direction, and a free magnetic layer whose magnetization direction is changed by receiving an external magnetic field, laminated on the fixed magnetic layer through a non-magnetic layer, and a fixed magnetization direction (P-direction) of the fixed magnetic layer is faced to the element length direction. A permanent magnet layer 19 is arranged on the side in the element width direction of the element part 12, and the bias magnetic field is supplied to the element part 12 from the element width direction. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a magnetic sensor using a magnetoresistive effect element used as, for example, a geomagnetic sensor.

  A magnetic sensor using a magnetoresistive effect element can be used as a geomagnetic sensor that detects geomagnetism incorporated in a portable device such as a mobile phone.

  FIG. 11 is a plan view of a magnetoresistive effect element provided in the magnetic sensor described in Patent Document 1. FIG. The magnetoresistive effect element 50 includes a plurality of element portions 51 and a permanent magnet layer 52 that connects between end portions of the element portions 51.

  The element width 51 of each element portion 51 is an elongated shape that is shorter than the element length L5 and extends in the X direction in the drawing, and each element portion 51 is arranged with a gap in the element width direction. The element unit 51 includes a pinned magnetic layer and a free magnetic layer stacked on the pinned magnetic layer via a nonmagnetic layer. The fixed magnetization direction (P direction) of the fixed magnetic layer is oriented in the element width direction.

  A bias magnetic field is supplied from the permanent magnet layers 52 disposed on both sides of each element portion 51 in the longitudinal direction toward the element length direction.

  FIG. 12A is a graph of a resistance change rate curve when a magnetic field is applied in the element width direction (sensitivity axis direction) to the element unit 51 alone without forming the permanent magnet layer 52. is there. In FIG. 12B, the magnetic field is applied to the element portion 51 alone without forming the permanent magnet layer 52 in the element length direction (direction perpendicular to the sensitivity axis direction, hereinafter referred to as “orthogonal direction”). It is a graph of the resistance change rate curve when it is made to act. That is, FIG. 12A and FIG. 12B both measure the resistance change without supplying a bias magnetic field to the element unit 51.

  FIG. 13A shows a configuration in which the permanent magnet layer 52 is provided on both sides of the element portion 51 in the element length direction, and a bias magnetic field is applied to the element portion 51 in the element length direction (orthogonal direction). It is a graph of a resistance change rate curve when a magnetic field is applied in the element width direction (sensitivity axis direction). FIG. 13B shows that the permanent magnet layer 52 is provided on both sides of the element portion 51 and a bias magnetic field is applied to the element portion 51 in the element length direction (orthogonal direction). It is a graph of a resistance change rate curve when a magnetic field is applied toward (orthogonal direction).

  In the form of FIG. 11, the element width direction (sensitivity axis direction) in which the fixed magnetization direction (P direction) of the fixed magnetic layer faces is the hard magnetization axis direction, and a bias magnetic field is supplied as shown in FIG. A resistance change rate curve that is relatively gently inclined with respect to a magnetic field directed in the element width direction (sensitivity axis direction) without being shown. On the other hand, since the element length direction (orthogonal direction) is the easy magnetization axis direction, a steep resistance change rate curve with respect to the magnetic field directed in the element length direction (orthogonal direction) as shown in FIG. Show. As shown in FIG. 12B, a substantially V-shaped resistance change rate curve is shown with respect to the magnetic field.

  When the bias magnetic field is supplied, as shown in FIG. 13A, the magnetic field directed in the element width direction (sensitivity axis direction) is more gradual than the case where the bias magnetic field in FIG. 12A is not supplied. It becomes the resistance change rate curve of the slope. Also, as shown in FIG. 13B, by supplying a bias magnetic field, the bottom top D of the substantially V-shaped resistance change rate curve shifts from the state in which the bias magnetic field in FIG. 12B is not supplied.

  FIG. 13A shows the detected magnetic field range. The detection magnetic field range is defined in a linear region (magnetic sensitivity region) in which the resistance change rate varies with respect to the magnetic field from the element width direction (sensitivity axis direction). For example, when a magnetic sensor is used as a geomagnetic sensor, the geomagnetism is as weak as a comma number Oe. Considering only this geomagnetism, the detection magnetic field range may be a very narrow range having a comma number Oe. In practice, however, the detection magnetic field can be appropriately detected even when a disturbance magnetic field is generated in the apparatus. The range is defined to be about several Oe to several tens Oe.

  At this time, when the disturbance magnetic field acts from the element length direction (orthogonal direction), as shown in FIG. 13B, the disturbance magnetic field is within a magnetic field range showing a substantially V-shaped resistance change rate curve. Originally, a large resistance change is exhibited with respect to the magnetic field in the element length direction (orthogonal direction) which is desired to have no magnetic sensitivity. Therefore, there is a problem that the detection accuracy cannot be improved.

  In addition, when a rotating magnetic field is applied, it is ideal to draw a substantially Sin wave output curve with respect to the rotating magnetic field, but as shown in FIG. 13B, the detected magnetic field is applied in the element length direction (orthogonal direction). When the effect is applied, the resistance change rate portions of the substantially V-shaped portion are added together, resulting in a deviation from the ideal Sin wave.

  It is considered that the above problem can be solved by increasing the bias magnetic field supplied to the element portion 51 and increasing the shift amount of the bottom top portion D of the substantially V-shaped resistance change rate curve shown in FIG. .

However, if the bias magnetic field is increased, the slope of the resistance change rate curve with respect to the magnetic field in the element width direction (sensitivity axis direction) shown in FIG. The detection accuracy could not be improved.
JP 2005-183614 A

  Therefore, the present invention is for solving the above-described conventional problems, and in particular, the magnetic field from the direction orthogonal to the sensitivity axis direction is more than conventional, while maintaining good magnetic sensitivity to the magnetic field in the sensitivity axis direction. An object of the present invention is to provide a magnetic sensor capable of reducing the magnetic sensitivity.

The present invention is a magnetic sensor comprising a magnetoresistive effect element,
The magnetoresistive element includes an elongated element portion having an element length L1 formed longer than an element width W1, and a permanent magnet layer that supplies a bias magnetic field to the element portion. A pinned magnetic layer whose magnetization direction is fixed, and a free magnetic layer which is laminated on the pinned magnetic layer via a nonmagnetic layer and changes the magnetization direction upon receiving an external magnetic field. The fixed magnetization direction is oriented in the element length direction,
The permanent magnet layer is disposed on a side of the element portion in the element width direction, and a bias magnetic field is supplied to the element portion from the element width direction.

  In the present invention, the fixed magnetization direction (P direction) of the fixed magnetic layer is the easy magnetization axis direction. On the other hand, the element width direction is the hard axis direction (see FIG. 1A). That is, in the present invention, the fixed magnetization direction (P direction), the magnetization easy axis direction (EA direction), the element length direction, and the sensitivity axis direction all indicate the same direction, and the element width direction and the magnetization difficult axis direction (HA) Direction) and the direction perpendicular to the sensitivity axis all refer to the same direction. In the following description, directions are mainly indicated by the notation of element length direction (sensitivity axis direction) and element width direction (orthogonal direction).

  FIG. 7A shows a resistance change rate curve when a magnetic field is applied to the element portion of the present invention from the element length direction (sensitivity axis direction).

  FIG. 7B shows a resistance change rate curve when a magnetic field is applied to the element portion of the present invention from the element width direction (orthogonal direction). 7A and 7B show resistance change rate curves of the element unit alone without supplying a bias magnetic field to the element unit.

  As shown in FIG. 7A, since the fixed magnetization direction (P direction) of the fixed magnetic layer is the easy magnetization axis direction, when a magnetic field is applied from the element length direction (sensitivity axis direction), FIG. Compared to the case where the fixed magnetization direction is the hard axis direction as in the conventional case shown in a), the resistance change rate curve has a steep slope. Further, as shown in FIG. 7A, a slight hysteresis occurs, but the hysteresis can be sufficiently reduced by supplying a bias magnetic field.

  Further, as shown in FIG. 7B, when a magnetic field is applied from the element width direction (orthogonal direction), a resistance change rate curve having a substantially V-shaped inclination is shown as in the conventional case shown in FIG. . However, in the present invention, since the element width direction is the hard axis direction, the slope of the resistance change rate curve can be made gentler than in the conventional case shown in FIG.

  FIG. 8A shows a configuration in which a permanent magnetic layer is provided on the side of the element portion of the present invention in the element width direction (orthogonal direction: HA direction) and a bias magnetic field is supplied from the element width direction (orthogonal direction). A resistance change rate curve when a magnetic field is applied from the element length direction (sensitivity axis direction) is shown.

  FIG. 8B shows a configuration in which a permanent magnetic layer is provided on the side of the element portion of the present invention in the element width direction (orthogonal direction: HA direction) and a bias magnetic field is supplied from the element width direction (orthogonal direction). The resistance change rate curve when a magnetic field is applied to the element portion of the present invention from the element width direction (orthogonal direction) is shown.

  In the present invention, as described with reference to FIG. 7A, the slope of the resistance change rate curve with respect to the magnetic field from the element length direction (sensitivity axis direction) without a permanent magnet layer is steep. Therefore, as shown in FIG. 8A, the bias magnetic field supplied from the permanent magnet layer to the element portion can be made stronger than before in order to make the slope of the resistance change rate curve with respect to the magnetic field gentle. Further, as described above, the hysteresis can be sufficiently reduced by the sufficient bias magnetic field. As a result, as shown in FIG. 8B, when a magnetic field is applied from the element width direction (orthogonal direction), a bias magnetic field is not supplied at the bottom top E of the substantially V-shaped resistance change rate curve (FIG. 7). The amount of shift from (b)) (the magnitude of the magnetic field required to reach the bottom top E) can be made larger than before.

  As described above, according to the present invention, the rate of change in resistance that is substantially V-shaped with respect to the magnetic field from the element width direction (orthogonal direction) while maintaining good magnetic sensitivity to the magnetic field from the element length direction (sensitivity axis direction). Since the slope of the curve can be reduced and the amount of shift of the bottom top E of the portion where the resistance changes to a substantially V shape can be increased, the magnetic sensitivity can be reduced.

  In the present invention, when an external magnetic field acts on the element portion from the element width direction, the magnitude of the bias magnetic field is adjusted so that a predetermined magnetic field range from the non-magnetic state to both directions in the element width direction becomes a dead magnetic field range. It is preferable. In the present invention, as described above, with respect to the magnetic field from the element width direction (orthogonal direction), it is possible to increase the shift amount of the bottom top E of the portion where the resistance changes to a substantially V shape. Can be prepared. In the insensitive magnetic field range, even if a magnetic field acts from the element width direction (orthogonal direction), the resistance change is zero or very small, and the fluctuation of the resistance change rate can be reduced, and the magnetic sensitivity is not substantially obtained. For example, the maximum rate of change in resistance per Oe in the dead magnetic field range is as small as about 0% to 0.03% / Oe.

  In the present invention, the bias is set such that the dead magnetic field range is at least a detection magnetic field range defined for a magnetic field from a direction parallel to the sensitivity axis direction with the element length direction as the sensitivity axis direction. It is preferable that the magnitude of the magnetic field is adjusted.

  For example, when a disturbance magnetic field with a magnitude within the detection magnetic field range acts from the element width direction (orthogonal direction), or when a rotating magnetic field within the detection magnetic field range acts on the magnetic field from the element width direction (orthogonal direction) Therefore, the magnetic sensitivity can be sufficiently reduced, so that the detection accuracy can be improved as compared with the conventional case.

  Moreover, in this invention, the said detection magnetic field range can be applied suitably for the structure which is the range of +/- 5Oe-+/- 20Oe.

In the present invention, a plurality of the element portions are arranged at intervals in the element width direction, and the end portions of each element portion are connected and formed in a meander shape.
The permanent magnet layer can be arranged at least outside the element portion located on both sides in the element width direction.

  Moreover, it is preferable that the said permanent magnet layer is each arrange | positioned at the both sides of the element width direction of each element part. Thereby, a bias magnetic field can be appropriately supplied to each element part. Since the bias magnetic field is integrated as the inner pattern is further increased, it is more desirable to increase the width of the outermost permanent magnet layer pattern in order to uniformly apply the magnetic field to the elements.

In the present invention, a soft magnetic body extending in the width direction of the element portion may be disposed in the element length direction of the element portion with a gap from the element portion.
In the present invention, it is preferable that the permanent magnetic layer and the element portion are not in contact with each other.

  According to the magnetic sensor of the present invention, the magnetic sensitivity with respect to the magnetic field from the direction of the sensitivity axis can be reduced while the magnetic sensitivity to the magnetic field from the direction orthogonal to the sensitivity axis is reduced while maintaining good magnetic sensitivity to the magnetic field from the sensitivity axis direction. Is possible.

  1A and 1B are views showing a part of a magnetoresistive element, in particular, a magnetoresistive effect element according to the first embodiment (FIG. 1A is a partial plan view, and FIG. 1B is a height direction along the line A-A in FIG. FIG. 2 is a plan view showing a part of the magnetoresistive element of the magnetic sensor in the second embodiment, and FIG. 3 is a magnetic sensor in the third embodiment. FIG. 4 is a diagram for explaining the relationship between the fixed magnetization direction of the fixed magnetic layer of the magnetoresistive effect element, the magnetization direction of the free magnetic layer, and the electric resistance value. 5 is a cross-sectional view showing a cut surface when the magnetoresistive element is cut from the film thickness direction, and FIG. 6 is a circuit diagram of the magnetic sensor of the present embodiment.

  The magnetic sensor 1 provided with the magnetoresistive effect element in this embodiment is used as a geomagnetic sensor mounted on a portable device such as a cellular phone.

  As shown in FIG. 6, the magnetic sensor 1 includes a sensor unit 6 in which magnetoresistance effect elements 2 and 3 and fixed resistance elements 4 and 5 are bridge-connected, and an input terminal 7 electrically connected to the sensor unit 6. And an integrated circuit (IC) 11 having a ground terminal 8, a differential amplifier 9, an external output terminal 10, and the like.

  As shown in FIG. 1, the magnetoresistive effect elements 2 and 3 have a plurality of element portions 12 which are formed in an element length L1 longer than the element width W1 and are elongated in the Y direction in the figure, and are orthogonal to the Y direction. They are arranged in parallel in the X direction at a predetermined interval, and the end portions of the respective element portions 12 are electrically connected by the connection electrode portions 13 to form a meander shape. An electrode portion 15 connected to the input terminal 7, the ground terminal 8, and the output extraction portion 14 (see FIG. 6) is connected to one of the element portions 12 at both ends formed in a meander shape. The connection electrode portion 13 and the electrode portion 15 are made of a nonmagnetic conductive material such as Al, Ta, or Au. In this embodiment, since the electrode parts 13 and 15 which connect between the element parts 12 can be formed with a material whose resistance is sufficiently smaller than that of the element parts 12, compared with the conventional case where the element parts 12 are connected by a permanent magnet layer. Parasitic resistance can be reduced. The connection electrode portion 13 and the electrode portion 15 are formed by sputtering or plating.

  All the element portions 12 constituting the magnetoresistive effect elements 2 and 3 have the same laminated structure shown in FIG. FIG. 5 shows a cut surface cut in the film thickness direction from the direction parallel to the element length L1.

  The element portion 12 is formed by laminating an antiferromagnetic layer 33, a pinned magnetic layer 34, a nonmagnetic layer 35, and a free magnetic layer 36 in this order, and the surface of the free magnetic layer 36 is covered with a protective layer 37. Yes. The element unit 12 is formed by sputtering, for example.

  The antiferromagnetic layer 33 is made of an antiferromagnetic material such as an Ir—Mn alloy (iridium-manganese alloy). The pinned magnetic layer 34 is formed of a soft magnetic material such as a Co—Fe alloy (cobalt-iron alloy). The nonmagnetic layer 35 is made of Cu (copper) or the like. The free magnetic layer 36 is made of a soft magnetic material such as a Ni—Fe alloy (nickel-iron alloy). The protective layer 37 is a Ta (tantalum) layer. In the above configuration, the nonmagnetic layer 35 is a giant magnetoresistive element (GMR element) formed of a nonmagnetic conductive material such as Cu, but a tunnel type magnetoresistive element (TMR element) formed of an insulating material such as Al2O3. ). In addition, the stacked configuration of the element unit 12 illustrated in FIG. 5 is an example, and another stacked configuration may be used. For example, the free magnetic layer 36, the nonmagnetic layer 35, the pinned magnetic layer 34, the antiferromagnetic layer 33, and the protective layer 37 may be stacked in this order from the bottom.

  In the element unit 12, the magnetization direction of the pinned magnetic layer 34 is fixed by antiferromagnetic coupling between the antiferromagnetic layer 33 and the pinned magnetic layer 34. As shown in FIGS. 1 and 5, the pinned magnetization direction (P direction) of the pinned magnetic layer 34 faces the element length direction (Y direction). That is, the fixed magnetization direction (P direction) of the fixed magnetic layer 34 is the longitudinal direction of the element portion 12.

  As shown in FIG. 1, permanent magnet layers 19 are arranged on both sides of each element portion 12 in the element width direction (X direction) with a space therebetween. The permanent magnet layer 19 is formed with a width dimension W2 in the same direction as the element width direction (X direction) and a length dimension L2 in the element length direction (Y direction). The length dimension L2 is larger than the width dimension W2, and the permanent magnet layer 19 has an elongated shape extending in the Y direction in the figure.

  Although not shown, an insulating layer made of Al 2 O 3 or SiO 2 is interposed between the element portion 12 and the permanent magnet layer 19. The permanent magnet layer 19 is made of a hard magnetic material such as CoPt or CoPtCr. The permanent magnet layer 19 is formed by sputtering, for example.

  In the present embodiment, the bias magnetic field supplied from the permanent magnet layer 19 to the element unit 12 can be made larger than in the conventional case. Specifically, the bias magnetic field can be about 40 to 60 Oe. The bias magnetic field can be increased by increasing the thickness T10 of the permanent magnet layer 19 or increasing the residual magnetization Mr of the permanent magnet layer 19.

  A bias magnetic field is supplied from the permanent magnet layer 19 to the element portion 12 from the element width direction (X direction). As a result, the magnetization direction (F direction) of the free magnetic layer 36 is oriented in the element width direction (X direction). The magnetization direction (F direction) of the free magnetic layer 36 can be changed by an external magnetic field.

  As shown in FIG. 4, the external magnetic field Y1 acts from the same direction as the fixed magnetization direction (P direction) of the fixed magnetic layer 34, and the magnetization direction (F direction) of the free magnetic layer 36 faces the external magnetic field Y1 direction. Then, the fixed magnetization direction (P direction) of the fixed magnetic layer 34 and the magnetization direction (F direction) of the free magnetic layer 36 approach each other, and the electric resistance value decreases.

  On the other hand, as shown in FIG. 4, the external magnetic field Y2 acts from the direction opposite to the fixed magnetization direction (P direction) of the fixed magnetic layer 34, and the magnetization direction (F direction) of the free magnetic layer 36 changes to the external magnetic field Y2 direction. , The fixed magnetization direction (P direction) of the fixed magnetic layer 34 and the magnetization direction (F direction) of the free magnetic layer 36 approach antiparallel, and the electrical resistance value increases.

Each dimension will be described.
The element width W1 of the element portion 12 constituting the magnetoresistive effect elements 2 and 3 is in the range of 2 to 8 μm in order to cause the bias magnetic field to act on the magnetoresistive film efficiently (see FIG. 1A). The element length L1 of the element unit 12 is in the range of 50 to 100 μm (see FIG. 1A). The aspect ratio (element length L1 / element width W1) is set to 10 or more, and the anisotropic magnetic field (Hk) is increased by utilizing shape anisotropy. Moreover, the film thickness T1 of the element portion 12 is in the range of 200 to 300 mm (see FIG. 1B). Moreover, the width dimension W2 of the permanent magnet layer 19 is 3-10 micrometers (refer Fig.1 (a)). The length L2 of the permanent magnet layer 19 is preferably larger than the element width length L1. (Preferably, the protrusion amount is preferably 20 μm or more on one side in order to improve the intra-element bias magnetic field distribution) (see FIG. 1A). The film thickness T10 of the permanent magnet layer 19 is 200 to 1000 mm (see FIG. 1B). The permanent magnet layer 19 has a residual magnetization Mr of 0.7 to 1.5 T (Tesla).

  A distance T2 in the element width direction (X direction) between the element portion 12 and the permanent magnet layer 19 is 0 to 5 μm (see FIG. 1B).

  In FIG. 1, the width W2 of the permanent magnet layer 19 is all the same, but the bias magnetic field is integrated as the inner pattern is formed. Therefore, the bias magnetic field is uniformly applied to each element portion 12. Therefore, it is more desirable to make the width W3 of the outermost permanent magnet layer 19 wider as shown by the dotted line in FIG. Further, the width dimension of the permanent magnet layer 19 may be gradually increased from the innermost permanent magnet layer 19 toward the outermost permanent magnet layer 19.

  In the embodiment of FIG. 2, unlike FIG. 1, a pair of permanent magnet layers 19 is disposed only outside the element portion 12 located on both sides in the element width direction. Even if the permanent magnet layers 19 are not arranged on both sides of each element portion 12 as shown in FIG. 1, the arrangement as shown in FIG. 2 may be adopted as long as a large bias magnetic field can be supplied to the entire element portion 12.

  In the present embodiment, the fixed magnetization direction (P direction) of the fixed magnetic layer 34 faces the element length direction (Y direction) which is the easy axis direction. On the other hand, the element width direction (X direction) is the hard axis direction (see FIG. 1A). That is, in this embodiment, the fixed magnetization direction (P direction), the magnetization easy axis direction (EA direction), the element length direction, and the sensitivity axis direction all indicate the same direction, and the element width direction and the magnetization difficult axis direction ( (HA direction) and the direction orthogonal to the sensitivity axis all indicate the same direction. In the following description, directions are mainly indicated by the notation of the element length direction (Y direction; sensitivity axis direction) and the element width direction (X direction; orthogonal direction).

  Thus, since the pinned magnetization direction (P direction) of the pinned magnetic layer 34 faces the element length direction (Y direction; sensitivity axis direction), the permanent magnet layer 19 is not provided, and the element unit 12 alone is provided. On the other hand, when a magnetic field is applied from the element length direction (Y direction; sensitivity axis direction), the resistance change rate curve has a steep slope as shown in FIG. Further, as shown in FIG. 7A, a slight hysteresis occurs, but the hysteresis can be sufficiently reduced by supplying a bias magnetic field.

  FIG. 7B shows a resistance change rate curve when a magnetic field is applied from the element width direction (X direction; orthogonal axis direction) to the element unit 12 alone without providing the permanent magnet layer 19. As shown in FIG. 7B, when a magnetic field is applied from the element width direction (orthogonal direction), a resistance change rate curve having a substantially V-shaped gradient is shown. However, in this embodiment, since the element width direction (X direction; orthogonal axis direction) is the hard magnetization axis direction, the slope of the resistance change rate curve can be moderated.

  FIG. 8A shows a configuration in which a permanent magnetic layer 19 is provided on the side of the element width direction of the element portion 12 and a bias magnetic field is supplied from the element width direction (X direction; orthogonal direction) as shown in FIG. On the other hand, a resistance change rate curve when a magnetic field is applied to the element portion 12 from the element length direction (Y direction; sensitivity axis direction) is shown.

  In FIG. 8B, as shown in FIG. 1, a permanent magnet layer 19 is provided on the side of the element portion 12 in the element width direction, and a bias magnetic field is supplied from the element width direction (X direction; orthogonal direction). On the other hand, a resistance change rate curve when a magnetic field is applied to the element portion 12 from the element width direction (X direction; orthogonal direction) is shown.

  As described with reference to FIG. 7A, the slope of the resistance change rate curve with respect to the magnetic field from the element length direction (Y direction; sensitivity axis direction) without the permanent magnet layer 19 is steep. Therefore, as shown in FIG. 8A, the bias magnetic field supplied from the permanent magnet layer 19 to the element portion 12 can be made stronger than before in order to make the slope of the resistance change rate curve with respect to the magnetic field gentle.

  As a result, as shown in FIG. 8B, when a magnetic field is applied from the element width direction (X direction; orthogonal direction), a bias magnetic field is not supplied at the bottom top E of the substantially V-shaped resistance change rate curve. The shift amount (the magnitude of the magnetic field required to reach the bottom top E) from (FIG. 7 (b)) can be made larger than before.

  As described above, in the present embodiment, the magnetic sensitivity from the element width direction (X direction; orthogonal direction) is substantially maintained while maintaining good magnetic sensitivity to the magnetic field from the element length direction (Y direction; sensitivity axis direction). The inclination of the V-shaped resistance change rate curve can be reduced, and the shift amount of the bottom top E of the portion where the resistance changes to a substantially V-shape can be increased, so that the magnetic sensitivity can be lowered.

  In the present embodiment, as shown in FIG. 8B, a predetermined magnetic field range in both the element width direction (X direction; orthogonal direction) from the no magnetic field state (zero external magnetic field) is the dead magnetic field range. . As described above, with respect to the magnetic field from the element width direction (X direction; orthogonal direction), the shift amount of the bottom top E of the portion where the resistance is changed to a substantially V shape can be increased. Therefore, a predetermined magnetic field range in both directions in the element width direction (X direction; orthogonal direction) from the non-magnetic field state can be set as a dead magnetic field range. In the insensitive magnetic field range, even if a magnetic field acts from the element width direction (X direction; orthogonal direction), the resistance change is zero or very small, and the fluctuation of the resistance change rate can be reduced, and the magnetic sensitivity is not substantially obtained. It is. For example, the rate of change of the resistance change rate (MR ratio) in the dead magnetic field range is as small as about 0% to 0.4%. The variation rate of the resistance change rate within the dead magnetic field range is determined by (maximum resistance change rate within the dead magnetic field range) − (minimum resistance change rate within the dead magnetic field range).

  7 and 8, the vertical axis represents the resistance change rate (MR ratio), but the resistance value R may be used. In this case, the variation rate of the resistance value in the dead magnetic field range is as small as about 0% to 0.4%. The variation rate of the resistance value in the dead magnetic field range is determined by [(maximum resistance value in the dead magnetic field range) − (minimum resistance value in the dead magnetic field range)].

  For example, the offset correction can be performed on the circuit side using the resistance change rate (MR ratio) or the resistance value in the dead magnetic field range as a reference value.

    In addition, the dead magnetic field range shown in FIG. 8B is preferably a magnetic field range that is equal to or greater than the detection magnetic field range defined for the magnetic field from the direction parallel to the element length direction (Y direction; sensitivity axis direction). . The detection magnetic field range is defined by a low magnetic field range of ± several Oe to ± tens of Oe, and is suitable for a configuration of ± 5 to ± 20 Oe. The detection magnetic field range is a linear region in which the resistance change rate (MR ratio) or the resistance value shown in FIG. 8A fluctuates substantially linearly with respect to the magnetic field from the element length direction (Y direction; sensitivity axis direction). In the magnetic sensitivity region). [Sensitivity in orthogonal direction (insensitive magnetic field range) / Sensitivity in sensitivity axis direction (detection magnetic field range)] × 100 (%) = 10% or less is preferable.

  By adjusting the magnitude of the bias magnetic field so that the dead magnetic field range is greater than or equal to the detection magnetic field range, for example, a disturbance magnetic field having a magnitude within the detection magnetic field range can be detected in the element width direction (X direction; orthogonal). When acting from the element direction, the magnetic field from the element width direction (X direction; orthogonal direction) has substantially no magnetic sensitivity, and therefore acts from the element length direction (Y direction; sensitivity axis direction). Detection accuracy for geomagnetism can be improved.

  The dead field range can be adjusted by adjusting the bias magnetic field supplied to the element section. The magnitude of the bias magnetic field is substantially the same as the shift amount of the bottom top E of the portion where the resistance changes to a substantially V shape. Therefore, by making the bias magnetic field larger than the maximum magnetic field (absolute value) in the detection magnetic field range (specifically, the bias magnetic field is about 5 to 15 times the maximum magnetic field in the detection magnetic field range), The bottom top E shown in FIG. 8B can be shifted so as to be out of the detection magnetic field range, and the dead magnetic field range can be appropriately adjusted to a magnetic field range that is equal to or greater than the detection magnetic field range. . The configuration of the magnetoresistive elements 2 and 3 shown in FIG. 1 is for detecting geomagnetism from the Y direction. In order to be able to detect the geomagnetism acting from the X and Z directions, the magnetoresistive elements 2 and 3 in which the fixed magnetization direction (P direction) of the fixed magnetic layer 34 is directed to the detection direction of the geomagnetism are used. Configure the sensor.

  The magnetic sensor 1 including the magnetoresistive effect elements 2 and 3 shown in FIG. 1 can be applied to uses other than the geomagnetic sensor. For example, the present invention can be applied to an application for detecting a rotating magnetic field in which a detection magnetic field range is a low magnetic field range of ± several mOe to ± 5 Oe. At this time, for the magnetic field from the element width direction (X direction; orthogonal direction), the magnetic sensitivity can be reduced appropriately, so that the output waveform can be made closer to the Sin wave more effectively than in the past. It is.

  Although only one element portion 12 constituting the magnetoresistive effect elements 2 and 3 may be provided, it is preferable to provide a plurality of the magnetoresistive effect elements 2 and 3 in a meander shape because the element resistance can be increased and the power consumption can be reduced.

  The magnetoresistive effect elements 2 and 3 and the fixed resistance elements 4 and 5 may be provided one by one. However, as shown in FIG. 6, a bridge circuit is formed, and the output obtained from the output extraction unit 14 is supplied to the differential amplifier 9. By using differential output, the output value can be increased and high-precision magnetic field detection can be performed.

  Further, by making the element portion 12 and the permanent magnet layer 19 non-contact as shown in FIGS. 1 and 2, the parasitic resistance other than the element resistance due to the element portion 12 can be reduced.

  In another embodiment of FIG. 3, meander-shaped magnetoresistive elements 2 and 3 similar to those of the embodiment shown in FIG. 1 are formed in plan view, and the element length direction (Y direction) of the element portion 12 is formed. Soft magnetic bodies 18 that extend long in the X direction are disposed at upper positions on both sides. The length L3 of the soft magnetic body 18 is preferably formed longer than the interval T4 between the element portions 12 positioned on the outermost side constituting the magnetoresistive effect elements 2 and 3. The arrangement of the soft magnetic material 18 can appropriately shield the external magnetic field from the X direction, can apparently widen the dead magnetic field range, and can improve the detection accuracy for the magnetic field from the sensitivity axis direction. For example, the soft magnetic body 18 is disposed on an insulating layer (not shown) that covers the magnetoresistive elements 2 and 3. The soft magnetic body 18 is made of NiFe, CoFe, CoFeSiB, CoZrNb, or the like.

  The magnetoresistive effect element (Example) shown in FIG. 1 was formed. Six element portions 12 were formed to have a meander shape. The element portion 12 has an element width W1 of 2 μm, an element length L1 of 50 μm, a film thickness T1 of 270 mm, a permanent magnet layer 19 (CoPt) width dimension W2 of 5 μm, a length dimension L2 of 90 μm, and a film thickness T10 of 200 mm. The distance T2 between the element part 12 and the permanent magnet layer 19 was set to 0 μm. The fixed magnetic layer 34 was fixedly magnetized in the element length direction (Y direction; sensitivity axis direction) by annealing in a magnetic field. The bias magnetic field supplied from the permanent magnet layer 19 to the element unit 12 was 45 Oe.

  The resistance change rate (MR ratio) of the magnetoresistive effect elements 2 and 3 was examined by applying an external magnetic field in the sensitivity axis direction. Further, the resistance change rate (MR ratio) of the magnetoresistive effect elements 2 and 3 was examined by applying an external magnetic field in a direction orthogonal to the sensitivity axis direction.

  In the experiment, a hysteresis loop (major loop) was measured by applying an external magnetic field of ± 1000 Oe, and a minor loop was measured by applying an external magnetic field of ± 6 Oe, which is the detected magnetic field range. The resistance change rate curve in the minor loop is indicated by a bold line.

  Next, the magnetoresistive effect element (conventional example) shown in FIG. 11 was formed. Six element portions 51 were formed to have a meander shape. The element portion 51 has an element width W5 of 4 μm, an element length L5 of 16 μm, a film thickness of 250 mm, a permanent magnet layer 52 (CoPt) width dimension W6 of 8 μm, and a film thickness of 200 mm. The fixed magnetic layer 34 was fixedly magnetized in the element width direction (sensitivity axis direction) by annealing in a magnetic field. The bias magnetic field supplied from the permanent magnet layer 52 to the element unit 51 was 15 Oe.

  The resistance change rate (MR ratio) of the magnetoresistive effect elements 2 and 3 was examined by applying an external magnetic field in the sensitivity axis direction. Further, the resistance change rate (MR ratio) of the magnetoresistive effect elements 2 and 3 was examined by applying an external magnetic field in a direction orthogonal to the sensitivity axis direction.

  In the experiment, a hysteresis loop (major loop) was measured by applying an external magnetic field of ± 1000 Oe, and a minor loop was measured by applying an external magnetic field of ± 6 Oe, which is the detected magnetic field range. The resistance change rate curve in the minor loop is indicated by a bold line.

  In the example and the conventional example, the bias magnetic field supplied to the element unit 12 is adjusted so that the sensitivity is almost the same when an external magnetic field of ± 6 Oe is applied from the sensitivity axis direction. That is, as shown in FIGS. 9 and 10, when viewed in the detected magnetic field range of ± 6 Oe, the resistance change rate curve with respect to the magnetic field from the sensitivity axis direction has substantially the same slope in both the example and the conventional example. It was adjusted.

  In this example, it was found that when an external magnetic field of ± 6 Oe was applied from the direction orthogonal to the sensitivity axis direction, the slope of the resistance change rate curve was very small and the magnetic sensitivity was appropriately reduced.

  On the other hand, in the conventional example of FIG. 10, when an external magnetic field of ± 6 Oe is applied from the direction orthogonal to the sensitivity axis direction, the slope of the resistance change rate curve becomes larger than in the example of FIG. It turned out that it cannot be lowered.

The figure which shows the part of especially the magnetoresistive effect element of the magnetic sensor in 1st Embodiment ((a) is a partial top view, (b) is a height direction (Z direction shown in figure) along the AA line of (a). ) And a partial cross-sectional view as seen from the direction of the arrow), The top view which shows the part of especially the magnetoresistive effect element of the magnetic sensor in 2nd Embodiment, The top view which shows the part of especially the magnetoresistive effect element of the magnetic sensor in 3rd Embodiment, The figure for demonstrating the relationship between the fixed magnetization direction of the fixed magnetic layer of a magnetoresistive effect element, the magnetization direction of a free magnetic layer, and an electrical resistance value, Sectional drawing which shows the cut surface at the time of cut | disconnecting a magnetoresistive effect element from a film thickness direction, A circuit diagram of the magnetic sensor of the present embodiment, (A) is a resistance change rate curve when a magnetic field is applied to the element portion of the present invention from the element length direction (sensitivity axis direction) without providing a permanent magnet layer, and (b) is a permanent magnet layer. The resistance change rate curve when a magnetic field is applied to the element portion of the present invention from the element width direction (orthogonal direction), (A) is a mode in which a permanent magnetic layer is provided on the side of the element width direction (orthogonal direction: HA direction) of the element portion of the present invention, and a bias magnetic field is supplied from the element width direction (orthogonal direction). The resistance change rate curve when a magnetic field is applied from the element length direction (sensitivity axis direction), (b) is a permanent magnet layer on the side of the element width direction (orthogonal direction: HA direction) of the element portion of the present invention. And a resistance change rate curve when a magnetic field is applied from the element width direction (orthogonal direction) to the element portion of the present invention with respect to a mode in which a bias magnetic field is supplied from the element width direction (orthogonal direction), Experimental results of measuring the rate of change in resistance when a magnetic field is applied from the direction perpendicular to the sensitivity axis direction and the sensitivity axis for the magnetoresistive effect element of this example, Experimental results of measuring the rate of change in resistance when a magnetic field was applied from the direction perpendicular to the sensitivity axis direction and the sensitivity axis for the magnetoresistive effect element of the conventional example, The partial top view which shows the part of the magnetoresistive effect element especially of the conventional magnetic sensor, (A) is a resistance change rate curve when a magnetic field is applied in the element width direction (sensitivity axis direction) to a conventional element part without forming a permanent magnet layer, and (b) is a permanent magnet. A resistance change rate curve when a magnetic field is applied in the element length direction (perpendicular to the sensitivity axis direction) on a conventional element part without forming a layer, (A) is provided with permanent magnet layers on both sides in the element length direction of the conventional element part, and in the element width direction (with respect to a mode in which a bias magnetic field is applied to the element part in the element length direction (orthogonal direction). (B) shows a resistance change rate curve when a magnetic field is applied in the direction of the sensitivity axis), and (b) is provided with permanent magnet layers on both sides in the element length direction of a conventional element part, and a bias magnetic field is applied to the element part. A resistance change rate curve when a magnetic field is applied in the element length direction (orthogonal direction) with respect to the form applied in the vertical direction (orthogonal direction),

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Magnetic sensor 2, 3 Magnetoresistance effect element 4, 5 Fixed resistance element 6 Bridge circuit 7 Input terminal 8 Ground terminal 9 Differential amplifier 10 External output terminal 11 Integrated circuit 12 Element part 13 Connection electrode part 14 Output extraction part 18 Soft magnetism Body 19 Permanent magnet layer 33 Antiferromagnetic layer 34 Fixed magnetic layer 36 Free magnetic layer L1 Element length L2 (permanent magnet layer) length dimension W1 Element width W2 (permanent magnet layer) width dimension

Claims (8)

A magnetic sensor comprising a magnetoresistive element,
The magnetoresistive element includes an elongated element portion having an element length L1 formed longer than an element width W1, and a permanent magnet layer that supplies a bias magnetic field to the element portion. A pinned magnetic layer whose magnetization direction is fixed, and a free magnetic layer which is laminated on the pinned magnetic layer via a nonmagnetic layer and changes the magnetization direction upon receiving an external magnetic field. The fixed magnetization direction is oriented in the element length direction,
The permanent magnet layer is disposed on a side of the element portion in the element width direction, and a bias magnetic field is supplied to the element portion from the element width direction.   The bias magnetic field is adjusted so that a predetermined magnetic field range from a non-magnetic state to both directions in the element width direction becomes a dead magnetic field range when an external magnetic field acts on the element portion from the element width direction. The magnetic sensor according to 1.   The magnitude of the bias magnetic field is such that the dead magnetic field range is at least a detection magnetic field range defined with respect to a magnetic field from a direction parallel to the sensitivity axis direction with the element length direction as the sensitivity axis direction. The magnetic sensor according to claim 2, wherein is adjusted.   The magnetic sensor according to claim 3, wherein the detection magnetic field range is a range of ± 5 Oe to ± 20 Oe. A plurality of the element parts are arranged at intervals in the element width direction, and the end parts of each element part are connected and formed in a meander shape,
The magnetic sensor according to any one of claims 1 to 4, wherein the permanent magnet layer is disposed outside at least an element portion located on both sides in the element width direction.   The magnetic sensor according to claim 5, wherein the permanent magnet layer is disposed on each side of the element portion in the element width direction.   The magnetic sensor according to claim 5 or 6, wherein a soft magnetic material extending in the width direction of the element portion is arranged in the element length direction of the element portion with a gap from the element portion.   The magnetic sensor according to claim 1, wherein the permanent magnetic layer and the element portion are not in contact with each other.

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