JP5021764B2 - Magnetic sensor - Google Patents

Description

  The present invention relates to a magnetic sensor that can make the temperature coefficient of resistance (TCR) of an element portion closer to zero and improve the operational stability as compared with the prior art.

  A magnetoresistive element using a magnetoresistive effect whose electric resistance value varies with respect to an external magnetic field can be used as a magnetic sensor.

  Conventionally, the resistance value fluctuates when there is a temperature change due to the temperature coefficient of resistance (TCR) of the magnetoresistive element. For this reason, there has been a problem that a stable operation cannot be obtained in a wide temperature range.

  For example, in the invention described in the following Patent Document 1, “the signals according to the equations (5) and (6) are then temperature compensated in a known manner using an appropriate circuit” (Patent Document 1). [Refer to [0023] column).

  In the invention described in Patent Document 2, a giant magnetoresistive element for temperature compensation is formed in a non-flat portion.

  In the invention described in Patent Document 3, a shunt is connected in parallel to the magnetoresistive effect element, and the resistance temperature coefficient of the shunt is different from that of the magnetoresistive effect element.

  However, the inventions described in the above-mentioned patent documents have problems such as increased parasitic resistance, complicated formation of the temperature compensating magnetoresistive effect element, and complicated circuit configuration.

Further, the magnetoresistive effect element changes its resistance by an external magnetic field, and the resistance value Rmin, the maximum resistance value Rmax on the RH curve, or any resistance value between the minimum resistance value Rmin and the maximum resistance value Rmax is changed. Even at times, the temperature coefficient of resistance (TCR) must be adjusted to approach zero, but this point does not take any consideration into the above patent document.
Japanese Patent Laid-Open No. 10-70325 JP 2001-217484 A JP 2005-505750 gazette

  Therefore, the present invention is for solving the above-described conventional problems, and in particular, the temperature coefficient of resistance (TCR) (absolute value) of the element portion including the magnetoresistive effect element with respect to the entire resistance range on the RH curve. An object of the present invention is to provide a magnetic sensor that can be made smaller and easier than before.

The present invention is a magnetic sensor including an element portion using a magnetoresistance effect in which an electric resistance value varies with respect to an external magnetic field,
The element unit includes an antiferromagnetic layer, a pinned magnetic layer whose magnetization direction is fixed, a nonmagnetic conductive layer, and a giant magnetoresistive effect element in which a magnetization direction is fluctuated by an external magnetic field, and a giant magnetic resistance effect element. The temperature coefficient of resistance with respect to the minimum resistance value Rmin on the RH curve and the resistance temperature coefficient with respect to the maximum resistance value Rmax on the RH curve are different from those of the giant magnetoresistive element, and the antiferromagnetic layer, At least one tunnel-type magnetoresistive effect element formed by sequentially laminating the pinned magnetic layer, the insulating barrier layer, and the free magnetic layer;
The giant magnetoresistive effect element and the tunnel type magnetoresistive effect element are connected in series.

  As a result, the temperature coefficient of resistance (TCR) (absolute value) of the element portion can be made smaller and easier than before with respect to the entire resistance range on the RH curve. Further, extra parasitic resistance does not increase.

  Further, the present invention is preferably applied to a configuration in which the fixed magnetization directions of the fixed magnetic layer of the giant magnetoresistive effect element and the tunnel type magnetoresistive effect element constituting the element portion are the same direction.

  In the present invention, the giant magnetoresistive effect element and the tunnel type magnetoresistive effect element are formed on a substrate with a space therebetween, and the giant magnetoresistive effect element and the tunnel type magnetoresistive effect element are nonmagnetic conductive materials. It is preferable that the electrodes are connected in series via an electrode layer.

  In the present invention, it is preferable that the giant magnetoresistive effect element and the tunnel type magnetoresistive effect element are connected in series with each other between upper surfaces or lower surfaces thereof via the electrode layer. The giant magnetoresistive element is a CPP-GMR element in which a current flows in a direction perpendicular to the film surface. With such a configuration, the giant magnetoresistive element and the tunnel type magnetoresistive element can be appropriately and easily connected in series.

  In the present invention, the giant magnetoresistive effect element, the tunnel type magnetoresistive effect element, and the giant magnetoresistive effect element, It is preferable that a tunnel type magnetoresistive effect element is disposed. Both the giant magnetoresistive effect element and the tunnel type magnetoresistive effect element can be efficiently arranged within a predetermined installation area.

  In the present invention, the cross-sectional area of the giant magnetoresistive element from the plane direction parallel to the substrate surface is smaller than the cross-sectional area of the tunnel-type magnetoresistive element from the plane direction parallel to the substrate surface. preferable. Thereby, it is easy to match so that the resistance values of the giant magnetoresistive effect element and the tunnel type magnetoresistive effect element coincide. In particular, in the present invention, it is easy to adjust the cross-sectional area of each element by arranging the giant magnetoresistive element and the tunnel type magnetoresistive element at a distance on the substrate.

  In the present invention, the giant magnetoresistive effect element and the tunnel type magnetoresistive effect element from the plane direction parallel to the substrate surface preferably have a substantially circular cross section. It is possible to reduce the shape anisotropy, appropriately change resistance with respect to an external magnetic field from any direction, and improve detection accuracy.

  According to the magnetic sensor of the present invention, the temperature coefficient of resistance (TCR) (absolute value) of the element portion can be made smaller and easier than before with respect to the entire resistance range on the RH curve. Further, extra parasitic resistance does not increase.

  FIG. 1A is a partial plan view of one element part constituting the magnetic sensor in the present embodiment, and FIG. 1B is a cross-sectional view taken along the alternate long and short dash line shown in FIG. FIG. 2 is a partial cross-sectional view showing a cut surface of a tunnel-type magnetoresistive effect element (TMR element) constituting the element portion, and FIG. 3 shows the cut portion. FIG. 4 is a partial cross-sectional view showing the cut surface of the giant magnetoresistive effect element (GMR element) that constitutes the structure, FIG. 4 is a circuit configuration diagram of the magnetic sensor in this embodiment, and FIG. FIG. 6 is a partial cross-sectional view showing a cut surface of one element part constituting a magnetic sensor in another embodiment according to the present invention, and FIG. 6 is a tunnel type magnetoresistive effect element constituting the element part of FIG. Layer thickness element with a giant magnetoresistive effect element laminated Partial cross-sectional view showing a cut the cut surface from 7, R-H curves of the tunneling magnetoresistive element and a giant magnetoresistive effect element, a.

  As shown in FIG. 4, in the magnetic sensor S of the present embodiment, the four element portions 1 to 4 constitute a bridge circuit.

  As shown in FIG. 4, the first element part 1 and the second element part 2 are connected in series via an output extraction part 6. The third element portion 3 and the fourth element portion 4 are connected in series via the output extraction portion 7. As shown in FIG. 4, the output extraction units 6 and 7 are connected to the differential amplifier 8. As shown in FIG. 4, the second element unit 2 and the third element unit 3 are connected via an input terminal 9, and the first element unit 1 and the fourth element unit 4 are connected via a ground terminal 10. Yes. An external output terminal 11 is connected to the output side of the differential amplifier 8.

  In the first element portion 1 in this embodiment, a plurality of tunnel type magnetoresistive elements (hereinafter referred to as TMR elements) and giant magnetoresistive elements (hereinafter referred to as CPP-GMR elements) are connected in series. It is a configuration. The second element unit 2, the third element unit 3, and the fourth element unit 4 have the same configuration as the first element unit 1.

  In the following, the configuration of the first element unit 1 will be described, but the same applies to the second element unit 2, the third element unit 3, and the fourth element unit 4.

  As shown in FIG. 1, in the first element unit 1, a plurality of TMR elements 21 and CPP-GMR elements 22 are arranged on a substrate 20 at intervals.

  In the configuration of FIG. 1A, three TMR elements 21 and CPP-GMR elements 22 are arranged in the X direction in the figure, and one TMR element 21 and CPP-GMR elements 22 are arranged in the Y direction in the figure. In total, six TMR elements 21 and CPP-GMR elements 22 are provided.

  As shown in FIGS. 1A and 1B, a lower electrode layer 23 extending in the Y direction in the figure is formed on the substrate 20 at a predetermined interval in the X direction in the figure.

  One TMR element 21 and one CPP-GMR element 22 are formed on each lower electrode layer 23 with an interval in the Y direction in the figure.

  As shown in FIG. 1A, a CPP-GMR element 22 is formed on the upper side of the drawing and a TMR element 21 is formed on the lower side of the drawing on the lower electrode layer 23 on the leftmost side of the drawing. On the lower electrode layer 23 in the middle of the figure, a TMR element 21 is formed on the upper side in the figure, and a CPP-GMR element 22 is formed on the lower side in the figure. A CPP-GMR element 22 is formed on the upper side in the drawing, and a TMR element 21 is formed on the lower side in the drawing on the lower electrode layer 23 on the rightmost side in the drawing.

  As shown in FIGS. 1A and 1B, the upper surface of the TMR element 21 on the adjacent lower electrode layer 23 and the upper surface of the CPP-GMR element 22 are connected by the upper electrode layer 24, and the TMR element 21 and the CPP-GMR element 22 are alternately connected in series via the lower electrode layer 23 and the upper electrode layer 24 (see also FIG. 4).

  Although not shown in FIG. 1B, the periphery of the lower electrode layer 23, the periphery of the CPP-GMR element 22 and the TMR element 21, and the periphery of the upper electrode layer 24 are filled with an insulating layer.

  A CPP (Current perpendicular to the plane) -CPP-GMR element 22 is provided with electrode layers 23 and 24 above and below, and a current flows in the film thickness direction (Z direction) through the CPP-GMR element 22. On the other hand, the type in which current flows in the direction parallel to the film surface in the GMR element is called a CIP (Current In the Plane) -GMR element. On the other hand, the TMR element 21 is an element that does not function unless the electrode layers 23 and 24 are necessarily provided above and below it so that current flows in the film thickness direction in the TMR element 21.

  As shown in FIG. 2, the TMR element 21 is laminated in the order of, for example, a base layer 30, an antiferromagnetic layer 31, a pinned magnetic layer 32, an insulating barrier layer 33, a free magnetic layer 34, and a protective layer 35 from the bottom. For example, the underlayer 30 is Ta, the antiferromagnetic layer 31 is IrMn, the pinned magnetic layer 32 is CoFeB, the insulating barrier layer 33 is MgO, the free magnetic layer 34 is CoFeB, and the protective layer 35 is Ta. The laminated structure is not limited to the configuration of FIG. For example, the pinned magnetic layer 32 can have a laminated ferrimagnetic structure of a first magnetic layer / nonmagnetic intermediate layer / second magnetic layer.

  As shown in FIG. 3, the CPP-GMR element 22 includes, for example, an underlayer 40, a lower antiferromagnetic layer 41, a lower fixed magnetic layer 42, a lower nonmagnetic conductive layer 43, a free magnetic layer 44, The upper nonmagnetic conductive layer 45, the upper pinned magnetic layer 46, the upper antiferromagnetic layer 47, and the protective layer 48 are laminated in this order. For example, the underlayer 30 is Ta, the antiferromagnetic layers 41 and 47 are IrMn, the pinned magnetic layers 42 and 46 are FeCo, the nonmagnetic conductive layers 43 and 45 are Cu, the free magnetic layer 44 is CoMnGe, and the protective layer 48 is Ta. The laminated structure is not limited to the configuration of FIG. For example, the pinned magnetic layers 42 and 46 can have a laminated ferrimagnetic structure of a first magnetic layer / nonmagnetic intermediate layer / second magnetic layer. 3 is a dual type GMR element in which a nonmagnetic conductive layer, a pinned magnetic layer, and an antiferromagnetic layer are stacked one above the other with a free magnetic layer 44 as a center. Of course, a single-type GMR element in which a fixed magnetic layer, a nonmagnetic conductive layer, and a free magnetic layer are formed one by one may be used.

  As shown in FIG. 3, one reason why the CPP-GMR element 22 is dual type is that the element resistance of the CPP-GMR element 22 is set so that the element resistance of the CPP-GMR element 22 approaches the element resistance of the TMR element 21. This is to make it larger.

  Further, as shown in FIG. 1, the cross-sectional area of the CPP-GMR element 22 from the plane direction parallel to the substrate surface (plane parallel to the film surface of the CPP-GMR element 22 (XY plane)) is It is smaller than the cross-sectional area of the TMR element 21 from the parallel plane direction. Thereby, the element resistance of the CPP-GMR element 22 can be increased, and the element resistance of the CPP-GMR element 22 can be made closer to the element resistance of the large TMR element 21 by providing the insulating barrier layer 33.

  Further, as shown in FIG. 1A, the cross-sectional shapes of the CPP-GMR element 22 and the TMR element 21 from a plane (XY plane) direction parallel to the substrate surface are both substantially circular. For this reason, the free magnetic layers 34 and 44 constituting the CPP-GMR element 22 and the TMR element 21 react with high sensitivity to improve detection accuracy regardless of the direction from which the external magnetic field extends. I can do it.

  The fixed magnetization directions (P direction) of the fixed magnetic layers 32, 42, and 46 constituting the CPP-GMR element 22 and the TMR element 21 are the same direction. In FIG. 1A, the fixed magnetization direction (P direction) of the fixed magnetic layers 32, 42, and 46 is set in the Y direction shown in the figure, for example.

  Therefore, the RH curves of the CPP-GMR element 22 and the TMR element 21 are both as shown in FIG. The horizontal axis in the RH curve in FIG. 7 indicates the magnetic field strength of the external magnetic field H. A positive value and a negative value mean that the external magnetic field is antiparallel. The resistance value R on the vertical axis may be a resistance change rate (R / R). As shown in FIG. 7, the electric resistance values of the CPP-GMR element 22 and the TMR element 21 fluctuate due to the intensity change of the external magnetic field H, and the maximum resistance value Rmax or the minimum resistance value when the magnetic field intensity of a certain external magnetic field H is obtained. Rmin.

  Each of the TMR element 21 and the CPP-GMR element 22 has a specific temperature coefficient of resistance (TCR). However, both the TMR element 21 and the CPP-GMR element 22 have different resistance temperature coefficients (TCR) when the resistance values on the RH curve are different.

  In the present embodiment, the temperature coefficient of resistance (TCR) with respect to the minimum resistance value Rmin (see FIG. 7) and the resistance temperature coefficient (TCR) with respect to the maximum resistance value Rmax (see FIG. 7) on the RH curve of the CPP-GMR element 22. ) Are positive values. On the other hand, the resistance temperature coefficient (TCR) for the minimum resistance value Rmin of the TMR element 21 and the resistance temperature coefficient (TCR) for the maximum resistance value Rmax are both negative values.

Here, the temperature coefficient of resistance (TCR) with respect to the minimum resistance value Rmin is defined as (Rmin (85 ° C.) − Rmin (25 ° C.)) / Rmin (25 ° C.) / (85-25) × 10 ⁶ (ppm / ° C.). Is done. On the other hand, the temperature coefficient of resistance (TCR) with respect to the maximum resistance value Rmax is defined as (Rmax (85 ° C.) − Rmax (25 ° C.)) / Rmax (25 ° C.) / (85-25) × 10 ⁶ (ppm / ° C.). Is done.

  The resistance temperature coefficient (TCR) with respect to the minimum resistance value Rmin on the RH curve of the CPP-GMR element 22 is in the range of about 100 to 2000 ppm / ° C., and the minimum resistance of the TMR element 21 on the RH curve is The temperature coefficient of resistance (TCR) with respect to the value Rmin is in the range of about -100 to -1000 ppm / ° C. The resistance temperature coefficient (TCR) with respect to the maximum resistance value Rmax on the RH curve of the CPP-GMR element 22 is in the range of about 100 to 2000 ppm / ° C., and the TMR element 21 has an RH curve on the RH curve. The temperature coefficient of resistance (TCR) with respect to the maximum resistance value Rmax is in the range of about −500 to −2000 ppm / ° C.

  In the present embodiment, the first element unit 1 has a configuration in which a CPP-GMR element 22 and a TMR element 21 are connected in series, a resistance temperature coefficient (TCR) with respect to a minimum resistance value Rmin on the RH curve, and Since the resistance temperature coefficient (TCR) with respect to the maximum resistance value Rmax has a different sign between the CPP-GMR element 22 and the TMR element 21, the resistance temperature coefficient (TCR) with respect to the minimum resistance value Rmin as the first element unit 1 And the temperature coefficient of resistance (TCR) with respect to the maximum resistance value Rmax can be brought close to zero, respectively. The resistance temperature coefficient for the resistance value between the minimum resistance value Rmin and the maximum resistance value Rmax takes a value between the resistance temperature coefficient for the minimum resistance value Rmin and the resistance temperature coefficient for the maximum resistance value Rmax. Therefore, as in the present embodiment, the resistance temperature coefficient (TCR) (absolute value) with respect to the minimum resistance value Rmin on the RH curve of the first element unit 1 and the resistance temperature coefficient (TCR) with respect to the maximum resistance value Rmax. ) (Absolute value) is adjusted so that both become smaller, the resistance temperature coefficient (TCR) (absolute value) of the first element unit 1 is made to be larger than the conventional resistance range on the RH curve. It can be easily and appropriately reduced.

  For example, as shown in an experiment to be described later, in the configuration in which the first element unit 1 includes the TMR element 22 and the Ta layer connected in series, the resistance temperature coefficient (TCR) of the Ta layer is a positive value, and the resistance of the TMR element 22 is The temperature coefficient (TCR) is an opposite sign.

  However, since the Ta layer does not have the characteristic of drawing the RH curve as shown in FIG. 7 (the resistance does not change with respect to the external magnetic field), for example, the resistance temperature coefficient (TCR) of the Ta layer is the first Even if the temperature coefficient of resistance (TCR) (absolute value) with respect to the minimum resistance value Rmin on the RH curve of the element unit 1 is adjusted to be small, the maximum on the RH curve of the first element unit 1 The resistance temperature coefficient (TCR) (absolute value) with respect to the resistance value Rmax remains large, and the resistance temperature coefficient (TCR) (absolute value) of the first element unit 1 is compared with the entire resistance range on the RH curve. And cannot be made appropriately small.

  On the other hand, as in this embodiment, the CPP-GMR element 22 and the TMR element 21 are connected in series to form the first element unit 1, whereby the temperature coefficient of resistance (TCR) (TCR) of the first element unit 1 ( (Absolute value) can be reduced with respect to the entire resistance range on the RH curve.

  The temperature coefficient of resistance of the first element unit 1 can be adjusted by the resistance values and the number of elements of the TMR element 21 and the CPP-GMR element 22. For example, as for the number of elements, the TMR elements 21 and the CPP-GMR elements 22 do not have to be the same number as shown in FIG. If the temperature coefficient of resistance of the first element unit 1 falls within the above range, the number of elements is irrelevant as long as there is at least one CPP-GMR element 22 and one TMR element 21. Also, the way of connecting the elements is arbitrary. In FIG. 1A, the CPP-GMR elements 22 and the TMR elements 21 are alternately connected in series, but there is no need to connect them alternately. For example, the connection may be made as CPP-GMR element 22 -CPP-GMR element 22 -TMR element 21 -TMR element 21.

  Note that the resistance temperature coefficient (TCR) (absolute value) of the CPP-GMR element 22 and the TMR element 21 resistance temperature coefficient (TCR) (absolute value) are close to each other so that the resistance temperature coefficient of the element portion is reduced. Easy to adjust.

  Further, in the present embodiment, there are only portions of the lower electrode layer 23 and the upper electrode layer 24 that should become parasitic resistance, and the lower electrode layer 23 and the upper electrode layer 24 are formed of a good conductor such as Al or Au. Since the parasitic resistance can be made very small, the temperature coefficient of resistance of the first element unit 1 is hardly affected.

Here, dimensions and the like will be described. The cross-sectional area on the plane (XY plane) parallel to the film surface of the TMR element 21 is in the range of 10 to 100 μm ² (see FIG. 1A). The cross-sectional area on the plane (XY plane) parallel to the film plane of the CPP-GMR element 22 is in the range of 1 to 10 μm ² (see FIG. 1A). The film thickness of the TMR element 21 is in the range of 500 to 1000 mm (see FIG. 1B). The film thickness of the CPP-GMR element 22 is in the range of 500 to 1000 mm (see FIG. 1B). A distance T1 between elements adjacent in the X direction and a distance T2 between elements adjacent in the Y direction are 5 to 100 μm. The minimum resistance value Rmin (at 25 ° C.) on the RH curve of the CPP-GMR element 22 and the TMR element 21 is in the range of 10 to 10 kΩ, and the R− of the CPP-GMR element 22 and the TMR element 21 is R−. The maximum resistance value Rmax (at 25 ° C.) on the H curve is in the range of 12 to 30 kΩ.

  The 2nd element part 2, the 3rd element part 3, and the 4th element part 4 are also the same as the structure of the 1st element part 1 demonstrated in FIGS. 1-3. Here, the fixed magnetization direction (P direction) of the fixed magnetic layer of the TMR element 21 and the CPP-GMR element 22 constituting the third element unit 3 is the same as that of the first element unit 1, but the second element unit 2 and The fixed magnetization direction (P direction) of the fixed magnetic layer of the TMR element 21 and the CPP-GMR element 22 constituting the fourth element unit 4 is opposite to the first element unit 1 (see FIG. 4).

  Accordingly, in the bridge circuit shown in FIG. 4, when the electrical resistance values of the first element unit 1 and the third element unit 3 increase, the electrical resistance values of the second element unit 2 and the fourth element unit 4 decrease. When the electric resistance values of the first element part 1 and the third element part 3 are lowered, the electric resistance values of the second element part 2 and the fourth element part 4 are in an increasing relationship. Therefore, a large differential output can be obtained by the differential amplifier 8. A circuit configuration including the first element unit 1 and the second element unit 2 connected in series via the output extraction unit 6 may be used instead of the bridge circuit, but the output is obtained by configuring the bridge circuit to obtain a differential output. The value can be increased, and the detection accuracy can be improved.

  In the embodiment shown in FIG. 1, a CPP-GMR element 22 and a TMR element 21 are formed on a substrate 20 with an interval therebetween. The CPP-GMR element 22 and the TMR element 21 can be formed using different substrates, but can also be formed on a common substrate 20. However, since the laminated structure is different between the CPP-GMR element 22 and the TMR element 21, for example, after the CPP-GMR element 22 is first formed, the TPP element 21 is masked with a resist or the like. Then, the mask is removed. In addition, since the fixed magnetization direction (P direction) of the fixed magnetic layer of the CPP-GMR element 22 and the TMR element 21 constituting the first element part 1 and the third element part 3 shown in FIGS. 1 and 4 is the same direction. After the CPP-GMR element 22 and the TMR element 21 constituting the first element part 1 and the third element part 3 are formed, fixed magnetization of the fixed magnetic layer can be performed by the same annealing process in a magnetic field. After the second element part 2 and the fourth element part 4 are formed on different substrates in a different process from the first element part 1 and the third element part 3, the first element part 1 and the third element part 3 are formed. And a substrate provided with the second element part 2 and the fourth element part 4 are joined to form a bridge circuit shown in FIG. Alternatively, the first element portion 1 to the fourth element portion 4 are formed on a common substrate, and are divided into the first element portion 1 and the third element portion 3, and the second element portion 2 and the fourth element portion 4. Then, the substrate including the second element unit 2 and the fourth element unit 4 is inverted 180 degrees, the substrate including the first element unit 1 and the third element unit 3, and the second element unit The bridge circuit shown in FIG. 4 may be formed by bonding the substrate having 2 and the fourth element portion 4 together.

  In the embodiment in which the CPP-GMR element 22 and the TMR element 21 are formed on the substrate 20 with a space therebetween, the CPP-GMR element 22 and the TMR element 21 can be formed separately, so that as shown in FIG. The CPP-GMR element 22 and the TMR element 21 can be easily formed so that the cross-sectional area of the TMR element 21 from the parallel plane direction (XY plane) is larger than the cross-sectional area of the CPP-GMR element 22.

  Further, as shown in FIG. 1A, the planar shape of the first element portion 1 including the TMR element 21, the CPP-GMR element 22, the lower electrode layer 23, and the upper electrode layer 24 is a folded shape. ing. In FIG. 1A, the first element portion 1 is folded back a plurality of times, and the planar shape of the first element portion 1 is a zigzag folded shape. As described above, by arranging the TMR element 21 and the CPP-GMR element 22 so that the planar shape of the first element unit 1 is a folded shape, a plurality of TMR elements 21 and The CPP-GMR element 22 can be arranged.

  Further, a CIP-GMR element may be used instead of the CPP-GMR element 22. However, since the CPP-GMR element 22 has the same electrode arrangement as the TMR element 21, the CPP-GMR element 22 can be easily and appropriately used. And the TMR element 21 can be connected in series via the electrode layers 23 and 24.

  In the present embodiment, the CPP-GMR element 22 and the TMR element 21 may be laminated as shown in FIG. In FIG. 5, a laminated element 50 in which the CPP-GMR element 22 is laminated on the TMR element 21 is formed. The laminated element 50 may have a structure in which the TMR element 21 is laminated on the CPP-GMR element 22. As shown in FIG. 5, a plurality of the laminated elements 50 are provided, and the laminated elements 50 are connected in series via the lower electrode layer 23 or the upper electrode layer 24. 5 also has the circuit configuration of the first element unit 1 shown in FIG.

  In the laminated element 50 shown in FIG. 5, the free magnetic layer constituting the TMR element 21 and the free magnetic layer constituting the CPP-GMR element 22 are provided as a common layer (a layer denoted by reference numeral 58 in FIG. 5). ).

  Each laminated element 50 has a layer structure shown in FIG. The laminated element 50 includes, from below, an underlayer 51, a seed layer 52, an antiferromagnetic layer 53, a pinned magnetic layer 65, an insulating barrier layer 57, a free magnetic layer 58, a nonmagnetic conductive layer 59, a pinned magnetic layer 66, and an antiferroelectric layer. The magnetic layer 63 and the protective layer 64 are stacked in this order. The seed layer 52 is a layer for adjusting the crystal orientation of the antiferromagnetic layer 53. The fixed magnetization directions of the fixed magnetic layers 65 and 66 are the same. The cross section of the multilayer element 50 on the plane parallel to the film surface (XY plane) is preferably substantially circular as in the TMR element 21 and the CPP-GMR element 22 shown in FIG. is there. For the material of each layer, refer to the descriptions in FIGS.

  As shown in FIG. 6, each of the pinned magnetic layers 65 and 66 has a laminated ferrimagnetic structure of first magnetic layers 54 and 62, nonmagnetic intermediate layers 55 and 61, and second magnetic layers 56 and 60.

  As shown in FIG. 6, with the free magnetic layer 58 as a common layer, an antiferromagnetic layer 53, a fixed magnetic layer 65, and an insulating barrier layer 57 constituting the TMR element 21 are stacked below the free magnetic layer 58. ing. A nonmagnetic conductive layer 59, a fixed magnetic layer 66, and an antiferromagnetic layer 63 constituting the CPP-GMR element 22 are laminated on the free magnetic layer 58.

  When the CPP-GMR element 22 is arranged on the upper side of the TMR element 21, the cross-sectional area from the plane direction parallel to the film surface (XY plane) of the CPP-GMR element 22 is calculated as the film surface (XY) of the TMR element 21. It is easy to form smaller than the cross-sectional area from the surface direction parallel to the surface. The side surface of the multilayer element 50 shown in FIG. 6 is parallel to the Z direction shown in the form of FIG. 6, but in fact, it is inclined so that the width dimension (dimension in the X direction) of the multilayer element 50 increases toward the bottom. ing.

  However, in the embodiment of FIG. 1, the cross-sectional area from the plane direction parallel to the film plane (XY plane) of the CPP-GMR element 22 is the plane parallel to the film plane (XY plane) of the TMR element 21. It is difficult to form smaller than the cross-sectional area from the direction. Therefore, in the embodiment of FIG. 6, for example, the current limiting layer 67 is provided in the nonmagnetic conductive layer 59. The current limiting layer 67 is preferably an insulator in which a plurality of through holes are formed. The current limiting layer 67 is an oxide such as Al, Mg, or Cu, a nitride, or the like. The current path is reduced by the current limiting layer 67, so that the cross-sectional area of the CPP-GMR element 22 can be apparently reduced.

  The laminated element in which the CPP-GMR element 22 and the TMR element 21 are laminated may have, for example, a structure in which the CPP-GMR element 22 having the laminated structure shown in FIG. 3 is laminated on the TMR element 21 having the laminated structure shown in FIG. In this case, each of the TMR element 21 and the CPP-GMR element 22 is provided with a free magnetic layer.

  The application of the magnetic sensor S of the present embodiment is not particularly limited. Any application that detects an external magnetic field can be used as a magnetic switch or a potentiometer.

The TMR element 21 and the CPP-GMR element 22 were formed with the following layer configuration.
(Layer structure of TMR element 21)
From below, underlayer 30; Ta (200) / seed layer; Ru (40) / antiferromagnetic layer 31; Ir _{20 at%} Mn _{80 at%} (80) / pinned magnetic layer 32 [first magnetic layer; Co _{70 at%} Fe _{30 at%} (22) / nonmagnetic intermediate layer; Ru (9.1) / second magnetic layer; [{Co ₅₀ Fe ₅₀ } _{70 at%} B _{30 at%} (18) / Co _{50 at%} Fe _{50 at%} (8)]] / Insulation barrier layer 33; Mg _{50 at%} O _{50 at%} / Free magnetic layer 34 [Co _{50 at%} Fe _{50 at%} (10) / {Co ₅₀ Fe ₅₀ } _{70 at%} B _{30 at%} (15)] / Protective layer 35; [Ru (20) / Ta (360)]. The numerical values in parentheses for each layer indicate the film thickness and the unit is Å. The total film thickness of the TMR element 21 was 800 mm.

The cross-sectional area (element area) from the plane direction parallel to the film surface is 10 μm ² (3.57 μmφ), and the minimum resistance value Rmin (at 25 ° C.) on the RH curve is 10Ω. did.

(Layer structure of CPP-GMR element 22)
From bottom, underlayer 30; Ta (30) / seed layer; {Ni ₈₀ Fe ₂₀ } _{64 at%} Cr _{36 at%} (50) / lower antiferromagnetic layer 41; Ir _{20 at%} Mn _{80 at%} (70) / lower side _Pinned magnetic layer 42 [first magnetic layer; Co _{70 at%} Fe _{30 at%} (30) / nonmagnetic intermediate layer; Ru (9.1) / second magnetic layer; [Co _{60 at%} Fe _{40 at%} (10) / Co _{50 at %} Mn _{25 at%} Ge _{25 at%} (40)]] / lower nonmagnetic conductive layer 43; Cu (50) / free magnetic layer 44; Co _50at% Mn _25at% Ge _25at% (80) / upper nonmagnetic conductive layer 45 ; Cu (50) / the upper fixed magnetic layer 46 [[second magnetic _{layer; Co 50at% Mn 25at% Ge} 25at% (40) / Co 60at% Fe 40at% (10) / nonmagnetic intermediate ; Ru (9.1) / the first magnetic _{layer; Co 60at% Fe 40at% (} 30)] / upper antiferromagnetic layer _{47; Ir 20at% Mn 80at%} (70) / protective layer 48; Ta of (222) Laminated in order. The numerical values in parentheses for each layer indicate the film thickness and the unit is Å. The total film thickness of the CPP-GMR element 22 was 800 mm.

The cross-sectional area (element area) from the plane direction parallel to the film surface is 0.01 μm ² (0.113 μmφ), and the minimum resistance value Rmin (at 25 ° C.) on the RH curve is 10Ω. Designed.

In addition to the TMR element 21 and the CPP-GMR element 22, a Ta layer was formed with a thickness of 800 mm. The Ta layer was designed to have a cross-sectional area (element area) from a plane direction parallel to the film surface of 0.015 μm ² (0.14 μmφ) and an element resistance (at 25 ° C.) of 10Ω. Similarly to the TMR element 21 and the CPP-GMR element 22, a current was passed through the Ta layer from the film thickness direction.

  FIG. 8 is a graph showing the relationship between the temperature in the TMR element 21 and the normalized resistance. The resistance value at 25 ° C. was normalized as 1. The normalized resistance was measured for both the minimum resistance value Rmin and the maximum resistance value Rmax on the RH curve shown in FIG. From the experimental results of the temperature and normalized resistance shown in FIG. 8, the resistance temperature coefficient (TCR) (described as TCRmin in FIG. 8) with respect to the minimum resistance value Rmin of the TMR element 21 was −148.3 ppm / ° C. . Further, the temperature coefficient of resistance (TCR) (denoted as TCRmax in FIG. 8) with respect to the maximum resistance value Rmax of the TMR element 21 was −484.1 ppm / ° C.

  FIG. 9 is a graph showing the relationship between the temperature in the CPP-GMR element 22 and the normalized resistance. The resistance value at 25 ° C. was normalized as 1. The normalized resistance was measured for both the minimum resistance value Rmin and the maximum resistance value Rmax on the RH curve shown in FIG. From the experimental results of the temperature and normalized resistance shown in FIG. 9, the resistance temperature coefficient (TCR) (denoted as TCRmin in FIG. 9) with respect to the minimum resistance value Rmin of the CPP-GMR element 22 was 280.9 ppm / ° C. It was. Further, the temperature coefficient of resistance (TCR) (described as TCRmax in FIG. 9) with respect to the maximum resistance value Rmax of the CPP-GMR element 22 was 226.3 ppm / ° C.

  FIG. 10 is a graph showing the relationship between the temperature in the Ta layer and the normalized resistance. The resistance value at 25 ° C. was normalized as 1. From the experimental results of the temperature and normalized resistance shown in FIG. 10, the resistance temperature coefficient (TCR) of the Ta layer was 3472.7 ppm / ° C.

  In the experiment, two TMR elements 21 and two CPP-GMR elements 22 were connected in series. Cu was used for the electrode layer connecting the TMR element 21 and the CPP-GMR element 22. Incidentally, the temperature coefficient of resistance of the electrode layer was almost zero ppm / ° C.

  FIG. 11 is a graph showing the relationship between the temperature and the standard resistance for the element portion (example) in which the TMR element 21 and the CPP-GMR element 22 are connected in series. The resistance value at 25 ° C. was normalized as 1. As shown in FIG. 11, changes in the minimum resistance value Rmin and the maximum resistance value Rmax normalized by the temperature change can be reduced. As shown in FIG. 11, the temperature coefficient of resistance (TCR) (described as TCRmin in FIG. 11) with respect to the minimum resistance value Rmin of the element portion is 38.2 ppm / ° C., and the resistance temperature coefficient with respect to the maximum resistance value Rmax of the element portion. (TCR) (described as TCRmax in FIG. 11) was −109.1 ppm / ° C.

  FIG. 12 is a graph showing the relationship between the temperature and the standard resistance for an element part (comparative example) in which two TMR elements 21 and two Ta layers are connected in series. Here, the absolute value of the resistance temperature coefficient (TCR) of the Ta layer is an order of magnitude larger than the resistance temperature coefficient (TCRmin) with respect to the minimum resistance value Rmin of the TMR element 21, and therefore the film thickness of the Ta layer and the plane direction parallel to the film surface The resistance value of the Ta layer was designed to be smaller than the resistance of the TMR 21 by adjusting the cross-sectional area (element area) from. The resistance value at 25 ° C. was normalized as 1. Cu was used for the electrode layer connecting the TMR element 21 and the Ta layer. As shown in FIG. 12, the standardized change in the minimum resistance value Rmin is adjusted to be small with respect to the temperature change. At this time, the standardized change in the maximum resistance value Rmax is with respect to the temperature change. Remained big. As shown in FIG. 12, the resistance temperature coefficient (TCR) (described as TCRmin in FIG. 12) with respect to the minimum resistance value Rmin of the element portion is −49.2 ppm / ° C., and the resistance temperature with respect to the maximum resistance value Rmax of the element portion. The coefficient (TCR) (described as TCRmax in FIG. 12) was −333.7 ppm / ° C.

  Even if the Ta layer is connected in series with the TMR element 21 in this way, the resistance temperature coefficient (TCR) can be improved with respect to one resistance value of the minimum resistance value Rmin or the maximum resistance value Rmax. The temperature coefficient of resistance (TCR) (absolute value) for the still remained large.

  On the other hand, in this embodiment in which the TMR element 21 and the CPP-GMR element 22 are connected in series, the resistance temperature coefficient (TCR) (absolute value) with respect to the minimum resistance value Rmin and the resistance temperature coefficient (TCR) with respect to the maximum resistance value Rmax (absolute Both values can be appropriately reduced. The resistance temperature coefficient for the resistance value between the minimum resistance value Rmin and the maximum resistance value Rmax is a value between the resistance temperature coefficient for the minimum resistance value Rmin and the resistance temperature coefficient for the maximum resistance value Rmax. Therefore, as in this embodiment, both the resistance temperature coefficient (TCR) (absolute value) with respect to the minimum resistance value Rmin and the resistance temperature coefficient (TCR) (absolute value) with respect to the maximum resistance value Rmax are appropriately reduced. Thus, the temperature coefficient of resistance (TCR) (absolute value) for the entire resistance range on the RH curve of the element portion can be appropriately reduced as compared with the conventional case.

(A) is the fragmentary top view of one element part which comprises the magnetic sensor in this embodiment, (b) is the part which cut | disconnects the dashed-dotted line shown to Fig.1 (a) from a film thickness direction, and shows the cut surface Sectional view, A partial cross-sectional view showing a cut surface of a tunnel-type magnetoresistive effect element (TMR element) constituting the element section cut from the film thickness direction, A partial cross-sectional view showing a cut surface of a giant magnetoresistive effect element (GMR element) constituting the element portion cut from the film thickness direction, The circuit block diagram of the magnetic sensor in this embodiment, 1 is a partial cross-sectional view showing a cut surface of one element part constituting the magnetic sensor in the present embodiment different from that shown in FIG. FIG. 6 is a partial cross-sectional view showing a cut surface of a laminated element in which a tunnel type magnetoresistive effect element and a giant magnetoresistive effect element constituting the element part of FIG. RH curve diagram of tunnel type magnetoresistive effect element and giant magnetoresistive effect element, A graph showing the relationship between temperature and normalized resistance in the TMR element; A graph showing the relationship between temperature and normalized resistance in a CPP-GMR element; A graph showing the relationship between the temperature in the Ta layer and the normalized resistance; 8 is a graph showing the relationship between the temperature and the normalized resistance in the element portion in which the TMR element in FIG. 8 and the CPP-GMR element in FIG. 9 are connected in series; 8 is a graph showing the relationship between the temperature and the normalized resistance in the element portion in which the TMR element in FIG. 8 and the Ta layer in FIG. 10 are connected in series;

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 1st element part 2 2nd element part 3 3rd element part 4 4th element part 20 Substrate 21 TMR element 22 CPP-GMR element 23 Lower electrode layer 24 Upper electrode layer 31, 41, 47, 53, 63 Magnetic layer 32, 42, 46, 65, 66 Fixed magnetic layer 33, 57 Insulating barrier layer 34, 44, 58 Free magnetic layer 35, 48, 64 Protective layer 43, 45, 59 Nonmagnetic conductive layer 50 Multilayer element 67 Current limit layer

Claims (7)

A magnetic sensor including an element portion using a magnetoresistance effect in which an electric resistance value varies with respect to an external magnetic field,
The element unit includes an antiferromagnetic layer, a pinned magnetic layer whose magnetization direction is fixed, a nonmagnetic conductive layer, and a giant magnetoresistive effect element in which a magnetization direction is fluctuated by an external magnetic field, and a giant magnetic resistance effect element. The temperature coefficient of resistance with respect to the minimum resistance value Rmin on the RH curve and the resistance temperature coefficient with respect to the maximum resistance value Rmax on the RH curve are different from those of the giant magnetoresistive element, and the antiferromagnetic layer, At least one tunnel-type magnetoresistive effect element formed by sequentially laminating the pinned magnetic layer, the insulating barrier layer, and the free magnetic layer;
The giant magnetoresistive effect element and the tunnel type magnetoresistive effect element are connected in series.   2. The magnetic sensor according to claim 1, wherein fixed magnetization directions of the fixed magnetic layer of the giant magnetoresistive effect element and the tunnel type magnetoresistive effect element constituting the element portion are the same direction.   The giant magnetoresistive effect element and the tunnel type magnetoresistive effect element are formed on a substrate at an interval, and the giant magnetoresistive effect element and the tunnel type magnetoresistive effect element comprise an electrode layer made of a nonmagnetic conductive material. The magnetic sensor according to claim 1, wherein the magnetic sensors are connected in series via each other.   4. The magnetic sensor according to claim 3, wherein the giant magnetoresistive effect element and the tunnel type magnetoresistive effect element are connected in series with each other between upper surfaces or lower surfaces thereof via the electrode layer.   The giant magnetoresistive effect element and the tunnel magnetoresistive effect element, the tunnel magnetoresistive effect element, and the tunnel magnetoresistive effect element and the tunnel magnetoresistive effect element so that a planar shape of the element portion including the electrode layer is a folded shape. The magnetic sensor according to claim 3 or 4, wherein an element is disposed.   6. The cross-sectional area of the giant magnetoresistive element from a plane direction parallel to the substrate surface is smaller than the cross-sectional area of the tunnel-type magnetoresistive element from a plane direction parallel to the substrate surface. A magnetic sensor according to claim 1.   The magnetic sensor according to claim 1, wherein cross-sectional shapes of the giant magnetoresistive effect element and the tunnel type magnetoresistive effect element from a plane direction parallel to the substrate surface are substantially circular.

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