JP2015175620A - magnetic sensor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a magnetic sensor having improved detection accuracy.SOLUTION: A magnetic sensor includes a first bridge circuit BC1 and a second bridge circuit BC2 provided with self-pinned magneto-resistance effect elements. The first bridge circuit BC1 comprises a first magneto-resistance effect element M1 pinned in a first direction D1, a second magneto-resistance effect element M2 pinned in the first direction, a third magneto-resistance effect element M3 pinned in a second direction D2, and a fourth magneto-resistance effect element M4 pinned in the second direction D2. The second bridge circuit BC2 comprises a fifth magneto-resistance effect element M5 pinned in the second direction D2, a sixth magneto-resistance effect element M6 pinned in the first direction, a seventh magneto-resistance effect element M7 pinned in the first direction D1, and an eighth magneto-resistance effect element M8 pinned in the second direction D2. An output of the first bridge circuit BC1 is corrected by an output of the second bridge circuit BC2.

Description

  The present invention relates to a magnetic sensor having a bridge circuit composed of a plurality of magnetoresistive elements.

  In recent years, a magnetic sensor using a magnetoresistive effect element that detects an external magnetic field can obtain current information, position information, angle information, and the like, and has been mounted on various electronic devices. In particular, a magnetic sensor for obtaining angle information is suitably used for a rotation sensor and an angle sensor because it can perform measurement without contact. This magnetic sensor uses a so-called spin-valve magnetoresistive element including a pinned magnetic layer pinned in a certain direction and a free magnetic layer whose magnetization direction rotates in the direction of an external magnetic field. There are many cases.

  As conventional example 1 of such a magnetic sensor, Patent Document 1 proposes a rotation angle sensor 800 in which a bridge circuit is configured using a plurality of magnetoresistive elements (spin valve elements) 810 as shown in FIG. Yes. 8A and 8B are diagrams for explaining the rotation angle sensor 800 of the conventional example 1. FIG. 8A is a perspective view of the rotation angle sensor 800, and FIG. 8B is a spin valve element (magnetoresistance). It is a perspective view explaining the film | membrane structure of an effect element 810. FIG.

  A rotation angle sensor 800 shown in FIG. 8A includes four spin valve elements 810 on a sensor holder 812, and a wiring board 811 for electrically connecting these spin valve elements 810 to form a bridge circuit. , Is composed of. In addition, as shown in FIG. 8B, the spin valve element 810 has a free layer (free layer) that is a ferromagnetic film whose magnetization can rotate with respect to an external magnetic field on a substrate 881 formed of a glass or silicon flat plate. (Magnetic layer) 810a, a nonmagnetic layer 810b serving as a spacer, a fixed layer (fixed magnetic layer) 810c that is a ferromagnetic film whose magnetization does not move by an external magnetic field, and an anti-strength that fixes the magnetization direction of the fixed layer 810c The magnetic layer 810d includes a CAP layer 810e that protects the antiferromagnetic layer 810d.

  As shown in FIG. 8A, the rotation angle sensor 800 configured as described above arranges four spin valve elements 810 in parallel to the xy plane and tilts adjacent ones by 90 °. And disposed on the wiring board 811. Further, the four spin valve elements 810 are arranged so that the magnetization direction of the fixed layer 810c is the magnetization direction MD shown in FIG. The rotation angle sensor 800 can obtain an output corresponding to the rotation angle θ of the rotating external magnetic field from the bridge circuit when a rotating external magnetic field is applied to the four spin valve elements 810, and generates a rotating external magnetic field. The rotation angle of the source can be measured.

  However, since the four spin valve elements 810 are mounted on the wiring substrate 811 so as to follow the magnetization direction MD, a plurality of processes are required for mounting, and the desired magnetization direction MD and the like due to mounting tolerances and the like. A deviation occurs in the magnetization direction of the mounted spin valve element 810. For this reason, the accuracy of the output from the bridge circuit is reduced, and even if the magnetoresistive effect element (spin valve element) 810 manufactured in the same batch is used, the characteristics of each magnetic sensor (rotation angle sensor) are not uniform. There was a problem that occurred.

  Accordingly, in order to solve the above-described problems, there has been proposed a magnetic sensor using a self-pinned magnetoresistive effect element capable of producing a plurality of magnetoresistive effect elements having different magnetization directions on the same substrate. . As a conventional example 2 of such a magnetic sensor, Patent Document 2 proposes a magnetic sensor as shown in FIG. FIG. 9 is a diagram for explaining the magnetic sensor of Conventional Example 2. FIG. 9A is a circuit diagram in which spin-valve giant magnetoresistive elements (SVGMR elements) constituting the magnetic sensor are bridge-connected. FIG. 9B is a cross-sectional view showing the structure of the film of the SVGMR element used in the magnetic sensor.

  As shown in FIG. 9A, the magnetic sensor of Conventional Example 2 has two bridge circuits A1 and B1, and each bridge circuit (A1, B1) has four SVGMR elements. (Aa, Ab, Ac, Ad) and SVGMR elements (Ba, Bb, Bc, Bd) are used. Then, eight SVGMR elements are manufactured on one substrate 910 and formed so as to have the magnetization direction MD shown in FIG.

  Further, as shown in FIG. 9B, the SVGMR element used has a base film 911, a first ferromagnetic layer 922 / an antiparallel coupling layer 923 / a second ferromagnetic layer 924 on a substrate 910. Laminated pinned layer (pinned magnetic layer) 912, nonmagnetic intermediate layer (nonmagnetic intermediate layer) 913, ferromagnetic layer 941 / ferromagnetic layer 942 laminated free layer (free magnetic layer) 914, protective layer 915 in this order It is formed by depositing a thin film. Then, by applying a magnetic field when the first ferromagnetic layer 922 and the second ferromagnetic layer 924 are formed, the magnetization direction MD of the fixed layer 912 can be matched with the direction of the applied magnetic field. That is, by forming SVGMR elements having different magnetization directions MD of the fixed layer 912 on the same substrate 910 four times, two bridge circuits A1 having four magnetization directions MD shown in FIG. 9A. And the magnetic sensor which has bridge circuit B1 can be obtained. As a result, the desired magnetization direction MD can be matched with the actual magnetization direction, the accuracy of output from the bridge circuit (A1, B1) is improved, and the same magnetization direction MD is produced in the same batch. Since the magnetoresistive effect element (self-pinning type) is used, the characteristic variation of each magnetic sensor can be reduced.

JP 2001-159542 A JP 2010-32484 A

  However, since the magnetoresistive effect element (SVGMR element) is manufactured a plurality of times (4 times in the conventional example 2), the temperature characteristics of each magnetoresistive effect element (SVGMR element) may not be the same. For this reason, the midpoint potential at normal temperature in the output from the bridge circuit (A1, B1) may drift greatly at low or high temperatures. The drift due to the temperature change of the midpoint potential is not constant depending on the combination of the SVGMR elements forming the bridge circuit (A1, B1), so that it is difficult to correct by a predetermined correction method, and the detection accuracy of the magnetic sensor is reduced. was there.

  The present invention solves the above-described problems, and an object thereof is to provide a magnetic sensor with improved detection accuracy.

  In order to solve this problem, the magnetic sensor of the present invention comprises a plurality of magnetoresistive elements in which a pinned magnetic layer and a free magnetic layer are laminated via a nonmagnetic material layer to form a bridge circuit. In the magnetic sensor, the pinned magnetic layer is formed by laminating a first magnetic layer and a second magnetic layer via a nonmagnetic intermediate layer, and the first magnetic layer and the second magnetic layer are magnetized in antiparallel. A fixed self-pinning type, wherein the bridge circuit comprises a first bridge circuit and a second bridge circuit for performing temperature compensation on the first bridge circuit, the first bridge circuit comprising: A first magnetoresistive element pinned in one direction; a second magnetoresistive element pinned in the first direction; a third magnetoresistive element pinned in a second direction; 4th magnet pinned in 2 directions A first connection portion is formed by connecting one end of the first magnetoresistive effect element and one end of the fourth magnetoresistive effect element, and one end of the second magnetoresistive effect element. A second connection portion is formed by connecting one end of the third magnetoresistive effect element, and a third end is formed by connecting the other end of the first magnetoresistive effect element and the other end of the third magnetoresistive effect element. A connecting portion is formed, a fourth connecting portion is formed by connecting the other end of the fourth magnetoresistive effect element and the other end of the second magnetoresistive effect element, and the first connecting portion and the first A predetermined potential is applied between the two connecting portions, and an output corresponding to changes in temperature and an external magnetic field is performed from the third connecting portion and the fourth connecting portion, and the second bridge circuit includes the second connecting circuit. A fifth magnetoresistive element pinned in the direction and a sixth magnet pinned in the first direction. And a seventh magnetoresistive effect element pinned in the first direction, and an eighth magnetoresistive effect element pinned in the second direction. A fifth connection portion is formed by connecting one end to one end of the eighth magnetoresistive effect element, and a sixth connection is formed by connecting one end of the sixth magnetoresistive effect element and one end of the seventh magnetoresistive effect element. A connecting portion is formed, and the other end of the eighth magnetoresistive effect element is formed by connecting the other end of the fifth magnetoresistive effect element to the other end of the seventh magnetoresistive effect element. And the other end of the sixth magnetoresistive element are connected to form an eighth connection portion, and a predetermined potential is applied between the fifth connection portion and the sixth connection portion to The output corresponding to only the temperature change is performed from the seventh connection portion and the eighth connection portion, and the second bridge. The output of the first bridge circuit is corrected by the output of the first circuit.

  According to this, the magnetic sensor of the present invention uses the output of the second bridge circuit to correct the output of the first bridge circuit whose output changes with the temperature change, so that The midpoint potential drift of the output can be corrected. Thereby, the detection accuracy of the magnetic sensor can be improved.

  In the magnetic sensor of the present invention, the bridge circuit includes a third bridge circuit and a fourth bridge circuit for performing temperature compensation for the third bridge circuit, and the third bridge circuit includes A ninth magnetoresistance effect element pinned in three directions; a tenth magnetoresistance effect element pinned in the third direction; an eleventh magnetoresistance effect element pinned in the fourth direction; A ninth magnetoresistive element pinned in four directions, and a ninth connection portion is formed by connecting one end of the ninth magnetoresistive effect element and one end of the twelfth magnetoresistive effect element, A tenth connection portion is formed by connecting one end of the tenth magnetoresistance effect element and one end of the eleventh magnetoresistance effect element, and the other end of the ninth magnetoresistance effect element and the eleventh magnetoresistance effect element. 11 is connected to the other end of the A continuation portion is formed to connect the other end of the twelfth magnetoresistive effect element and the other end of the tenth magnetoresistive effect element to form a twelfth connection portion; A predetermined potential is applied between the ten connection parts, and an output corresponding to changes in temperature and an external magnetic field is performed from the eleventh connection part and the twelfth connection part, and the fourth bridge circuit is connected to the third connection part. A thirteenth magnetoresistance effect element pinned in the direction, a fourteenth magnetoresistance effect element pinned in the fourth direction, a fifteenth magnetoresistance effect element pinned in the fourth direction, and the first A thirteenth magnetoresistive effect element pinned in three directions, and connecting one end of the thirteenth magnetoresistive effect element and one end of the sixteenth magnetoresistive effect element to form a thirteenth connection portion; One end of the fourteenth magnetoresistance effect element and the first A fourteenth connection portion is formed by connecting one end of the magnetoresistive effect element, and a fifteenth connection portion is formed by connecting the other end of the thirteenth magnetoresistive effect element and the other end of the fifteenth magnetoresistive effect element. A sixteenth connection portion is formed by connecting the other end of the sixteenth magnetoresistance effect element and the other end of the fourteenth magnetoresistance effect element, and the thirteenth connection portion and the fourteenth connection portion. A predetermined potential is applied between the fifteenth connection portion and the sixteenth connection portion, and an output corresponding only to a temperature change is performed. The output of the third bridge circuit is output by the output of the fourth bridge circuit. It is characterized by correction.

  According to this, the magnetic sensor of the present invention uses the output of the fourth bridge circuit to correct the output of the third bridge circuit whose output changes with the temperature change, so that the third bridge circuit due to the temperature change is corrected. The midpoint potential drift can be corrected. In addition, unlike the first bridge circuit pinned in the first direction and the second direction, the first bridge circuit has the third bridge circuit pinned in the third direction and the fourth direction. Sensing in an axial direction different from the axial direction to be sensed can be performed.

  The magnetic sensor of the present invention is characterized in that all of the magnetoresistive effect elements are formed on the same wafer.

  According to this, the magnetic sensor of this invention can form the magnetoresistive effect element of the same pinning direction at the same timing. For this reason, the temperature characteristics of the magnetoresistive elements having the same pinning direction are exactly the same. Thereby, the magnetoresistive effect element for measurement and the magnetoresistive effect element for temperature compensation have exactly the same temperature characteristics, and the midpoint potential drift of the output of the bridge circuit due to temperature change can be more accurately corrected. Thereby, the correction of the magnetic sensor is performed more accurately, and the measurement accuracy of the magnetic sensor can be further improved.

  The magnetic sensor of the present invention uses the output of the second bridge circuit to correct the output of the first bridge circuit whose output changes with the temperature change, so that the midpoint potential of the output of the first bridge circuit due to the temperature change is corrected. The drift can be corrected. Thereby, the detection accuracy of the magnetic sensor can be improved.

It is a figure explaining the magnetic sensor of 1st Embodiment of this invention, Comprising: It is a top surface block diagram of the chip element used for a magnetic sensor. It is a section lineblock diagram explaining the magnetoresistive effect element of the magnetic sensor concerning a 1st embodiment of the present invention. FIGS. 3A and 3B are diagrams illustrating a chip element of the magnetic sensor according to the first embodiment of the present invention, and FIGS. 3A and 3B are diagrams illustrating a pattern example of the magnetoresistive effect element illustrated in FIG. It is. FIG. 4A is a circuit diagram in which magnetoresistive elements of the magnetic sensor according to the first embodiment of the present invention are bridge-connected, FIG. 4A is a measurement bridge circuit, and FIG. 4B is temperature compensation. It is a bridge circuit for. It is a plane process drawing explaining the manufacturing process of the magnetoresistive effect element of the magnetic sensor concerning 1st Embodiment of this invention. It is a graph explaining the effect in the magnetic sensor of 1st Embodiment of this invention. FIGS. 7A and 7B illustrate a first modification of the magnetic sensor according to the first embodiment of the present invention, in which FIG. 7A is a bridge circuit for measurement, and FIG. 7B is a bridge for temperature compensation. Circuit. FIG. 8A is a perspective view of the rotation angle sensor 800, and FIG. 8B is a spin valve element (magnetoresistance effect element) 810. FIG. It is a perspective view explaining the film | membrane structure of this. FIG. 9A is a circuit diagram for explaining a magnetic sensor of Conventional Example 2 and FIG. 9A is a circuit diagram in which spin valve type giant magnetoresistive elements (SVGMR elements) constituting the magnetic sensor are bridge-connected. b) is a cross-sectional view showing the structure of the film of the SVGMR element used in the magnetic sensor.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

[First Embodiment]
FIG. 1 is a diagram illustrating the magnetic sensor according to the first embodiment of the present invention, and is a top view of the chip element 111 used in the magnetic sensor. In FIG. 1, the sensitivity axis direction of each magnetoresistive effect element M is shown. Detailed patterns of the magnetoresistive effect element M are omitted.

  The magnetic sensor according to the first embodiment of the present invention is packaged with a thermosetting synthetic resin in which the chip element 111 shown in FIG. 1 and a lead terminal for taking out a signal from the chip element 111 are electrically connected. Have been More specifically, each of the source pad Vdd, the ground pad GND, the signal pad Sc, and the signal pad Ss shown in FIG. 1 and a lead terminal drawn out of the package are wire-bonded in the package. Have been electrically connected.

  Further, as shown in FIG. 1, the magnetic sensor includes 16 magnetoresistive elements M in one chip element 111, and each magnetoresistive element M is connected to a source pad by a wiring pattern P1. Vdd, ground pad GND, signal pad Sc, and signal pad Ss are appropriately connected. In addition, four bridge circuits are configured in one chip element 111. The bridge circuit will be described in detail later.

  First, the magnetoresistive element M will be described. FIG. 2 is a cross-sectional configuration diagram illustrating a layer configuration of the magnetoresistive element M according to the magnetic sensor of the first embodiment of the present invention. FIG. 3A and FIG. 3B are diagrams showing pattern examples of the magnetoresistive effect element M shown in FIG.

  As shown in FIG. 2, the magnetoresistive effect element M is formed on a substrate 19 made of silicon or the like, and is formed of NiFeCr or Cr, and is pinned in a certain direction through a seed layer S8. The nonmagnetic material layer 3, the free magnetic layer 4 whose magnetization direction rotates in the direction of the external magnetic field, and the protective layer H7 are stacked in this order. Each layer constituting the magnetoresistive element M is formed by sputtering, for example.

  Further, in the magnetoresistive element M, for example, as shown in FIG. 3A, a plurality of element portions Ma extending in a strip shape in the X direction are patterned with an interval in the Y direction. And between the Y1 side edge part of each element part Ma and between Y2 side edge part is connected by the electroconductive part Mc, it is a meander-shaped pattern. In the magnetoresistive element M, for example, as shown in FIG. 3B, a plurality of element parts Ma extending in a strip shape in the Y direction are patterned at intervals in the X direction, and are connected by the conductive part Mc. It has become a meander-shaped pattern. The conductive portion Mc may be non-magnetic or magnetic, but preferably has a low electrical resistance.

  As shown in FIG. 2, the pinned magnetic layer 2 of the magnetoresistive element M has an SFP (Synthetic Ferri Pin) structure in which a first magnetic layer 12 and a second magnetic layer 22 are stacked with a nonmagnetic intermediate layer 42 interposed therebetween. It is. The fixed magnetization direction (arrow shown in FIG. 2) of the first magnetic layer 12 and the fixed magnetization direction (arrow shown in FIG. 2) of the second magnetic layer 22 are magnetization-fixed antiparallel. This SFP structure results in a so-called self-pinned magnetoresistive element M.

  The nonmagnetic material layer 3 of the magnetoresistive effect element M is made of a nonmagnetic conductive material such as Cu (copper). The free magnetic layer 4 is made of a soft magnetic material such as NiFe, CoFe, or CoFeNi, and has a single layer structure or a laminated structure. Further, Ta (tantalum) or the like is used for the protective layer H7.

  In the magnetoresistive effect element M configured as described above, the pinned magnetic layer 2 is formed by the self-pinning structure shown in FIG. By applying, the sensitivity axis direction can be aligned in an arbitrary direction. For this reason, it is possible to form a plurality of magnetoresistive elements M having different sensitivity axis directions on the same substrate 19 by performing the film formation a plurality of times. This self-pinned structure, once fixed in magnetization, has the following magnetoresistive effect element due to strong RKKY (Rudermann, Kittel, Kasuya, Yoshida) interaction generated between the first magnetic layer 12 and the second magnetic layer 22. Even when the M pinned magnetic layer 2 is formed in a magnetic field, the magnetization pinned direction of the pinned magnetic layer 2 already formed does not fluctuate.

  Next, the bridge circuit will be described. 4 is a circuit diagram in which the magnetoresistive effect element M related to the magnetic sensor according to the first embodiment of the present invention is bridge-connected, and FIG. 4A is a measurement bridge circuit, and FIG. ) Is a bridge circuit for temperature compensation. FIG. 4 shows the sensitivity axis direction of each magnetoresistive element M. The sensitivity axis direction coincides with the magnetization direction of the pinned magnetic layer 2 (second magnetic layer 22).

  The four bridge circuits of the first embodiment of the present invention include a first bridge circuit BC1 using four magnetoresistive elements M, a second bridge circuit BC2 using four magnetoresistive elements M, The third bridge circuit BC3 using the magnetoresistive effect element M and the fourth bridge circuit BC4 using the four magnetoresistive effect elements M are configured.

  First, as shown in FIG. 4A, the first bridge circuit BC1 includes a first magnetoresistive element M1 pinned in the first direction D1 (Y1 direction shown in FIG. 1), and a first direction D1. The second magnetoresistive element M2 pinned, the third magnetoresistive element M3 pinned in the second direction D2 (Y2 direction shown in FIG. 1), and the fourth pinned in the second direction D2. And a magnetoresistive element M4. That is, as shown in FIG. 1, the sensitivity axis direction (first direction D1) of the first magnetoresistive effect element M1 and the second magnetoresistive effect element M2, and the third magnetoresistive effect element M3 and the fourth magnetoresistive effect element. It is arranged antiparallel to the sensitivity axis direction (second direction D2) of M4. The four magnetoresistive elements M use the pattern shown in FIG.

  Further, as shown in FIG. 4A, a first connection portion CN1 is formed by connecting one end of the first magnetoresistive effect element M1 and one end of the fourth magnetoresistive effect element M4, and the second magnetoresistive effect. A second connection portion CN2 is formed by connecting one end of the element M2 and one end of the third magnetoresistive effect element M3, and the other end of the first magnetoresistive effect element M1 and the other end of the third magnetoresistive effect element M3. Is connected to form the third connection portion CN3, and the other end of the fourth magnetoresistance effect element M4 and the other end of the second magnetoresistance effect element M2 are connected to form the fourth connection portion CN4.

  In the first bridge circuit BC1, a predetermined potential is applied between the first connection part CN1 and the second connection part CN2, and the temperature and the external magnetic field are changed from the third connection part CN3 and the fourth connection part CN4. Corresponding output is performed.

  For example, if an external magnetic field acts on the magnetic sensor having the first bridge circuit BC1 in the X1 direction shown in FIG. 1, the external magnetic field is applied to each sensitivity axis direction (first direction D1 and second direction D2). ) Acts from a direction orthogonal to the magnetoresistive effect element M (M1, M2, M3, M4), and the third resistance CN3 and the fourth connection shown in FIG. The midpoint potential of the part CN4 does not change (the sensor output is zero).

  For example, if the external magnetic field rotates and acts in the Y1 direction shown in FIG. 1, the sensitivity axis direction (first direction D1) of the first magnetoresistive element M1 and the second magnetoresistive element M2 and the external magnetic field Therefore, in the third magnetoresistive effect element M3 and the fourth magnetoresistive effect element M4, the sensitivity axis direction (second direction D2) and the direction of the external magnetic field are different from each other. Since it is the opposite direction, an electrical resistance value becomes large. For this reason, the midpoint potential of the third connection part CN3 and the fourth connection part CN4 fluctuates with opposite signs, and the difference value of this fluctuation is output as the output value of the magnetic sensor. This difference value varies with the direction of the external magnetic field, and a value corresponding to the direction of the external magnetic field can be obtained.

  Next, as shown in FIG. 1 and FIG. 4B, the second bridge circuit BC2 is pinned in the first direction D1 with the fifth magnetoresistive element M5 pinned in the second direction D2. The sixth magnetoresistance effect element M6, the seventh magnetoresistance effect element M7 pinned in the first direction D1, and the eighth magnetoresistance effect element M8 pinned in the second direction D2. . That is, as shown in FIG. 1, the sensitivity axis direction (first direction D1) of the sixth magnetoresistive effect element M6 and the seventh magnetoresistive effect element M7, and the fifth magnetoresistive effect element M5 and the eighth magnetoresistive effect element. It is arranged antiparallel to the sensitivity axis direction of M8 (second direction D2). The four magnetoresistive elements M also use the pattern shown in FIG.

  Further, as shown in FIG. 4B, a fifth connection portion CN5 is formed by connecting one end of the fifth magnetoresistive element M5 and one end of the eighth magnetoresistive element M8, and the sixth magnetoresistive effect. A sixth connection portion CN6 is formed by connecting one end of the element M6 and one end of the seventh magnetoresistive effect element M7, and the other end of the fifth magnetoresistive effect element M5 and the other end of the seventh magnetoresistive effect element M7. Is connected to form the seventh connection portion CN7, and the other end of the eighth magnetoresistance effect element M8 and the other end of the sixth magnetoresistance effect element M6 are connected to form an eighth connection portion CN8.

  In the second bridge circuit BC2, a predetermined potential is applied between the fifth connection portion CN5 and the sixth connection portion CN6, and an output corresponding only to a temperature change from the seventh connection portion CN7 and the eighth connection portion CN8. Is configured to be performed.

  For example, if an external magnetic field acts on the magnetic sensor having the second bridge circuit BC2 in the X1 direction shown in FIG. 1, the external magnetic field is applied to each sensitivity axis direction (first direction D1 and second direction D2). ) From the direction orthogonal to the magnetoresistive effect element M (M5, M6, M7, M8), the electric resistance values are equal, and the seventh connection portion CN7 and the eighth connection shown in FIG. The midpoint potential of the part CN8 does not change (the sensor output is zero).

  For example, if the external magnetic field rotates and acts in the Y1 direction shown in FIG. 1, the sensitivity axis direction (first direction D1) of the sixth magnetoresistive element M6 and the seventh magnetoresistive element M7 and the external magnetic field Therefore, in the fifth magnetoresistive effect element M5 and the eighth magnetoresistive effect element M8, the sensitivity axis direction (second direction D2) and the direction of the external magnetic field are different from each other. Since it is the opposite direction, an electrical resistance value becomes large. However, in the second bridge circuit BC2, since the variation of the electrical resistance value in the magnetoresistive effect element M distributed by the seventh connection unit CN7 and the eighth connection unit CN8 is the same amount of variation, the seventh connection unit CN7 and the eighth connection unit CN8. Although the midpoint potential of the connection portion CN8 varies, the difference value between the seventh connection portion CN7 and the eighth connection portion CN8 is not output (the sensor output is zero). Thus, the second bridge circuit BC2 is configured not to be affected by the direction of the external magnetic field.

  On the other hand, since the resistance value of the magnetoresistive effect element M varies depending on the temperature, the seventh connection portion CN7 and the magnetoresistive effect element M at the low temperature and the high temperature are different due to a slight temperature characteristic difference between the magnetoresistive effect elements M. The midpoint potential of the eighth connection CN8 varies, and the difference value of the variation is output as the output value of the magnetic sensor. Similarly, in the first bridge circuit BC1, the output value at the low temperature and at the high temperature fluctuates.

  Accordingly, the output of the first bridge circuit BC1 whose output changes with a change in temperature is corrected using the output of the second bridge circuit BC2, so that the midpoint potential drift of the output of the first bridge circuit BC1 due to the temperature change is corrected. Can be corrected. Thereby, the detection accuracy of the magnetic sensor can be improved.

  Further, the magnetic sensor according to the first embodiment of the present invention further performs temperature compensation for the third bridge circuit BC3 and the third bridge circuit BC3 as in the combination of the first bridge circuit BC1 and the second bridge circuit BC2 described above. A fourth bridge circuit BC4.

  First, the third bridge circuit BC3 includes a ninth magnetoresistive element M9 pinned in the third direction D3 (X1 direction shown in FIG. 1) and a tenth magnetoresistive element pinned in the third direction D3. M10, an eleventh magnetoresistive element M11 pinned in the fourth direction D4 (X2 direction shown in FIG. 1), and a twelfth magnetoresistive element M12 pinned in the fourth direction D4. ing. That is, as shown in FIG. 1, the sensitivity axis direction (third direction D3) of the ninth magnetoresistance effect element M9 and the tenth magnetoresistance effect element M10, and the eleventh magnetoresistance effect element M11 and the twelfth magnetoresistance effect element. It is arranged antiparallel to the sensitivity axis direction of M12 (fourth direction D4). The four magnetoresistive elements M also use the pattern shown in FIG. These four magnetoresistive elements M use the pattern shown in FIG.

  Further, as shown in FIG. 4A, a ninth connection portion CN9 is formed by connecting one end of the ninth magnetoresistance effect element M9 and one end of the twelfth magnetoresistance effect element M12, and the tenth magnetoresistance effect is formed. A tenth connection portion CN10 is formed by connecting one end of the element M10 and one end of the eleventh magnetoresistive element M11, and the other end of the ninth magnetoresistive element M9 and the other end of the eleventh magnetoresistive element M11. Is connected to form the eleventh connection portion CN11, and the other end of the twelfth magnetoresistance effect element M12 and the other end of the tenth magnetoresistance effect element M10 are connected to form a twelfth connection portion CN12.

  Then, a predetermined potential is applied between the ninth connection portion CN9 and the tenth connection portion CN10, and an output corresponding to changes in temperature and external magnetic field is performed from the eleventh connection portion CN11 and the twelfth connection portion CN12. It is configured. The output value of the third bridge circuit BC3 is an output value out of phase with respect to the first bridge circuit BC1.

  In the third bridge circuit BC3, similarly to the first bridge circuit BC1, the difference between the output values from the eleventh connection part CN11 and the twelfth connection part CN12 varies with the direction of the external magnetic field, and the external magnetic field A value corresponding to the direction can be obtained.

  Finally, the fourth bridge circuit BC4 is pinned in the fourth direction D4 and the thirteenth magnetoresistive element M13 pinned in the third direction D3, as shown in FIGS. 1 and 4B. The fourteenth magnetoresistance effect element M14, the fifteenth magnetoresistance effect element M15 pinned in the fourth direction D4, and the sixteenth magnetoresistance effect element M16 pinned in the third direction D3. . That is, as shown in FIG. 1, the sensitivity axis direction (third direction D3) of the thirteenth magnetoresistive element M13 and the sixteenth magnetoresistive element M16, the fourteenth magnetoresistive element M14, and the fifteenth magnetoresistive element It is arranged antiparallel to the sensitivity axis direction (fourth direction D4) of M15. These four magnetoresistive elements M use the pattern shown in FIG.

  4B, one end of the thirteenth magnetoresistive effect element M13 and one end of the sixteenth magnetoresistive effect element M16 are connected to form a thirteenth connection portion CN13. One end of the element M14 and one end of the fifteenth magnetoresistive effect element M15 are connected to form a fourteenth connection portion CN14. The other end of the thirteenth magnetoresistive effect element M13 and the other end of the fifteenth magnetoresistive effect element M15 Are connected to form the fifteenth connection portion CN15, and the other end of the sixteenth magnetoresistive effect element M16 and the other end of the fourteenth magnetoresistive effect element M14 are connected to form a sixteenth connection portion CN16.

  A predetermined potential is applied between the thirteenth connection portion CN13 and the fourteenth connection portion CN14, and an output corresponding to only a temperature change is performed from the fifteenth connection portion CN15 and the sixteenth connection portion CN16. ing.

  Similar to the second bridge circuit BC2, the fourth bridge circuit BC4 has a configuration in which the difference between the output values from the fifteenth connection unit CN15 and the sixteenth connection unit CN16 is not affected by the direction of the external magnetic field. Yes. On the other hand, in the fourth bridge circuit BC4, the midpoint potentials of the fifteenth connection portion CN15 and the sixteenth connection portion CN16 fluctuate at low temperatures and high temperatures due to slight differences in temperature characteristics of the magnetoresistive elements M. The difference value of the fluctuation is output as the output value of the magnetic sensor. Similarly, in the third bridge circuit BC3, the output values at low temperatures and high temperatures are fluctuating.

  Thus, the output of the third bridge circuit BC3 whose output changes with temperature change is corrected using the output of the fourth bridge circuit BC4, thereby correcting the midpoint potential drift of the third bridge circuit BC3 due to temperature change. can do. Moreover, unlike the first bridge circuit BC1 pinned in the first direction D1 and the second direction D2, the third bridge circuit BC3 is pinned in the third direction D3 and the fourth direction D4. Thus, sensing in an axial direction different from the axial direction sensed by the first bridge circuit BC1 can be performed.

  Next, in the chip element 111 relating to the magnetic sensor of the first embodiment of the present invention, how to form a plurality of magnetoresistive effect elements M on the same substrate 19 will be described with reference to FIGS. Explained. FIG. 5 is a plan process diagram for explaining a manufacturing process of the magnetoresistive element M of the magnetic sensor according to the first embodiment of the present invention. In FIG. 5, a plurality of chip elements 111 are shown. However, in actual manufacturing, a large number of chip elements 111 are formed on the wafer 19 (substrate 19), and in the final process, each chip element 111 is cut. A large number of chip elements 111 are obtained at one time. For the sake of clarity, the source pad Vdd, the ground pad GND, the signal pad Sc, and the signal pad Ss, which are created in a later step, are indicated by two-dot chain lines. The sensitivity axis directions (first direction D1, second direction D2, third direction D3, and fourth direction D4) are indicated by arrows.

  First, a silicon wafer 19 is prepared. As shown in FIG. 5A, a first magnetoresistive element M1, a second magnetoresistive element M2, and a sixth magnetoresistive element M6 are formed on the wafer 19. Then, a seventh magnetoresistance effect element M7 is formed. At this time, the pinned magnetic layer 2 having a self-pinned structure is formed by film formation in a magnetic field, and the fixed magnetization direction of each pinned magnetic layer 2 is directed to the first direction D1.

  Next, as shown in FIG. 5B, the third magnetoresistive element M3, the fourth magnetoresistive element M4, the fifth magnetoresistive element M5, and the eighth magnetoresistive element 8 are formed in the empty space on the wafer 19. A magnetoresistive element M8 is formed. At that time, the fixed magnetization direction of each fixed magnetic layer 2 is set to be in the second direction D2.

  Next, as shown in FIG. 5C, the ninth magnetoresistive effect element M9, the tenth magnetoresistive effect element M10, the thirteenth magnetoresistive effect element M13, and the sixteenth magnetoresistive effect element M9 A magnetoresistive element M16 is formed. At that time, the pinned magnetization direction of each pinned magnetic layer 2 is set to be in the third direction D3.

  Next, as shown in FIG. 5D, the eleventh magnetoresistive effect element M11, the twelfth magnetoresistive effect element M12, the fourteenth magnetoresistive effect element M14, and the fifteenth magnetoresistive effect element M11 are formed in the space on the wafer 19. A magnetoresistive element M15 is formed. At that time, the fixed magnetization direction of each fixed magnetic layer 2 is set to be in the fourth direction D4.

  Thereafter, each of the formed magnetoresistive effect elements M is etched using a photolithography method to form a meander-shaped pattern as shown in FIG. Then, after forming the wiring pattern P1, the source pad Vdd, the ground pad GND, the signal pad Sc, and the signal pad Ss, finally, the chip element 111 is obtained by cutting by dicing. In this way, one chip element 111 in which all of the magnetoresistive effect element M is formed on the same wafer 19 (substrate 19) can be obtained.

  As described above, the magnetoresistive effect elements M in the same pinning direction are formed at the same timing. For this reason, the temperature characteristics of the magnetoresistive elements M having the same pinning direction are exactly the same. For this reason, the magnetoresistive element M for measurement and the magnetoresistive element M for temperature compensation have exactly the same temperature characteristics, and the midpoint potential drift of the output of the bridge circuit due to temperature change can be more accurately corrected. Thereby, the correction of the magnetic sensor is performed more accurately, and the measurement accuracy of the magnetic sensor can be further improved.

  In addition, since many chip elements 111 obtained from the same wafer 19 have exactly the same temperature characteristics of the magnetoresistive effect elements M having the same pinning direction, each magnetic element using the same batch of chip elements 111 is used. Variations in sensor characteristics can be reduced.

  Moreover, since the magnetoresistive element M for temperature compensation can be manufactured in the same process for manufacturing the magnetoresistive element M for measurement, the chip element 111 can be manufactured without increasing the number of processes. Can do. As a result, the process is not complicated and the manufacturing cost can be increased.

  The effects of the magnetic sensor according to the first embodiment of the present invention configured as described above will be described below together with verification results. FIG. 6 is a graph for explaining the effect of the magnetic sensor according to the first embodiment of the present invention. The horizontal axis in FIG. 6 represents the environmental temperature of the magnetic sensor, and the vertical axis represents the drift amount (V) of the midpoint potential. Also, the result RA1 in the figure is the result of the magnetic sensor according to the first embodiment of the present invention, and the result RC1 in the figure is a comparative example that does not have the second bridge circuit BC2 and the fourth bridge circuit BC4. It is a result of a magnetic sensor.

  Since the magnetic sensor of the first embodiment of the present invention includes the second bridge circuit BC2 that outputs only in response to a temperature change, the output changes with a temperature change using the output of the second bridge circuit BC2. By correcting the output of the first bridge circuit BC1, the midpoint potential drift of the output of the first bridge circuit BC1 due to temperature change can be corrected. Thereby, the detection accuracy of the magnetic sensor can be improved.

  Further, since the fourth bridge circuit BC4 that outputs only corresponding to the temperature change is provided, the output of the third bridge circuit BC3 whose output changes with the temperature change is corrected using the output of the fourth bridge circuit BC4. Thus, the midpoint potential drift of the third bridge circuit BC3 due to the temperature change can be corrected. As is clear from the results shown in FIG. 6, this is a drastic improvement in the midpoint potential drift in the temperature change, and an improvement to a state where there is almost no drift.

  Moreover, unlike the first bridge circuit BC1 pinned in the first direction D1 and the second direction D2, the third bridge circuit BC3 is pinned in the third direction D3 and the fourth direction D4. Thus, sensing in an axial direction different from the axial direction sensed by the first bridge circuit BC1 can be performed.

  Further, since all the magnetoresistive effect elements M are formed on the same wafer 19, the magnetoresistive effect elements M in the same pinning direction are formed at the same timing. For this reason, the temperature characteristics of the magnetoresistive elements M having the same pinning direction are exactly the same. Thereby, the magnetoresistive effect element M for measurement and the magnetoresistive effect element M for temperature compensation have exactly the same temperature characteristics, and the midpoint potential drift of the output of the bridge circuit due to temperature change can be more accurately corrected. Thereby, the correction of the magnetic sensor is performed more accurately, and the measurement accuracy of the magnetic sensor can be further improved.

  In addition, this invention is not limited to the said embodiment, For example, it can deform | transform and implement as follows, These embodiments also belong to the technical scope of this invention.

  FIG. 7 is a diagram for explaining a first modification of the magnetic sensor according to the first embodiment of the present invention. FIG. 7A is a bridge circuit for measurement, and FIG. It is a bridge circuit for compensation.

<Modification 1>
In the first embodiment, the two-axis bridge circuit having the first direction D1 and the second direction D2, and the third direction D3 and the fourth direction D4 is used. However, the present invention is not limited to this. For example, as shown in FIG. 7, in addition to the third bridge circuit BC3 and the fourth bridge circuit BC4 having the third direction D3 and the fourth direction D4, the fifth bridge having the fifth direction D5 and the sixth direction D6. A chip element may be formed using the circuit BC5 and the sixth bridge circuit BC6, and the seventh bridge circuit BC7 and the eighth bridge circuit BC8 having the seventh direction D7 and the eighth direction D8. At this time, the fifth direction D5, the sixth direction D6, the seventh direction D7, and the eighth direction D8 are inclined by 45 degrees with respect to the X1-X2 direction or the Y1-Y2 direction in FIG. Thereby, the magnetic sensor can obtain an output value with higher sensitivity.

<Modification 2>
Alternatively, the first bridge circuit BC1 and the second bridge circuit BC2 may be used alone, or the third bridge circuit BC3 and the fourth bridge circuit BC4 may be used.

<Modification 3>
Further, for example, a half bridge circuit for measurement using the first magnetoresistive effect element M1 and the third magnetoresistive effect element M3, and for temperature compensation using the fifth magnetoresistive effect element M5 and the seventh magnetoresistive effect element M7. The half-bridge circuit may be used.

  The present invention is not limited to the above-described embodiment, and can be modified as appropriate without departing from the scope of the object of the present invention.

M magnetoresistive effect element M1 1st magnetoresistive effect element M2 2nd magnetoresistive effect element M3 3rd magnetoresistive effect element M4 4th magnetoresistive effect element M5 5th magnetoresistive effect element M6 6th magnetoresistive effect element M7 7th Magnetoresistive effect element M8 8th magnetoresistive effect element M9 9th magnetoresistive effect element M10 10th magnetoresistive effect element M11 11th magnetoresistive effect element M12 12th magnetoresistive effect element M13 13th magnetoresistive effect element M14 14th magnetism Resistive effect element M15 15th magnetoresistive effect element M16 16th magnetoresistive effect element 2 Fixed magnetic layer 12 1st magnetic layer 22 2nd magnetic layer 42 Nonmagnetic intermediate layer 3 Nonmagnetic material layer 4 Free magnetic layer 19 Wafer (substrate)
BC1 1st bridge circuit BC2 2nd bridge circuit BC3 3rd bridge circuit BC4 4th bridge circuit CN1 1st connection part CN2 2nd connection part CN3 3rd connection part CN4 4th connection part CN5 5th connection part CN6 6th connection part CN7 7th connection section CN8 8th connection section CN9 9th connection section CN10 10th connection section CN11 11th connection section CN12 12th connection section CN13 13th connection section CN14 14th connection section CN15 15th connection section CN16 16th connection section D1 1st direction D2 2nd direction D3 3rd direction D4 4th direction

Claims (3)

In a magnetic sensor comprising a plurality of magnetoresistive effect elements in which a pinned magnetic layer and a free magnetic layer are laminated via a nonmagnetic material layer to form a bridge circuit,
The pinned magnetic layer is a self-pinning type in which a first magnetic layer and a second magnetic layer are laminated via a nonmagnetic intermediate layer, and the first magnetic layer and the second magnetic layer are magnetization-fixed antiparallel. And
The bridge circuit includes a first bridge circuit and a second bridge circuit for performing temperature compensation on the first bridge circuit,
The first bridge circuit includes a first magnetoresistive element pinned in a first direction, a second magnetoresistive element pinned in the first direction, and a third pinned in a second direction. A magnetoresistive element, and a fourth magnetoresistive element pinned in the second direction,
A first connection portion is formed by connecting one end of the first magnetoresistance effect element and one end of the fourth magnetoresistance effect element,
A second connection portion is formed by connecting one end of the second magnetoresistance effect element and one end of the third magnetoresistance effect element;
A third connection portion is formed by connecting the other end of the first magnetoresistance effect element and the other end of the third magnetoresistance effect element;
A fourth connecting portion is formed by connecting the other end of the fourth magnetoresistive element and the other end of the second magnetoresistive element;
A predetermined potential is applied between the first connection part and the second connection part, and an output corresponding to a change in temperature and an external magnetic field is performed from the third connection part and the fourth connection part,
The second bridge circuit is pinned in the first direction with a fifth magnetoresistive element pinned in the second direction, a sixth magnetoresistive element pinned in the first direction, and A seventh magnetoresistive element, and an eighth magnetoresistive element pinned in the second direction,
A fifth connecting portion is formed by connecting one end of the fifth magnetoresistive element and one end of the eighth magnetoresistive element;
A sixth connection portion is formed by connecting one end of the sixth magnetoresistance effect element and one end of the seventh magnetoresistance effect element;
A seventh connecting portion is formed by connecting the other end of the fifth magnetoresistive element and the other end of the seventh magnetoresistive element;
An eighth connection portion is formed by connecting the other end of the eighth magnetoresistive element and the other end of the sixth magnetoresistive element;
A predetermined potential is applied between the fifth connection part and the sixth connection part, and an output corresponding only to a temperature change is performed from the seventh connection part and the eighth connection part,
A magnetic sensor, wherein the output of the first bridge circuit is corrected by the output of the second bridge circuit. The bridge circuit includes a third bridge circuit and a fourth bridge circuit for performing temperature compensation for the third bridge circuit,
The third bridge circuit includes a ninth magnetoresistive element pinned in the third direction, a tenth magnetoresistive element pinned in the third direction, and an eleventh pinned in the fourth direction. A magnetoresistive effect element and a twelfth magnetoresistive effect element pinned in the fourth direction,
A ninth connection portion is formed by connecting one end of the ninth magnetoresistance effect element and one end of the twelfth magnetoresistance effect element,
A tenth connection portion is formed by connecting one end of the tenth magnetoresistive effect element and one end of the eleventh magnetoresistive effect element,
An eleventh connection portion is formed by connecting the other end of the ninth magnetoresistive element and the other end of the eleventh magnetoresistive element,
A twelfth connecting portion is formed by connecting the other end of the twelfth magnetoresistive element and the other end of the tenth magnetoresistive element;
A predetermined potential is applied between the ninth connection part and the tenth connection part, and an output corresponding to a change in temperature and an external magnetic field is performed from the eleventh connection part and the twelfth connection part,
The fourth bridge circuit is pinned in the fourth direction, a thirteenth magnetoresistive element pinned in the third direction, a fourteenth magnetoresistive element pinned in the fourth direction, and the fourth direction. A fifteenth magnetoresistance effect element and a sixteenth magnetoresistance effect element pinned in the third direction,
A thirteenth connection portion is formed by connecting one end of the thirteenth magnetoresistance effect element and one end of the sixteenth magnetoresistance effect element,
A fourteenth connection portion is formed by connecting one end of the fourteenth magnetoresistive effect element and one end of the fifteenth magnetoresistive effect element;
A fifteenth connection portion is formed by connecting the other end of the thirteenth magnetoresistance effect element and the other end of the fifteenth magnetoresistance effect element;
A sixteenth connection portion is formed by connecting the other end of the sixteenth magnetoresistance effect element and the other end of the fourteenth magnetoresistance effect element;
A predetermined potential is applied between the thirteenth connection portion and the fourteenth connection portion, and an output corresponding only to a temperature change is performed from the fifteenth connection portion and the sixteenth connection portion,
The magnetic sensor according to claim 1, wherein the output of the third bridge circuit is corrected by the output of the fourth bridge circuit.   The magnetic sensor according to claim 1, wherein all of the magnetoresistive effect elements are formed on the same wafer.