JP5045617B2 - Magnetic sensor - Google Patents

Description

  The present invention relates to a magnetic sensor using a magnetoresistive effect element.

  Conventionally, a magnetoresistive effect element such as a ferromagnetic magnetic element (MR element), a giant magnetoresistive effect element (GMR element), or a magnetic tunnel effect element (TMR element) has been used as a magnetic field detection element. There is known a magnetic sensor configured to generate an output value corresponding to an external magnetic field applied to the magnetoresistive element based on the resistance value.

  Incidentally, the resistance value of the magnetoresistive effect element changes depending on the element temperature. For this reason, the output value of the magnetic sensor changes depending on the temperature of the magnetoresistive element even if the magnetic field to be detected is the same. Therefore, in order to detect the magnetic field (magnitude) with high accuracy, it is necessary to compensate for such temperature dependent characteristics.

On the other hand, in the magnetic sensor device described in Japanese Patent Laid-Open No. 6-77558 (Patent Document 1), a temperature sensor is disposed in the vicinity of the magnetoresistive effect element, and a voltage and a temperature that are output values of the magnetic sensor. (Temperature dependence characteristics) is measured in advance and stored in the memory, and the reference voltage is determined based on the actual temperature detected by the temperature sensor and the relationship stored in the memory. By amplifying and outputting the difference between the actually output voltage and the determined reference voltage, the temperature dependent characteristic of the magnetic sensor is compensated.
Japanese Patent Laid-Open No. 6-77558

  On the other hand, the output value of a highly sensitive magnetic sensor changes under the influence of geomagnetism. In addition, geomagnetism varies with time. For this reason, the temperature-dependent characteristics stored in the memory of the magnetic sensor device must be measured within a predetermined short time period during which it is guaranteed that the geomagnetism does not change, and therefore the magnetoresistance effect during the measurement The element must be heated or cooled within a short time.

  However, if the magnetoresistive effect element is heated by a general heating / cooling device, not only the magnetoresistive effect element but also the entire magnetic sensor including the substrate is heated / cooled. Due to the large heat capacity of the magnetic sensor, the heating / cooling time becomes longer and the geomagnetism may change during the measurement of the temperature-dependent characteristics. As a result, the reliability of the temperature-dependent characteristics stored in the memory decreases. As a result, there is a problem that compensation for temperature dependent characteristics cannot be made with high accuracy. On the other hand, it is conceivable to measure the temperature-dependent characteristics in an environment from which the influence of geomagnetism is removed, but a device (magnetic field canceller) for forming such an environment is extremely expensive. There is also a problem that the manufacturing cost of the sensor increases.

  Accordingly, one of the objects of the present invention is to provide a magnetic sensor capable of measuring temperature-dependent characteristics at a low cost within a short time and with high accuracy, and to compensate temperature-dependent characteristics with high accuracy. Another object of the present invention is to provide a temperature compensation characteristic compensation method for a magnetic sensor.

  Another object of the present invention is a single-chip magnetic sensor that outputs the magnetic sensor without using a connection wire such as an Au wire that connects the magnetic sensor and the outside of the magnetic sensor. It is an object of the present invention to provide a magnetic sensor capable of generating a signal.

  Another object of the present invention is to generate an output signal based on the resistance change of the magnetoresistive effect element, obtain temperature characteristic data of the magnetoresistive effect element, initialize the magnetization of the free layer of the magnetoresistive effect element, or It is an object of the present invention to provide a magnetic sensor in which a control circuit unit for applying an external magnetic field for functional inspection of a resistance effect element is not easily affected by external noise.

  Furthermore, another object of the present invention is to provide a magnetic sensor having a structure suitable for easily and reliably fixing magnetization of pinned layers of a plurality of magnetoresistive elements in the same direction.

A magnetic sensor disclosed in the present specification includes a plurality of magnetoresistive elements formed on an upper surface of a layer stacked on a substrate, and a plurality of heating elements that generate heat when energized, and the plurality of magnetoresistive elements A magnetic sensor for generating an output value corresponding to an external magnetic field applied to the magnetoresistive element based on a resistance value of the effect element, wherein the plurality of heating elements each have a heating value substantially equal to each other. When the heat is generated, the temperature of the plurality of magnetoresistive effect elements is substantially equal to each other, and the temperature of the upper surface of the layer on which the plurality of magnetoresistive effect elements are formed is non-uniform. It is a feature. In this case, the magnetoresistive element includes an MR element, a GMR element, a TMR element, and the like.

  According to this, since the whole magnetic sensor including the substrate is not heated until the same temperature is reached, the plurality of magnetoresistive elements are heated so as to have substantially the same temperature (a temperature different from the substrate temperature). The time required for heating and cooling the magnetoresistive effect element can be shortened, and the temperature-dependent characteristics of the magnetoresistive effect element can be measured within a period in which the same geomagnetism is applied.

  In this case, the plurality of magnetoresistive elements constitute a plurality of island-shaped element groups in which a plurality of elements having the same magnetic field detection direction are arranged close to each other on the upper surface of the layer, One may be formed above or below each of the plurality of element groups. According to this, since the heating element can mainly heat the magnetoresistive effect element, the time required for heating and cooling can be further shortened.

  In addition, the heating element has the same magnetic field in the same direction as or substantially perpendicular to the magnetic field detection direction of each magnetoresistive element formed above or below each heating element by the energization. It is preferable that the coil be formed by a coil (heating coil) that can be applied to each magnetoresistive element. In this case, a magnetic field in substantially the same direction as the magnetic field detection direction of the magnetoresistive effect element can be used as an inspection magnetic field for determining whether the magnetic sensor normally detects the magnetic field, and the magnetic field detection direction of the magnetoresistive effect element Can be used as a magnetic field for initializing the free layer of the magnetoresistive element.

  According to this, a heating element (heating coil) and a coil (inspection coil or initialization coil) for generating a magnetic field in a direction substantially the same as or substantially orthogonal to the magnetic field detection direction of the magnetoresistive element. Therefore, the cost of the magnetic sensor can be reduced by shortening the manufacturing process and the number of manufacturing masks. Also, by energizing the coil, it is possible to measure the temperature-dependent characteristics of the magnetic sensor and perform all or part of the inspection of the magnetic sensor, or all or part of the initialization of the magnetic sensor at the same time. Therefore, the manufacturing (inspection) time can be shortened and the manufacturing cost of the magnetic sensor can be reduced.

Further, another magnetic sensor disclosed in the present specification includes a plurality of magnetoresistive elements formed on the upper surface of a layer stacked on a substrate, and one heating element that generates heat when energized, A magnetic sensor that generates an output value according to an external magnetic field applied to the magnetoresistive effect element based on the resistance values of the plurality of magnetoresistive effect elements, wherein the heating element has a temperature of the plurality of magnetoresistive effect elements It is characterized by being arranged and configured to be substantially equal to each other and to have a non-uniform temperature on the upper surface of the layer on which the plurality of magnetoresistive elements are formed.

  Even with this configuration, the plurality of magnetoresistive elements are heated to substantially the same temperature (different from the substrate temperature) without being heated until the entire magnetic sensor including the substrate reaches the same temperature. The time required for heating and cooling the magnetoresistive effect element can be shortened, and the temperature-dependent characteristics of the magnetoresistive effect element can be measured within a period in which the same geomagnetism is applied.

  In this case, the heat generating element and the plurality of magnetoresistive effect elements are configured such that the amount of heat transferred from the heat generating element to any one of the plurality of magnetoresistive effect elements is the same. It can be configured to be substantially the same as the amount of heat transferred to the other one of the resistance effect elements.

  In addition, the heating element and the plurality of magnetoresistive effect elements have a relative positional relationship between the heating element and any one of the plurality of magnetoresistive effect elements. It can be arranged so as to be substantially the same as the relative positional relationship with the other one of the effect elements.

  The plurality of magnetoresistive elements are arranged in four islands on the top surface of the layer stacked on the substrate in an island shape, and substantially central portions of adjacent islands are connected by a straight line. When rotated by 90 ° in the plane parallel to the upper surface of the same layer around the center of gravity of the quadrangle, any one island is adjacent to the other in the direction of rotation before the 90 ° rotation. It is preferable that it is formed so as to substantially coincide with the position of the island.

  In the magnetic sensor having any of the above characteristics, the temperatures of the plurality of magnetoresistive elements are substantially equal to each other, and the temperature of the upper surface of the layer on which the plurality of magnetoresistive elements are formed is not uniform. Then, a temperature detection unit that outputs a temperature having a certain correlation with the temperature of at least one of the plurality of magnetoresistive elements as a detection temperature can be provided.

  Since the magnetoresistive elements are heated to substantially the same temperature by the heat generated by the heating element, if the temperature detector has a certain correlation with the temperature of one magnetoresistive element, substantially all The temperature of the magnetoresistive effect element having the same configuration can be detected. Therefore, according to the above configuration, since it is not necessary to increase the number of temperature detection units, the cost of the magnetic sensor can be reduced.

  Further, the magnetic sensor having such a temperature detection unit, wherein the plurality of magnetoresistive elements have the same magnetic field detection direction among the same elements so as to generate an output value corresponding to the external magnetic field. Are connected to each other to form a bridge circuit, and further, a memory, “the first temperature of the magnetoresistive effect element determined based on the temperature detected by the temperature detection unit, and the magnetic sensor at the first temperature The data at the second temperature and the second temperature of the magnetoresistive effect element different from the first temperature determined based on the temperature detected by the temperature detecting unit and the data consisting of the first output value as the output value. The first output value and the second output value with respect to the difference between the first temperature and the second temperature, which are determined on the basis of the data consisting of the second output value that is the output value of the magnetic sensor. The value according to the ratio of the difference with A temperature-dependent characteristic writing means for writing the memory, it is preferable to comprise a.

  The temperature-dependent characteristics of a magnetic sensor in which a plurality of magnetoresistive elements are connected so as to form a bridge circuit (full bridge circuit) is such that the output changes in proportion to the temperature change of the magnetoresistive element. . Therefore, a value corresponding to the above “ratio” (that is, the change in the output value of the magnetic sensor with respect to the temperature change of the magnetoresistive element) (the same ratio itself or the reciprocal of the same ratio may be stored) in the memory. For example, after the magnetic sensor is mounted on another electronic device, the electronic device reads out a value corresponding to the same “ratio” from the memory, thereby obtaining data on the temperature dependence characteristics of the mounted magnetic sensor. Therefore, it is possible to compensate for the temperature-dependent characteristics of the magnetic sensor using the data.

  In other words, only by storing a value corresponding to the “ratio” in the memory of each magnetic sensor, the data about the temperature-dependent characteristics of each magnetic sensor can be held in each magnetic sensor. Therefore, compared with the case where the first temperature, the first output value, the second temperature, and the second output value are stored in the memory, the capacity of the memory for storing the data on the temperature dependence characteristics of the magnetic sensor is reduced. Thus, the cost of the magnetic sensor can be reduced.

In addition, according to the technique disclosed in this specification , a temperature having a certain correlation with the temperature of the magnetoresistive effect element, the first memory, and the magnetoresistive effect element whose resistance value changes according to an external magnetic field is detected temperature. A magnetic sensor for generating an output value in accordance with the external magnetic field based on the resistance value of the magnetoresistive element, and a permanent magnet component. A temperature-dependent characteristic compensation method for a magnetic sensor, which is applied to an electronic device comprising a case and a second memory, the magnetic sensor, the permanent magnet component, and the second memory being housed in the case. Before storing the magnetic sensor in the case, the temperature of the magnetoresistive element is acquired as a first temperature based on the temperature detected by the temperature detector, and the magnet at the first temperature is acquired. The sensor output value is acquired as the first output value, and after changing the energization state of the heating element, the temperature of the magnetoresistive effect element is acquired as the second temperature based on the temperature detected by the temperature detection unit. The output value of the magnetic sensor at the second temperature is acquired as a second output value, and the output value according to the ratio of the difference between the first output value and the second output value with respect to the temperature difference between the first temperature and the second temperature. The value is stored in the first memory, and after the magnetic sensor is accommodated in the case together with the permanent magnet component, the offset value of the output value of the magnetic sensor and the detected temperature of the temperature detection unit are used as a reference in the second memory. Based on the value according to the ratio stored in the first memory, the reference data stored in the second memory, and the detected temperature of the temperature detector, Magnetic field Temperature dependence compensation method of a magnetic sensor for correcting the output value of the sensor is provided.

  According to this, at the stage of the magnetic sensor alone, a value corresponding to the “ratio”, which is data representing the temperature dependence characteristics of the magnetic sensor, is stored in the first memory. Then, after the magnetic sensor is housed in the case together with the permanent magnet component and the second memory, the offset value of the output value of the magnetic sensor and the temperature detected by the temperature detection unit when the offset value is acquired are the second. Stored in the memory, and thereafter, the value according to the difference between the actual temperature detected by the temperature detection unit and the temperature stored in the second memory, the “ratio” stored in the first memory, The actual output value of the magnetic sensor is corrected based on the offset value stored in the second memory.

  This method will be described using a specific example. By multiplying the difference between the actual temperature detected by the temperature detection unit and the temperature stored in the second memory by the “ratio” stored in the first memory. The amount of change of the offset value accompanying the temperature change of the magnetic sensor is obtained, and by adding the offset value stored in the second memory to this, the offset value after the temperature change is obtained, and the actual output value of the magnetic sensor And the offset value after this temperature change is used as a value according to the external magnetic field to be detected.

Thus, according to the temperature-dependent characteristic compensating method, since stored in the first memory is measured when the "ratio" value corresponding to the magnetic sensor is a single state, the the magnetic sensor itself Data representing temperature dependent characteristics of the magnetic sensor can be held. In addition, since the offset value and the temperature detected by the temperature detection unit are stored in the second memory after the magnetic sensor is mounted together with the permanent magnet parts in the case of the electronic device, the same value as the offset value of the magnetic sensor itself is stored in the first memory. It is not necessary to store the temperature detected by the temperature detection unit when the offset value is obtained, and the storage capacity of the first memory can be reduced to reduce the cost of the magnetic sensor. Also, the offset of the magnetic sensor based on the offset (reference deviation) of the magnetic sensor alone based on the individual difference (resistance value variation) of the magnetoresistive effect element and the offset (reference deviation) based on the leakage magnetic field from the permanent magnet component. Since the value is obtained at a time after being mounted in the case, it is not necessary to obtain the offset value twice. As described above, according to the above technique , the temperature dependence characteristic of the magnetic sensor can be compensated by a simple method.

Magnetic sensor provided by the present invention, the physical quantity based on the resistance value of a single substrate, a plurality of magnetoresistive elements, the wiring section and the plurality of magnetoresistive elements bridging connection the plurality of magnetoresistive elements A magnetic sensor including a control circuit unit that generates an output signal to be output to the outside by processing the same physical quantity and acquiring a plurality of layers stacked on the substrate. The magnetoresistive effect element is formed on an upper surface of one of the plurality of layers, the wiring portion and the control circuit portion are formed in the substrate and the plurality of layers, and the magnetoresistive effect element and the The wiring part and the control circuit part are magnetic sensors connected to each other by a connection part made of a conductive material extending in a direction intersecting the layer surface of the same layer in the plurality of layers.

  According to this, the magnetoresistive effect element, the wiring portion, and the control circuit portion are crossed with each other by a connection portion made of a conductive material extending in a direction intersecting the layer surface of the same layer in the plurality of layers. When a chip with a magnetoresistive effect element and a chip with a control circuit unit, etc. are made as separate chips, the output of the magnetic sensor can be obtained without using connection wires required between them. A single chip magnetic sensor capable of generating a signal is provided.

  According to another aspect of the magnetic sensor provided by the present invention, a substrate, a plurality of magnetoresistive elements disposed on the substrate, and the plurality of magnetoresistive elements disposed on the substrate are provided. A wiring unit to be connected and an output that is disposed on the substrate and outputs a physical quantity based on resistance values of the plurality of magnetoresistive elements through the wiring unit and outputs the physical quantity to the outside by processing the physical quantity In the magnetic sensor including a control circuit unit for generating a signal, the plurality of magnetoresistive elements are arranged at a peripheral portion of the substrate in a plan view, and the wiring unit substantially forms a closed curve in the plan view. The control circuit unit is arranged substantially inside the closed curve in a plan view.

  According to this, the control circuit unit for generating the output signal based on the resistance change of the magnetoresistive effect element or acquiring the temperature characteristic data of the magnetoresistive effect element is compactly arranged in the central portion of the substrate in a plan view. It can be arranged. Therefore, since the wiring length of the control circuit section is shortened, it is difficult for external noise to be superimposed on the wiring. As a result, a highly reliable magnetic sensor that is hardly affected by external noise is provided.

Another aspect of the magnetic sensor provided by the present invention is provided with a single substrate, a plurality look including the element group comprising a pair of magneto-resistive elements magnetization direction of the pinned layer are identical to each other, wherein In the magnetic sensor in which the magnetization directions of the pinned layer of at least two element groups of the element groups are orthogonal to each other , each of the plurality of element groups has the magnetization direction of the pinned layer in plan view. The pair of magnetoresistive elements are arranged on the same substrate so as to be substantially parallel to the direction in which the distance from the center of gravity (center) increases.
The magnetic sensor according to this aspect includes a single substrate and includes a plurality of element groups each including a pair of magnetoresistive effect elements having the same magnetization direction of the pinned layer, and includes at least two of the element groups. In the magnetic sensor in which the “direction of magnetization of the free layer of the magnetoresistive effect element when no external magnetic field is applied” of the element group is orthogonal to each other, each of the plurality of element groups is not applied with the external magnetic field So that the direction of magnetization of the free layer is substantially perpendicular to the direction in which the distance from the center of gravity of the substrate increases in plan view, and the pair of magnetoresistive elements are adjacent to each other. It is also a magnetic sensor disposed on the substrate.

  When the magnetization direction of the pinned layer is fixed, it is necessary to continuously apply a magnetic field having a stable direction and magnitude to the magnetoresistive element. At this time, at two adjacent points on the same magnetic field line, the magnetic fields have substantially the same magnitude in substantially the same direction. Further, in the magnetic sensor, for the purpose of improving the temperature characteristics and the like of the magnetic sensor, the magnetization direction of the pinned layer is the same (that is, the magnetic field detection direction is the same). In many cases, a plurality of element groups are provided and these magnetoresistive elements are bridge-connected.

  Therefore, as in the above configuration, the direction of magnetization of the pinned layer is substantially parallel to the direction in which the distance from the center of gravity (center) of the substrate increases in plan view, and the pair of magnetoresistive resistors If the magnetic sensor is arranged on the upper part of the substrate so that the effect elements are adjacent in the same direction, by applying a magnetic field from the center of gravity (center) to the periphery of the substrate, the same size in the same direction The magnetization of the pinned layer of the magnetoresistive effect element can be fixed by a magnetic field having As a result, the magnetization direction of the pinned layer can be easily and reliably performed in the same direction.

(First embodiment)
Hereinafter, embodiments of a magnetic sensor according to the present invention will be described in order with reference to the drawings. 1 is a schematic plan view of the magnetic sensor 10 according to the first embodiment, FIG. 2 is a partial schematic plan view of the magnetic sensor 10 showing an electrical connection state of the magnetic sensor 10, and FIG. It is the partial schematic sectional drawing which cut | disconnected the magnetic sensor 10 by the predetermined surface orthogonal to the surface of each layer mentioned later which comprises the shown magnetic sensor 10. FIG.

The magnetic sensor 10 is substantially a square (or rectangular), Si ₃ having a small thickness in the Z axis direction perpendicular to the X-axis and Y-axis having sides along the X-axis and Y-axis orthogonal to each other A substrate 10a formed of N ₄ / Si, SiO ₂ / Si, quartz glass, or the like, a layer INS1 and layers S1 to S3 having the same shape as the substrate 10a in a plan view laminated on the substrate 10a, A total of eight GMR elements 11 to 18 that are magnetoresistive elements formed on the layer S3 (upper surface) and a passivation film PL formed on the uppermost surface are included.

  As shown in FIG. 1, the magnetic sensor 10 includes a bridge wiring portion (connecting wire portion) 19 for forming two full bridge circuits by bridge-connecting the GMR elements 11 to 14 and the GMR elements 15 to 18 respectively. Heating coils 21 to 24 as heating elements for heating the GMR elements 11 to 18, a control circuit unit (LSI) 31, a temperature detection unit 32, inspection coils 33a to 33d, and Au wires Pads 34a to 34h for bonding the magnetic sensor 10 to an external device through the Au wire by bonding to the upper surface are provided.

  The GMR element 11 is referred to as a first X-axis GMR element 11, and as shown in FIG. 1, is formed in the approximate center of the side along the Y-axis direction of the substrate 10a and in the vicinity of the end in the X-axis negative direction. Yes. The GMR element 12 is referred to as a second X-axis GMR element 12 and is slightly centrally located on the side of the substrate 10a along the Y-axis direction and slightly closer to the X-axis negative direction end than the first X-axis GMR element 11. The first X-axis GMR element 11 is disposed in proximity to the first X-axis GMR element 11 at a position in the axial positive direction.

  The GMR element 13 is referred to as a third X-axis GMR element 13, and is formed at a substantially central portion of the side along the Y-axis direction of the substrate 10a and in the vicinity of the end portion in the X-axis positive direction. The GMR element 14 is referred to as a fourth X-axis GMR element 14 and is slightly centrally located on the side of the substrate 10a along the Y-axis direction and slightly closer to the X-axis positive direction end than the third X-axis GMR element 13. It is arranged close to the third X-axis GMR element 13 at a position in the negative axis direction (close proximity arrangement).

  The GMR element 15 is referred to as a first Y-axis GMR element 15 and is formed at a substantially central portion of a side along the X-axis direction of the substrate 10a and in the vicinity of an end portion in the Y-axis positive direction. The GMR element 16 is referred to as a second Y-axis GMR element 16, and is slightly in the middle of the side along the X-axis direction of the substrate 10 a and slightly closer to the Y-axis positive direction end than the first Y-axis GMR element 15. It is arranged close to the first Y-axis GMR element 15 at a position in the negative axis direction (close arrangement).

  The GMR element 17 is referred to as a third Y-axis GMR element 17 and is formed at a substantially central portion of the side along the X-axis direction of the substrate 10a and in the vicinity of the end portion in the Y-axis negative direction. The GMR element 18 is referred to as a fourth Y-axis GMR element 18, which is approximately the center of the side along the X-axis direction of the substrate 10 a and slightly closer to the Y-axis negative direction end than the third Y-axis GMR element 17. It is arranged close to the third Y-axis GMR element 17 at a position in the axial positive direction (close arrangement).

  The spin valve films constituting each of the GMR elements 11 to 18 are a free layer (free layer), a conductive spacer layer, a pinned layer (layered) formed in order on the upper surface of the layer S3 on the substrate 10a. A fixed magnetic layer) and a capping layer. The magnetization direction of the free layer is easily changed according to the change of the external magnetic field. The pinned layer includes a pinning layer and a pinned layer, and the magnetization direction of the pinned layer is fixed by the pinning layer, and the magnetization direction does not change with respect to an external magnetic field except in special cases.

  As a result, each of the GMR elements 11 to 18 exhibits a resistance value corresponding to an angle formed by the magnetization direction of the pinned layer and the magnetization direction of the free layer. That is, each of the GMR elements 11 to 18 has the same external frequency in the range of −Hc to + Hc with respect to an external magnetic field that changes along the magnetization direction of the pinned layer, as indicated by a solid line in the graph of FIG. It exhibits a resistance value that varies approximately in proportion to the magnetic field, and is substantially constant for an external magnetic field that varies along a direction orthogonal to the magnetization direction of the pinned layer, as indicated by a broken line in the graph of FIG. The resistance value is shown. In other words, each of the GMR elements 11 to 18 has the magnetization direction of the pinned layer as its magnetic field detection direction.

  The direction of pinned magnetization of each pinned layer of the GMR element 11 and the GMR element 12 is the negative X-axis direction. In other words, the first X-axis GMR element 11 and the second X-axis GMR element 12 are a plurality for detecting the magnitude of the magnetic field in the same direction (in this case, the X-axis direction) (that is, the magnetic field detection directions are the same). The magnetoresistive effect elements are arranged in an island shape on the upper surface of the layer S3 laminated on the substrate 10a to form one element group Gr1.

  The pinned magnetization direction of each pinned layer of the GMR element 13 and the GMR element 14 is the positive direction of the X axis. That is, the third X-axis GMR element 13 and the fourth X-axis GMR element 14 include a plurality of magnetoresistive elements for detecting the magnitude of the magnetic field in the same direction (in this case, the X-axis direction) with respect to the substrate 10a. Thus, another element group Gr2 is formed which is arranged in an island shape on the upper surface of the stacked layer S3.

  The pinned magnetization directions of the pinned layers of the GMR element 15 and the GMR element 16 are the Y axis positive direction. That is, the first Y-axis GMR element 15 and the second Y-axis GMR element 16 include a plurality of magnetoresistive elements for detecting the magnitude of the magnetic field in the same direction (in this case, the Y-axis direction) with respect to the substrate 10a. Thus, another element group Gr3 is formed which is arranged in an island shape on the upper surface of the stacked layer S3.

  The pinned magnetization direction of the pinned layers of the GMR element 17 and the GMR element 18 is the negative Y-axis direction. That is, the third Y-axis GMR element 17 and the fourth Y-axis GMR element 18 include a plurality of magnetoresistive elements for detecting the magnitude of the magnetic field in the same direction (in this case, the Y-axis direction) with respect to the substrate 10a. Thus, another element group Gr4 is formed which is arranged in an island shape on the stacked layer S3.

  Thus, the GMR elements 11 to 18 form four element groups (islands) Gr1 to Gr4 in which two magnetoresistive effect elements having the same magnetic field detection direction are arranged in close proximity to each other. Yes. These element groups Gr1 to Gr4 are disposed on the outer side of the substantially central portion of each side of a square having a side along the X axis or the Y axis in a plan view (a square formed by the bridge wiring portion 19 in a plan view). When the element group is rotated 90 ° around the center of gravity of the square (the center of the square, that is, the intersection of the diagonals of the square), the position of the element group matches the position of the other element group adjacent to the square before the rotation. Is formed. In other words, the plurality of GMR elements 11 to 18 are arranged in four islands on the upper surface of the layer S3 stacked on the substrate 10a in an island shape, and the substantially central portions of the islands adjacent to each other. When rotated by 90 ° in a plane parallel to the top surface of the layer S3 about the center of gravity GP of the quadrilateral connected by a straight line, any one island is adjacent in the same rotation direction before the 90 ° rotation It is formed so as to substantially coincide with the position of other islands. That is, for example, a straight line connecting substantially central parts of the element groups Gr2 and Gr3, a straight line connecting substantially central parts of the element groups Gr3 and Gr1, a straight line connecting substantially central parts of the element groups Gr1 and Gr4, and When four straight lines (line segments) are obtained, such as straight lines connecting the substantially central portions of the element groups Gr4 and Gr2, and rotated by 90 ° about the center of gravity of the quadrangle obtained by these line segments, for example, The element group Gr2 coincides with the position of the element group Gr3 and the element group Gr3 coincides with the position of the element group adjacent to each other, such as the position of the element group Gr1.

  In the example shown in FIGS. 1 to 3, the two GMR elements constituting one island (one element group) are from the center of the substrate 10a (center of gravity, the center of gravity coincides with the center of gravity GP). It arrange | positions so that it may adjoin to the direction which faces one side (periphery) of the board | substrate 10a. That is, each of the plurality of element groups Gr1 to Gr4 including a pair of magnetoresistive elements having the same magnetic field detection direction has a magnetization direction of the pinned layer of the magnetoresistive element from the center of gravity of the substrate 10a in plan view. The pair of magnetoresistive elements are arranged on the upper part of the substrate 10a so as to be substantially parallel to the direction in which the distance increases and so that the pair of magnetoresistive elements are adjacent in the same direction. However, as shown in FIG. 5, the pair of magnetoresistive elements may be arranged so as to be adjacent in a direction along one side of the substrate 10 a. However, according to the former arrangement, since the GMR element is closer to the center of each (square) side of the substrate 10a than the latter arrangement, the characteristics between the elements are likely to be uniform. Further, the former is easier to apply a magnetic field having the same magnitude in the same direction to the pair of magnetoresistive elements than the latter.

  As illustrated in FIG. 6, which is an enlarged plan view of the vicinity of the GMR elements 11 and 12, the GMR elements 11 to 14 are connected to each wiring of the bridge wiring portion 19, and an equivalent circuit diagram is provided via the bridge wiring portion 19. As shown in FIG. 7, a bridge circuit is configured (with full bridge connection), and an X-axis magnetic sensor having the X-axis direction as the magnetic field detection direction is configured. Note that. In FIG. 7, arrows attached to the GMR elements 11 to 14 indicate the magnetization directions of the pinned layers of the GMR elements 11 to 14.

  More specifically, the X-axis magnetic sensor includes a coupling point Va between the first X-axis GMR element 11 and the fourth X-axis GMR element 14, and a coupling point between the third X-axis GMR element 13 and the second X-axis GMR element 12. A constant potential difference is applied between Vb, the coupling point Vc between the first X-axis GMR element 11 and the third X-axis GMR element 13, and the coupling point Vd between the second X-axis GMR element 12 and the fourth X-axis GMR element 14. (Vc−Vd) is taken out as a sensor output value Vxout. As a result, the output voltage (physical quantity represented by voltage) of the X-axis magnetic sensor is -Hc to + Hc with respect to an external magnetic field whose magnitude varies along the X-axis as shown by the solid line in FIG. In this range, it changes approximately in proportion to the magnitude of the external magnetic field, and is substantially “0” for an external magnetic field whose magnitude changes along the Y axis, as indicated by the broken line in FIG. Is a constant value.

  Similarly to the GMR elements 11 to 14, the GMR elements 15 to 18 are connected to the respective wirings of the bridge wiring portion 19 to form a bridge circuit (a full bridge connection), and the Y axis direction is a magnetic field detection direction. An axial magnetic sensor is configured. In other words, this Y-axis magnetic sensor has an output voltage (in terms of voltage) that changes approximately in proportion to the magnitude of the external magnetic field in the range of −Hc to + Hc with respect to an external magnetic field whose magnitude changes along the Y-axis. The physical quantity is expressed as Vyout, and an output voltage of substantially “0” is shown for an external magnetic field whose magnitude changes along the X axis.

As shown in FIG. 1, the bridge wiring portion 19 is formed in a substantially square outer peripheral portion having sides along the X axis and the Y axis inside the GMR elements 11 to 18 in a plan view, and is substantially a closed curve ( A straight portion is included). The bridge wiring portion 19 is formed in the layer S3 below the GMR elements 11 to 18, as will be described in detail later.
As shown in FIGS. 1 and 3, the heating coils 21 to 24 are respectively embedded immediately below the element groups Gr1 to Gr4 (on the Z-axis negative direction side) and in layers S3 functioning as wiring layers. Yes. The heating coils 21 to 24 have substantially the same shape, and the relative positional relationship with the corresponding element groups Gr1 to Gr4 is also substantially the same. Therefore, in the following, the heating coil 21 will be described in detail.

  The heating coil 21 is made of, for example, a thin film of aluminum, and is a heating element that generates heat when energized to heat the first and second GMR elements 11 and 12 (element group Gr1), and is present in a portion immediately below the element group Gr1. It is formed in the layer S3 so as to face the lower surfaces of the magnetoresistive elements 11 and 12 (disposed close to the element group Gr1). That is, as can be understood from FIG. 3, the heating coil 21 includes GMR elements 11 to 18 formed on the upper surface of the insulating layer INS1 and the layers S1 to S3 that function as the wiring layers sequentially stacked on the substrate 10a. Embedded in the layer S3 (the uppermost layer S3 of the layers S1 to S3 functioning as a wiring layer). Here, the layer functioning as a wiring layer refers to a wiring, an interlayer insulating film between the wirings, and a contact hole (including a via hole) that connects the wirings, as will be described later.

  Further, as shown in FIG. 6, the heating coil 21 is a so-called double spiral coil, and its outer shape in plan view is substantially rectangular, and the Y-axis direction length of the rectangle is the magnetoresistive effect element 11 ( 12) is approximately twice the length in the longitudinal direction, and the length in the X-axis direction is approximately 5 times the length in the width direction (direction perpendicular to the longitudinal direction) of the magnetoresistive element 11 (12). It consists of conducting wires forming a spiral (that is, a first conducting wire 21-1 having a vortex center P1 and a second conducting wire 21-2 having a vortex center P2).

  The first and second X-axis GMR elements 11 and 12 are arranged between the pair of vortex centers P1 and P2 in a plan view. Further, in the same plan view, the first conductors 21-1 and the first conductors 21-1 that overlap with the first and second X-axis GMR elements 11 and 12 (that is, the parts that pass directly under the first and second X-axis GMR elements 11 and 12) The portion of the second conducting wire 21-2 has a linear shape along the X-axis direction parallel to each other. A current in the same direction flows through each of the conductors in the linear portion, and a magnetic field in the Y-axis direction is generated for the first and second X-axis GMR elements 11 and 12. That is, the heating coil 21 is in the longitudinal direction of the first and second X-axis GMR elements 11 and 12, and the direction of magnetization in the design of the free layer when no external magnetic field is applied (pinned layer fixing). A magnetic field having a direction perpendicular to the direction of magnetization).

  As described above, the magnetic sensor 10 according to the first embodiment is a magnetic sensor including a GMR element (a magnetoresistive effect element including a free layer and a pinned layer), and is a free layer in a state where an external magnetic field is not applied. Is provided below (in close proximity to) the free layer in order to stabilize (initialize) the direction of magnetization, and energization under predetermined conditions (for example, before the start of magnetic detection). Is a magnetic sensor including heating coils 21 to 24 that can generate a magnetic field (initialization magnetic field) in a predetermined direction (direction perpendicular to the pinned magnetization direction of the pinned layer) in the free layer. The heating coils 21 to 24 are magnetic sensors configured to heat the GMR element (group) immediately above each of them by energizing a predetermined pattern under a predetermined condition.

  As shown in FIG. 1, the control circuit unit 31 is arranged inside the bridge wiring unit 19 in a plan view (inside a substantially closed curve formed by the wiring unit 19 in a plan view, that is, in the center of the substrate 10 a). It is formed so as to form a substantially square shape having sides along the axis and the Y axis. As shown in FIG. 3, the control circuit unit 31 is formed in the layers INS1 and S1 to S3 below the GMR elements 11 to 18. The control circuit unit 31 includes an AD conversion unit (ADC), a write-once memory that can write data once and can always read it (also referred to as “first memory” for convenience), and an analog circuit unit. LSI. The control circuit unit 31 obtains output values (physical quantities as voltages based on resistance values) of the X-axis magnetic sensor and the Y-axis magnetic sensor, generates an output signal by processing such as AD conversion, and supplies the output signals to the heating coils 21 to 24. Functions such as energization, acquisition of temperature detected by the temperature detector 32, acquisition of temperature compensation data, and storage (writing) of the data in the first memory are achieved.

  Thus, the wiring length of the control circuit unit 31 can be shortened by disposing the control circuit unit 31 in the center of the substrate 10a. Therefore, since the resistance of the circuit is small and the circuit itself is miniaturized, it is difficult to be affected by noise, and variation in resistance (variation between products) included in the circuit can be reduced.

  As the write-once memory, a fuse cutting type 24-bit memory can be used. However, instead of such a memory, a memory (nonvolatile memory) such as an EEPROM or a flash memory that can write data and can retain data even when the power supply is cut off may be adopted. it can.

  The temperature detection unit 32 is configured by a known bandgap reference circuit that detects a temperature based on the temperature characteristics of a built-in transistor. The temperature detection unit 32 is inside the bridge wiring unit 19 in a plan view, and includes a control circuit unit 31. It is formed at the corner. The temperature detector 32 is formed in the wiring layer S1 at a position closer to the GMR elements 17 and 18 (element group Gr4) than the GMR elements 11 to 16, and is always constant with the temperature of the GMR element 18 (element group Gr4). The temperature (detection temperature) with the correlation of is output. As will be described later, since the magnetoresistive effect elements 11 to 18 are heated to the same temperature, the temperature of the other magnetoresistive effect elements 11 to 17 is detected by detecting the temperature of the magnetoresistive effect element 18. You can also know.

  Thus, by arranging the temperature detection unit 32 in the vicinity of the element group Gr4 and inside the bridge wiring unit 19, the temperature detection unit 32 can detect the temperature of the GMR element 18 with high accuracy. Further, since the temperature detection unit 32 is connected to the control circuit unit 31 without straddling the bridge wiring unit 19, the wiring length between the temperature detection unit 32 and the control circuit unit 31 can be shortened.

  As illustrated in FIG. 3, the inspection coils 33 a to 33 d are formed immediately below the element groups Gr1 to Gr4 and in the wiring layer S <b> 1. The inspection coils 33a to 33d apply a magnetic field in a magnetic field detection direction (magnetic field in the direction of magnetization of the pinned layer) of each magnetoresistive effect element positioned immediately above by energization to each of the magnetoresistive effect elements. .

  Here, the layer structure of the magnetic sensor 10 will be described. As shown in FIG. 3, the upper portion of the substrate 10a is divided into an element isolation region 10a1 and other activation regions 10a2. The element isolation region 10a1 is formed on the upper surface of the substrate 10a as a field insulating film ins by the LOCOS method or the STI method. The LOCOS method is a well-known technique for insulating and isolating elements from each other with a thermal oxide film. The STI method is called shallow trench element isolation, and is a well-known technique for insulating and isolating elements from each other by embedding an oxide film in a shallow trench.

  An insulating layer INS1 is formed immediately above the substrate 10a and on the upper surface of the insulating layer ins. A circuit element such as a transistor Tr is formed in the element activation region 10a2 in the insulating layer INS1. Elements such as a resistor R, a fuse, and a capacitor are formed in the element isolation region 10a1 in the insulating layer INS1. Further, in the insulating layer INS1, a plurality of contact holes C1 (connection portions, vertical connection portions) for electrically connecting circuit elements such as the transistor Tr and wirings formed in the upper layer S1 are provided. Is formed so as to be orthogonal to the layer surfaces of the layers S1 to S3 (so as to intersect the layer surfaces of the layers S1 to S3). The contact hole C1 is filled with a conductive material.

  A layer S1 functioning as a wiring layer is formed on the insulating layer INS1. The layer S1 includes a wiring W1 made of a conductive film, inspection coils 33a to 33d, an interlayer insulating film IL1, a temperature detection unit 32, and the like. Further, in the interlayer insulating film IL1, a plurality of via holes V1 (connection portions, vertical connection portions) for electrical connection with wirings and the like formed in the upper layer S2 are orthogonal to the layer surfaces of the layers S1 to S3. (So as to intersect with the layer surfaces of the layers S1 to S3). The via hole V1 is filled with a conductive material.

  Similarly, a layer S2 functioning as a wiring layer is formed on the layer S1. The layer S2 includes a wiring W2 made of a conductive film and an interlayer insulating film IL2. Further, in the interlayer insulating film IL2, a plurality of via holes V2 (connection portions, longitudinal connection portions) for electrical connection with wirings and the like formed in the upper layer S3 are orthogonal to the layer surfaces of the layers S1 to S3. (So as to intersect with the layer surfaces of the layers S1 to S3). The via hole V2 is filled with a conductive material.

  Similarly, a layer S3 functioning as a wiring layer is formed on the layer S2. The layer S3 includes a wiring W3 made of a conductive film, a bridge wiring portion 19, a heating coil 21 (22 to 24), and an interlayer insulating film IL3. The interlayer insulating film IL3 has a plurality of via holes V3 (connection portions, vertical connection portions) for making electrical connection with the GMR elements 11 to 18 formed on the upper surface of the layer S3. So as to be orthogonal to each other (crossing the layer surfaces of the layers S1 to S3). The via hole V3 is filled with a conductive material. The interlayer insulating film IL3 may be a passivation film including a nitride film different from a passivation film PL described later in order to protect the control circuit unit 31. The upper surface of the interlayer insulating film IL3 is preferably flattened so that the characteristics of the GMR elements 11 to 18 are maintained well. The contact hole C1 and the via holes V1 to V3 are connection portions that connect the GMR elements 11 to 18, the bridge wiring portion 19 that is a wiring portion, the control circuit portion 31, and the like to each other, and a plurality of layers INS1, S1. It can be said that it is a connection part which consists of an electroconductive substance extended in the direction which cross | intersects the layer surface of these layers in -S3.

  The pad region PD is a region other than the portion where the GMR elements 11 to 18 are formed, the bridge wiring portion 19 and the control circuit portion 31, and is provided at the corner of the magnetic sensor 10 in plan view (FIG. 1). See). The upper surface of the pad region PD constitutes the above-described pads 34a to 34h. The pads 34a to 34h may be formed only on the uppermost layer S3, but receive an impact when bonding Au wires. Therefore, in this example, the substantially square pad portion in plan view is formed across a plurality of layers S1 to S3.

  The passivation film PL is formed so as to cover the upper surface of the layer S3 and the GMR elements 11-18. After the passivation film PL is formed so as to cover the whole, portions corresponding to the pads 34a to 34h are removed. As a result, the pads 34a to 34h are exposed to be bonded to the Au wire.

  Such a magnetic sensor 10 is accommodated and mounted in a mobile phone 40 as a portable electronic device whose schematic external front view is shown in FIG. The mobile phone 40 is a substantially rectangular shape having sides extending along the x-axis and the y-axis that are orthogonal to each other when viewed from the front, and has a thickness (z) in the z-axis direction orthogonal to the x-axis and the y-axis. The antenna unit 42 disposed on the upper side surface of the case 41, the speaker unit 43 disposed on the uppermost front side of the case 41, and disposed on the front side of the case 41 below the speaker unit 43 to display characters and figures. Liquid crystal display unit 44, an operation unit (operation signal input means) 45 disposed on the front side of the case 41 below the liquid crystal display unit 44 and including a switch for inputting a telephone number or other instruction signal. It is configured to be communicable with the magnetic sensor 10 and the display unit 44 via the microphone unit 46 disposed at the lowermost part on the front surface side, and the bus, and with a RAM and a backup memory (E May even PROM, when the main power is turned off, a memory for holding data, and a microcomputer 47 with a built-in convenience "second memory" also to referred.).

  Some or all of the antenna unit 42, the speaker unit 43, the liquid crystal display unit 44, the operation unit 45, and the microphone unit 46 include a permanent magnet component (leakage magnetic field generating component) as its component. The magnetic sensor 10 is accommodated and fixed in the case so that the X, Y, and Z axes thereof coincide with the x, y, and z axes of the case 41, respectively.

  Next, a temperature dependent characteristic compensation method for the magnetic sensor 10 configured as described above will be described. A magnetoresistive effect element such as a GMR element has a temperature-dependent characteristic in which, for example, resistance increases as the temperature rises due to its material characteristics, and the temperature-dependent characteristic varies from element to element. Therefore, the magnetic sensor 10 (each of the X-axis magnetic sensor and the Y-axis magnetic sensor), which is a full bridge circuit of four GMR elements, also has a temperature-dependent characteristic that its output changes as the temperature changes. However, the temperature dependence characteristics include that the output of the magnetic sensor 10 increases with the temperature rise of the GMR element and the temperature rise of the GMR element due to the temperature dependence characteristic of each GMR element constituting the magnetic sensor 10. There are things that decrease.

  FIG. 10 and FIG. 11 are graphs showing examples of temperature-dependent characteristics of such a magnetic sensor, respectively. Here, an example is shown in which the X-axis magnetic sensor has a negative temperature-dependent characteristic and the Y-axis magnetic sensor has a positive temperature-dependent characteristic, and the solid line indicates the X component of the external magnetic field (for example, geomagnetism at a predetermined time at a predetermined time). The output values Vxout and Vyout of the magnetic sensors when the Y components are HX0 and HY0, respectively, and the alternate long and short dash lines are external magnetic fields excluding the influence of geomagnetism (for example, leakage magnetic fields from the permanent magnet parts of the mobile phone 40). The output values Vxout and Vyout of each magnetic sensor in the case of HX1 and HY1 are shown.

  As understood from FIGS. 10 and 11, the output values Vxout and Vyout of the magnetic sensor 10 change approximately in proportion to the temperature of the GMR element with respect to the same magnetic field. Therefore, in the present embodiment, temperature dependent characteristics are compensated under the assumption that the output values Vxout and Vyout of each magnetic sensor change in proportion to the GMR element temperature.

  First, when a predetermined condition for acquiring temperature-dependent characteristic compensation data is satisfied, for example, when an instruction signal is input from the outside, the control circuit unit 31 corresponds to the temperature of the GMR element 18 at that time. Is detected as the first temperature T1s. In this case, since the entire magnetic sensor 10 has a uniform temperature (room temperature), the detection temperature T1s of the temperature detection unit 32 is equal to the temperature T1 of the GMR element 18. At the same time, the control circuit unit 31 outputs the X-axis magnetic sensor output value X1 (X-axis magnetic sensor first output value X1) and the Y-axis magnetic sensor output value Y1 (Y-axis magnetic sensor first output value Y1) at that time. And get. Next, the control circuit unit 31 energizes the heating coils 21 to 24 with a current of 100 mA in order of 100 ms. Thereby, the element groups Gr1 to Gr4 are heated to substantially the same temperature.

  FIG. 12 is a diagram showing isotherms on the surface where the element groups Gr1 to Gr4 are formed in this state by curves Lh1 to Lh4 and Lo1 to Lo4. The temperatures Temp of the isotherms shown by the curves Lh1 to Lh4 are substantially equal to each other. The temperatures of the isotherms shown by the curves Lo1 to Lo4 are also equal to each other and lower than the temperature Temp. Thus, by energizing the heating coils 21 to 24, the heating coils 21 to 24 mainly heat the corresponding element groups Gr <b> 1 to Gr <b> 4 (positioned immediately above the respective heating coils), and the magnetic sensor 10. Since the (chip) is not uniformly heated, the upper surface of the layer S3 on which the element groups Gr1 to Gr4 are formed has a non-uniform temperature below the temperature of the element groups Gr1 to Gr4 when viewed over the entire surface.

  In this state, the control circuit unit 31 acquires the detected temperature of the temperature detection unit 32 at that time as the temperature T2s, and sets the second temperature T2 of the GMR element 18 to T2 = T1s + k · (T2s−T1s) (k is The constant is determined according to a constant correlation between the temperature of the temperature detection unit 32 and the temperature of the GMR element 18 expressed by an equation (a constant determined in advance by experiment). Further, the control circuit unit 31 outputs the X-axis magnetic sensor output value X2 (X-axis magnetic sensor second output value X2) and the Y-axis magnetic sensor output value Y2 (Y-axis magnetic sensor second output value Y2) at that time. And get.

Then, the control circuit unit 31 uses, as data representing the temperature dependence characteristics, gradients (output change amounts per unit temperature change of the magnetoresistive effect element) Mx and My defined by the following equations (1) and (2). Calculation is performed as basic data for temperature dependent characteristic compensation, and the slopes Mx and My are written into the write-once first memory (this function corresponds to the function of the temperature dependent characteristic writing means). In this case, the slope Mx is a “ratio” of the difference between the X-axis magnetic sensor first output value X1 and the X-axis magnetic sensor second output value X2 with respect to the difference between the first temperature T1 and the second temperature T2, and the slope My Is the “ratio” of the difference between the Y-axis magnetic sensor first output value Y1 and the Y-axis magnetic sensor second output value Y2 with respect to the difference between the first temperature T1 and the second temperature T2.
Mx = (X2-X1) / (T2-T1) (1)
My = (Y2-Y1) / (T2-T1) (2)

  Thus, the acquisition of temperature-dependent characteristic compensation basic data at the stage of the magnetic sensor alone is completed. Thereafter, the magnetic sensor 10 is left until it is cooled and proceeds to the next step. FIG. 13 is a graph showing the relationship between the passage of time after the energization of the heating coils 21 to 24 for obtaining the temperature-dependent characteristic compensation basic data and the temperature change of the GMR elements 11 to 18 are completed.

  If a similar temperature change is caused to occur in the GMR elements 11 to 18 using a conventional heating / cooling device, the entire magnetic sensor 10 is heated / cooled. The temperature decrease rate after completion is small, and it may take several minutes to 20 minutes to cool. In contrast, in the present embodiment, since the element groups Gr1 to Gr4 (GMR elements 11 to 18) are mainly heated, the time required to heat the GMR elements 11 to 18 is shortened. In addition, since the rate of temperature decrease after the heating is increased, the necessary cooling is completed in about several seconds as shown in FIG. Therefore, the time required for acquiring the temperature-dependent characteristic compensation basic data is short, and it is possible to proceed to the next manufacturing process within a short time after acquiring the basic data.

  Thereafter, when the manufacturing process necessary for the magnetic sensor 10 alone is completed, the magnetic sensor 10 is mounted (accommodated) in a case 41 of a mobile phone 40 having permanent magnet components such as a speaker 43 and used as a geomagnetic sensor. The As a result, a leakage magnetic field in the same direction is always applied to the magnetic sensor 10 from the permanent magnet component of the mobile phone 40 (regardless of the orientation of the mobile phone 40). Deviation from the zero point) when there is none. In addition, since the X-axis magnetic sensor and the Y-axis magnetic sensor are full bridge circuits, the output of each magnetic sensor has a resistance value of the magnetoresistive effect element constituting the same magnetic sensor (in design, it has the same size). The offset due to the variation itself is also included.

  At this time, the output value of the X-axis magnetic sensor of the magnetic sensor 10 changes in proportion to the temperature T of the GMR elements 11 to 14 constituting the X-axis magnetic sensor, for example, as shown by the one-dot chain line in FIG. . In this case, the slope of the one-dot chain line in FIG. 10 is the same as the slope of the solid line in FIG. Similarly, the output value of the Y-axis magnetic sensor of the magnetic sensor 10 changes in proportion to the temperature T of the GMR elements 15 to 18 constituting the Y-axis magnetic sensor, for example, as shown by the one-dot chain line in FIG. . Also in this case, the slope of the one-dot chain line in FIG. 11 is the same as the slope of the solid line in FIG.

  When the predetermined condition (offset acquisition condition) is established by the user operating the operation unit 45 of the mobile phone 40, the microcomputer 47 of the mobile phone 40 determines the leakage magnetic field and the resistance values of the magnetoresistive effect elements 11-18. Data (offset value) related to the offset of the magnetic sensor 10 (X-axis magnetic sensor, Y-axis magnetic sensor) due to variation is acquired. More specifically, the microcomputer 47 is placed on the liquid crystal display unit 44 on the desk with the front surface of the mobile phone 40 facing upward (that is, the front surface is substantially horizontal and the display unit 44 is directed vertically upward). In that state, a message that prompts the user to press the offset button, which is a specific button of the operation unit 45, to turn the button on is displayed.

  When the above operation is performed by the user, the microcomputer 47 acquires the output values of the X-axis magnetic sensor and the Y-axis magnetic sensor as the X-axis first reference data Sx1 and the Y-axis first reference data Sy1, respectively. The data is stored / stored in a temporary memory (for example, RAM) provided in the microcomputer 47.

  Next, the microcomputer 47 rotates the mobile phone 40 180 degrees on the desk (that is, in a horizontal plane) with the front surface of the mobile phone 40 facing upward on the liquid crystal display unit 44, and then presses the offset button again. A message prompting you to do so is displayed. When such an operation is performed by the user, the microcomputer 47 acquires the output values of the X-axis magnetic sensor and the Y-axis magnetic sensor as the X-axis second reference data Sx2 and the Y-axis second reference data Sy2, respectively, and stores them in the temporary memory. Store and remember.

  The microcomputer 47 stores and stores the average value of the X-axis first reference data Sx1 and the X-axis second reference data Sx2 in the second memory as the X-axis offset reference data X0, and also stores the Y-axis first reference data Sy1. And the average value of the Y-axis second reference data Sy2 are stored and stored in the second memory as Y-axis offset reference data Y0, and the detected temperature T0s of the temperature detection unit 32 at that time is set as the GMR element temperature T0 in the second memory. Store and store in Thus, the average value of the output of each magnetic sensor before and after rotating the mobile phone 40 by 180 ° is stored as the offset reference data X0 and Y0 in order to obtain the offset value by removing the influence of geomagnetism. Since the magnetic sensor 10 is at a uniform temperature (room temperature) at the time of obtaining the detection temperature T0, the detection temperature T0s is equal to the GMR element temperature T0.

Thereafter, the mobile phone 40 returns to the normal use mode and measures the geomagnetism by the magnetic sensor 10 as necessary. At this time, the microcomputer 47 obtains the actual detection temperature TCs of the temperature detection unit 32 as the GMR element temperature TC, and the offset Xoff of the X-axis magnetic sensor at that time according to the following equations (3) and (4) And the offset Yoff of the Y-axis magnetic sensor are estimated. At the time when the detected temperature TCs is acquired, the magnetic sensor 10 is at a uniform temperature (room temperature), so the detected temperature TCs is equal to the GMR element temperature TC.
Xoff = Mx · (TC−T0) + X0 (3)
Yoff = My · (TC−T0) + Y0 (4)

Next, the microcomputer 47 obtains the X-axis magnetic sensor output value XC and the Y-axis magnetic sensor output value YC at that time, and the magnitude of the magnetic field in the X-axis direction according to the following equations (5) and (6). Sx and the magnitude Sy of the magnetic field in the Y-axis direction are obtained, respectively, and the direction of geomagnetism is measured based on Sx and Sy. As described above, the compensation of the temperature dependence characteristic of the magnetic sensor 10 is executed, and the magnetic sensor 10 functions as a geomagnetic sensor.
Sx = XC-Xoff (5)
Sy = YC−Yoff (6)

  As described above, the magnetic sensor 10 according to the first embodiment mainly heats the GMR elements 11 to 18 formed immediately above the heating coils 21 to 24 by the heating coils 21 to 24. (The temperature of the magnetic sensor 10 including the substrate is lower than the temperature of the magnetoresistive effect elements 11 to 18 heated to the same temperature), so the entire magnetic sensor 10 was heated by the heating device. Compared to the case, temperature dependent characteristic compensation basic data for compensating for the temperature dependent characteristic can be acquired within a short time. Therefore, since the possibility that the geomagnetism changes during the measurement of the temperature dependent characteristic compensation basic data is small, the data can be acquired with high accuracy, and as a result, the temperature dependent characteristic of the magnetic sensor 10 is compensated with high accuracy. be able to. In addition, since the magnetic sensor 10 can be cooled within a short time compared to the case where the magnetic sensor 10 is cooled after being heated by the heating device, the time required for manufacturing the magnetic sensor 10 can be shortened and the manufacturing cost can be reduced. it can.

  By the way, in a magnetic sensor using a magnetoresistive effect element such as a GMR element, when a large external magnetic field is applied to the magnetic sensor, the magnetization direction of the free layer of the magnetoresistive effect element does not return to the initial state. Sometimes. For this reason, an initialization coil is disposed immediately below the magnetoresistive effect element, and energization is performed when a predetermined condition is satisfied in the coil (for example, when a specific switch of the operation unit 45 is operated). It is preferable to configure the magnetic sensor so that the direction of magnetization of the free layer can be returned to the initial state by the generated magnetic field.

  In such a case, the magnetic sensor can include the initialization coil independently of the heating coils 21 to 24. For example, the initialization coil can be formed in a layer (layer S1 or layer S2) different from the layer in which the heating coils 21 to 24 are formed (layer S3 in this example). Thus, if the initialization coil and the heating coil are provided independently, the shape of the heating coil can be designed to a desired shape (a shape suitable for heating). For example, the heating coil may be a folded heater (heating element) in which one end of the coil is not disposed at the center of the coil. Further, instead of the heating coil, a plate-like heater (heating element) may be employed.

  On the other hand, the heating coils 21 to 24 can be used as initialization coils as described above. In this case, it is not necessary to separately form an initialization coil, and the manufacturing cost of the magnetic sensor 10 can be reduced. In addition, since the heating of the elements 11 to 18 and the initialization of the elements 11 to 18 for acquiring the basic data for temperature characteristic compensation can be performed simultaneously by energizing the heating coils 21 to 24 once, The process is simplified and the manufacturing cost can be reduced.

  On the other hand, as described above, the magnetic sensor using the magnetoresistive effect elements such as the GMR elements 11 to 18 calculates the azimuth by calculating the output value of the magnetoresistive effect element that changes according to the external magnetic field. It is also used as a geomagnetic sensor. In such a case, it is necessary to inspect at the time of shipment or the like whether the magnetoresistive effect element functions correctly under an external magnetic field.

  In such an inspection, it is necessary to apply a known external magnetic field to the magnetoresistive effect element. For this purpose, it is conceivable to prepare equipment for generating an external magnetic field. However, such equipment is expensive. On the other hand, an inspection coil is disposed near (for example, directly below) the magnetoresistive element, and an external magnetic field for the inspection is applied to the magnetoresistive element by energizing the inspection coil. It can also be configured as follows.

  In such a case, the magnetic sensor 10 can include the inspection coil independently of the heating coils 21 to 24. For example, the inspection coil may be formed in a layer (layer S1 or layer S2) different from the layer in which the heating coils 21 to 24 are formed (in this example, the layer S3). Thus, if the inspection coil and the heating coil are provided independently, the shape of the heating coil can be designed to a desired shape (a shape suitable for heating). For example, the heating coil may be a folded heater (heating element) in which one end of the coil is not disposed at the center of the coil. Further, instead of the heating coil, a plate-like heater (heating element) may be employed.

  On the other hand, the heating coils 21 to 24 can be used as the above-described inspection coils by rotating the coils 21 to 24 by 90 ° in a plan view. In this case, it is not necessary to form a separate inspection coil, and the cost of the magnetic sensor 10 can be reduced.

  In the magnetic sensor 10, the heating coil 21 (22 to 24) includes a first conductor 21-1 that forms a spiral in plan view, and a second conductor 21-2 that forms a spiral in plan view. The element groups Gr1 to Gr4 are arranged between the vortex center P1 of the first conductor and the vortex center P2 of the second conductor in plan view, and in plan view with any one of the element groups So that currents in substantially the same direction flow through the portion of the first conducting wire located in the overlapping portion and the portion of the second conducting wire located in the portion overlapping with any one of the magnetic element groups in plan view. The first conducting wire and the second conducting wire are connected.

  As a result, a large magnetic field (for example, a magnetic field having a magnitude necessary for initialization) is generated while reducing the area in plan view of the heating coils 21 to 24 that also function as the initialization coil (or inspection coil). Since it can add to the magnetoresistive effect elements 11-18, the magnetic sensor 10 can be reduced in size.

  In the first embodiment, when the GMR element is heated, the heating coils 21 to 24 are energized in order of 100 mA every 100 ms. However, for example, the heating coils 21 to 24 have a current of 25 mA, for example. These currents may be simultaneously supplied for 400 ms. When energized at the same time in this way, an advantage is obtained that the temperature balance between the heating coils 21 to 24 becomes better than when energized sequentially.

(Second Embodiment)
Next, about the magnetic sensor 50 which concerns on 2nd Embodiment by this invention, it is the fragmentary sectional view which cut | disconnected the magnetic sensor 50 in the plane along the 1-1 line | wire of FIG. 14 and FIG. 14 which showed the top view. This will be described with reference to FIG. The magnetic sensor 50 is a first embodiment in that a heating coil 70 for heating the GMR elements 11 to 18 (element groups Gr1 to Gr4) is provided independently of the initialization coils 61 to 64. It differs from the magnetic sensor 10 which concerns on a form. Therefore, the difference will be mainly described below.

  The initialization coils 61 to 64 shown in FIGS. 14 and 15 are the same as the heating coils 21 to 24, respectively, in the layer S3 immediately below the element groups Gr1 to Gr4 (on the Z-axis negative direction side). Each is buried. These initialization coils 61 to 64 are energized under a predetermined condition (for example, before the start of magnetic detection, etc.) with a predetermined orientation (on a free layer of the magnetoresistive effect element provided above each heating coil). A magnetic field (initializing magnetic field) having a direction perpendicular to the pinned magnetization direction of the pinned layer is generated.

The heating coil 70 is made of, for example, a thin film of aluminum and has a spiral shape (not shown) in plan view. The outer shape of the heating coil 70 has a substantially square shape in which each side is parallel to each side of the square formed by the bridge wiring portion 19, and the center of gravity coincides with the center of gravity of the square formed by the bridge wiring portion 19. The heating coil 70 is formed inside the bridge wiring portion 19 in plan view. As can be understood from FIG. 15, the heating coil 70 includes a layer S3 in which GMR elements 11 to 18 are formed on the upper surface of the insulating layer INS1 and the wiring layers S1 to S3 sequentially stacked on the substrate 50a. It is embedded and formed in (the uppermost layer S3 of the layers S1 to S3 functioning as a wiring layer).
Further, in the heating coil 70, the amount of heat transmitted from the heating coil 70 to any one of the plurality of GMR elements 11 to 18 is changed from the heating coil 70 to the plurality of magnetoresistive effect elements 11. It is formed so as to be substantially the same as the amount of heat transferred to one of the other elements.

  In the magnetic sensor 50 as well, the temperature dependent characteristics are compensated in the same manner as the magnetic sensor 10. That is, the heating coil 70 is energized in order to obtain the ratios (inclinations) Mx and My, which are basic data for compensating temperature dependent characteristics, at the stage of the magnetic sensor alone. FIG. 16 shows the isotherm on the surface where the element groups Gr1 to Gr4 are formed in this case by curves Lj1 and Lj2. The temperature of the isotherm indicated by the curve Lj1 is higher than the temperature of the isotherm indicated by the curve Lj2.

  That is, the heating coil 70 mainly heats the element groups Gr <b> 1 to Gr <b> 4 by energizing the heating coil 70. As a result, the element groups Gr1 to Gr4 have substantially the same temperature. On the other hand, when the element groups Gr1 to Gr4 are heated to a temperature sufficient to acquire the temperature-dependent characteristic compensation basic data, the entire magnetic sensor 50 including the substrate 50a is not uniformly heated. The upper surface of the layer S3 on which the element groups Gr1 to Gr4 are formed is heated at a non-uniform temperature due to the heat generated by the coil 70 for use.

  In other words, in this magnetic sensor 50, when acquiring temperature-dependent characteristic compensation basic data, the GMR elements 11 to 18 are not heated until the entire magnetic sensor 50 including the substrate 50a has the same temperature ( Therefore, the time required for heating and cooling the GMR elements 11 to 18 can be shortened as compared with the case where the entire magnetic sensor 50 is heated by a heating device.

  Therefore, according to the magnetic sensor 50, the temperature-dependent characteristic compensation basic data can be acquired within a short time, and since the possibility that the geomagnetism changes during the measurement of the data is small, the data is acquired with high accuracy. be able to. As a result, the temperature dependence characteristics of the magnetic sensor 50 can be accurately compensated.

  Further, since the magnetic sensor 50 can be cooled within a short time compared to the case where the magnetic sensor 50 is cooled after being heated by the heating device, the time required for manufacturing the magnetic sensor 50 can be shortened and the manufacturing cost can be reduced. Can be reduced. Furthermore, since the heating coil 70 is embedded in the uppermost layer S3 closest to the GMR elements 11 to 18 among the three wiring layers S1 to S3, the GMR elements 11 to 18 can be efficiently heated. Can do.

  Instead of the initialization coils 61 to 64, the above-described inspection coil may be disposed in the same portion as the initialization coils 61 to 64. Further, the initialization coils 61 to 64 and the heating coils 70 may be independent of the initialization coils 61 to 64 and the inspection coils may be formed immediately below the initialization coils 61 to 64. Further, the initialization coil may be formed in a lower layer such as the layer S1, and the inspection coil may be formed in an upper layer such as the layer S3.

  As described above, according to the magnetic sensor and the temperature dependence characteristic compensation method of the magnetic sensor according to the present invention, the temperature dependence characteristic of the magnetic sensor can be compensated with high accuracy. The magnetic sensors 10 and 50 including the X-axis magnetic sensor and the Y-axis magnetic sensor are each configured by a full bridge circuit, and the temperature-dependent characteristics thereof change in proportion to the temperature change of the magnetoresistive effect element. In view of the above, since the Mx and My, which are the above-mentioned “ratio”, are stored in the write-once memory of the magnetic sensor, after the magnetic sensor is mounted on another electronic device, the electronic device By reading out the “ratio” from the memory, it is possible to obtain data on the temperature-dependent characteristics of the mounted magnetic sensor, and it is possible to compensate for the temperature-dependent characteristics of the magnetic sensor using the data.

  Further, only by storing the “ratio” (inclination Mx, My) in the memory of the magnetic sensors 10 and 50, it is possible to store data on the temperature-dependent characteristics of each magnetic sensor. Therefore, the capacity of the memory can be reduced as compared with the case where only a plurality of sets of data consisting of the element temperature and the magnetic sensor output are stored in the memory. Further, since the “ratio” (inclinations Mx, My) does not change, the memory can be made an inexpensive write-once type. As a result, the cost of the magnetic sensor can be reduced.

  In addition, this invention is not limited to the said embodiment, A various modification can be employ | adopted within the scope of the present invention. For example, a TMR element can be employed as the magnetoresistive effect element of the magnetic sensors 10 and 50 instead of the GMR element. The electronic device on which the magnetic sensors 10 and 50 are mounted is not limited to a mobile phone, but may be a mobile computer, a portable navigation system, or a PDA (personal information device “Personal Digital Assistants”).

  In each of the above embodiments, before energizing the heating coils 21 to 24 and 70, the first temperature T1, the X-axis magnetic sensor first output value X1, and the output value of the Y-axis magnetic sensor of the GMR element 18. After obtaining Y1 and energizing the heating coils 21 to 24, 70, the second temperature T2, the X-axis magnetic sensor second output value X2, and the Y-axis magnetic sensor second output value Y2 of the GMR element 18 are obtained. Thus, the gradients Mx and My are obtained. However, after the heating coils 21 to 24 and 70 are energized, the first temperature T1, the X-axis magnetic sensor first output value X1, and the Y-axis magnetic field of the GMR element 18 are obtained. After the sensor output value Y1 is acquired and then the energization is stopped, the second temperature T2, the X-axis magnetic sensor second output value X2, and the Y-axis magnetic sensor No. 2 The output value Y2 is acquired and the slope Mx My may be obtained.

  Furthermore, as shown in FIG. 17, instead of the heating coil 70 of the second embodiment, a heating coil 80 having a pattern in which the central portion of the heating coil 70 is removed may be employed. According to the heating coil 80, the magnetoresistive elements 11 to 18 can be heated to substantially the same temperature by energizing the heating coil 80, while excessively heating the central portion of the magnetic sensor 50 (substrate 50a). Therefore, the GMR elements 11 to 18 can be heated more efficiently.

  Further, the heating coil, the initialization coil, and the inspection coil may be provided independently so as to be laminated immediately below each GMR element group. In this case, for example, as shown in FIG. 18, the INS1 layer and the four wiring layers S1 to S4 are sequentially laminated on the substrate, and the heating coil 101, the initialization coil 102, and the inspection coil 103 are layered. You may make it provide in S4, layer S3, and layer S1. Further, the bridge wiring may extend over a plurality of layers.

  Furthermore, the present invention is not only a two-axis direction detection type magnetic sensor of an X-axis magnetic sensor and a Y-axis magnetic sensor, but also a three-axis direction detection type including an X-axis magnetic sensor, a Y-axis magnetic sensor, and a Z-axis magnetic sensor. It can also be applied to a magnetic sensor or a uniaxial direction detection type magnetic sensor.

FIG. 1 is a schematic plan view of a magnetic sensor according to the first embodiment of the present invention. FIG. 2 is a partial schematic plan view of the magnetic sensor showing the electrical connection state of the magnetic sensor shown in FIG. 3 is a partial schematic cross-sectional view of the magnetic sensor cut along a predetermined plane orthogonal to the plane of each layer constituting the magnetic sensor shown in FIG. FIG. 4 is a graph showing a change in resistance value of the GMR element shown in FIG. 1 with respect to an external magnetic field. FIG. 5 is a schematic plan view of a magnetic sensor according to a modification of the first embodiment. FIG. 6 is a partially enlarged plan view of the magnetic sensor shown in FIG. FIG. 7 is an equivalent circuit diagram of the X-axis magnetic sensor constituting the magnetic sensor shown in FIG. FIG. 8 is a graph showing a change in output voltage (output signal) with respect to an external magnetic field of the X-axis magnetic sensor constituting the magnetic sensor shown in FIG. FIG. 9 is a front view of a mobile phone on which the magnetic sensor shown in FIG. 1 is mounted. FIG. 10 is a graph showing temperature dependence characteristics of the X-axis magnetic sensor constituting the magnetic sensor shown in FIG. FIG. 11 is a graph showing temperature dependence characteristics of the Y-axis magnetic sensor constituting the magnetic sensor shown in FIG. FIG. 12 is a schematic plan view of the magnetic sensor showing the isotherm when the heating coil of the magnetic sensor shown in FIG. 1 is energized. FIG. 13 is a graph showing the relationship between the passage of time after energizing the heating coil of the magnetic sensor shown in FIG. 1 and the temperature change of the GMR element. FIG. 14 is a schematic plan view of a magnetic sensor according to the second embodiment of the present invention. 15 is a partial cross-sectional view of the magnetic sensor cut along a plane along line 1-1 in FIG. FIG. 16 is a schematic plan view of the magnetic sensor showing an isotherm when the heating coil of the magnetic sensor shown in FIG. 14 is energized. FIG. 17 is a schematic plan view of the magnetic sensor showing the isotherm when the heating coil of the magnetic sensor according to the modification of the second embodiment of the present invention is energized. FIG. 18 is a schematic sectional view of another modification of the magnetic sensor according to the present invention.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 10,50 ... Magnetic sensor, 10a ... Substrate, 10a1 ... Element isolation region, 10a2 ... Element activation region, 11-18 ... Magnetoresistive effect element (GMR element), 19 ... Bridge wiring part, 21-24 ... Heating coil , 31 ... control circuit part, 32 ... temperature detection part, 33a to 33d ... coil for inspection, 40 ... mobile phone, 61 to 64 ... coil for initialization.

Claims (7)

Single substrate, a plurality of magnetoresistive effect elements to obtain the plurality of bridge wiring section magnetoresistive element bridging connection, the physical quantity based on the resistance value before Symbol plurality of magnetoresistive element via the wiring part A magnetic sensor comprising a control circuit unit that generates an output signal to be output to the outside by processing the same physical quantity and a pad for connecting the control circuit unit to an external device ,
In plan view
An element region in which the plurality of magnetoresistive elements are formed;
A bridge wiring part region in which the bridge wiring part is formed;
An LSI region in which the control circuit unit is formed;
A pad region for outputting an output signal from the control circuit unit;
Have
And the magnetic sensor is
A plurality of layers in which a layer composed of a conductive film and an interlayer insulating film is stacked on the substrate ;
Furthermore,
Before SL magnetoresistive element is the above element region is formed on the upper surface of one layer of said plurality of layers,
The control circuit unit is formed in the LSI area on the substrate,
The bridge wiring portion is formed in the plurality of layers below the magnetoresistive effect element in the bridge wiring portion region.
Wherein the magnetoresistance effect element and the bridge wiring section intersecting the layer surfaces of the same layer of a conductive film and the multiple layers in the crossing a boundary between the element region and the bridge wiring region within the plurality of layers are connected to each other by a connecting portion made of a conductive material extending in a direction, and the conductive said bridge wiring section and said control circuit section crossing the boundary between said bridge wiring region within the plurality of layers the LSI region magnetic sensors connected to each other by a connecting portion made of a conductive material extending in a direction intersecting the layer surfaces of the same layer at the membrane and the plurality of layers.   The magnetic sensor according to claim 1,
  The bridge wiring portion is formed in a wiring layer that is one layer of the plurality of layers and includes a plurality of wirings that form a closed curve. The bridge wiring portion and the magnetoresistive effect element include other wiring layers. A magnetic sensor connected through the conductive film formed in the layer.   The magnetic sensor according to claim 2,
  The plurality of magnetoresistive elements are magnetic sensors arranged in a peripheral portion of the substrate in plan view and outside the bridge wiring portion.   The magnetic sensor according to claim 3.
  The control circuit unit is a magnetic sensor disposed substantially inside the closed curve in a plan view.   The magnetic sensor according to any one of claims 1 to 4,
  The magnetoresistive effect element comprises a plurality of element groups composed of a pair of magnetoresistive effect elements having the same magnetization direction of the pinned layer,
  Each of the plurality of element groups is
  The magnetization directions of the pinned layers of at least two of the element groups are orthogonal to each other;
  The pinned layer has a magnetization direction substantially parallel to a direction in which the distance from the center of gravity of the substrate increases in a plan view, and the pair of magnetoresistive elements are adjacent to each other. Magnetic sensor disposed in   The magnetic sensor according to claim 5,
  The substrate has a substantially square or rectangular shape in plan view,
  Each of the plurality of element groups is arranged along each of the four sides of the substrate in plan view,
  A magnetic sensor in which element groups formed on opposing sides of the four sides are bridge-connected.   The magnetic sensor according to claim 5 or 6,
  In each of the plurality of element groups, the direction of magnetization of the free layer when the external magnetic field is not applied is substantially perpendicular to the direction in which the distance from the center of gravity of the substrate increases in plan view. And a magnetic sensor disposed on the same substrate so that the pair of magnetoresistive elements are adjacent to each other.

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