JP2014006053A - Magnetic sensor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a magnetic sensor capable of suppressing variation on working points.SOLUTION: A magnetic sensor 1 includes a serial circuit 9 configured by serially connecting first and second magneto-resistive elements R1 and R2. A power supply voltage Vcc is applied to the serial circuit 9. The first magneto-resistive element R1 and the second magneto-resistive element R2 are serially connected via an electrode pad 4 for taking out an output voltage Vout. The electrode pad 4 and the first magneto-resistive element R1 are electrically connected to each other via a first wiring pattern 3A. The electrode pad 4 and the second magneto-resistive element R2 are electrically connected to each other by a second wiring pattern 3B. The first wiring pattern 3A and the second wiring pattern 3B are formed separately from each other.

Description

  The present invention relates to a magnetic sensor that detects a magnetic field using a magnetoresistive element.

  In general, a magnetic sensor formed by connecting four magnetoresistive elements to a Wheatstone bridge is known (for example, see Patent Document 1). Such a conventional magnetic sensor will be described with reference to FIG.

  Four magnetoresistive elements R11 to R14 constituting the magnetic sensor 41 are provided on the surface of the substrate 42 to form a bridge circuit 43. The first to fourth magnetoresistive elements R11, R12, R13, and R14 are each formed in a meander shape by connecting long strip patterns and short strip patterns alternately and orthogonally. In the first and third magnetoresistive elements R11 and R13, the short strip pattern extends in the Y direction, and the long strip pattern extends in the X direction. For this reason, the change in resistance value of the first and third magnetoresistive elements R11 and R13 is the largest for the magnetic field applied in the Y direction and the smallest for the magnetic field applied in the X direction. That is, the first and third magnetoresistive elements R11 and R13 have maximum sensitivity to the magnetic field applied in the Y direction. In the second and fourth magnetoresistive elements R12 and R14, the short strip pattern extends in the X direction, and the long strip pattern extends in the Y direction. For this reason, the change in resistance value of the second and fourth magnetoresistive elements R12 and R14 is the largest for the magnetic field applied in the X direction and the smallest for the magnetic field applied in the Y direction. That is, the second and fourth magnetoresistive elements R12 and R14 have maximum sensitivity to the magnetic field applied in the X direction.

  The first magnetoresistive element R11 and the second magnetoresistive element R12 are connected in series via the first connection end P11 and the wiring pattern WP1 to form a first series circuit (half-bridge circuit) 44. The third magnetoresistive element R13 and the fourth magnetoresistive element R14 are connected in series via the third connection end P13 and the wiring pattern WP3 to form a second series circuit (half-bridge circuit) 45. . Further, the second magnetoresistive element R12 side of the first series circuit 44 and the third magnetoresistive element R13 side of the second series circuit 45 are connected in common via the second connection end P12 and the wiring pattern WP2. At the same time, the first magnetoresistive element R11 side of the first series circuit 44 and the fourth magnetoresistive element R14 side of the second series circuit 45 are connected via the fourth connection end P14 and the wiring pattern WP4. Commonly connected to form a full bridge circuit. The power supply voltage Vcc is applied to the second connection end P12, and the fourth connection end P14 is connected to the ground GND, and the first connection end P11 and the third connection end P13 are used according to the magnetic field strength. The output voltages Vm and Vp are taken out. The output voltages Vm and Vp are differentially amplified via a differential amplifier (not shown).

  Next, the output voltages Vm and Vp of the magnetic sensor 41 when the magnetic field strength of the magnetic field in the Y direction, for example, applied to the magnetic sensor 41 is changed will be described with reference to FIG.

  When the magnetic field intensity in the Y direction is gradually increased and applied to the magnetic sensor 41, the resistance values of the first and third magnetoresistive elements R11 and R13 decrease. On the other hand, since the X-direction component is not applied to the second and fourth magnetoresistive elements R12 and R14, the resistance values of the second and fourth magnetoresistive elements R12 and R14 hardly change. As a result, the output voltage Vm decreases and the output voltage Vp increases. That is, the output voltages Vm and Vp change in opposite phases. The resistance values of the first to fourth magnetoresistive elements R11 to R14 are set so that the output voltage Vm is higher than the output voltage Vp when no magnetic field in the Y direction is applied to the magnetic sensor 41.

  Therefore, for example, when the magnetic field strength of the magnetic field in the Y direction is gradually increased, the output voltages Vm and Vp cross at ± Ba [mT]. Therefore, the detection signal of the magnetic sensor 41 can detect the magnetic field in the Y direction with the magnetic field strength ± Ba [mT] at which the output voltages Vm and Vp are reversed as the operating point (threshold) of the magnetic sensor. it can. Note that the magnetic field can be detected in the same manner when the magnetic field strength in the magnetic field direction other than the Y direction is changed.

JP 7-297463 A

  By the way, in the magnetic sensor described above, even if the resistance values of the first to fourth magnetoresistive elements R11 to R14 are accurately made according to the design values, the measured curves of the output voltages Vm and Vp are determined from the design target curve. There was a case to shift. For this reason, the magnetic field intensity at which the output voltages Vm and Vp are reversed varies for each magnetic sensor, resulting in a problem that the detection sensitivity of the magnetic sensor 41 is not constant.

  The present invention has been made in view of the above-described problems, and an object of the present invention is to provide a magnetic sensor that suppresses variations in operating points of the magnetic sensor.

  In order to solve the above problems, the invention of claim 1 is characterized in that a first magnetoresistive element whose resistance value changes to the maximum with respect to an applied magnetic field in a first direction and a second magnetoresistive element different from the first direction. A second magnetoresistive element whose resistance value changes to the maximum with respect to the applied magnetic field in the direction, an electrode pad, and a first wiring pattern that electrically connects the electrode pad and the first magnetoresistive element; A second wiring pattern formed separately from the first wiring pattern and electrically connecting the electrode pad and the second magnetoresistive element, and the first magnetoresistive element and the first wiring pattern A magnetic sensor having at least one series circuit in which two magnetoresistive elements are connected in series, the resistance value of the first wiring pattern being added to the resistance value of the first magnetoresistive element, The resistance value of the second magnetoresistive element to the second wiring pattern Resistance is characterized in that it is added in.

  According to a second aspect of the present invention, the first and third magnetoresistive elements whose resistance values change to the maximum with respect to the applied magnetic field in the first direction, and the applied magnetic field in the second direction different from the first direction are used. In contrast, the second and fourth magnetoresistive elements whose resistance values change to the maximum, the first to fourth electrode pads, and the first electrode pad and one end of the first magnetoresistive element are electrically connected A first wiring pattern to be connected, and a second wiring pattern formed separately from the first wiring pattern and electrically connecting the first electrode pad and one end of the second magnetoresistive element; A third wiring pattern for electrically connecting the second electrode pad and the other end of the second magnetoresistive element, and the second electrode pad formed separately from the third wiring pattern. And a fourth wiring pattern for electrically connecting one end of the third magnetoresistive element A fifth wiring pattern for electrically connecting the third electrode pad and the other end of the third magnetoresistive element, and the third electrode formed separately from the fifth wiring pattern. A sixth wiring pattern that electrically connects one end of the pad and the fourth magnetoresistive element; and a seventh wiring pattern that electrically connects the fourth electrode pad and the other end of the fourth magnetoresistive element. An eighth wiring pattern formed separately from the seventh wiring pattern and electrically connecting the fourth electrode pad and the other end of the first magnetoresistive element; A first series circuit in which the first magnetoresistive element and the second magnetoresistive element are connected in series, and a second series in which the third magnetoresistive element and the fourth magnetoresistive element are connected in series. And a series circuit of the first magnetoresistive element. Each resistance value of the first wiring pattern and the eighth wiring pattern is added to the resistance value, and each resistance value of the second wiring pattern and the third wiring pattern is added to the resistance value of the second magnetoresistive element. The resistance value is added, the resistance values of the fourth wiring pattern and the fifth wiring pattern are added to the resistance value of the third magnetoresistance element, and the resistance value of the fourth magnetoresistance element is added to the resistance value of the fourth magnetoresistance element. Each resistance value of the sixth wiring pattern and the seventh wiring pattern is added.

  According to a third aspect of the present invention, in the magnetic sensor according to the first or second aspect, the separated wiring patterns are formed in substantially the same shape.

  In the first aspect of the present invention, the electrode pad and the first magnetoresistive element are electrically connected via the first wiring pattern. Further, the electrode pad and the second magnetoresistive element are electrically connected through a second wiring pattern formed separately from the first wiring pattern. For this reason, since the first magnetoresistive element and the first wiring pattern are connected in series, the resistance value of the first wiring pattern is added to the resistance value of the first magnetoresistive element. Further, since the second magnetoresistive element and the second wiring pattern are connected in series, the resistance value of the second wiring pattern is added to the resistance value of the second magnetoresistive element. As a result, the ratio that the resistance value of the first wiring pattern contributes to the total resistance value of the path of the first magnetoresistive element to the first wiring pattern to the electrode pad is constant, and the electrode pad to the second wiring pattern. The ratio that the resistance value of the second wiring pattern contributes to the total resistance value of the path of the second magnetoresistive element is constant. Accordingly, the variation range of the output voltage at the operating point (threshold value) of the magnetic sensor can be suppressed, so that the variation in the detected magnetic field of the magnetic sensor can be suppressed.

  In the invention of claim 2, each electrode pad and the end portions of the two magnetoresistive elements arranged adjacent to each other do not have a common portion, but are separated through a wiring pattern formed separately. Electrically connected. For this reason, the first magnetoresistive element, the first wiring pattern, and the eighth wiring pattern are connected in series. In addition, the second magnetoresistive element, the second wiring pattern, and the third wiring pattern are connected in series. The third magnetoresistive element, the fourth wiring pattern, and the fifth wiring pattern are connected in series. In addition, the fourth magnetoresistance element, the sixth wiring pattern, and the seventh wiring pattern are connected in series. That is, the resistance values of the first wiring pattern and the eighth wiring pattern are added to the resistance value of the first magnetoresistive element. Further, the resistance values of the second wiring pattern and the third wiring pattern are added to the resistance value of the second magnetoresistive element. Further, the resistance values of the fourth wiring pattern and the fifth wiring pattern are added to the resistance value of the third magnetoresistive element. Further, the resistance values of the sixth wiring pattern and the seventh wiring pattern are added to the resistance value of the fourth magnetoresistive element.

  Accordingly, the total resistance value of the two paths from the electrode pad to which the power supply voltage is applied to each electrode pad from which the output voltage is taken out, and the two resistance pads from each electrode pad from which the output voltage is taken out to the electrode pad connected to the ground The contribution ratio of the resistance value of the wiring pattern to the total resistance value of the path is constant. As a result, the voltage variation range of the output voltage can be suppressed, so that variations in the magnetic field detected by the magnetic sensor can be suppressed.

  In the invention of claim 3, the wiring patterns formed separately are patterned in substantially the same shape. At this time, since the etching error of the wiring pattern occurs in the same manner, the variation of the resistance value between the two becomes extremely small, and the ratio of the resistance value of the wiring pattern to the total resistance value is constant. Accordingly, the voltage variation range of the output voltage can be further suppressed, so that the variation in the detected magnetic field of the magnetic sensor can be further suppressed.

It is a figure which shows the half-bridge type magnetic sensor based on the 1st Embodiment of this invention. It is a figure which shows the magnetic sensor which is a half-bridge type comparative example. It is a characteristic view which shows the relationship between the intensity | strength of the magnetic field of a Y direction, and an output voltage based on a half-bridge type magnetic sensor. It is a figure which shows the full bridge type magnetic sensor based on the 2nd Embodiment of this invention. It is a characteristic view which shows the relationship between the intensity | strength of the magnetic field of a Y direction, and an output voltage regarding a full bridge type magnetic sensor. It is a figure which shows the conventional magnetic sensor. It is a characteristic view which shows the relationship between the intensity | strength of the magnetic field of a Y direction, and an output voltage based on the conventional magnetic sensor.

  Hereinafter, a magnetic sensor according to an embodiment of the present invention will be described in detail with reference to the accompanying drawings.

  FIG. 1 shows a magnetic sensor 1 according to the first embodiment. The magnetic sensor 1 includes a substrate 2, a first magnetoresistive element R1, and a second magnetoresistive element R2. The substrate 2 extends along, for example, the X and Y directions orthogonal to each other, and the first and second magnetoresistive elements R1 and R2 are formed on the surface thereof.

  Each of the first and second magnetoresistive elements R1, R2 is formed in a meander shape by connecting long strip patterns and short strip patterns alternately and orthogonally. The extending direction of the long strip pattern in the first magnetoresistive element R1 extends along the X direction, and the resistance value becomes the smallest when a detection magnetic field in the Y direction that is the first direction is given. On the other hand, the extending direction of the long strip pattern in the second magnetoresistive element R2 extends along the Y direction, and the resistance value becomes the smallest when a detection magnetic field in the X direction which is the second direction is given. The first and second magnetoresistive elements R 1 and R 2 are formed in a predetermined shape using a micro processing technique such as a photolithography technique after a permalloy (NiFe), which is a magnetoresistive material, is formed on the substrate 2, for example. Is patterned.

  One end of the first magnetoresistive element R1 is electrically connected to the electrode pad 4 for taking out the output voltage Vout through the first wiring pattern 3A. One end side of the second magnetoresistive element R2 is electrically connected to the electrode pad 4 via a second wiring pattern 3B formed separately in the vicinity of the first wiring pattern 3A. The other end of the first magnetoresistive element R 1 is electrically connected to the electrode pad 6 connected to the ground via the third wiring pattern 5. The other end of the second magnetoresistive element R2 is electrically connected to an electrode pad 8 for applying a power supply voltage Vcc via a fourth wiring pattern 7. The electrode pads 4, 6, 8 and the wiring patterns 3 A, 3 B, 5, 7 are formed by depositing a conductive metal material such as aluminum on the substrate 2 by vacuum evaporation, sputtering, CVD, etc., and then photolithography. Patterning is performed in a predetermined shape using a fine processing technique such as a technique. Usually, the first wiring pattern 3A and the second wiring pattern 3B are formed to have substantially the same dimensions, for example, the film thickness, the line width, and the line length, and are arranged adjacent to each other. Errors occur in the same way. For this reason, the difference in resistance value between the first wiring pattern 3A and the second wiring pattern 3B is extremely small.

  The first and second magnetoresistive elements R1, R2 are connected in series via the first wiring pattern 3A, the second wiring pattern 3B, and the electrode pad 4 to form a series circuit (half-bridge circuit) 9. . Therefore, when the power supply voltage Vcc is applied between the electrode pad 6 and the electrode pad 8, the electrode pad 4 to the electrode pattern 6 to the wiring pattern 5 to the first magnetoresistive element R1 to the first wiring pattern 3A to the electrode. The first total resistance value corresponding to the path of the pad 4 and the second total value corresponding to the path of the electrode pad 8 to the wiring pattern 7 to the second magnetoresistive element R2 to the second wiring pattern 3B to the electrode pad 4. The output voltage Vout obtained by dividing the power supply voltage Vcc is taken out according to the resistance value.

  Next, the magnetic field detection operation of the magnetic sensor 1 will be described. In addition, unlike the present invention, the wiring pattern is not formed separately into the first wiring pattern 3A and the second wiring pattern 3B, but one common wiring pattern is used. A description will be given while comparing with a magnetic sensor 11 of a comparative example patterned substantially the same as the magnetic sensor 1.

  The form of the magnetic sensor 11 of the comparative example will be described with reference to FIG. In addition, the same code | symbol is attached | subjected to the same component as the magnetic sensor 1 in the magnetic sensor 11, and while the description is abbreviate | omitted, only a different part from the magnetic sensor 1 is demonstrated.

  One end side of the first magnetoresistive element R1 in the magnetic sensor 11 is electrically connected to the tip end of the first branch wiring pattern 12B formed by bifurcating one end side of the main body wiring pattern 12A. Further, one end side of the second magnetoresistive element R2 in the magnetic sensor 11 is electrically connected to the tip end of the second branch wiring pattern 12C in which one end side of the main body wiring pattern 12A is branched into two. The other end side of the main body wiring pattern 12 </ b> A is electrically connected to the electrode pad 4.

  When the power supply voltage Vcc is applied between the electrode pad 6 and the electrode pad 8 in the magnetic sensor 11, the electrode pad 6 to the wiring pattern 5 to the first magnetoresistive element R 1 to the first branch wiring pattern are applied from the electrode pad 4. 12B to body wiring pattern 12A to third total resistance value in the path of electrode pad 4, electrode pad 8 to wiring pattern 7 to second magnetoresistive element R2 to second branch wiring pattern 12C to body wiring pattern 12A to The output voltage Vout obtained by dividing the power supply voltage Vcc is taken out by the fourth total resistance value in the path of the electrode pad 4.

  In the magnetic sensor 1 of the present invention and the magnetic sensor 11 of the comparative example, the first and second magnetoresistive elements R1 and R2 are made of permalloy, and the resistance value thereof is 1.5 kΩ. In the magnetic sensor 1 of the present invention and the magnetic sensor 11 of the comparative example, the wiring patterns 5 and 7 each have a line width of 15 μm, the line length of 100 μm, and the electrode pads 4, 6 and 8 all have a square of 60 μm. The first and second wiring patterns 3A and 3B in the magnetic sensor 1 of the present invention both have a line width of 15 μm and a line length of 400 μm. On the other hand, in the magnetic sensor 11 of the comparative example, the main body wiring pattern 12A has a line width of 15 μm and the line length of 300 μm, and the first branch wiring pattern 12B and the second branch wiring pattern 12C both have a line width of 15 μm, The line length was 100 μm. The wiring patterns 3A, 3B, 5, 7, 12A to 12C and the electrode pads 4, 6, and 8 in the magnetic sensor 1 of the present invention and the magnetic sensor 11 of the comparative example all use vapor deposited films of aluminum.

  Next, with reference to FIG. 3, the output voltage Vout when the magnetic field φ in the Y direction is applied to the magnetic sensor 1 of the present invention and the magnetic sensor 11 of the comparative example with a gradually large variation will be described.

  A magnetic field φ in the Y direction in the + (plus) direction is applied to the magnetic sensor 1 of the present invention and the magnetic sensor 11 of the comparative example. At this time, as the strength of the magnetic field φ increases, the resistance value of the first magnetoresistive element R1 decreases in both the magnetic sensor 1 of the present invention and the magnetic sensor 11 of the comparative example, but the resistance of the second magnetoresistive element R2 decreases. The resistance value hardly changes. For this reason, the output voltage Vout taken out from the electrode pad 4 decreases as the intensity of the magnetic field φ in the Y direction in the + direction increases as indicated by the design target curve C0 indicated by the solid line. In addition, when a magnetic field φ in the Y direction in the − (minus) direction, which is different from the + direction by 180 degrees, is applied, the output characteristics are the same as those in the magnetic field φ in the + direction Y direction.

  From the electrode pad 4 in the magnetic sensor 1 of the present invention, the first total resistance value and the second total resistance value are used, and from the electrode pad 4 of the magnetic sensor 11 of the comparative example, a third total resistance value is used. And the fourth total resistance value, the output voltage Vout obtained by dividing the power supply voltage Vcc is taken out. However, any of the first to fourth total resistance values may deviate from the design target resistance value due to an etching error when patterning using a microfabrication technique such as a photolithography technique. For this reason, when the magnetic field φ in the Y direction is not applied (φ = 0 [mT]), the output voltage Vout becomes a voltage V1 [V] higher than the design target value voltage Vd [V] (V1> Vd), when the voltage V2 [V] is lower than the design target voltage Vd [V] (V2 <Vd), the output voltage Vout may vary in the vertical direction. Along with this, the actual measurement curve obtained when the magnetic sensor 1 of the present invention and the magnetic sensor 11 of the comparative example are applied so that the intensity of the magnetic field φ in the Y direction is increased is upward from the target curve C0. Or it will shift downward. Note that an actual measurement curve C1 indicated by a broken line indicates a curve shifted to the maximum in the upward direction, and an actual measurement curve C2 indicates a curve shifted to the maximum in the downward direction.

  In both the magnetic sensor 1 of the present invention and the magnetic sensor 11 of the comparative example, when the strength ± φ0 [mT] of the magnetic field φ in the Y direction is set as the operating point (threshold) of the magnetic sensor in the design target curve C0, the magnetic field in the Y direction In a region where the output voltage Vout is equal to or lower than the voltage V0 [V], with the voltage V0 [V] when the constant voltage line S passing through the intensity ± φ0 [mT] of φ intersects the design target curve C0, Y A magnetic field φ in the direction is detected.

  However, in both the magnetic sensor 1 of the present invention and the magnetic sensor 11 of the comparative example, in the actual measurement curve C1, the output voltage Vout is higher than the voltage V0 [V] even when the magnetic field φ in the Y direction with an intensity ± φ0 [mT] is applied. Since the voltage Va [V] is large (Va> V0), the magnetic field φ in the Y direction is not detected. When the strength of the magnetic field φ in the Y direction is varied and reaches the strength ± φ1 [mT] (| ± φ1 | [mT]> | ± φ0 | [mT]), the output voltage Vout becomes the voltage V0 [V]. At this time, the magnetic field φ in the Y direction is detected. That is, in the actual measurement curve C1, the magnetic field φ in the Y direction shifted in the direction of increasing by (| ± φ1 | − | ± φ0 |) [mT] with respect to the intensity | ± φ0 | [mT] is detected.

  Further, in both the magnetic sensor 1 of the present invention and the magnetic sensor 11 of the comparative example, in the actual measurement curve C2, the output voltage Vout when the intensity ± φ0 [mT] is applied as the magnetic field φ in the Y direction is higher than the voltage V0 [V]. It is a small voltage Vb [V] (Vb <V0). The output voltage Vout becomes the voltage V0 [V] when the strength of the magnetic field φ in the Y direction ± φ2 [mT] (| ± φ2 | [mT] <| ± φ0 | [mT]). That is, in the actual measurement curve C2, the magnetic field φ in the Y direction shifted in the direction of decreasing by (| ± φ0 | − | ± φ2 |) [mT] with respect to the intensity | ± φ0 | [mT] is detected.

  Therefore, the magnetic field detected by the magnetic sensor is (| ± φ1 | to | ± φ2) due to the voltage variation width ((V1−V2) [V]) of the output voltage Vout when the magnetic field φ in the Y direction is not applied. |) It varied in the range of [mT] and was not constant.

  Specifically, for example, when 1 V is applied as the power supply voltage Vcc to the magnetic sensor 11 of the comparative example, the voltage variation width of the output voltage Vout when the magnetic field φ in the Y direction is not applied is 3.7 mV. On the other hand, for example, when 1 V is applied as the power supply voltage Vcc to the magnetic sensor 1 of the present invention, the voltage variation width of the output voltage Vout when the magnetic field φ in the Y direction is not applied was 1.9 mV. Therefore, the magnetic field in the Y direction in the magnetic sensor 1 of the present invention is obtained by separating the first wiring pattern 3A and the second wiring pattern 3B from each other without using one common wiring pattern. The voltage variation width of the output voltage Vout when φ was not applied could be reduced to almost half that of the magnetic sensor 11 of the comparative example. The above-described shapes of the wiring patterns 3A, 3B, etc. are merely examples. For example, even if the line width or line length is changed, the voltage variation width can be reduced to almost half. Even when the power supply voltage Vcc was changed and measured, the voltage variation width could be reduced to almost half.

  In general, the resistance value of a magnetoresistive element used for a magnetic sensor is as large as several kΩ, for example. On the other hand, the resistance value of the wiring pattern that electrically connects the magnetoresistive element and the electrode pad for taking out the output voltage has a short line length and is formed using a metal thin film. . For this reason, when a person skilled in the art designs a magnetic sensor, only consideration of the shape of the magnetoresistive element and how to reduce the size by devising the wiring pattern, the wiring pattern is completely considered. There wasn't. For this reason, from the viewpoint of ease of design and manufacture, the wiring pattern for electrically connecting the end portions of the first and second magnetoresistive elements R11 and R12 and the electrode pad 4 is made common. It was formed in a wiring pattern. In such a technical background, the inventor has earnestly expressed the superiority of separately forming the first wiring pattern 3A and the second wiring pattern 3B through experiments.

  Next, the reason why the variation width of the output voltage Vout is reduced in the magnetic sensor 1 of the present invention will be examined.

  When one common wiring pattern is used, the contact position of the probe electrically connected to the electrode pad 4 to extract the output voltage, the variation in the bonding position of the bonding wire, the pattern line width Due to the etching variation, the current path flowing inside one common wiring pattern changes. Along with this, a difference occurs in the resistance value of one common wiring pattern, and the ratio of contribution to the third total resistance value and the fourth total resistance value is different. On the other hand, in the magnetic sensor 1 of the present invention, since the first wiring pattern 3A and the second wiring pattern 3B are separated and formed without using one common wiring pattern, the contact position of the probe and Even if the bonding position of the bonding wire and the etching variation of the pattern line width occur, the current path flowing through the first wiring pattern 3A and the second wiring pattern 3B is substantially constant. For this reason, the ratio of the resistance value of the first wiring pattern 3A contributing to the first total resistance value is substantially constant, and the ratio of the resistance value of the second wiring pattern 3B contributing to the second total resistance value. Is almost constant. As a result, variations in the first total resistance value and the second total resistance value are reduced, and the output voltage Vout, which is a value obtained by dividing the power supply voltage Vcc by the first total resistance value and the second total resistance value, is reduced. The voltage variation width is reduced.

  The magnetic sensor 1 according to the first embodiment is configured to include the first magnetoresistive element R1 and the second magnetoresistive element R2. However, the present invention is not limited to this, and a plurality of series circuits are provided in which each one end side of the two magnetoresistive elements is connected to an electrode pad for taking out a voltage through each wiring pattern formed separately, It is good also as a structure which connects each other end side of each magnetoresistive element which comprises each series circuit in common via an electrode pad. At this time, the other end side of each magnetoresistive element constituting each series circuit and the electrode pad may be electrically connected via a wiring pattern formed separately, or one common It may be electrically connected via the formed wiring pattern. In addition, in the case of being electrically connected through one common wiring pattern, one common wiring is compared with the case of being electrically connected through a separate wiring pattern. Since the resistance value of the pattern varies, the voltage variation width of the output voltage Vout increases accordingly.

  Next, FIG. 4 shows a magnetic sensor 21 according to the second embodiment. A feature of the magnetic sensor 21 is that a full bridge circuit is configured using four magnetoresistive elements, and an electrode pad and a magnetoresistive element are electrically connected using a separately formed wiring pattern. is there. In the second embodiment, the same components as those in the first embodiment are denoted by the same reference numerals, and the description thereof is omitted.

  The magnetic sensor 21 includes a substrate 22 and four magnetoresistive elements R1 to R4. The substrate 22 extends, for example, along the X direction and the Y direction orthogonal to each other, and the magnetoresistive elements R1 to R4 are formed on the surface thereof.

  The first to fourth magnetoresistive elements R1 to R4 are formed in a meander shape by alternately connecting a long strip-shaped pattern and a short strip-shaped pattern. The extension direction of the long strip pattern in the first and third magnetoresistive elements R1 and R3 extends along the X direction, and the resistance value becomes the smallest when a detection magnetic field in the Y direction which is the first direction is given. On the other hand, the extension direction of the long strip pattern in the second and fourth magnetoresistive elements R2 and R4 extends along the Y direction, and the resistance value is the smallest when a detection magnetic field in the X direction which is the second direction is given. Become. The magnetoresistive elements R1 to R4 are patterned into a predetermined shape using a fine processing technique such as a photolithography technique after a permalloy or the like, which is a magnetoresistive material, is formed on the substrate 22, for example.

  One end of the first magnetoresistive element R1 is electrically connected to the first electrode pad 24 for taking out the output voltage V10 via the first wiring pattern 23A. One end side of the second magnetoresistive element R2 is electrically connected to the first electrode pad 24 via a second wiring pattern 23B formed separately in the vicinity of the first wiring pattern 23A. . The other end side of the second magnetoresistive element R2 is electrically connected to the second electrode pad 26 for applying the power supply voltage Vcc through the third wiring pattern 25A. One end side of the third magnetoresistive element R3 is electrically connected to the second electrode pad 26 via a fourth wiring pattern 25B formed separately in the vicinity of the third wiring pattern 25A. . The other end of the third magnetoresistive element R3 is electrically connected to the third electrode pad 28 for taking out the output voltage V20 via the fifth wiring pattern 27A. One end side of the fourth magnetoresistive element R4 is electrically connected to the third electrode pad 28 via a sixth wiring pattern 27B formed separately in the vicinity of the fifth wiring pattern 27A. . The other end side of the fourth magnetoresistive element R4 is electrically connected to the fourth electrode pad 30 connected to the ground via the seventh wiring pattern 29A. The other end side of the first magnetoresistive element R1 is electrically connected to the fourth electrode pad 30 via an eighth wiring pattern 29B formed separately in the vicinity of the seventh wiring pattern 29A. The The electrode pads 24, 26, 28, and 30 and the first to eighth wiring patterns 23A, 23B, 25A, 25B, 27A, 27B, 29A, and 29B are made of, for example, vacuum deposition or sputtering of a conductive metal material such as aluminum. Then, after film formation on the substrate 22 by CVD or the like, it is patterned into a predetermined shape using a fine processing technique such as a photolithography technique. Usually, the first to eighth wiring patterns 23A, 23B, 25A, 25B, 27A, 27B, 29A, and 29B are formed to have substantially the same dimensions, for example, the film thickness, the line width, and the line length, and are arranged adjacent to each other. Therefore, patterning errors due to microfabrication techniques are generated in the same way. For this reason, the difference in resistance value between the first to eighth wiring patterns 23A, 23B, 25A, 25B, 27A, 27B, 29A, and 29B is extremely small.

  The first and second magnetoresistive elements R1, R2 are connected in series via the first, second, third and eighth wiring patterns 23A, 23B, 25A, 29B and the electrode pads 24, 26, 30. A first series circuit (half-bridge circuit) 31 is formed. The third and fourth magnetoresistive elements R3, R4 are connected in series via the fourth to seventh wiring patterns 25B, 27A, 27B, 29A and the electrode pads 26, 28, 30 to form a second series. A circuit (half-bridge circuit) 32 is formed. The first series circuit (half-bridge circuit) 31 and the second series circuit (half-bridge circuit) 32 are connected in parallel via the electrode pad 30 and the electrode pad 26 to form a full bridge circuit 33.

  When the power supply voltage Vcc is applied between the electrode pad 30 and the electrode pad 26, the electrode pad 24 to the eighth wiring pattern 29B to the first magnetoresistive element R1 to the first wiring pattern 23A to the electrode are applied from the electrode pad 24. The first total resistance value corresponding to the path of the pad 24 and the first total resistance value corresponding to the path of the electrode pad 24 to the second wiring pattern 23B to the second magnetoresistive element R2 to the third wiring pattern 25A to the electrode pad 26. Based on the total resistance value of 2, an output voltage V10 obtained by dividing the power supply voltage Vcc is taken out. Similarly, from the electrode pad 28, the third total resistance value corresponding to the path from the electrode pad 26 to the fourth wiring pattern 25B to the third magnetoresistive element R3 to the fifth wiring pattern 27A to the electrode pad 28 is set. The power supply voltage Vcc is divided by the fourth total resistance value corresponding to the path from the electrode pad 28 to the sixth wiring pattern 27B to the fourth magnetoresistive element R4 to the seventh wiring pattern 29A to the electrode pad 30. The output voltage V20 is taken out.

  Next, the magnetic field detection operation of the magnetic sensor 21 will be described with reference to FIG.

  A magnetic field φ in the Y direction in the + (plus) direction is applied to the magnetic sensor 21. At this time, as the strength of the magnetic field φ increases, the resistance values of the first and third magnetoresistive elements R1, R3 decrease, but the resistance values of the second and fourth magnetoresistive elements R2, R4 almost change. do not do. Therefore, as the strength of the magnetic field φ in the Y direction in the + direction increases, the output voltage V10 extracted from the first electrode pad 24 decreases and the output voltage V20 of the third electrode pad 28 increases. In addition, when a magnetic field φ in the Y direction in the − (minus) direction, which is different from the + direction by 180 degrees, is applied, the output characteristics are the same as those in the magnetic field φ in the + direction Y direction. Note that the resistance values of the first to fourth magnetoresistive elements R1 to R4 are the values from the first electrode pad 24 when the magnetic field φ in the Y direction is not applied to the magnetic sensor 21 (φ = 0 [mT]). The output voltage V10 is set to be larger than the output voltage V20 from the third electrode pad 28. Therefore, when the intensity of the magnetic field φ in the Y direction is around 0 [mT], the output voltage V10 of the first electrode pad 24 is higher than the output voltage V20 of the third electrode pad 28. When the strength of the magnetic field φ in the Y direction increases to reach ± φ0 [mT], the output voltage V10 of the first electrode pad 24 and the output voltage V20 of the third electrode pad 28 cross and further increase. As a result, the magnitude of the output voltage V10 of the first electrode pad 24 and the output voltage V20 of the third electrode pad 28 are reversed. Accordingly, the magnetic sensor 21 detects the magnetic field φ in the Y direction using the magnetic field strength ± φ0 [mT] as the operating point of the magnetic sensor.

  The first to fourth magnetoresistive elements R1 to R4 and the electrode pads 24, 26, 28, 30 constituting the magnetic sensor 21 are separated from each other to form first to eighth wiring patterns 23A, 23B, 25A. , 25B, 27A, 27B, 29A, and 29B. For this reason, for the same reason described in the first embodiment, the first to eighth wiring patterns 23A, 23B, 25A, 25B, 27A, 27B, which contribute to the first to fourth total resistance values. The ratio of the resistance values 29A and 29B is substantially constant. As a result, also in the magnetic sensor 21, the same effect as the magnetic sensor 1 in the first embodiment can be obtained.

  In each of the above embodiments, by reducing the resistance value of each wiring pattern as much as possible, the ratio of contribution to the total resistance value corresponding to each path can be reduced, thereby further reducing the variation width of the output voltage. can do. For this reason, in order to reduce the resistance value, the line width of each wiring pattern is preferably as wide as possible, and the line length is preferably as short as possible.

  In each of the above embodiments, each wiring pattern is patterned substantially the same. However, if the resistance value of each wiring pattern can be clearly estimated and the ratio of contribution to the total resistance value corresponding to each path can be estimated. For example, they may have different shapes.

  In each of the above embodiments, the case where the magnetic field φ in the Y direction is detected has been described as an example. However, the magnetic field in the X direction may be detected. Moreover, although the case where the X direction where the resistance value of the magnetoresistive element changes to the maximum and the Y direction are orthogonal to each other is illustrated, it is not always necessary to be orthogonal, and two different directions may be used.

  In each of the above-described embodiments, the meandering element is exemplified as each magnetoresistive element. However, the present invention is not limited to this, and the magnetoresistive element may be configured by, for example, one linear pattern.

DESCRIPTION OF SYMBOLS 1,21 Magnetic sensor 2,22 Board | substrate 3A, 23A 1st wiring pattern 3B, 23B 2nd wiring pattern 4, 6, 8 Electrode pad 5,7 Wiring pattern 9 Series circuit (half bridge circuit)
24 1st electrode pad 25A 3rd wiring pattern 25B 4th wiring pattern 26 2nd electrode pad 27A 5th wiring pattern 27B 6th wiring pattern 28 3rd electrode pad 29A 7th wiring pattern 29B 2nd 8 wiring pattern 30 4th electrode pad 31 1st series circuit 32 2nd series circuit 33 Full bridge circuit R1 1st magnetoresistive element R2 2nd magnetoresistive element R3 3rd magnetoresistive element R4 4th Magnetoresistive element

Claims (3)

A first magnetoresistive element whose resistance value changes to a maximum with respect to an applied magnetic field in a first direction;
A second magnetoresistive element whose resistance value changes to a maximum with respect to an applied magnetic field in a second direction different from the first direction;
An electrode pad;
A first wiring pattern for electrically connecting the electrode pad and the first magnetoresistive element;
A second wiring pattern formed separately from the first wiring pattern and electrically connecting the electrode pad and the second magnetoresistive element;
A magnetic sensor having at least one series circuit in which the first magnetoresistive element and the second magnetoresistive element are connected in series;
The resistance value of the first wiring pattern is added to the resistance value of the first magnetoresistive element;
The magnetic sensor according to claim 1, wherein a resistance value of the second wiring pattern is added to a resistance value of the second magnetoresistive element. First and third magnetoresistive elements whose resistance values change to a maximum with respect to the applied magnetic field in the first direction;
Second and fourth magnetoresistive elements whose resistance values change to the maximum with respect to an applied magnetic field in a second direction different from the first direction;
First to fourth electrode pads;
A first wiring pattern that electrically connects the first electrode pad and one end of the first magnetoresistive element;
A second wiring pattern formed separately from the first wiring pattern and electrically connecting one end of the first electrode pad and the second magnetoresistive element;
A third wiring pattern for electrically connecting the second electrode pad and the other end of the second magnetoresistive element;
A fourth wiring pattern formed separately from the third wiring pattern and electrically connecting one end of the second electrode pad and the third magnetoresistive element;
A fifth wiring pattern for electrically connecting the third electrode pad and the other end of the third magnetoresistive element;
A sixth wiring pattern formed separately from the fifth wiring pattern and electrically connecting one end of the third electrode pad and the fourth magnetoresistive element;
A seventh wiring pattern for electrically connecting the fourth electrode pad and the other end of the fourth magnetoresistive element;
An eighth wiring pattern formed separately from the seventh wiring pattern and electrically connecting the fourth electrode pad and the other end of the first magnetoresistive element;
A first series circuit in which the first magnetoresistive element and the second magnetoresistive element are connected in series;
A magnetic sensor having a second series circuit in which the third magnetoresistive element and the fourth magnetoresistive element are connected in series;
Each resistance value of the first wiring pattern and the eighth wiring pattern is added to the resistance value of the first magnetoresistive element,
Each resistance value of the second wiring pattern and the third wiring pattern is added to the resistance value of the second magnetoresistive element,
The resistance values of the fourth wiring pattern and the fifth wiring pattern are added to the resistance value of the third magnetoresistive element,
The magnetic sensor according to claim 6, wherein each resistance value of the sixth wiring pattern and the seventh wiring pattern is added to a resistance value of the fourth magnetoresistive element.   The magnetic sensor according to claim 1, wherein the wiring patterns formed separately are formed in substantially the same shape.

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