JP6506671B2 - Method of manufacturing magnetic sensor and method of manufacturing current sensor - Google Patents

Description

  The present invention relates to a method of manufacturing a magnetic sensor and a method of manufacturing a current sensor using the magnetic sensor.

  Patent Document 1 discloses a current sensor having a magnetic field detection bridge circuit including an output between two magnetoresistance effect elements, which includes four magnetoresistance effect elements whose resistance value is changed by application of an induction magnetic field from a current to be measured. The four magnetoresistance effect elements have the same rate of change in resistance, and antiferromagnetically couple the first ferromagnetic film and the second ferromagnetic film via the antiparallel coupling film. And the nonmagnetic intermediate layer, and the soft magnetic free layer, and the magnetization directions of the ferromagnetic fixed layers of the two magnetoresistance effect elements giving the output differ from each other by 180 °. A current sensor is disclosed, wherein the magnetic detection bridge circuit is a direction, and the wiring is symmetrical with respect to a power supply point.

  By providing the magnetic detection bridge circuit disclosed in Patent Document 1, a magnetic sensor having excellent linear response can be obtained, and by utilizing this characteristic, a current sensor with high measurement accuracy can be obtained.

JP 2014-81384 A

  As described above, when the linear response of the magnetic sensor becomes high, the offset value (output value in the state where no external magnetic field is applied) whose influence has been relatively small until now, the offset temperature characteristic (temperature dependence of offset) It may be required to further reduce the

  An object of the present invention is to provide a method of manufacturing a magnetic sensor having a small offset or offset temperature characteristic as described above, and a method of manufacturing a current sensor using such a magnetic sensor.

As a result of the present inventor's examination in order to solve the said subject, the following knowledge was acquired.
(A) One of the factors for increasing the offset and the offset temperature characteristic is variation at the manufacturing stage of the four magnetoresistive elements provided in the magnetic field detection bridge circuit.
(B) Variations in the manufacturing steps of the four magnetoresistive elements can be reduced by simultaneously manufacturing these magnetoresistive elements in a series of manufacturing processes.
(C) Even when they are manufactured simultaneously as such, application is performed by setting the four magnetoresistive elements to two pairs of magnetoresistive elements having different sensitivities (the rate of change in resistance to the external magnetic field). A magnetic field detection bridge circuit is obtained which has an output which responds linearly to the determined magnetic field.
(D) In order to simultaneously manufacture a pair of magnetoresistance effect elements having equal resistance values and different sensitivities, the aspect ratio (length of mean length of long pattern / length of long pattern of meander shape) But the widths of the long patterns may be different.

  The present invention completed based on the above findings is, in one aspect, composed of four magnetoresistance effect elements connected in series, each of which comprises four magnetoresistance effect elements whose resistance value changes according to the change of the external magnetic field. The method for manufacturing a magnetic sensor having a magnetic field detection bridge circuit including two partial circuits according to claim 1, wherein each of the four magnetoresistive elements has a meander shape in which a strip-shaped long pattern is folded back, The long pattern has a laminated structure having a ferromagnetic fixed layer, a nonmagnetic intermediate layer, and a soft magnetic free layer, and the four magnetoresistance effect elements have the entire length of the long pattern of the long pattern. The first magnetoresistance effect element and the second magnetoresistance effect element, which are two types of magnetoresistance effect elements having the same aspect ratio divided by the width but different widths of the long patterns, In one of the partial circuits of the magnetic field detection bridge circuit, the first magnetoresistance effect element and the second magnetoresistance effect element are connected in series in this order from the side closest to the power supply point, and the magnetic field detection In the other part of the partial circuit of the bridge circuit, the second magnetoresistance effect element and the first magnetoresistance effect element are connected in series in this order from the side proximal to the power supply point, and the four magnetoresistance effects are provided. A method of manufacturing a magnetic sensor, wherein an element is simultaneously formed by a series of film forming processes.

  As described above, with respect to the magnetoresistive effect element having a meander shape, by changing the width of the long pattern while making the aspect ratio common, it is possible to simultaneously manufacture two types of magnetoresistive effect elements having different sensitivities. As described above, in the above-described manufacturing method according to one aspect of the present invention, since the four magnetoresistive elements forming the magnetic field detection bridge are simultaneously manufactured, characteristic variations of these magnetoresistive elements do not easily occur. Therefore, variations in resistance value and temperature coefficient of resistance in the state where no magnetic field is applied from the outside are also less likely to occur, and as a result, a magnetic sensor having a small offset and offset temperature characteristics is easily obtained.

  The ferromagnetic pinned layer is a laminated ferrimagnetic material in which a first ferromagnetic film and a second ferromagnetic film in exchange coupling with an antiferromagnetic film are antiferromagnetically coupled via an antiparallel coupling film. It may be a type, or may be a self-pin type in which a first ferromagnetic film and a second ferromagnetic film are antiferromagnetically coupled via an antiparallel coupling film.

In the method of manufacturing a magnetic sensor as described above, the two magnetic flux sensors further include a feedback coil disposed in the vicinity of the four magnetoresistance effect elements and generating a cancellation magnetic field that cancels out the measured magnetic field, and the magnetic field detection bridge circuit includes the two When the feedback coil is energized by the voltage difference of the output provided between the two magnetoresistance effect elements included in each of the partial circuits, and when the magnetic field to be measured and the cancellation magnetic field are in an equilibrium state The measured magnetic field can be measured based on the current flowing through the feedback coil. By using the feedback coil in this manner, the measurement accuracy of the magnetic field to be measured can be enhanced.

  As described above, in the case of using a feedback coil, the feedback coil is arranged so as to be able to be applied so that the measured magnetic field and the cancellation magnetic field are along the direction orthogonal to the extending direction of the long pattern. The direction of application of the magnetic field can be a direction along the sensitivity axis direction of the magnetoresistive element. For this reason, it is preferable to arrange the feedback coil as described above from the viewpoint of enhancing the measurement accuracy of the measured magnetic field.

  By arranging the four magnetoresistive elements in parallel along the extending direction of the long pattern, it becomes easy to align the directions of the sensitivity axes of the four magnetoresistive elements. Therefore, as described above, the four magnetoresistive elements are preferably juxtaposed from the viewpoint of enhancing the measurement accuracy of the magnetic field to be measured.

  In another aspect, the present invention uses the magnetic sensor manufactured by the manufacturing method according to the above aspect of the present invention to flow in the direction along the longitudinal direction of the long pattern of the magnetoresistive element. A method of manufacturing a current sensor, comprising measuring an induced magnetic field generated by a current to be measured and quantitatively measuring the current to be measured. As described above, since the magnetic sensor manufactured by the manufacturing method according to one embodiment of the present invention has small offset and offset temperature characteristics, the induced magnetic field generated by the current to be measured is measured using this magnetic sensor. It is possible to quantitatively measure the measured current with high accuracy.

  According to the present invention, a method of manufacturing a magnetic sensor with small offset and offset temperature characteristics is provided. Also provided is a method of manufacturing a current sensor using such a magnetic sensor.

It is a figure showing an example of a magnetic balance type current sensor which uses a magnetic sensor manufactured by a manufacturing method concerning one embodiment of the present invention. It is a top view of one (1st magnetoresistive element) of two types of magnetoresistive elements with which the magnetic sensor manufactured by the manufacturing method concerning one embodiment of the present invention is provided. It is a top view of the other (the 2nd magnetoresistive effect element) of two kinds of magnetoresistive effect elements with which a magnetic sensor manufactured by a manufacturing method concerning one embodiment of the present invention is provided. It is a graph which shows the responsiveness with respect to the applied magnetic field of the element resistance of two types of magnetoresistive effect elements (GMR1, GMR2) manufactured by the manufacturing method which concerns on Example 1 of this invention. It is a graph which shows the responsiveness with respect to the applied magnetic field of the output voltage which consists of a middle point electric potential difference of the magnetic sensor manufactured by the manufacturing method which concerns on Example 1 of this invention. It is arrow sectional drawing in the II line shown in FIG. It is a figure which shows another example of the proportional type current sensor which uses the magnetic sensor manufactured by the manufacturing method which concerns on one Embodiment of this invention. It is sectional drawing which shows notionally the laminated structure of the magnetoresistive effect element manufactured by the manufacturing method which concerns on the comparative example 1 of this invention. It is a histogram regarding the offset value of the magnetic sensor manufactured by the manufacturing method concerning the example of the present invention. It is a histogram regarding the offset temperature characteristic of the magnetic sensor manufactured by the manufacturing method concerning the example of the present invention.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the attached drawings. The current sensor according to an embodiment of the present invention is a magnetic balance type current sensor including a magnetic balance type magnetic sensor.

  FIG. 1 is a diagram showing a magnetic balance type current sensor according to an embodiment of the present invention. In the present embodiment, the magnetic balance type current sensor shown in FIG. 1 is disposed in the vicinity of the conductor 11 through which the current to be measured flows. This magnetic balance type current sensor comprises a magnetic sensor 12 provided with a feedback circuit that generates a magnetic field (canceling magnetic field) B that cancels the induced magnetic field A due to the measured current flowing in the conductor 11. The feedback circuit includes a feedback coil 121 wound in a direction that cancels out the magnetic field generated by the linearly-measured current to be measured, and a magnetic field detection bridge circuit including four magnetoresistance effect elements 122a to 122d.

  The feedback coil 121 is configured by a planar coil. In this configuration, since the magnetic core is not provided, the feedback coil can be manufactured at low cost. Further, compared to the case of the toroidal coil, the cancellation magnetic field generated from the feedback coil can be prevented from spreading over a wide range, and the influence on the peripheral circuit can be avoided. Furthermore, compared to the case of the toroidal coil, when the current to be measured is alternating current, control of the cancellation magnetic field by the feedback coil is easy, and the current flowing for control does not become so large. These effects become greater as the measured current becomes higher with alternating current. When the feedback coil 121 is formed of a planar coil, it is preferable that a planar coil be provided so that both the induction magnetic field A and the cancel magnetic field B are generated in a plane parallel to the formation surface of the planar coil.

  The resistance value of the magnetoresistive effect elements 122a to 122d changes due to the application of the induction magnetic field A from the current to be measured. A magnetic field detection bridge circuit is configured by the four magnetoresistance effect elements 122a to 122d. By using the magnetic field detection bridge circuit having the magnetoresistance effect element as described above, a highly sensitive magnetic balanced current sensor can be realized.

  The magnetic field detection bridge circuit has two outputs that generate a voltage difference according to the induced magnetic field A generated by the current to be measured. In the magnetic field detection bridge circuit shown in FIG. 1, a power supply terminal Vdd, which is a power supply point, is connected to a connection point between the magnetoresistance effect element 122b and the magnetoresistance effect element 122c. One end of the resistive effect element 122d is connected to the ground (Gnd2, Gnd1). Furthermore, in this magnetic field detection bridge circuit, one output (Out1) is taken out from the connection point between the magnetoresistive effect element 122b and the magnetoresistive effect element 122d connected in series, and the magnetoresistive effect element connected in series One output (Out2) is taken out from the connection point between 122a and the magnetoresistance effect element 122c. The potential difference (Out1-Out2, midpoint potential difference) at these two outputs is amplified by the amplifier and is given to the feedback coil 121 as a current (feedback current). This feedback current corresponds to the midpoint voltage difference according to the induction magnetic field A. At this time, in the feedback coil 121, a cancellation magnetic field B that cancels out the induction magnetic field A is generated. Then, based on the current flowing through the feedback coil 121 when the induction magnetic field A and the cancellation magnetic field B are in an equilibrium state where they cancel each other, the induction magnetic field A is detected in the detection unit (specifically, a detection resistor may be used) The measured current is calculated based on the result of measurement.

  The magnetoresistance effect elements 122a to 122d included in the magnetic sensor 12 included in the current sensor according to the embodiment of the present invention are all disposed so that the longitudinal directions thereof are parallel to each other as shown in FIG. 2 and FIG. It is a GMR element having a shape (meander shape) in which a plurality of strip-like long patterns (stripes) SP are folded back. The plurality of long patterns SP are connected in series by the electrodes EL at both ends. In this meander shape, the sensitivity axis direction (Pin direction) is a width direction (stripe width direction) orthogonal to the longitudinal direction (stripe longitudinal direction) of the long pattern SP. In this meander shape, the induction magnetic field A and the cancellation magnetic field B are applied along the width direction (stripe width direction) of the long pattern SP.

  In this meander shape, the width in the direction of the pin (Pin) is preferably 1 μm to 10 μm from the viewpoint of enhancing the linear response. In this case, in consideration of linearity, it is desirable that the longitudinal direction be both perpendicular to the direction of the induction magnetic field A and the direction of the cancellation magnetic field B. With such a meander shape, the output of the magnetoresistive element can be obtained with the number of terminals (two terminals) smaller than that of the Hall element.

  The four magnetoresistive elements 122a to 122d included in the magnetic sensor 12 according to an embodiment of the present invention can output signals excellent in linear response to an applied magnetic field from the magnetic bridge circuit including these magnetoresistive elements. And the two magnetoresistive elements (a first magnetoresistive element GMR1 and a second magnetoresistive element GMR2) as described below so that they can be manufactured simultaneously by a series of film forming processes. It is done.

  The first magnetoresistance effect element GMR1, which is one of the two types of magnetoresistance effect elements, constitutes the magnetoresistance effect element 122c and the magnetoresistance effect element 122d as shown in FIG. It consists of elements. FIG. 2 is a plan view of the first magnetoresistance effect element GMR1.

  As shown in FIG. 1, the second magnetoresistive element GMR2, which is the other of the two magnetoresistive elements, constitutes the magnetoresistive element 122a and the magnetoresistive element 122b, and has relatively low sensitivity. It consists of elements. FIG. 2 is a plan view of the second magnetoresistance effect element GMR2.

  The sensitivity of the magnetoresistive element depends on the width W of the long pattern SP, and the basic tendency is that the wider the width W, the higher the sensitivity. When the width of the first magnetoresistance effect element GMR1 is compared with the width of the second magnetoresistance effect element GMR2, the width of the first magnetoresistance effect element GMR1 is wider. Therefore, the sensitivity of the first magnetoresistance effect element GMR1 is higher than that of the second magnetoresistance effect element GMR2.

Here, from the viewpoint of setting the two midpoint potential differences (Out1-Out2) of the magnetic field detection bridge circuit configured of the four magnetoresistive elements 122a to 122d to 0 V in the state where the magnetic field is not applied, The element resistance of the first magnetoresistive element GMR1 is preferably equal to the element resistance of the second magnetoresistive element GMR2. As described above, since the first magnetoresistance effect element GMR1 and the second magnetoresistance effect element GMR2 have different widths, the first magnetoresistance effect element GMR1 and the first magnetoresistance effect element GMR1 are required to meet the requirement for equalizing the element resistance. The total length of the long pattern SP is adjusted so that the aspect ratio described below of the second magnetoresistance effect element GMR2 becomes equal. In the present specification, the aspect ratio means a value obtained by dividing the total length Lt of the long pattern SP of the magnetoresistive element having a meander shape by the width W of the long pattern SP. The element resistance R of the magnetoresistive element is expressed by the following equation using the sheet resistance Rs, the total length Lt of the long pattern SP, and the width W of the long pattern SP.
R = Rs x Lt / W

  Therefore, in the case of the same material and the sheet resistance Rs being equal, the element resistance R becomes equal if the aspect ratio is equal. Therefore, by changing the width W of the long pattern SP while equalizing the aspect ratio, it is possible to simultaneously manufacture magnetoresistive elements having the same element resistance R and different sensitivities.

  The aspect ratio of the first magnetoresistance effect element GMR1 is 6 × L1 / W1 because the first magnetoresistance effect element GMR1 has six long patterns SP. On the other hand, the aspect ratio of the second magnetoresistance effect element GMR2 is 3 × L2 / W2 because the second magnetoresistance effect element GMR2 has three long patterns SP. Therefore, the shape of the long pattern SP is set such that the first magnetoresistive element GMR1 and the second magnetoresistive element GMR2 satisfy the relationship of 6 × L1 / W1 = 3 × L2 / W2.

  As the first magnetoresistance effect element GMR1 and the second magnetoresistance effect element GMR2 having such a relationship, magnetoresistance effect elements having the following shapes were produced on a trial basis.

First magnetoresistance effect element GMR1
Total length Lt of long pattern SP: 540 μm
(Length L1 in the longitudinal direction of the long pattern SP: 90 μm)
Width W1 of the long pattern SP: 3.0 μm
Aspect ratio: 180

Second magnetoresistance effect element GMR2
Total length Lt of long pattern SP: 144 μm
(Length L2 in the longitudinal direction of the long pattern SP: 48 μm)
Width W2 of the long pattern SP: 0.8 μm
Aspect ratio: 180

  The first magnetoresistance effect element GMR1 and the second magnetoresistance effect element GMR2 each have an element resistance of 2250 Ω when the external magnetic field is zero, and the response profile of the element resistance to the applied magnetic field is shown in FIG. It was as shown in 4. That is, the first magnetoresistance effect element GMR1 having a longer width W of the elongated pattern SP is higher in the applied magnetic field than the second magnetoresistance effect element GMR2 having a narrower width W of the elongated pattern SP. It was sensitivity.

  The first magnetoresistive element GMR1 and the second magnetoresistive element GMR2 are incorporated as shown in FIG. 1 to obtain a magnetic field detection bridge circuit. As shown in FIG. 1, in each of the first magnetoresistance effect element GMR1 and the second magnetoresistance effect element GMR2, the ferromagnetic pinned layer is oriented along the width direction of the elongated pattern SP (for example, in Y1 Y2 direction Y2 The soft magnetic free layer is magnetized so as to be oriented along the longitudinal direction of the long pattern SP (for example, in the X1 × 2 direction X2 direction) when no magnetic field is applied from the outside. The responsiveness to the applied magnetic field of the output voltage of the midpoint potential difference (Out1-Out2) of this magnetic field detection bridge circuit is as shown in FIG. Specifically, the response profile of the output voltage to the applied magnetic field also showed linearity in a range (a range of about ± 4 mT) which linearly responds to the applied magnetic field of the first magnetoresistance effect element GMR1.

  The layered structure (the magnetoresistive film) of the long patterns SP of the magnetoresistive effect elements 122a to 122d according to the embodiment of the present invention will be described with reference to FIG. The long pattern SP has a laminated structure provided on the substrate 29, as shown in FIG. The long pattern SP includes a seed layer 20, a laminated ferrimagnetic fixed layer 21 composed of an antiferromagnetic film 21a, a first ferromagnetic film 21b, an antiparallel coupling film 21c, and a second ferromagnetic film 21d. It includes a nonmagnetic intermediate layer 22, a soft magnetic free layer (free magnetic layer) 23, and a protective layer 25.

  The seed layer 20 is made of NiFeCr or Cr. In the above laminated structure, an underlayer formed of a nonmagnetic material such as at least one of Ta, Hf, Nb, Zr, Ti, Mo and W between the substrate 29 and the seed layer 20, for example. May be provided.

  In the ferromagnetic fixed layer 21, the antiferromagnetic film 21a and the first ferromagnetic film 21b are exchange coupled, and the first ferromagnetic film 21b and the second ferromagnetic film 21d are antiparallel coupling film 21c. Magnetization is fixed in one direction by coupling antiferromagnetically.

  Examples of the material constituting the antiferromagnetic film 21a include IrMn-based materials and PtMn-based materials. As a material which comprises the 1st ferromagnetic film 21b and the 2nd ferromagnetic film 21d, a CoFe alloy is illustrated by all. The antiparallel coupling film 21c located between the first ferromagnetic film 21b and the second ferromagnetic film 21d is made of Ru or the like.

  The nonmagnetic intermediate layer 22 is made of Cu or the like. The soft magnetic free layer (free magnetic layer) 23 is made of a magnetic material such as a CoFe alloy, a NiFe alloy, or a CoFeNi alloy. The protective layer 25 is made of Ta or the like.

  Seed layer 20, antiferromagnetic film 21a constituting the ferromagnetic fixed layer 21, first ferromagnetic film 21b, antiparallel coupling film 21c and second ferromagnetic film 21d, nonmagnetic intermediate layer 22, soft magnetic free layer The (free magnetic layer) 23 and the protective layer 25 are all formed by a method such as sputtering.

  Here, the antiferromagnetic film 21a and the ferromagnetic fixed layer 21 are formed of a magnetoresistive film (laminated structure forming a long pattern), and heat treatment is performed in a magnetic field after the film formation, thereby making the magnetization of the ferromagnetic fixed layer 21 strong. It can be fixed. In the method of manufacturing a magnetic sensor according to an embodiment of the present invention, the magnetoresistive effect elements 122a to 122d constituting the magnetic field detection bridge circuit are simultaneously manufactured by a series of film forming processes. Therefore, in each of the four magnetoresistance effect elements 122a to 122d, the ferromagnetic pinned layer 21 is magnetized in one direction (for example, in the Y1Y2 direction Y2 direction). In the four magnetoresistance effect elements 122a to 122d, the soft magnetic free layer (free magnetic layer) 23 is directed in one direction (for example, in the state where no magnetic field is applied from the outside due to the shape anisotropy associated with the meander shape) It is magnetized so as to be X1 × 2 direction X2 direction). As described above, the ferromagnetic pinned layer 21 and the soft magnetic free layer (free magnetic layer) 23 of the four magnetoresistive elements 122a to 122d are manufactured in a state in which the magnetization directions are uniform. Even if manufactured in this manner, the four magnetoresistance effect elements 122a to 122d are composed of two types of magnetoresistance effect elements GMR1 and GMR2 having equal element resistances and different sensitivities. It has been realized to have a linear response to the applied magnetic field.

  As described above, in the manufacturing method according to one embodiment of the present invention, since the magnetoresistive effect elements 122a to 122d are simultaneously formed in a series of film forming processes, the magnetoresistive effect elements 122a to 122d are respectively formed into different film forming processes. Variations in film thickness and composition are suppressed as compared with the case of forming by As a result, the characteristic variation of the four magnetoresistance effect elements 122a to 122d is suppressed. Therefore, the offset and offset temperature characteristics of the magnetic sensor 12 including the four magnetoresistance effect elements 122a to 122d become smaller, and the measurement accuracy of the current sensor using this magnetic sensor 12 becomes higher.

  The embodiments described above are described to facilitate the understanding of the present invention, and are not described to limit the present invention. Therefore, each element disclosed in the above embodiment is intended to include all design changes and equivalents that fall within the technical scope of the present invention.

  For example, as shown in FIG. 7, the magnetic sensor 12 'may not include a feedback coil, and the current sensor may be a magnetic proportional current sensor. The ferromagnetic pinned layer of the magnetoresistive film may be a self-pin type in which the magnetization can be pinned without using an antiferromagnetic material. The laminated ferrimagnetic ferromagnetic fixed layer using the antiferromagnetic film tends to have low heat resistance although it has high resistance to a strong magnetic field. On the other hand, the self-pinned ferromagnetic pinned layer tends to be low in resistance to a strong magnetic field but high in heat resistance, contrary to the laminated ferrimagnetic layer. Therefore, the type of the ferromagnetic fixed layer may be set according to the use environment of the magnetic sensor and the like.

  Hereinafter, the present invention will be more specifically described by way of examples and the like, but the scope of the present invention is not limited to these examples and the like.

Example 1
A plurality of magnetic sensors comprising the magnetic field detection bridge circuit and the feedback coil shown in FIG. 1 were manufactured on a substrate. The four magnetoresistance effect elements 122a to 122d included in the magnetic field detection bridge circuit each have a meander shape including a plurality of strip-like long patterns, and among these, relative to the two magnetoresistance effect elements 122c and 122d, The first magnetoresistance effect element GMR1 with high sensitivity is used. For the remaining two magnetoresistive elements 122a and 122b, the second magnetoresistive element GMR2 having a relatively low sensitivity is used. The first magnetoresistance effect element GMR1 and the second magnetoresistance effect element GMR2 have the following geometrical features.

First magnetoresistance effect element GMR1
Total length Lt of long pattern SP: 540 μm
(Length L1 in the longitudinal direction of the long pattern SP: 90 μm)
Width W1 of the long pattern SP: 3.0 μm
Aspect ratio: 180

Second magnetoresistance effect element GMR2
Total length Lt of long pattern SP: 144 μm
(Length L2 in the longitudinal direction of the long pattern SP: 48 μm)
Width W2 of the long pattern SP: 0.8 μm
Aspect ratio: 180

  The first magnetoresistance effect element GMR1 and the second magnetoresistance effect element GMR2 each have an element resistance of 2250 Ω when the external magnetic field is zero, and the response of the element resistance to the applied magnetic field is shown in FIG. It was. Further, the responsiveness of the output voltage of the midpoint potential difference (Out1-Out2) of the magnetic field detection bridge circuit to the applied magnetic field is as shown in FIG.

The first magnetoresistance effect element GMR1 and the second magnetoresistance effect element GMR2 are both seed layers from the bottom on the substrate having the insulating layer for the long pattern in the meander shape; NiFeCr (42) / ferromagnetic Fixed layer [antiferromagnetic layer; Ir ₂₂ Mn ₇₈ (60) / first ferromagnetic film; Co ₇₀ Fe ₃₀ (15) / antiparallel coupling film; Ru (8.5) / second ferromagnetic film; Co ₉₀ Fe ₁₀ (20)] / nonmagnetic interlayer; Cu (20) / soft magnetic free layer [Co ₉₀ Fe ₁₀ (10) / Ni _82.5 Fe _17.5 (70)] / protective layer; 100) was laminated by sputtering in the order of 100). The numerical values in parentheses indicate the layer thickness and the unit is Å.

  Four magnetoresistive elements were manufactured simultaneously. Heat treatment in a magnetic field after forming the magnetoresistive film causes strong exchange coupling between the antiferromagnetic layer and the ferromagnetic pinned layer, and the magnetization of the ferromagnetic pinned layer is magnetized in one direction. In addition, the soft magnetic free layer was magnetized in one longitudinal direction of the long pattern in the meander shape due to film formation in a magnetic field and shape anisotropy. Therefore, in the four magnetoresistance effect elements 122a to 122d, the magnetization directions of the ferromagnetic fixed layers are equal, and the magnetization directions of the soft magnetic free layer in the state where no external magnetic field is applied are equal.

300 or more were arbitrarily selected from a plurality of magnetic sensors manufactured on the substrate, and the offset value (the magnitude of the cancel current in the state where no magnetic field was applied from the outside (the same applies hereinafter), unit: mA) was measured . Further, the offset value OF1 (unit: mA) when the temperature is 85 ° C. and the offset value OF2 (unit: mA) when the temperature is 25 ° C. are measured, and the offset temperature characteristic OT (unit: μA / ° C) was measured.
OT = (OF 1 -OF 2) / (85 ° C-25 ° C)

  A histogram of the obtained offset value and offset temperature characteristic OT was determined. The results are shown in FIG. 9 and FIG.

(Comparative example 1)
A plurality of magnetic sensors comprising the magnetic field detection bridge circuit and the feedback coil shown in FIG. 1 were manufactured on a substrate. The four magnetoresistance effect elements 122a to 122d included in the magnetic field detection bridge circuit are each a meander shape having a plurality of strip-like long patterns, and the third magnetoresistance effect element having a shape characteristic common to the meander shapes. It consisted of GMR3. In the third magnetoresistance effect element GMR3, as shown in FIG. 8, the strip-shaped long pattern C-SP in the meander shape does not include the antiferromagnetic film 21a in the pinned magnetic layer 21 and is based on the RKKY interaction. It had a pinning structure.

Specifically, in the third magnetoresistive element GMR3, the long pattern C-SP in meander shape is formed on the substrate having the insulating layer from the bottom with the seed layer; NiFeCr (42) / ferromagnetic fixed layer 1 ferromagnetic film; Co ₄₀ Fe ₆₀ (19) / antiparallel coupling film; Ru (3.6) / second ferromagnetic film; Co ₉₀ Fe ₁₀ (24)] / nonmagnetic interlayer; Cu (20) Soft magnetic free layer [Co ₉₀ Fe ₁₀ (10) / Ni _82.5 Fe _17.5 (70)] / protective layer; Ta (100) stacked in this order by sputtering. The numerical values in parentheses indicate the layer thickness and the unit is Å.

  Four magnetoresistive elements were manufactured separately. The first ferromagnetic film was magnetized in one direction in the width direction of the long pattern C-SP in the meander shape by film formation in a magnetic field. Specifically, the magnetization direction (Y1Y2 direction Y1 direction) of the magnetoresistive effect element 122a is opposite to the magnetization direction (Y1Y2 direction Y2 direction) of the magnetoresistive effect element 122c connected in series thereto. The direction of magnetization of the magnetoresistive effect element 122b (in the Y1Y2 direction Y1 direction) was made opposite (in the Y1Y2 direction Y2 direction) to the direction of the magnetization of the magnetoresistive effect element 122d connected in series thereto. The direction of magnetization of the magnetoresistive element 122a was equal to the direction of magnetization of the magnetoresistive element 122b.

  The soft magnetic free layer was magnetized in one direction in the longitudinal direction of the long pattern in the meander shape by film formation in a magnetic field. Specifically, the magnetization direction (X1 X 2 direction X 1 direction) of the magnetoresistive effect element 122 a is made opposite (X 1 X 2 direction X 2 direction) to the magnetization direction of the magnetoresistive effect element 122 c connected in series thereto. The direction of the magnetization of the magnetoresistive effect element 122 b (in the X1 × 2 direction X1 direction) was made opposite (in the X1 × 2 direction X2 direction) to the direction of the magnetization of the magnetoresistive effect element 122 d connected in series. The direction of magnetization of the magnetoresistive element 122a was equal to the direction of magnetization of the magnetoresistive element 122b.

From the plurality of magnetic sensors formed on the substrate, 300 or more were arbitrarily selected and offset values (magnitude of cancellation current, unit: mA) were measured. Also, measure the offset value OF1 (size of cancellation current, unit: mA) when the temperature is 85 ° C and the offset value OF2 (size of cancellation current, unit: mA) when the temperature is 25 ° C. The offset temperature characteristic OT (unit: μA / ° C.) was measured by the following equation.
OT = (OF 1 -OF 2) / (85 ° C-25 ° C)

  A histogram of the obtained offset value and offset temperature characteristic OT was determined. The results are shown in FIG. 9 and FIG.

  As shown in FIG. 9 and FIG. 10, the magnetic sensor according to Example 1 has smaller offset value and offset temperature characteristics than the magnetic sensor according to Comparative Example 1, and the current obtained using the magnetic sensor according to Example 1 It was confirmed that the sensor can measure the current with higher accuracy than the current sensor formed by using the magnetic sensor according to Comparative Example 1.

11 Conductor 12, 12 'Magnetic sensor 121 Feedback coil 122a 122b 122c 122d Magnetoresistance effect element Vdd Power supply terminal Out 1 Magnetoresistance effect element 122b and Output Out2 from the connection point between the magnetoresistance effect element 122d: Output Gnd1 from the connection point between the magnetoresistance effect element 122a and the magnetoresistance effect element 122b: One end of the magnetoresistance effect element 122d Ground Gnd2 connected to the ground GMR1 connected to one end of the magnetoresistance effect element 122a first magnetoresistance effect element GMR2 second magnetoresistance effect element SP Long pattern C-SP: third magnetoresistive element GMR3 long pattern EL: electrode W1: first magnetoresistive element GM Width W2 of the long pattern SP of R1 ... Width of the long pattern SP of the second magnetoresistance effect element GMR2 ... Length of the long pattern SP of the first magnetoresistance effect element GMR1 L2: length in the longitudinal direction of the long pattern SP of the second magnetoresistance effect element GMR2 20: seed layer 21: ferromagnetic fixed layer 21a: antiferromagnetic film 21b: first 1 ferromagnetic film 21c ... antiparallel coupling film 21d ... second ferromagnetic film 22 ... nonmagnetic intermediate layer 23 ... soft magnetic free layer (free magnetic layer)
25 ・ ・ ・ Protective layer 29 ・ ・ ・ Substrate

Claims (7)

A magnetic sensor having a magnetic field detection bridge circuit which is composed of four magnetoresistance effect elements whose resistance value changes according to a change of an external magnetic field, and which includes two partial circuits consisting of two magnetoresistance effect elements connected in series. A manufacturing method,
Each of the four magnetoresistive elements is
The belt-like long pattern has a meander shape folded back,
The long pattern has a laminated structure having a ferromagnetic fixed layer, a nonmagnetic intermediate layer, and a soft magnetic free layer,
The four magnetoresistive elements are two types of magnetoresistive elements having a common aspect ratio obtained by dividing the total length of the long pattern by the width of the long pattern, but having different widths of the long pattern. A first magnetoresistive element and a second magnetoresistive element,
In one of the partial circuits of the magnetic field detection bridge circuit, the first magnetoresistance effect element and the second magnetoresistance effect element are connected in series in this order from the side proximal to the power supply point, and the magnetic field detection In the other of the partial circuits of the bridge circuit, the second magnetoresistance effect element and the first magnetoresistance effect element are connected in series in this order from the side proximal to the power supply point,
A method of manufacturing a magnetic sensor, wherein the four magnetoresistive elements are simultaneously formed by a series of film forming processes.   The ferromagnetic pinned layer is a laminated ferrimagnetic material in which a first ferromagnetic film and a second ferromagnetic film in exchange coupling with an antiferromagnetic film are antiferromagnetically coupled via an antiparallel coupling film. The method of manufacturing a magnetic sensor according to claim 1, which is a mold.   The magnetic pinned layer according to claim 1, wherein the ferromagnetic pinned layer is a self-pin type in which a first ferromagnetic film and a second ferromagnetic film are antiferromagnetically coupled via an antiparallel coupling film. Sensor manufacturing method. A feedback coil is disposed in the vicinity of the four magnetoresistive elements and generates a cancellation magnetic field that cancels out the measured magnetic field, and two of the two partial circuits included in each of the two partial circuits included in the magnetic field detection bridge circuit When the feedback coil is energized by the voltage difference of the output provided between the magnetoresistance effect elements, the current flowing through the feedback coil when in an equilibrium state where the measured magnetic field and the cancel magnetic field are canceled out The method of manufacturing a magnetic sensor according to any one of claims 1 to 3, wherein the measured magnetic field can be measured based on the detected magnetic field.   5. The method of manufacturing a magnetic sensor according to claim 4, wherein the feedback coil is disposed so as to be able to apply the measurement magnetic field and the cancellation magnetic field along a direction orthogonal to the extending direction of the long pattern.   The method for manufacturing a magnetic sensor according to any one of claims 1 to 5, wherein the four magnetoresistive elements are juxtaposed along the extending direction of the long pattern.   A magnetic sensor produced by the method according to any one of claims 1 to 6 is used to generate a current to be measured which flows in a direction along the longitudinal direction of the long pattern of the magnetoresistive element. And measuring the induced current quantitatively to measure the induced magnetic field.