JP2020191325A - Magnetic sensor and manufacturing method therefor - Google Patents

Abstract

To provide a top-pin magnetic sensor with suppressed offsets in output and the temperature characteristics of the output.SOLUTION: A magnetic sensor includes a plurality of magnetoresistive elements with different sensitivity axis directions, and in each of the magnetoresistive elements, on a substrate 11, a free magnetic layer 14, a non-magnetic material layer 15, and a fixed magnetic layer 16 are laminated from a substrate 11 side, and in the fixed magnetic layer 16, two magnetic layers 16a and a magnetic layer 16c laminated via a non-magnetic intermediate layer 16b are magnetized and fixed in antiparallel directions, and from among the two magnetic layers constituting the fixed magnetic layer 16, a magnetic layer 16a that is not in contact with the non-magnetic material layer 15 includes a second ferromagnetic material layer 16a3 that is in contact with the non-magnetic intermediate layer 16b, an intervening layer 16a2 provided on the second ferromagnetic material layer 16a3, and a first ferromagnetic material layer 16a1 provided on an intervening layer 16a2.SELECTED DRAWING: Figure 3

Description

The present invention relates to a magnetic sensor and a method for manufacturing the same.

In fields such as motor drive technology in electric vehicles and hybrid vehicles, relatively large currents are handled, so there is a demand for current sensors capable of measuring large currents in a non-contact manner. As such a current sensor, one using a magnetic sensor that detects an induced magnetic field from a measured current is known. Examples of the magnetic detection element for the magnetic sensor include a magnetoresistive element such as a GMR element and a TMR element.

The basic structure of the GMR element is a laminated structure in which a fixed magnetic layer and a free magnetic layer are laminated via a non-magnetic material layer. The fixed magnetic layer has an exchange coupling bias due to a laminated structure of an antiferromagnetic layer and a ferromagnetic layer, and an RKKY interaction (indirect exchange) due to a self-pinning structure in which two ferromagnetic layers are laminated via a non-magnetic intermediate layer. The magnetization direction is fixed in one direction by the interaction). The magnetization direction of the free magnetic layer can be changed according to the external magnetic field.

In a current sensor using a magnetic sensor provided with a GMR element, the magnetization direction of the free magnetic layer changes when an induced magnetic field from a measured current is applied to the GMR element. Since the electric resistance value of the GMR element fluctuates according to the relative angle between the magnetization direction of the free magnetic layer and the magnetization direction of the fixed magnetic layer, the magnetization direction of the free magnetic layer can be determined by measuring this electric resistance value. Can be detected. Then, based on the magnetization direction detected by the magnetic sensor, it is possible to obtain the magnitude and direction of the measured current to which the induced magnetic field is applied.

By the way, in an electric vehicle or a hybrid car, the drive of the motor may be controlled based on the current value, and the battery control method may be adjusted according to the current value flowing into the battery. Therefore, a current sensor using a magnetic sensor is required to improve the measurement accuracy of the magnetic sensor so that the current value can be detected more accurately.

As one method for improving the measurement accuracy of the magnetic sensor, as described in Patent Document 1, the magnetic sensor has a magnetic detection bridge circuit composed of a plurality of magnetic detection elements (magneto resistance effect elements in Patent Document 1). To prepare.

The magnetic sensor described in Patent Document 1 includes a plurality of magnetoresistive elements having different directions of sensitivity axes on the same substrate. In the magnetic sensor of Patent Document 1, after forming the first laminated film as a magnetoresistive element having a sensitivity axis in a specific direction, the first laminated film other than the region where the first laminated film remains is removed from the substrate. A second laminated film serving as a magnetoresistive sensor having a sensitivity axis in a direction different from a specific direction is formed.

WO2011 / 111649

Since the magnetic sensor described in Patent Document 1 forms magnetoresistive elements having different sensitivity axes, a laminating step is performed for each magnetoresistive element. Therefore, a layer thickness difference (film thickness difference) of the laminated body occurs due to an error in the laminating process, and this layer thickness difference causes an offset in the output from the magnetic detection bridge circuit and the temperature characteristics of the output.
Therefore, the present invention is a top pin type in which offsets in the output from the magnetic detection bridge circuit and the temperature characteristics of the output are suppressed by suppressing the difference in layer thickness of a plurality of magnetoresistive elements constituting the magnetic detection bridge circuit. It is an object of the present invention to provide a magnetic sensor.

The present invention provided to solve the above problems is, in one embodiment, a magnetic sensor including a plurality of magnetic resistance effect elements having different directions of sensitivity axes, and the magnetic resistance effect elements are each placed on a substrate. The fixed magnetic layer has a structure in which a free magnetic layer, a non-magnetic material layer, and a fixed magnetic layer are laminated from the substrate side, and the fixed magnetic layer has two magnetic layers laminated via a non-magnetic intermediate layer antiparallel. Of the two magnetic layers that are magnetized and fixed to the fixed magnetic layer, the magnetic layer that is not in contact with the non-magnetic material layer is the second ferromagnetic material layer that is in contact with the non-magnetic intermediate layer. The intervening layer provided on the second ferromagnetic material layer and the first ferromagnetic material layer provided on the intervening layer are provided.
The magnetoresistive sensor has a structure in which the magnetic layer farther from the substrate is sandwiched between the two magnetic layers constituting the fixed magnetic layer, and the first and second ferromagnetic material layers sandwich the intervening layer. Therefore, the direction of the sensitivity axis differs depending on the direction of application of the magnetic field when the free magnetic layer to the intervening layer are simultaneously formed by a plurality of magnetoresistive elements and the first ferromagnetic material layer is formed on the intervening layer. A magnetoresistive sensor can be formed.

In the magnetoresistive element in the magnetic sensor, the first ferromagnetic material layer and the second ferromagnetic material layer are magnetically coupled. The magnetic coupling of the first and second ferromagnetic material layers facilitates the formation of magnetoresistive elements with different directions of sensitivity axes on the same substrate.

In order to magnetically bond the first and second ferromagnetic material layers, the intervening layer shall be one or two selected from the group consisting of Pt and Pd, and the first ferromagnetic material. It is preferable that the magnetization amount and coercive force of the layer are equal to or larger than the magnetization amount and coercive force of the second ferromagnetic material layer, and the layer thickness of the intervening layer is 15 Å or less.

An antiferromagnetic layer may be laminated on the first ferromagnetic material layer. The antiferromagnetic coupling between the antiferromagnetic layer and the first ferromagnetic material layer stabilizes the magnetization of the fixed magnetic layer and improves the magnetic field resistance of the magnetic sensor.

Each of the magnetoresistive elements may have an antiferromagnetic layer on the substrate side of the free magnetic layer. The antiferromagnetic coupling between the antiferromagnetic layer and the free magnetic layer suppresses the magnetization dispersion of the free magnetic layer, making it difficult to create multiple magnetic domains, that is, a magnetic sensor having excellent resistance to strong magnetic fields.

In another aspect, the present invention is a method for manufacturing the magnetic sensor, wherein the free magnetic layer, the non-magnetic material layer, a magnetic layer in contact with the non-magnetic material layer, the non-magnetic intermediate layer, and a second. The ferromagnetic material layer and the intervening layer are simultaneously formed on the plurality of magnetic resistance effect elements having different sensitivity axis directions, and the magnetic resistance effect elements are individually formed for each direction of the sensitivity axis of the magnetic resistance effect element. This is a method for manufacturing a magnetic sensor, which forms a pattern and forms the first ferromagnetic material layer while applying a magnetic field in the direction of the sensitivity axis.
For the plurality of magnetoresistive sensors having different directions of sensitivity axes, the magnetic layer, the non-magnetic intermediate layer, the second ferromagnetic material layer, and the intervening layer can be simultaneously formed to make each layer the same thickness. it can. Therefore, it becomes a magnetic sensor in which the offset in the output and the temperature characteristics of the output is suppressed.

In another aspect, the present invention is a method for manufacturing the magnetic sensor having the anti-magnetic layer on the substrate side of the free magnetic layer, wherein the anti-magnetic layer, the free magnetic layer, and the non-magnetic material. The layer, the magnetic layer in contact with the non-magnetic material layer, the non-magnetic intermediate layer, the second ferromagnetic material layer, and the intervening layer are simultaneously formed on the plurality of magnetic resistance effect elements having different directions of the sensitivity axes. In order to apply a bias magnetic field to the free magnetic layer by the anti-ferrometric layer, annealing in a magnetic field is performed to form an individual pattern of the magnetic resistance effect element for each direction of the sensitivity axis of the magnetic resistance effect element. This is a method for manufacturing a magnetic sensor in which the first ferromagnetic material layer is formed while applying a magnetic field in the direction of the sensitivity axis.
By forming a first ferromagnetic material layer after annealing in a magnetic field to the laminated body formed at the same time, the magnetization dispersion or magnetization gradient of the fixed magnetic layer due to annealing in a magnetic field is suppressed, and the strength is strong. It has good magnetic field resistance and is a highly accurate magnetic sensor.

In the magnetic sensor of the present invention, a plurality of magnetoresistive elements can simultaneously form a film from the free magnetic layer to the intervening layer. Therefore, since it is possible to suppress the difference in layer thickness of a plurality of magnetoresistive elements constituting the magnetic detection bridge circuit, it is possible to provide a top-pin type magnetic sensor in which offsets in output and output temperature characteristics are suppressed. it can.

Top view conceptually showing the configuration of the magnetic sensor according to the first embodiment. Top view conceptually showing the structure of the magnetoresistive element The figure which shows typically the laminated structure in the BB arrow cross section cut by the broken line shown in FIG. (A)-(h) The figure explaining the manufacturing method of the magnetoresistive element (GMR element) which concerns on 1st Embodiment. (A)-(c) The figure which shows typically the laminated structure of the magnetoresistive element which concerns on 1st Embodiment. The figure which shows typically the laminated structure of the magnetic resistance effect element (TMR element) which concerns on 1st Embodiment. (A)-(c) The figure which shows typically the laminated structure of the magnetoresistive element which concerns on 2nd Embodiment. Graph showing the relationship between the layer thickness ratio of the ferromagnetic material and the MR ratio Graph showing the relationship between the applied magnetic field and ΔR / R in the magnetoresistive element (a) Comparative Example 1, (b) Example 4, (c) Example 5 Graph showing the relationship between the layer thickness of the intervening layer constituting the magnetic layer and the MR ratio Graph showing the relationship between the applied magnetic field and ΔR / R in the magnetoresistive element (a) Comparative Example 2, (b) Example 10, (c) Example 11 Graph showing the relationship between the layer thickness ratio of the ferromagnetic material and the MR ratio Graph showing the relationship between the applied magnetic field and ΔR / R in the magnetoresistive element (a) Comparative Example 3, (b) Example 16, (c) Example 17 Graph showing the relationship between the applied magnetic field and ΔR / R in the magnetic resistance effect element, annealing conditions (a) before forming the ferromagnetic material layer, in the magnetic field, (b) after forming all layers, in the magnetic field, (c) all layers After formation, in no magnetic field Graph showing the relationship between the applied magnetic field and ΔR / R in the magnetic resistance effect element, annealing conditions (a) before forming the ferromagnetic material layer, in the magnetic field, (b) after forming all layers, in the magnetic field, (c) all layers After formation, in no magnetic field

(First Embodiment)
Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.
FIG. 1 is a plan view conceptually showing the configuration of the magnetic sensor according to the present embodiment. As shown in the figure, the magnetic sensor 10 according to the embodiment of the present invention has a magnetic detection bridge circuit 10C provided with four magnetic detection units whose resistance values change in response to changes in an external magnetic field. ing.

Each magnetic detection unit is a part that detects magnetism and includes a magnetic measurement element composed of a magnetoresistive element. The four magnetic detection units are composed of two types of magnetic detection units (magneto resistive element 1, magnetoresistive element 2, hereinafter, when these are not distinguished, appropriately referred to as magnetoresistive sensor) having different directions of sensitivity axes. Will be done.

The magnetoresistive element 1 and the magnetoresistive element 2 have a common laminated structure, but the directions of the sensitivity axes are opposite to each other. The hollow arrow indicates the direction of magnetization of the fixed magnetic layer, that is, the direction of the sensitivity axis. Since the magnetic sensor 10 has a so-called one-chip configuration in which the magnetoresistive element 1 and the magnetoresistive element 2 are formed on the same substrate, it is advantageous for miniaturization.

In the magnetic detection bridge circuit 10C, a portion (series portion) in which the magnetoresistive element 1 and the magnetoresistive element 2 are connected in series is parallel between the power supply terminal Vdd and the ground terminal Gnd, which are power supply points. It is connected to the. In the two series portions connected in parallel, the magnetoresistive element 1 and the magnetoresistive element 2 are connected in a different order.

Outputs (Out1 and Out2) are provided between the magnetoresistive elements of each series portion connected in parallel. The potential difference between these two outputs (Out1-Out2, midpoint potential difference) is input to the amplifier Amp. The magnetic sensor 10 can quantitatively measure the magnitude of the magnetic field (external magnetic field) applied from the outside by the output (differential output) from the amplifier Amp.

FIG. 2 is a plan view conceptually showing the structure of the magnetoresistive sensor included in the magnetic sensor 10 according to the first embodiment. As shown in FIG. 2, the magnetoresistive element has a shape (minder shape) in which a plurality of long patterns (stripes) 3 arranged so that their longitudinal directions are parallel to each other are connected by a folded-back portion 4. .. By connecting the long pattern 3 at the folded-back portion 4, the entire long pattern 3 is electrically connected in series, and electrodes 4A are provided at both ends. The magnetoresistive sensor having the meander shape has a sensitivity axis direction (Pin direction) in the width direction orthogonal to the longitudinal direction of the long pattern 3, and measures an external magnetic field in the width direction.

FIG. 3 is a diagram schematically showing a laminated structure in a cross section taken along the line BB cut by the broken line shown in FIG. The magnetoresistive sensor included in the magnetic sensor 10 has a configuration in which a free magnetic layer 14, a non-magnetic material layer 15, and a fixed magnetic layer 16 are laminated on the substrate 11 from the substrate 11 side. The fixed magnetic layer 16 is a self-pinning layer based on the RKKY interaction in which two magnetic layers 16a and 16c laminated via a non-magnetic intermediate layer 16b are magnetized and fixed in antiparallel. The magnetoresistive sensor is a top pin type in which the fixed magnetic layer 16 is laminated at a position farther from the substrate 11 than the free magnetic layer 14.

FIG. 3 shows an example of the function or material of the layer constituting the magnetoresistive element for convenience of reference. In the present specification and drawings, an alloy of A and B, A _{Xat. %} B _{(100-X) at. %} Is described as XAB. For example, Fe _{60 at. %} Co _{40 at. %} -Is described as 60FeCo, and Co _{90 at. %} Fe _{10 at. %} Is described as 90CoFe.

The magnetization of the fixed magnetic layer 16 is fixed in one direction by the RKKY interaction between the magnetic layer 16a and the magnetic layer 16c arranged via the non-magnetic intermediate layer 16b.
The magnetic layers 16a and 16c are both ferromagnetic layers, and CoFe alloy is exemplified as a material constituting them. When the magnetic layers 16a and 16c are made of a CoFe alloy, it is preferable that the Fe content in the CoFe alloy constituting the magnetic layer 16a is higher than the Fe content in the CoFe alloy constituting the magnetic layer 16c. .. By doing so, the coercive force of the magnetic layer 16a becomes higher than the coercive force of the magnetic layer 16c, and the magnetic layer 16c is easily magnetized and fixed by the magnetic layer 16a magnetized during the film formation.

The non-magnetic intermediate layer 16b located between the magnetic layer 16a and the magnetic layer 16c is composed of Ru or the like. By setting the thickness of the non-magnetic intermediate layer 16b to 3 to 5 Å or 7 to 10 Å, the antiferromagnetic bond between the magnetic layer 16a and the magnetic layer 16c becomes stronger.

As shown in FIG. 3, the magnetoresistive sensor included in the magnetic sensor 10 includes a magnetic layer 16a that is not in contact with the non-magnetic material layer 15 among the two magnetic layers 16a and the magnetic layer 16c constituting the fixed magnetic layer 16. It has a laminated structure. Specifically, from the non-magnetic intermediate layer 16b side, a ferromagnetic material layer (second ferromagnetic material layer) 16a3 in contact with the non-magnetic intermediate layer 16b and an intervening layer 16a2 provided on the ferromagnetic material layer 16a3. It is a laminated structure with a ferromagnetic material layer (first ferromagnetic material layer) 16a1 provided on the intervening layer 16a2.

The specific configuration (composition, thickness, etc.) of the intervening layer 16a2 is not limited as long as the ferromagnetic material layer 16a1 and the ferromagnetic material layer 16a3 can be magnetically bonded via the intervening layer 16a2.

The ferromagnetic material layer 16a1 preferably has a magnetization amount (saturation magnetization Ms / layer thickness t) and a coercive force (Hc) of the ferromagnetic material layer 16a3 or more. As a result, after laminating the insulating layer 12, the seed layer 13, the free magnetic layer 14, the non-magnetic material layer 15, the magnetic layer 16a, the non-magnetic intermediate layer 16b, the ferromagnetic material layer 16a3, and the intervening layer 16a2 on the substrate 11. It is easy to form a magnetic resistance effect element in which the direction of the sensitivity axis is different for each region corresponding to the pattern depending on the direction of the magnetic field applied when laminating the ferromagnetic material layer 16a1 on the intervening layer 16a2 in a predetermined pattern. Can be done. The ferromagnetic material layer 16a1 and the ferromagnetic material layer 16a3 may be either a single layer or a multilayer.

The intervening layer 16a2 magnetically bonds the ferromagnetic material layer 16a1 and the ferromagnetic material layer 16a3 via the intervening layer 16a2, and contains one or two selected from the group consisting of Pt and Pd. Is preferable, and it is more preferable that it is composed of one or two of these. From the same viewpoint, the thickness of the intervening layer 16a2 is preferably 15 Å or less.

The intervening layer 16a2 also has a function of suppressing the oxidation of the ferromagnetic material layer 16a3 formed below the intervening layer 16a2 on the substrate 11 side. If the intervening layer 16a2 having a thickness of 3 Å or more is formed, the oxidation of the ferromagnetic material layer 16a3 can be stably suppressed.

The magnetization state of the self-pinning type fixed magnetic layer 16 is as shown in FIG. That is, the magnetization direction Sc of the magnetic layer 16c is to the right, and the ferromagnetic material layers 16a1 and 16a3 constituting the magnetic layer 16a in which the RKKY interaction with the magnetic layer 16c occurs via the non-magnetic intermediate layer 16b. The directions of magnetization of Sa1 and Sa3 are both leftward. From the viewpoint of strengthening the magnetization fixing force of the fixed magnetic layer 16 as much as possible, the difference in the amount of magnetization (saturation magnetization Ms / layer thickness t) between the magnetic layer 16a and the magnetic layer 16c is adjusted to be substantially zero. ing. The magnetization direction F of the free magnetic layer 14 is toward the back of the paper due to magnetic anisotropy based on shape anisotropy.

The non-magnetic material layer 15 is made of Cu or the like. The free magnetic layer 14 is made of a magnetic material such as a CoFe alloy, a NiFe alloy, or a CoFeNi alloy. The free magnetic layer 14 may have a single layer or a laminated structure composed of a plurality of films.

As shown in FIG. 3, the magnetoresistive element included in the magnetic sensor 10 may have the antiferromagnetic layer 17 laminated on the ferromagnetic material layer 16a1. By stacking the antiferromagnetic layers 17, the magnetization of the magnetic layer 16a is stabilized by the exchange bond, and the resistance to a strong magnetic field is improved. Examples of the antiferromagnetic layer 17 include IrMn and PtMn, but IrMn is preferable because Hex can be increased with respect to Hc. The antiferromagnetic layer 17 is protected by a protective layer 18 such as Ta.

(Production method)
A method capable of efficiently manufacturing the magnetic sensor 10 according to the present embodiment will be described below.
In the magnetic sensor 10 having a plurality of sensitivity axes (hereinafter referred to as multi-pin) on the same substrate, if even a slight difference in layer thickness occurs in the laminate constituting the magnetoresistive element, the output from the magnetic detection bridge circuit 10C and An offset occurs in the temperature characteristics. Conventionally, in a multi-pin magnetosensor 10 provided with magnetoresistive elements having different sensitivity axis directions, a magnetoresistive sensor having a sensitivity axis in a specific direction and another magnetoresistive sensor having different sensitivity axis directions are separated from each other. Since it is formed in the above direction, offsets are likely to occur in the output and temperature characteristics due to the layer thickness difference caused by the error in the manufacturing process.

Among the materials constituting the magnetoresistive sensor, the one having a large influence on the offset of the output from the magnetic detection bridge circuit 10C is adjacent to the non-magnetic material layer 15 and the non-magnetic material layer 15 having relatively small specific resistance. The free magnetic layer 14 and the magnetic layer 16c. Further, the layers having a large influence on the offset temperature characteristics are also the free magnetic layer 14 and the magnetic layer 16c adjacent to the non-magnetic material layer 15. This is because these include CoFe, NiFe, and the like, which are materials having a relatively large resistance temperature coefficient (TCR, Temperature Coefficient of Resistance), and have a high current density.

Therefore, the manufacturing method of the present embodiment makes the free magnetic layer 14, the non-magnetic material layer 15, the magnetic layer 16c in contact with the non-magnetic material layer 15, the non-magnetic intermediate layer 16b, the ferromagnetic material layer 16a3, and the intervening layer 16a2 sensitive. Simultaneous film formation is performed on magnetic resistance effect elements with different axial directions (simultaneous film formation step). Then, by forming an individual pattern and forming the ferromagnetic material layer 16a1 while applying a magnetic field in the sensitivity axis direction (individual film formation step), the magnetoresistive element 1 and the magnetoresistive effect having different sensitivity axis directions are formed. The element 2 is formed.

By simultaneously forming the layers constituting the magnetoresistive element having different directions of the sensitivity axes in this way, it is possible to prevent a layer thickness difference from occurring due to an error in the manufacturing process. The magnetic sensor 10 simultaneously forms a film on a portion of the laminated structure constituting the magnetoresistive sensor in which the free magnetic layer 14, the non-magnetic material layer 15 and the magnetic layer 16c are laminated. As a result, the magnetoresistive element 1 and the magnetoresistive element 2 having different directions of the sensitivity axes have the same layer thickness having a large influence on the offset. Therefore, the offset of the output and temperature characteristics from the magnetic detection bridge circuit 10C was suppressed. The magnetic sensor 10 has good measurement accuracy.

Further, by forming the above layers on the GMR1 and GMR2 at the same time, the offset of the output of the magnetic sensor 10 and the temperature characteristics of the offset can be reduced. Further, the offset of the output of the magnetic sensor 10 and the variation in the temperature characteristics of the offset between the wafers, the wafers, and the lots can be reduced.

4 (a) to 4 (h) are views for explaining the method for manufacturing the magnetoresistive element according to the present embodiment, and FIGS. 5 (a) to 5 (c) show the magnetoresistive element. It is a figure which shows the laminated structure schematically.
As shown in FIG. 4A, on the substrate 11, the insulating layer 12, the seed layer 13, the free magnetic layer 14, the non-magnetic material layer 15, the magnetic layer 16c, the non-magnetic intermediate layer 16b, the ferromagnetic material layer 16a3 and The intervening layers 16a2 are sequentially formed (simultaneous film formation step). The simultaneous film formation step is a step of "simultaneously" forming layers having a common function in magnetoresistive elements having different directions of sensitivity axes. FIG. 5A shows the laminated structure of the magnetoresistive element at this stage.

Next, as shown in FIG. 4B, the Al ₂ O ₃ protective layer 21 is formed on the intervening layer 16a _2, and then the resist layer 22 covering the Al ₂ O ₃ protective layer 21 is formed. By forming the Al ₂ O ₃ protective layer 21 on the intervening layer 16a2 before forming the resist layer 22, the residue of the organic substance used in photolithography has an adverse effect on the magnetoresistive element. Can be prevented.

The resist layer 22 is left in the region to be the magnetoresistive element 2 by photolithography to form a pattern of the resist layer 22. At this time, as shown in FIG. 4C, the Al ₂ O ₃ protective layer 21 is dissolved in the developing solution. As a result, the intervening layer 16a2 in the region where the magnetoresistive element 1 is provided can be exposed.

Next, as shown in FIG. 4 (d), the ferromagnetic material layer 16a1 is formed while applying a magnetic field in the direction of the stripe width direction (leftward toward the figure) of the meander shape indicated by the arrow, and then the ferromagnetic material layer 16a1 is formed. An antiferromagnetic layer 17 and a protective layer 18 are formed on the material layer 16a1. Then, as shown in FIG. 4 (e), the pattern of the resist layer 22 is removed. At this stage, the magnetoresistive element 1 is formed in a predetermined region. FIG. 5B shows the laminated structure of the magnetoresistive element at this stage.

In order to exchange and bond the magnetic layer 16a and the magnetic layer 16c, in this case, it is important to optimize the layer thickness of the non-magnetic intermediate layer 16b and to match Ms · t between the magnetic layer 16a and the magnetic layer 16c.

Next, as shown in FIG. 4 (f), the resist layer 22 is formed, and the resist layer 22 is left on the region of the magnetoresistive element 1 by photolithography to form the pattern of the resist layer 22. At this time, the Al ₂ O ₃ protective layer 21 on the region of the magnetoresistive element 2 is removed by dissolving in the developing solution.

Next, as shown in FIG. 4 (g), the ferromagnetic material layer 16a1 is formed while applying a magnetic field in the direction indicated by the arrow (right toward the figure), and then on the ferromagnetic material layer 16a1. The antiferromagnetic layer 17 and the protective layer 18 are formed. Next, as shown in FIG. 4 (h), the magnetoresistive element 1 and the magnetoresistive element 2 are formed in a predetermined region by removing the pattern of the resist layer 22 that covers the magnetoresistive element 1.

Next, the resist layer 22 covering the magnetoresistive sensor is formed, and the resist layer 22 is left in the region corresponding to the meander shape (see FIG. 2) of the magnetoresistive element by photolithography and etching to form the resist layer 22. Form a pattern. Then, after removing the exposed region by ion milling or the like, the pattern of the resist layer 22 is removed.

As shown in FIG. 5 (c), the ferromagnetic material layer 16a1 is formed in the region to be the magnetoresistive element 2 while applying a magnetic field in a direction different from that of the ferromagnetic material layer 16a1 of the magnetoresistive element 1. To. By magnetically coupling the formed ferromagnetic material layer 16a1 with the ferromagnetic material layer 16a3 via the intervening layer 16a2, the magnetization direction of the ferromagnetic material layer 16a3 can be changed.

As described above, the magnetoresistive element 1 and the magnetoresistive element 2 have the same film thickness as the layers from the insulating layer 12 to the intervening layer 16a2 being formed at the same time. By simultaneously forming a layer having a large influence on the offset of the output from the magnetic detection bridge circuit 10C and the temperature characteristics to have the same film thickness, the magnetic sensor 10 in which the offset is suppressed and the measurement accuracy is good. (See Fig. 1).

4 (a) to 4 (h) show two types of magnetoresistive elements having different sensitivity axes by 180 ° on the same substrate, but the types of magnetoresistive elements are not limited to two. .. For example, four types of magnetoresistive elements having different sensitivity axis directions of 90 °, 180 °, and 270 ° may be formed on the same substrate. In this case, the film formation of the ferromagnetic material layer 16a1 is repeated four times while applying a magnetic field in different directions for each magnetoresistive sensor having a different direction of the sensitivity axis.

In the above description, a giant magnetoresistive element (GMR element) is shown as an example of the magnetoresistive element, but a tunnel-type magnetoresistive element (TMR element) can also be used instead of the GMR element.
FIG. 6 is a diagram schematically showing a laminated structure of TMR elements. As shown in the figure, the TMR element includes a lower electrode 31 and an upper electrode 32. Further, the insulating barrier layer 35 is provided in place of the non-magnetic material layer 15 in the GMR element. Insulating barrier layer 35, MgO, _Al 2 _{O 3,} composed of titanium oxide.

(Second embodiment)
In this embodiment, the magnetoresistive sensor in which the antiferromagnetic layer is provided on the substrate side of the free magnetic layer in the magnetoresistive sensor will be described. In the manufacturing method of the present embodiment, an annealing treatment is performed in a magnetic field in order to apply a bias magnetic field to the free magnetic layer by exchange coupling with the antiferromagnetic layer to suppress the magnetization dispersion of the free magnetic layer. In this respect, it differs from the manufacturing method of the first embodiment described above. Hereinafter, members having the same function will be assigned the same number, and the differences from the first embodiment will be mainly described.

The manufacturing method of the present embodiment shows FIGS. 4 (a) to 4 (h) and FIGS. 5 (a) to 5 (c), except that annealing is performed in a magnetic field before forming the ferromagnetic material layer 16a1. It is the same as the manufacturing method in the first embodiment described with reference to it.
As shown in FIG. 7A, first, the antiferromagnetic layer 27, the free magnetic layer 14, the non-magnetic material layer 15, the magnetic layer 16c, the non-magnetic intermediate layer 16b, the ferromagnetic material layer 16a3 and the intervening layer 16a2 are formed. Simultaneously deposit magnetic resistance effect elements with different sensitivity axis directions. Next, the annealing process is performed while applying a magnetic field in the longitudinal direction of the meander-shaped stripe (see FIG. 2, toward the back toward FIG. 7A), and a bias magnetic field due to exchange coupling with the antiferromagnetic layer 27 is applied. It is applied to suppress the magnetization dispersion of the free magnetic layer 14.

As shown in FIGS. 7 (b) and 7 (c), in the magnetoresistive element of the present embodiment, the ferromagnetic material layer 16a1 is formed after annealing in a magnetic field. Therefore, the magnetization of the fixed magnetic layer 16 composed of the magnetic layer 16a, the non-magnetic intermediate layer 16b, and the magnetic layer 16c is dispersed or inclined by annealing in a magnetic field after the magnetoresistive sensor having different directions of the sensitivity axes is formed. There is nothing to do. Therefore, in the magnetic sensor 10 (see FIG. 1), the magnetization of the fixed magnetic layer 16 is strongly fixed in the direction of the sensitivity axis in a state where the dispersion is small, and the magnetic field resistance is good.

Hereinafter, the present invention will be described in more detail with reference to Examples and the like, but the scope of the present invention is not limited to these Examples and the like.

(Examples 1 to 6)
On the insulating layer 12 formed on the substrate 11, a common layer [seed layer 13 / free magnetic layer 14 / non-magnetic] common to a plurality of magnetoresistive elements having different sensitivity axis directions with the materials and layer thicknesses shown in Table 1 Material layer 15 / magnetic layer 16c / non-magnetic intermediate layer 16b / ferromagnetic material layer 16a3 / intervening layer 16a2] was formed.

As shown in FIG. 5B, the ferromagnetic material layer 16a3 in the common layer is magnetized in the same direction as the ferromagnetic material layer 16a1 in the magnetoresistive element 1 previously formed on the common layer. After that, as shown in FIG. 5C, the ferromagnetic material in the region to be the magnetic resistance effect element 2 is formed by forming the ferromagnetic material layer 16a1 while applying a magnetic field in a direction different from that of the magnetic resistance effect element 1. The layer 16a3 is magnetized in the same direction as the ferromagnetic material layer 16a1. In order to verify whether the magnetization direction of the self-pinning layer can be controlled by the magnetic field direction applied to the ferromagnetic material layer 16a1 on the common layer at the time of film formation, as shown in Table 1, in Examples 1 to 6. The direction of the magnetic field applied at the time of film formation was reversed between the ferromagnetic material layer 16a3 and the ferromagnetic material layer 16a1.

As shown in Table 1, the layer thickness of the intervening layer 16a2 constituting the magnetic layer 16a is fixed to 7.0 Å, and the total thickness of the ferromagnetic material layer 16a3 and the ferromagnetic material layer 16a1 is 20 Å. , A magnetoresistive sensor in which the layer thickness X of the ferromagnetic material layer 16a1 was changed to 18.0 Å, 15.0 Å, 12.5 Å, 10.0 Å, 7.0 Å or 4.0 Å was manufactured. In the magnetic field directions at the time of film formation shown in Table 1, Table 2, Table 4, Table 6, Table 7 and Table 9, ← indicates the negative magnetic field direction, and → indicates the positive magnetic field direction.

(Comparative Example 1)
The 60FeCo (20-X) / Pt (7.0) / 60FeCo (X) constituting the magnetic layer 16a (ferromagnetic material layer 16a3 / intervening layer 16a2 / ferromagnetic material layer 16a1) in Examples 1 to 6 are used. The magnetic resistance effect element of Comparative Example 1 having the configuration shown in Table 2 was manufactured by changing to 60FeCo (20.0) (the numbers in parentheses indicate the layer thickness (Å) of each layer).

After the magnetoresistive elements of Examples 1 to 6 and Comparative Example 1 obtained as described above were annealed at 290 ° C. for 3 hours, an external magnetic field was applied to obtain an MR ratio (ΔR / R, unit:%). Was measured. Table 3 and FIG. 8 show the relationship between the layer thickness ratio of the ferromagnetic material layer 16a1 (16a1 / (16a1 + 16a3)) and the MR ratio (ΔMR) with respect to the total thickness of the ferromagnetic material layers 16a1 and 16a3 of the magnetic layer 16a. Shown in.
9 (a), 9 (b) and 9 (c) show the magnetoresistive effect of Comparative Example 1, Example 4 (layer thickness ratio 0.50) and Example 5 (layer thickness ratio 0.35). It is a graph which shows the relationship between the applied magnetic field (external magnetic field) in an element, and ΔR / R.

The ratio (layer thickness ratio) of the layer thickness of the ferromagnetic material layer 16a1 to the total layer thickness of the ferromagnetic material layer 16a1 and the ferromagnetic material layer 16a3 shown in FIG. 9B is 0.50. The shape of the graph showing the relationship between the external magnetic field of the magnetic resistance effect element and ΔR / R became high resistance on the positive magnetic field side as in Comparative Example 1 shown in FIG. 9 (a). On the other hand, the graph of the magnetoresistive element having a layer thickness ratio of 0.35 shown in FIG. 9C shows a high resistance on the negative magnetic field side unlike Comparative Example 1 shown in FIG. 9A. From this result, it was found that if the layer thickness ratio is 0.50 or more, the magnetization direction of the self-pinning layer can be controlled in the magnetic field direction at the time of forming the ferromagnetic material layer 16a1.

In Examples 1 to 6, the ferromagnetic material layer 16a1 and the ferromagnetic material layer 16a3 were formed by using the same ferromagnetic material (60FeCo). However, both may be formed using different ferromagnetic materials. In this case, the ferromagnetic material layer 16a1 is a material and a layer thickness in which the amount of magnetization (= saturation magnetization Ms · layer thickness t) and coercive force (Hc) are larger than those of the ferromagnetic material layer 16a3.

(Examples 7 to 12)
On the insulating layer 12 formed on the substrate 11, a common layer [seed layer 13 / free magnetic layer 14 / non-magnetic] common to a plurality of magnetoresistive elements having different sensitivity axis directions with the materials and layer thicknesses shown in Table 4 Material layer 15 / magnetic layer 16c / non-magnetic intermediate layer 16b / ferromagnetic material layer 16a3 / intervening layer 16a2] was formed.

As shown in Table 4, the magnetoresistive elements of Examples 7 to 12 in which the layer thickness Y of the intervening layer 16a2, which constitutes the magnetic layer 16a, was changed were produced. Specifically, as shown in Table 5, the magnetoresistor in which the layer thickness Y of the intervening layer 16a2 is changed to 7.5 Å, 10.0 Å, 12.5 Å, 15.0 Å, 17.5 Å or 20.0 Å. Manufactured effect elements.

(Comparative Example 2)
60FeCo (7.5) / Pt (Y) / 60FeCo (12.5) in Examples 7 to 12 was changed to 60FeCo (20.0) to provide the same configuration as in Example 1 shown in Table 1. A magnetoresistive element was manufactured.

After annealing Examples 7 to 12 and Comparative Example 2 obtained as described above at 290 ° C. for 3 hours, an external magnetic field was applied and the MR ratio (ΔR / R, unit:%) was measured. The relationship between the layer thickness of the intervening layer 16a2 constituting the magnetic layer 16a and the MR ratio is shown in Table 5 and FIG.
11 (a), 11 (b) and 11 (c) show the magnetoresistive elements of Comparative Example 2, Example 10 (layer thickness 15.0 Å) and Example 11 (layer thickness 17.5 Å). It is a graph which shows the relationship between the applied magnetic field (external magnetic field) and ΔR / R.

As shown in FIGS. 11 (a) and 11 (b), the shape of the graph showing the relationship between the external magnetic field of the magnetoresistive element having a layer thickness of 15 Å and ΔR / R is a comparative example. Similarly to 1, the resistance became high on the positive magnetic field side. On the other hand, the graph of the magnetoresistive sensor having a layer thickness of 17.5 Å in the intervening layer 16a2 shown in FIG. 11C shows that the shape of the graph is reversed and the resistance becomes high on the negative magnetic field side, unlike Comparative Example 1. became. This result suggests that the ferromagnetic bond disappeared when the layer thickness of the intervening layer 16a2 was 17.5 Å or more. Therefore, if the layer thickness of the intervening layer 16a2 is 15 Å or less, a ferromagnetic bond of 60FeCo is generated via the intervening layer 16a2 made of Pt, and the ferromagnetic material layer 16a1 and the ferromagnetic material layer 16a3 are magnetically bonded. It can be said that.

(Examples 13 to 18)
On the insulating layer 12 formed on the substrate 11, a common layer [seed layer 13 / antiferromagnetic layer 27 / free] common to a plurality of magnetoresistive elements having different sensitivity axes with the materials and layer thicknesses shown in Table 1 Magnetic layer 14 / non-magnetic material layer 15 / magnetic layer 16c / non-magnetic intermediate layer 16b / ferromagnetic material layer 16a3 / intervening layer 16a2] was formed. Examples 13 to 18 differ from Examples 1 to 6 in that an antiferromagnetic layer 27 is provided between the seed layer 13 and the free magnetic layer 14.

As shown in Table 6, the layer thickness of the intervening layer 16a2 constituting the magnetic layer 16a is fixed to 7.0 Å, and the total thickness of the ferromagnetic material layer 16a3 and the ferromagnetic material layer 16a1 is 20 Å. , The layer thickness X of the ferromagnetic material layer 16a1 was changed to 18.0 Å, 15.0 Å, 12.5 Å, 10.0 Å, 7.0 Å or 4.0 Å to manufacture a magnetoresistive sensor.

(Comparative Example 3)
The 60FeCo (20-X) / Pt (7.0) / 60FeCo (X) constituting the magnetic layer 16a (ferromagnetic material layer 16a3 / intervening layer 16a2 / ferromagnetic material layer 16a1) in Examples 13 to 18 are used. Instead of 60FeCo (20.0), the magnetoresistive sensor of Comparative Example 3 having the configuration shown in Table 7 was manufactured (the numbers in parentheses indicate the layer thickness (Å) of each layer).

After the magnetoresistive elements of Examples 13 to 18 and Comparative Example 3 obtained as described above were annealed at 290 ° C. for 3 hours, an external magnetic field was applied to obtain an MR ratio (ΔR / R, unit:%). Was measured. Tables 8 and 12 show the relationship between the layer thickness ratio (16a1 / (16a1 + 16a3)) of the ferromagnetic material layer 16a1 in the ferromagnetic material layers 16a1 and 16a3 constituting the magnetic layer 16a and the MR ratio.
13 (a), 13 (b) and 13 (c) show the magnetoresistive effect of Comparative Example 3, Example 16 (layer thickness ratio 0.50) and Example 17 (layer thickness ratio 0.35). It is a graph which shows the relationship between the applied magnetic field (external magnetic field) in an element, and ΔR / R.

As shown in Table 8 and FIGS. 13 (a) to 13 (c), the magnetism of Examples 13 to 18 and Comparative Example 3 in which the antiferromagnetic layer 27 is provided between the seed layer 13 and the free magnetic layer 14. The resistance effect element showed the same results as in Examples 1 to 6 and Comparative Example 1.

(Example 15)
For the magnetoresistive sensor of Example 15 having the configuration shown in Table 9, the annealing conditions (implementation timing and magnetic field) performed to suppress the magnetization dispersion of the free magnetic layer 14 by exchange coupling with the antiferromagnetic layer 27. The relationship between the applied magnetic field and ΔR / R was measured by changing the presence / absence).

14 (a) to 14 (c) and 15 (a) to 15 (c) are measurement results after annealing the magnetoresistive element under the following conditions.
(A) After forming the common layer and before forming the ferromagnetic material layer 16a1, anneal (b) all layers in a magnetic field (100 mT) and then anneal (c) all layers in a magnetic field (100 mT). After forming, anneal in no magnetic field

Both the magnetoresistive sensor of FIGS. 14 (a) and 14 (b) annealed in a magnetic field have a higher hysteresis suppressing effect than the magnetoresistive sensor of FIG. 14 (c) annealed in a magnetic field. Indicated. It is considered that this is because the magnetization dispersion of the free magnetic layer 14 was suppressed by the exchange bond with the antiferromagnetic layer 27. Further, the graph shapes of FIGS. 14 (a) and 14 (b) were substantially the same. From this, it can be said that the effect of annealing in the magnetic field performed before forming the ferromagnetic material layer 16a1 is not reduced by the magnetic field applied when forming the ferromagnetic material layer 16a1 thereafter.

Further, as shown in FIG. 15A, by performing annealing in a magnetic field before forming the ferromagnetic material layer 16a1, a plateau region is formed in a graph showing the relationship between the applied magnetic field and ΔR / R. It was. This indicates that the magnetization dispersion or magnetization gradient of the fixed magnetic layer constituting the magnetoresistive sensor is small, and the strong magnetic field resistance is high. The degree of magnetization dispersion of the fixed magnetic layer can be evaluated by the plateau magnetic field (Hp (+), Hp (−)) in the plateau region. Here, the "plateau magnetic field" is the magnitude of the magnetic field at which the magnetization reversal of the magnetization fixed layer starts, and the magnitude of the magnetic field in which Ms · t of the fixed magnetic layer fluctuates by 2% (saturation magnetization per unit area, free). It is defined by (at the end of magnetic layer magnetization reversal).

As shown in FIG. 15B, when all layers were formed and then annealed in a magnetic field, a plateau region was not formed in the graph showing the relationship between the applied magnetic field and ΔR / R. On the other hand, as shown in FIG. 15 (c), when all layers are formed and then annealed in a magnetic field, a plateau region is formed. From this, due to annealing in a magnetic field, the magnetization dispersion or magnetization gradient between the magnetic layer 16a, the non-magnetic intermediate layer 16b, and the magnetic layer 16c of the fixed magnetic layer 16 forming the self-pinning layer becomes large, and the magnetization becomes high. It can be said that the magnetic field resistance has decreased.

After forming the common layer and before forming the ferromagnetic material layer 16a1, by annealing in a magnetic field (100 mT), a high hysteresis suppressing effect (see FIG. 14 (a)) and good strong magnetic field resistance (FIG. 15 (a)) can be stably realized.

The magnetic sensor of the present invention can be used as a current sensor or the like for obtaining the magnitude and direction of a measured current to which an induced magnetic field is applied based on the detected magnetization direction.

1, 2: Magnetic resistance effect element 3: Long pattern 4: Folded part 4A: Electrode 10: Magnetic sensor 10C: Magnetic detection bridge circuit 11: Substrate 12: Insulation layer 13: Seed layer 14: Free magnetic layer 15: Non-magnetic Material layer 16: Fixed magnetic layer 16a: Magnetic layer 16a1, 16a3: ferromagnetic material layer 16a2: Intervening layer 16b: Non-magnetic intermediate layer 16c: Magnetic layer 17, 27: Anti-ferrous layer 18: Protective layer 21: Al ₂ O ₃ Protective layer 22: Resist layer 31: Lower electrode 32: Upper electrode 35: Insulation barrier layer Gnd: Ground terminal Vdd: Power supply terminal Out1, Out2: Output Amp: Amplifier Sc, Sa1, Sa3: Direction of magnetization

Claims (9)

A magnetic sensor containing a plurality of magnetoresistive elements having different directions of sensitivity axes.
Each of the magnetoresistive effect elements has a configuration in which a free magnetic layer, a non-magnetic material layer, and a fixed magnetic layer are laminated on the substrate from the substrate side.
In the fixed magnetic layer, two magnetic layers laminated via a non-magnetic intermediate layer are magnetized and fixed in antiparallel.
Of the two magnetic layers constituting the fixed magnetic layer, the magnetic layer not in contact with the non-magnetic material layer is the second ferromagnetic material layer in contact with the non-magnetic intermediate layer and the second ferromagnetism. A magnetic sensor including an intervening layer provided on the material layer and a first ferromagnetic material layer provided on the intervening layer. The first ferromagnetic material layer and the second ferromagnetic material layer are magnetically coupled.
The magnetic sensor according to claim 1. The intervening layer is one or two selected from the group consisting of Pt and Pd.
The magnetic sensor according to claim 1. The magnetization amount and coercive force of the first ferromagnetic material layer are equal to or larger than the magnetization amount and coercive force of the second ferromagnetic material layer.
The magnetic sensor according to claim 1. The thickness of the intervening layer is 15 Å or less.
The magnetic sensor according to claim 1. An antiferromagnetic layer is laminated on the first ferromagnetic material layer.
The magnetic sensor according to claim 1. Each of the plurality of magnetoresistive elements has an antiferromagnetic layer on the substrate side of the free magnetic layer.
The magnetic sensor according to claim 1. The method for manufacturing a magnetic sensor according to claim 1.
The free magnetic layer, the non-magnetic material layer, the magnetic layer in contact with the non-magnetic material layer, the non-magnetic intermediate layer, the second ferromagnetic material layer, and the intervening layer are made of the plurality of magnetics having different sensitivity axis directions. The resistance effect element is formed at the same time,
An individual pattern of the magnetoresistive element is formed for each direction of the sensitivity axis of the magnetoresistive element.
A method for manufacturing a magnetic sensor, which forms a film of the first ferromagnetic material layer while applying a magnetic field in the direction of the sensitivity axis. The method for manufacturing a magnetic sensor according to claim 7.
The antiferromagnetic layer, the free magnetic layer, the non-magnetic material layer, the magnetic layer in contact with the non-magnetic material layer, the non-magnetic intermediate layer, the second ferromagnetic material layer and the intervening layer are formed on the sensitivity axis. The plurality of magnetic resistance effect elements having different directions are simultaneously deposited.
Annealing in a magnetic field is performed by the antiferromagnetic layer in order to apply a bias magnetic field to the free magnetic layer.
An individual pattern of the magnetoresistive element is formed for each direction of the sensitivity axis of the magnetoresistive element.
A method for manufacturing a magnetic sensor, which forms a film of the first ferromagnetic material layer while applying a magnetic field in the direction of the sensitivity axis.

Images