JP6711560B2 - Method of manufacturing magnetic sensor - Google Patents

Description

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

The magnetic sensor is applied to a rotation angle sensor or the like that forms a bridge circuit with a plurality of magnetic resistance elements and detects the direction of an external magnetic field by the output of the bridge circuit. When high reliability is required, such as when the rotation angle sensor is mounted on a vehicle, it is becoming necessary to increase redundancy in preparation for a failure.

For example, Patent Document 1 discloses an invention of a "rotation angle sensor" for the purpose of improving redundancy. The rotation angle sensor outputs a detection signal according to the rotation angle of the rotation shaft, and the detection signal changes in a sine wave shape with respect to the rotation angle of the rotation shaft, and the first to fourth detections have different phases. The phase difference of each of the first to fourth detection signals is set to “0°<φ<180°” or “180°<φ<360°” when the value is φ. It is said that. With this configuration, when any one of the first to fourth detection signals becomes abnormal, the arctangent value can be calculated based on the remaining three normal detection signals. Therefore, the rotation angle of the rotation axis can be detected, and even if any one of the three detection signals becomes abnormal, the arctangent value can be calculated based on the remaining two normal detection signals. Since it is possible, the rotation angle of the rotation shaft can be detected, and the redundancy is further improved.

JP, 2013-257231, A

By providing the method described in Patent Document 1 or another magnetic sensor having the same function as a backup, a failure is promptly detected, the backup magnetic sensor is operated, and the entire function as the magnetic sensor is performed. Can be maintained as

However, when the magnetic sensor of the sub system for backup is the same element as the magnetic sensor of the main system, the reliability performance of the main system and the sub system is the same, and both the main and sub systems fail due to the same environmental load. There is a high possibility that it will end up.

An object of the present invention is to provide a magnetic sensor that exhibits high reliability as a whole even when an excessive environmental load is applied to the magnetic sensor and the main system sensor fails.

In order to solve the above-mentioned problems, in a first aspect of the present invention, a first magnetic sensor element and a second magnetic sensor element different in kind from the first magnetic sensor element are provided, and the first magnetic sensor element is provided. The measurement target spatial regions of the magnetic sensor element and the second magnetic sensor element are the same, and the performance of the first magnetic sensor element in the first characteristic is higher than that of the second magnetic sensor element, and is different from the first characteristic. The performance of the second magnetic sensor element in the second characteristic is higher than that of the first magnetic sensor element , and two bridge circuits configured by the first magnetic sensor element and two bridge circuits configured by the second magnetic sensor element are provided. from the bridge circuit, for the same external magnetic field, the two output is obtained independently by the outputs from the two bridge circuits constituted by the first magnetic sensor element, the rotation angle of the external magnetic field from -180 ° +180 The range of the rotation angle of the external magnetic field that can be calculated in the range of ° and that can be calculated only by the outputs from the two bridge circuits configured by the second magnetic sensor element is configured by the first magnetic sensor element. A magnetic sensor equal to the calculable range by the outputs from the two bridge circuits .

The first characteristic includes sensitivity (output), phase accuracy, waveform distortion (linearity), heat resistance, heat resistance in a magnetic field, electrostatic breakdown resistance, disturbance magnetic field resistance, disturbance noise resistance, ease of manufacture, and manufacturing cost. The second characteristic may be any characteristic selected from a characteristic group, and the second characteristic may be a characteristic other than the first characteristic selected from the characteristic group.

The first magnetic sensor element is selected from an element group consisting of a giant magnetoresistive effect element, an anisotropic magnetoresistive effect element, a tunnel magnetoresistive effect element, a Hall element, a magnetic impedance element, and an eddy current magnetism measuring element. Alternatively, the second magnetic sensor element may be a magnetic sensor using an element other than the element used in the first magnetic sensor element selected from the element group. In this case, the element used in the first magnetic sensor element is a giant magnetoresistive effect element or a tunnel magnetoresistive effect element, and the element used in the second magnetic sensor element is an anisotropic magnetoresistive effect element or a Hall element. Preferably.

The first magnetic sensor element is selected from an element group consisting of a giant magnetoresistive effect element, an anisotropic magnetoresistive effect element, a tunnel magnetoresistive effect element, a Hall element, a magnetic impedance element, and an eddy current magnetism measuring element. Alternatively, the second magnetic sensor element may be a magnetic sensor using an element other than the element used in the first magnetic sensor element selected from the element group. In this case, the element used in the first magnetic sensor element is a giant magnetoresistive effect element or a tunnel magnetoresistive effect element, and the element used in the second magnetic sensor element is an anisotropic magnetoresistive effect element or a Hall element. Preferably.

According to a second aspect of the present invention, there is provided the above-described method for manufacturing a magnetic sensor, which comprises a first step of forming a free layer included in a free magnetic layer of the first magnetic sensor element , and the second magnetic sensor element. And a second step similar to the first step for forming a ferromagnetic layer included in the magnetic sensor.

The first magnetic sensor element is a giant magnetoresistive effect element, the second magnetic sensor element is an anisotropic magnetoresistive effect element, and a large magnetoresistive effect element including a fixed magnetic layer, a nonmagnetic intermediate layer and a free layer. Forming a first laminated film for formation, patterning the first laminated film to form the giant magnetoresistive effect element, and forming the giant magnetoresistive effect element, the direction of the magnetic field to be applied is changed. Steps of changing and repeating, and a step of forming a second laminated film for forming an anisotropic magnetoresistive effect element including a ferromagnetic layer, and patterning the second laminated film to form the anisotropic magnetoresistive effect element And the step of forming the free layer included in the first laminated film and the step of forming the ferromagnetic layer included in the second laminated film utilize the same process sharing the apparatus. It may be a process. May bridge circuit is constituted by at least four of the giant magnetoresistive effect element formed by the repeating step, in this case, the bridge circuit giant magnetoresistive elements belonging to the same bridge in, successively in the repeating step It may be formed by.

Note that the above summary of the invention does not enumerate all necessary features of the present invention. Further, a sub-combination of these feature groups can also be an invention.

A magnetic sensor module using the magnetic sensor 100 is shown. 3 is a plan view of the magnetic sensor 100. FIG. 3 is a partial cross-sectional view of the magnetic sensor 100. FIG. 3 is a circuit diagram of the magnetic sensor 100. FIG. An example of the output of the magnetic sensor 100 is shown. An example of the output of the magnetic sensor 100 is shown. FIG. 6 is a plan view showing an example of a magnetic sensor 100 being manufactured. FIG. 6 is a plan view showing an example of a magnetic sensor 100 being manufactured. FIG. 6 is a plan view showing an example of a magnetic sensor 100 being manufactured. FIG. 6 is a plan view showing an example of a magnetic sensor 100 being manufactured. FIG. 6 is a plan view showing an example of a magnetic sensor 100 being manufactured. It is a top view showing the example of other magnetic sensors. An example of advantages and disadvantages of a magnetic sensor element that can be used in a magnetic sensor will be shown.

Hereinafter, the present invention will be described through embodiments of the invention, but the following embodiments do not limit the invention according to the claims. Moreover, not all combinations of the features described in the embodiments are essential to the solving means of the invention.

FIG. 1 shows a magnetic sensor module using the magnetic sensor 100. The magnetic sensor module 10 shown in FIG. 1 has an arithmetic processing unit 14 and an electronic component 16 such as a chip capacitor on a substrate 12, and has leads 18 for external connection. The substrate 12 is generally a lead frame made of copper, and is processed by pressing or etching to form a circuit, but details are omitted in this figure. Further, the magnetic sensor 100 is provided in the central portion of the substrate 12. The magnetic sensor module 10 is arranged, for example, in a rotating magnetic field or installed in a member that rotates in a fixed magnetic field, and detects the rotating state of the magnetic field. The rotating magnetic field or the like to be measured is almost the same as that of the entire magnetic sensor 100, and when the magnetic sensor 100 includes a plurality of magnetic sensor elements, it can be said that the measurement target spatial areas of the respective magnetic sensor elements are the same.

FIG. 2 is a plan view of the magnetic sensor 100, and FIG. 3 is a partial cross-sectional view of the magnetic sensor 100. The magnetic sensor 100 has a first magnetic sensor element 120 and a second magnetic sensor element 140 of a different type from the first magnetic sensor element 120. The measurement target spatial regions of the first magnetic sensor element 120 and the second magnetic sensor element 140 are the same as described above.

As the first magnetic sensor element 120 and the second magnetic sensor element 140, here, a giant magnetoresistive effect element (GMR: hereinafter sometimes simply referred to as “GMR element”) and an anisotropic magnetoresistive effect element (AMR: Hereinafter, they may be simply referred to as "AMR elements"). Each sensor element forming the first magnetic sensor element 120 and the second magnetic sensor element 140 is formed on a single substrate 110.

The first magnetic sensor element 120 has four types of GMR elements 120a to 120d having different magnetization directions of the pinned magnetic layers, and the second magnetic sensor element 140 has four types of AMRs arranged on the substrate 110 and having different angles. It has elements 140a-d. The GMR elements 120a to 120d and the AMR elements 140a to 140d are connected by a wiring 150 to form a bridge circuit.

As shown in FIG. 3, the first magnetic sensor element 120 includes a seed layer 122, a fixed magnetic layer 124, a nonmagnetic intermediate layer 126, a free magnetic layer 128, and a cap layer 130, and the second magnetic sensor element 140 includes: It has a seed layer 142, a ferromagnetic layer 144, and a cap layer 146. The pinned magnetic layer 124 has a Synthetic-Ferri-Pin structure and includes a first ferromagnetic layer 124a, a non-magnetic intermediate layer 124b, and a second ferromagnetic layer 124c. The free magnetic layer 128 has an enhancement layer 128a and a free layer 128b. The free layer 128b and the ferromagnetic layer 144 may be made of the same material.

The pinned magnetic layer 124 is a self-pinned pinned magnetic layer, and the white arrow in FIG. 2 and the drawings shown later indicates the magnetization direction of the pinned magnetic layer 124. The magnetization direction of the free magnetic layer 128 changes due to an external magnetic field, and the resistance value of the GMR element, which is the first magnetic sensor element 120, changes according to the angle between the magnetization direction of the fixed magnetic layer 124 and the magnetization direction of the free magnetic layer 128. To do. The AMR element that is the second magnetic sensor element 140 has an easy axis of uniaxial magnetic anisotropy in the longitudinal direction of the ferromagnetic layer 144 formed in a meander shape, and an external magnetic field is generated by combining the AMR elements having different arrangement directions. Detect.

FIG. 4 shows a circuit diagram of the magnetic sensor 100. Although FIG. 4 shows only the GMR element which is the first magnetic sensor element 120, the circuit of the AMR element which is the second magnetic sensor element 140 is also the same. Two bridge circuits are configured with eight GMR elements 120a to 120d having different magnetization directions of the pinned magnetic layers, and Out4-Out1 differential output output between the Out4 terminal and the Out1 terminal and between the Out3 terminal and the Out2 terminal. From the output Out3-Out2 differential output, the rotation angle of the external magnetic field can be calculated. FIG. 5 is an example of the output of the magnetic sensor 100 and shows the output of the bridge circuit of FIG. 4 with respect to the rotation angle when the horizontal right direction of the paper surface of FIG. 2 is used as a reference. If the arctangent is calculated from the Out4-Out1 differential output and the Out3-Out2 differential output, the angle of the external magnetic field can be known.

Similarly, for the AMR element that is the second magnetic sensor element 140, eight AMR elements 140a to 140d form two bridge circuits in the same manner as Out6−Out5 differential output that is output between the Out6 terminal and the Out5 terminal. , Out8 terminal and Out7 terminal, the rotation angle of the external magnetic field can be calculated from the Out8-Out7 differential output. FIG. 6 is an example of the output of the magnetic sensor 100, and shows the output from the bridge circuit similar to FIG. 4 with respect to the rotation angle when the horizontal right direction of the paper surface of FIG. 2 is used as a reference. The angle of the external magnetic field can be known by calculating the arc tangent from the Out6-Out5 differential output and the Out8-Out7 differential output.

As described above, in the magnetic sensor 100 of the present embodiment, two outputs can be independently obtained for the same external magnetic field from the first magnetic sensor element 120 and the second magnetic sensor element 140. As a result, the reliability of the magnetic sensor 100 is enhanced. Moreover, since the first magnetic sensor element 120 and the second magnetic sensor element 140 are of different types, the failure modes are different, and the risk of simultaneous failure is extremely small. Therefore, the reliability of the magnetic sensor 100 becomes higher.

7 to 11 are plan views showing an example of the manufacturing process of the magnetic sensor 100. As shown in FIG. 7, first, the GMR element 120a is formed in a state where a magnetic field is applied in the downward direction perpendicular to the paper surface. In the GMR element 120a, the seed layer 122, the pinned magnetic layer 124, the nonmagnetic intermediate layer 126, the free magnetic layer 128, and the cap layer 130 shown in FIG. 3 are formed by sputtering, for example, and after patterning a mask. It is patterned and formed by a method of etching or a method of lifting off a previously patterned mask.

Next, as shown in FIG. 8, the GMR element 120c is formed in the same manner as the GMR element 120a in a state where a magnetic field is applied vertically upward in the drawing. Further, as shown in FIG. 9, a GMR element 120b is formed in the same manner as the GMR elements 120a and 120c in a state where a magnetic field is applied in the horizontal right direction of the paper surface, and as shown in FIG. The GMR element 120d is formed in the same manner as the GMR elements 120a to 120c with a magnetic field applied.

As described above, the GMR elements 120a to 120d are formed by the process of changing the direction of the applied magnetic field and repeating, and the GMR elements 120a to 120d form a bridge circuit. In the bridge circuit, the GMR element 120a and the GMR element 120c belong to the same bridge, and the GMR element 120b and the GMR element 120d belong to another same bridge, but the GMR elements (GMR element 120a and GMR element 120a and the GMR element 120d belong to the same bridge. 120c, and the GMR element 120b and the GMR element 120d) can be continuously formed in the above-described repeating process. By continuously forming the GMR elements belonging to the same bridge, the magnetic characteristics can be made uniform and the variation in the sensor characteristics can be suppressed low.

Next, as shown in FIG. 11, AMR elements 140a to 140d are formed. The AMR elements 140a to 140d are formed by forming each layer of the seed layer 142, the ferromagnetic layer 144 and the cap layer 146 shown in FIG. 3 by, for example, a sputtering method, patterning a mask, and then etching, or by previously patterning. A mask is lifted off and patterned to form.

Here, the ferromagnetic layer 144 can be formed by using the same process as that of forming the free layer 128b of the free magnetic layer 128. As a result, the devices necessary for the process can be shared, and the manufacturing cost can be reduced.

Finally, the wiring 150 is formed, the pad region and the like are plated, and the protective film is provided on the region other than the pad region, whereby the magnetic sensor 100 shown in FIG. 2 can be manufactured.

According to the magnetic sensor 100 described above, it is possible to obtain a highly reliable magnetic sensor in which all of them do not fail in the same failure mode. For example, it is possible to provide a magnetic sensor that exhibits high reliability as a whole even when an excessive environmental load is applied to the magnetic sensor and the main system sensor fails. In addition, it is possible to reduce costs by sharing part of the manufacturing process.

In the above-described embodiment, the first magnetic sensor element 120 is a GMR element and the second magnetic sensor element 140 is an AMR element. However, as shown in FIG. 12, the second magnetic sensor element 210 is a Hall element. Can also be used. In addition, as a magnetic sensor element to be combined with the GMR element, a tunnel magnetoresistive effect element (TMR element), a magnetic impedance element (MI element), and an eddy current type magnetic measuring element can be mentioned. Further, as the first magnetic sensor element and the second magnetic sensor element, two magnetic sensor elements may be arbitrarily selected from the elements shown above. Furthermore, three or more types of magnetic sensor elements may be combined. In this case, the reliability can be further improved.

FIG. 13 shows an example of selectable magnetic sensor elements and shows the advantages and disadvantages of each magnetic sensor element. It is preferable to select those magnetic sensor elements that have a relationship of complementing each other's performance. That is, the performance of the first magnetic sensor element 120 in a certain characteristic (first characteristic) is higher than that of the second magnetic sensor element 140, and the performance of the second magnetic sensor element 140 in another characteristic (second characteristic) is the first. It is preferably higher than the magnetic sensor element 120. As the first characteristic and the second characteristic, sensitivity (output), phase accuracy, waveform distortion (linearity), heat resistance, heat resistance in a magnetic field, electrostatic breakdown resistance, disturbance magnetic field resistance, disturbance noise resistance, manufacturability and manufacturing The cost can be indicated.

Although the present invention has been described above using the embodiments, the technical scope of the present invention is not limited to the scope described in the above embodiments. It is apparent to those skilled in the art that various changes or improvements can be added to the above-described embodiment. It is apparent from the scope of the claims that the embodiments added with such changes or improvements can be included in the technical scope of the present invention.

10... Magnetic sensor module, 12... Board, 14... Arithmetic processing device, 16... Electronic component, 18... Lead, 100... Magnetic sensor, 110... Board, 120... First magnetic sensor element, 120a-d... GMR element, 122 ...Seed layer, 124... pinned magnetic layer, 124a... first ferromagnetic layer, 124b... non-magnetic intermediate layer, 124c... second ferromagnetic layer, 126... non-magnetic intermediate layer, 128... free magnetic layer, 128a... enhance layer , 128b... Free layer, 130... Cap layer, 140... Second magnetic sensor element, 140a-d... AMR element, 142... Seed layer, 144... Ferromagnetic layer, 146... Cap layer, 150... Wiring, 210... Second Magnetic sensor element

Claims (7)

A first magnetic sensor element and a second magnetic sensor element of a different type from the first magnetic sensor element,
The measurement target spatial regions of the first magnetic sensor element and the second magnetic sensor element are the same,
The performance of the first magnetic sensor element in the first characteristic is higher than that of the second magnetic sensor element,
The performance of the second magnetic sensor element in the second characteristic different from the first characteristic is higher than that of the first magnetic sensor element,
From the two bridge circuits composed of the first magnetic sensor element and the two bridge circuits composed of the second magnetic sensor element, two outputs are independently obtained for the same external magnetic field,
The rotation angle of the external magnetic field can be calculated in the range of −180° to +180° by the outputs from the two bridge circuits configured by the first magnetic sensor element,
The range of the rotation angle of the external magnetic field that can be calculated only by the outputs from the two bridge circuits configured by the second magnetic sensor element is the range from the two bridge circuits configured by the first magnetic sensor element. A method of manufacturing a magnetic sensor that is equal to the range that can be calculated from the output ,
A first step of forming a free layer included in the free magnetic layer of the first magnetic sensor element;
A method of manufacturing a magnetic sensor, comprising: forming a ferromagnetic layer included in the second magnetic sensor element; and a second step similar to the first step . The first characteristic consists of sensitivity (output), phase accuracy, waveform distortion (linearity), heat resistance, heat resistance in a magnetic field, electrostatic breakdown resistance, disturbance magnetic field resistance, disturbance noise resistance, manufacturability, and manufacturing cost. One of the characteristics selected from the characteristics group,
The method for manufacturing a magnetic sensor according to claim 1, wherein the second characteristic is a characteristic other than the first characteristic selected from the characteristic group. The first magnetic sensor element is selected from an element group consisting of a giant magnetoresistive effect element, an anisotropic magnetoresistive effect element, a tunnel magnetoresistive effect element, a Hall element, a magnetic impedance element, and an eddy current magnetism measuring element. Is a magnetic sensor using
The method of manufacturing a magnetic sensor according to claim 1, wherein the second magnetic sensor element is a magnetic sensor using an element other than the element used in the first magnetic sensor element selected from the element group. The element used in the first magnetic sensor element is a giant magnetoresistive effect element or a tunnel magnetoresistive effect element,
The method for manufacturing a magnetic sensor according to claim 3, wherein the element used in the second magnetic sensor element is an anisotropic magnetoresistive effect element or a Hall element. The method for manufacturing a magnetic sensor according to claim 1, wherein the first magnetic sensor element and the second magnetic sensor element are formed on a single substrate. The first magnetic sensor element is a giant magnetoresistive effect element, the second magnetic sensor element is an anisotropic magnetoresistive effect element,
Forming a first laminated film for forming a giant magnetoresistive effect element including a fixed magnetic layer, a non-magnetic intermediate layer and a free layer, and patterning the first laminated film to form the giant magnetoresistive effect element;
Changing the direction of the applied magnetic field and repeating the step of forming the giant magnetoresistive effect element;
Forming a second laminated film for forming an anisotropic magnetoresistive effect element including a ferromagnetic layer, and patterning the second laminated film to form the anisotropic magnetoresistive effect element,
The step of forming the free layer included in the first laminated film and the step of forming the ferromagnetic layer included in the second laminated film are steps using the same process sharing the apparatus.
The method for manufacturing a magnetic sensor according to claim 1 . A bridge circuit is formed by at least four giant magnetoresistive elements formed in the repeating step,
Giant magnetoresistive elements belonging to the same bridge in the bridge circuit are continuously formed in the repeating step.
The method for manufacturing the magnetic sensor according to claim 6 .

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