JP2004333217A - Magnetic field detector - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a magnetic field detector that can be miniaturized and can reduce power consumption, can control characteristic impedance, and has improved high-frequency characteristics in the magnetic field detector utilizing an impedance change. <P>SOLUTION: The magnetic field detector for utilizing an impedance change by an external magnetic field by directly energizing a high frequency to a magnetic body comprises a magnetic impedance element 3, and a conductive magnet thin film 5 connected to the magnetic impedance element 3, thus allowing the magnet thin film 5 to have the function of an electric circuit simultaneously with the application of a bias magnetic field. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a magnetic field detection device, and more particularly to a magnetic field detection device having a combined bias application structure using a magnet thin film.
[0002]
[Prior art]
2. Description of the Related Art With the rapid development of information devices and measurement / control devices in recent years, there has been an increasing demand for magnetic sensors that are small, low-cost, have high sensitivity and high response speed. For example, in a hard disk drive which is an external storage device of a computer, the performance has been improved from a bulk type inductive magnetic head to a thin film magnetic head and a magnetoresistive (MR) head.
[0003]
However, a rotary encoder, which is a rotation sensor of a motor, has a large number of magnetic poles of a magnet ring, and a magnetic sensor capable of detecting a weaker surface magnetic flux with high sensitivity is required instead of a conventional magnetoresistive effect (MR) sensor. It has become to. In addition, demand for a high-sensitivity magnetic sensor that can be used for nondestructive inspection, banknote inspection, and biomagnetic field measurement is increasing.
[0004]
Under such circumstances, various small and highly sensitive magnetic sensors have been developed.
[0005]
Typical magnetic detecting elements currently used include an inductive reproducing magnetic head, a magnetoresistive (MR) element, a flux gate sensor, and a Hall element. Recently, a high-sensitivity magnetic sensor using the magneto-impedance effect of an amorphous wire (Patent Documents 1, 2, or 3 below) has been proposed, and a high-sensitivity magnetic sensor using a magnetic impedance effect of a magnetic thin film ( Patent Literature 4 and Non-Patent Literature 1) have also been proposed.
[0006]
Among these magnetic sensors, a magnetic sensor using a magnetoresistive effect (MR) element and a magnetic impedance effect is a highly sensitive magnetic sensor that can be molded into an IC chip to form one chip. is there. However, these magnetic sensors cannot secure an operating point of the sensor unless a DC magnetic field called a bias magnetic field is applied to the sensor element in advance.
[0007]
As a method of applying the bias magnetic field, a method of generating a bias magnetic field by passing a current through a conductor such as a coil, a method of generating a bias magnetic field by combining magnets, and a method of generating a bias magnetic field using exchange coupling are equivalent to the bias magnetic field. Methods for producing the effect are known.
[0008]
Among the methods of combining magnets, as a method using a magnet film or a magnet layer, a magnetic field is generated in a direction at an angle of 45 ° from each element with respect to parallel MR elements whose magnetic field detection directions are different by 90 °. A method of applying a bias magnetic field with a single magnetic film (see Patent Document 5 below), in which a magnetic field is generated in a direction at an angle of 45 ° from each element with respect to parallel magneto-impedance elements having different magnetic field detection directions by 90 ° A method of applying a bias magnetic field with a single magnetic film (see Patent Document 6 below), a method of arranging a magnet layer on at least one of the upper, lower, left, and right sides of a magnetic field detecting element (see Patent Document 7 below), There is a method of applying a bias magnetic field by arranging one magnet layer at a time so as to be in contact with both ends of a magnetic impedance element of this book (see Patent Document 8 below).
[0009]
Further, as a method of applying a bias magnetic field by using a bulk magnet or a sheet magnet, there is a structure in which a magnetic field is laminated on a magnetic impedance sensor (see Patent Documents 9 and 10 below) and the like.
[0010]
[Patent Document 1]
JP-A-6-176930 [Patent Document 2]
JP-A-7-181239 [Patent Document 3]
JP-A-7-333305 [Patent Document 4]
JP-A-8-75835 [Patent Document 5]
Japanese Patent No. 2923959 [Patent Document 6]
JP 2001-305201 A [Patent Document 7]
Japanese Patent Application Laid-Open No. 2000-206127 [Patent Document 8]
JP 2000-162295 A [Patent Document 9]
Japanese Patent Application Laid-Open No. 2002-43649 [Patent Document 10]
Japanese Patent Application Laid-Open No. 2002-55148 [Non-Patent Document 1]
Journal of the Japan Society of Applied Magnetics, vol. 20,553 (1996)
[0011]
[Problems to be solved by the invention]
The present invention has a problem that occurs when a structure in which a bias magnetic field is applied using a magnet thin film is adopted for a magnetic field detection device requiring a bias magnetic field, that is, an electrode structure for supplying a sensor drive current and an arrangement of the magnet thin film. The problem that the device structure becomes complicated, the device size becomes large, and the problem of high-frequency characteristic impedance control that becomes difficult to control due to the complicated device structure due to the interference generated at the time of I do.
[0012]
That is, in view of the above-described circumstances, the present invention can achieve downsizing and low power consumption in a magnetic field detection device using an impedance change, control of characteristic impedance, and excellent high-frequency characteristics. It is an object to provide a magnetic field detection device.
[0013]
[Means for Solving the Problems]
The present invention, in order to achieve the above object,
[1] A magnetic field detection device that uses a change in impedance due to an external magnetic field by applying a high frequency directly to a magnetic body, comprising: a magnetic impedance element; and a conductive magnet thin film connected to the magnetic impedance element. It is characterized in that an electric circuit function is provided simultaneously with the application of a bias magnetic field.
[0014]
[2] The magnetic field detecting device according to [1], wherein the magnet thin film is used as a part of a conductive path in an element driving circuit.
[0015]
[3] The magnetic field detection device according to the above [1], wherein high frequency characteristics are improved by controlling a characteristic impedance between the magnetic impedance element and the magnet thin film.
[0016]
[4] The magnetic field detecting device according to the above [1], wherein the magnet thin film is arranged on one of the left and right sides of the magneto-impedance element.
[0017]
[5] The magnetic field detecting device according to [1], wherein the magnet thin film is used as a ground electrode of a slot line to form a high-frequency transmission line.
[0018]
[6] The magnetic field detection device according to [1], wherein the magnet thin film is disposed on the left and right sides of the magnetic impedance element, and the magnet thin film is used as a ground electrode of a coplanar line to form a high-frequency transmission line. I do.
[0019]
[7] The magnetic field detecting device according to the above [1], wherein the magnet thin film is arranged below the magnetic impedance element via an insulating film.
[0020]
[8] The magnetic field detection device according to the above [1], characterized in that an insulating structure is introduced and a magnetic thin film that is electrically divided is used.
[0021]
[9] The magnetic field detecting device according to the above [1], wherein the magnet thin film is disposed above and below the magnetic impedance element via an insulating film, and the magnet thin film is used as an electrode.
[0022]
[10] The magnetic field detection device according to the above [1], wherein the magnet thin film is used as a current-carrying electrode of a magnetic field detection element.
[0023]
[11] The magnetic field detector according to the above [10], wherein an electrode material is laminated on the magnet thin film.
[0024]
[12] The magnetic field detection device according to [1], further comprising two magnet thin films formed in a substantially semi-elliptical shape around the magneto-impedance element.
[0025]
[13] In the magnetic field detecting device according to any one of [1] to [12] above, as the magnet thin, which comprises using the SmCo ₅ alloy.
[0026]
According to the present invention, a high-frequency current is applied to a magnetic body, and in a magnetic field detection device using an impedance change according to an external magnetic field, a bias magnetic field that must be applied to a sensor in advance is applied with a small magnet thin film, By using the magnet thin film also as an electric circuit, miniaturization of the element and reduction in power consumption are realized.
[0027]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described in detail.
[0028]
FIG. 1 is a schematic view of a magnetic field detecting device according to a first embodiment of the present invention, which has a structure in which a magnet thin film is disposed on one of the right and left sides of a magnetic field detecting unit with respect to a magnetic field detecting direction.
[0029]
In this figure, 1 is a substrate, 2, 4, and 6 are electrode pads, 3 is a magnetic field detecting unit (magnetic impedance element), 5 is a magnet thin film, 7 is a magnet magnetization direction, 8 is a high-frequency current flowing direction, and 9 is a magnetic field. The detection direction is shown.
[0030]
Here, the magnet thin film 5 disposed on one of the left and right sides of the magnetic field detection unit 3 with respect to the magnetic field detection direction 9 is used as a conductive path.
[0031]
FIG. 2 is a schematic view of a magnetic field detecting device having a structure in which a high-frequency transmission line is formed using a magnet thin film as a ground electrode of a slot line according to a second embodiment of the present invention.
[0032]
In this figure, 11 is a substrate, 12, 14, 15, and 17 are electrode pads, 13 is a magnetic field detecting section (magnetic impedance element), 16 is a magnet thin film, 18 is a magnet magnetization direction, 19 is a high-frequency current flow direction, 20 Indicates a magnetic field detection direction.
[0033]
As described above, the high-frequency transmission line is formed by using the magnet thin film 16 as the ground electrode of the slot line.
[0034]
FIG. 3 is a schematic view of a magnetic field detection device according to a third embodiment of the present invention, which has a structure in which magnet thin films are disposed on both the left and right sides of a magnetic field detection unit with respect to a magnetic field detection direction.
[0035]
In this figure, 21 is a substrate, 22, 24, 25, 27, 28, and 30 are electrode pads, 23 is a magnetic field detecting section (magnetic impedance element), 26 and 29 are magnet thin films, 31 is a magnetization direction of a magnet, and 32 is a magnet. The high-frequency current flowing direction and 33 indicate the magnetic field detection direction.
[0036]
Here, the magnet thin films 26 and 29 are used as ground electrodes of a coplanar line to form a high-frequency transmission line.
[0037]
FIG. 4 is a schematic view of a magnetic field detection device according to a fourth embodiment of the present invention, which has a structure in which a magnet thin film is disposed below a magnetic field detection unit with respect to a magnetic field detection direction via an insulating film.
[0038]
In this figure, 41 is a substrate, 42 and 44 are electrode pads, 43 is a magnetic field detector (magnetic impedance element), 45 is a magnet thin film, 46 is an insulating film, 47 is a magnet magnetization direction, 48 is a high-frequency current flow direction, Reference numeral 49 denotes a magnetic field detection direction.
[0039]
Here, the magnet thin film 45 is disposed below the magnetic field detection unit 43 with respect to the magnetic field detection direction 49 via the insulating film 46. The magnet thin film 45 is used as a conductive path. Further, by controlling the dielectric constant and the film thickness of the insulating film 46, it is possible to control the characteristic impedance.
[0040]
FIG. 5 is a schematic view of a magnetic field detecting device according to a fifth embodiment of the present invention, which has a structure in which magnet thin films are disposed both above and below a magnetic field detecting unit with respect to a magnetic field detecting direction.
[0041]
In this figure, 51 is a substrate, 52 is a magnetic field detection unit (magnetic impedance element), 53 is an insulating film, 54 and 55 are magnet thin films, 56 is a magnet magnetization direction, and 57 is a magnetic field detection direction.
[0042]
Here, the high-frequency transmission lines are formed by using the magnet thin films 54 and 55 as ground electrodes of the strip line.
[0043]
FIG. 6 is a schematic diagram of a magnetic field detecting device according to a sixth embodiment of the present invention, which has a structure in which a magnetic field detecting unit is arranged inside a hole formed in a magnet thin film.
[0044]
In this figure, 61 is a substrate, 62 and 64 are connection electrodes, 65 and 67 are electrode pads, 63 is a magnetic field detection unit (magnetic impedance element), 66 and 68 are magnet thin films, 69 is a magnet magnetization direction, and 70 is a magnetic field. The detection direction is shown.
[0045]
Here, by making the shape of the holes formed in the magnet thin films 66 and 68 substantially semi-elliptical, the applied bias magnetic field can be made uniform. Here, the magnet thin films 66 and 68 are used as conductive paths. Thus, the insulating structure such as the slit introduced for electrically separating the magnet thin films 66 and 68 is also included in the scope of the claims.
[0046]
As described above, a bias magnetic field is applied to a magnetic field detecting element requiring a bias magnetic field by using a conductive magnet thin film, and at the same time, the magnet thin film is used as a part of an electric circuit, so that the element structure is improved. Simplify. Further, it is possible to provide a structure in which the characteristic impedance can be easily controlled for a high frequency driven magnetic sensor.
[0047]
Specifically, the magnet thin film is disposed on one or both sides of the magnetic field detection unit with respect to the magnetic field detection direction. Alternatively, a magnet thin film is arranged on one of the upper and lower sides of the magnetic field detection unit or on both the upper and lower sides. Furthermore, in a magneto-impedance element in which a magnet thin film is arranged so as to surround the magnetic field detecting portion in a ring shape, the conductive magnet thin film can be used as an electrode structure to simplify the element structure or be used as a surface mounting pad. By doing so, the simplification and miniaturization of the element structure are realized. Further, the geometrical arrangement of the magnetic field detection unit and the magnet thin film is controlled to realize characteristic impedance control.
[0048]
Hereinafter, more specific examples will be described.
[0049]
(Example 1)
FIG. 7 is a diagram showing the layout and element structure of the magnetic field detecting element and the magnet thin film according to the first embodiment of the present invention. In this embodiment, a magnetic field detection device having a coplanar structure in which magnet thin films are arranged on both left and right sides of a magnetic field detection element will be described.
[0050]
In this figure, 71 is a magnetic field detecting element (magnetic impedance element), 72 is a connection line, 73 and 74 are magnet thin films (composition SmCo ₅ ), and 75, 76 and 77 are electrode pads. The dimensions of each part are also displayed.
[0051]
The magnetic material composition of the magnetic field detecting element 71 is Co ₈₅ Nb ₁₂ Zr ₃ , and was formed on a glass substrate by RF sputtering (Ar atmosphere). The device dimensions were 2 mm in length, 20 μm in width, and 2.1 μm in film thickness, and were patterned using a lift-off method or an ion milling method. The magnetic film was subjected to a heat treatment in a magnetic field after film formation to impart magnetic anisotropy. The heat treatment conditions in a magnetic field include a heat treatment in a rotating magnetic field (40 kA / m, 400 ° C., 2 hours) and a heat treatment in a static magnetic field (40 kA / m, 400 ° C., 1 hour). The composition of the magnet thin films 73 and 74 was SmCo ₅ and was formed after the magnetic field heat treatment of the magnetic field detecting element 71 was completed by RF sputtering (Ar atmosphere) in a magnetic field. The magnetic field of the RF sputtering in the magnetic field was applied in the direction in which the magnet thin films 73 and 74 were to be magnetized, and the magnetic field intensity was set to 3500 e or more. For patterning of the magnet thin films 73 and 74, a lift-off method or an ion milling method was used. The residual magnetic flux density of the magnet thin films 73 and 74 under the film forming conditions was 0.81T.
[0052]
The electrode pads 75, 76, 77 and the connection lines 72 were formed of a Ti / Cu thin film.
[0053]
More specifically, the dimensions of the magnet thin films 73 and 74 are 3 mm in length, 1.5 mm in width, and 2.0 μm in film thickness. The two magnet thin films 73 and 74 were arranged at positions separated by 20 μm from the magnetic field detecting element 71 to the left and right. The connection line 72 for electrically connecting the magnetic field detecting element 71 and the magnet thin films 73, 74 and the electrode pads 75, 76, 77 are formed after all the magnetic films have been formed. In order to measure the impedance by the reflection method using the method, a pad for contacting a GSG probe was formed at one end of the element, and the magnetic field detection element 71 and the magnet thin films 73 and 74 at the other end were short-circuited.
[0054]
The evaluation of the magnetic field detection characteristics of the element was performed by measuring a change in the element impedance when an external magnetic field Hex was applied by a Helmholtz coil. The measurement was performed by a reflection method using a network analyzer (for example, HP4396B).
[0055]
The measurement results of the above-described magnetic field detection element characteristics will be described.
[0056]
FIG. 8 is a characteristic diagram of impedance (absolute value) with respect to an external magnetic field Hex (Oe) of the magnetic field detection device according to the first embodiment of the present invention. The broken line in FIG. 8 is a characteristic before the thin film magnet is combined, and is a symmetrical characteristic with the position of the external magnetic field 0 as the axis of symmetry. Further, the solid line in FIG. 8 shows the characteristics when the magnet thin film of the present embodiment is combined, and it can be seen that the characteristic is at the operating point of the element at the position of the external magnetic field 0. As can be seen from the comparison between the solid line and the broken line, even if the SmCo ₅ magnet thin films 73 and 74 are used as the conductive paths, the resistance increase is slight, and there is no characteristic deterioration due to the use of the magnet thin films as the conductive paths. You can see that.
[0057]
FIG. 9 is a diagram showing the environmental degradation characteristics of the residual magnetic flux density of the SmCo ₅ magnet thin film, in which the horizontal axis represents the exposure time at 85 ° C. and 85% RH [hr], and the vertical axis represents the residual magnetic flux density Br [T]. The measurement was performed by performing an acceleration test in a high temperature and high humidity environment of 85 ° C. and 85% RH using a constant temperature and humidity chamber. As a result, even when left in an environment of 85 ° C. and 85% RH for 175 hours, no extreme deterioration of the residual magnetic flux density was observed, and the surface of the thin film was in a beautiful state maintaining gloss.
[0058]
These results show that the SmCo ₅ magnet thin film has good environmental resistance, and is expected to be able to withstand a practical environment without forming a special protective film. Therefore, the following element structure is also effective. That is, as shown in FIG. 10, the magnet thin film 78 (same as 73 and 74) is used as a connection line without using the connection line 72 made of the Ti / Cu thin film shown in FIG.
[0059]
The disturbance of the bias magnetic field at this time does not not only deteriorate the element characteristics extremely, but also enables an element having higher environmental resistance than the Ti / Cu film to be formed, and has an advantage that a process of manufacturing a connection line can be omitted. is there.
[0060]
(Example 2)
FIG. 11 is a diagram showing a layout and an element structure of a magnetic field detection element and a magnet thin film according to a second embodiment of the present invention.
[0061]
In this figure, 81 is a magnetic field detecting element (magnetic impedance element), 82 and 83 are SmCo ₅ magnet thin films, and 84 and 85 are electrode pads.
[0062]
The magnetic field detecting element 81 according to the second embodiment of the present invention realizes a composite magnetic field detecting element having a small and thin bias applying structure. However, the merits of the present bias structure composite magnetic field detecting element 81 are not limited to this. But it works. An example will be described below.
[0063]
The magnetic material composition of the magnetic field detecting element 81 was Co ₈₅ Nb ₁₂ Zr ₃ and was formed on a glass substrate by RF sputtering (Ar atmosphere). The device dimensions were 2 mm in length, 20 μm in width, and 2.1 μm in film thickness, and were patterned using a lift-off method or an ion milling method. The magnetic film was subjected to a heat treatment in a magnetic field after film formation to impart magnetic anisotropy. The heat treatment conditions in a magnetic field are a heat treatment in a rotating magnetic field (40 kA / m, 400 ° C., 2 hours) and a heat treatment in a static magnetic field (40 kA / m, 400 ° C., 1 hour).
[0064]
The composition of the magnet thin films 82 and 83 was SmCo ₅ and was formed after the heat treatment in the magnetic field of the magnetic field detecting element 81 was completed by RF sputtering in a magnetic field (Ar atmosphere). The magnetic field of the sputtering in the magnetic field was applied in a direction in which the magnet thin films 82 and 83 were to be magnetized, and the magnetic field strength was set to 3500 e or more. For patterning of the magnet thin films 82 and 83, a lift-off method or an ion milling method was used. The residual magnetic flux densities of the magnet thin films 82 and 83 under the film forming conditions were 0.81T. The electrode pads 84 and 85 were formed of a Ti / Cu thin film.
[0065]
More specifically, magnet thin films 82 and 83 are disposed on the left and right sides of the bias structure composite magnetic field detecting element 81, and a Cu thin film compatible with solder bonding is laminated on the magnet thin films 82 and 83, and printed. The structure is such that the surface mounting electrode pads 84 and 85 are mounted on the substrate. The dimensions of the SmCo ₅ magnet thin films 82 and 83 are 3 mm in length, 1.5 mm in width, and 2.0 μm in film thickness. The two magnet thin films 82 and 83 were arranged at positions 20 μm apart from each other to the left and right from the magnetic field detecting element. The electrode pads 84 and 85 were formed after all the magnetic films had been formed.
[0066]
The bias structure composite magnetic field detecting element 81 has a structure in which the ends of the magnetic field detecting element are widened, and the ends are connected to different magnet thin films 82 and 83, respectively, to form connection lines.
The element structure shown in FIG. 11 looks like the same coplanar line shape as the first embodiment, but is completely different from the coplanar line in view of the current path. When the sensor element according to the present embodiment is driven at a high frequency of 100 MHz or more, the effect of the stray capacitance between the magnet thin films 82 and 83 used as the electrodes increases, and the sensor sensitivity decreases. Therefore, the element of this embodiment is effective for an element driven in a frequency region of 100 MHz or less.
[0067]
FIG. 12 is a schematic diagram of the magnetic detection device of the present invention surface-mounted on a printed circuit board.
[0068]
In this figure, 91 is a substrate, 92 is a magnetic field detecting section (magnetic impedance element), 93 and 94 are connection lines, 95 and 96 are magnet thin films, 97 is a printed board, 98 and 99 are circuit patterns, 101 and 102 are circuits. This is a solder for connecting the patterns 98 and 99 and the magnet thin films 95 and 96 (soldering by a reflow soldering process).
[0069]
As described above, the magnetic detection device has a structure suitable for automatic mounting by a mounting device and a reflow soldering process, or a surface mounting process using a conductive resin. A suitable magnetic detection device can be manufactured with a simple structure, and an inexpensive bias structure combined magnetic detection device can be provided.
[0070]
According to the present invention, as described above, the magnet thin film having conductivity for applying the bias magnetic field used as a part of the conductive path in the element drive circuit is brought into close proximity with the magnetic field detection unit until it is electromagnetically coupled. By doing so, the characteristic impedance generated between them can be controlled.
[0071]
By using a magnet thin film as an electrode, a slot line having a transmission line structure capable of controlling the characteristic impedance to be constant can be formed between the slot line and the magnetic field detection unit.
[0072]
Using a magnet thin film as an electrode, a coplanar line, which is a controllable transmission line with a constant characteristic impedance, can be formed with the magnetic field detection unit.
[0073]
Using a magnet thin film as an electrode, a strip line or a microstrip line, which is a controllable transmission line with a constant characteristic impedance, can be formed with the magnetic field detection unit.
[0074]
The area of the magnet thin film can be made larger than that of the magnetic field detection unit, and the magnetic field detection unit can be arranged so as not to be close to the magnetic pole of the thin film magnet, and so that the end of the magnetic field detection unit and the magnetic pole are at a uniform distance.
[0075]
An insulating structure can be introduced to provide an electrically divided magnet thin film.
[0076]
An electrode material is laminated on the magnet thin film, and this can be used as a current-carrying electrode for the magnetic field detecting element.
[0077]
The magnet thin film can be configured as a current-carrying electrode for the magnetic field detection element.
[0078]
According to the present invention, a bias magnetic field is applied by a magnet thin film, and the following features are provided.
[0079]
(1) Use a magnet material having conductivity for the magnet thin film.
[0080]
(2) By providing the magnet thin film with an electric circuit function simultaneously with the application of the bias magnetic field, interference between the magnet thin film and the electric circuit is eliminated, and miniaturization and low power consumption are achieved.
[0081]
(3) High-frequency characteristics can be improved by controlling the characteristic impedance between the sensor element and the magnet thin film.
[0082]
Further, a small-sized and low-power-consumption magnetic impedance sensor that does not require a bias coil can be realized, and is suitable for mounting a magnetic sensor on a portable device or the like.
[0083]
It should be noted that the present invention is not limited to the above embodiment, and various modifications are possible based on the spirit of the present invention, and these are not excluded from the scope of the present invention.
[0084]
【The invention's effect】
As described above, according to the present invention, the following effects can be obtained.
[0085]
(A) For a magnetic field detection device that requires a bias magnetic field, a bias magnetic field is applied using a conductive magnet thin film, and at the same time, a coil that generates a bias magnetic field by current is added by using this magnet thin film as a conductive path. A bias magnetic field for securing the operating point can be obtained without the need for this, and at the same time, the role of the electrode structure is assigned to the magnet thin film, which simplifies the structure of the magnetic field detection device and reduces the size of the magnetic field detection device. can do.
[0086]
(B) In a magnetic field detecting device driven by introducing a high-frequency current to a magnetic field detecting element, by using a magnet thin film as a ground conductor and configuring a transmission line, it is possible to design the characteristic impedance to be constant, and to obtain a bias magnetic field structure. Is effective as a high-frequency drive type magnetic field detection device that combines the above. As transmission lines, slot lines, coplanar lines, strip lines, and microstrip lines can be realized.
[0087]
(C) By applying a bias magnetic field using a conductive magnet thin film and simultaneously using the magnet thin film as a conductive path and further forming an electrode pad on the magnet thin film, manufacturing a circuit module for surface mounting or the like. A small magnetic field detection device applicable to the process can be realized.
[Brief description of the drawings]
FIG. 1 is a schematic view of a magnetic field detecting device according to a first embodiment of the present invention, which has a structure in which a magnet thin film is disposed on one of right and left sides of a magnetic field detecting unit with respect to a magnetic field detecting direction.
FIG. 2 is a schematic view of a magnetic field detecting device having a structure in which a high-frequency transmission line is formed using a magnet thin film as a slot line ground electrode according to a second embodiment of the present invention.
FIG. 3 is a schematic view of a magnetic field detecting device according to a third embodiment of the present invention, having a structure in which magnet thin films are disposed on both the left and right sides of a magnetic field detecting unit with respect to a magnetic field detecting direction.
FIG. 4 is a schematic view of a magnetic field detection device according to a fourth embodiment of the present invention, which has a structure in which a magnet thin film is arranged below a magnetic field detection unit with respect to a magnetic field detection direction.
FIG. 5 is a schematic view of a magnetic field detection device according to a fifth embodiment of the present invention, which has a structure in which magnet thin films are disposed both above and below a magnetic field detection unit with respect to a magnetic field detection direction.
FIG. 6 is a schematic view of a magnetic field detection device according to a sixth embodiment of the present invention, which has a structure in which a magnetic field detection unit is disposed inside a hole formed in a magnet thin film.
FIG. 7 is a diagram illustrating a layout and an element structure of a magnetic field detection element and a magnet thin film according to the first embodiment of the present invention.
FIG. 8 is a characteristic diagram of impedance (absolute value) with respect to an external magnetic field Hex (Oe) of the magnetic field detection device according to the first embodiment of the present invention.
FIG. 9 is a diagram showing the environmental degradation characteristics of the residual magnetic flux density of the SmCo ₅ magnet thin film showing Example 1 of the present invention.
FIG. 10 is a diagram showing a modification of the layout and element structure of the magnetic field detection element and the magnet thin film according to the first embodiment of the present invention.
FIG. 11 is a diagram illustrating a layout and an element structure of a magnetic field detection element and a magnet thin film according to a second embodiment of the present invention.
FIG. 12 is a schematic diagram of the magnetic detection device of the present invention surface-mounted on a printed circuit board.
[Explanation of symbols]
1,11,21,41,51,61,91 Substrates 2,4,6,12,14,15,17,22,24,25,27,28,30
, 42, 44, 65, 67, 75, 76, 77, 84, 85 Electrode pads 3, 13, 23, 43, 52, 63, 92 Magnetic field detector (magnetic impedance element)
5,16,26,29,45,54,55,66,68,78,95,96
Magnet thin films 7, 18, 31, 47, 56, 69 Magnet magnetization directions 8, 19, 32, 48 High-frequency current application directions 9, 20, 33, 49, 57, 70 Magnetic field detection directions 46, 53 Insulating films 62, 64 Connection electrodes 71, 81 Magnetic field detection element (magnetic impedance element)
72, 93, 94 Connection lines 73, 74, 82, 83 SmCo ₅ magnet thin film 97 Printed circuit boards 98, 99 Circuit patterns 101, 102 Solder (Soldering by reflow soldering process)

Claims (13)

In a magnetic field detection device that applies a high frequency directly to a magnetic material and uses the impedance change due to an external magnetic field,
(A) a magnetic impedance element;
(B) a conductive magnet thin film connected to the magnetic impedance element,
(C) A magnetic field detecting device wherein the magnet thin film is provided with a function of an electric circuit simultaneously with the application of a bias magnetic field. 2. The magnetic field detecting device according to claim 1, wherein the magnet thin film is used as a part of a conductive path in an element driving circuit. 2. The magnetic field detecting device according to claim 1, wherein high frequency characteristics are improved by controlling a characteristic impedance between the magnetic impedance element and the magnet thin film. 2. The magnetic field detecting device according to claim 1, wherein the magnet thin film is disposed on one of the right and left sides of the magnetic impedance element. 2. The magnetic field detection device according to claim 1, wherein the magnet thin film is used as a ground electrode of a slot line to form a high-frequency transmission line. 2. The magnetic field detecting device according to claim 1, wherein the magnet thin film is disposed on the left and right of the magnetic impedance element, and the magnet thin film is used as a ground electrode of a coplanar line to form a high-frequency transmission line. . 2. The magnetic field detecting device according to claim 1, wherein the magnet thin film is disposed below the magnetic impedance element via an insulating film. 2. The magnetic field detecting device according to claim 1, wherein an insulating structure is introduced and a magnet thin film that is electrically divided is used. 2. The magnetic field detecting device according to claim 1, wherein the magnet thin film is disposed above and below the magnetic impedance element via an insulating film, and the magnet thin film is used as an electrode. 2. The magnetic field detecting device according to claim 1, wherein the magnet thin film is used as a current-carrying electrode of a magnetic field detecting element. 11. The magnetic field detecting device according to claim 10, wherein an electrode material is laminated on the magnet thin film. 2. The magnetic field detecting device according to claim 1, further comprising two magnet thin films formed in a substantially semi-elliptical shape around the magnetic impedance element. In the magnetic field detecting device according to any one of claims 1 to 12, wherein, as the magnet thin, the magnetic field detection device characterized by using the SmCo ₅ alloy.

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