JP2003161770A - Magnetism detecting element - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To make a dual arrangement of elements realizable by reducing substrate stress without increasing the size of the elements or their mounting area. <P>SOLUTION: Then film magnetic cores made of one strip-shaped magnetic body or obtained by electrically connecting two strip-shaped magnetic bodies or more to each other are formed on the both front and back surfaces of a glass substrate 12, (the film magnetic core on the upper surface is indicated with a mark 11a, the film magnetic core on the lower surface is with a mark 11b, and conductor for electrically connecting the two strip-shaped magnetic bodies or more are with a mark 13 in Fig.). It is possible to eliminate substrate distortion due to residual stress associated with sputtering after film formation. By making detecting distances of magnetic fields approximately the same between the film magnetic cores, corrections on differences in arrangement locations are made unnecesser. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetic sensor for magnetic detection or a current sensor using the same, and more particularly to a highly sensitive magnetic detection element utilizing a magnetic impedance effect.

[0002]

2. Description of the Related Art In recent years, information devices and measurement / control devices have been rapidly improved in performance, reduced in size and thickness, and reduced in cost. With rapid development of these devices, magnetic sensors, current sensors and the like used in them have been developed. The demands for small size, low cost and high sensitivity are increasing.

Hall elements, magnetoresistive effect elements (MR elements), giant magnetoresistive effect elements (GMR elements), flux gate sensors, and the like are known as magnetic sensors that have been conventionally used, and current sensors are also known. Those using a current transformer are known. For example,
A magnetic head used in a hard disk device as an external storage device of a computer has been improved in performance from a conventional bulk type inductive magnetic head to an MR head, and at present, a giant magnetoresistive effect element (GMR element). There are active researches to apply.

Further, in the rotary encoder, which is a rotation sensor of a motor, the magnetic flux leaking to the outside has become weak with the miniaturization of the magnet ring, and a magnetic sensor with high sensitivity is required instead of the current MR element. Electronic devices that use current sensors have been developed instead of conventional mechanical devices such as breakers, but it is difficult to make them smaller with conventional current transformers, and in terms of sensitivity and detection range, etc. There is a demand for higher sensitivity and wider range of magnetic sensors.

In order to meet these requirements, a magneto-impedance sensor using the magneto-impedance effect of amorphous wire (hereinafter, also simply referred to as MI effect) has been proposed (Japanese Patent Laid-Open No. 06-281712 and Japanese Patent Laid-Open No. 07-18121).
8-330645, "Journal of Applied Magnetics of Japan" vo
l. 18, p493, 1994 etc.). The MI effect means that when the external magnetic field changes while a high-frequency current is applied to the magnetic material, the magnetic permeability of the magnetic material changes, and accordingly, the impedance of the magnetic material is several tens to several hundreds compared to when the magnetic field is zero. It is a phenomenon that changes. Thus, by measuring the voltage across the magnetic body, it is possible to detect minute changes in the external magnetic field of about several Gauss. This MI effect can be seen not only in the amorphous wire but also in the magnetic ribbon and the magnetic thin film. Especially, the thin film can be small and thin.
Various structures have been proposed due to their excellent reliability and mass productivity (“Materials Study Group of the Institute of Electrical Engineers of Japan”, MAG
-94-75, 1994, "Journal of the Institute of Electrical Engineers of Japan" 115
Vol. 10, p. 949, 1995, JP-A-08-0758.
No. 35, etc.).

An MI element using a thin film is composed of a thin film magnetic core obtained by processing a high magnetic permeability soft magnetic film, which imparts magnetic anisotropy and induces uniaxial anisotropy, into a strip shape. The magnetic anisotropy is induced by applying a magnetic field at the time of forming the magnetic film, and further by performing heat treatment at about 150 to 400 ° C. in a rotating magnetic field or a static magnetic field. The direction of the easy axis of magnetization is generally the minor axis (line width) direction of the strip structure. The MI element has a characteristic that its impedance changes depending on the magnetic field of its longitudinal component. The MI characteristic at this time is shown in Fig. 1.
As shown in FIG. 3, the impedance peaks are taken depending on whether the magnetic field is positive or negative, and the characteristic is that the impedance is symmetrical depending on whether the magnetic field is positive or negative. Further, the rate of change shows a very large change of several tens to several hundreds%.

FIG. 13 shows the characteristics when the axis of easy magnetization is the line width, but MI characteristics are exhibited even if magnetic anisotropy is imparted in the length direction. The characteristic at that time is such that the impedance is highest when the magnetic field is 0 and decreases as the absolute value of the magnetic field increases. In this case as well, the impedance is symmetrical depending on whether the magnetic field is positive or negative. The direction of the detected magnetic field in this case is also the component in the length direction of the thin film magnetic core.

The change in impedance in these MI characteristics is caused by the change in magnetic permeability in the state where a high frequency current is applied to the thin film magnetic core. When impedance is separated into a resistance component and an inductance component, both change due to a change in magnetic permeability, but the resistance component having a large absolute value is dominant in the change. The resistance change due to the change in permeability is basically due to the skin effect that occurs when a high-frequency current flows through a magnetic material.Therefore, to increase the skin effect, either increase the frequency of the high-frequency current or use the thin-film magnetic field. A method of increasing the film thickness of the magnetic material that is the core is effective.

As described above, the MI element is characterized in that the impedance changes greatly with respect to the magnetic field. However, by applying a bias magnetic field to the element and operating it at a point where the impedance changes greatly with respect to the magnetic field. Further, the sensor responds to the magnetic field with high sensitivity. A point a in FIG. 13 indicates the bias point (bias magnetic field). To apply this bias magnetic field, a coil (bias coil) is formed around the element, and a current is applied to the coil to generate a magnetic field. It is necessary to generate. Also,
A coil is also required for the method of applying a negative feedback magnetic field for the purpose of improving the linearity of sensitivity. When an amorphous wire is used, a Cu wire or the like is wound directly around the wire to form a coil. However, in a MI element formed of a thin film, the coil is thin film on the same substrate as the magnetic material pattern. A structure formed by the method has been proposed ("Journal of the Applied Magnetics Society of Japan", vol. 21, p649, 1).
997, Japanese Patent Laid-Open No. 09-269084).

[0010]

As described above, the MI element has a structure using an amorphous wire and a structure using a thin film, but the reproducibility (stability) of characteristics, reliability,
It can be said that using a thin film is advantageous in terms of mass productivity.
If a thin film is used, it is formed on the non-magnetic substrate by sputtering, etc., a fine pattern is formed using a photosensitive material such as resist, and wet etching or dry etching such as ion beam etching is used. , It is necessary to process into a fine pattern. At this time, an ultraviolet exposure method using a photomask is usually used for patterning the photosensitive material, but after the magnetic film is sputtered,
There is a problem that a strong residual stress is generated inside the magnetic film, and the warp of the substrate accordingly causes deterioration of the pattern accuracy. The stress after forming the sputtered thin film can be controlled to some extent under the film forming conditions, and the residual stress can be suppressed.However, in the case of an amorphous sputtered film, heat treatment of the formed magnetic film causes a strong tensile stress. Occur. As described above, in order to induce the magnetic anisotropy of the magnetic film, heat treatment in a magnetic field is necessary. Therefore, if this heat treatment is performed, tensile stress is generated even if residual stress is controlled after film formation. Since the stress applied to the substrate is (internal stress of the magnetic film x film thickness), particularly when the magnetic film thickness is increased to several μm or more in order to increase the rate of change of the impedance with respect to the magnetic field, the stress is particularly strong. In some cases, a fine pattern cannot be formed because the substrate is largely warped and is not attracted to the substrate stage during exposure.

In order to avoid these stress problems, it is necessary to increase the thickness of the substrate or use a material having a large Young's modulus as the material. However, the latter has a problem that the substrate material is limited. Further, although a method of using a substrate adapted to the linear expansion of the thin film can be used, the substrate material is similarly limited.

On the other hand, since the MI element has very good sensitivity, it is easily affected by disturbance noise. In order to reduce the influence, a method in which two or more similar elements are arranged and their differential outputs are proposed has also been proposed (for example, "Materials of the Institute of Electrical Engineers of Japan", MAG-93-22).
0, 1993).

In particular, when they are formed of thin films, they can be formed on the same substrate, so that there is an advantage that the positional accuracy of a plurality of elements is good. The same applies to a coil-integrated structure in which a bias coil and a negative feedback coil are formed on the same plane, and in this case, there is an advantage that the same coil can be used for two elements (Japanese Patent Laid-Open No. 2000-2).
No. 92506, Japanese Patent Laid-Open No. 2000-284030, etc.) When a plurality of elements are used for differential output,
The positional relationship between the plurality of elements is important. For example, in order to detect a magnetic field generated by a current flowing through a single straight conductor, the magnetic field changes depending on the distance between the conductor and the element, and therefore the distance between the conductor and the plurality of elements needs to be the same. Eg 2
When the individual elements are formed on the same plane, as shown in FIG. 14A, the two elements 142a and 142b are arranged adjacent to each other, or as shown in FIG. Reference numerals 142c and 142d) are taken. In the case of FIG. 14A, the distance from the conductor 141 is the element 142a.
And 142b, the magnetic fields 143a and 143b of the longitudinal components applied to the respective elements are significantly different.
In addition, in the case of FIG. 14B, although the distances between the elements are almost the same, not only the magnetic field decreases due to the large distance,
There is a problem in that the characteristics of the device greatly depend on the mounting accuracy, such as a large change in the output if the device is slightly tilted or vertically displaced.

That is, in the configuration of FIG. 14, there is no problem as long as it is a magnetic sensor used in a place where a uniform magnetic field is generated in a large range such as terrestrial magnetism. Also, in the detection of magnetic flux generated by a magnet, the strength of the magnetic field depends on the distance, and these configurations cannot be said to effectively utilize the advantage of using two elements. In addition, when using a plurality of elements, no matter how the positional accuracy is improved, as many elements as the number of elements, of course, element chips are required, and the mounting area for mounting them increases. Inevitably, there are limits to miniaturization.

Therefore, the object of the present invention is to solve the problems of manufacturing due to the stress as described above, the improvement of the characteristics when a plurality of elements are used, the increase of the chip size, the improvement of the mounting accuracy, etc. It is to provide a highly sensitive magnetic detection element at a cost.

[0016]

In order to solve such a problem, the invention of claim 1 provides a thin film magnetic body obtained by forming a high permeability magnetic film on a non-magnetic substrate and then processing it into a strip shape. A magnetic detection element that utilizes a magneto-impedance effect in which a high-frequency current is applied and an external magnetic field is applied to change its impedance, which is a thin-film magnetic core composed of a single strip-shaped thin-film magnetic body, or two or more. One or more thin film magnetic cores each formed of an assembly of strip-shaped thin film magnetic bodies electrically connected to each other are formed on each of the front and back surfaces of the non-magnetic substrate.

With such a structure, even stress is applied to both surfaces of the non-magnetic substrate, and it is possible to avoid problems in manufacturing due to warpage of the substrate. Further, when forming a plurality of elements, a similar configuration can be realized with a half element area, and the chip area can be reduced to half, as compared with the case of forming the elements on the same plane. As a result, the number of substrates required to form the same number of chips can be halved, and the cost can be reduced.

The invention of claim 2 is characterized in that, in the invention of claim 1, the high-permeability magnetic film is an amorphous magnetic material. Amorphous magnetic materials of Co type and Fe type are known. In both cases, it is difficult to form a thick film because a large internal stress is generated by the heat treatment after film formation. By doing so, formation is possible.

The invention of claim 3 is characterized in that, in the invention of claim 1, the high-permeability magnetic film is a nanocrystalline magnetic material. Examples of nanocrystalline magnetic materials include Fe
-MX [M = Ta, Nb, Hf, Pd, Pt, Ti,
X = C, B, N] are known, but all materials require high temperature annealing of 400 ° C. to 700 ° C. after film formation by sputtering or the like, and large residual stress occurs. For this reason, it is difficult to form a thick film structure, but the invention makes it possible to form it.

According to the invention of claim 4, in the invention of claims 1 to 3, the longitudinal directions of the thin film magnetic cores formed on both surfaces of the substrate are set to be the same direction, and the difference between the outputs is detected to thereby influence the disturbance noise. To improve the temperature characteristics. Also,
The positional relationship between the elements is also plane-symmetrical with respect to the center of the substrate in the plate thickness direction, so that the distance from the magnetic field to be measured is the same.

By doing so, the positional accuracy of each element,
Since the directional accuracy is determined only by the accuracy of photolithography, the difference in angle is almost negligible. Also, when detecting the magnetic field generated by the current flowing through the conductor, the distance is the same regardless of the mounting accuracy.
The magnetic fields applied to the individual elements are the same, and there is no need for correction due to the difference in individual position accuracy.

The invention of claim 5 is characterized in that, in the inventions of claims 1 to 3, the relative angles of the plurality of thin film magnetic cores are changed in the range of 0 to 90 degrees, and are applied individually. By changing the magnetic field, it is possible to obtain an output according to the application. For example, if the angle is 90 degrees, it is possible to detect magnetic fields in two orthogonal axes.

A sixth aspect of the present invention is characterized in that, in the first to fifth aspects, the high magnetic permeability magnetic film forming the thin film magnetic core has a thickness of 1 μm or more. Since the stress of the magnetic film applied to the substrate is proportional to the film thickness,
It is extremely effective when the film is formed thicker than m.

A seventh aspect of the present invention is characterized in that, in the first to sixth aspects, a plurality of thin film magnetic cores are electrically connected in series. According to this configuration, the number of high frequency currents applied to the element can be one, and the circuit is simplified.

According to the invention of claim 8, in the invention of claim 7, a plurality of thin film magnetic cores formed on both surfaces of the non-magnetic substrate are electrically connected in series through through holes formed on both surfaces of the non-magnetic substrate. It is characterized by being With this configuration, the number of sources of high-frequency current to be applied to the element can be one, and the circuit can be simplified. In addition, the elements can be electrically connected only on one side of the substrate. You can
The implementation can be simplified.

The invention of claim 9 is characterized in that a bias coil is wound around the magnetic detection element of any one of claims 1 to 8 with an insulator interposed therebetween. By winding the bias coil, the operating point of the magnetic detection element can be set to the most sensitive position, and the magnetic detection element can have high performance.

A tenth aspect of the present invention is characterized in that a bias coil and a negative feedback coil are wound around the magnetic detection element according to the first to eighth aspects with an insulator interposed therebetween. By winding the bias coil, the operating point of the magnetic detection element can be set to the most sensitive position, and the negative feedback coil can improve temperature characteristics and output linearity.

An eleventh aspect of the present invention is characterized in that, in the ninth aspect, the bias coil is a thin film coil formed of a thin film on the same plane as the thin film magnetic core. As a result, a highly efficient and uniform bias magnetic field can be applied to the thin film magnetic core, and high performance of the device can be realized.

According to a twelfth aspect of the present invention, in the tenth aspect of the present invention, the bias coil and the negative feedback coil are thin-film coils formed on the same plane as the thin-film magnetic core. As a result, a highly efficient and uniform bias magnetic field and negative feedback magnetic field can be applied to the thin film magnetic core, and high performance of the device can be realized.

A thirteenth aspect of the present invention is characterized in that, in the eleventh aspect of the present invention, a thin film coil serving as a bias coil and a negative feedback coil is connected in series. According to this configuration, each of the current generating sources for energizing the bias coil and the negative feedback coil can be made one, and the circuit can be simplified.

A fourteenth aspect of the present invention is characterized in that, in the twelfth aspect of the present invention, the thin film coils serving as the bias coil and the negative feedback coil are electrically connected in series through through holes formed on both surfaces of the non-magnetic substrate. To do. According to this configuration, each of the current sources for energizing the bias coil and the negative feedback coil can be made one, and the circuit can be simplified, and the element and the thin film coil can be connected only on one side of the substrate. Therefore, the implementation can be simplified.

[0032]

1 is a perspective view showing a first embodiment of the present invention.

As shown in the figure, the thin film magnetic cores 11a and 11b as the magneto-impedance elements are formed on both sides of the glass substrate 12 which is a non-magnetic substrate. The thin-film magnetic cores 11a and 11b have a strip shape. This thin film magnetic core exhibits MI characteristics if there is one strip-shaped structure, but in order to increase the absolute value of the impedance, these can be arranged in parallel and electrically connected in series. May be formed of a single magnetic material, or only the connecting portion (folded portion) 13 may be formed of a conductive material. FIG. 1 shows an example in which four thin film magnetic cores are connected in series with a single magnetic material, but it goes without saying that the invention is not limited to this. In the following description, a set of strip-shaped thin film magnetic cores formed on the same plane and electrically connected in series is referred to as a thin film magnetic core.

FIG. 2 is an explanatory view of the manufacturing process of the present invention.

First, as shown in FIG. 2A, a glass substrate 22 (for example, substrate size φ = 4 × 2.54 cm (4
Inch) and a thickness of 0.4 mm), CoHfTaPd, which is an amorphous magnetic material, is used as a high-permeability magnetic film on both surfaces.
On both sides (21a on the front side and 21b on the back side) are formed with a film thickness of 4 μm. The magnetron sputtering method was used for the film formation. In order to stabilize the magnetic anisotropy during film formation, 100 × in the direction of the easy axis of magnetization after processing.
It was performed while applying a magnetic field of 79 A / m. Although other materials are not particularly shown between the glass substrate 22 and the magnetic films 21a and 21b, polyimide is actually formed as an insulating film on the glass substrate. If necessary, an inorganic insulating film such as a silicon oxide film, a silicon nitride film, or alumina, or another organic insulating film may be formed. In order to improve the adhesion, Ti, Cr, Ta, Nb, W or the like may be deposited. In order to align the magnetic anisotropy after forming the magnetic film, 30
Magnetic field heat treatment was carried out for 1 hour in a rotating magnetic field of 0 ° C. and 200 × 79 A / m, followed by 300 ° C. and 200 × 79 A / m.
Magnetic field heat treatment was performed in a static magnetic field of m.

Next, as shown in FIG. 2B, as a mask for processing the magnetic film, the thin film magnetic core patterns 23a and 23b are formed by using a photolithography technique using a photosensitive resin on both surfaces of the magnetic film. To form. A photoresist was used as the photosensitive resin. In addition, exposure during photolithography was performed on both sides simultaneously, and development was also performed at one time. There is no problem if the steps are performed on one side instead of exposing and developing at the same time. However, there is an advantage that the steps can be shortened by performing them simultaneously. Further, a film resist or photosensitive polyimide may be used as the photosensitive resin.

After the mask is formed, as shown in FIG. 2C, the magnetic material on both surfaces is finely processed by ion beam etching using the photosensitive resin pattern as an etching mask. In this embodiment, ion beam etching is applied to the fine processing, but other dry etching processing methods such as reactive ion etching may be applied, or wet etching processing method may be used. Alternatively, any method such as forming a pattern that is the reverse of the present embodiment and forming the pattern by a lift-off method or a method using a metal mask method may be used. In addition, the direction of magnetic field application (direction of easy axis of magnetization) during film formation in a magnetic field and during static magnetic field heat treatment is
Although it is arranged in the width direction of the thin film magnetic core pattern, it is not limited to this direction and may be in the longitudinal direction.

Finally, as shown in FIG. 2 (d), the mask material is removed by plasma etching to obtain the thin film magnetic cores 24a and 24b, and then Ti and Al are continuously formed on the portions to be the electrodes. , Etched. It should be noted that the electrode material may be added as needed in the connection step in the subsequent step. As the material, the above Ti, A
In addition to 1, Cr, Nb, W, Ta, Au, Cu, N
i, Pt, or a multilayer film of these is used. Further, in particular, the magnetic film may be used as it is without forming the metal material.

FIG. 3 shows the amount of warpage of the substrate after each step and after the element formation is completed, and the symbol a shows that according to the present invention. Here, for comparison, the characteristics when the thin-film magnetic core is formed on only one side are indicated by reference numeral B. From a comparison between the two, it can be seen that the method according to the present invention is very effective in reducing the warp of the substrate and is extremely advantageous in the manufacturing process. Although an amorphous magnetic material is used as the magnetic film here, for example, Fe-MX [M = Ta, Nb, Hf,
It is clear that the use of the nanocrystalline magnetic material known for the structure of Pd, Pt, Ti and X = C, B, N] also has a great effect. Further, structurally, the elements on the front and back of the substrate are formed so that the longitudinal directions thereof are the same, but the positional deviation at this time is ± 2 μm, and the angular deviation is 0.06 degrees or less. As a result, the magnetic fields to be measured for the thin film magnetic cores are almost the same and the external magnetic fields are also the same. Therefore, by taking the differential between them, the disturbance noise can be easily removed. Also, regarding the change in characteristics due to temperature, since the elements formed on the front and back of the substrate show the same characteristics,
Correction is easy.

FIG. 4 is a top view showing a modification of FIG.

As is clear from the figure, the thin film magnetic core 4
The relative angles of 1a and 41b can be arbitrarily set. In the figure, the relative angle is approximately 45 degrees. By doing this, when there is another conductor adjacent to the conductor where the current to be measured flows,
It is possible to make a correction by considering the outputs of both.

Particularly, as shown in FIG. 5, the thin film magnetic cores 51a,
When the relative angle of 51b is 90 degrees, the respective detectable magnetic fields are orthogonal to each other, so that it can be used as a biaxial magnetic detection element.

FIG. 6 shows the relationship between the film thickness of the magnetic film forming the thin film magnetic core and the warp of the substrate after the element is completed. In addition,
Size φ = 4 × 2.54cm (4inch) on the board,
A glass substrate having a film thickness of 0.4 mm was used. When a semiconductor process is used, it is generally necessary to set the warpage amount to 100 μm or less, so that a film thickness of 1 μm or more is particularly effective. It should be noted that as the diameter of the substrate increases, the amount of warpage increases further, so the present invention is more effective.

When the above-mentioned element is actually used, it is mounted on a printed circuit board, a lead frame, etc., but since the connection between the thin film magnetic core on the back surface of the substrate and the mounting substrate is surface mounting, bump bonding or solder bonding is performed. , Anisotropic conductive material, conductive adhesive, stud bump bonding, etc. are used. Further, the high frequency current may be separately applied to each of these thin film magnetic cores, but by electrically connecting in series on the printed circuit board, the high frequency current generation source can be made common.

FIG. 7 shows another embodiment of the present invention.

This is a thin film magnetic core 71a, 71b formed on both surfaces of the substrate by forming a through hole in the glass substrate 72 and passing through the conductive layers 73, 74 filled with a conductor.
Are electrically connected in series. That is, one electrode of the thin film magnetic core 71 a is electrically connected to the thin film magnetic core 71 b through the conductive layer 73, and one electrode of the thin film magnetic core 71 b is connected to the electrode 75 on the substrate surface through the conductive layer 74.

FIG. 8 shows the manufacturing process of FIG.

First, holes 82a and 82b penetrating both surfaces are formed in the glass substrate 81 by sandblasting. The diameter of the through hole is 100 μm. Next, a conductive resin is embedded in the through holes to form conductive layers 83a and 83b, and Ti / Cu / Ni / Au multilayer electrodes 84 are formed on the front and back surfaces of the substrate.
a, 84b and 84c, 84d are formed.

After that, as in FIG. 2, the thin film magnetic core 85 is used.
a and 85b are formed. One electrode 86a of the thin film magnetic core 85a is connected to the thin film magnetic core 85b through the conductive layer 83a.
Is electrically connected to the electrode 86b of the thin film magnetic core 85b.
The other electrode 86c is connected to the electrode 84b on the substrate surface through the conductive layer 83b.

In the above, the sand blast is used for the processing of the through hole, but ultrasonic processing, water jet, etc. may be used, and wet etching may be used if the accuracy may be poor. When precision is particularly required, a semiconductor process such as dry etching may be used. In addition, the conductive layer embedded in the through hole is C like a general printed circuit board.
Alternatively, a plating method such as u (electrolytic or electroless) may be used. Further, any method such as tungsten filling used in the multilayer ceramic substrate may be used.

With the above arrangement, the electrical connection can be established only on the surface of the substrate, so that the electrical connection can be established only by wire bonding, for example, and mounting restrictions can be reduced.

FIG. 9 is a sectional view showing another embodiment of the present invention, showing an example of applying a bias magnetic field in order to operate the MI element with high sensitivity.

First, the MI element 91 is connected to the lead frame 92.
The thin film magnetic core on the back surface of the substrate is electrically connected to the lead frame 92 by stud bump bonding, and the thin film magnetic core on the front surface of the substrate is wire bonded. Next, the bobbin 93 of the coil is formed around them using an insulating resin. Then, a Cu wire is wound around the bobbin 93 to form the bias coil 94. Note that a negative feedback coil can be formed by winding a coil in parallel with this. Although the configuration shown in FIG. 9 has no problem in terms of characteristics, it is desirable to cover the entire coil with resin (case molding) and finally perform lead bending in order to obtain reliability.

By applying the bias magnetic field as described above, the operating point of the MI element can be set to the most sensitive point. Further, by applying the negative feedback magnetic field using the negative feedback coil, it is possible to obtain characteristics having excellent temperature characteristics and good linearity. It should be noted that only one bias coil and one negative feedback coil are required for two MI elements, and the element area is smaller than the method of arranging a plurality of elements on a plane as described above, so that a small size and a thin shape can be realized. The stability of the characteristics is as described above.

FIG. 10 is a plan view showing still another embodiment of the present invention. The bias coil 102 and the negative feedback coil 10 are arranged on the same plane as the MI elements 101 on both sides of the substrate.
3 is formed. If the negative feedback coil is unnecessary, only the bias coil may be used.

FIG. 11 shows the manufacturing process.

First, as shown in FIG. 11A, on both surfaces of the glass substrate 111, Ti and Al as lower coil materials are formed.
Of 0.1 μm and 1 μm in thickness (reference numeral 11)
2a, 112b). Next, as shown in FIG.
The lower coil patterns 113a, 11a are formed by photolithography using a photoresist and wet etching.
3b is formed. The exposure at the time of resist patterning was performed by double-sided simultaneous exposure, and the development was also simultaneous development. For wet etching, Al was used as a mixed aqueous solution of phosphoric acid, nitric acid, and acetic acid, and Ti was used as a hydrofluoric acid aqueous solution. The resist was stripped using an organic alkali stripping solution.

Next, using photosensitive polyimide, FIG.
Insulating films 114a and 114b are formed as shown in FIG. At the same time, contact holes 115a and 115b for electrically connecting to the upper coil are also formed. Thereafter, as in FIG. 2, the thin film magnetic core 116 is
a and 116b are formed (see FIG. 11D), and
Insulating film 1 on thin film magnetic core using photosensitive polyimide
17a and 117b are formed (see FIG. 11E). Finally, the steps (a) and (b) are repeated until the upper coil 1
18a and 118b are formed as shown in FIG. Although omitted here, if necessary, an insulating film may be formed on both surfaces of the upper coil pattern on both surfaces to serve as a protective film.

As shown in FIG. 11, in addition to the advantage of forming the thin film magnetic cores on both surfaces of the substrate as described above, by forming the coil with a thin film, further miniaturization and thinning can be realized, and the coil can be formed. By forming a thin film, a bias magnetic field and a negative feedback magnetic field can be stably applied with high efficiency, and further high performance and stabilization of characteristics can be achieved.

By electrically connecting the thin film magnetic core, the bias coil, and the negative feedback coil on both sides through an external substrate in series, the current source can be made common and the circuit is simplified and the power consumption is low. In addition to being made more efficient, higher current and higher stability can be realized because the currents flowing through each element are the same.

By forming the structure of FIG. 11 on a substrate having through holes and a conductive layer as shown in FIGS. 7 and 8,
The thin film magnetic cores on both sides of the substrate, the bias coil, and the negative feedback coil can be electrically connected in series.
As a manufacturing method thereof, the step of FIG. 11 is performed after the steps of FIGS. With such a configuration, each electrical connection can be made only on the surface of the substrate, so that the electrical connection can be made by, for example, only wire bonding as described above, and mounting restrictions are reduced.

The magnetic detecting element according to the present invention is effective not only for the Co type amorphous magnetic material formed by the above-mentioned sputtering method but also for all magnetic materials. That is, the same applies not only to the above-mentioned nanocrystalline magnetic materials that require heat treatment at high temperature, but also to crystalline magnetic materials such as Ni—Fe. Further, the film forming method is not limited at all, and a sputtering method, vacuum vapor deposition, CVD or ion beam sputtering can be used, and a Ni—Fe based material formed by a plating method or a Co—Ni material can be used. −
It can also be applied to Fe-based, CoFe-based, and CoNi-based magnetic films.

In the above embodiments, one thin film magnetic core is arranged on each side of the substrate, but various arrangements can be considered for the arrangement. For example, as shown in FIG. 12, the size and number of front surface side elements and back surface side elements may be changed,
A multidirectional magnetic sensor in which magnetic field detection has various directions by changing its angle can be considered as a modification. Of course, the same applies to the case where a thin film coil including a bias coil and a negative feedback coil is formed on these elements.

[0064]

According to the present invention, a thin film magnetic core made of a thick magnetic material can be formed without causing a production problem due to stress when a thick magnetic material is formed. It is possible to improve. Further, a plurality of MI elements can be differentially operated without increasing the element size, and stable element characteristics with less characteristic variation due to mounting accuracy can be obtained.

[Brief description of drawings]

FIG. 1 is a perspective view showing a first embodiment of the present invention.

FIG. 2 is an explanatory view of the manufacturing process of FIG.

FIG. 3 is a graph showing changes in the amount of warpage of the substrate during the manufacturing process.

FIG. 4 is a layout diagram showing an example of a layout of front side and back side elements.

FIG. 5 is an arrangement diagram showing another example of arrangement of front side and back side elements.

FIG. 6 is a graph showing the relationship between the film thickness of the magnetic film and the amount of warpage of the substrate.

FIG. 7 is a perspective view showing another embodiment of the present invention.

8 is an explanatory diagram of the manufacturing process of FIG. 7. FIG.

FIG. 9 is a sectional view showing another embodiment of the present invention.

FIG. 10 is a plan view showing still another embodiment of the present invention.

11 is an explanatory view of the manufacturing process of FIG.

FIG. 12 is a plan view showing still another embodiment of the present invention.

FIG. 13 is a graph showing general characteristics of a magnetic impedance element.

FIG. 14 is an arrangement diagram showing a conventional arrangement method of two MI elements.

[Explanation of symbols]

11a, 11b, 24a, 24b, 41a, 41b, 5
1a, 51b, 71a, 71b, 116a, 116b ...
Thin film magnetic core, 12, 22, 111 ... Glass substrate, 21
a, 21b ... Magnetic film, 73, 74, 83a, 83b ... Conductive layer, 75, 84a, 84b ... Electrode, 82a, 82b ...
Through holes, 91, 101 ... Magneto-impedance element (MI
Element), 92 ... Lead frame, 93 ... Bobbin, 94,
102 ... Bias coil, 103 ... Negative feedback coil, 11
4a, 114b, 117a, 117b ... Insulating film, 115
a, 115b ... Contact holes, 118a, 118b
…coil.

Claims (14)

[Claims] 1. A magnetic material in which a high-permeability magnetic film is formed on a non-magnetic substrate and then processed into a strip shape to apply a high-frequency current to a thin-film magnetic material to apply an external magnetic field to change its impedance. A magnetic sensing element utilizing the impedance effect, wherein a thin film magnetic core made of a single strip-shaped thin film magnetic body or a thin film magnetic core made of an assembly of two or more strip-shaped thin film magnetic bodies electrically connected, One or more magnetic detection elements are formed on each of the front and back surfaces of the non-magnetic substrate. 2. The magnetic detection element according to claim 1, wherein the material of the high-permeability magnetic film is an amorphous magnetic material. 3. The magnetic sensing element according to claim 1, wherein the high-permeability magnetic film is a nanocrystalline soft magnetic film. 4. The thin film magnetic cores have the same longitudinal direction, and the positional relationship of each thin film magnetic core is plane-symmetric with respect to the substrate. The magnetic detection element described. 5. The magnetic detecting element according to claim 1, wherein the relative angle in the longitudinal direction of each of the thin film magnetic cores is changed in the range of 0 to 90 degrees. 6. The magnetic detection element according to claim 1, wherein the high magnetic permeability magnetic film has a thickness of 1 μm or more. 7. The magnetic detecting element according to claim 1, wherein a plurality of thin film magnetic cores formed on both surfaces of the non-magnetic substrate are electrically connected in series to each other. . 8. A plurality of thin film magnetic cores formed on both surfaces of the non-magnetic substrate are electrically connected through through holes formed in the non-magnetic substrate. 2. The magnetic detection element according to any one of 1. 9. A bias coil is wound around the thin film magnetic core via an insulator.
8. The magnetic detection element according to any one of 1 to 7. 10. The magnetic detecting element according to claim 1, wherein a bias coil and a negative feedback coil are wound around the thin film magnetic core via an insulator. 11. The magnetic sensing element according to claim 9, wherein the bias coil is formed of a thin film on the same plane as the thin film magnetic core. 12. The magnetic detecting element according to claim 10, wherein the bias coil and the negative feedback coil are formed of a thin film on the same plane as the thin film magnetic core. 13. The magnetic detecting element according to claim 10, wherein the bias coil and the negative feedback coil are electrically connected in series. 14. A plurality of thin film magnetic cores formed on both surfaces of the non-magnetic substrate are electrically connected in series to each other through through holes formed in the non-magnetic substrate, and a thin film bias coil and a negative feedback are provided. The magnetic detection element according to claim 12, wherein the coils are electrically connected in series through through holes formed in the non-magnetic substrate.