JP2001004726A - Magnetic field sensor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a high-sensitivity and small magnetic field sensor by a constitution wherein a relationship between the shape in the cross section in the width direction of a magnetic thin film, i.e., the film thickness near the central part in the width direction, and the film thickness near the end part in the width direction satisfies a specific condition. SOLUTION: For example, a conductor coil 20 for magnetic-field detection is wound on magnetic thin films 11, 12, 13, 14. The conductor coil 20 is formed normally as a thin-film coil. Then, the width in the cross section in the width direction of the nearly rectangular magnetic thin films 11, 12, 13, 14 is designated as W, the film thickness near the end part in the width direction as t1, and the film thickness near the central part as t2. Then, the magnetic thin films are constituted so as to have a cross-sectional shape at t2/t1>1, preferably at t2/t1>1.2, or more preferably at t2/t1>1.5. At this time, the film thickness t1 near the end part in the width direction has a height in the position of 5% of the width W from the end part in the width direction, i.e., in the position of 0.05 W from the end part in the width direction. In addition, the film thickness t2 has a film thickness and a maximum film thickness near the central part of the width W.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetic field sensor for converting an external magnetic field into an electric signal, and more particularly to a small-sized thin film geomagnetic sensor.

[0002]

2. Description of the Related Art As a method of detecting a minute magnetic field such as geomagnetism, a technique disclosed in, for example, Japanese Patent Application Laid-Open No. 8-75835 has attracted particular attention.
This publication discloses a magnetic impedance effect element in which a magnetic thin film is formed on a substrate and electrodes are provided at both ends in the longitudinal direction. This magneto-impedance effect is proposed by Professor Toshio Mori, one of the inventors in the publication, but in the short side (width) direction and circumferential direction of the rectangular or linear ferromagnetic material. It is characterized by providing magnetic anisotropy in advance. It utilizes the fact that the magnetic field from the longitudinal direction rotates the magnetization vector of the magnetic material, the magnetic permeability in the width direction increases, and the skin effect increases, thereby increasing the impedance of the ferromagnetic material. That is, a principle completely different from that of a so-called fluxgate magnetic field sensor is used.

[0003] Further, JP-A-8-330745 discloses that
A magnetic sensing element based on the magneto-impedance effect in which a magnetic thin film is formed on the entire upper surface of a rectangular substrate is disclosed.

Japanese Patent Application Laid-Open No. H11-109006 discloses a thin-film magnetic impedance sensor using a rectangular magnetic thin film, and a thin-film bias coil, a thin-film negative feedback coil, and a thin film.

[0005] Also, in a conventionally known orthogonal flux gate sensor utilizing the magnetic inductance effect, it is known that a high-frequency current is applied to a magnetic material similarly to the magneto-impedance effect sensor. For example, Patent No. 2
No. 617498 discloses a magnetic field sensor that applies a pulse current to a conductive strip-shaped ferromagnetic core and detects an external magnetic field with an electric signal from a conductor winding wound around the magnetic core. As the magnetic material to be used, an amorphous wire having zero magnetostriction or a strip-shaped amorphous ribbon is used.

[0006]

However, in these magnetic body direct high frequency excitation type magnetic field sensors, the expected output cannot be obtained even if the magnetic body is made thinner for the purpose of further miniaturization and higher integration. There was a problem. This is considered to be due to the fact that excitation is unlikely to occur effectively in the thin film because the thickness is small with respect to its width.

The present invention has been made in view of such circumstances, and an object of the present invention is to solve the above-mentioned conventional problems and to provide an extremely sensitive and small magnetic field sensor.

[0008]

In order to solve such a problem, the present invention has a substantially rectangular magnetic thin film,
In the magnetic field sensor in which a high-frequency current flows from both ends in the longitudinal direction of the magnetic thin film, the shape of the magnetic thin film in the cross section in the width direction is such that the film thickness near the center in the width direction is t2, and the film thickness t1 near the width direction end is t1. In this case, t2> t1 is satisfied.

In a preferred embodiment of the present invention, a film thickness t near the width end of the magnetic thin film in a cross section in the width direction.
1 and the film thickness t2 in the vicinity of the central portion is t2 / t1>
It is configured to satisfy the relationship of 1.2.

In a preferred embodiment of the present invention, a film thickness t in the vicinity of the width end in a width direction cross section of the magnetic thin film is provided.
1 and the film thickness t2 in the vicinity of the central portion is t2 / t1>
It is configured to satisfy the relationship of 1.5.

In a preferred embodiment of the present invention, the magnetic thin film has an average thickness t3 of 1 to 20 μm.

In a preferred embodiment of the present invention, the magnetic thin film is formed as a magnetic film formed by an electroplating method.

In a preferred embodiment of the present invention, the magnetic field sensor according to the present invention is configured as a magnetic field sensor using a magnetic impedance effect.

In a preferred embodiment of the present invention, the magnetic field sensor of the present invention is configured as a magnetic field sensor using a magnetic inductance effect.

In a preferred embodiment of the present invention, the width W of the magnetic thin film in a cross section in the width direction and the average film thickness t
3 is such that the relationship of W / t3> 2.0 is satisfied.

According to the present invention, the magnetic thin film (magnetic material) can be efficiently excited even with a low exciting current, although it is a small magnetic field sensor using a magnetic thin film, which can be formed collectively by a wafer process. It achieves low power consumption and high sensitivity at the same time.

[0017]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, specific embodiments of the present invention will be described in detail.

FIG. 1 is a perspective view schematically showing a preferred embodiment of a magnetic field sensor 1 of the present invention, and FIG. 2 is a sectional view taken along the line AA in FIG.

As shown in these figures, the magnetic field sensor of the present invention has magnetic thin films 11, 12, 13, and 14 made of a substantially rectangular ferromagnetic material on a substrate 5. A conductor coil 20 is wound around these magnetic thin films 11, 12, 13, and 14 in a lump as shown in the figure. In the case of the present embodiment, the four magnetic thin films are a set of two substantially rectangular magnetic thin films (11 and 12, 13 and 1).
4), they are connected in parallel and in series. That is, a current-carrying part 41 and a current-carrying part 42 which are integrally connected to each other are formed at one end of the magnetic thin films 11 and 12 and the magnetic thin films 13 and 14, respectively. Is provided with a conductive film 60 for folding the four core ends integrally connected. Energizing parts 41, 4
Numeral 2 is formed to supply a high-frequency current, and a high-frequency power supply 9 is connected as shown in the figure.

These magnetic thin films 11, 12, 13, 14
Is wound around, for example, a conductor coil 20 for detecting a magnetic field. The conductor coil 20 is usually formed as a thin-film coil 20, and electrode terminals 51, 5
2 are provided. And usually, the electrode terminals 51, 5
From 2, a wire bonder connects to a power supply and a signal processing unit provided outside. Of course, it is also possible to provide solder bumps on the electrode terminals 51 and 52 and mount them on a printed board or the like with the board surface facing up. Alternatively, it is also possible to form a sensor on a substrate having a through hole and mount the sensor surface on a printed circuit board or the like.

In a preferred embodiment of the present invention, a high-frequency current is supplied from the current-carrying portions 41 and 42 of the magnetic thin film, and the conductor coils wound around the ferromagnetic cores 11, 12, 13 and 14. 20 is applied to the electrode terminals 5
1 and 52 are detected as outputs.

As shown in FIG. 1, a plurality of ferromagnetic cores are combined, arranged in parallel with a predetermined gap therebetween, and a high-frequency current is applied to substantially both ends in the longitudinal direction of these magnetic thin films. A current-carrying part for forming the plurality of magnetic thin films substantially in parallel, or
In addition, by being configured to be connected in series, a higher output can be obtained because the influence of the demagnetizing field is reduced and the effective magnetic permeability of the magnetic thin film is increased, as compared with the case where one wide core is used. Further, since the magnetic domain structure of the magnetic thin film is also improved, an effect of reducing noise components is exhibited.

Incidentally, as shown in FIG.
The short sides at both ends of 1, 12, 13, and 14 each form an acute angle (shape at the tip),
Such a form is also regarded as one of substantially rectangular shapes. By forming the acute angle, compared with a so-called simple rectangular magnetic body, the magnetic domain structure is stabilized, and an effect of reducing noise can be expected. That is, the “substantially rectangular shape” in the present invention indicates a state in which the length L (FIG. 1) is longer than the width W (FIG. 2). Note that the length L when the acute angle is formed at the short side of the end of the magnetic thin film indicates the entire length. In one magnetic thin film, the length (L) with respect to the width (W)
It is preferable that the value of L / W, which is the ratio of, be 10 or more and 1000 or less, particularly 10 or more and 300 or less.

FIG. 3 shows one magnetic thin film 1 shown in FIG.
1 is an enlarged view of a cross section in the width direction of FIG.
Since the magnetic thin films 2, 13, and 14 have substantially the same form as the magnetic thin film 11, the magnetic thin film 11 will be described below as a representative example. The first feature of the present invention is that the width of the substantially rectangular magnetic thin film 11 in the width direction cross section of the magnetic thin film as shown in FIG.
1, when the film thickness near the center is t2, t2 / t1
> 1, preferably t2 / t1> 1.2, and more preferably t2 / t1> 1.5. Here, the film thickness t1 near the width end is defined by a height at a position 5% of the width W from the width end. That is, in the present invention, as shown in FIG. 3, the height at the position of 0.05 W from the width end is defined as t1.
The film thickness t2 is defined by the film thickness near the center of the width W and the maximum film thickness. If the value of t2 / t1 is 1 or less, there is a disadvantage that it becomes difficult to obtain efficient excitation of the magnetic material with a low excitation current. In other words, t1 = t2 in the magnetic thin film generally used in the related art, and only a lower output than the present invention can be obtained for the same exciting current. This is because the magnetic field generated by the exciting current hardly flows in the magnetic body. On the other hand, in the present invention, t2 / t
Since 1> 1, the magnetic field generated by the exciting current easily flows in the magnetic thin film.

In the present invention, t2 / t1> 1
Therefore, it is generally considered that the cross-sectional convex shape in which the film thickness is thicker at the center in the width direction is general, but in particular, the convex shape is limited as long as the numerical requirements of the present invention are satisfied. is not. The relationship between the width W and the average film thickness t3 is particularly significant when W / t3> 2.0, preferably W / t3> 10, and more preferably W / t3> 50. This is because the present invention has been basically made to solve the problems caused by the thin film. Here, the average film thickness t3 is defined as an average film thickness calculated based on the cross-sectional shape of the thin film. For example, the width of the cross section of the thin film shown in FIG. The heights in different widths are obtained, and the arithmetic average of these heights may be obtained.

FIGS. 4A to 4F show preferred specific examples of the cross section in the width direction of the magnetic thin film used in the present invention. FIG. 4A shows a form that is slightly close to a semicircle.
FIG. 4B is similar to FIG. 3, and FIG.
FIG. 4D is a form close to the modification of FIG. 4A, and FIG. 4D is a form in which an ellipse or a circle is made as close as possible. FIG. FIG. 4F shows a form in which the film is stopped and manufactured, and the films are stacked in a stepwise manner.

For comparison with the present invention, FIG.
Comparative examples are shown in FIGS. 0 (A) and (B). FIG.
In both (A) and (B), since the sectional shape does not satisfy the condition of t2 / t1> 1, the effect of the present invention is not exhibited.

The thickness of the magnetic thin film 11 of the present invention, particularly the average thickness t3, is preferably 1 to 20 μm.
If the film thickness is less than 1 μm, the resistance of the magnetic body becomes large, and the amount of electricity consumed to supply the exciting current increases. In the case of a magnetic field sensor using the magnetic impedance effect, the skin effect does not easily appear, and it is difficult to obtain an output. Further, the distribution of the magnetic field flowing through the magnetic thin film 11 (magnetic material) is poor, and the magnetic thin film is not effectively magnetized. Also,
If the film thickness exceeds 20 μm, it takes a long time to form the film, and the production cost increases. Further, the thin film process such as coil formation becomes difficult, and the yield decreases.

The magnetic thin film 11 of the present invention can be formed by a vacuum film forming method such as sputtering or vapor deposition, but is preferably formed by an electroplating method. That is, when forming a film by a pattern plating method using a photoresist, the film formation conditions, current density, stirring speed, temperature, and plating bath composition (metal ion concentration, additive concentration, conductive salt concentration, etc.) are selected. Thereby, for example, those having various cross-sectional forms shown in FIGS. 4A to 4F can be easily manufactured.

The frame plating method is a method of forming a plating film inside a photoresist wall as shown in FIG. That is, as shown in FIG.
A base conductive film 91 is formed thereon, and photoresist walls 95, 95 which function as a frame are formed with a predetermined space S by using a photoresist technique. Next, the magnetic thin film 11 is formed by plating and embedded in the space S (FIG. 5B).
5, 95 are removed (FIG. 5C). As a result, the magnetic thin film 11 having a sectional shape similar to that of FIGS.
Is formed.

According to such a film forming method, it is also possible to manufacture a form in which a part of the magnetic thin film is protruded largely on the photoresists 95, 95 as shown in FIG.

As shown in FIG. 7, in the step before forming the magnetic thin film, a gentle concave portion is formed on the surface of the underlying conductive film 91 by the underlying insulating layers 102 and 102 as shown in FIG. Frame plating resists 105, 105 may be formed at both ends, and then the magnetic thin film may be buried in the formed concave portion to form a magnetic thin film having an elliptical or nearly circular cross section. . The cross-sectional shape of the magnetic thin film shown in FIG. 7 substantially corresponds to the cross-sectional shape of FIG. And FIG.
If the film formation is stopped moderately before reaching the cross-sectional shape of (D), the form of FIG. 4E can be formed.

As described above, when the thickness of the magnetic layer near the width end in the width direction cross section of the magnetic thin film 11 is t1, and the thickness of the magnetic layer at the center is t2, the magnetic field of the present invention has a cross-sectional form where t2> t1. The sensor can be widely used as a magnetic field sensor having an operation mechanism in which a current flows in the longitudinal direction of a magnetic thin film (magnetic material) and the magnetic thin film is magnetized by a magnetic field generated by the current. According to the detection principle, the present invention can be applied to both (1) the case using the magnetic impedance effect and (2) the case using the magnetic inductance effect.

The magnetic field sensor of the present invention configured as described above not only can improve the excitation efficiency by directly energizing the magnetic thin film as described above, but also includes a coil wound around the magnetic thin film and the magnetic thin film. And the detection efficiency is improved. Further, even when the coil wound around the magnetic thin film is used not as a detection coil but as a bias magnetic field generating coil or a negative feedback magnetic field generating coil, it is possible to effectively generate a magnetic field. As a result, the current value required to apply the same magnetic field to the magnetic thin film can be reduced.

As the magnetic thin film, NiFe, NiFeP,
CoFe, CoNiFe, CoFeP, NiFeMo,
Various known magnetic materials such as FeZrN and FeN can be used. In particular, as a magnetic thin film for an MI (magnetic impedance) sensor, the anisotropic magnetic field Hk is 10 Oe.
A material of not less than 30 Oe or less, for example, a NiFeCo ternary alloy magnetic thin film and a CoFe binary alloy magnetic thin film are particularly preferable.

Further, as shown in FIG.
It is not necessary that the number be one, and another number or one may be used.

In the magnetic field sensor shown in FIG. 1, the conductor coil 20 used is preferably a thin film coil 20 formed based on a so-called thin film process. FIG.
The cross section of the thin film coil 20 is partially shown in FIG.
And the upper coil portion 25. In this case, insulating layers 71 and 72 are formed so as to surround the magnetic thin films in order to insulate them from the magnetic thin films 11, 12, 13, and 14. The conductor coil is not limited to the detection coil as described above, and may be used as a bias magnetic field generating coil or a negative feedback magnetic field generating coil.

It is to be noted that, when the thin film coil is formed as a thin film and the conductive portions 41 and 42 made of copper and the conductive film 60 for folding are formed at the same time, the manufacturing process is rationalized.

The gap between the adjacent magnetic thin films is about 0.1 to 50 μm.

In the magnetic field sensor of the present invention, a high-frequency current flows in the longitudinal direction of the magnetic thin films 11, 12, 13, and 14. The high-frequency current in the present invention is a general term for a current whose current value changes with time, and can be used for any waveform such as a sine wave, a rectangular wave, a sawtooth wave, and a pulse wave.

FIG. 8 shows another embodiment of the magnetic field sensor of the present invention, in particular, a modified example of the winding method of the conductor coil 20. According to this, for example, two magnetic thin films 11,
12, one conductor coil 20 is sequentially and continuously wound. By adopting such a winding method, for example, an effect that excitation noise is reduced is produced.

In the magnetic field sensor of the present invention, as shown in FIG. 2, it is preferable to provide a known organic and / or inorganic protective film 75 on the uppermost surface. Further, it is also possible to perform a resin sealing process like other electronic components. In this case, it is desirable to form a protective layer in advance as a stress relaxation layer with a resin different from the sealing resin before sealing the resin so that a large stress is not applied to the magnetic thin film.

It is also possible to combine two magnetic field sensors of the present invention to form a two-axis magnetic field sensor and to combine three magnetic field sensors to form a three-axis magnetic field sensor. At this time, the direction in which the current flows through the magnetic thin film constituting each sensor is orthogonal to each other. In the case of two axes, it is also possible to form an element portion on each of the front and back of one substrate, or to laminate two sensors on one substrate.

[0044]

The present invention will be described in more detail with reference to specific examples below. [Experimental Example I] (Examples I-1 to I-4, Comparative Examples I-1 to I-2)

A magnetic field sensor sample as shown in FIG. 1 was produced in the following manner.

Preparation of Specific Sample

A lower coil was formed by electroplating on a silicon wafer substrate having an oxide film on the surface.
In addition, the coil lead wire was produced at both ends when producing the lower coil to improve the yield. Next, a magnetic thin film (core) made of a NiFe plating film was formed on a lower insulating layer made of a thermosetting novolak resin by a pattern electroplating method while changing the current density as shown in Table 1 below while applying a magnetic field in the longitudinal direction. Were prepared in various ways.

The length L of the magnetic thin film (core) is 2 mm and the width W
Was 400 mm, and the film thicknesses t1 and t2 were as shown in Table 1 below. Note that the number of components of the magnetic thin film included in the manufactured sample is one. The average thickness t3 of the magnetic thin film is 4 μm.
m.

After forming the magnetic thin film (core), an upper coil was formed via an upper insulating layer. At the time of photoresist exposure of the upper coil, an auxiliary exposure mask was used because a distribution occurs in the resist film thickness. Finally, an insulating layer was formed as a protective layer to obtain a magnetic field sensor.

A sine waveform high frequency current having a frequency of 5 MHz was applied to the magnetic thin film core of the completed magnetic field sensor to determine an output value due to terrestrial magnetism (0.3 Oe), and converted to an output per 1T to compare various element samples. The measurement of t1 and t2 was performed by observing the cross section in the width direction of the magnetic thin film core with an electron microscope. The experimental results are shown in Table 1 below.

[0051]

[Table 1]

[Experimental Example II]

FIG. 9 shows a next preferred embodiment of the present invention.
The MI (magnetic impedance) sensor shown in FIG. That is, a lower coil c1 having a thickness of 4 μm was formed on a Corning 7059 glass substrate by electroplating.
And c2 were formed. The lower coils c1 and c2 are connected to the upper coils c11 and c22 in a later step, and form a 25-turn bias application coil (C1) and a negative feedback coil (C2), respectively.

The longitudinal direction of the lower coils c1 and c2 was arranged so as to be orthogonal to the longitudinal direction of the magnetic thin film 11. This is because the unevenness due to the lower coil affects the magnetic properties of the magnetic thin film 11, particularly the anisotropy. That is, the longitudinal direction of the lower coils c1 and c2 is
By making the magnetic thin film 11 perpendicular to the longitudinal direction, the anisotropy of the magnetic thin film 11 can be effectively imparted in the width direction. That is,
If the lower coils c1, c2 and the upper coils c11, c shown in FIG.
Consider a case where 22 is provided in reverse, that is, a case where the coils c11 and c22 that are not orthogonal to the magnetic thin film are below the magnetic thin film. Then, the anisotropy of the magnetic thin film is bent in the longitudinal direction of the coils c11 and c22.

When the lower coils c1 and c2 are formed, that is, before the magnetic thin film 11 is formed, the current-carrying units 60 and 60 for applying a current to the magnetic material are formed in advance. Next, a lower insulating layer (not shown) was formed on the lower coils c1 and c2 using a polyimide resist. Next, a NiFe plating film was formed as a magnetic thin film 11 in a pattern having a width of 20 μm and a length of 700 μm while applying a magnetic field in the width direction. As shown in Table 2 below, three types of magnetic thin films (magnetic materials) having different cross-sectional shapes were formed by varying the current density during film formation as shown in Table 2 below (Example II-1, Comparative Examples II-1, II-). 2). Next, an upper insulating layer (not shown) and upper coils c11 and c22 were formed, and an example sample II-1 and comparative example samples II-1 and II-2 as shown in Table 2 below were produced. Average thickness t3 of the magnetic thin film
Was 5 μm. When forming the upper coil, the conducting portions 60 for supplying electricity to the magnetic thin film 11 were formed at the same time. That is, the conducting portions 60 of the magnetic thin film 11
Was formed in a structure in which both the lower surface and the upper surface were covered with a conductor and sandwiched by the conductor. As a result, reliable energization can be guaranteed. The electrodes 53 and 54 and 55 and 56
Are energizing electrodes of the bias application coil (C1) and the negative feedback coil (C2), respectively.

The results are shown in Table 2 below.

[0057]

[Table 2]

[0058]

The effects of the present invention are clear from the above results. That is, the magnetic field sensor of the present invention has a substantially rectangular magnetic thin film, and has a mechanism for supplying a high-frequency current from both ends in the longitudinal direction of the magnetic thin film. The film thickness near the center in the width direction is t
2. When the film thickness t1 near the end in the width direction is set, t2> t1
Is achieved, the sensitivity is extremely high and the size can be reduced as compared with the conventional sensor. More specifically, not only can the excitation efficiency by directly energizing the magnetic thin film be improved, but also the magnetic coupling between the coil wound around the magnetic thin film and the magnetic thin film is improved, and the detection efficiency is also improved. . Further, even when the coil wound around the magnetic thin film is used not as a detection coil but as a bias magnetic field generating coil or a negative feedback magnetic field generating coil, it is possible to effectively generate a magnetic field. As a result, it is possible to reduce the current value required to apply the same magnetic field to the magnetic thin film.

[Brief description of the drawings]

FIG. 1 is a perspective view schematically showing a preferred example of a magnetic field sensor according to the present invention.

FIG. 2 is a sectional view taken along the line AA of FIG. 1;

FIG. 3 is an enlarged view of a cross section in the width direction of one magnetic thin film in FIG. 2;

4 (A) to 4 (F) are drawings showing preferred cross-sectional aspects of the magnetic thin film of the present invention.

FIGS. 5A to 5C are diagrams for explaining a frame plating method, which is an example of a preferable manufacturing method for forming a magnetic thin film of the present invention, with time.

FIG. 6 is a drawing for explaining an example of a preferred manufacturing method for forming a magnetic thin film of the present invention.

FIG. 7 is a drawing for explaining an example of a preferred manufacturing method for forming a magnetic thin film of the present invention.

FIG. 8 is a drawing schematically showing different embodiments of the magnetic field sensor of the present invention, in particular, a modified example of a method of winding a conductor coil.

FIG. 9 is a drawing schematically showing another embodiment of the magnetic field sensor of the present invention, in particular, an MI (magnetic impedance) sensor.

10 (A) and 10 (B) are drawings showing aspects of a cross section in the width direction of a magnetic thin film which is a comparative example, respectively.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Magnetic field sensor 5 ... Substrate 9 ... High frequency power supply 11, 12, 13, 14 ... Magnetic thin film 20 ... Conductor coil 41, 42 ... Conducting part 51, 52 ... Electrode terminal

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Toru Oikawa 1-13-1 Nihonbashi, Chuo-ku, Tokyo FDT term (reference) 2G017 AA01 AA16 AC09 AD42 AD51 AD63 AD65 BA03

Claims (8)

[Claims] 1. A magnetic field sensor having a substantially rectangular magnetic thin film and supplying a high-frequency current from both ends in the longitudinal direction of the magnetic thin film, wherein the shape of the magnetic thin film in a cross section in the width direction is in the vicinity of the center in the width direction. The magnetic field sensor satisfies t2> t1, where t2 is the thickness of the film and t1 is the thickness of the film near the end in the width direction. 2. A relationship between a film thickness t1 near the width end and a film thickness t2 near a center in a width direction cross section of the magnetic thin film satisfies a relationship of t2 / t1> 1.2. Item 2. The magnetic field sensor according to Item 1. 3. The relationship between the thickness t1 near the width end and the thickness t2 near the center in the width direction cross section of the magnetic thin film satisfies the relationship of t2 / t1> 1.5. Item 2. The magnetic field sensor according to Item 1. 4. An average thickness t3 of the magnetic thin film is 1 to 20.
The magnetic field sensor according to claim 1, wherein the magnetic field sensor has a thickness of μm. 5. The magnetic field sensor according to claim 1, wherein the magnetic thin film is a magnetic film formed by an electroplating method. 6. The magnetic field sensor according to claim 1, wherein the magnetic field sensor uses a magnetic impedance effect. 7. The magnetic field sensor according to claim 1, wherein the magnetic field sensor uses a magnetic inductance effect. 8. A width W in a cross section of the magnetic thin film in a width direction.
The magnetic field sensor according to any one of claims 1 to 7, wherein a relationship between the average thickness and the average film thickness t3 satisfies a relationship of W / t3> 2.0.