JP3290828B2 - Thin film inductance element and method of manufacturing the same - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a thin-film inductance element such as a planar inductor and a planar transformer, and a method of manufacturing the same.

[0002]

2. Description of the Related Art In recent years, the miniaturization of various electronic devices has been actively promoted, but the miniaturization of the power supply section of the electronic devices has been delayed in comparison. For this reason, the volume ratio of the power supply unit to the entire device is increasing. The miniaturization of electronic devices largely depends on the use of LSIs in various circuits. However, magnetic components such as inductors and transformers, which are indispensable for the power supply unit, have been delayed in such miniaturization and integration. Is the main cause of the increase in volume ratio.

[0003] In order to solve such a problem, a planar magnetic element in which a planar coil and a magnetic film are combined has been proposed, and studies for improving its performance have been made. The magnetic films used for these are required to have high magnetic permeability and low loss in a high frequency region of 1 MHz or more. In order to realize high permeability and low loss in a high frequency region, it is necessary to cover the magnetization process mainly by a rotational magnetization process. In addition, in order to obtain an ideal rotational magnetization process with flat frequency characteristics, it is necessary to perform hard axis excitation under uniform in-plane uniaxial magnetic anisotropy. In order to satisfy the values of the high-frequency magnetic permeability and the saturation magnetization required for the inductance element, it is necessary to set appropriate values.

Conventionally, in order to impart and control magnetic anisotropy to a magnetic film of a thin-film inductance element, heat treatment in a DC magnetic field, heat treatment in a rotating magnetic field, magnetic film patterning for anisotropy of strain, and the like have been proposed. Various methods have been tried. In addition to the anisotropy, there is a research example in which a thin film inductance element is attempted to be realized by isotropic treatment. For example, a method of laminating a plurality of magnetic films having different easy magnetization axis directions is being studied. However, when mass-producing thin-film inductance elements in practice, a simple and excellent controllability method is required. A method of inducing uniaxial magnetic anisotropy by applying heat treatment in a DC magnetic field to an appropriate soft magnetic film. Is considered the most suitable.

The above-mentioned heat treatment in a DC magnetic field is generally performed by maintaining a predetermined temperature while applying a constant DC magnetic field in parallel to the magnetic film surface. The relationship between the heat treatment temperature and heat treatment time and the magnetic anisotropy induced in the magnetic film is as follows:
Although it varies depending on the physical properties of the sample before the heat treatment, when the main cause of the anisotropy induction is a relatively general directional regular arrangement mechanism or a mechanism similar to the directional regular arrangement mechanism, usually, during the heat treatment, An easy axis is induced parallel to the magnetization vector direction.

In general, a coil layer used in a thin film inductance element has a spiral structure such as a circular or rectangular shape. However, a circular coil is difficult to take advantage of a magnetic film having uniaxial anisotropy. A combination of a square or rectangular rectangular spiral structure coil and a uniaxial magnetic anisotropic magnetic film is excellent as a high-frequency thin-film inductance element. The magnetic field generated by the conductor of the coil circulates around the cross section of the conductor, and in order to realize the above-described hard axis excitation, there is an easy axis of magnetization in a direction parallel to the conductor.
An arrangement in which a hard magnetization axis exists in a direction perpendicular to the conductor is ideal.

By the way, in the heat treatment in a DC magnetic field described above, when attention is paid to a certain inductance element,
The device is generally heat treated in an external magnetic field of uniform, ie, approximately the same magnitude and direction. For this reason, a uniform uniaxial magnetic anisotropy is imparted to the magnetic film in one element regardless of the location. However, as shown in FIGS. 8 and 9, when the magnetic films 1 and 2 having uniform uniaxial magnetic anisotropy are used and the coil 3 having a spiral structure is used, the coil 3 is formed over the entire area of one element. A structure having an easy axis of magnetization in the direction of the conductor cannot be realized, and the easy axis excitation is partially generated.
That is, in the region A of the magnetic films 1 and 2, hard axis excitation is performed, but in the region B, easy axis excitation is performed. For this reason, in order to eliminate or reduce the influence of easy axis excitation, patterning such that a magnetic film does not exist at a location where easy axis excitation occurs, or extreme use of the short spiral coil 3 as shown in FIG. Measures such as rectangularization are required. FIG.
Arrow M in FIG. 0 indicates the axis of easy magnetization. These measures for eliminating or reducing the influence of the easy axis excitation hinder the effective use of the magnetic flux generated from the coil and cause the process to be complicated.

Further, in the future, the integration of the power supply unit will advance, and integrated devices such as a one-chip power supply device including a thin-film inductance device will be formed on a wafer. The above inductance element may be required. In such a case, in order to reduce the magnetic coupling of the inductance elements, it is preferable that the directions of the inductance elements in the wafer plane are orthogonal to each other. Therefore, it is fully conceivable that the arrangement direction of the inductance elements is not one in the whole wafer but two or more. In this case, even if a rectangular rectangular coil with a coil pattern that facilitates effective use of the uniform uniaxial magnetic anisotropy of the magnetic film is adopted for each element, the entire wafer is heat-treated in a uniform external magnetic field. However, only a part of the inductance elements in the wafer can realize excellent high-frequency characteristics.

To avoid this, a method of dividing the wafer before the heat treatment in the magnetic field and performing the heat treatment in the magnetic field by using the same part in the direction of the inducance element as a unit can be considered, but the process becomes complicated and the productivity is reduced. And increase production costs.

[0010]

As described above, when a coil having a spiral structure is employed or a one-chip power supply element including a thin-film inductance element is formed on a wafer, a conventional magnetic field is applied in one direction. In a heat treatment in a magnetic field performed while applying a voltage, a structure having an easy axis of magnetization in the direction of the coil conductor can be realized only in a part of the magnetic film or a part of many elements, and is excellent in all directions or elements. This causes a problem that high frequency characteristics cannot be imparted.

For this reason, as a method of imparting and controlling uniaxial magnetic anisotropy to the magnetic film of a thin-film inductance element, an axis of easy magnetization is set in all directions or in parallel with the nearest coil conductor direction for many elements. In addition, there is a demand for a method for easily generating, and a magnetic film structure that can easily generate such an easy axis of magnetization has been desired.

SUMMARY OF THE INVENTION The present invention has been made to address such a problem, and a thin film inductance having a magnetic film capable of having an easy axis of magnetization in a direction parallel to a plurality of coil conductor directions. An object is to provide an element and a method for manufacturing the same.

[0013]

According to the present invention, there is provided a thin-film inductance element comprising a magnetic film and a coil disposed along the magnetic film, wherein the magnetic film has a film surface. And an average demagnetizing field in a direction substantially orthogonal to at least one current direction of the coil is equal to or greater than the anisotropic magnetic field of the magnetic film itself, and is substantially orthogonal to the direction of the average demagnetizing field. It is characterized by having an easy axis of magnetization in the direction.

Further, according to a method of manufacturing a thin-film inductance element of the present invention, a thin-film inductance element including a magnetic film and a coil disposed along the magnetic film is provided with an external magnetic field parallel to a film surface of the magnetic film. A method of manufacturing a thin-film inductance element having a step of heat-treating the magnetic film while applying, wherein an average demagnetizing field in a direction parallel to the film surface and in a direction substantially perpendicular to at least one current direction of the coil, A magnetic film having an anisotropic magnetic field at a heat treatment temperature or higher is used, and the magnetic film is heat-treated while the external magnetic field is set to be equal to or lower than the average demagnetizing field. Further, in the method for manufacturing a thin-film inductance element, the magnetic film is heat-treated while the external magnetic field is set to be equal to or more than the anisotropic magnetic field and equal to or less than the average demagnetizing field.

Hereinafter, the present invention will be described in detail.

The thin-film inductance element according to the present invention has a magnetic film having an average demagnetizing field in at least one direction parallel to the film surface and substantially perpendicular to the current direction of the nearest coil, which is equal to or larger than the anisotropic magnetic field. are doing.

[0017] Here, the average and demagnetization field H _d is referred to in the present invention, in a virtual cross-section which is substantially perpendicular to the current direction of the nearest coil of the magnetic film portion of interest, the demagnetizing field in the magnetic film It indicates the average value. This is different from a sphere or a spheroid in a magnetic film for a thin-film inductance element generally adopting a shape similar to a rectangular parallelepiped or a rectangular parallelepiped, and the demagnetizing field inside the magnetic film is a function of a place and is not uniform. That's why.

FIG. 1 schematically shows the relationship between the magnetic film 11 and the coil conductor 12 realized inside the thin-film inductance element. In FIG. 1, the in-plane X direction corresponds to the coil conductor 1.
2 is a direction parallel to the current direction x. Here, the magnetic film 1
If the lengths a, b, and t of each side satisfy a> b >> t, the in-plane Y direction, that is, the nearest coil conductor layer 12
The average demagnetizing field is expected to be largest in a direction substantially orthogonal to the current direction x. Therefore, the magnetic film 1 is parallel to the Y direction.
Maximum average demagnetization average parallel to the Y direction generated when magnetizes 1 until saturation magnetization demagnetization field H _d is the plane (H _d)
^max . That is, the average demagnetizing field H defined in the present invention
_d (the average demagnetizing field in a direction substantially orthogonal to the current direction of the nearest coil) is the maximum in-plane average demagnetizing field (H _d ) ^max . The above-described average demagnetizing field H _d means the value of the magnetic field at the heat treatment temperature during the heat treatment. For example, if the heat treatment temperature is 700 K, (H _d ) ^max is
Demagnetizing field generated by magnetization at 700K.

In FIG. 1, the magnetic film 11 is actually shown as having a finite size of a × b × t.
The coil conductor 12 is a conceptual diagram for expressing the direction of the current flowing through the coil.
The number and length of 2 are not limited to FIG.

Further, intrinsic anisotropy field H _k of the magnetic film as defined in the present invention may be any average less demagnetization field H _d described above in at least the heat treatment temperature. That is,
The above-mentioned anisotropic magnetic field H _k indicates an anisotropic magnetic field at least when the sample is at 700 K, if the heat treatment temperature is 700 K. In other words, the above-described average demagnetizing field H _d
It is preferable to appropriately set the heat treatment temperature at which is equal to or higher than the anisotropic magnetic field H _k . However, considering that the uniaxial magnetic anisotropy is effectively induced by heat treatment, the average demagnetizing field H
_d it is preferred that the intrinsic anisotropy field H _k or more at temperatures above 553 K. Here, the anisotropy field H _k of a general magnetic material becomes larger at room temperature as compared for example when more than the heat treatment temperature 553 K. Therefore, the average demagnetization field H _d is equal to the anisotropy field H _k or more at room temperature, satisfying the basic structure of the normal present invention. Further, by using the magnetic film also satisfies at room temperature the average relationship between the demagnetizing field H _d and the anisotropy field H _k, most in order to be able to stabilize the direction of the magnetic moment from the start to the end of the heat treatment It is effective.

The magnetic film of the present invention has an anisotropic magnetic field value of 800 A / m or more at least at room temperature, and is distinguished from an isotropic magnetic film.

The magnetic film in the thin-film inductance element of the present invention is a material capable of inducing uniaxial magnetic anisotropy by heat treatment in a magnetic field, for example, an amorphous magnetic film composed of a multi-phase amorphous Fe-Co-BC. Is used. This multi-phase amorphous Fe-Co-
BC-based magnetic materials are known materials from which good soft magnetism can be obtained. However, the magnetic film material is not limited to the multi-phase amorphous Fe-Co-BC-based magnetic material.
A system magnetic material is also preferably used.

[0023] In the present invention, to determine the heat treatment temperature T _a which corresponds to the magnitude of the intrinsic uniaxial anisotropy to be induced first. Needless to say, the anisotropic magnetic field felt by the magnetic film when finally driven as an inductance element at room temperature is the sum of the intrinsic induced uniaxial magnetic anisotropy and the shape anisotropy of the magnetic film. after determining the anisotropy field during the determination of the heat treatment temperature T _a is required as the magnetic film constituting the inductance element, in consideration of the influence of the magnetic field due to the shape anisotropy, essential uniaxial required What is necessary is just to evaluate the magnitude of magnetic anisotropy.

[0024] determining the heat treatment temperature T _a, the essential anisotropy field H _k induced during the heat treatment is determined as the physical properties of the magnetic film. Therefore, the maximum average demagnetizing field (H
_d) ^max determines the magnetic film shape not less than intrinsic anisotropy field H _k, and patterned. The azimuth relationship with the nearest coil is patterned such that the direction in which (H _d ) ^max is obtained on the inner surface of the film is substantially perpendicular to the direction of the current flowing through the coil conductor.

For example, taking FIG. 1 as an example, the shape of the magnetic film 11 is a rectangular parallelepiped, and a> b among the lengths a, b, and t of each side.
By patterning the magnetic film 11 so as to satisfy the following inequality, the direction Y becomes a direction in which (H _d ) ^max is obtained in the film plane, and is substantially orthogonal to the direction of the current flowing through the coil conductor 12. In order to satisfy the relationship of (H _d ) ^max ≧ H _k ,
Each side a, b of the magnetic film parallel to the thickness t of the magnetic film 11 and the film surface
The ratio may be adjusted.

Here, as shown in FIG. 1, the saturation magnetization I
_When the magnetic film 11 of s has a rectangular parallelepiped shape of a × b × t, the maximum average demagnetizing field (H _d ) ^max in the Y direction can be calculated by approximating a flat elliptic plate by the following equation (1). The average demagnetizing field of the present invention indicates the value calculated by the equation (1).

[0027]

(Equation 1) Therefore, if the shape of the magnetic film is limited to a rectangular parallelepiped, if the lengths of the sides a, b, and t of the magnetic film 11 are determined so that (H _d ) ^max obtained by the expression (1) does not become smaller than H _k. This satisfies the conditions of the present invention.

In the thin-film inductance element according to the present invention, the magnetic film has the above-mentioned relationship ((H _d )) between (H _d ) ^max and H _k.
^max ≧ H _k ) and magnetization in a direction substantially perpendicular to the direction in which (H _d ) ^max is determined, that is, in the example of FIG. 1, in a direction X substantially parallel to the current direction x of the nearest coil conductor 12. It has an easy axis (indicated by an arrow M in the figure).
In other words, by satisfying the relationship of (H _d ) ^max ≧ H _k , the easy axis of magnetization can be easily provided in a direction substantially parallel to the current direction of the nearest coil.

(H _d ) ^max and H in the magnetic film of the present invention
The relationship with _k is such that if the average demagnetizing field (H _d ) ^{max in} a direction substantially perpendicular to at least one of the current directions of the coils arranged along the magnetic film is satisfied, the configuration of the present invention is satisfied. Similarly, if the easy axis is provided in parallel to at least one of the coil current directions with respect to the direction in which the average demagnetizing field (H _d ) ^max is defined, the present invention is also applicable. However, when a rectangular spiral coil is used, for example, the average demagnetizing field (H _d ) ^{max in} a direction substantially perpendicular to all the current directions is (H _d ) ^max It is preferable to satisfy the relationship of ≧ H _k , whereby the axis of easy magnetization can be easily provided in all directions substantially parallel to the current direction of the nearest coil.

That is, in a more preferred form of the thin film inductance element of the present invention, the magnetic film is parallel to the film surface,
An average demagnetizing field (H _d ) ^{max in} a direction substantially orthogonal to two or more current directions (more preferably, all current directions) of the coil is equal to or more than the anisotropic magnetic field H _k of the magnetic film itself. Along with the direction of the average demagnetizing field 2
It can be said that it has an axis of easy magnetization in one or more directions (more preferably, all directions).

Next, a specific method for imparting uniaxial magnetic anisotropy will be described.

First, the temperature of the magnetic film (including the one having a thin-film inductance element structure) that satisfies the relationship between (H _d ) ^max and H _k is set to the above-described heat treatment temperature T _a.
, An external magnetic field _Hex is applied in parallel to the film surface of the magnetic film. When there are a plurality of current directions of the coil conductor, the external magnetic field _Hex is sequentially applied according to each direction. At this time, the application of a plurality of magnetic fields is not simultaneous, and the magnetic field in the next direction is applied again after a predetermined time has elapsed after applying the magnetic field in one direction. The processing time is determined in consideration of the reaction speed of anisotropic magnetic field induction, which is a physical property of the magnetic film. The magnitude of the applied external magnetic field H _ex is not necessarily limited, but as will be described later, (H _d ) ^max ≧ H
_ex is preferably satisfied, and (H _d ) ^max ≧ H
it is most effective to meet the _ex ≧ H _k. External magnetic field H
The magnitude of _ex may vary depending on the direction, and between the heat treatment in the magnetic field in the first direction and the heat treatment in the magnetic field in the second direction, the sample temperature is returned to room temperature, and the temperature is raised again. May be accompanied by a temperature change.

The heat treatment in a magnetic field involving the application of a magnetic field in a plurality of directions will be described with reference to FIGS. 2A and 2B are sectional views showing the configuration of the thin-film inductance element. FIG. 3A shows the first magnetic film 21, FIG. 3B shows a rectangular spiral coil conductor 22, and FIG. Second
FIG. 4 is a view schematically showing a magnetic film 23 of FIG. As shown in FIG. 3, when the rectangular spiral coil conductor 22 is used, the direction in which the current flows differs depending on the location, and there are a region C and a region F which flow in parallel in the directions c and d.

Therefore, first, as a first heat treatment in a magnetic field,
Heat treatment in a magnetic field is performed by applying an external magnetic field parallel to the direction c. This first magnetic field heat treatment allows the magnetic films 21 and 2
An easy axis of magnetization substantially parallel to the current direction of the coil conductor 22 closest to the third region C is formed. This is because, in any direction relative to the intrinsic anisotropy of the magnetization easy axis is a direction c before the heat treatment, since the H _k is (H _d) is not greater than the ^max, essential Since the component that is not parallel to the direction c of the anisotropic magnetic field is offset by (H _d ) ^max , the magnetization vector during the heat treatment in the magnetic field cannot be orthogonal to the direction c, and the direction of the magnetization vector in the region C Becomes substantially parallel to the direction c. In particular, the external magnetic field H _ex is if satisfy H _ex ≧ H _k, parallelism of direction and direction c of the magnetization vector in the region C is improved.

On the other hand, at the time of the first heat treatment in the magnetic field, a magnetic field is applied to the region D of the magnetic films 21 and 23 at right angles to the current direction of the coil conductor 22 closest thereto. But H
Since _k is (H _d) is not greater than the ^max, the sum of at least H _k component parallel to the direction c of the H _ex is (H _d) unless larger than ^max, area in a direction parallel to the direction c D
Is not oriented. Therefore, in consideration of the microscopic dispersion of the direction of the intrinsic anisotropic magnetic field before the heat treatment in the first magnetic field, the direction d is almost parallel to the current direction of the coil conductor 22 in most cases. The magnetization vector is oriented in the direction. Therefore, an easy axis of magnetization substantially parallel to the direction d is provided. This effect is obtained when the applied magnetic field _Hex is ( _Hd ) ^max.
This is remarkable when the relationship of ≧ H _ex is satisfied. Therefore, the magnitude of the applied magnetic field H _ex is (H _d ) ^max ≧ H _{ex with} respect to the intrinsic anisotropic magnetic field H _k and the maximum average demagnetizing field (H _d ) ^max .
It is preferable to satisfy the relationship of ≧ H _k .

In the second heat treatment in a magnetic field, the heat treatment is performed by applying an external magnetic field parallel to the direction d. Therefore, the outline of the phenomenon occurring in the region C and the outline of the phenomenon occurring in the region D are opposite to those of the first heat treatment in a magnetic field. What is different is the essential easy axis direction before the heat treatment in the second magnetic field. Each of the regions C and D sets the essential easy axis direction in a direction substantially parallel to the current direction of the nearest coil conductor 22. have. Therefore, in the region C, even if _Hex ^{equal to} or more than ( _Hd ) ^max is applied, a component parallel to the direction d of the magnetization vector hardly occurs. In area D,
Since an intrinsic anisotropic easy axis substantially parallel to the direction d is generated from the beginning, the parallelism between the intrinsic anisotropic easy axis and the direction d by an external magnetic field parallel to the direction d. Is more improved. For the same reason as the first heat treatment in a magnetic field, the second
(H _d ) ^max ≧ H _ex ≧ H _k
It is most preferred to apply an external magnetic field H _ex satisfying a relationship.

The sample subjected to the above-described first and second heat treatments in a magnetic field has an intrinsic magnetization in a direction substantially parallel to the current direction of the coil conductor 22 in the vicinity of both the regions C and D of the magnetic films 21 and 23. An easy axis is provided. Furthermore, if necessary, reduction of in-plane uniaxial magnetic anisotropy before heat treatment in a magnetic field,
By further repeating the heat treatment in a magnetic field according to the present invention, a magnetic film having an easy axis of magnetization parallel to the current direction of the nearest coil conductor in various directions in practice is obtained.

As described above, the thin-film inductance element according to the present invention is provided with at least one current direction of the coil which is parallel to the film surface of the magnetic film which is in direct contact with the coil or indirectly via the insulator layer or the like. The average demagnetizing field (H _d ) ^{max in} a direction substantially perpendicular to the current, more preferably the average demagnetizing field (H _d ) ^{max in} a direction substantially perpendicular to all the current directions is an essential anisotropic magnetic field H _k The magnetic film described above is used. Since such a magnetic film is suitable for giving an easy axis of magnetization parallel to the current direction of the nearest coil conductor by heat treatment in a magnetic field, it has excellent high-frequency magnetic permeability. In addition, a thin-film inductance element utilizing the rotational magnetization process of the magnetic film to the maximum extent can be realized at low cost by simple heat treatment in a magnetic field.

[0039]

Embodiments of the present invention will be described below.

Example Under the conditions shown in Table 1, an Fe-Co-BC-based multi-phase amorphous magnetic film was formed. An upper protective film made of SiO ₂ was formed on the Fe-Co-BC-based multiphase amorphous magnetic film immediately after the film formation. After forming the upper protective film, the magnetic film was patterned by a lift-off method using a wet process using phosphoric acid as a main etchant. Immediately before the formation of the Fe-Co-BC-based multi-phase amorphous magnetic film, target pre-sputtering and substrate etching were performed.

[0041]

[Table 1] A preliminary experiment before making the above-described patterned magnetic film, Fe-Co-BC system saturation magnetization I _s temperature dependence and the temperature change of the intrinsic uniaxial anisotropy of the multi-phase amorphous magnetic film Data collected. The heat treatment temperature in the magnetic field was set to 593K. FIG.
As shown in the figure, the saturation magnetization of the magnetic film at room temperature was 1.6 T, but was 1.3 T at 593K. The anisotropic magnetic field H _k of the essential uniaxial magnetic anisotropy was 980 A / m by heat treatment in a DC magnetic field of 593 K as shown in FIG. However, since the anisotropic magnetic field H _k is a value measured at room temperature after heat treatment at 593 _K , the anisotropic magnetic field at 593 _K actually decreases below 980 A / m. The decrease in saturation magnetization with increasing temperature shown in FIG. 4 supports this estimate. Therefore, the value of the applied magnetic field _Hex during the heat treatment was set to 1000 A / m. This setting is H _ex ≧
_Hk is satisfied. Further, (H _d ) ^max ≧ H _ex
In order to satisfy the above, referring to the above-mentioned equation (1), the pattern width of the magnetic film, ie, FIG.
The length corresponding to (b) was set to 400 μm. FIG.
The length corresponding to a was 5000 μm. (H _d ) ^max during the heat treatment in this shape is 1060 A / m from the equation (1). Based on each of these lengths, as shown in FIG.
The e-Co-BC-based multi-phase amorphous magnetic film (thickness: 2 μm) was patterned in a square shape with a pattern width b of 400 μm and a side length a of 5000 μm. Thus, a magnetic film 31 satisfying the conditions of the present invention was obtained.

On the other hand, as a comparative example with the present invention, a magnetic film 32 having a pattern shape shown in FIG. 7 was manufactured by the same process as in the above embodiment. The magnetic film 32 according to the comparative example has a thickness of 2 μm, but a length corresponding to FIG.
And the maximum average demagnetizing field (H _d ) ^max (= 556A /
m) is smaller than the intrinsic anisotropic magnetic field H _k and does not satisfy the conditions of the present invention.

Each of the patterned magnetic films according to the above-described Examples and Comparative Examples was subjected to a heat treatment in a DC magnetic field in a vacuum. The ultimate vacuum was 6.3 × 10 ⁻⁵ Pa. The first heat treatment in a magnetic field was performed by maintaining a temperature of 593 K for 7200 seconds while applying a DC magnetic field of 1000 A / m in parallel to the direction e shown in FIGS. Subsequently, as a second heat treatment in a magnetic field, a DC magnetic field of 1000 A / m was applied in parallel to the direction f shown in FIGS.

The magnetization curves of the patterned magnetic films 31 and 32 after the heat treatment in the DC magnetic field were calculated from the polarization of the surface reflection at each side of the regions E and F of each magnetic film using a micro-Kerr effect measuring device. Were determined. The diameter of the surface to be measured is about 3μ
m. As a result, the region E of the magnetic film 31 according to the example is
It was confirmed that an easy axis of magnetization was generated parallel to the direction e and parallel to the direction f in the region F. The anisotropic magnetic field in the region E and the region F of the magnetic film 31 according to the example matched within the range of the measurement accuracy, and was about 2000 A / m. The anisotropic magnetic field is due to both the shape anisotropy of the patterned magnetic film and the intrinsic anisotropic magnetic field of the magnetic film.

On the other hand, in the magnetic film 32 according to the comparative example, it was confirmed that both the regions E and F had an easy axis of magnetization parallel to the direction f. Anisotropic magnetic field of area E is about 600A
/ m, and the anisotropic magnetic field in the region F was about 1300 A / m.

As described above, the magnetic film 31 according to the embodiment
In the above, after the heat treatment in a predetermined DC magnetic field, an easy axis of magnetization parallel to each side of the magnetic film pattern is given, and the magnetization of the hard axis by the magnetic field generated by the short spiral coil can be used for the entire axis of the magnetic film 31. It was confirmed that a magnetic anisotropic structure was obtained. On the other hand, in the magnetic film 32 according to the comparative example,
Uniaxial magnetic anisotropy in which the direction of the axis of easy magnetization after heat treatment is perpendicular to the direction parallel to the side of the magnetic film pattern depending on the region, and the magnetization of the entire magnetic film cannot be achieved with a short spiral coil. It was found that a sexual structure occurred.

Next, a thin film inductor having the structure shown in FIG. 2 was manufactured using the magnetic film 31 according to the above-described embodiment. Similarly, a thin film inductor was manufactured using the magnetic film 32 according to the comparative example. When the frequency characteristics of the inductance value of each of these thin film inductors were measured and evaluated, the thin film inductor according to the example showed that the inductance value at 13 MHz was within 1 dB compared to 1 MHz, and the quality factor was lower.
In contrast to 10 or more up to 13MHz, the thin film inductor of the comparative example has an inductance value of 1MHz at 13MHz.
-6dB or more, and the quality factor is 5 at 13MHz.
It was below.

As described above, by using the magnetic film having the uniaxial magnetic anisotropic structure in which the hard axis excitation by the magnetic field generated by the short spiral coil can be used in all regions,
A simple heat treatment makes it possible to realize a thin-film inductance element exhibiting excellent frequency characteristics and low loss.

[0049]

As described above, according to the present invention,
A thin film inductance element with excellent high-frequency characteristics that makes use of the rotational magnetization process of the magnetic film because it is possible to provide an easy axis of magnetization to the magnetic film in a direction parallel to the directions of the coil conductors by a simple process. Can be provided.

[Brief description of the drawings]

FIG. 1 is a diagram schematically showing a relationship between a structure of a magnetic film and an essential anisotropic magnetic field of the magnetic film in the present invention.

FIG. 2 is a cross-sectional view illustrating one configuration example of the thin-film inductance element of the present invention.

FIG. 3 is a diagram for explaining a direction of an applied magnetic field and a direction of an easy axis of magnetization in the thin-film inductance element of the present invention.

FIG. 4 is a diagram showing temperature dependence of saturation magnetization of a magnetic film according to an example of the present invention.

FIG. 5 is a diagram showing the temperature dependence of the anisotropic magnetic field of the intrinsic uniaxial magnetic anisotropy of the magnetic film according to the embodiment of the present invention.

FIG. 6 is a view showing a pattern shape of a magnetic film according to an embodiment of the present invention.

FIG. 7 is a diagram showing a pattern shape of a magnetic film according to a comparative example.

FIG. 8 is a cross-sectional view showing one configuration example of a conventional thin-film inductance element.

FIG. 9 is a diagram for explaining a direction of an applied magnetic field and a direction of an easy axis of magnetization in a conventional thin-film inductance element.

FIG. 10 is a diagram illustrating a configuration example of a thin-film inductor employing a rectangular spiral coil.

[Explanation of symbols]

 11, 21, 23: Magnetic film 12, 22: Coil conductor 31: Patterned magnetic film

────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-5-326260 (JP, A) JP-A-4-372104 (JP, A) JP-A-4-221812 (JP, A) 13256 (JP, A) (58) Field surveyed (Int. Cl. ⁷ , DB name) H01F 17/00-17/08 H01F 41/00-41/10

Claims (3)

(57) [Claims] 1. A thin-film inductance element comprising a magnetic film and a coil arranged along the magnetic film, wherein the magnetic film is parallel to the film surface and in at least one current direction of the coil. The thin film inductance, wherein an average demagnetizing field in a direction substantially perpendicular to the magnetic film is equal to or more than the anisotropic magnetic field of the magnetic film itself, and has an easy axis of magnetization in a direction substantially perpendicular to the direction of the average demagnetizing field. element. 2. A step of heat-treating the magnetic film while applying an external magnetic field in parallel to the film surface of the magnetic film of a thin-film inductance element having a magnetic film and a coil arranged along the magnetic film. Wherein the average demagnetizing field in a direction parallel to the film surface and substantially perpendicular to at least one current direction of the coil is not less than an anisotropic magnetic field at a heat treatment temperature. Using a membrane,
A method for manufacturing a thin-film inductance element, comprising: performing a heat treatment on the magnetic film while setting the external magnetic field to be equal to or less than the average demagnetizing field. 3. The method according to claim 2, wherein the magnetic film is heat-treated while setting the external magnetic field to be equal to or higher than the anisotropic magnetic field and equal to or lower than the average demagnetizing field.