JPH09256117A - Iron-base soft-magnetic alloy, and thin magnetic element using same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a soft-magnetic alloy, having high specific resistivity required of magnetic materials for, e.g. high frequency use and excellent in soft magnetism while maintaining high saturation magnetic flux density and low coercive force, and also to provide a thin magnetic element using this alloy. SOLUTION: This alloy is constituted essentially of crystal phases of <=30nm average crystalline grain size, composed essentially of Fe and having body- centered cubic structure, and amorphous phases surrounding the crystalline phases. Further, the amorphous phases are composed essentially of element M (one or >=2 elements selected from Ti, Zr, Hf, Nb, Ta, Mo, W, and rare earth elements), element T (either or both of B and C), O, and the oxide of the element M or the element T. Further, the specific resistivity of the amorphous phases is regulated so that it is higher than the specific resistivity of the crystal phases.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an Fe-based soft magnetic alloy suitable for magnetic elements such as magnetic head cores, thin film inductors, thin film transformers and switching elements, and a thin magnetic element using the same.

[0002]

2. Description of the Related Art With the miniaturization and high performance of magnetic elements, a soft magnetic material having a high magnetic permeability at a frequency of several 100 MHz or more, especially a high saturation magnetic flux density of 5 kG (0.5 T) or more, and a high specific resistance have been obtained. What has a low coercive force is required. Above all, a transformer having a high specific resistance is particularly required. As a magnetic material having a high saturation magnetic flux density, Fe or an alloy containing Fe as a main component is well known. However, when a magnetic film of these alloys is formed by a film forming technique such as a sputtering method, the saturation magnetic flux density is high. However, it was difficult to obtain good soft magnetic properties because the coercive force was large and the specific resistance was small.

[0003]

Further, one of the causes of the decrease in the magnetic permeability in the high frequency band is the loss due to the generation of eddy currents. Therefore, in order to prevent the eddy current loss that is one of the causes of the decrease in the high frequency magnetic permeability, it is desired to reduce the film thickness and the resistance of the thin film. However, it is very difficult to increase the specific resistance while maintaining the magnetic characteristics, and the specific resistance of the alloy-based soft magnetic thin film such as sendust is as small as several tens to hundreds of tens of μΩcm, and the saturation magnetic flux of at least 0.5T or more There is a demand for a thin film of a soft magnetic alloy having a high specific resistance while ensuring the density. When an alloy is obtained as a thin film, it is more difficult to obtain good soft magnetic properties due to the influence of magnetostriction and the like.

The present invention has been made to solve the above-mentioned problems, and has a high specific resistance as a magnetic material for high frequencies while maintaining a high saturation magnetic flux density and a low coercive force.
Moreover, it is an object of the present invention to provide a soft magnetic alloy having excellent soft magnetism and a thin magnetic element using the same.

[0005]

The soft magnetic alloy according to claim 1 comprises a crystalline phase having a body-centered cubic structure containing Fe as a main component and having an average crystal grain size of 30 nm or less, and an amorphous phase surrounding them. The main component of the amorphous phase is Ti, Zr,
Of one or more elements M selected from Hf, Nb, Ta, Mo, W and rare earth elements, one or two elements T of B and C, O, and elements M or T An oxide is a main component, and the resistivity of the amorphous phase is higher than that of the crystalline phase. According to the invention of claim 2, the Fe-based soft magnetic alloy is represented by the following composition formula. Fe _x M _y O _z
T _w However, x, y, z, and w, which indicate the composition ratio, are at% and 50 ≦ x
≦ 75, 5 ≦ y ≦ 30, 15 ≦ z ≦ 25, 0 <w ≦ 5, 1
The relation of 5 ≦ z + w ≦ 30 is satisfied. In the invention according to claim 3, w representing the composition ratio is 0.3 ≦ w ≦ 3.
The range is 0.

According to a fourth aspect of the present invention, a spiral planar coil, an insulating film, and a magnetic film of a soft magnetic alloy are laminated on a substrate, and the composition film Fe _{x is used} as the magnetic film of the soft magnetic alloy.
M _y O _z T _w , M is Ti, Zr, Hf, Nb,
Ta, Mo, W, and one or more elements selected from rare earth elements, T represents one or two of B and C, and the composition ratio x, y, z, w is at%. , 50 ≦ x ≦
75, 5 ≦ y ≦ 30, 15 ≦ z ≦ 25, 0 <w ≦ 5, 15
The magnetic film satisfies the relationship of ≦ z + w ≦ 30.

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION The soft magnetic alloy according to the present invention is Fe alloy.
Average grain size 30 having a body-centered cubic structure containing
mainly composed of a crystalline phase of nm or less and an amorphous phase surrounding the crystalline phase, and the amorphous phase is composed of Ti, Zr, Hf, N
one or more elements M selected from b, Ta, Mo, W and rare earth elements, and one or two of B and C
The seeds consist mainly of the elements T and O, and the oxide of the element M or the element T, and the resistivity of this amorphous phase is higher than that of the crystalline phase. In the soft magnetic alloy of the present invention, Fe is a main component and is an element responsible for magnetism. In order to obtain a high saturation magnetic flux density, more Fe is more preferable, but if it is 75 at% or more, other additive components are reduced and the specific resistance is reduced. On the other hand, when Fe is less than the range of the present invention, the specific resistance can be increased, but the saturation magnetic flux density decreases. From the above relationship, the Fe content has a saturation magnetic flux density of 0.1.
50-75 at in order to achieve 5T (tesla) or more
%, In order to make the saturation magnetic flux density 1T or more, 60 to 7
The range of 5 at% is more preferable.

Rare earth elements (ie, Sc, Y, or La, Ce, Pr, Nd, which belong to Group 3A of the periodic table,
Pm, Sm, Eu, Gd, Td, Dy, Ho, Er, T
lanthanoids such as m, Yb, and Lu), and Ti,
M, which represents one or more elements of the 4A group, 5A group, and 6A group of the periodic table including Zr, Hf, V, Nb, Ta and W, is necessary for obtaining soft magnetic properties. Is. These easily combine with oxygen, and when they combine, they form an oxide in an amorphous material. The specific resistance can be increased by adjusting the content of this oxide. The amorphous phase is mainly composed of the element M and an oxide of B or C which will be described later. In addition to these oxides, the elements M, B and C are also included.
Alternatively, it contains a small amount of Fe.

Next, O must be 15 at% or more, and 1
If it is less than 5 at%, a high specific resistance of 300 μΩcm or more cannot be obtained, but if it exceeds 25 at%, a high saturation magnetic flux density of 0.5 T or more cannot be obtained. Furthermore, B, C
If the content of T, which represents one or two of the above, in excess of 6 at%, a saturation magnetic flux density of 0.5 T or more cannot be obtained.
A content of at% or less is preferable. Also, 300 μΩcm
In order to reliably obtain the above specific resistance in a wide composition range,
The range of 0.3 to 3.0 at% is preferable. Next, when the value of O + T is less than 15 at%, a high specific resistance cannot be obtained. Also, if it exceeds 30 at%, 0.5
A saturation magnetic flux density of T or more cannot be obtained. Also, 15 to 30
When it is out of the range of at%, it becomes difficult to obtain a bccFe + amorphous structure. By appropriately setting the value of O + T, it is possible to increase the Fe concentration and increase the saturation magnetic flux density while maintaining the resistance value high. On the other hand, within the composition range of the present invention, 320 to 229110 μΩ
It is possible to obtain a high specific resistance in the range of cm, and it is possible to reduce eddy current loss by increasing the specific resistance, suppress a decrease in high frequency magnetic permeability, and improve high frequency characteristics.

Next, in the alloy of the present invention,
By performing the heat treatment at 600 ° C., excellent soft magnetic characteristics can be obtained in a state where the internal stress of the alloy film is removed. That is, if the soft magnetic alloy having the above composition is heat-treated at a predetermined temperature of 300 to 600 ° C., the coercive force and the specific resistance are adjusted while the saturation magnetic flux density is increased or maintained at a high value. can do. Therefore, by appropriately setting the heat treatment temperature, it is possible to obtain a soft magnetic alloy having a high saturation magnetic flux density and a coercive force and a specific resistance value depending on the application.

To form a magnetic film made of an alloy having the above composition, the alloy film is formed by a thin film forming technique such as sputtering or vapor deposition. As a sputtering device, RF bipolar sputtering, D
Existing ones such as C sputter, magnetron sputter, tripolar sputter, ion beam sputter, and facing target sputter can be used. O in the soft magnetic alloy film
As a method of adding (oxygen), reactive sputtering is effective in which sputtering is performed in a (Ar + O ₂ ) mixed gas atmosphere in which O ₂ gas is mixed in an inert gas such as Ar. It is also possible to manufacture it in an inert gas such as Ar using a composite target in which various pellets of oxides of rare earth elements or the like are arranged on the Fe target.

Further, in the structure of the soft magnetic alloy, it is preferable that a part of the microcrystalline phase of bcc Fe is contained and the rest is an amorphous phase. If the crystal grain size of the microcrystalline phase is large and the proportion of the crystalline phase is high, the resistivity is relatively low, and if the amorphous phase containing a large amount of oxygen occupies most of the structure, the resistivity tends to be high. There is. On the other hand, if a spiral planar coil is formed on a substrate using a magnetic film of a soft magnetic alloy having the above-mentioned excellent magnetic characteristics and specific resistance, a thin (planar) magnetic layer that exhibits excellent magnetic characteristics. The device is obtained.

1A and 1B show a first structural example of an inductor (thin magnetic element) formed by using a magnetic film of a soft magnetic alloy having the above composition. In the inductor B of this example, spiral planar coils 2 and 2 are formed on both surfaces of a substrate 1, and an insulating film 3 is provided to cover each of the coils 2 and 2 and the substrate surface. The magnetic film 4 is covered, and the central portions of the coils 2 and 2 are electrically connected through a through hole 5 formed in the central portion of the substrate 1.
In addition, the terminals 6 are respectively connected to the coils 2 and 2 on both sides of the substrate 1.
Are exposed to the outside of the substrate 1. In the inductor B having this configuration, the planar coils 2 and 2 are sandwiched between the magnetic films 4 and 4 with the insulating film 3 interposed therebetween, whereby the inductors are configured between the terminals 6 and 6.

The substrate 1 is a substrate made of a ceramic material, a Si wafer substrate, a resin substrate, or the like.
When the substrate 1 is made of a ceramic material, alumina,
Zirconia, silicon carbide, silicon nitride, aluminum nitride,
Various types such as steatite, mullite, cordierite, forsterite, and spinel can be appropriately selected and used, but in order to make the coefficient of thermal expansion close to the coefficient of thermal expansion of Si, the thermal conductivity is large, and the bending strength is large. It is preferable to use aluminum nitride or the like having a large size.

The plane coil 2 is made of a highly conductive metal material such as copper, silver, gold, aluminum or an alloy thereof, and is electrically connected in series, vertically or in accordance with the inductance, the DC superposition characteristic, the size and the like. It can be arranged laterally with an insulating film interposed therebetween. Further, a transformer can be configured by providing a plurality of planar coils 2 in parallel. Further, the planar coil 2 can be formed into various shapes by photoetching after forming the conductive layer on the substrate. As a method for forming the conductive layer, an appropriate method such as press-compression bonding, plating, metal spraying, vacuum deposition, sputtering, ion plating, or screen printing firing method may be used.

The insulating film 3 is provided to prevent a short circuit due to conduction with the magnetic film 4 when the flat coil 2 is energized. The insulating film 3 is preferably made of a polymer film such as polyimide, or an inorganic film such as SiO ₂ , glass or hard carbon film. The insulating film 3 is formed by a method of firing after printing paste, a hot dipping method,
It is formed by a method such as thermal spraying, vapor phase plating, vacuum deposition, sputtering, or ion plating. Magnetic film 4
Is composed of the soft magnetic film of the soft magnetic alloy having the composition described above. Specifically, indicated by Fe _x M _y O _z T _w a composition formula, x indicating the composition ratio, y, z, w is 50 ≦ x ≦ with at%
75, 5 ≦ y ≦ 30, 15 ≦ z ≦ 25, 0 <w ≦ 5, 15
It is assumed that the relation ≦ z + w ≦ 30 is satisfied.

The inductance can be measured by applying a sinusoidal alternating current having a frequency of several hundred kHz and an amplitude of several mA to the inductor B constructed as described above, and a measured value of several hundred μH can be obtained. Further, the inductor B having the above-mentioned configuration is small, thin and lightweight, and has the magnetic film 4 having excellent magnetic characteristics, which contributes to the reduction in size and weight of the planar magnetic element and the excellent inductance. Show.

Next, FIG. 2 shows a second structural example of an inductor constituted by using a magnetic film of a soft magnetic alloy having the above composition.
In the inductor (thin magnetic element) C of this example, the oxide film 11, the magnetic film 12, and the insulating film 13 are sequentially stacked on the substrate 10, the planar coil 14 is formed on the insulating film 13, and the planar coil 14 is formed. An insulating film 15 is formed so as to cover the insulating film 13, and a magnetic film 16 is formed on the insulating film 15. The substrate 10 is made of the same material as the substrate 1 of the previous example, the magnetic film 12 is made of the same material as the magnetic film 4 of the previous example, and the insulating film 13 is made of the same material as the insulating film 3 of the previous example. Consists of. The oxide film 11 can be formed by heating a Si wafer to thermally oxidize it when a substrate such as a Si wafer is used as the substrate 10. However, the oxide film 11 is not essential and may be omitted. Similar to the inductor B of the above-described example, the inductor C of the configuration of this example also exhibits excellent inductance, is small and lightweight, and contributes to reduction in size and weight of the thin magnetic element.

[0019]

【Example】

(1) Film formation Using an RF magnetron sputtering device, a composite target in which various pellets of each element of M or T of the present invention are arranged on a Fe target is used, and Ar + 0.1 to 1.0%
Sputtering was performed in an O 2 atmosphere, and the sputtering time was adjusted so that the film thickness was about 2 μm. When B and C were added to the film to be obtained, a composite target in which B or C pellets were placed on the target was used.
When C is added, CO gas may be introduced into the sputtering atmosphere. The main sputtering conditions are shown below. Pre-evacuation: 1 × 10 ^-6 Torr or less High frequency power: 400 W Ar gas pressure: 6-8 × 10 ^-3 Torr Substrate: Crystallized glass substrate (indirect water cooling) Distance between electrodes: 72 mm

(2) Heat treatment After film formation, in order to improve the soft magnetism of the film, in a vacuum heating furnace,
Annealing treatment was carried out in which there is no magnetic field or in a magnetic field, and the temperature is kept in the temperature range of 300 to 600 ° C. for 60 to 360 minutes and gradually cooled. (3) Measurement The composition of the obtained alloy magnetic film was determined by an inert gas melting infrared absorption method. The saturation magnetic flux density (Bs) and coercive force (Hc) of the alloy magnetic film after the heat treatment (2) were measured by VSM. The specific resistance (ρ) was measured by a four-terminal method. The results are also shown in Tables 1 and 2 below.

[0021]

[Table 1]

[0022]

[Table 2]

Next, _{referring to} FIG. 3, Fe _90.4 Hf _9.3 O _19.7 C
A soft magnetic alloy film sample having a composition of _0.6 and Fe _68.9 Hf _10.2
The results of scanning analysis by X-ray analysis in the as-deposited state of a soft magnetic alloy film sample having a composition of O _19.9 B _1.0 are shown. From these results, it is understood that the peak of the (110) plane of bccFe and the halo pattern peculiar to the amorphous phase are included.

Next, in the alloy film represented by Fe _x Hf _y O _z B _w , the measurement results of the saturation magnetic flux density and the specific resistance before heat treatment of the alloys of each composition ratio are shown in FIG. In FIG. 4, among the values of the two steps attached to the bottom of each point (-) indicating the composition ratio, the value of the upper step is the saturation magnetization (Is: unit T (Tesla)) and the value of the lower step is Specific resistance (ρ: unit μ
Ωcm). The boundary between the specific resistance values shown by the chain line in FIGS. 4 and 5 is the specific resistance value of the FeHfO ternary alloy containing no B. From FIGS. 4 and 5 and the results of Tables 1 and 2, it can be seen that the smaller the Fe content, the higher the specific resistance. Therefore, in the present invention, the lower limit of the Fe content is set to 50 atomic% in order to increase the specific resistance and maintain the saturation magnetic flux density of at least 0.5T or more. In addition, FeHfO
In the system with B added, the Fe concentration (B
It was also found that a high specific resistance can be obtained even when (s is high).

Next, the magnetic permeability (μ _off ) was measured by changing the frequency of the external magnetic field. The sample used for the test is F
e A soft magnetic alloy film having a composition of _68.9 Hf _10.2 B _1.0 O _19.9 was used and heat treated at 400 ° C. for 6 hours in a rotating magnetic field. The measurement result is shown in FIG. In FIG. 6, μ ′
Indicates the real part of magnetic permeability, μ ″ indicates the imaginary part of magnetic permeability, and the saturation magnetization Is of this sample was 1.4T. From the results shown in FIG. 6, Fe _68.9 Hf _10.2 B _1.0 O _19.9 within the scope of the present invention is obtained.
It is clear that the soft magnetic alloy having the following composition maintains a high magnetic permeability even in a high frequency band, and it is understood that it is very excellent as a magnetic material for high frequency. Also,
The value of the real part and the value of the imaginary part of permeability become equal, that is, Q
The value of becomes 1 in a band slightly exceeding 200 MHz, and it is clear that the value of Q obtained as the value of (real part of permeability / imaginary part of permeability) can be maintained up to a high frequency band. .

Next, Fe ₇₆ Hf ₂₄ and Fe _54.9 Hf _11.0 O
FIG. 7 shows the X-ray optical spectroscopy analysis results for alloy samples of each composition of _34.1 and Fe _54.9 Hf _11.0 O _34.1 . The concentration of O in in FIG. () (%) Shows the flow ratio is the ratio of O ₂ occupying the sum of Ar ₂ and O _2. As can be seen from this figure, there is no peak corresponding to Fe-O for Fe, and the oxide of Fe does not precipitate even if O is added, whereas for Hf, as O is added, H
It hardly exists in f alone, but exists in the form of Hf-O. It is considered that this Hf-O is contained in a large amount in the amorphous material, and the resistance of the amorphous material is increased. This situation is F
The same applies to a multi-element system in which the elements M and T are added to the ternary system of eHfO. The crystal phase part contains a large amount of Fe, the element M and O are small, and the amorphous phase part contains a large number of elements M and O. Become. Therefore, even in the composition system of the present invention, a large amount of the element M is contained in the amorphous phase.
This is the cause of the high resistance, since it contains O and O. Further, since B and O have a property of easily bonding, it can be presumed that B is also contained in the amorphous material in a large amount.

[0027]

As described above, the soft magnetic alloy of the present invention is an Fe-based alloy having a specific composition and a specific composition ratio, and has achieved high saturation magnetic flux density, low coercive force, and high specific resistance. Since it is a soft magnetic alloy, it greatly contributes to reduction in size and weight and improvement in performance of magnetic elements such as thin film transformers, cores for magnetic heads, thin film inductors, and switching elements. Further, if the soft magnetic alloy according to the present invention is 3
Since a high specific resistance of 20 to 2 × 10 ⁵ can be obtained, when a soft magnetic alloy according to the present invention is used to form a magnetic element, it is possible to suppress eddy current loss in the high frequency region and to reduce eddy current loss. It is possible to provide a magnetic element with less power consumption.

In the soft magnetic alloy according to the present invention,
By including one or two of B and C in the range of 0.3 to 3.0 at%, it becomes possible to reliably obtain a particularly high specific resistance, and a small eddy current loss in the high frequency band. Can be surely obtained.

Further, a plane coil is formed on the substrate, the plane coil is covered with an insulating film, and a magnetic film of a soft magnetic alloy having the above composition is provided so as to cover the plane coil and the insulating film. The magnetic film of an excellent soft magnetic alloy having a low coercive force, a high saturation magnetic flux density, and a high specific resistance can be applied to the magnetic element, so that a small-sized, lightweight and high-performance planar magnetic element can be provided. You can Therefore,
It is possible to provide a compact and lightweight planar magnetic element.

[Brief description of drawings]

FIG. 1 (a) is a plan view showing a first example of a planar magnetic element according to the present invention, and FIG. 1 (b) is AA of FIG. 1 (a).
It is sectional drawing which follows a line.

FIG. 2 is a sectional view showing a second example of the planar magnetic element according to the present invention.

[Fig. 3] Scanning by X-ray analysis of the soft magnetic alloy film sample having a composition of Fe _90.4 Hf _9.3 O _19.7 C _{0.6 and} the soft magnetic alloy film having a composition of Fe _68.9 Hf _10.2 O _19.9 B _{1.0 as-formed.} It is a figure which shows the result of analysis.

FIG. 4 is a triangular composition diagram showing the relationship between the addition amount of each element and the saturation magnetization and the specific resistance in the Fe—Hf—O—B based alloy film according to the present invention.

FIG. 5 is a triangular composition diagram showing the relationship between the content of each element and the saturation magnetization and the specific resistance in the Fe—Hf—O—C based alloy film according to the present invention.

FIG. 6 is a diagram showing frequency dependence of a real part and an imaginary part of magnetic permeability in a soft magnetic alloy film having a composition of Fe _68.9 Hf _10.2 B _1.0 O _19.9 .

FIG. 7 Fe ₇₆ Hf ₂₄ and Fe _54.9 Hf _11.0 O _34.1 and Fe
_54.9 is a diagram showing an X-ray light spectral analysis of each composition sample Hf _11.0 O _34.1.

[Explanation of symbols]

 A, B Inductor (thin magnetic element) 1, 10 Substrate 2, 14 Planar coil 3, 13, 15 Insulating layer 4, 12, 16 Magnetic film

Claims (4)

[Claims] 1. A crystal phase mainly composed of Fe, having a body-centered cubic structure and having an average crystal grain size of 30 nm or less, and an amorphous phase surrounding the crystal phases, wherein the amorphous phase is Ti or Zr. , Hf, Nb, Ta, M
one or more elements M selected from o, W and rare earth elements, and one or two elements T of B and C
And O and an oxide of element M or element T as main components, and the specific resistance of this amorphous phase is higher than the specific resistance of the crystalline phase. . 2. The Fe-based soft magnetic alloy according to claim 1, wherein the Fe-based soft magnetic alloy is represented by the following composition formula. Fe _x M _y O _z T _w here, x indicating the composition ratio, y, z, w is at%, 50 ≦ x
≦ 75, 5 ≦ y ≦ 30, 15 ≦ z ≦ 25, 0 <w ≦ 6, 1
The relation of 5 ≦ z + w ≦ 30 is satisfied. 3. The w representing the composition ratio is 0.3 ≦ w ≦ 3.0.
3. The F according to claim 2, characterized in that
e-based soft magnetic alloy. 4. A spiral planar coil on a substrate,
An insulating film, magnetic film of soft magnetic alloy is laminated magnetic film of the soft magnetic alloy, is represented by a composition formula _{Fe x M y O z T w} , M is, Ti, Zr, H
f, Nb, Ta, Mo, W and one or more elements selected from rare earth elements, T represents one or two elements of B and C, and the composition ratio x, y, z, w Is at%,
50 ≦ x ≦ 75, 5 ≦ y ≦ 30, 15 ≦ z ≦ 25, 0 <w ≦
A thin magnetic element characterized by being a magnetic film satisfying the relationship of 5, 15 ≦ z + w ≦ 30.