JP2950921B2 - Soft magnetic thin film - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a soft magnetic thin film, particularly to a soft magnetic thin film used for a magnetic head, a thin film inductor, and the like suitable for high-density recording.

<Related Art> Various soft magnetic materials such as Sendust and Permalloy are known as materials for soft magnetic thin films such as magnetic heads and thin film inductors.

In this case, for example, in the field of magnetic recording, a magnetic recording medium having a high coercive force Hc is used as the density of magnetic recording increases. In this case, in order to perform good recording on a magnetic recording medium having a high coercive force, it is necessary to generate a high-density magnetic flux from a magnetic head.

Therefore, a soft magnetic thin film having a high saturation magnetic flux density Bs is required for a magnetic head.

In addition, the magnetic permeability μ of the soft magnetic thin film is preferably high from the viewpoint of obtaining high recording / reproducing sensitivity.

Further, it is preferable that the electric resistivity ρ is high in terms of the high frequency characteristics of the magnetic permeability μ.

However, in Sendust and Permalloy, the saturation magnetic flux density
Since Bs is insufficient, sufficient writing cannot be performed on a high-coercivity magnetic recording medium having a coercive force Hc of 1400 Oe or more.

In addition, a multilayer film having a high saturation magnetic flux density and a high magnetic permeability in which several kinds of soft magnetic thin films are alternately stacked is known, but because of many manufacturing steps, it is complicated, and the production yield is low.
It has not been put to practical use yet.

<Problem to be Solved by the Invention> An object of the present invention is to provide a soft magnetic thin film having a high saturation magnetic flux density Bs, a high magnetic permeability μ, and a high electric resistivity ρ.

<Means for Solving the Problems> Such an object is achieved by the present invention of the following (1) to (3).

(1) Co, M (M is at least one element selected from Group 3A, Group 4A and Group 5A elements) and O, the content of M is 2 to 15 at%, and the content of O A soft magnetic thin film having an amount of 4 to 35 at%, having a main magnetic phase containing Co as a main component, and having at least 50% by volume of crystal grains of the main magnetic phase.

(2) The average crystal grain diameter D of the crystal grains of the main magnetic phase is 1000
<4> The soft magnetic thin film according to (1) above,

(3) The soft magnetic thin film according to (1) or (2), wherein the electric resistivity ρ is 150 × 10 ⁻⁶ Ω · cm or more.

<Function> The soft magnetic thin film of the present invention has a high saturation magnetic flux density Bs, a high magnetic permeability μ, and a high electric resistivity ρ.

For this reason, when the soft magnetic thin film of the present invention is applied to, for example, a magnetic head, it is possible to sufficiently write on a magnetic recording medium having a high coercive force, obtain high recording / reproducing sensitivity, and improve high frequency characteristics. I do.

<Specific Configuration of the Invention> Hereinafter, a specific configuration of the present invention will be described in detail.

The soft magnetic thin film of the present invention has an atomic ratio composition represented by the following formula.

Formula Co _{100- (a + b)} M _{a Ob In the} above formula, M is at least one selected from Group 3A, Group 4A, and Group 5A elements.

Of these, one of Y, La, Ce, Ti, Zr, Ta, Nb and Hf
More than species are preferred.

More preferably, denseness, adhesion strength and stability are high, and the film quality is good, such as small internal stress,
One or more selected from Y, Ta, Hf and Zr, particularly preferably, among them, Yc is low in that Hc is low, μ is high, magnetic properties are good, ρ is high, and high-frequency properties are good. preferable.

A is 2 to 15, preferably 3 to 13, particularly preferably 4 to 11.

Below the range, the coercive force Hc is high and the magnetic permeability μ is sufficient.
Can not be obtained.

If it exceeds the above range, the saturation magnetic flux density Bs decreases to 11 kG or less.

B is 4 to 35, preferably 7 to 28, particularly preferably 9 to 21.

Below the above range, the coercive force Hc is high and sufficient soft magnetic properties cannot be obtained.

If it exceeds the above range, the saturation magnetic flux density Bs decreases to 11 kG or less, and the coercive force Hc also increases, so that sufficient soft magnetic characteristics cannot be obtained.

In some cases, carbon and / or nitrogen may further be contained by replacing the oxygen portion.

In this case, the content of oxygen is preferably at least 50 at%, more preferably at least 80 at%, and particularly preferably 90 to 100 at%, based on the total of oxygen, nitrogen and carbon.

Thereby, particularly, ρ is improved, and the high frequency characteristics are improved.

Furthermore, part of Co can be replaced with one or more elements of Ni, Fe, and Mn.

The composition of the soft magnetic thin film of the present invention is, for example, El
It may be performed by the ectron Probe Micro Analysis (EPMA) method.

The thickness of the soft magnetic thin film may be appropriately selected depending on the application and the like, but is usually about 0.3 to 5 μm.

Such a soft magnetic thin film of the present invention usually has a main magnetic phase mainly containing Co and an oxide phase mainly containing an oxide of X. However, since the particles of the oxide phase are fine, detection by ordinary X-ray diffraction or the like is difficult.

The main magnetic phase is usually composed of crystal grains containing Co as a main component. The crystal particles may be composed of Co alone, or may be a solid solution of M or oxygen in Co.

The oxide phase is usually composed of M oxide, but may further contain M nitride, M carbide and the like. In this case, the oxide of M is usually present in the most stable oxide form, but may deviate slightly from the stoichiometric composition.

The average crystal grain size D of the crystal grains of the main magnetic phase is preferably 1000 ° or less.

If the ratio exceeds the above range, it is considered that the anisotropic dispersion cannot be reduced, and as a result, the coercive force Hc increases and soft magnetic characteristics cannot be obtained.

The average crystal grain size D is more preferably 300 ° or less, particularly preferably 20 to 300 °.

 In the case of the above range, a particularly high magnetic permeability μ is obtained.

When the average crystal grain size D is 1000 ° or less, particularly 300 ° or less, high corrosion resistance is obtained. Further, particularly when Y is contained as M, higher corrosion resistance can be obtained.

The average crystal grain diameter D of the crystal grains, the Co (111) half-value width W ₅₀ of the peaks of the X-ray diffraction line according to powder method measures may be obtained from the equation Scherrer below.

Formula D = 0.9λ / W ₅₀ cos θ In the above formula, λ is the wavelength of the X-ray used, and θ is the diffraction angle.

Further, it is preferable that the crystal grains of the main magnetic phase be present in an amount of 50% by volume or more, particularly 80% by volume or more.

Below this range, the coercive force Hc is large, soft magnetic properties cannot be obtained, and the saturation magnetic flux density Bs is low.

The volume ratio of the main magnetic phase composed of microcrystals may be determined by the volume ratio of the amorphous phase of the matrix and the precipitated microcrystalline phase using, for example, a transmission electron microscope.

To form the soft magnetic thin film of the present invention, a vapor phase method such as vapor deposition, sputtering, ion plating, and CVD may be used.

During film formation, the substrate is usually water-cooled. When the substrate temperature is high, the crystal grains of the main magnetic phase and the oxide phase of the soft magnetic thin film to be formed grow, so that the substrate temperature is preferably 200 ° C. or lower.

There is no particular limitation on the method of cooling the substrate, and for example, the film may be formed by water cooling.

To form a soft magnetic thin film by a sputtering method, for example, the following is performed.

As the target, an alloy cast, a sintered body, a composite target, or the like is used.

In order to mix oxygen into the film, reactive sputtering in an oxygen atmosphere may be used, or an oxide may be used as a target.

The sputtering is performed under an inert gas atmosphere such as Ar.

In the case of reactive sputtering, oxygen may be contained at about 0.2 to 2.5% by volume.

There is no particular limitation on the method of sputtering, and there is no particular limitation on the sputtering apparatus to be used, and an ordinary apparatus may be used.

The operating pressure is usually 3 to 3 in the case of RF sputtering.
Approximately 30 × 10 ^-3 Torr, 1.
The pressure may be about 5 to 2.5 × 10 ⁻⁴ Torr, and other conditions are appropriately determined according to the type of the sputtering method.

The film immediately after film formation may be amorphous or crystalline, that is, crystalline particles may be present.

Since M and oxygen have a strong affinity, the film undergoes a self-heat treatment by the heat of formation of the M oxide during film formation, so that good soft magnetic characteristics can be obtained.

Heat treatment is preferably performed to further improve the soft magnetic lag of the soft magnetic thin film. In this case, the following conditions are particularly preferable.

Heating rate: about 2 to 10 ° C / min Holding temperature: about 200 to 650 ° C, especially about 300 to 500 ° C Holding time: about 5 to 100 minutes Cooling rate: about 2 to 20 ° C / min Atmosphere: 1 × 10 ^-4 In a vacuum of Torr or less or in an inert gas such as Ar In the present invention, since the finely dispersed M oxide suppresses the crystal growth of the crystal particles due to the heat treatment, the average crystal particle diameter D is in the above range. Inside.

Coercive force Hc of the obtained soft magnetic thin film at DC to about 50 Hz
Is preferably 40e or less, more preferably 30e or less.

In addition, the initial magnetic permeability μi at 5 MHz is 600 or more, particularly 700 or more.

If the coercive force Hc exceeds the above range, or the initial permeability μ
If i is less than the above range, the recording / reproducing sensitivity tends to decrease when applied to a magnetic head.

The soft magnetic thin film has a saturation magnetic flux density Bs of 11 kG or more, particularly 13 kG or more.

If it is less than the above range, the overwrite characteristics deteriorate,
In particular, recording on a magnetic recording medium having a high coercive force becomes difficult.

The electrical resistivity ρ of the soft magnetic film is 150 × 10 ⁻⁶ Ωcm
As described above, in particular, those having a density of 180 × 10 ⁻⁶ Ω · cm or more can be obtained.

Therefore, the soft magnetic thin film of the present invention has a thickness of 2 μm, for example.
In the case of a thin film having a μi of about 2000, μi does not decrease up to a frequency of about 13 MHz, and a high magnetic permeability can be obtained even at a high frequency.

Note that Bs, Hc, μi, and ρ may be measured as follows.

Bs: Performed in a magnetic field of 10 kOe using a sample vibration magnetometer (VSM).

Hc: Performed using a thin-film histroscope.

μi: Determined by measuring the inductance at a measurement frequency of 5 MHz in a magnetic field of 3 mOe using an impedance analyzer.

ρ: Determined by measuring sheet resistance by the four-terminal method.

The soft magnetic thin film of the present invention can be applied to various magnetic heads such as a thin film magnetic head.

FIG. 1 shows a flying type thin film magnetic head according to a preferred embodiment of the present invention.

The thin-film magnetic head shown in FIG. 1 has an insulating layer 81, a lower pole layer 91, a gap layer 10,
3, coil layer 11, insulating layer 85, upper pole layer 95 and protective layer 1
It has 2 sequentially.

In the present invention, the slider 7 may be made of various known materials, and is made of, for example, ceramics or ferrite.

In this case, ceramics, particularly ceramics mainly containing A ₂ O ₃ —TiC, ceramics mainly containing ZrO ₂ , ceramics mainly containing SiC, or ceramics mainly containing AN are suitable. In addition, these may contain Mg, Y, ZrO ₂ , TiO _{2, and the} like as additives.

Various conditions such as the shape and size of the slider 7 may be any known conditions, and are appropriately selected according to the application.

 An insulating layer 81 is formed on the slider 7.

As the material of the insulating layer 81, any of conventionally known materials can be used. For example, when a thin film is formed by a sputtering method, SiO ₂ , glass, A ₂ O ₃ or the like can be used.

The thickness and pattern of the insulating layer 81 may be any known ones, for example, the thickness is about 5 to 40 μm.

The magnetic poles are usually provided as a lower magnetic pole layer 91 and an upper magnetic pole layer 95 as shown.

In the present invention, a soft magnetic thin film having the atomic ratio composition represented by the above formula is used for the lower magnetic pole layer 91 and the upper magnetic pole layer 95.

Therefore, a magnetic head having excellent overwrite characteristics even with a magnetic recording medium having a high coercive force and high recording / reproduction sensitivity, particularly, high recording / reproduction sensitivity at a high frequency can be obtained.

The pattern and thickness of the lower and upper magnetic pole layers 91 and 95 may be any known ones. For example, the lower magnetic pole layer 91
Is about 1 to 5 μm, and the thickness of the upper magnetic pole layer 95 is 1 to 5 μm.
It may be about μm.

Gap layer between lower pole layer 91 and upper pole layer 95
10 is formed.

For the gap layer 10, various known materials such as A ₂ O ₃ and SiO ₂ may be used.

Further, the pattern, thickness, and the like of the gap layer 10 may be any known one. For example, the thickness of the gap 10 is 0.
The thickness may be about 2 to 1.0 μm.

The material of the coil layer 11 is not particularly limited, and a commonly used metal such as A or Cu may be used.

There is no limitation on the winding pattern or the winding density of the coil, and a known coil may be appropriately selected and used. For example, the winding pattern may be any of a spiral type, a lamination type, a zigzag type, and the like.

The coil layer 11 may be formed by various vapor deposition methods such as a sputtering method and a plating method.

In the illustrated example, the coil layer 11 is spirally disposed between the upper and lower pole layers 91 and 95 as a so-called spiral type, and the coil layer 11 and the upper and lower pole layers 91 and 95 are spirally arranged.
Insulating layers 83 and 85 are provided between them.

As the material for the insulating layers 83 and 85, any of conventionally known materials can be used. For example, when a thin film is formed by a sputtering method, SiO ₂ , glass, A ₂ O ₃ or the like can be used.

On the upper pole layer 95, a protective layer 12 is provided. As the material of the protective layer 12, any conventionally known material can be used, and for example, A ₂ O ₃ or the like can be used.

In this case, any of conventionally known patterns and film thicknesses of the protective layer 12 can be used, for example, the film thickness is 10 to 50 μm.
m.

In the present invention, various resin coat layers may be further laminated.

The manufacturing process of such a thin film magnetic head is usually performed by forming a thin film and forming a pattern.

For the production of various thin films, as described above, a conventionally known vapor deposition method, for example, a vacuum deposition method, a sputtering method,
Alternatively, a plating method or the like may be used.

The pattern formation of each layer of the thin-film magnetic head can be performed by a conventionally known technique such as selective etching or selective deposition. The etching can be performed by wet etching or dry etching.

The thin-film magnetic head to which the present invention is applied is used in combination with a conventionally known assembly such as an arm.

In addition, various types of overwrite recording can be performed using the above-described thin film magnetic head.

The soft magnetic thin film of the present invention can be applied to various magnetic heads such as a MIG (metal-in-gap) head in addition to such a thin-film magnetic head.

Further, since sufficient magnetic properties can be obtained at a relatively low heat treatment temperature of about 300 ° C., the film can be formed on a polymer film such as polyimide, and thus can be applied to a thin film inductor and the like.

<Examples> Hereinafter, the present invention will be described in more detail with reference to specific examples of the present invention.

Example 1 A Co-YO soft magnetic thin film having an atomic ratio composition shown in Table 1 and a film thickness of about 1 μm was formed on a substrate using an RF sputtering apparatus.

First, a Y chip was placed on a pure Co (cobalt) target with good symmetry, a substrate was placed at a position 55 mm from the decoding target, and sputtering was performed with a mixed gas of Ar and O ₂ .

The substrate was made of crystallized glass (Photo Serum manufactured by Corning Incorporated) and was indirectly water-cooled to keep the temperature of the substrate at 100 ° C. or lower.

 The main film forming conditions are as follows.

Sputtering gas: Ar + 0.1% by volume O _{2 to} Ar + 2.5% by volume O ₂ Sputtering gas pressure: 5 × 10 ^-3 Torr Input power: 2.4 W / cm ² Deposition rate: 160Å / min Ultimate vacuum: 1 × 10 ^-6 Torr Next, in order to improve the magnetic properties, the degree of vacuum is 1 × 10 ^-6
After heat treatment at rr, a temperature of 500 ° C. and a holding time of 1 hour, various properties were evaluated by the following methods.

(1) Film composition The film composition was determined by EPMA using a film formed on an aluminum substrate having a purity of 99.85%.

(2) Initial magnetic permeability (μi) The magnetic permeability was determined by applying a ferrite yoke to the film surface, and measuring the inductance at a magnetic field of 3 mOe and a measurement frequency of 5 MHz using an impedance analyzer.

(3) Coercive force (Hc) The coercive force was determined using a thin-film histroscope.

(4) Saturation magnetic flux density (Bs) Measured in a magnetic field of 10 kOe using VSM.

(5) Electric resistivity (ρ) It was determined by measuring sheet resistance by a four-terminal method.

(6) Average crystal grain size of crystal grains (D) It was determined from the half width of the Co (111) peak using X-ray diffraction.

(7) Content of Crystal Particles The content was determined from the deposition ratio between the amorphous phase of the matrix and the precipitated microcrystalline phase using a transmission electron microscope.

For comparison, a 1 μm-thick Fe—Si—A film was formed in the same manner as described above, except that sputtering was performed in Ar using an alloy target having a composition of Fe ₇₄ Si ₁₈ A ₈ (at%).
A soft magnetic thin film was formed on a glass substrate.

Then, after performing a heat treatment at a degree of vacuum of 1 × 10 ⁻⁶ Torr, a temperature of 600 ° C. and a holding time of 1 hour, various characteristics were evaluated in the same manner as described above.

 The results are as shown in Table 1.

From the results shown in Table 1, the effect of the present invention is clear.

When μi was measured at a frequency of 1 to 20 MHz,
In Sample Nos. 1 and 2, a constant μi was obtained at 1 to 10 MHz, respectively, and the decrease in μi was slight even at 20 MHz.

 In addition, the corrosion resistance was also good.

Example 2 A Co—Ta—O soft magnetic thin film was produced as follows using an ion beam sputtering apparatus.

First, Ar ions are accelerated by the ion beam sputtering device with a bucket type ion gun with a diameter of 100 mm on the composite target in which Ta chips are placed on the Co target with good symmetry, and the target is placed at a predetermined distance from the target. A film having a thickness of about 1 μm was formed on the substrate.

In this case, a small amount of oxygen was flowed from a place near the substrate in the vacuum chamber, and reactive sputtering was performed.

Further, similarly to Example 1, crystallized glass was used for the substrate, and the substrate was indirectly water-cooled.

 The main film forming conditions are as follows.

Acceleration voltage: 1200V Beam current: 130mA Deposition rate: 160Å / min Ultimate vacuum: 1 × 10 ^-7 Torr Vacuum during deposition: 1.5 to 2.5 × 10 ^-4 Torr Next, improve the magnetic properties of the thin film obtained After performing a heat treatment at a degree of vacuum of 1 × 10 ⁻⁶ Torr, a temperature of 500 ° C. and a holding time of 1 hour, various characteristics were evaluated in the same manner as in Example 1.

 The results are as shown in Table 2.

From the results shown in Table 2, the effect of the present invention is clear.

In addition, a Co-MO soft magnetic thin film was formed using various metals selected from Group 3A elements, Group 4A elements and Group 5A elements, and the same evaluation was performed. was gotten.

Further, applying the soft magnetic thin film of the present invention to a magnetic head,
A thin film magnetic head was manufactured.

When recording and reproduction were performed on a magnetic recording medium having a high coercive force, excellent electromagnetic characteristics such as sufficient overwrite characteristics and high recording and reproduction sensitivity at high frequencies were obtained.

<Effect of the Invention> The soft magnetic thin film of the present invention has soft magnetic characteristics with high saturation magnetic flux density Bs, high magnetic permeability μ, low coercive force Hc, and high electric resistivity ρ.

 In addition, it has good corrosion resistance.

Further, since the above-mentioned characteristics can be obtained with a single-layer film, film formation is easy, and production yield and mass productivity are high.

When the soft magnetic thin film of the present invention is applied to, for example, a magnetic head, sufficient recording can be performed on a magnetic recording medium having a high coercive force, and sufficient overwrite characteristics can be obtained.

In addition, the recording / reproducing sensitivity, especially the recording / reproducing sensitivity at a high frequency, is significantly improved as compared with the conventional one.

[Brief description of the drawings]

FIG. 1 is a partial sectional view showing an example of a thin-film magnetic head to which the soft magnetic thin film of the present invention is applied. Reference numeral 7: slider 81, 83, 85 insulating layer 91 lower magnetic pole layer 95 upper magnetic pole layer 10 gap layer 11 coil layer 12 protective layer

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁶ , DB name) H01F 10/16

Claims (3)

(57) [Claims] 1. Co, M (M is a Group 3A element, a Group 4A element and a 5A
And at least one element selected from group III elements) and O, the content of M is 2 × 15 at%, and the content of O is 4 to
A soft magnetic thin film comprising 35 at%, having a main magnetic phase containing Co as a main component, and having crystal grains of the main magnetic phase present in 50% by volume or more of the whole. 2. An average crystal grain size D of crystal grains of said main magnetic phase.
2. The soft magnetic thin film according to claim 1, wherein 3. The soft magnetic thin film according to claim 1, wherein the electric resistivity ρ is 150 × 10 ⁻⁶ Ω · cm or more.