JP3506364B2 - Magnetic thin film and magnetic head using 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 magnetic sensors such as recording heads, magnetic reproducing heads and magnetic impedance sensors of hard disk drives (HDD), magnetic sensors such as magnetic coils and inductors. The present invention relates to a magnetic thin film having a high saturation magnetic flux density used in circuit components and the like, and a magnetic head using such a magnetic thin film.

[0002]

2. Description of the Related Art In recent years, the maximum recording frequency of HDDs has been remarkably increased, and high-density recording media are becoming higher in coercive force. Therefore, the recording head material is required to be a magnetic material having a high saturation magnetic flux density, a high resistivity ρ, a proper uniaxial anisotropy even after being processed into a fine shape, and a high magnetic permeability μ in a high frequency band. There is.

[0003]

In order to meet these demands, the present inventors have established that M ₁ X ₁ A ₁ / M ₂ X ₂ A ₂ (M is a magnetic metal, X is a non-magnetic metal or semimetal, A has developed a multilayer film represented by O or N (Japanese Patent Application No. 10-249).
360). However, the M ₁ X ₁ A ₁ / M ₂ X ₂ A ₂ multilayer film has a low magnetic permeability in a high frequency band in a composition region in which the content of the element X ₁ in the magnetic layer and the content of the element X ₂ in the intermediate layer are small. There was a problem to be further improved.

The present invention solves the above problems and, in particular, X ₁
An object of the present invention is to provide a magnetic thin film having a high saturation magnetic flux density with improved magnetic permeability in a high frequency band even in a composition region containing a small amount of H, and a magnetic head using the magnetic thin film.

[0005]

In order to achieve the above object, the magnetic thin film of the present invention has a composition formula (M _a X _b ) _100-d A
_d (where M is at least one magnetic metal selected from Fe, Co and Ni, and X is Mg, Ca, Sr,
Ba, Si, Ge, Sn, Al and Ga, and F
e, at least one element selected from transition metals other than Co and Ni, A is at least one element selected from O and N, a, b and d are 2 ≦ b ≦ 8, a + b
= 100, a numerical value in the range of 0 ≦ d ≦ 10), and the thickness Dm per layer is 50 nm ≦ Dm ≦ 50.
A magnetic layer having a range of 0 nm, the M, the X, and an oxygen amount larger than that of the magnetic layer, and an intermediate layer having a thickness Dn per layer in the range of 2 nm ≦ Dn ≦ 10 nm. It is characterized in that they are alternately laminated.

In the present specification, the transition metal is
The group 3A element to the group 7A element, the group 8 element, the group 1B element, and the group 2B element are meant. Also, subscripts a, b, d
Further, c described later is a numerical value for indicating all atomic%.

As described above, the magnetic thin film of the present invention realizes a high saturation magnetic flux density by having a composition region containing a small amount of X (small b). On the other hand, direct coupling of the magnetic crystal grains between the magnetic layers, which tends to occur when b is reduced, is suppressed by using the magnetic layer and the intermediate layer having the thickness within the above range. As a result, it is considered that strong magnetostatic coupling was realized and high-frequency characteristics were improved.

In the magnetic thin film of the present invention, M is preferably Fe, FeCo alloy or FeCoNi alloy.

X and A contained in the magnetic layer have the effects of improving the corrosion resistance, refining the crystal grains of the magnetic metal, reducing the magnetocrystalline anisotropy of the magnetic crystal grains, and reducing the magnetostriction. Provide at least one of them. For example, when M is Fe, X, which depends on the amount of each added, Zn, Pt, Rh, Ru, etc. enhance corrosion resistance, and Cr, Ge, Ga, V, Al, Si, Ti, Mo The crystal magnetic anisotropy is reduced, and Ti, Si and Sn reduce the magnetostriction. Even if one kind of X is effective, even if two or more kinds of X are added in combination, the effect of further reducing the crystal grain size becomes remarkable. By further adding A, the crystal grain size can be made finer and the soft magnetic characteristics can be improved.

However, when X is added to the extent that b is larger than 8 or A is added to the extent that d is larger than 10, the saturation magnetic flux density (Bs) is remarkably lowered.

In the above magnetic thin film, when the thickness (Dm) of the magnetic layer is smaller than 50 nm, the Bs is remarkably reduced. On the other hand, if Dm is larger than 500 nm, sufficient magnetostatic coupling cannot be realized. If the magnetostatic coupling is not enough,
For example, in a state where the magnetic thin film is finely processed to have a minimum width of about several hundreds nm, good high frequency characteristics cannot be obtained. Also,
When the thickness (Dn) of the intermediate layer is smaller than 2 nm, the separation between the magnetic layers becomes insufficient and the soft magnetic characteristics deteriorate. On the other hand, when Dn is larger than 10 nm, the magnetostatic coupling between the magnetic layers is weakened and the decrease of Bs becomes remarkable.

In the magnetic thin film of the present invention, when the magnetic layer contains nitrogen (N), γ'- is contained in the magnetic layer.
When the amorphous or fine crystal of Fe ₄ N is contained, it becomes possible to improve the soft magnetic property itself of the magnetic thin film. This is because the Fe ₄ N amorphous or microcrystal formed in the magnetic layer suppresses the grain growth of the magnetic crystal grains during the film formation and the heat treatment, and reduces the apparent magnetocrystalline anisotropy of the entire magnetic layer. It is considered that this is because a so-called miniaturization effect is generated.

In the magnetic thin film of the present invention, the magnetic
The layer has a composition formula (M_a(Si_100-cX ’ _c)_b)_100-dO_d(However
X'is Ge, Sn, Al and Ga, and F
Less selected from transition metals excluding e, Co and Ni
Both are one element, b is 3 ≦ b ≦ 8, and c is 0 ≦ c ≦ 50.
The thickness per layer D
m is 50 nm ≦ Dm ≦ 150 nm It is preferably in the range of.

As described above, by setting the contents of Si and X ′ contained in the magnetic layer within the above range, the magnetic crystal grains are mainly formed due to Si partially dissolved in the magnetic crystal grains of the magnetic layer. It is possible to reduce the crystal magnetic anisotropy and to minimize the increase in magnetostriction. As a result, it is possible to realize a magnetic thin film having excellent magnetic permeability even in a high frequency band.

Further, in particular, Si, Ge, Al, and G whose oxide formation free energy is smaller than that of Fe, Co, and Ni.
The thermal stability of the intermediate layer is improved by containing a predetermined amount of an element such as a, Ti, V, or Cr (the above X excluding the 7A group element, the 8 group element, and the 1B group element) in the magnetic layer. This is because inside the magnetic layer, the above-mentioned elements in the magnetic layer trap oxygen elements, which are contained in the intermediate layer and diffuse from the thermally unstable oxide of the M element, into the magnetic layer in the vicinity of the intermediate layer. It is thought that this is to suppress the diffusion into It is also considered that the generated oxide also acts as a barrier layer that suppresses oxygen diffusion from the intermediate layer.

In this magnetic thin film, when b is less than 3, the effect of reducing the crystal magnetic anisotropy energy due to Si or the like cannot be sufficiently obtained, and the thermal stability is also insufficient. Further, when c is larger than 50, the above-mentioned effect of Si cannot be sufficiently obtained.

In the above magnetic thin film, M is preferably Fe. This is because it is easy to realize a relatively low magnetostriction together with a high saturation magnetic flux density. Such magnetic material is
When used in a DD recording head unit, it is possible to suppress recording noise caused by contact with a disk or the like.

In the above magnetic thin film, the magnetic layer contains columnar or needle-like magnetic crystal grains, and the average crystal width dw (average crystal grain size in a plane parallel to the substrate surface) of the magnetic crystal grains is , 5 nm ≦ dw ≦ 100 nm is preferable. This is because a higher saturation magnetic flux density and a higher magnetic permeability in the high frequency band can be realized. When dw is smaller than 5 nm, the grain boundaries of crystal grains increase and the Bs decreases significantly. On the other hand, when dw is set to be larger than 100 nm, for example, when the magnetic thin film is used after being finely processed to have a shortest width of several hundreds nm,
The size of the crystal grain size and the shortest width are similar. Therefore, the hard axis direction of the magnetic thin film is strongly influenced by the hard axis direction of the magnetic crystal grains, and it is difficult to form the hard axis direction in a direction preferable for the device.

In the above magnetic thin film, the intermediate layer preferably contains fine crystal grains having an average crystal grain size dg in the range of 1 nm ≦ dg <Dn. A part of such fine crystal grains may be included in the intermediate layer. When the size of the fine crystal grains is Dn or more, it becomes difficult to separate the magnetic layers, and the soft magnetic characteristics of the magnetic thin film deteriorate. The intermediate layer may be basically amorphous, but as described above, by adopting a form including microcrystals smaller than the width of the intermediate layer, a columnar or needle-like shape that grows with the microcrystals as nuclei is formed. Crystals are easily miniaturized, and a magnetic layer having the above preferable average crystal width can be formed.

In the above magnetic thin film, if the initial formation layer is from the intermediate layer side of the magnetic layer formed on the intermediate layer to 1/3 of the thickness of the magnetic layer, the initial formation layer is It is preferable to have a total oxygen and nitrogen content higher than the total oxygen and nitrogen content of the magnetic layer. In such a magnetic thin film, since the initially formed layer is made finer by oxygen and / or nitrogen, the crystal width of the magnetic crystal grains in the remaining magnetic layer that grows mainly using the initially formed layer as a nucleus is made finer as a whole. To be done. Therefore,
The soft magnetic characteristics of the magnetic thin film are improved, and Bs can be maintained higher than that of the film in which the entire magnetic layer contains a large amount of oxygen and nitrogen.

Further, in the above magnetic thin film, when the shortest film width per one magnetic layer is Dfw, it is preferable that Dm ≦ Dfw ≦ 30 μm. Here, the shortest film width means the length of the shortest portion of the magnetic layer in the in-plane direction of the film. With such a magnetic thin film, good characteristics in a high frequency band can be realized even if processed into a fine shape.

When Dfw is shorter than the film thickness Dm of one magnetic layer, the demagnetizing field tends to cause magnetization to tilt from the vicinity of the film surface to the direction perpendicular to the film surface, deteriorating the soft magnetic characteristics. Further, by setting Dfw to 30 μm or less as described above, the magnetization direction in the magnetic layer is easily oriented in the shortest film width direction, and as a result, the magnetization direction of the miniaturized magnetic thin film is controlled by the size. It is possible to suppress deterioration of high frequency characteristics due to ferromagnetic resonance.

In order to achieve the above object, the magnetic head of the present invention is characterized by including the above magnetic thin film.

[0024]

BEST MODE FOR CARRYING OUT THE INVENTION The magnetic thin film of the present invention is preferably formed in a low gas pressure atmosphere. Such a film forming method is not particularly limited, but for example, a radio frequency (RF) magnetron sputtering method, a direct current (D)
C) A sputtering method represented by a sputtering method, a facing target sputtering method, an ion beam sputtering method, and various vapor deposition methods can be mentioned.

For example, when the sputtering method is used,
First, the composition of the alloy target is determined in consideration of the compositions of the magnetic layer and the intermediate layer after film formation, and the alloy target is sputtered in an inert gas to form the magnetic layer and the intermediate layer on the substrate. A magnetic thin film can be manufactured by alternately forming the above. In this case, on the alloy target,
Sputtering may be performed by disposing the additive element pellets, or a reactive sputtering method in which a part of the additive element is introduced into the apparatus in a gas state may be applied. The number of electrodes for discharging may be one, depending on the composition.

When such a sputtering method is applied, the discharge gas pressure, the discharge power, the temperature of the substrate, the bias state of the substrate, the magnetic field value on and near the target, the shape of the target, and the target shape. By controlling the film formation conditions such as the direction of incident particles and the type of discharge gas, the structure of the magnetic thin film to be formed and the apparent thermal expansion coefficient,
It is possible to control the difference in film characteristics due to the positions of the substrate and the target. The magnetic thin film immediately after the film formation may be heat-treated at a predetermined temperature in a magnetic field or no magnetic field, if necessary. In this case, the heat treatment atmosphere is preferably vacuum or inert gas, and the heat treatment temperature is 100 to 35.
0 ° C is preferred.

The magnetic thin film as described above can be preferably used for magnetic devices such as magnetic sensors and magnetic circuit parts, but in particular, MIG (Metal In Gap) heads and LAM heads (Lamination Heads). And a magnetic head such as a hard disk head.

An example of such a magnetic head will be described below with reference to the drawings.

The MIG head shown in FIG. 1 is provided with the magnetic thin film 2 of the present invention near the magnetic gap 4 of the magnetic core 1 made of ferrite. The magnetic gap 4 is sandwiched by the glass 3 from both sides. Further, the hole 6 is formed to pass an electromagnetic coil (not shown).

The LAM head shown in FIG.
1 has a structure in which the magnetic thin film 16 of the present invention is sandwiched. The magnetic thin film 16 is used as a laminate with the insulating layer 17. This laminated body is formed so as to be orthogonal to the magnetic gap 12, and is arranged so that the laminated cross section faces the tape running surface 13. Similar to the magnetic head of FIG. 1, this magnetic head also has holes 14 for winding the electromagnetic coil.

The hard disk head shown in FIG.
A reproducing lower shield film 39, a reproducing lower gap film 38, and a GMR (Giant Magnetoresistance) film 3 are formed on a substrate 40.
3, a hard magnetic film 35, a reproducing upper gap film 34, a reproducing upper shield film / lower recording magnetic pole 36, and a recording gap film 32 are sequentially formed. Further, terminals 37 are interposed between the hard magnetic film 35 and the reproducing upper gap film 34 from both sides toward the GMR portion 33. Further, on the recording gap film 32, an upper recording magnetic pole 31 having a predetermined film thickness 42 and having a recording width 41 is formed.

With the magnetic head using the magnetic thin film of the present invention, excellent recording characteristics can be realized in the high frequency band, especially in magnetic recording of 50 MHz or more.

[0033]

EXAMPLES In the following examples, each thin film was formed by using the RF magnetron sputtering method or the DC magnetron sputtering method. The film structure was measured using X-ray diffraction (XRD), and the transmission electron microscope (TE
M) was used for observation. The composition analysis was evaluated by EPMA. The magnetic permeability was evaluated by 1-turn coil, and the saturation magnetic flux density was evaluated by VSM. The details of the examples will be described below.

Example 1 In this example, the magnetic layer is made of Fe.
Focusing on a magnetic thin film having (Si) N and Fe (Si) ON as the intermediate layer, the composition range, the magnetic layer thickness, the intermediate layer thickness, the fine structure, etc., in which the magnetic permeability at the high frequency is optimized were investigated. The components in parentheses are not included depending on the sample.

The film forming conditions are as follows. Substrate: Non-magnetic ceramic substrate Substrate temperature: 200 ° C. Target: Fe or FeSi alloy target Target film forming substrate: Rotating target Size: 3 inches Discharge gas pressure: 3 mTorr Discharge power: 300 W Sputtering gas: Magnetic layer Ar + N ₂ : Nitrogen flow rate ratio (N ₂ / (Ar + N ₂ )) 6
%: Intermediate layer Ar + O ₂ + N ₂ : Oxygen flow rate ratio (O ₂ / (Ar +
O ₂ )) 25%

The formation of the film is carried out by using the same Fe target or FeSi alloy target for the same magnetic thin film while the magnetic layer is in an Ar + N ₂ mixed gas atmosphere.
The intermediate layer was formed by further continuously introducing O ₂ gas into this atmosphere. In this way, the film thickness is 100n
m magnetic layers (Fe (Si) N) and 6 nm-thick intermediate layers (Fe (Si) ON) are alternately laminated by 10 layers,
A magnetic multilayer film having a thickness of about 1 μm was produced. In each of the magnetic multilayer films, the intermediate layer contained more oxygen than the magnetic layer. For comparison, a single-layer film made of a single magnetic layer having a thickness of 1 μm was prepared.

When the magnetic layer is represented by a composition formula of (Fe _a Si _b ) _100-d N _d (where a + b = 100, 0 ≦ d ≦ 10), the value of b and the single layer film and the multilayer film Table 1 shows the relationship with the initial magnetic permeability at 10 MHz.

[0038]   (Table 1)                   ――――――――――――――――――                                           Permeability                   Sample b (10MHz)                                       Single layer film Multilayer film                   ――――――――――――――――――                     aa 0 1500 500                     ab 1 1500 1000                     ac 2 1700 3000                     ad 3 2000 4000                     ae 5 2000 4000                     af 8 1500 3500                   ――――――――――――――――――

As shown in Table 1, in the multilayer films of sample ac to sample af in which b is 2 or more, high magnetic permeability was obtained. Further, in all the samples, the saturation magnetic flux density Bs was 1.7 T or more. The d, which represents the N content in the magnetic layer, was about 3 to 10 in all the samples.

The measured values shown in Table 1 are the values immediately after the film formation, but the basic tendency was the same as in Table 1 even after the manufactured sample was heat-treated at 300 ° C.

When the substrate temperature at the time of film formation was changed to room temperature, all samples had an initial magnetic permeability of 1 to 5.
It decreased by about 50%. As a result of examining the fine structure of the film by X-ray diffraction, diffraction lines of γ′-Fe ₄ N amorphous or microcrystalline were observed in all the magnetic films produced at a substrate temperature of 200 ° C. On the other hand, these diffraction lines were hardly observed from the film prepared at room temperature. Therefore, it is preferable that γ'-Fe ₄ N is present in the magnetic layer.

In the above magnetic thin film, it was confirmed that even if the value of b was more than 8, the improvement of the magnetic permeability due to the multilayer structure was obtained.
Decreased to about 1.6T.

[0043] Further, similar to the above, the magnetic thin film and a magnetic layer and a thickness of 6nm the intermediate layer is laminated with a thickness of 100 nm, result of various film deposition by changing the composition and the sputtering gas of the target, (M _a X _b ) _{100-d Ad} (M is at least one magnetic metal selected from Fe, Co and Ni, X is Mg, Ca, Sr, Ba, Si, Ge, Sn, Al and Ga and transitions other than M) At least one element selected from metals, A is at least one of O and N,
a, b, c are 2 ≦ b ≦ 8, a + b = 100, 0 ≦ d ≦ 1
It has been confirmed that excellent high frequency characteristics can be obtained by using a magnetic layer having a composition range of 0) and an intermediate layer containing M and X and containing more oxygen than the magnetic layer. .

Further, when the single-layer film and the multi-layer film produced so that d falls within the above range by changing the N ₂ flow rate ratio, the magnetic permeability of the multi-layer film is affected by the nitrogen content. It turned out to be difficult. As described above, since the multilayer film exhibits excellent magnetic permeability in a wide range of nitrogen content, it is expected that the yield will be improved during mass production, particularly when a magnetic thin film is formed in a relatively large area.

Next, the value of b was fixed at 2, the discharge gas pressure during film formation was changed within the range of 0.8 mTorr to 8 mTorr to prepare a multilayer film, and its magnetic permeability was investigated. Other film forming conditions are the same as above.

Each crystal size was examined by TEM observation of the cross section of the produced magnetic film. The magnetic layer of the formed multilayer film had columnar or needle-shaped magnetic crystal grains as a mother phase, and the height of the magnetic crystal grains was substantially equal to the thickness of the magnetic layer.

Table 2 shows the relationship between the crystal width of the magnetic crystal grains and the initial magnetic permeability at 10 MHz. Here, the crystal width dw of the magnetic crystal grains indicates the diameter of the column when the columnar crystal is assumed to be a cylinder, and the length of the minor axis of the ellipsoid when it is assumed to be a spheroid. Note that the TEM photograph that can be observed by the cross-sectional TEM was observed in parallel with the film surface by setting the crystal width dw to a value obtained by multiplying the measured length by 4 / π, since a columnar arbitrary cross-section is seen. In this case, the size of the crystal grain was corrected.

[0048]   (Table 2)                 ――――――――――――――――――                     Sample crystal width Permeability                                dw [nm] (10MHz)                 ――――――――――――――――――                       ba 4 300                       bb 5 1000                       bc 10 4000                       bd 20 3000                       be 100 2000                       bf 200 400                 ――――――――――――――――――

As shown in Table 2, when the magnetic layer contains columnar or acicular magnetic crystal grains, and the average crystal width dw of the magnetic crystal grains is in the range of 5 nm ≦ dw ≦ 100 nm, it is excellent. It was confirmed that high frequency characteristics were obtained.

Next, the value of b was fixed at 3, and the thickness of the magnetic layer and the thickness of the intermediate layer were variously changed, and the initial magnetic permeability of the multilayer film was investigated. Other film forming conditions are the same as above. The results are shown in Tables 3 and 4.

[0051]   (Table 3)               ――――――――――――――――――――――                 Sample Magnetic layer thickness Intermediate layer thickness Permeability                            Dm [nm] Dn [nm] (10MHz)               ――――――――――――――――――――――                   ca 30 6 3000                   cb 50 6 5000                   cc 100 6 4000                   cd 500 6 3000                   ce 600 6 2000               ――――――――――――――――――――――

As shown in Table 3, the thickness of the magnetic layer is 50.
Excellent high frequency characteristics could be obtained in the range of nm ≦ Dm ≦ 500 nm. On the other hand, the magnetic permeability of the sample ce was about the same as the magnetic permeability of the single-layer film shown in Table 1, and the saturation magnetic flux density was significantly reduced in the sample ca.

[0053]   (Table 4)               ――――――――――――――――――――――                 Sample Magnetic layer thickness Intermediate layer thickness Permeability                            Dm [nm] Dn [nm] (10MHz)               ――――――――――――――――――――――                   da 100 1 300                   db 100 2 2500                   dc 100 6 4000                   dd 100 10 3000                   de 100 15 1500               ――――――――――――――――――――――

As shown in Table 4, the thickness of the intermediate layer is 2n.
Excellent high frequency characteristics could be obtained in the range of m ≦ Dn ≦ 10 nm. On the other hand, in the sample da, as a result of TEM observation, it was confirmed that the magnetic crystal grains were not sufficiently separated. Further, in the sample de, the initial magnetic permeability is equal to or less than that of the single layer film, and the saturation magnetic flux density is significantly reduced.

From the above results, in order to obtain excellent saturation magnetic flux density and magnetic characteristics, 50 nm ≦ Dm ≦ 500 nm
Moreover, it was confirmed that it is preferable that 2 nm ≦ Dn ≦ 10 nm.

Example 2 In this example, the magnetic layer is made of Fe.
A composition range in which the magnetic permeability at high frequencies is optimal, centering on a magnetic thin film containing (Si) (O) and Fe (Si) O as the intermediate layer,
The magnetic layer thickness, the intermediate layer thickness, the fine structure, etc. were investigated. The components in parentheses are not included depending on the sample.

The film forming conditions are as follows. Substrate: Non-magnetic ceramic substrate Substrate temperature: room temperature Target: Fe target or FeSi alloy target During film formation Substrate: Fixed target Size: 3 inches Discharge gas pressure: 8 mTorr Discharge power: 300 W Sputtering gas: Magnetic layer Ar : Intermediate layer Ar + O ₂ : Oxygen flow rate ratio (O ₂ / (Ar + O ₂ )) =
25%

For forming the film, the same Fe target or FeSi alloy target was used for the same magnetic thin film, the magnetic layer was in an Ar gas atmosphere, and the intermediate layer was further continuously O _{2 in} this atmosphere. It was carried out by introducing gas. Thus, the magnetic layer (Fe (Si) (O)) having a film thickness of 100 nm and the intermediate film (Fe (Fe)) having a film thickness of 6 nm are formed.
(Si) O) and 10 layers are alternately laminated to obtain a film thickness of about 1
A μm magnetic multilayer film was prepared. In each of the magnetic multilayer films, the intermediate layer contained more oxygen than the magnetic layer.

When the magnetic layer is represented by a composition formula of (Fe _a Si _b ) _100-d O _d (where a + b = 100, 0 ≦ d ≦ 10), the value of b and the initial magnetic permeability at 10 MHz and 300 MHz. Table 5 shows the relationship with the saturation magnetic flux density.

[0060]   (Table 5)               ―――――――――――――――――――――                 Sample b Permeability Bs                               (10MHz) (300MHz) [T]               ―――――――――――――――――――――                   ea 0 150 150 2.03                   eb 2 200 200 1.98                   ec 3 500 400 1.95                   ed 5 1500 800 1.87                   ee 7 1900 1000 1.82                   ef 8 2300 1200 1.79               ―――――――――――――――――――――

As shown in Table 5, in samples ec to ef in which b was 3 or more, high magnetic permeability and high saturation magnetic flux density were obtained. It should be noted that d indicating the O content in the magnetic layer was about 0 to 3 on average in all the samples. It is considered that the O element may exist even though the O ₂ gas is not introduced during the production of the magnetic layer due to the residual oxygen during the production of the intermediate layer.

The measured values shown in Table 5 are the values immediately after the film formation, but the basic tendency was the same as in Table 5 even after the manufactured sample was heat-treated at 300 ° C. Also, when heat-treated, the magnetic permeability at 10 MHz is improved by 20 to 30%,
The magnetic permeability at 0 MHz was slightly reduced or was about the same.
Structural relaxation of the magnetic thin film contributes to the improvement of the magnetic permeability at 10 MHz, and the change of the magnetic permeability at 300 MHz is
It is considered that the decrease in the specific resistance of the film due to the heat treatment has an effect.

In the above magnetic thin film, it was confirmed that even if the value of b was more than 8, the improvement of the magnetic permeability due to the multilayer structure was obtained.
Fell to about 1.7T.

The cross-section TEM of the sample ef having a high magnetic permeability and the sample ea having a low magnetic permeability were observed and compared. As a result, in the sample ef, the magnetic layer has a crystal width of about 30-4.
It was found that the intermediate layer was composed of columnar crystals having a thickness of 0 nm, and the intermediate layer had a structure in which an amorphous phase slightly containing fine crystals of about 1 to 2 nm was used as a mother phase. Further, in the initial formation layer corresponding to a thickness of about 1/3 from the intermediate layer side where the magnetic layer was formed in the magnetic layer, the grain boundary was rich in oxygen. On the other hand, in the sample ea, the magnetic layer has a crystal width of about 60 to 70.
It was composed of columnar crystals having a size of nm, and grain growth that penetrated the intermediate layer was observed in part. Also, the grain size is 7n in this intermediate layer.
Part of the crystallites of m or more had grown.

From the comparison between sample ef and sample ea, it is considered that Si has the effect of suppressing unnecessary crystallization of the intermediate layer and separating the crystals of the magnetic layer. Further, it is considered that oxygen in the initial formation layer has an effect of suppressing grain growth in the width direction of magnetic crystal grains.

Next, the magnetic thin film whose substrate temperature at the time of film formation was room temperature (sample fa) or 200 ° C. (sample fb) was heat-treated in a uniaxial magnetic field of 300 [Oe] to obtain an initial magnetic permeability at 10 MHz. investigated. The amount of Si in the magnetic layer was set to 7%, which is the same as the sample ee. Also,
At the time of film formation of these samples, the influence of anisotropy due to a leakage magnetic field or the like is removed by rotating the substrate. Other film forming conditions are the same as above, like the samples shown in Table 5. The results are shown in Table 6.

[0067]   (Table 6)             ―――――――――――――――――――――――――                             Permeability according to heat treatment temperature (10MHz)             ―――――――――――――――――――――――――             Heat treatment temperature 200 ℃ 250 ℃ 300 ℃ 350 ℃             Sample fa 2000 3200 3800 1200             Sample fb 3800 4000 4000 3000             ―――――――――――――――――――――――――

As shown in Table 6, the substrate temperature was 200 ° C.
It can be seen that the sample fb formed as above exhibits high magnetic permeability at any heat treatment temperature. Cross-sectional TEM observation of each sample immediately after film formation revealed that the magnetic layers were all formed of columnar crystals, and the crystal width was about 30 to 40 nm. Also, especially the sample fb
In comparison with Sample fa, fine crystals of about 1 to 6 nm in which Fe is considered to be the mother composition were observed in the intermediate layer.
In the sample fb, the fact that the crystal width is as small as the film formation at room temperature despite the high substrate temperature is considered to be due to the random crystal growth with the fine crystals as nuclei. As described above, it is considered important that an appropriate crystalline substance exists in the intermediate layer.

Next, by arranging a predetermined amount of Si and Al chips on the Fe target, the composition formula (Fe _a (S
i _100-c Al _c ) _b ) _100-d O _d (provided that a + b = 100,
0 ≦ d ≦ 10) and a 100 nm-thick magnetic layer (FeSi (Al) (O)) and a 6 nm-thick intermediate layer (FeSi (Al) O) are laminated to form a multilayer film,
The relationship between the initial permeability at 10 MHz and the value of c was investigated. The value of b was fixed at 5. Other film forming conditions are as described above, like the samples in Table 5. The results are shown in Table 7.

[0070]   (Table 7)                 ―――――――――――――――――――                   Sample c c / (100-c) Permeability                                               (10MHz)                 ―――――――――――――――――――                     ga 0 0 1500                     gb 23.1 0.3 1600                     gc 33.3 0.5 1800                     gd 44.4 0.8 1500                     ge 50.0 1.0 1200                     gf 54.5 1.2 600                 ―――――――――――――――――――

As shown in Table 7, the value of c is 0≤c≤5.
A high magnetic permeability could be obtained in sample ga to sample ge of 0.

[0072] Further, similar to the above, the magnetic thin film and a magnetic layer and a thickness of 6nm the intermediate layer is laminated with a thickness of 100 nm, result of various film deposition by changing the composition and the sputtering gas of the target, (M _a ( Si _100-c X _c ) _b ) _100-d O _d (M
Is at least one magnetic metal selected from Fe, Co, and Ni, X is at least one element selected from Ge, Sn, Al, and Ga, and transition metals other than M, and a, b, and c are 3 ≦ b. ≦ 8, a + b = 100, 0 ≦ c
When a magnetic layer having a composition range of ≦ 50, 0 ≦ d ≦ 10) and an intermediate layer containing M and X and containing more oxygen than the magnetic layer are used, excellent high frequency characteristics are obtained. It was confirmed that it could be obtained.

Next, the same FeSi (O) / Fe as described above is used.
The value of b in the SiO multilayer film was changed from 5 to 7, and the thickness of the magnetic layer and the thickness of the intermediate layer were variously changed to prepare a magnetic multilayer film, and the initial magnetic permeability was investigated. Further, during film formation, the influence of anisotropy due to a leakage magnetic field or the like is removed by rotating the substrate. Other film forming conditions are the same as the above conditions, like the samples in Table 5. The results are shown in Tables 8 and 9.

[0074]   (Table 8)               ――――――――――――――――――――――                 Sample Magnetic layer thickness Intermediate layer thickness Permeability                            Dm [nm] Dn [nm] (10MHz)               ――――――――――――――――――――――                   ha 30 6 4000                   hb 50 6 5000                   hc 100 6 3200                   hd 150 6 1300                   he 200 6 500               ――――――――――――――――――――――

As shown in Table 8, the thickness of the magnetic layer is 50
Excellent high frequency characteristics could be obtained in the range of nm ≦ Dm ≦ 150 nm. The sample ha had a large magnetic permeability but a large decrease in the saturation magnetic flux density.

[0076]   (Table 9)               ――――――――――――――――――――――                 Sample Magnetic layer thickness Intermediate layer thickness Permeability                            Dm [nm] Dn [nm] (10MHz)               ――――――――――――――――――――――                   ia 100 1 400                   ib 100 2 1500                   ic 100 6 3200                   id 100 10 2000                   ie 100 15 1000               ――――――――――――――――――――――

As shown in Table 9, the thickness of the magnetic layer is 2n.
Excellent high frequency characteristics could be obtained in the range of m ≦ Dm ≦ 10 nm. In addition, in the sample ia, it was found from the TEM observation that the magnetic crystal grains were not sufficiently separated. Further, in the sample ie, the saturation magnetic flux density is remarkably reduced.

From the above results, in order to obtain excellent saturation magnetic flux density and magnetic characteristics, 50 nm ≦ Dm ≦ 150 nm
Moreover, it was confirmed that it is preferable that 2 nm ≦ Dn ≦ 10 nm.

Example 3 In this example, the high frequency characteristics of the magnetic thin film with respect to the shortest film width Dfw were investigated. The sample ee of Example 2 was used as the magnetic thin film. First,
The shortest film width of the magnetic thin film of this sample is 50 μm to 10 μm.
μm, and the sample was microfabricated into stripes by photolithography so that the hard axis direction was 10 mm in the longitudinal direction. Subsequently, heat treatment was performed at 250 ° C. in a uniaxial magnetic field of 300 [Oe] so that the film length direction was the easy axis of magnetization.

The initial magnetic permeability at 300 MHz in the longitudinal direction of the film width of each sample subjected to heat treatment after microfabrication and after heat treatment after microfabrication was examined. The results are shown in Table 10.

[0081]   (Table 10)               ――――――――――――――――――――――                 Sample shortest width Permeability Permeability                           After Dfw processing After heat treatment                           [μm] (300MHz) (300MHz)               ――――――――――――――――――――――                   ia 50 1500 700                   ib 30 1400 1100                   ic 20 1300 1000                   id 10 1200 1000               ――――――――――――――――――――――

As described above, the sample having the shortest width of 30 μm or less is high in spite of being subjected to the heat treatment in the direction orthogonal to the direction in which the magnetic permeability is originally improved so that the magnetic field applying direction becomes the easy axis of magnetization. It can be seen that the magnetic permeability is maintained. Considering this result together with the result of Table 6 in (Example 2), the thickness per magnetic layer is Dm and the shortest film width is Dm.
If fw is set, it is understood that a magnetic thin film satisfying Dm ≦ Dfw ≦ 30 μm can realize high frequency characteristics even if processed into a fine shape.

[0083]

As described above, according to the present invention,
It is possible to provide a magnetic thin film having excellent soft magnetic characteristics at high frequencies and having a high saturation magnetic flux density. This magnetic thin film
It can be provided by a low temperature process of 300 ° C or lower. In addition, there is a remarkable effect that the preferable hard axis direction is stable and excellent high frequency characteristics are exhibited even after processing into a fine shape.

Further, according to the present invention, by using the above magnetic thin film for a magnetic head, not only a magnetic recording head for high recording density which is excellent in mass productivity can be realized, but also a magnetic recording device can be made smaller and lighter. Moreover, low power consumption of the device can be achieved.

[Brief description of drawings]

FIG. 1 is a perspective view of a MIG type magnetic head which is one form of the magnetic head of the present invention.

FIG. 2 is a perspective view and a partially enlarged view of a LAM type magnetic head which is one form of the magnetic head of the present invention.

FIG. 3 is a partial cross-sectional view of a magnetic head for a hard disk, which is one form of the magnetic head of the present invention.

[Explanation of symbols]

1 magnetic core 2 Magnetic thin film 4 magnetic gap 11 Non-magnetic material 12 magnetic gap 16 Magnetic thin film 17 Insulation layer 31 upper recording magnetic pole 32 recording gap film 33 GMR film 34 Playback upper gap film 35 Hard magnetic film 36 reproducing upper shield film and lower recording magnetic pole 38 Reproduction lower gap film 39 Reproduction lower shield film

Continuation of the front page (56) References JP 62-35604 (JP, A) JP 10-223435 (JP, A) (58) Fields investigated (Int.Cl. ⁷ , DB name) H01F 10 / 12 G11B 5/127 G11B 5/31 H01F 10/30

Claims (9)

(57) [Claims] 1. A composition formula (M _a X _b ) _{100-d Ad} (where M is at least one magnetic metal selected from Fe, Co and Ni, and X is Mg, Ca, Sr, Ba, Si, G
e, Sn, Al and Ga, and at least one element selected from transition metals other than Fe, Co and Ni, A is at least one element selected from O and N, and a, b and d are 2 ≦. b ≦ 8, a + b = 100,
0 ≦ d ≦ 10), and the thickness Dm per layer is in the range of 50 nm ≦ Dm ≦ 500 nm, the magnetic layer, M, X, and more magnetic layers than the magnetic layer. A magnetic thin film comprising oxygen and an intermediate layer having a thickness Dn per layer in the range of 2 nm ≦ Dn ≦ 10 nm alternately laminated. 2. The magnetic layer contains nitrogen, and γ′-
The magnetic thin film according to claim 1, comprising Fe ₄ N amorphous or microcrystalline. 3. The magnetic layer has a composition formula (M _a (Si _100-c X ′
_c ) _b ) _100-d O _d (where X ′ is at least one element selected from Ge, Sn, Al and Ga, and transition metals other than Fe, Co and Ni, and b is 3 ≦ b ≦ 8, c
Is a numerical value in the range of 0 ≦ c ≦ 50), and the thickness Dm per layer is in the range of 50 nm ≦ Dm ≦ 150 nm. 4. The magnetic thin film according to claim 1, wherein M is Fe. 5. The magnetic layer contains columnar or needle-shaped magnetic crystal grains, and the average crystal width dw of the magnetic crystal grains is in the range of 5 nm ≦ dw ≦ 100 nm. Magnetic thin film. 6. The magnetic thin film according to claim 1, wherein the intermediate layer contains fine crystal grains having an average crystal grain size dg in the range of 1 nm ≦ dg <Dn. 7. The initial formation layer is defined as an initial formation layer which is from the intermediate layer side to 1/3 of the thickness of the magnetic layer in the magnetic layer formed on the intermediate layer. The magnetic thin film according to any one of claims 1 to 6, which has a higher total content of oxygen and nitrogen than the total content of. 8. The magnetic thin film according to claim 1, wherein the shortest film width Dfw per one magnetic layer is in the range of Dm ≦ Dfw ≦ 30 μm. 9. A magnetic head comprising the magnetic thin film according to claim 1. Description: