JPH05275233A - Soft magnetic film - Google Patents

Abstract

PURPOSE:To provide a soft magnetic film high in saturated magnetic flux density and excellent in soft magnetic property and favorable in heat resistance. CONSTITUTION:This is a soft magnetic film consisting of alloy, the composition of which is expressed substantially by some one general formula among T100-aBia, T100-a-bBiaOb, T100-a-b-c-dBiaMcXdOb, and T100-a-b-c-d-eBiaMcObXdNe (among the formulae, T shows at least one kind of element selected from Fe, Co, and Ni, and M at least one kind of element selected from Ti, Zr, Hf, Nb, Ta, W, Mo, Mn, and Cr, and X at least one kind of element selected from Al, Ga, In, C, Si, Ge, B, Sb, Pb, Zn, Au and a platinum element, and a, b, c, d, and e the numbers which satisfy 1<=a<=20, 0.01<=b<=10, 0.1<=c<=10, 0<=d<=5, 0.01<=e<=(at%), respectively).

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a soft magnetic thin film used for thin film magnetic head cores, flat inductors and the like.

[0002]

2. Description of the Related Art In recent years, for example, for magnetic disk devices and VTs.
The magnetic head for R is required to have a narrower track in order to improve the recording density. As a magnetic head satisfying such a demand, a so-called thin film magnetic head using a magnetic thin film formed by a thin film forming technique such as a sputtering method is used.

As the soft magnetic thin film used in the thin film magnetic head as described above, conventionally, thin films such as ferrite, Sendust alloy having Fe-Al-Si as a basic composition, and Co-based amorphous alloy are generally used. Came.

On the other hand, high density recording is being promoted also from the magnetic recording medium side, and for example, in order to realize high density recording, high coercive force is being increased. In order to sufficiently cope with such a high coercive force on the recording medium side with a thin film magnetic head, a soft magnetic thin film having a high saturation magnetic flux density is required. Further, in consideration of reproduction efficiency, it is necessary to have a high magnetic permeability, and a soft magnetic thin film having these magnetic characteristics is also required.

However, the conventional soft magnetic thin film as described above has a problem that the above-mentioned required characteristics cannot be satisfied. That is, ferrite has a low saturation magnetic flux density and is not suitable for high-density recording by increasing the coercive force of the magnetic recording medium. Moreover, although the saturation magnetic flux density of the sendust-based alloy is higher than that of ferrite, it is approximately 10 kG, so it cannot be said that it is sufficiently compatible with high-density recording. In the case of a Co-based amorphous alloy, the crystallization temperature is relatively low, so heat resistance (thermal stability) in the manufacturing process of the magnetic head becomes a problem, and the high magnetic permeability peculiar to the amorphous alloy cannot be obtained. There is a problem with the electromagnetic conversion characteristics.

[0006]

As described above, ferrite, sendust-based alloys, Co-based amorphous alloys, etc., which have hitherto been generally used as constituent materials of thin-film magnetic heads, have a low saturation magnetic flux density and a high heat resistance. Since the magnetic recording medium has a poor property and has a large deterioration of characteristics in the manufacturing process, there is a problem that it is not possible to sufficiently cope with the high coercive force on the magnetic recording medium side.

The present invention has been made in order to solve such a problem, and an object thereof is to provide a soft magnetic thin film having a high saturation magnetic flux density, excellent soft magnetic characteristics, and good heat resistance. There is.

[0008]

The first soft magnetic thin film in [the working means to an aspect of the present invention have the general _{formula: T 100-a Bi a .........} (1) ( wherein, T is selected from Fe, Co and Ni At least 1
Seed element, a is a number satisfying 1 ≦ a ≦ 20 (at%). The same applies hereinafter), and the composition is essentially composed of an alloy.

Further, the second soft magnetic thin film of the general _{formula: T 100-ab Bi a O} b ......... (2) ( wherein, b is a number satisfying 0.01 ≦ b ≦ 10 (at% ) Show.
The same applies hereinafter), and the composition is essentially composed of an alloy.

Furthermore, the third soft magnetic thin film of the general _{formula: T 100-abcd Bi a M} c X d O b ......... (3) ( wherein, M is Ti, Zr, Hf, Nb, Ta, W, Mo, Mn and Cr
At least one element selected from X, Al, Ga, I
n, C, Si, Ge, B, Sb, Pb, Zn, Au and at least one element selected from platinum group elements, and c and d are 0.
Numbers satisfying 01 ≤ c ≤ 10 and 0 ≤ d ≤ 5 (at%) are shown. The same applies hereinafter), and the composition is essentially composed of an alloy.

[0011] Further, a fourth soft magnetic thin film of the general _{formula: T 100-abcde Bi a M} c O b X d N e ......... (4) ( wherein, e is 0.01 ≦ e ≦ 10 (at %) Indicates the number that satisfies
It is characterized by being composed of an alloy whose composition is substantially represented by.

The Bi element in the above equations (1) to (4) hardly forms a solid solution with the T element (Fe, Co, Ni) and precipitates as fine particles. Therefore, it is crystallized by heat treatment from an amorphous state. At this time, it has an effect of preventing the crystal grains from coarsening and allowing fine crystal grains to appear. In addition, Bi also has the effect of refining the crystal grains when crystallizing during film formation. However, if the Bi content is less than 1 at%, the above-described grain refining effect cannot be sufficiently obtained, and if it exceeds 20 at%, the saturation magnetic flux density decreases. Bi
The more preferable content is 2 at% to 18 at%, and more preferably 4 at% to 15 at%.

As described above, by refining the crystal structure of the T element, a high saturation magnetic flux density can be realized and excellent soft magnetic characteristics can be obtained. Here, the average crystal grain size of the soft magnetic thin film is 100 nm or less. If the average crystal grain size exceeds 100 nm, the above effects cannot be sufficiently obtained. A more preferable value of the average crystal grain size is 60 nm or less, and further preferably 40 nm or less. The average crystal grain size referred to in the present invention refers to a value obtained by the following Scherer equation from the result of the X-ray diffraction pattern.

D = K · λ / β cos θ Further, the O element in the above formulas (2) to (4) functions as a stabilizer of Bi having a low melting point and precipitates Bi as an oxide, so that it is magnetic. The thermal stability of the property is improved. That is, the O element is an element effective in improving the heat resistance of magnetic properties. If the content of such O element is less than 0.1 at%, the above effect cannot be sufficiently obtained, and if it exceeds 10 at%, on the contrary, the characteristics are deteriorated. The more preferable content of O element is in the range of 0.5 at% to 8 at%, more preferably 0.8 a.
It is in the range of t% to 6at%.

The thermal stability of such magnetic properties is also improved by incorporating an N element as shown in the equation (4). The N element exerts its effect when used in combination with the O element.
The thermal stability improvement effect of N element is 0.01a.
If it is less than t%, it is not sufficiently obtained, while if it exceeds 10 at%, the magnetic permeability decreases. More preferable content of N element is 0.05 at%
~ 9at%, more preferably 0.1at% ~ 8at%
The range is.

The M element in the above equations (3) and (4) is an element effective in improving the soft magnetic characteristics, and its content is set to 0.01 at% to 10 at%. The content of M element is
If it is less than 0.01 at%, the above effect cannot be sufficiently obtained,
If it exceeds 10 at%, the saturation magnetic flux density will decrease. The more preferable content of the M element is in the range of 0.1 at% to 8 at%. In addition, although X element is an element effective in improving the environment resistance, 1
Even if contained over 0 at%, no further effect is seen,
On the contrary, the content may be 10 at% or less because it may deteriorate the soft magnetic properties. Of these X elements, especially A
l, Si, C and white metal elements are effective in improving the environmental resistance.

The soft magnetic alloy thin film of the present invention can be obtained by a usual thin film forming method such as a magnetron sputtering method, an ion beam method, a direct current sputtering method, a vacuum evaporation method and the like. The atmosphere gas at the time of film formation may be Ar or N ₂ which is generally used, but when oxygen is contained in the alloy, the atmosphere at the time of film formation may be an oxygen-containing atmosphere. In view of the above content, the oxygen amount at this time is preferably 10 vol% or less. When forming a film by the sputtering method, a composite target of T element and Bi, or M element or
Use an alloy target with X element added, or use T element and Bi
Place the M element chip and X element chip on the composite target of and sputter.

Since the thin film formed by the above-described film forming method once becomes an amorphous state under normal conditions, it is subjected to heat treatment to precipitate fine crystal grains (average crystal grain size of 50 nm or less) to obtain a desired crystal. Obtain soft magnetic properties. The heat treatment temperature varies depending on the alloy composition, but it is between 350 ℃ and 750 ℃.
The temperature is preferably about ℃ and the heat treatment time is about 5 minutes to 20 hours. The atmosphere during the heat treatment may be Ar or N ₂ , but when oxygen is contained in the alloy, oxygen should be introduced as at least a part of the heat treatment atmosphere if a film is not previously formed in the oxygen-containing atmosphere. Is desirable. Note that it is also possible to crystallize at the film forming stage by controlling the film forming conditions. Even in such a case, fine crystal grains can be obtained.

The soft magnetic thin film of the present invention is suitable as a constituent material for a thin film magnetic head, a plane inductor, and the like. Also,
The thickness of the soft magnetic thin film varies depending on the application, but 1
It is preferably in the range of nm to 10 μm, more preferably in the range of 10 nm to 5 μm. The soft magnetic thin film of the present invention may be used as a single layer film or a multilayer film. When used as a multilayer film, S
Improving soft magnetic characteristics in high frequency range by interposing oxides, nitrides, carbides such as iO ₂ , Si ₃ N ₄ , Al ₂ O ₃ , Al ₃ N ₄ and SiC as an insulating layer You can Further, in order to further improve the saturation magnetic flux density, it can be used as a laminate with an alloy having a higher saturation magnetic flux density than the soft magnetic thin film of the present invention such as Fe, Fe-Si, and iron nitride. is there.

[0020]

EXAMPLES The present invention will be described in detail below with reference to examples.

Example 1 Using a composite target of Fe and Bi, an amorphous thin film of Fe-Bi-O was formed by a high frequency sputtering method in a mixed atmosphere of (Ar + O ₂ ) with an oxygen content of 3 vol%. .. The composition of the thin film was Fe ₈₉ Bi ₉ O ₂ , and the film thickness was 3 μm. Next, this thin film was heat-treated in a nitrogen atmosphere at 500 ° C. for 30 minutes to precipitate crystal grains.

The average crystal grain size of the thin film after the heat treatment was calculated from the X-ray diffraction pattern and found to be 24 nm. Also, 1MHz
The initial permeability and the saturation magnetization were measured using an LCR meter and a sample vibration type magnetometer, respectively. As a result, the initial permeability at 1MHz was 2800, and the saturation magnetization was 17.2kG, which were good values. These values are significantly higher than those of conventional materials such as Sendust alloys and Co-based amorphous alloys.

Example 2 An M element chip and an X element chip were placed on a composite target of Fe and Bi, if necessary, and contained 2 vol% oxygen.
By the high frequency sputtering method in the (Ar + O ₂ ) atmosphere, Table 1
And amorphous thin films having the respective compositions shown in Table 2 were formed. Table 1 and Table 2
Heat treatment was performed under the conditions shown in (1) to precipitate crystal grains. The film thickness and film configuration are as shown in Tables 1 and 2.

[0024]

[Table 1]

[Table 2] The average crystal grain size, the initial magnetic permeability at 1 MHz and the saturation magnetization of each of these soft magnetic thin films were measured in the same manner as in Example 1. The results are shown in Tables 3 and 4.

[0025]

[Table 3]

[Table 4] As is clear from Tables 3 and 4, it is understood that the soft magnetic thin film according to the present invention has both high saturation magnetization and high magnetic permeability. This means that the thin film magnetic head formed by using the soft magnetic thin film of the present invention can sufficiently cope with the high coercive force on the recording medium side.

Comparative Example 1 A thin film having a sendust composition (Fe-Al-Si) in Ar and Co ₇₉ Mo ₉ Zr ₁₀ Cr _{2 were formed by the} same high frequency sputtering method as in the above-described example.
An amorphous thin film having a composition was prepared. The film thickness is 3 μm as in the example. Optimal heat treatment was performed on these thin films, and the initial permeability and saturation magnetization at 1 MHz were measured using an LCR meter and a sample vibrating magnetometer, respectively. as a result,
The sendust thin film had a saturation magnetization of 10.0 kG and an initial magnetic permeability of 2600, and the amorphous thin film had a saturation magnetization of 7.3 kG and an initial magnetic permeability of 2900. In both cases, the initial magnetic permeability is almost the same value, but the saturation magnetization is significantly lower than in the examples.

[0027]

As described above, according to the present invention,
A soft magnetic thin film having a high saturation magnetic flux density, excellent soft magnetic characteristics, and good thermal stability can be obtained. Therefore, it is possible to provide a soft magnetic thin film suitable as a constituent material for a thin film magnetic head, a high frequency compatible planar inductor, and the like.

[0028]

Claims (4)

[Claims] 1. A general formula: T _100-a Bi _a (wherein T is at least 1 selected from Fe, Co and Ni).
A soft magnetic thin film, characterized in that the seed element is an alloy whose composition is substantially represented by a, where a is a number satisfying 1 ≦ a ≦ 20 (at%). 2. A general formula: T _100-ab Bi _a O _b (wherein T is at least 1 selected from Fe, Co and Ni).
A and b are 1 ≤ a ≤ 20, 0.01 ≤ b ≤ 10 (a
The soft magnetic thin film is characterized by comprising an alloy whose composition is substantially represented by (t%). 3. The general formula: T _100-abcd Bi _a M _c X _d O
_b (where T is at least 1 selected from Fe, Co and Ni)
M is at least one element selected from Ti, Zr, Hf, Nb, Ta, W, Mo, Mn and Cr, and X is Al, G
a, In, C, Si, Ge, B, Sb, Pb, Zn, Au, and at least one element selected from the platinum group elements, a, b, c
And d are 1 ≦ a ≦ 20, 0.01 ≦ b ≦ 10, 0.01 ≦ c ≦ 10,
A soft magnetic thin film comprising an alloy whose composition is substantially represented by 0 ≦ d ≦ 5 (at%). 4. The general formula: T _100-abcde Bi _a M _c O _b
X _d N _e (where T is at least 1 selected from Fe, Co and Ni)
M is at least one element selected from Ti, Zr, Hf, Nb, Ta, W, Mo, Mn and Cr, and X is Al, G
a, In, C, Si, Ge, B, Sb, Pb, Zn, Au and at least one element selected from the platinum group elements, a, b,
c, d and e are 1 ≤ a ≤ 20, 0.01 ≤ b ≤ 10, 0.01 ≤ c
A soft magnetic thin film comprising an alloy whose composition is substantially represented by ≦ 10, 0 ≦ d ≦ 5, and 0.01 ≦ e ≦ 10 (at%).