JP3236277B2 - Method for manufacturing soft magnetic alloy film - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for manufacturing a soft magnetic alloy film suitable for a magnetic head or the like.

[0002]

2. Description of the Related Art In the field of magnetic recording, a recording medium such as a magnetic tape has been developed to have a high coercive force in order to increase the recording density. However, as a material of a magnetic head corresponding thereto, a saturation magnetic flux density (Bs) is required. High things are required.
As a conventional soft magnetic material (film) having a high saturation magnetic flux density, Fe
A typical example is a -Si-Al alloy (Sendust). In recent years, an amorphous alloy film mainly containing Co, which is a ferromagnetic metal element, has been developed. Also, as a recent attempt,
An alloy film (Fe-
(C, Fe—Si, etc.), the effect of the crystal magnetic anisotropy of Fe (the adverse effect on soft magnetism) is reduced by making the crystal finer, and a film having a high saturation magnetic flux density and excellent soft magnetic properties is obtained. There is.

[0003]

By the way, devices incorporating a magnetic head tend to be smaller and lighter, and are often exposed to vibrations associated with movement or used in adverse environments. Has become. Therefore, the magnetic head has excellent magnetic properties and excellent wear resistance to magnetic tapes, as well as high durability in temperature and corrosive atmospheres, that is, high environmental resistance and vibration resistance. Is required. For this reason, it is necessary to form the gap and incorporate the case into the case by glass welding, and the material of the magnetic head needs to be able to withstand the high temperature of the glass welding step in the head manufacturing process.

However, the conventional soft magnetic alloy film made of sendust has a saturation magnetic flux density of about 1
0000G, which is insufficient for a demand for higher density in the future. A Co-based amorphous alloy film having a high saturation magnetic flux density of 13000 G or more has been obtained. However, in order to increase the saturation magnetic flux density of a conventional amorphous alloy, Ti, which is an amorphous forming element, is used.
It is necessary to reduce the addition amount of Zr, Hf, Nb, Ta, Mo, W, etc. However, if these addition amounts are reduced, the stability of the amorphous structure decreases, and the temperature required for glass welding (about 500 ° C.) Above) has an unbearable problem.

Further, the above-mentioned alloy film (Fe—C, Fe—Si, etc.) composed of fine crystals containing Fe as a main component causes crystal growth at a high temperature and deteriorates soft magnetic characteristics (in the case of Fe—C, 400%). (° C. is the maximum), so it is hard to say that it is suitable for glass welding. An object of the present invention is to solve the above problems and to provide a method for producing a soft magnetic alloy film having a small coercive force, a high magnetic permeability, thermally stable characteristics, and a high saturation magnetic flux density.

[0006]

In order to solve the above-mentioned problems, a method of manufacturing a soft magnetic alloy film according to the present invention comprises the steps of:
And one of Ti, Zr, Hf, Nb, Ta, Mo, and W
A thin film containing one or more metal elements M and C and at least a part of which is an amorphous phase is formed, and the thin film is subjected to a heat treatment to precipitate bcc Fe crystal grains and to remove the amorphous phase from the amorphous phase. It is characterized in that fine crystals of carbides of elements M and C are precipitated.
According to the present invention, as the thin film, Fe is contained in an amount of 50 atomic% or more,
A material containing 6 atomic% or less, an element M of 2 atomic% or more and 30 atomic% or less, and a C of 0.5 atomic% or more and 25 atomic% or less can be used.
According to the present invention, as the thin film, in addition to the Fe, the elements M and C, an element T (where T is one of Co and Ni or
Represents two types ), Fe in a range of 50 atomic% or more and 96 atomic% or less, element T of 10 atomic% or less, and element M of 2 atomic% or less.
Range of at least 30 atomic% and at least 0.5 atomic% of C
As described above, those containing each in the range of 25 atomic% or less can be used. Further, the present invention provides that
By performing the heating at a temperature in the range of 0 to 700 ° C., a metal consisting essentially of bcc Fe crystal grains having an average particle diameter of 0.08 μm or less and an amorphous structure, and partially including a crystal phase of a carbide of element M It is characterized as an organization.

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in more detail. As a method for producing the alloy film, the alloy film is produced by a thin film forming apparatus such as sputtering or vapor deposition. As the sputtering apparatus, an existing apparatus such as RF two-pole sputtering, DC sputtering, magnetron sputtering, three-pole sputtering, ion beam sputtering, facing target type sputtering, or the like can be used. As a method of adding C into the film, a method of arranging graphite pellets on a target plate to form a composite target and sputtering the composite target, or using a target containing no C (Fe-TM-based), A reactive sputtering method or the like in which sputtering is performed in a gas atmosphere in which a hydrocarbon gas such as methane (CH ₄ ) is mixed in an inert gas such as Ar can be used. Particularly, in the reactive sputtering method, the C concentration in the film is controlled. Therefore, a film having an excellent C concentration can be obtained.

[0008] The film as-produced in this way contains a considerable proportion of an amorphous phase and is unstable, so that a fine crystal is deposited by performing a heat treatment of heating to about 400 to 700 ° C. By performing this heat treatment in a static magnetic field or a rotating magnetic field, more excellent soft magnetic characteristics can be obtained. This heat treatment can be performed also as a glass welding step in the magnetic head manufacturing process. Note that the step of depositing the fine crystals does not need to be performed completely, and it is sufficient that a considerable number (preferably 50% or more) of the fine crystals are deposited. Therefore, the amorphous component rarely hinders the improvement of the characteristics.

The preferred composition of the soft magnetic alloy film used in the present invention will be described below. Soft magnetic alloy film used in the present invention can be represented by the composition formula Fe _x M _z C _w or _{Fe x T y M z C w} . Fe is a main component and is an element responsible for magnetism. In order to obtain a saturation magnetic flux density of at least ferrite (Bs ≒ 5000G) or more, x ≧ 50 at% is required. In order to obtain good soft magnetic characteristics, x ≦ 9
It must be 6 at%. Element T is an element added for the purpose of adjusting magnetostriction. In the case of the Fe-MC film, when the heat treatment temperature is low, the magnetostriction becomes positive, and when the heat treatment temperature is high, the magnetostriction becomes negative. When a high heat treatment temperature (glass welding temperature) is required, Ni, Co, which has the effect of making magnetostriction positive,
By adding one or two of them in an appropriate amount, the magnetostriction can be reduced to almost zero. In addition, when the heat treatment temperature is appropriate, addition of the element T is not particularly necessary, but addition of T is performed so that the positive magnetostriction does not increase to the order of +10 -5 or more.
y ≦ 10 at% must be satisfied.

The element M is necessary for improving the soft magnetic properties, and combines with C to form fine crystals of carbide. To maintain good soft magnetic properties, z ≧ 2 at%
However, if it is too large, the saturation magnetic flux density decreases, so it is necessary to set z ≦ 30 at%. C is necessary for improving soft magnetic properties and improving heat resistance, and C combines with the element M to form carbide fine crystals. In order to maintain good soft magnetic properties and thermal stability, it is necessary to satisfy w ≧ 0.5 at%. However, if it is too large, the saturation magnetic flux density decreases.
≦ 25 at%.

In particular, in the case of the Fe-MC film, 65 ≦
x ≦ 85, 4 ≦ z ≦ 20, 6 ≦ w ≦ 18, x + z + w =
By limiting the composition ratio to 100, the magnetostriction constant
Within the range of ± 3 × 10 ⁻⁶ , and further excellent soft magnetic characteristics can be obtained. In order to obtain a better fine crystal structure due to uniform generation of crystal nuclei during heat treatment, x ≦ 8 in order to form a film mainly composed of an amorphous phase during film formation.
It must be 5 at%. If the amount of x is too small, not only does the saturation magnetic flux density decrease, but also the concentrations of M and C become too high. If the concentrations of M and C are too high, the volume ratio of the carbide (nonmagnetic phase) of M in the film becomes too high, breaking the exchange coupling between the Fe crystal grains and deteriorating the soft magnetic properties. Therefore, it is necessary to satisfy x ≧ 65 at% in order to obtain better characteristics.

The fine crystals of the carbide of the element M function as pinning sites for the magnetic domain walls, have the function of improving the high-frequency characteristics of magnetic permeability, and disperse uniformly in the film to allow the fine crystals of Fe to grow by heat treatment. It works to prevent soft magnetism from being impaired. In other words, when the crystal grains of Fe grow and grow, the adverse effect of the magnetocrystalline anisotropy increases and the soft magnetic properties deteriorate, but the fine crystals of the carbide of the element M act as barriers for the growth of the Fe grains. Deterioration of characteristics is prevented. Since the metal structure is basically composed of fine crystals having a particle size of 0.08 μm or less, it has excellent thermal stability as compared with amorphous, and can reduce the number of added elements. , The magnetic moment per Fe atom becomes larger, and as a result, the saturation magnetic flux density can be increased. Note that, depending on the application, the value may be out of the range of the numerical limitation.

In the above soft magnetic alloy film, the composition is mainly composed of Fe, and the addition of a component that lowers the saturation magnetic flux density is restricted. Further, the magnetic moment per Fe atom becomes larger than that of an amorphous film. Up to about 180
A high saturation magnetic flux density of 00G can be obtained. Element M
And C are contained, and the metal structure is composed of fine crystal grains, and the adverse effect on the soft magnetism due to the magnetocrystalline anisotropy is reduced, so that good soft magnetic properties can be obtained. Further, since the carbide of the element M precipitates to suppress the growth of crystal grains containing Fe as a main component, the crystal grains do not become coarse even when heated to 600 ° C. or more in the glass welding step. Further, the ratio of elements M and C, M: C is 1: 2
By setting the ratio to 5: 6, the magnetic permeability at 1 MHz becomes 200.
It can be 0 or more.

[0014]

EXAMPLES (Example 1) Fe-Zr of various compositions was obtained by the following two methods using an RF bipolar sputtering apparatus.
The -C film and the Fe-Hf-C film were each formed to a thickness of 5 to 6 m. The first method uses Zr on an Fe target.
Alternatively, reactive sputtering is performed in a mixed gas atmosphere of Ar gas and CH ₄ gas using a composite target formed by appropriately arranging Hf pellets. The second method is Fe
A method of sputtering a composite target in Ar by appropriately arranging Zr or Hf pellets and graphite pellets on the target was adopted. The Zr and Hf concentrations in the film were adjusted by changing the number of Zr and Hf pellets in any method.
The C concentration was adjusted by changing the concentration of CH ₄ gas in the first method, and by changing the number of graphite pellets in the second method. Each of the alloy films thus obtained is subjected to various heat treatments, so that the composition of the alloy film becomes the magnetostriction constant λs and the saturation magnetic flux density B of the soft magnetic alloy film.
s, the influence on the magnetic permeability μ (1 MHz) in the hard axis direction was examined. The results are shown in FIGS.

FIGS. 1 to 3 show Fe—Zr—C
It is a measurement result of a film. FIG. 1 is a graph showing the isothermal lines of the magnetostriction constant and the saturation magnetic flux density of the alloy film after the heat treatment at 550 ° C. for 20 minutes. In FIG. 1, the solid line indicates an isoline of the magnetostriction constant (λs), and the broken line indicates the saturation magnetic flux density (B
FIG. 9 shows contour lines of s). FIG. 2 shows that in a static magnetic field, 55
5 is a graph showing isolines of magnetic permeability in the direction of hard axis at 1 MHz after the heat treatment at 0 ° C. for 20 minutes. FIG. 3 is a graph showing the isothermal lines of the magnetostriction constant and the saturation magnetic flux density of the alloy film after the heat treatment at 650 ° C. for 20 minutes. In FIG. 3, the solid line shows the isoline of the magnetostriction constant, and the broken line shows the isoline of the saturation magnetic flux density.

FIG. 4 shows the measurement results of the Fe—Hf—C film, which shows the permeability of the alloy film in the hard axis direction at 1 MHz after a heat treatment at 550 ° C. for 20 minutes in a static magnetic field. It is the graph which showed the contour line. In FIGS. 1 to 4,
The marks indicate those which were made amorphous in the as-deposited state, and the marks ● indicate those which were not made amorphous. An optical lever method was used to measure the magnetostriction constant, a figure-eight coil type permeance meter was used to measure the magnetic permeability, and a vibrating sample type magnetometer was used to measure the saturation magnetic flux density. From FIG. 1 to FIG. 4, Fe-MC (M = Zr, H
f) The effect of the alloy composition of the film on the soft magnetic properties was examined.

FIG. 1 shows that when the heat treatment is performed at 550.degree. C., the magnetostriction constant becomes almost 0 when the composition is approximately 1: 1 with Zr: C. Further, when heat treatment at 650 ° C. is performed as shown in FIG. 3, there is a composition in which the magnetostriction constant becomes almost 0 at a composition slightly higher in C concentration than in FIG. 1, and λs = 0 even at 550 ° C. or 650 ° C. I was able to confirm. Further, from FIGS. 2 and 4, it can be seen that all of the alloy films having high magnetic permeability were amorphous in the film-forming state regardless of the type of M. That is, it was confirmed that unless the crystallization was performed from an amorphous state, uniform crystal nuclei would not be generated, and it would be difficult to obtain a uniform and favorable fine crystal structure. In particular, the composition at which the magnetic permeability at 1 MHz is 2000 or more is M (M = Zr,
HF): C was found to be distributed in a composition region of about 1: 2 to 5: 6. Further, as can be seen from the saturation magnetic flux density Bs contour lines shown in FIGS. 1 and 3, it was confirmed that the upper limit of Bs of such a film was about 17 to 18 kG. Therefore, it can be confirmed from FIGS. 1 to 4 that a composition having low magnetostriction constant and high magnetic permeability and exhibiting magnetic characteristics is present.

Next, by the reactive sputtering, the Fe
The _78.7 Zr _5.3 C _16.0 film and Fe _{81. 8} Hf _5.4 C _13.5 film heat-treated at each 20 minutes at each temperature to examine the change in the magnetostriction constant by a change in annealing temperature. The result is shown in FIG. In FIG. 5, ● shows the measurement results of the Fe _78.7 Zr _5.3 C _16.0 film, and ○ shows the measurement results of the Fe _81.8 Hf _5.4 C _13.5 film. The data in parentheses does not saturate at the applied magnetic field of 100 Oe. It is a thing. As shown in FIG. 5, the magnetostriction constant changes from positive to negative as the heat treatment temperature increases.
It was confirmed that the heat treatment at で 630 ° C. resulted in 0. Therefore, based on the data shown in FIGS. 1 to 5, the magnetostriction constant .lambda.s of the alloy film is 0. +-. 3.times. Under any heat treatment conditions at or above the minimum temperature (about 400 to 500.degree. In order to fall within the range of 10 ^-6 , the alloy composition is adjusted to Fe _x M _z C _w (65 ≦ x ≦ 85, 4 ≦ z ≦ 20,
6 ≦ w ≦ 18 (at%)). When not limit the magnetostriction constant λs especially 0 ± 3 × 10 ^-6, the alloy composition _{Fe x M z C w (50} ≦ x ≦
96, 2 ≦ z ≦ 30, 0.5 ≦ w ≦ 25 (at%)).

Example 2 An alloy film having the composition shown in Table 1 was formed to a thickness of 5 to 6 μm using an RF bipolar sputtering apparatus. This includes Zr, Ta, Hf, C on a Fe target.
A method was employed in which sputtering was performed in a mixed gas atmosphere of Ar gas and CH ₄ gas using a composite target constituted by appropriately arranging pellets of o. After film formation, 55
Hold at 0 ° C for 20 minutes or 550 in the absence of magnetic field
Hold at ℃ for 20 minutes or 650 ℃ in the absence of magnetic field
For 20 minutes. The saturation magnetic flux density (Bs) of the alloy film manufactured as described above and the sendust alloy film formed by sputtering (comparative example) after the heat treatment.
And the magnetic permeability (μ) and the coercive force (Hc) and the magnetostriction (λs) were measured. The above results are also shown in Table 1.

[0020]

[Table 1]

Sample A in Table 1 showed a much higher saturation magnetic flux density (17300 G) than the Sendust film. Here, in a conventional amorphous alloy generally showing a saturation magnetic flux density of 13000 G or more, those having a high saturation magnetic flux density are treated under the same conditions (550 ° C., 2 ° C.).
(Time heating), and the magnetic permeability decreases to 100 or less. That is, in the amorphous alloy film, the magnetic characteristics after glass deposition are deteriorated, and satisfactory characteristics as a magnetic head cannot be obtained. Therefore, it is clear that Sample A of the present invention is an excellent alloy film showing high magnetic permeability even when subjected to a high-temperature heat treatment.

Further, the film of sample A was subjected to heat treatment in a static magnetic field at 550.degree.
z) was 3620, and the coercive force was 0.35 Oe, showing extremely excellent soft magnetic properties. Samples B and C have high saturation magnetic flux densities of 15600 G and 14900 G, respectively, indicating higher magnetic permeability than Sample E of the sendust film.
These films can obtain high magnetic permeability even in a heat treatment in the absence of a magnetic field, and have characteristics that cannot be realized by a conventional amorphous film having a high saturation magnetic flux density. That is, since the amorphous film tends to have induced magnetic anisotropy due to the directional regular arrangement of magnetic atoms and the like, there is a disadvantage that the soft magnetic property is greatly deteriorated due to the fixation of the magnetic domain in the heat treatment in a magnetic field below the Curie point. . Therefore, by using the alloy of the present invention, glass welding and the like can be performed in a magnetic head manufacturing process without a magnetic field, and the process can be simplified.

The films of Sample B and Sample C are 550
+ 2.8 × 10 ^-6 and +2.1 after heat treatment at
It is a positive magnetostriction constant of × 10 ^-6 , but the heat treatment temperature is 650.
° C to -0.3 × 1 each
0 ⁻⁷ and + 0.4 × 10 ⁻⁷ , and a magnetostriction close to 0 can be obtained. In other words, in the manufacturing process of the magnetic head, the reverse magnetostriction effect acts due to the processing strain and the thermal strain applied in the glass welding process. However, when the magnetostriction is small as described above, the film does not impair the soft magnetic characteristics due to the reverse magnetostriction effect. Furthermore, while the magnetostriction constant of a conventional Fe-based amorphous alloy (made by a liquid quenching method) is as large as about + 2 × 10 ⁻⁵ , the films of Samples A, B, C, and D achieve low magnetostriction. it can.

In Table 1, Sample D is Sample A.
The magnetostriction is adjusted by adding Co to the alloy of
This film has a low magnetostriction after the heat treatment at 650 ° C. Co has a function of increasing the saturation magnetic flux density in addition to the action of adjusting the magnetostriction, and the film of sample D has a high saturation magnetic flux density of 17,600 G. 6 and 7 are graphs showing the frequency characteristics of the magnetic permeability of the films of Sample A and Sample C in Table 1, respectively. All the samples showed extremely high magnetic permeability, and even in a high frequency region around 10 MHz
A magnetic permeability of about 2300 is obtained. It has been found that even when heat treatment is performed in a static magnetic field as shown in FIG. 6, heat treatment at a high temperature of 600 ° C. is possible while maintaining high magnetic permeability as shown in FIG.

Next, X-ray diffraction measurement was performed to identify the metal structure of the alloy film. In the film of sample C, the X-ray diffraction pattern of the film as-formed and 5
Diffraction pattern of film after heat treatment at 50 ° C for 20 minutes and 65
FIG. 8 shows the diffraction pattern of the film after heat treatment at 0 ° C. for 20 minutes. The halo pattern shown in FIG. 8 is almost amorphous. In this state, a sufficient saturation magnetic flux density cannot be obtained, and the soft magnetism is also insufficient. FIG.
In this pattern, an amorphous halo pattern also slightly remains, but bcc (body-centered cubic structure) Fe (1
10) A diffraction peak and a slightly weaker TaC diffraction peak appear, indicating that the structure is a mixture of an amorphous phase and a crystalline phase. Each of the diffraction peaks of the crystal phase in the pattern (b) is broad, indicating that the crystal grains are fine. The crystal grain size of bcc-Fe calculated from the half width of the diffraction peak is about 60 to 70 °. When this film is heat-treated at a higher temperature, the whole film has a structure composed of microcrystals as shown in a diffraction pattern. In each case, it was confirmed that a high saturation magnetic flux density and excellent soft magnetic characteristics were exhibited.

[0026]

As described above, according to the present invention, Fe as the main component, one or more metal elements M of Ti, Zr, Hf, Nb, Ta, Mo and W, and C are used. A thin film containing at least a part thereof in an amorphous phase is formed, and this thin film is subjected to a heat treatment to precipitate bcc Fe crystal grains and to precipitate fine crystals of a carbide of the element M from the amorphous phase. Since the soft magnetic alloy film thus obtained has a metal structure basically composed of fine crystals of bcc Fe, it has excellent thermal stability as compared with an amorphous alloy, and has a small number of additional elements. Can be
Further, since the magnetic moment per Fe atom is larger than that of the amorphous alloy, the saturation magnetic flux density is higher than that of the sendust alloy film, and the maximum is about 1800.
A high saturation magnetic flux density of 0 G can be obtained. Further, unlike a conventional amorphous alloy film, a film exhibiting a high saturation magnetic flux density and a high magnetic permeability can be obtained even when heat treatment is performed in the absence of a magnetic field.

As the thin film used in the above-mentioned manufacturing method, Fe is in the range of 50 at% to 96 at%, element M is in the range of 2 to 30 at%, C is 0.5 at% or more, It is preferable to use ones each containing 25 atomic% or less. Further, as the thin film element T (where T in addition to Fe and element M and C Co, of Ni
One or two types ), Fe in a range of 50 atomic% or more and 96 atomic% or less, element T of 10 atomic% or less,
It is preferable to use one containing the element M in the range of 2 to 30 atomic% and C in the range of 0.5 to 25 atomic%. Further, by performing the heat treatment at a temperature in the range of 400 to 700 ° C., the heat treatment is basically made of bcc Fe crystal grains having an average grain size of 0.08 μm or less and an amorphous structure. A soft magnetic alloy film having a metal structure containing a crystal phase can be obtained.

[Brief description of the drawings]

FIG. 1 is a graph showing the composition dependence of the magnetostriction constant and the saturation magnetic flux density of an Fe—Zr—C alloy film of the present invention when subjected to a heat treatment at 550 ° C.

FIG. 2 is a graph showing the composition dependency of the magnetic permeability of the Fe—Zr—C alloy film of the present invention when subjected to a heat treatment at 550 ° C.

FIG. 3 shows Fe—Zr when heat-treated at 650 ° C.
4 is a graph showing the composition dependence of the magnetostriction constant and the saturation magnetic flux density of a -C alloy film.

FIG. 4 shows Fe—Hf when heat-treated at 550 ° C.
5 is a graph showing the composition dependency of the magnetic permeability of a -C alloy film.

FIG. 5 shows that Fe—Zr— when the heat treatment temperature is changed.
5 is a graph showing changes in magnetostriction constants of a C alloy film and an Fe—Hf—C alloy film.

FIG. 6 is a graph showing frequency characteristics with respect to magnetic permeability in one embodiment of the present invention.

FIG. 7 is a graph showing frequency characteristics with respect to magnetic permeability of another embodiment of the present invention.

FIG. 8 is a graph showing an X-ray diffraction pattern performed for identifying a metal structure of a film according to an example of the present invention.

Claims (4)

(57) [Claims] 1. A main component of Fe, Ti, Zr, Hf, and N
b, Ta, Mo, W, a thin film containing one or more metal elements M and C and having at least a part thereof in an amorphous phase is formed, and the thin film is subjected to a heat treatment to obtain a bcc film. Fe
Of the element M from the amorphous phase.
A method for producing a soft magnetic alloy film, comprising: depositing a fine crystal of carbide. 2. The thin film according to claim 1, wherein Fe is in a range of 50 atomic% to 96 atomic%, and element M is 2 atomic% to 3 atomic%.
2. The method for producing a soft magnetic alloy film according to claim 1, wherein a material containing C in a range of 0 at% or less and C in a range of 0.5 at% or more and 25 at% or less is used. 3. The thin film contains an element T ( one or two of Co and Ni) in addition to Fe, elements M and C, and contains Fe in a range of 50 atomic% or more and 96 atomic% or less; It is characterized by using an element containing 10% by atom or less of element T, 2% by atom or more and 30% by atom or less of element M, and C containing 0.5% by atom or more and 25% by atom or less. A method for producing a soft magnetic alloy film according to claim 1. 4. By performing the heat treatment at a temperature in the range of 400 to 700 ° C., the heat treatment is basically composed of bcc Fe crystal grains having an average grain size of 0.08 μm or less and an amorphous structure, and a part of the A soft magnetic alloy film having a metal structure containing a carbide crystal phase.