JP2635416B2 - Soft magnetic alloy film - Google Patents

Description

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

[Prior Art] In the field of magnetic recording, a recording medium such as a magnetic tape has been promoted to have a high coercive force in order to increase a 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) with a high saturation magnetic flux density, Fe
-Si-Al alloy (Sendust) is typical,
In recent years, amorphous alloy films mainly composed of Co, which is a ferromagnetic metal element, have been developed.

Further, as a recent attempt, the influence of the magnetocrystalline anisotropy of Fe (the adverse effect on soft magnetism) has been reduced by using an alloy film (Fe-C, Fe-Si, etc.) composed of fine crystals containing Fe as the main component. In some cases, a film having a high saturation magnetic flux density and excellent soft magnetic properties is obtained.

[Problems to be Solved by the Invention] By the way, devices incorporating a magnetic head tend to be reduced in size and weight, and are subject to vibration accompanying movement,
It is increasingly used in adverse environments. Therefore, the magnetic head has excellent magnetic properties and, of course, excellent wear resistance to the magnetic tape,
It is required to have high durability in a temperature or corrosive atmosphere, that is, high environmental resistance and vibration resistance. For this reason, it is necessary to perform the gap formation, the incorporation into the case, and the like 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, among the conventional soft magnetic alloy films, those made of sendust have a saturation magnetic flux density of about 10,000 G (Gauss), which is insufficient for a demand for higher density in the future. In addition, the Co-based amorphous alloy film is 13
Although a high saturation magnetic flux density of 000G or more has been obtained,
In order to increase the saturation magnetic flux density of conventional amorphous alloys, the aluminum-forming elements Ti, Zr, Hf, Nb, Ta, Mo,
It is necessary to reduce the addition amount of W and the like, but if the addition amount is reduced, the stability of the aluminum structure is lowered, and there is a problem that it cannot withstand the temperature required for glass welding (about 500 ° C. or higher).

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,
Since the soft magnetic properties are deteriorated, it is still difficult to say that it is suitable for glass welding.

The present invention solves the above-mentioned problems, and its magnetic properties are thermally stable, have a high saturation magnetic flux density, have small magnetostriction, are excellent in corrosion resistance, and decrease in magnetic permeability due to overcurrent loss. An object of the present invention is to provide a small number of soft magnetic alloy films.

[Means for Solving the Problems] In order to solve the problems, the invention described in claim 1 has a composition formula represented by CoxPdyMzCw, and M is Ti, Zr, Hf, V, Nb,
At least one of Ta, Mo, and W is shown, and the composition ratio is x, y, z, w
Is in atomic%, 50 ≦ x ≦ 96, 0.1 ≦ y ≦ 20, 2 ≦ z ≦ 25, 0.5
≦ w ≦ 25, x + y + z + w = 100, and the entire structure is basically composed of fine crystal grains having an average grain size of 0.05 μm or less, and a part thereof includes a crystal phase of a carbide of the element M.

In order to solve the above problem, the invention described in claim 2 has a composition formula represented by CoxPdyMzCw, and M is Ti, Zr, Hf, V, Nb,
At least one of Ta, Mo, and W is shown, and the composition ratio is x, y, z, w
Is in atomic%, 50 ≦ x ≦ 96, 0.1 ≦ y ≦ 20, 2 ≦ z ≦ 25, 0.5
≦ w ≦ 25, x + y + z + w = 100, and the whole structure basically consists of fine crystal grains with an average particle size of 0.05 μm or less and an amorphous phase. It is included.

 Hereinafter, the present invention will be described in more detail.

As a method of forming the alloy film, the alloy film is sputtered,
It is manufactured by a thin film forming apparatus such as evaporation. As the sputtering apparatus, existing apparatuses such as RF bipolar sputtering, DC sputtering, magnetron sputtering, tripolar sputtering, ion beam sputtering, and facing target type sputtering 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 it, or a method of adding C
The use of a target (Co-Pd-M system) that does not contain, be used methane (CH ₄₎ a reactive sputtering method for sputtering a hydrocarbon gas in mixed gas atmosphere such as such as an inert gas such as Ar In the reactive sputtering method, it is easy to control the C concentration in the film, so that a film having a desired C concentration can be obtained.

Since the film thus produced contains an amorphous phase in a considerable proportion and is unstable,
Microcrystals are precipitated 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. Further, this heat treatment can be performed also as a glass welding step in the manufacturing process of the magnetic head.

The step of depositing the microcrystals does not need to be performed completely, and it is sufficient that a considerable number (preferably 50% or more) of the microcrystals are precipitated. Therefore, the remaining amorphous component does not hinder the improvement of the characteristics.

Hereinafter, the reasons for limiting the components as described above will be described.

Co is a main component and is an element bearing magnetism. In order to obtain a saturation magnetic flux density of at least ferrite (Bs ≒ 5000G) or more, x ≧ 50% is required. Further, in order to obtain good soft magnetic characteristics, x ≦ 96% must be satisfied.

Element M is necessary for improving soft magnetic properties,
Combines with C to form carbide fine crystals. In order to maintain good soft magnetic characteristics, it is necessary to satisfy z ≧ 2%. However, if the amount is too large, the saturation magnetic flux density decreases.
≤ 25%.

C is required for improving soft magnetic properties and improving heat resistance, and combines with the element M to form carbide microcrystals. In order to maintain good soft magnetic properties and thermal stability, it is necessary that w ≧ 0.5%.
Also, if it is too large, the saturation magnetic flux density decreases, so
It is necessary to set w ≦ 25%.

The fine crystals of the carbide of element M act as pinning sites for the magnetic domain walls, have the function of improving the high-frequency characteristics of magnetic permeability, and are uniformly dispersed in the film, so that microcrystals of Co grow by heat treatment and become soft magnetic. It has the function of preventing damage. In other words, when the crystal grains of Co 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 a barrier for the growth of Co grains. Prevent deterioration of magnetic properties.

And, since the metal structure is basically composed of microcrystals of 0.05 μm or less, it is excellent in thermal stability as compared with amorphous, can reduce the number of added elements, and can increase the saturation magnetic flux density. .

Element Pd is an element added for the purpose of adjusting magnetostriction.
When the Pd concentration is low in the CoxPdyMzCw-based alloy obtained by performing the heat treatment, the magnetostriction is a negative value of the order of 10 ⁻⁶ , but the magnetostriction becomes a positive value when the added amount of Pd increases. It is desirable that the magnetostriction be zero in order to minimize the processing distortion due to the processing of the magnetic head and the deterioration of the magnetic characteristics due to the thermal distortion caused by the glass welding. Addition of Pd, which has the effect of causing Pd to be effective, is effective. Also, the upper limit of the amount to be added must be such that the magnetostriction does not exceed +10 ^-5 . If the amount of Pd exceeds 20%, the saturation magnetic flux density is undesirably reduced.

[Function] In the above soft magnetic alloy film, a high saturation magnetic flux density can be obtained because the composition of the soft magnetic alloy film is mainly composed of Co and addition of a component for lowering the saturation magnetic flux density is restricted. In addition, since the element M, Pd and C are contained, and the metal structure is made of fine crystal grains, and the adverse effect on the soft magnetism due to the magnetocrystalline anisotropy is reduced, good soft magnetic properties are obtained. can get. In addition, since the carbide of the element M precipitates and suppresses the growth of the crystal grains containing Co as a main component, in the glass welding step,
Even when heated to 600 ° C. or higher, the crystal grains do not become coarse.

[Examples] Alloy films of various compositions were formed using an RF bipolar sputtering apparatus. For forming the film, C was distributed in the film by sputtering using an alloy target having a composition of Co ₈₆ Ta ₈ Hf ₆ (subscript: atomic%) in a mixed gas atmosphere of Ar gas and CH ₄ gas. .

FIG. 1 shows a change in magnetostriction constant when Pd was added to a film having a composition of Co _79.4 Ta _7.3 Hf _5.0 C _8.3 . This film is amorphous when formed, and the magnetostriction increases in the negative direction with the addition of Pd. However, the magnetostriction is reduced by annealing at 550 ° C. (holding for 20 minutes).
It began to change in the positive direction as the Pd concentration increased. Thus, it was found that a small magnetostriction constant of the order of 10 ^-7 was obtained when Pd was 10 to 18 at%.

FIG. 2 shows a change in coercive force (Hc) with respect to the Pd concentration.
Although the coercive force was slightly increased by the addition of Pd, it did not exceed 10 e, and good soft magnetic characteristics could be maintained.

FIG. 3 shows the electrical resistance (resistivity) of the film with respect to the Pd concentration in the case of the film having a microcrystalline structure obtained by annealing at 550 ° C. Co without Pd addition _79.4 Ta _7.3 Hf _5.0 C _8.3
Is 76 μΩ · cm for a film having the following composition, but the magnetostriction is + 4 × 10
^When about 14at% of Pd is added to become ^-7 , the specific resistance becomes 120μ
Ω · cm. By increasing the specific resistance, the overcurrent loss is reduced, and the magnetic permeability in a high frequency band is improved. The addition of Pd also improves the corrosion resistance.

Table 1 on the next page shows the results of measurement of typical magnetic properties of the alloy films of the present invention. In comparison with the results, typical magnetic properties of conventional Sendust alloy and CoTaHfC-based films without Pd addition are shown. The measurement results of are described.

As is clear from Table 1, the alloy film of the present invention exhibited a higher saturation magnetic flux density than the Sendust alloy film, and exhibited a small magnetostriction constant and a high specific resistance. In addition,
The CoTaHfC-based soft magnetic alloy films shown in Table 1 relate to the invention filed by the present inventors in Japanese Patent Application No. 1-55571. In the above-mentioned prior patent application, 50 ≦ x ≦ 96, 0.1 ≦ y ≦ 20, 2 ≦ z ≦ 2 in the CoxTyMzCw system (T represents one or more of Fe, Ni and Mn).
5, 0.1 ≦ w ≦ 20. In the present invention, Pd is used as the element T to improve the magnetic properties.

[Effects of the Invention] As described in detail above, the present invention is a soft magnetic alloy film composed of fine crystal grains containing Co as a main component, and the addition of a component that lowers the saturation magnetic flux density is limited. A higher saturation magnetic flux density than the alloy film can be obtained.

In addition, the elements M (Ti, Zr, Hf, V, Nb, Ta, Mo, W) and C, which improve the soft magnetism, are added, and the metal structure is composed of fine crystal grains. Since the adverse effect on the soft magnetism due to anisotropy is reduced, good soft magnetic properties can be obtained. Further, since the element M is formed of fine crystal grains and the added element M forms a carbide with C, the crystal grains do not become coarse even when heated to 600 ° C. or more in the glass welding step, and the above-described characteristics are obtained. Since it is maintained, it is suitable as a material for a magnetic head having high performance required for high-density recording.

Furthermore, the addition of Pd provides good corrosion resistance, improves the reliability of the magnetic head, and increases the specific resistance due to the addition of Pd, thereby reducing the decrease in magnetic permeability caused by overcurrent loss at high frequencies. is there.

[Brief description of the drawings]

1 to 3 show the characteristics of various soft magnetic alloy films manufactured in the examples, and FIG. 1 shows Co-Pd-Ta-Hf-C.
2 is a graph showing the relationship between the Pd content and the magnetostriction constant in the alloyed alloy film, FIG. 2 is a graph showing the relationship between the Pd concentration and the coercive force in the alloyed film, and FIG. 3 is the relationship between the Pd concentration and the specific resistance in the alloyed film. FIG.

Claims (2)

(57) [Claims] A composition formula is represented by CoxPdyMzCw, wherein M is Ti, Zr,
At least one of Hf, V, Nb, Ta, Mo, W is shown, and the composition ratio x, y, z, w is atomic% and 50 ≦ x ≦ 96 0.1 ≦ y ≦ 20 2 ≦ z ≦ 25 0.5 ≦ w ≦ 25 x + y + z + w = 100, and the entire structure is basically composed of fine crystal grains having an average grain size of 0.05 μm or less, and a part thereof includes a crystal phase of a carbide of the element M. Soft magnetic alloy film. 2. The composition formula is represented by CoxPdyMzCw, wherein M is Ti, Zr,
At least one of Hf, V, Nb, Ta, Mo, W is shown, and the composition ratio x, y, z, w is atomic% and 50 ≦ x ≦ 96 0.1 ≦ y ≦ 20 2 ≦ z ≦ 25 0.5 ≦ w ≦ 25 x + y + z + w = 100, and the whole structure basically consists of fine crystal grains having an average grain size of 0.05 μm or less and an amorphous phase,
A soft magnetic alloy film characterized in that a part of the structure contains a carbide of the element M.