JPH0827908B2 - Magnetic head - Google Patents

Description

TECHNICAL FIELD The present invention relates to a magnetic head such as a VTR and a method for manufacturing the same.

Conventional technology Conventionally, an amorphous alloy such as Fe-Si-Al (sendust) alloy or Co-Nb-Zr is used near the magnetic gap, and a metal-in-gap (MI) that uses Mn-Zn ferrite for the back core.
G) The head is known. This is the saturation magnetic flux density (4πM
By using a head having a structure in which a metal magnetic alloy film having a high s) is located in the vicinity of the magnetic gap, the recording characteristics are mainly improved as compared with a magnetic head made of a single ferrite. FIG. 2 shows an example of such a MIG type head. In the figure, 1 is a ferrite back core, 2
Is a metal magnetic alloy film, 3 is a magnetic gap part made of SiO ₂ or the like, and 4 is a core bonding glass part.

Problems to be Solved by the Invention However, as a magnetic metal film of a head having such a structure, a Fe--Si--Al-based alloy or Co--Nb--Zr-based amorphous alloy that has been conventionally used as a head core material is used. If used, Al segregates at the interface 5 between the metal magnetic film portion 2 and the ferrite core portion 1 shown in FIG. 1, or Nb, Zr, etc. deprive the ferrite of oxygen to form an altered layer, which causes pseudo There is a problem that it becomes a gap and impairs the characteristics of the head. Fe-Si
-Al-based alloy film is difficult to control the magnetic anisotropy, and variations in characteristics are likely to occur when made into a head. Co-Nb-Zr-based amorphous alloy film can control the magnetic anisotropy by heat treatment in a magnetic field. However, the anisotropy disappears unless all the heat treatment steps are performed in a magnetic field, and the one with high saturation magnetization has the problem that the crystallization temperature is low and the glass bonding step near 500 ° C is difficult. was there.

The present invention aims to solve such problems of the conventional technology.

Means for Solving the Problems A magnetic head according to the present invention uses an alloy film T _a M _b X _c N _d having the composition expressed by the following formula in a metal alloy film portion, using an alteration layer (1). To reduce

However, T is at least one metal selected from the group consisting of Fe, Co, and Ni, and M is at least one metal selected from the group consisting of Nb, Zr, Ti, Ta, Hf, Cr, Mo, W, and Mn. Metal, X is B, S
At least one semi-metal / semiconductor selected from the group consisting of i and Ge, N is nitrogen and a, b, c and d are atomic percentages, and 65 ≦ a ≦ 93 (2) 4 ≦ b ≦ 20 (3) 1 ≦ c ≦ 20 (4) 2 ≦ d ≦ 20 (5) a + b + c + d = 100 (6)

Further, in the present invention, the vicinity of the gap is represented by the following formula T _a M _b X _c N _d , where T is at least one metal selected from the group consisting of F _e , C _o and N _i , and M is N _b , At least one metal selected from the group consisting of Z _r , T _i , T _a , H _f , C _r , M _o , W, M _n , X is B,
At least one semi-metal / semiconductor selected from the group consisting of S _i and G _e , N is N (nitrogen), a, b, c and d represent atomic percentages, and 65 ≦ a ≦ 93 4 ≤ b ≤ 20 1 ≤ c ≤ 20 2 ≤ d ≤ 20 a + b + c + d = 100) in the method of producing a magnetic head in which the other core part is mainly composed of ferrite. , The alloy film is deposited on a ferrite substrate by a sputtering method or the like, and a magnetic field is applied in a direction substantially parallel to the surface of the alloy film to be the magnetic gap surface and at a direction substantially perpendicular to the depth direction of the magnetic gap. After the heat treatment at the Curie temperature or higher of the ferrite substrate, a usual head fabrication process is performed to configure a magnetic head so that the ferrite substrate serves as a back core and the alloy film portion serves as a front core including a magnetic gap surface. Of the magnetic head It is a production method.

Further, in the method of manufacturing the magnetic head of the present invention, the characteristics of the manufacturing process of the MIG head are utilized, and in a state where the demagnetizing field coefficient is small, the magnetic gap surface of the alloy film is approximately parallel to the magnetic gap surface, and the depth of the magnetic gap is substantially the same. A magnetic field is applied in a direction substantially perpendicular to the direction, and heat treatment is performed at the Curie temperature of the ferrite substrate or higher.

Action In the above structure, by using a special nitride alloy film for the magnetic alloy film portion, the reaction with the ferrite back core portion is reduced, so that an altered layer is less likely to occur and the problem of pseudo gap is improved. Further, the above-mentioned heat treatment makes it possible to improve the high frequency characteristics of the magnetic head and make the characteristics uniform.

Embodiments Embodiments of the present invention will be described below with reference to the drawings.

In the formula (1), a ≦ 94,5 ≦ b + c (7) is necessary for the alloy film to exhibit soft magnetism, and 65 ≦ a, b ≦ for the alloy film to have a high saturation magnetization. 20, c ≦ 20 (8) is desirable. Further, it was found that 2 ≦ d 2 (9) is necessary to prevent the reaction with ferrite and the pseudo gap is reduced, and more preferably 3 ≦ c + d 3 (10). Further, in order to prevent nitrogen from being dissociated from the film by heat treatment, 4 ≦ b (11) is necessary. In order to suppress internal stress of the alloy film and prevent the film from peeling from the substrate, d ≦ 20 … (12) is desirable. From equations (7)-(12) above, (2)
The conditional expression of- (6) was obtained.

In order to further improve the soft magnetic properties of this nitrided alloy film, the nitrided alloy film T _a ′ M _b ′ X _c ′ N _d ′, ... It is desirable to use 1 '). However, T, M, X, and N are the same as those described in formula (1), and a ′, b ′, c ′, and d ′ are the average compositions of the respective constituent elements that fluctuate in the film thickness direction and are expressed in atomic percent. 65 ≦ a ′ ≦ 93 (2 ′) 4 ≦ b ′ ≦ 20 (3 ′) 1 ≦ c ′ ≦ 20 (4 ′) 2 ≦ d ′ ≦ 20 (5 ′) a ′ + B '+ c' + d '= 100 (6'), and the reason for limitation is the same as in (2)-(6). Such a composition-modulated film (including a laminated structure film in a broad sense) exhibits excellent soft magnetism, and as a manufacturing method, a nitride layer and a non-nitride layer are laminated by a reactive sputtering method in which nitrogen gas is periodically mixed. By doing so, a laminated structure is obtained, and by heat treating this film, a composition-modulated structure or a laminated structure is obtained. In conventional amorphous alloys, active Nb, Zr, etc. deprived ferrite of oxygen at the interface to form an altered layer, but in these nitride alloy films, Nb, Zr, etc. are selectively bonded to nitrogen. Therefore, an altered layer is less likely to occur. At the same time, in the formula (1) or (1 '), these M elements, that is, Nb, Zr, Ti, Ta, Hf, etc. have a large binding force with nitrogen, so that nitrogen is dissociated from the film even at high temperature heat treatment. It contributes to the stability of the film quality and various properties of the film. In the formula (1) or (1 '), the X element does not deprive the ferrite of oxygen like the M element does, but combines with nitrogen to suppress the reaction between the ferrite and the magnetic alloy film and contribute to the reduction of the pseudo gap. .

Since these nitride alloy films are thermally stable unlike conventional amorphous alloys, high temperature heat treatment at 500 ° C or higher is possible.
Unlike crystalline alloys such as Fe-Si-Al, this nitrided alloy film can control magnetic anisotropy by heat treatment in a magnetic field, and once anisotropy is obtained by heat treatment in a magnetic field at high temperature. This magnetic anisotropy is difficult to disappear by heat treatment at a lower temperature than that even in a magnetic field. In the present invention, focusing on the characteristics of the nitrided alloy film and the fact that the MIG head manufacturing process is suitable for heat treatment in a magnetic field, a method of manufacturing a magnetic head having excellent high frequency characteristics and uniform characteristics was developed.

An example of the method of manufacturing the magnetic head of the present invention will be described below with reference to FIG.

A magnetic head having a structure usually called a metal ingap is manufactured through the processing steps shown in FIG. 1 in the figure
Those corresponding to the symbol -4 are the same as those in FIG. In this case, the magnetic path of the magnetic head in FIG.
It is desirable in terms of characteristics that it is configured to mainly pass through the XZ plane around the winding hole 6 and has an easy axis of magnetization in the Y direction. However, it is difficult to impart magnetic anisotropy in this direction even if a heat treatment is performed by applying a magnetic field in this direction in this shape. The reason for this is that the dimensions of the magnetic alloy film portion 2 in the X, Y and Z directions are almost the same.
The demagnetizing field coefficient with respect to the direction is extremely large, and a magnetic field of several thousand Oe is required to overcome this, which is difficult in the actual process. However, when the shape is as shown in FIG. 1A or 1B, that is, the state in which the nitride alloy film 2 is vapor-deposited on the ferrite substrate 1 by the sputtering method or the like, or the state in which the XY plane is polished to form the gap plane. In (b), the magnetic field is applied in the Y direction in the figure, that is, in the direction parallel to the gap surface 3'and perpendicular to the depth direction X of the gap, and heat treatment is performed at the Curie temperature of the ferrite substrate or higher. It is possible to attach it to. At this time, the diamagnetic field coefficient in the Y direction of the magnetic alloy film portion is small, and the applied magnetic field of several hundred Oe is sufficient. Since the Curie temperature of ferrite is 300 ° C or lower, if the heat treatment is performed at a temperature higher than this temperature, the demagnetizing field of the ferrite substrate will not contribute at all. The magnitude of magnetic anisotropy in the Y direction can be arbitrarily controlled by combining heat treatment in a fixed magnetic field in the Y direction with heat treatment in a rotating magnetic field in the XY plane, that is, in the gap plane. is there. Next, half of the bar shown in FIG. 7B is subjected to the winding groove processing as shown in FIG.
After forming the gap material 3 such as S _i O ₂ to the gap surface 3 ',
The glass 4 joins the cores shown in (b) and (b ') to obtain a magnetic head as shown in (c).
Since this glass bonding is usually performed near 480 ° C, if the above-mentioned heat treatment in a magnetic field is set to be higher than this temperature and performed at 500 to 650 ° C, the magnetic anisotropy applied in the Y direction will be in this non-magnetic field. It will not be lost by the glass bonding process. Since conventional amorphous alloys have difficulty in thermal stability at 500 ° C or higher, such a heat treatment process in a high temperature magnetic field is impossible.

The magnetic head manufactured in this manner exhibits excellent characteristics. This is because the magnetic alloy film portion near the gap can have ideal magnetic anisotropy. If this magnetic anisotropy is too large, the high frequency characteristics will be improved, but the magnetic permeability of the alloy film will decrease and the reproduction efficiency of the head will deteriorate, so it is necessary to optimize the heat treatment conditions in the magnetic field. It is possible to control the magnetic anisotropy to an arbitrary size by adjusting the heat treatment time / temperature and combining heat treatment in a fixed magnetic field and a rotating magnetic field.

The effects of the present invention will be described below with reference to specific examples.

<Example 1> A thickness of 8 µ was formed on a Mn-Zn ferrite substrate by a sputtering method.
An Fe-Si-Al alloy film and a Co-Nb-Zr amorphous alloy film having a thickness of m were formed to prepare a MIG type magnetic head as shown in FIG. Next, the target is Co-Mn-Nb-B and Fe-Nb.
-Si-B alloy plate was used, and N ₂ gas was mixed with Ar gas and sputtered to form Co ₇₀ Mn ₆ Nb ₇ B ₁₅ N ₂ and Fe ₇₆ N.
b ₈ Si ₂ B ₁₂ N _{2 with} a thickness of 8 μm as a nitride alloy film is similarly formed by Mn-Zn.
It was formed on a ferrite substrate. Further, by using the above target and periodically mixing N ₂ gas into Ar gas during sputtering, Co-Mn-Nb-B / Co-Mn-Nb-BN and Fe
-Nb-Si-B / Fe-Nb-Si-B-N composed of a non-nitrided layer and a nitrided layer with a total thickness of 8 μm.
It was formed on an n-Zn ferrite substrate. At this time, the average film composition was changed to <Co ₇₀ Mn ₆ Nb ₇ by changing the partial pressure ratio of N ₂ gas.
B ₁₅ N ₂ >, <Co ₆₆ Mn ₆ Nb ₆ B ₁₄ N ₈ >, and <Co ₆₃ Mn ₅ Nb ₅ B
₁₃ N _14>; to give the _{<Fe 76 Nb 8 Si 2 B} 12 N 2><Fe 72 Nb 7 Si 2 B 11 N 8> and _{<Fe 68 Nb 6 Si 2 B} 10 N 14>. In this way Mn-Zn
Using various nitride alloy films formed on the ferrite substrate,
A MIG type magnetic head was manufactured through the steps shown in FIG. In the process of FIG.
Heat treatment at 520 ° C for 1 hour, at this time a magnetic field of 500 Oe fixed from the outside and applied in the Y direction, fixed in the Y direction for 30 minutes and rotated in the XY plane for 30 minutes, and magnetic field applied Three types of heat treatments, which were performed without heat treatment, were performed. The glass bonding process shown in FIG. 3C was performed at 480 ° C. in a magnetic field. The various magnetic heads manufactured as described above were attached to an ordinary VTR deck, and their characteristics were compared using a metal tape. The magnetic gap and track width of all heads were unified to 0.25 μm and 20 μm, respectively. The results are shown in Table 1.

From the experimental results shown in Table-1, it can be seen that the magnetic head having the structure of the present invention reduces the waviness of the reproduction output caused by the influence of the pseudo gap, and the problems of the prior art are greatly improved. Further, it is found that the composition-modulated nitride alloy film is more advantageous in reproducing output than the single-layer nitride alloy film. Further, the head manufactured by using the heat treatment process in the magnetic field of the present invention exhibits excellent characteristics. Particularly, the head heat-treated in the fixed magnetic field is excellent in the frequency characteristic of reproduction output, and the heat treatment in the fixed magnetic field and the heat treatment in the rotating magnetic field are performed. It can be seen that the combination of the above shows a high reproduction output.

<Example 2> As a target, Co-Nb-Zr-B, Co-Nb-Hf-B, Co-Ti
-Ta-B, Co-Mo-Cr-Zr-B, Co-Nb-B, Fe-Nb-Si, Fe
Using -Ni-W-Nb-Ge, a composition-modulated nitride alloy film consisting of a nitride layer and a non-nitride layer was formed on the Mn-Zn ferrite substrate by the reactive sputtering method in the same manner as in Example 1. The total film thickness is 8 μm, the composition modulation wavelength and the nitrogen content are N ₂
It was changed by controlling the gas mixing period and the partial pressure ratio. Using these, a MIG type magnetic head was manufactured by the same method as in Example 1, and its various characteristics were measured by the same method. However, the heat treatment was performed at 600 ° C. for 30 minutes in the fixed magnetic field and for 15 minutes in the rotating magnetic field. Table 2 shows the results.

The relative reproduction output ratio in the table is that of the Fe-Si-Al head in Table-1.
The comparison was performed with 0db.

From the results shown in Table-2, it is shown that the swelling of the reproduction output due to the pseudo-gap is reduced by nitriding, and that the greater the nitrogen content of the alloy film, the greater this effect is. You can see from the result. Further, it is understood that if the composition modulation wavelength (= layer thickness of one nitrided layer + layer thickness of one non-nitrided layer) becomes too long, the reproduction output of the head tends to decrease.

EFFECTS OF THE INVENTION As described above, the present invention reduces the problem of the pseudo gap peculiar to the MIG head and enables a magnetic head having excellent frequency characteristics.

[Brief description of drawings]

FIG. 1 is a process diagram showing an example of a method for manufacturing an MIG type head of the present invention, and FIG. 2 is a front view showing an example of a conventional MIG type magnetic head having a simple structure. 1 ... Ferrite, 2 ... Magnetic alloy film, 3 ... Magnetic gap, 4 ... Bonding glass, 5 ... Interface between magnetic alloy film and ferrite core, 6 ... Winding hole.

Claims (2)

[Claims] 1. A MIG having a back core made of ferrite and a magnetic alloy film in the vicinity of a magnetic gap, and an interface between the ferrite and the magnetic alloy film being substantially parallel to the magnetic gap surface.
In a (metal-in-gap) type magnetic head, the following formula TaMbXcNd (where T is at least one metal selected from the group consisting of Fe, Co and Ni, M is Nb, Zr, Ti, Ta, Hf) , Cr, Mo,
At least one metal selected from the group consisting of W and Mn,
X is at least one semi-metal / semiconductor selected from the group consisting of B, Si and Ge, N is nitrogen, a, b, c and d represent atomic percentages, and 65 ≦ a ≦ 93,4 respectively. ≤ b ≤ 20, 1 ≤ c ≤ 20, 2 ≤ d ≤ 20, a + b + c
+ D = 100) The magnetic head is characterized by using a magnetic alloy film having a composition shown by (4). 2. A magnetic alloy film in the vicinity of a magnetic gap is composition-modulated in the film-forming direction and has the following formula Ta'Mb'Xc'Nd '(where T is at least selected from the group consisting of Fe, Co and Ni). One kind of metal, M is Nb, Zr, Ti, Ta, H
At least one metal selected from the group consisting of f, Cr, Mo, W and Mn, X is at least one semi-metal / semiconductor selected from the group consisting of B, Si and Ge, and N is nitrogen. , A ′,
b ', c', d'represent atomic percentages, and 65≤a'≤93, 4≤b'≤20, 1≤c'≤20, 2≤d'≤20,
a '+ b' + c '+ d' = 100).
The magnetic head described.