JPH0935208A - Magnetic head and its production - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent counter diffusion at the interface between a ferrite core and a magnetic alloy film, to stably regulate a pseudo gap to a practical level or below and to obtain a magnetic head at a low cost in a high yield. SOLUTION: A film having an average compsn. of the entire film represented by the formula T<x> My Nz (where T is Fe or Co, M is at least one kind of metal selected from among Nb, Zr, Ta, Hf, Cr, W and Mo, N is nitrogen, 65<=x<=94at.%, 5<=y<=25at.% and 0<z<=20at.%) is used as the magnetic alloy film 2 of an MIG head. The concn. of nitrogen in a magnetic alloy film 5 within 0.5μm from the surface of a ferrite core 1 is made 2-10 times the concn. of nitrogen in the entire magnetic alloy film 2.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetic head of a magnetic recording / reproducing apparatus such as a VTR and a method of manufacturing the same.

[0002]

2. Description of the Related Art At present, as a magnetic head of a magnetic recording / reproducing apparatus represented by a VTR, a magnetic alloy film (Fe-S) having a high saturation magnetic flux density is provided near a magnetic gap of a ferrite head.
i-Al, Fe-Ta-N, etc.), so-called M
The mainstream is the et al-in-Gap head (hereinafter, referred to as MIG head). In this method, a magnetic alloy film is formed on a ferrite core by a thin film forming method such as sputtering, and it is intended to improve recording characteristics while utilizing the good reproduction characteristics of a conventional ferrite head.

FIG. 4A shows the structure of a magnetic head having the simplest structure as an example of such an MIG head. In the figure, 1 is a ferrite back core, 2 is a magnetic alloy film, 3 is a magnetic gap made of SiO ₂ or the like, and 4 is glass for joining cores.

[0004]

However, in the magnetic alloy film 2 of the magnetic head having such a structure, Fe--Si--
When an alloy such as Al or Fe-Ta-N is used, the ferrite back core 1 is heat-treated in the magnetic head manufacturing process.
There is a problem that mutual diffusion (in particular, oxygen in ferrite diffuses into the magnetic alloy film) occurs at the interface between the magnetic alloy film 2 and the magnetic alloy film 2 to form a non-magnetic layer having a significantly reduced magnetic permeability.

FIG. 4B shows a ferrite core and Fe after heat treatment (500 ° C., 1 hour) by Auger electron spectroscopy.
The depth profile of the interface diffusion state with a -Ta-N alloy film (only the signals of Fe, N, and O are extracted) is shown. As can be seen from the figure, oxygen is diffused in the magnetic alloy film 2 and the interface is parallel to the magnetic cap 3, so that a pseudo gap (pseudo signal: about 5 to 10 dB) is formed,
This will impair the characteristics of the magnetic head. The practical level is
The pseudo signal is 1 dB or less.

To solve this problem, magnetic heads having the structures shown in FIGS. 5 and 6 have been devised and put into practical use. In the magnetic head of FIG. 5, the problem of the pseudo gap is avoided by tilting the interface between the ferrite back core 1 and the magnetic alloy film 2 with respect to the magnetic gap 3. However, in such a configuration, since the magnetic alloy film 2 is inclined, it is difficult to regulate the head track width, which causes a problem of high cost and low yield.

The magnetic head shown in FIG. 6 avoids the problem of the pseudo gap by making the interface between the ferrite back core 1 and the magnetic alloy film 2 wavy, but has the drawback of increasing the step of wavy processing of ferrite. Therefore, there is a problem that it becomes difficult to process a narrow track.

Further, a magnetic head having a structure as shown in FIG. 7A has been put into practical use. The magnetic head shown in FIG.
A diffusion prevention film 6 made of SiO ₂ , Al ₂ O ₃ or the like is provided at the interface between the ferrite back core 1 and the magnetic alloy film 2 in the simple MIG head shown in FIG. The diffusion prevention film 6 is formed by forming a thin film of SiO ₂ or Al ₂ O ₃ by a thin film forming method such as sputtering. With this configuration,
A non-magnetic layer is intentionally formed at the interface between the ferrite back core 1 and the magnetic alloy film 2, but the layer thickness is up to 0.01 μm.
When the thickness is about m, mutual diffusion at the interface can be prevented, and the pseudo gap can be suppressed to a level that does not pose a problem in practical use.

FIG. 7B shows ferrite and Fe-Ta-N.
Depth profile (F) measured by Auger electron spectroscopy when SiO ₂ (70 Å) was formed as a diffusion prevention film at the interface with the alloy film and heat treatment was performed (500 ° C., 1 hour).
Only the e, N, O, and Si signals are shown). Figure 4 (b)
It can be seen that the diffusion can be prevented in comparison with.

However, the magnetic head having such a structure is
A slight change in stress, adhesive force, or film structure due to the film thickness of the diffusion prevention film 6 or formation conditions causes variations in the pseudo signal (~ 2d).
There is a problem in that stable characteristics cannot be obtained. Further, in the processing step after film formation, there is a problem that the yield decreases due to problems such as chipping and film peeling near the interface between the ferrite core 1 and the magnetic alloy film 2.

In view of the above-mentioned conventional problems, the present invention can prevent mutual diffusion at the interface between the ferrite core and the magnetic alloy film, stably keep the pseudo gap below the practical level, and at low cost. An object of the present invention is to provide a magnetic head having a good yield and a method for manufacturing the magnetic head.

[0012]

According to the present invention, there is provided a magnetic head comprising:
A magnetic alloy film of the MIG head whose average composition is represented by the following formula (1) is used, and a portion having a high nitrogen concentration is provided at an interface between the magnetic alloy film and the ferrite core.

TxMyNz (1) where T is Fe or Co, and M is Nb, Zr, T
at least one metal selected from the group consisting of a, Hf, Cr, W, and Mo, N is nitrogen, and x, y, and z represent atomic percentages, and 65 ≦ x ≦ 94 and 5 ≦ y ≦ 25, respectively. , 0 <z ≦ 20, and x + y + z = 100.

Preferably 0.5 μm from the ferrite surface
The nitrogen concentration of the magnetic alloy film within the range is not less than 2 times and not more than 10 times the nitrogen concentration of the entire magnetic alloy film.

The method of manufacturing the magnetic head of the present invention is
When forming a magnetic alloy film on a ferrite core by reactive sputtering in a mixed gas atmosphere of argon and nitrogen using a magnetic material target, the first step is to set the nitrogen gas partial pressure ratio η in the mixed gas atmosphere to 20%. A magnetic alloy film having an initial film thickness of 0.02 μm or more and 0.1 μm or less is formed by controlling the film thickness to 50% or less, and the second step is to control the nitrogen gas partial pressure ratio to 5% or less to leave the specified film thickness. Is formed. However, assuming that the partial pressure of nitrogen gas is P _N2 and the sputtering pressure is P _TOTAL , the partial pressure ratio η of nitrogen gas is expressed by the following equation (2).

Η = P _N2 / P _TOTAL × 100 [%] (2)

[0017]

In the above structure of the present invention, the nitride alloy film having a high nitrogen concentration is provided in the vicinity of the interface between the magnetic alloy film of the MIG head and the ferrite core, so that the interdiffusion at the interface between the ferrite core and the magnetic alloy film is prevented. It can be suppressed, and the pseudo gap is unlikely to occur even though the interface is parallel to the magnetic gap portion. Further, since a single magnetic alloy film is used only by forming a portion having a high nitrogen concentration in the magnetic alloy film, it is suitable for mass production, and a parallel MIG head in which a pseudo gap does not matter can be stably produced at low cost.

Here, the conditions of x ≦ 94 and y ≧ 5 are the conditions necessary for the magnetic alloy film to exhibit soft magnetism, and x ≧ 94.
The condition of 65 and y ≦ 25 is necessary for the magnetic alloy film to exhibit a sufficiently high saturation magnetic flux density. Further, the condition of z> 0 is a condition necessary for suppressing the pseudo gap, and z ≦ 20.
The condition (1) is necessary to prevent the saturation magnetic flux density from decreasing and to prevent the internal stress of the magnetic alloy film from becoming too large.

[0019]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the magnetic head and the manufacturing method thereof according to the present invention will be described below with reference to FIGS.

FIG. 1 (a) shows a front view of the MIG head of this embodiment, and FIG. 1 (b) shows the interface diffusion state between the ferrite core of the MIG head and the Fe-Ta-N alloy film by Auger electron spectroscopy. The result of analysis by the depth profile (extracting only the signals of Fe, N, and O) is shown.

In FIG. 1A, 1 is a ferrite back core, 2 is a magnetic alloy film, 3 is a magnetic gap made of SiO ₂ or the like, 4 is glass for joining cores, and 5 is a magnetic alloy film having a high nitrogen concentration. . The film thickness of the magnetic alloy film 5 having a high nitrogen concentration is 0.5 μm or less, while the film thickness of the magnetic alloy film 2 is about several μm, and is about 0.04 μm in this embodiment.

As can be seen from FIG. 1B, in this embodiment, mutual diffusion at the interface can be almost prevented without using a diffusion preventive film such as SiO ₂ or Al ₂ O ₃ . That is, of the magnetic alloy film 2 formed on the ferrite back core 1, the magnetic alloy film 5 having a thickness of about 0.5 μm from the ferrite surface.
By adjusting the nitrogen density of the magnetic alloy film 2 to be not less than 2 times and not more than 10 times the average nitrogen concentration of the entire magnetic alloy film 2, a pseudo gap is generated while preventing the formation of a non-magnetic layer having a reduced magnetic permeability at the interface. Can be suppressed. The pseudo signal of the MIG head created with this configuration showed a good characteristic of ˜0.7 dB. Note that FIG. 1B shows a depth profile in the range of 0.2 μm from the surface of the ferrite back core 1.

Next, among the above magnetic alloy films, Fe-Ta-
A method of manufacturing the N alloy film will be described with reference to FIGS. FIG. 2 shows a schematic configuration of a reactive sputtering apparatus for forming a magnetic alloy film, and FIG. 3 shows a control method of Ar and N ₂ gas flow rates during sputtering.

In FIG. 2, the Fe-Ta target 11 is shown.
Is attached to a sputtering electrode 14 installed in a vacuum chamber 13 via an insulating material 12. A DC or AC sputtering power source 15 is connected to the sputtering electrode 14. The ferrite core 16 is arranged at a position facing the sputtering electrode 14, and is attached to a substrate holder 17 having a substrate cooling mechanism using cooling water or the like. A shutter 18 is installed between the sputtering electrode 14 and the substrate holder 17 to prevent a thin film from being formed on the substrate during pre-sputtering. A vacuum exhaust system centering on a vacuum pump 19 is connected to the vacuum chamber 13 via a pressure adjusting valve 20, and further, an Ar gas source 21 and an N ₂ gas source 22 are independently provided with gas flow rate controllers 23 and 24. Connected through.

In the reactive sputtering apparatus prepared as described above, first the vacuum pump 19 evacuates the inside of the vacuum chamber 13 to about 10 ^-7 Torr. Next, A is supplied from the Ar gas source 21 through the gas flow controller 23.
By introducing r gas, the pressure in the vacuum chamber 13 is kept at a sputtering pressure of about 10 ^-2 to 10 ^-3 Torr by the pressure control valve 20. Here, by applying a negative high voltage or high frequency voltage from a DC or AC sputtering power source 15 connected to the sputtering electrode 14,
Plasma is generated near the target 11 to start sputtering. About 10 minutes, after performing the pre-sputtering for removing impurities from the surface of the target 11, to set the sputtering power, N ₂ gas was introduced from the N ₂ gas source 22 through a gas flow controller 24, the pressure The nitrogen gas partial pressure ratio is kept at 20 to 50% by using the adjusting valve 20 together. here,
When the shutter 18 is opened, Fe and Ta jumping out from the target due to the sputtering phenomenon react with N in the discharge gas to form an Fe-Ta-N alloy film on the ferrite core 16.

In the actual film forming process, as shown in FIG. 3, first, the shutter 18 is opened as a first step, and the nitrogen gas partial pressure ratio is 20 to 50% and Fe-Ta having a high nitrogen concentration for diffusion prevention is used.
For the N alloy film, the sputtering time was controlled to 0.02 to 0.
1 μm is formed. Next, in the second step, in order to obtain soft magnetism and high saturation magnetic flux density, the partial pressure ratio of nitrogen gas is kept at 3 to 5%, and the sputtering time is also controlled to carry out sputtering until a prescribed film thickness is obtained.

As described above, the magnetic alloy film used in the MIG head of the present invention can be obtained by a very simple method of controlling the nitrogen concentration during sputtering in two steps.

[0028]

As apparent from the above description, according to the magnetic head of the present invention, by providing a portion having a high nitrogen concentration at the interface with the ferrite core of the magnetic alloy film as a countermeasure against the pseudo gap, It is not necessary to incline or corrugate the interface between the ferrite core and the magnetic alloy film with respect to the magnetic gap, and it is not necessary to form a diffusion prevention film such as SiO ₂ or Al ₂ O _{3 on the} interface. Mutual diffusion at the interface with the alloy film can be prevented, pseudo gap can be suppressed even if the interface is parallel to the magnetic gap part, and a single magnetic alloy film can be formed only by forming a part with high nitrogen concentration in the magnetic alloy film. Therefore, it is suitable for mass production, and the parallel MIG head in which the pseudo gap does not matter can be stably produced at low cost.

Further, the nitrogen concentration of the magnetic alloy film within 0.5 μm from the ferrite surface is twice or more the total nitrogen concentration 1
By setting the ratio to 0 times or less, it is possible to reliably suppress the generation of the pseudo gap while preventing the formation of a non-magnetic layer having a reduced magnetic permeability at the interface.

According to the method of manufacturing a magnetic head of the present invention, the magnetic head can be manufactured by a very simple method in which the nitrogen concentration during sputtering is controlled in two steps. It is possible to produce the magnetic head with good stability.

[Brief description of drawings]

FIG. 1 shows a magnetic head of one embodiment of the present invention, (a)
Is a front view, and (b) is a diagram showing a depth profile of the interface between the ferrite core and the magnetic alloy film by Auger electron spectroscopy.

FIG. 2 is a schematic configuration diagram of a reactive sputtering apparatus used in the method of manufacturing the magnetic head of the example.

FIG. 3 is an explanatory diagram of a control method of Ar and N ₂ gas flow rates during sputtering in the manufacturing method of the example.

FIG. 4 shows a conventional magnetic head, in which (a) is a parallel MI.
FIG. 3B is a front view of the G head, and FIG. 3B is a view showing a depth profile of the interface between the ferrite core and the magnetic alloy film by Auger electron spectroscopy.

FIG. 5 is a front view of another conventional MIG head.

FIG. 6 is a front view of another conventional MIG head.

7A and 7B show still another conventional example, FIG. 7A is a front view of a MIG head, and FIG. 7B is a diagram showing a depth profile of an interface between the ferrite core and a magnetic alloy film by Auger electron spectroscopy.

[Explanation of symbols]

1 Ferrite Back Core 2 Magnetic Alloy Film 3 Magnetic Gap 5 High Nitrogen Concentration Magnetic Alloy Film 11 Target 16 Ferrite Core 21 Ar Gas Source 22 N ₂ Gas Source

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Yasushi Inoue 1006 Kadoma Kadoma, Osaka Prefecture Inside Matsushita Electric Industrial Co., Ltd.

Claims (3)

[Claims] 1. The back core is made of ferrite, and the average composition of the entire film in the vicinity of the magnetic gap is expressed by the following formula: TxMyNz (where T is Fe or Co, M is Nb, Zr, T).
at least one metal selected from the group consisting of a, Hf, Cr, W, and Mo, N is nitrogen, and x, y, and z represent atomic percentages, and 65 ≦ x ≦ 94 and 5 ≦ y ≦ 25, respectively. , 0 <z ≦ 20, and x + y + z = 100. In the magnetic head having the magnetic alloy film shown in (4), a portion having a high nitrogen concentration is provided at the interface of the magnetic alloy film with the ferrite core. 2. The magnetic head according to claim 1, wherein the nitrogen concentration of the magnetic alloy film within 0.5 μm from the surface of the ferrite core is not less than 2 times and not more than 10 times the nitrogen concentration of the entire magnetic alloy film. . 3. A magnetic material target is used for reactive sputtering in a mixed gas atmosphere of argon and nitrogen,
When the magnetic alloy film is formed on the ferrite core, as a first step, the partial pressure ratio of nitrogen gas in the mixed gas atmosphere is controlled to 20% or more and 50% or less and the initial film thickness is 0.02 μm or more and 0.1% or more.
2. A magnetic alloy film having a thickness of 1 .mu.m or less is formed, and in the second step, the partial pressure ratio of nitrogen gas is controlled to be 5% or less to form the remaining magnetic alloy film up to a prescribed film thickness. Magnetic head manufacturing method. (However, nitrogen gas partial pressure ratio: η = P _N2 / P _TOTAL × 10
0 [%] P _N2 : nitrogen gas partial pressure, P _TOTAL : sputtering pressure. )