JPS59170248A - Heat treatment of amorphous alloy - Google Patents

Abstract

PURPOSE:To provide high magnetic permeability to an amorphous alloy and to reduce a change in the magnetic permeability with the lapse of time by subjecting the alloy to secondary heat treatment at a temp. below the Curie temp. and below the crystallization temp. in a rotating magnetic field after primary heat treatment. CONSTITUTION:An amorphous alloy having magnetic anisotropy is subjected to primary heat treatment at a temp. below the crystallization temp. The alloy is then subjected to secondary heat treatment at a temp. below the Curie temp. and below the crystallization temp. in a magnetic field rotating relatively to the alloy. The heat-treated amorphous alloy having reduced anistropic magnetism and improved magnetic permeability is stable to the following heat treatment at a low temp., so it undergoes no change in the characteristics. When this heat treatment method is applied to the manufacture of a magnetic head, a magnetic head having superior characteristics is obtd.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Application of the Invention] The present invention relates to a method of heat treating an amorphous alloy and a method of manufacturing a magnetic head using the same.

[Prior art]

In recent years, magnetic recording technology has made significant progress with the development of high coercive force tapes and high performance magnetic head materials. Conventional magnetic head materials include pe-At-5i and Fe-
Crystalline magnetic materials such as 4Ji-based materials have been used, but the saturation magnetic flux density BS of these materials is less than 10 KG, and Bs is too high for use in magnetic heads for high coercive force tapes.
There is a problem that, since it is a crystal, it has magnetocrystalline anisotropy, and the composition range in which the magnetocrystalline anisotropy is minimal and high magnetic permeability characteristics can be obtained is extremely narrow. Amorphous alloys, which have been developed in recent years, have no crystal magnetic anisotropy because they are amorphous and therefore have high magnetic permeability. However, on the other hand, amorphous alloys have drawbacks as described below.

That is, since the amorphous alloy is a metastable phase, it changes to a stable crystalline phase above the crystallization temperature, and as a result, a significant increase in Hc and a decrease in magnetic permeability occur. It is known that even at temperatures below the crystallization temperature, magnetic permeability gradually decreases over time when heated for a long time.
This is a major problem for the practical application of amorphous alloys. Furthermore, high magnetic permeability can be obtained from amorphous alloys by heat-treating them after fabrication, but this heat treatment must be performed at a temperature above the Curie temperature and below the crystallization temperature of the amorphous alloy. It is known that this is not the case (Patent Publication No. 53-43028). If this heat treatment is performed at a temperature below one Curie temperature, the magnetic permeability cannot be improved and may actually decrease. The heating temperature of an amorphous alloy tends to be approximately proportional to the saturation magnetic flux density, and for an amorphous alloy with a saturation magnetic flux density of about 8 KG or more, the heating temperature will exceed the crystallization temperature. Therefore, in such a case, heat treatment at a temperature below one Curie temperature is impossible, and there is a problem in that it is difficult to increase the magnetic permeability by heat treatment.

[Purpose of the invention]

It is an object of the present invention to solve such problems by providing an amorphous alloy with a high saturation magnetic flux density and a Curie temperature higher than the crystallization temperature, a high magnetic permeability characteristic regardless of its shape, and a change in magnetic permeability over time. By providing a heat treatment method that reduces changes and applying this to the manufacturing method of magnetic heads,
An object of the present invention is to provide a method for manufacturing a magnetic head with excellent characteristics.

[Summary of the invention]

In order to achieve the above object, the present invention employs a method in which an amorphous alloy is subjected to a first heat treatment at a temperature below its crystallization temperature, and then a second heat treatment is performed in a rotating magnetic field or a unidirectional magnetic field. The reason why the entire first heat treatment is performed here is to stabilize the amorphous alloy and suppress changes in magnetic permeability over time.The second heat treatment in a rotating magnetic field or in a unidirectional magnetic field stabilizes the magnetic permeability. It is intended to increase.

[Embodiments of the invention]

Next, the heat treatment method of the present invention will be explained in detail using an example.

As mentioned above, amorphous alloys do not have magnetocrystalline anisotropy, but depending on manufacturing conditions, they generally have magnetic anisotropy.For example, thin plate-like amorphous alloys made by the splat cooling method generally has magnetic anisotropy in which the longitudinal direction of the sample is the direction of easy magnetization, and amorphous alloy films fabricated by thin film fabrication techniques such as sputtering are sensitive to the minute magnetic field applied during fabrication. It has a corresponding magnetic field anisotropy.

The magnetic anisotropy of such an amorphous alloy is considered to be induced magnetic anisotropy that occurs because the entire amorphous alloy is manufactured under stress or in a magnetic field.

The direction and magnitude of the induced magnetic anisotropy of an amorphous alloy can be easily changed by heat-treating it in a magnetic field after preparing a sample. For example, Figure 1 shows CO80 fabricated on a glass substrate by high frequency bipolar sputtering method.
It is a BH curve of an amorphous alloy thin film having a composition of MOIL5C08O (atomic %). During the fabrication of the film, sputtering was performed while applying a magnetic field of 1006 in parallel to the substrate surface.

As shown in the figure, the amorphous alloy thin film has typical uniaxial magnetic anisotropy with the direction of easy magnetization being the direction in which the magnetic field is applied during snobbing. The anisotropic magnetic field HK, which indicates the magnitude of magnetic anisotropy of the film, is 50e, the saturation magnetic flux density Bs is 7KG, and the coercive force Hc
is 0.20 e, and the magnetic permeability in the direction of difficult magnetization is 30 KHz
to 30MH2, the magnetic permeability in the direction of easy magnetization is 100, and the film thickness is 1.5 μm. Next, while applying a magnetic field of 500006 in the direction of difficult magnetization of this sample,
In the case of heat treatment for 30 minutes, the direction in which the magnetic field is applied during the heat treatment is the direction of easy magnetization, resulting in almost no change in saturation magnetic flux density, coercive force, anisotropy magnetic field, and magnetic permeability.

That is, by this heat treatment, the direction of magnetic anisotropy can be changed without changing the magnitude.

Magnetic anisotropy? If you want to change it, you need to fully control the heat treatment temperature and time.

As for the applied magnetic field, it will not affect the results much as long as it saturates the sample sufficiently. Figure 2 shows Co52Nbx3Zrs and C
This figure shows the change in the anisotropic magnetic field Hvc depending on the heat treatment time when an amorphous alloy thin film having a composition of 089W5Zr6 (both atomic %) is heat treated at 300C while applying a magnetic field of 500006 in the direction of difficult magnetization of the sample. In the figure, when HK is negative, the direction of easy magnetization is the direction before heat treatment in a magnetic field, and when HK is positive, the direction of easy magnetization is changed to the direction of the applied magnetic field during heat treatment.

The saturation magnetic flux density of CO52Nbt3Zrs is 10 KG, before heat treatment (7) HK is 110 e% CO59WsZ
Saturation magnetic flux density of rs is 12KG, HK before heat treatment is 20
It is 0e. In both cases, HK decreases due to heat treatment, and 1
After 0 to 20 minutes, the direction of easy magnetization changes, and then HK
increases. In general, magnetic films exhibiting uniaxial magnetic anisotropy have a larger permeability in the direction of difficult magnetization than in the direction of easy magnetization, and when Ha is small, the slope of the B-H curve in the direction of difficult magnetization, that is, saturation. It is approximately proportional to the ratio of magnetic flux density B8 and anisotropic magnetic field HK. In the case of a thin plate sample prepared by the splat cooling method, the magnetic permeability in the direction of difficult magnetization is large at high frequencies where domain wall motion is suppressed, and the values have the same relationship as described above. Therefore, as shown in FIG. 3, the magnetic permeability in the direction of difficult magnetization reaches a maximum near where HK is less than 0, and a high magnetic permeability of about 4000 is obtained.

It is also possible to reduce the magnetic anisotropy of an amorphous alloy by heat treatment in a magnetic field by performing heat treatment while rotating the magnetic field and the sample relative to each other.
CO80M o lt produced by high frequency bipolar sputtering method while applying a magnetic field of 0e parallel to the substrate,
An amorphous alloy thin film having a composition of sZ r s, s and C081,5Tjla5 (all atomic %) was
This figure shows the dependence of the magnetic permeability in the direction of difficult magnetization in HK and 5MH2 on the heat treatment temperature when the sample was heat treated for 30 minutes in a magnetic field of 00e while rotating at #500 r-. Saturation magnetic flux density 7KG, Hx5 before heat treatment
Co soM Of 1s Z ras of Qe and saturation magnetic flux density 9KG, C0at of HK150e before heat treatment
In both s T j ta and s, HK decreases and magnetic permeability increases significantly by heat treatment in a rotating magnetic field.

On the other hand, FIG. 5 shows the case where these amorphous alloys were subjected to normal heat treatment without being subjected to a magnetic field. The annealing time was 10 minutes. As shown in the figure, CosoMott, sZ r8 with Q'J TEA degree Tc of 450C and crystallization temperature Tx of 600C
．． 5, the UK decreases and the permeability in the difficult axis direction increases significantly through normal heat treatment, whereas the Tx is 520C and the T
In C0stsT 111L5, where c is higher than Tx, HK and magnetic permeability hardly change by heat treatment, and the magnetic properties deteriorate near the crystallization temperature.

As mentioned above, it is not possible to reduce Hx or improve magnetic permeability by heat treatment for amorphous alloys with large saturation magnetic flux density and Tc higher than Tx. Therefore, heat treatment in a magnetic field is particularly effective for improving magnetic properties. It is valid. The HK of the amorphous alloy thin film after fabrication tends to become narrower as the saturation magnetic flux density increases, and the magnetic permeability tends to decrease accordingly.

This also applies to amorphous alloys produced by the splat cooling method, and amorphous alloys with a high saturation magnetic flux density generally have a low magnetic permeability after production. Therefore, heat treatment in a magnetic field is essential when applied to an amorphous alloy all-magnetic head with a high saturation magnetic flux density.

Next, a case will be described in which an amorphous alloy is subjected to normal heat treatment and then heat treatment in a magnetic field. The aforementioned C089W5 Z r
After fabricating the amorphous alloy thin film by sputtering 3
00U, 350C1400c.

Figure 6 shows the change in magnetic permeability in the hard axis direction for HK and 5MH2 with heat treatment time when heat treated at 450C for 10 minutes each and then heat treated at 350tll' while applying a magnetic field of 50000e in the hard magnetization direction. FIG. 6 also shows the case where the above-mentioned thin Co5zNb13Zrs amorphous alloy thin film was prepared by sputtering, heat-treated at 4700° C. for 10 minutes, and then heat-treated in the same manner. In the figure, Hx and p are the same as in FIG. As shown in the figure, in any amorphous alloy thin film, if the heat treatment temperature before heat treatment in a magnetic field is high, the HK hardly changes, and it takes a long time for the easy magnetization direction to change.

At the same time, changes in magnetic permeability are also occurring. The above results are the same even when heat treatment in a rotating magnetic field is performed after normal heat treatment. This phenomenon is thought to occur because a certain factor that helps change the induced magnetic anisotropy of the amorphous alloy gradually disappears due to heat treatment. For example, a large number of defects generated in the sample during fabrication This can be explained by a model in which the diffusion movement of atoms is promoted to help change the induced magnetic anisotropy, and heat treatment eliminates these defects, making it difficult for the induced magnetic anisotropy to change. The amorphous alloy, whose Hx is reduced and magnetic permeability is greatly improved through such heat treatment, does not change its characteristics even after subsequent low-temperature heat treatment, and is therefore extremely stable with little change over time, and has high saturation magnetic flux. An amorphous alloy with high density and high magnetic permeability properties can be obtained.

The degree of stabilization of the aging of the amorphous alloy described above is
It is determined by the cumulative temperature and time that an amorphous alloy experiences after its manufacture.Therefore, even if the amorphous alloy is subjected to heat treatment in a magnetic field at a relatively high temperature for a long period of time without undergoing normal heat treatment, it will not change over time. Reduction is possible. However, when heat treatment in a magnetic field is performed without ordinary heat treatment, there are problems as described below. In other words, when an amorphous alloy is produced and then heat treated while applying a magnetic field in the direction of difficulty in magnetization, the HK changes in a short time even with heat treatment at a relatively low temperature of 30 (I'), as shown in Figure 2. This makes it difficult to control HK.

When the heat treatment temperature is lowered to facilitate control of HK, the effect of reducing changes over time is small. Furthermore, if heat treatment is performed in a rotating magnetic field at a relatively high temperature without ordinary heat treatment, for example, in the case of heat treatment at 400C or higher as shown in Fig. 4, the relationship between the easy magnetization direction after heat treatment and the easy magnetization direction before heat treatment becomes unstable. As a result, the direction of easy magnetization cannot be controlled.

That is, in this state, the direction of easy magnetization is determined by the slight strain and magnetostriction remaining in the sample. Since the value of magnetic permeability is quite different between the direction of easy magnetization and the direction of difficult magnetization, the inability to control the direction of easy magnetization is extremely problematic in practical terms. This can be prevented by lowering the heat treatment temperature, but as a result, the effect of reducing changes over time becomes less effective.

As described above, performing a first heat treatment without applying a magnetic field after producing an amorphous alloy, and then performing a second heat treatment in which a magnetic field is applied is a good method for controlling Htc. In principle, the first and second heat treatment temperatures can be as low as room temperature, but in practice it is necessary to set the temperature to 150C or higher in order to prevent Hz control from taking an extremely long time. The upper limit of the heat treatment temperature is the crystallization temperature of the amorphous alloy. Furthermore, since making the temperature of the second heat treatment much higher than the first heat treatment temperature makes it difficult to control HK, the temperature of the second heat treatment is set to the temperature of the first heat treatment plus 5 (I'). It is desirable to make it lower.

Although the heat treatment method of the present invention is effective regardless of the method and shape of the amorphous alloy, it is particularly effective for amorphous alloy thin films produced by thin film production techniques such as sputtering. That is, although a thin plate-like amorphous alloy produced by a splat cooling method has induced magnetic anisotropy, the direction and magnitude thereof are not necessarily constant and are unstable. On the other hand, amorphous alloy thin films fabricated by thin film fabrication techniques such as sputtering exhibit stable magnetic anisotropy in magnitude and direction each time they are fabricated. However, since the magnetic anisotropy of amorphous alloys fabricated using this method is extremely susceptible to the influence of the magnetic field that was present during fabrication, it was fabricated while applying a magnetic field sufficient to saturate the amorphous alloy. This makes it possible to stably obtain samples with uniform magnetic anisotropy in magnitude and direction. Therefore, when such an amorphous alloy thin film is heat-treated by the method of the present invention, HK can be easily controlled.

Although the heat treatment method of the present invention is effective regardless of the composition of the amorphous material, the saturation magnetic flux density is large and the Curie temperature is higher than the crystallization temperature of the amorphous crystal, which cannot be reduced in HK or improved in magnetic permeability by ordinary heat treatment. Particularly effective for high quality alloys. Amorphous alloys are generally Fe, Co.

It consists of a magnetic transition metal element such as Ni and an amorphous element, and B is the amorphous element.

Metalloid elements such as c, At, s+, p, oe and T
There are transition metal elements such as i, y, Zr, Nb, Hf, Ta, W, and rare earth elements. Since metalloid elements generally have a fast diffusion rate in amorphous alloys, amorphous alloys containing a large amount of metalloid elements have the disadvantage that induced magnetic anisotropy changes quickly and changes over time. Therefore, in order to obtain an amorphous alloy with little change over time, it is desirable to contain no metalloid elements at all, or to contain them in an amount of 10 atomic percent or less.

The method of heat treating an amorphous alloy of the present invention can be used as is as part of the manufacturing process of a magnetic head. The manufacturing process of a magnetic head often includes a step of applying heat, and this step can be used as the first heat treatment of the present invention, followed by heat treatment in a magnetic field as the second heat treatment. FIG. 7 shows an example in which the heat treatment method of the present invention is applied to the manufacture of a magnetic head. Mirror polishing is performed in Figure 7 (a),
A substrate 1 whose surface was cleaned was prepared. In this example, Photoceram (trade name of Corning, Inc., USA) was used as the substrate material. Next, in Fig. 7(b), 10
The amorphous alloy thin film 2 was deposited on the substrate by high frequency bipolar sputtering while applying a magnetic field of 0e. In this example, C089W5Zf6 was used as the amorphous alloy thin film. The film thickness was 20 μm. Next, in FIG. 7(C), a protective plate 3 of photoceram was bonded using P, b type glass. During this bonding, the sample was heated at 400C for 10 minutes, which was the first heat treatment in the present invention. As the second heat treatment in the present invention, 13,000 yen perpendicular to the substrate surface
Heat treatment was performed at 350 t:'' for 1 hour without applying a magnetic field of 0.06 mm to impart a small magnetic anisotropy with the perpendicular direction to the film surface of the amorphous thin film as the direction of easy magnetization.

Next, cut along the broken line in FIG. 7(C), and mirror-polish the gap abutting surfaces 4, 4' in FIG. 7(d) to form a bonding groove 5.5' and a winding window groove 6. was processed, and a gap material was applied to the gap abutting surfaces 4.4'. Next, the head core halves 7 and 7' are integrated via a gap material as shown in FIG. 9 was produced. The magnetic head manufactured by the above steps had a reproduction output approximately 4 dB higher than that of the magnetic head shown in FIG. 7(C) which was not subjected to heat treatment in a magnetic field.

In addition to the above manufacturing method, the heat treatment method of the present invention can be applied in various ways. For example, C05z as an amorphous alloy thin film
Using Nb13Zrs, bonding of the protective material was carried out at 470C for 10 minutes as shown in Fig. 7(C), and in Fig. 7(e), using PB glass as the bonding adhesive, a magnetic field was applied perpendicular to the substrate surface. However, there is also a method in which a second heat treatment is performed at 400 C for 1 hour, and this second heat treatment and the step of joining and integrating the magnetic held core half-dead are performed simultaneously.

Next, an example in which the heat treatment method of the present invention is applied to the manufacture of a thin film magnetic head is shown in the sectional view of a thin film magnetic head in FIG. In FIG. 8(a), a gap material 11 of 5102 is deposited on a high magnetic permeability M n -7, n ferrite substrate 10,
Further, an At wiring 12 was formed, and then a polyimide adhesive 13 was applied over the At wiring and cured by heating. Then the 8th
In Figure (b), while applying a magnetic field of 1 ooe in the direction of the arrow, a film thickness of 2 μm was formed by high frequency bipolar sputtering method.
An amorphous alloy thin film 14 of C05zNb13Zrs was deposited.

Next, in FIG. 8(C), this amorphous alloy thin film was etched to regulate the track width, and then a photoceram protective plate 15 was bonded with glass 16. In this step, heat treatment was performed at 400C for 10 minutes. After that, heat treatment was performed at 350C for 1 hour while applying a magnetic field of 500002 in the track width direction of the thin film magnetic head to give the amorphous alloy thin film a small magnetic anisotropy with the track width direction of the thin film magnetic head as the direction of easy magnetization. did. The thus manufactured thin film magnetic head had a reproduction output approximately 3 dB higher than that of a thin film magnetic head that was not subjected to heat treatment in a magnetic field.

〔Effect of the invention〕

As described above, according to the heat treatment method of the present invention, 8K
It is possible to obtain an amorphous alloy that has a high saturation magnetic flux density of G or more and a high magnetic permeability, and also has a small change in permeability over time, and it is possible to control the magnitude and direction of the magnetic anisotropy of the amorphous alloy. It becomes easier. When the heat treatment method of the present invention is applied to a method for manufacturing a magnetic head, a magnetic head with high performance and no change in performance over time can be manufactured with a high yield.

[Brief explanation of the drawing]

Figure 1 is an example of the B-H curve of an amorphous alloy thin film, and Figures 2 and 3 are H curves when the amorphous alloy thin film is heat-treated in a magnetic field.
Changes in K and magnetic permeability, Figure 4 shows changes in Hz and magnetic permeability when an amorphous alloy thin film is heat treated in a rotating magnetic field, Figure 5
The figure shows changes in HK and magnetic permeability when an amorphous alloy thin film is subjected to normal heat treatment. Figure 6 shows changes in HK and magnetic permeability when an amorphous alloy thin film is heat treated in a magnetic field after normal heat treatment. Figure 7 (a) to (e) are perspective views showing the steps of the method of manufacturing a magnetic head of the present invention, and FIGS. 8(a) to (C) are sectional views showing the steps of the method of manufacturing the magnetic head of the present invention, respectively. show. 1...Substrate, 2,13...Amorphous alloy thin film, 3,1
5... Protective plate, 4, 4'... Gap butting surface, 5°5'... Joining groove, 6... Winding window groove, 7,
7'...Magnetic rad core half off, 8...Joining adhesive, 9...Magnetic rad core, 10...M n -Z
n ferrite substrate, 11... gap material, 12...
At wiring, 13...poly 1st ward Y 2 mouth 2θ + so 3 z se1 seiri ginkan (h) Teheka way Buddha ('C) 5th Figure 9! : Treated hot water (C) 1-Otsu (Kenyuki Kankari) Rin Kao (h) Fig. 7 (Ku) (Shi) (C
)(Be) Fragment & Diagram (Q) Inside the Hitachi, Ltd. Central Research Laboratory, 1-280 Higashi-Koigakubo, Kokubunji City 0 Inventor: Takeo Yamashita Inside the Hitachi, Ltd. Central Research Laboratory, 1-280 Higashi-Koigakubo, Kokubunji City Inventor: Shiiki- Inside the Central Research Laboratory, Hitachi, Ltd., 1-280 Higashi-Koigakubo, Kokubunji City (η) Inventor: Hori Saito Inside the Central Research Laboratory, Hitachi, Ltd., 1-280 Higashi-Koigakubo, Kokubunji City

Claims (1)

[Claims] 1. After the first heat treatment of an amorphous alloy having magnetic anisotropy at a temperature below its crystallization temperature, in a magnetic field rotating relative to the amorphous alloy, A method for heat treatment of an amorphous alloy, characterized in that a second heat treatment is performed at a temperature below one Curie temperature and below a crystallization temperature. 2. After the first heat treatment of an amorphous alloy having magnetic anisotropy at a temperature below its crystallization temperature, the amorphous alloy is heated at a temperature below one Curie temperature in a magnetic field applied in the direction of difficulty in magnetization of the amorphous alloy. Moreover, the method for heat treatment of an amorphous alloy is characterized in that the second heat treatment is performed at a temperature below the crystallization temperature. 3. In the method for heat treatment of an amorphous alloy according to claim 1 or 2, the temperature in the first and second heat treatments is equal to or higher than i150C, and the heat treatment is performed at a temperature of 1 in the second heat treatment. A heat treatment method for an amorphous alloy characterized in that the temperature is equal to or lower than the temperature of 50C plus 50C. 4. In the method for heat treatment of an amorphous alloy according to claim 1, 2 or 3, the amorphous alloy is produced by a thin film forming technique such as a sputtering method or a vapor deposition method, and A method for heat treatment of an amorphous alloy, characterized in that the preparation of the amorphous alloy is carried out in a magnetic field. 5. In the method for heat treatment of an amorphous alloy according to claim 1, 2, 3, or 4, the amorphous alloy contains 90 atomic % or more of a metal element and 10 atomic % or less of a metal element. A method for heat treatment of an amorphous alloy characterized by being composed of metalloid elements.