JPH0571163B2 - - Google Patents

Description

Detailed Description of the Invention (Industrial Application Field) The present invention relates to a method for heat treatment of an amorphous soft magnetic film having two or more layers, and in particular to a method for heat treatment of an amorphous soft magnetic film having two or more layers, and in particular for obtaining a high magnetic permeability in a wide frequency range and applying it to a magnetic core of a thin film magnetic head. The present invention relates to a heat treatment method for an amorphous soft magnetic film suitable for various magnetic application parts such as.

(Prior Art) Metals usually exist in a solid state with a crystal structure in which the atomic arrangement is regular. Alternatively, by sputtering a certain type of target material with ions and rapidly cooling and depositing the scattered atoms on a substrate, an amorphous soft magnetic material with an atomic arrangement similar to that in the liquid state can be created even in the solid state. It is well known that the following can be obtained.

The amorphous soft magnetic material obtained in this way is
Since the atomic arrangement does not have long-range regularity like crystalline materials and is arranged randomly, it does not inherently have magnetocrystalline anisotropy like crystalline materials.

However, magnetic anisotropy is often induced in the amorphous soft magnetic material for some reason during its manufacture. However, the induced magnetic anisotropy generated in this way is non-uniform in its distribution in size and direction, and the magnetic properties of the material immediately after manufacture are generally not very good, and moreover, it is thermally unstable. be. In addition, when creating an amorphous state, various strains occur due to the manufacturing method, and this remains inside the material, which also impairs magnetic properties and makes it thermally unstable. be. Particularly when the magnetic pole material is molded with glass, as in the case of a magnetic head, if heat treatment is applied after molding, new stress will be generated at the interface with the glass even if the internal strain has been removed. It may even worsen the characteristics.

In order to remove these induced magnetic anisotropy and internal strain during the production of amorphous soft magnetic materials, conventional heat treatment methods are used, for example, in a non-oxidizing atmosphere at a temperature below the Curie temperature and the crystallization temperature. The method of heat treatment in a rotating magnetic field is an effective method and can improve the magnetic permeability in the direct current and low frequency regions.

(Problems to be Solved by the Invention) However, on the other hand, when the induced magnetic anisotropy is removed and the magnetic anisotropy becomes smaller, the magnetic domain structure becomes unstable and coarse, and domain walls tend to move. A problem arises in that the magnetic permeability in the high frequency region (1 MHz or higher) decreases.

In order to improve magnetic permeability in the high frequency region,
As the magnetization process, it is necessary to use magnetization rotation, which has a faster switching speed than domain wall movement. To do this, it is necessary to impart an appropriate amount of uniaxial magnetic anisotropy to the magnetic material and drive it in the difficult axis direction. There is a need.

Furthermore, it is necessary to remove the strain remaining inside the magnetic material before it is covered with a different material such as glass, so that no strain remains inside the magnetic material.

An object of the present invention was made based on the above-mentioned circumstances, and it is an object of the present invention to provide a heat treatment method that improves the high frequency characteristics of an amorphous soft magnetic material. In other words,
In order to improve the properties of amorphous soft magnetic materials used in the high frequency region, it is necessary to remove the induced magnetic anisotropy and internal strain induced during manufacturing, and to adjust the properties of the amorphous soft magnetic material in the desired direction and size according to the purpose. It is necessary to impart uniaxial magnetic anisotropy.

(Means for Solving the Problems) The above object of the present invention is to attach at least two or more layers of an amorphous soft magnetic film, an oxide, a conductive metal film, etc. on a substrate made of an oxide, etc., and process it. In the magnetic application element to be formed, each time the amorphous soft magnetic film is deposited, the non-crystalline soft magnetic film is exposed to a static magnetic field applied in a direction substantially perpendicular to the direction in which high high frequency magnetic permeability is desired to be obtained. After the heat treatment is performed at a temperature lower than the crystallization temperature and the Curie temperature of the crystalline soft magnetic material, and after all the layers of the amorphous soft magnetic film have been deposited, subsequent to the heat treatment, a temperature equal to or lower than the heat treatment temperature is applied. At a temperature lower than that, a final heat treatment is performed in a static magnetic field applied in the main direction in which the amorphous soft magnetic film is desired to finally obtain high high frequency magnetic permeability. This is achieved by a heat treatment method for an amorphous soft magnetic film characterized by controlling the magnitude of uniaxial magnetic anisotropy of a magnetic material.

The amorphous soft magnetic film heat-treated as described above has almost no internal strain, and the uniaxial anisotropy is controlled to an appropriate size according to the purpose, so it can be used in a wide frequency range. High magnetic permeability can be obtained over the entire range, making it suitable for magnetic cores of thin-film magnetic heads.

In addition, in this method, each time an amorphous soft magnetic film is deposited, heat treatment is performed in a static magnetic field to remove strain and impart large uniaxially induced magnetic anisotropy. Another advantage is that the uniaxial magnetic anisotropy is not disturbed even by weak stray magnetic fields or heat received during the process, and stable characteristics can be obtained.

(Example) The present invention will be described below with reference to an example in which the present invention is applied to the production of a thin film magnetic head.

FIGS. 1a and 1b are schematic diagrams showing the shape of the manufactured thin film magnetic head. Coil conductor 4 in the diagram
By applying a current to the magnetic core 7, the magnetic flux flows in the direction shown by the arrow, and the magnetic flux flows from the magnetic gap part 6 to the magnetic core 7.
The magnetic flux leaking out of the magnetic recording medium can be recorded on the magnetic recording medium, or conversely, the magnetic flux leaking from the magnetic recording medium can be transferred to the magnetic gap part 6.
The structure is such that the magnetic flux is guided further into the magnetic core, flows in the direction of the arrow, and induces an induced voltage in the interlinking coils, thereby making it possible to reproduce the recorded signal. Therefore, in this thin film magnetic head, it is necessary to increase the magnetic permeability in the direction of the arrow shown in the figure (ie, mainly in the Y direction) over a wide frequency range.

Further, in this head, the magnetic core 7 is formed of two layers of amorphous soft magnetic films. That is,
A lower magnetic pole film 2 that is in contact with the substrate 1 material, and an upper magnetic pole film 5 that is shaped so as to sandwich the lower magnetic pole film 2 and the coil.
It consists of two layers of amorphous soft magnetic films.

The present invention will be described below in accordance with the manufacturing procedure of this thin film magnetic head. First, an amorphous soft magnetic film (saturation magnetic flux density Bs =
10.5KG, saturation magnetostriction λ _s ≒+3×10 ^-7 , crystallization temperature
Tx=480°C) was formed on the entire surface.

Next, a uniform magnetic field of 1Kθe was applied to this sample in a direction approximately perpendicular to the direction in which high high-frequency magnetic permeability was desired to be obtained, that is, in the direction that would become the X direction in Figure 1 when the head pattern was later formed. ,
and 30 at 350℃ in a vacuum of 10 ^-3 to 10 ^-5 Torr.
A first heat treatment was applied for 1 minute and then cooled to room temperature. The BH curves of the magnetic film before and after this heat treatment are shown in A and B of FIG. 2, respectively. Due to this heat treatment, the unclear induced magnetic anisotropy that had occurred before the heat treatment as shown in A changes to a BH curve that shows clear uniaxial magnetic anisotropy with the easy axis in the X direction as shown in B. There is.
At this stage, anisotropy is imparted in a direction (X direction) substantially perpendicular to the direction in which high magnetic permeability is desired to be obtained, and the magnitude of the anisotropic magnetic field is 10.0θe. At the same time, it was also found that the convex warpage of the substrate that occurred during film attachment almost disappeared after the heat treatment, and the compressive stress that had occurred in the film was removed.

After this first heat treatment, a SiO ₂ film as an insulating material and a Cu film as a coil conductor are deposited between the upper magnetic pole and the lower magnetic pole by sputtering.
The process of patterning these is repeated to form a coil pattern interlinking with the magnetic core, a magnetic gap, a rear contact portion of the magnetic core, etc. These patternings were performed by forming a photodist pattern using photolithography and dry etching using an ion beam.

After forming the magnetic gap and the rear contact part of the magnetic core, by sputtering method,
An amorphous soft magnetic film having the same composition as the bottom pole and having a thickness of 10 μm was deposited as the top pole. At this point
The BH curve no longer shows clear uniaxial anisotropy as shown in FIG. 2C. However, this property is different from B and A.
The characteristics are close to those obtained by overlapping the BH characteristics, indicating that the upper magnetic pole film having the same characteristics as A was attached while maintaining the characteristics of the lower magnetic pole after heat treatment. After this, in a uniform magnetic field of 1 kθe applied in the X direction as in the first heat treatment, and
A second heat treatment was performed at 350° C. for 30 minutes in a vacuum of 10 ⁻³ to 10 ⁻⁵ Torr and cooled to room temperature. at this time
The BH characteristic became a BH curve completely similar to B as shown in Fig. 2D. At the same time, the convex warpage of the substrate that occurred when the upper magnetic pole film was attached almost disappeared after the heat treatment, and both the compressive stress that had occurred in the upper magnetic pole film and the tensile stress that had occurred in the lower magnetic pole film were removed. . After measuring the magnetic properties and warpage, it was then tested at 300℃ in a uniform magnetic field of 1kθe applied in the Y direction and in a vacuum of 10 ^-3 to ^{10 -5} Torr.
A third heat treatment was performed for 200 minutes and cooled to room temperature.
The BH characteristics of the upper and lower magnetic poles after the third heat treatment are shown in FIG. 2E. Due to the first and second heat treatments, an anisotropic magnetic field of 10.0 was applied in the X direction to both the upper and lower magnetic pole films.
The uniaxial magnetic anisotropy of [θe] is determined by the static magnetic field in the Y direction applied during the third heat treatment and the temperature conditions of 300°C and 200 minutes to maintain the easy axis of both the upper and lower magnetic pole films in the X direction. However, only the size decreased, changing to a film exhibiting uniaxial magnetic anisotropy with an anisotropic magnetic field of approximately 3 [θe].

The magnetic head is then completed by patterning the upper magnetic pole, adhering a protective layer and bonding the protective plate, and then finishing it into a predetermined shape by machining.

As described above, by using the heat treatment method of the present invention, strain in the amorphous soft magnetic film is removed each time each film is deposited, so there is no deterioration of magnetic properties due to strain, and large and clear uniaxial magnetic Since the process can proceed with anisotropy imparted, the magnetic properties are unlikely to be disturbed during the process, making it possible to align the uniaxial magnetic anisotropy of each layer to the same magnitude, ultimately controlling the magnetic anisotropy reliably. can do.

The magnitude of the uniaxial magnetic anisotropy depends on the temperature of the heat treatment performed each time each film is deposited, such as the first heat treatment, but can generally be controlled by the temperature and time of the final heat treatment.

The heat treatment temperature performed each time each film is attached is 350℃
The relationship between the final heat treatment temperature, time and final uniaxial magnetic anisotropy in the case of Co91.8Zr2.3Nb5.9 (at
%) FIG. 3 shows the case of an amorphous soft magnetic film. Similar relationships can be obtained for CoZrNb amorphous soft magnetic films with other compositions and amorphous soft magnetic films made of other alloying elements, and can be determined by selecting the heat treatment temperature and time according to the material. directional magnetic field
Hk can be controlled.

In addition, the uniaxial anisotropy magnetic field Hk of the magnetic core material is
It is better to make the domain wall as small as possible without making it unstable, and this depends on the core size, but it is about 2~
It is about 6θe. Therefore, from the measurement results in Figure 3,
The final heat treatment at 300°C takes 45 to 300 minutes to obtain the desired uniaxial anisotropy field.

Further, in the above embodiment, after the second heat treatment, the third heat treatment was performed after cooling to room temperature, but the actual treatment may be performed continuously, and at the same temperature.
The same effect can be obtained simply by changing the angle of the applied static magnetic field. Further, although the heat treatment was performed in a vacuum, it may be performed in a non-oxidizing atmosphere.

Furthermore, in this example, the hard axis direction of the magnetic film and the magnetic path direction, which is the direction in which high frequency permeability is desired, are almost parallel, but depending on the structure of the magnetic head, this may not always be possible. In this case, the difficult axis direction and the direction in which high frequency permeability is desired may have a certain inclination. As an example of this, FIG. 4 shows an example of a magnetic head in which the heads are arranged in two adjacent channels and the magnetic paths are non-parallel. In this case, heat treatment should be performed so that the direction (Y direction) that is as parallel as possible to the magnetic path direction of the two channels and has the same inclination to the magnetic path direction of the head of both channels becomes the difficult axis. Just give it.

(Effects of the Invention) As described above, by using the heat treatment method of the present invention, strain in the amorphous soft magnetic film is removed each time each film is deposited, so there is no deterioration of magnetic properties due to strain, and Since the process can proceed with a large and clear uniaxial magnetic anisotropy, the magnetic properties are less likely to be disturbed during the process, and the uniaxial magnetic anisotropy of each layer can be made uniform in size, resulting in anisotropic dispersion. In the end, magnetic anisotropy can be controlled reliably. Furthermore, by selecting the temperature and time of the final heat treatment, it is possible to control the anisotropic magnetic field to an appropriate magnitude depending on the purpose, and the controllability and reproducibility are good.

[Brief explanation of drawings]

FIG. 1 is a diagram illustrating how the present invention is applied to the magnetic core of a thin-film magnetic head. FIG. 1a is a plan view, FIG. 1b is a vertical sectional view, and FIG. Figure 3 is a diagram showing changes in magnetic properties when a magnetic core is heat treated according to the present invention.
Figure 4 shows the relationship between the final heat treatment temperature and time of Co91.8Zr2.3Nb5.9 (at%) amorphous soft magnetic film and Hk. FIG. DESCRIPTION OF SYMBOLS 1... Substrate, 2... Lower magnetic pole film, 3... Insulator, 4... Coil conductor, 5... Upper magnetic pole film, 6...
...Magnetic gap part, 7...Magnetic core.

Claims (1)

[Scope of Claims] 1. A magnetic application element formed by processing and forming at least two or more layers of amorphous soft magnetic film, oxide, conductive metal film, etc. on a substrate made of oxide, etc. Each time a layer of soft magnetic film is deposited, the crystallization temperature and Curie of the amorphous soft magnetic material are adjusted in a static magnetic field applied in a direction perpendicular to the direction in which the amorphous soft magnetic film ultimately wants to obtain high high frequency magnetic permeability. After all the layers of the amorphous soft magnetic film have been deposited by applying heat treatment at a temperature lower than the above temperature, following the heat treatment, the amorphous soft magnetic film is heated at a temperature equal to or lower than the heat treatment temperature. A final heat treatment is performed in a static magnetic field applied in the main direction in which the film ultimately wants to obtain high high-frequency magnetic permeability, and the magnitude of the uniaxial magnetic anisotropy of the amorphous soft magnetic material is determined by the temperature and time of this final heat treatment. 1. A method for heat treatment of an amorphous soft magnetic film characterized by controlling the magnetic field. 2. Claim 1, characterized in that the static magnetic field applied during heat treatment is larger than the demagnetizing field generated in the amorphous soft magnetic film and is large enough to sufficiently magnetize the amorphous soft magnetic film. The heat treatment method described in . 3. The heat treatment method according to claim 1, characterized in that an amorphous soft magnetic film produced by a sputtering method is used. 4. The heat treatment method according to any one of claims 1 to 3, wherein the magnetic application element is a thin film magnetic head.