JPS60206123A - Vacuum heat-treatment device for soft magnetic thin film - Google Patents

Abstract

PURPOSE:To prevent the shifting of axis of easy magnetization generating before or after heat treatment as well as to improve the reliability for a heat treatment by a method wherein a soft magnetic thin film fixed to the sample stand located in a vacuum chamber, a device with which the soft magnetic thin film is heated, and a magnetic device whereon an oval-shaped rotating magnetic field, on which magnetic field which is more powerful than the direction of axis of easy magnetization of the soft magnetic thin film, are provided. CONSTITUTION:Between the two pairs of electrodes of the conventional device in the case of a tetrapole structure of heat treatment device, the number of turns of the excitation coil 5b' of one magnetic pole is increased than that of the excitation coil 5a of the other magnetic pole, and the magnetic field intensity of the direction 12 is made higher than that of the direction 13 which orthogonally intersects with the former. According to this constitution, the intensity of the rotating magnetic field on a sample stand 2 is continuously changed into oval shape. Accordingly, a sample 1 is arranged in such a manner that the axis of easy magnetization of the soft magnetic film will be turned to the direction where the magnetic field of the maximum intensity will be applied, which is the direction 12 in other words. As above-mentioned, the operation to be performed after the arrangement of the sample 1 is same as the heat treatment device of the conventional type, a vacuum chamber 3 is evacuated using a vacuum evacuating device, heated up to the set temperature while applying the oval-shaped rotating magnetic field, and the above is natural-cooled after it has been maintained at the above-mentioned temperature for the prescribed period.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a heat treatment apparatus for soft magnetic thin films used in magnetic recording thin film heads, particularly perpendicular magnetic recording and reproducing heads.

As is well known, +Co-based amorphous thin films (
Co-X, X is * Zr+ Ti+ TarNb
, W, etc.) have useful properties. These thin films are generally created by sputtering, but in the as-deposited state, the magnetic anisotropy of the thin film is large, and the anisotropic magnetic field Hk is 2.
It will be about 00e. Figure 1 shows C as an example of this type of film.
An o -Z r-Nb thin film is taken and its B-H% curved heel at 50 Hz is plotted as an easy axis of magnetization [Figure (a)] and a hard axis of magnetization [Figure (b)] (hereinafter simply referred to as easy axis).

Both directions of the difficulty axis are shown. When these films are used as a magnetic head, the hard axis direction is generally used, where the two-frequency characteristics are good, that is, the frequency dependence of magnetic permeability is small. However, in the as-formed state, the magnetic permeability in the hard axis direction is low, and this film cannot be used as is as a magnetic head material. Therefore, it is difficult to reduce the magnetic anisotropy and increase the magnetic permeability without impairing the good frequency characteristics in the axial direction.

This is heat-treated in a one-rotation magnetic field parallel to the film surface.

FIG. 2 shows a schematic diagram of a conventional heat treatment apparatus, and FIG. 3 shows a plan view thereof.

A sample 1 placed on a sample stage 2 in a vacuum container 3 that has been evacuated by an evacuation device 7 is rotating in a static magnetic field applied by a fixed iron core 6 and its excitation coil 5. This rotational drive is performed by a motor 9 placed in the atmosphere through a rotation introducer 8 cooled by a water-cooled pipe 10.

In this way, a rotating magnetic field is applied to the sample.

The heat treatment is completed by heating to a set temperature with the heater 4, maintaining that temperature for a predetermined period of time, and then cooling naturally.

B of Co-Zr-Nb thin film at 50 Hz after heat treatment
-H characteristic curve is shown in FIG. The B-H characteristic curve 16 in the hard axis direction shows a sharp rise 9, indicating that the magnetic permeability in this direction has increased. 17 is a B-H% property curve in the easy axis direction.

However, in soft magnetic thin films that have been heat-treated using the conventional method described above, the direction of the easy axis often changes before and after the heat treatment, resulting in a direction different from that before the treatment, which causes a decrease in yield. was.

The inventor focused on solving this problem, and through repeated research, modified the 9-rotation magnetic field to create an iso-directional magnetic field with 9 strengths.
The magnetic field strength is changed so that a stronger magnetic field is always applied in the easy axis direction than in the difficult magnetization direction. It has been found that good results can be obtained by applying an elliptical rotating magnetic field. To explain this in detail, yokes 11 are placed on both sides of the sample 1 on the rotating sample stage 2 in FIG. 3 as shown in FIG. 5.
When placing a111b, the positions of the yokes 11a and 11b change with respect to the lines of magnetic force 14 as shown in FIG. 6(a), so the strength 15 of the magnetic field flowing over the sample 1 changes as shown in FIG.
It changes as shown in b) and becomes an elliptical rotating magnetic field.

Here, the direction in which the maximum magnetic field is applied, that is, Fig. 6 (b
) It was discovered that by arranging the sample 1 so that the axis of easy magnetization faces in the direction of the long axis 12 of the sample 1, it is possible to prevent changes in the direction of magnetic anisotropy before and after heat treatment.

By the way, in addition to the above-mentioned method of rotating the sample in a static magnetic field, the method of applying the rotating magnetic field is to fix the sample 1 in a vacuum container, set the fixed core and the excitation coil to have a multipolar structure, and apply alternating current to the excitation coil. , is known as a method of generating a rotating magnetic field by changing the phase of the potential applied to each exciting coil.

FIG. 7 (front view) and FIG. 8 (plan view) are schematic diagrams of the heat treatment apparatus having a one-stroke structure. The sample 1 and the sample stage 2 are fixed in a vacuum container 3, and after the inside of the vacuum container 3 is evacuated by a vacuum evacuation device 7, they are heated by a heater 4. Then, a single-phase alternating current (RfZJt) is directly applied to the excitation coil 5a, and is passed through a capacitor to the other excitation coil 5b.
When flowing single-phase alternating current with a phase lead of 0 degrees, a rotating magnetic field is applied to the fixed sample 1.

Compared to the above-mentioned method of rotating the sample in a static magnetic field, this method omits the complicated rotating introduction material mechanism (see 8 above), so it is economical, less likely to cause trouble, and the single rotation introduction part is less likely to occur. Since the heating prevention mechanism (10 mentioned above) is also omitted, it has the advantage of being extremely compact. However, two problems still remain: the yoke shown in Figure 5;
llb is required, which has the disadvantage that the area occupied by the sample 1 is limited or that the entire apparatus becomes large.

The present invention aims to solve this problem, and can apply an elliptical rotating magnetic field to a sample without using yokes lla and llb. The object of the present invention is to provide a new heat treatment apparatus for soft magnetic thin films that is both reliable and economical.

The present invention will be explained in detail below using the drawings.

FIG. 9 shows a heat treatment apparatus having a quadrupole structure, which is an embodiment of the present invention. Here, the excitation coil 5 of one magnetic pole 6b of the two pairs of magnetic poles 6a+6b of the device in FIG. 7 and Section 8 is shown.
The number of turns of b' is greater than that of the excitation coil 5a of the other magnetic pole 6a, and the magnetic field strength in direction 12 is increased in direction 1 perpendicular to this.
The magnetic field strength should be greater than 3. With this configuration,
The strength of the rotating magnetic field on the sample stage 2 changes continuously in an elliptical shape as shown in FIG.

Therefore, the direction in which this maximum strength magnetic field is applied.

That is, the sample 1 is arranged so that the axis of easy magnetization of the soft magnetic film faces in the direction 12 in FIGS. 9 and 1θ.

The operations after placing the sample 1 in this way are the same as in conventional heat treatment equipment; the vacuum chamber 3 is evacuated using a vacuum evacuation device;
It is heated to a set temperature while applying an elliptical rotating magnetic field, held at that temperature for a predetermined period of time, and then allowed to cool naturally.

The direction of magnetic anisotropy of the soft magnetic thin film subjected to the above heat treatment was the same as the direction of magnetic anisotropy before heat treatment. In addition to changing the number of turns of the excitation coil in each pole pair, an elliptical rotating magnetic field can also be created by changing the effective AC current flowing through the excitation coil and the phase of the AC flowing in each magnetic pole pair. It is known that a similar effect can be obtained when heat treatment is performed by generating an elliptical rotating magnetic field. Reproducibility was also good.

However, the "elliptical shape" as used in the present invention is a strict ellipse.Although the above embodiment describes an apparatus having a quadrupole structure, one rotation magnetic field is possible depending on the number of poles other than quadrupole. The invention is not limited to the number of magnetic poles.

For example, when using three-phase alternating current, a device with a six-pole structure provides a rotating magnetic field most easily.

The present invention has been described above, and according to the apparatus of the present invention, movement of the axis of easy magnetization before and after heat treatment can be prevented, and reliability with respect to heat treatment can be improved. Furthermore, by making the rotation introduction mechanism unstable, maintenance of the heat treatment equipment can be simplified.

Moreover, the device itself can be made extremely compact.

The present invention greatly contributes to improving the characteristics and economic efficiency of magnetic recording thin film heads, particularly perpendicular magnetic recording heads, and can be said to be an industrially useful invention.

[Brief explanation of the drawing]

Figure 1 shows the B-)L characteristic curves in the easy axis direction (a) and hard axis direction (b) of the Go-Zr-NbN film at 50 Hz, and Figure 4 shows the B-)L characteristic curves of the Go-Zr-NbN film at 50 Hz after heat treatment.
-BH characteristic curve of Zr-Nb thin film. FIGS. 2, 3, 7, and 8 are schematic diagrams of conventional heat treatment equipment, and FIGS. 5 and 6 are diagrams showing a conventional method of applying an elliptical rotating magnetic field. 9 and 10 show examples of the present invention. 1...sample, 2...sample stand, 3...vacuum container. 4...Heater, 5...Exciting coil, 6...Fixed core yoke. 7... Vacuum exhaust device, 8... Rotation introduction mechanism. 9...Motor, 10...Water cooling pipe, 11...Yoke. 12... Major axis direction, 13... Minor axis direction, 14...
Mark/J [+magnetic field. 15... Strength of the magnetic field flowing over the sample 16... Difficult + I Tsumugi, 17... Easy axis. Patent applicant Nichiden Anelva Co., Ltd. FIG, 2 Hi 1 (j, 4 Hi IG, 5 (a) FIG, 6 FIG, B FIG, 9

Claims (1)

[Claims] A soft magnetic thin film fixed on a sample stage in a vacuum chamber. A soft magnetic thin film characterized by comprising: a device for heating the soft magnetic thin film; and a magnetic device for applying an elliptical rotating magnetic field such that a magnetic field stronger than the axis of easy magnetization of the soft magnetic thin film is applied. Vacuum heat treatment equipment.