JPS62252122A - Magnetic thin film - Google Patents

Abstract

PURPOSE:To remarkably reduce cracks and crazes in a magnetic substrate by properly managing H density of a magnetic thin film depositing atmosphere. CONSTITUTION:H2 partial pressure in a sputtering atmosphere is set at 10<-10> Torr or lower to reduce H atoms introduced into a magnetic thin film 1. After a Sendust film 1 is formed on a ferrite substrate 2, its temperature is returned to room temperature. Then, a compression stress to make it convex on the side of the film 1 is generated. When it is heated up to 600 deg.C, the stress is increased. When held at 600 deg.C, H atoms are less in the Sendust film. Thus, a dislocation of the Sendust film hardly occurs, and the stress is scarcely alleviated or, even if the stress is moderated, its value is small. When returned to room temperature, since the stress moderation in the case where it is held at 600 deg.C is small, the substrate 2 substantially becomes of a flat state to be returned to the original state.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a magnetic thin film, and particularly to a magnetic thin film suitable for application to a magnetic thin film formed on the recording medium sliding surface side of a magnetic head. .

[Prior Art] As the density of magnetic recording increases, the magnetic recording medium (hereinafter referred to as magnetic tape) used also needs to be of a high coercive force (Hc) type.

For example, in magnetic heads for VTRs, as the recording signal density increases, ferrite, which is a magnetic oxide, does not have enough saturation magnetic flux density to handle metal tapes, which are high Hc tapes. It is necessary to form a magnetic core using a composite magnetic material with a magnetic metal material having a magnetic flux density.

[Problem that the invention attempts to solve] By the way! In a magnetic core made of a composite magnetic material of a monomorphic oxide and a magnetic metal material, for example, the linear expansion coefficient of ferrite is 100-120 XIG/'0,
Sendust (Fe-Al2-3 i) is 150-170
Because it is XIO/''C, during high-temperature processing such as glass welding, stress caused by the difference in thermal expansion causes cracking, peeling, or cracks in the ferrite.

In particular, when a sendust thin film is formed by sputtering or the like on a half of a ferrite core in order to combine a magnetic oxide and a magnetic metal material, cracks in the ferrite core occur due to thermal stress.

The process by which cracks, cracks, etc. occur will be explained based on FIG.

The example shown in FIG. 2 shows a case where a large number of H atoms exist in a magnetic thin film such as sendust.

FIG. 2(a) shows the warped state of the ferrite substrate 2 when the sendust film 1 is formed on the ferrite substrate 2 by sputtering or the like and then returned to room temperature, and compressive stress is generated that makes the sendust 1 side a concave surface. In addition, Fig. 2 (b) shows the sample shown in (a) at 600
This is because the coefficient of linear expansion of Sendust film 1 is larger than that of ferrite when heated to c.

The convex surface on the sendust film 1 side becomes larger, and the compressive stress further increases.

Moreover, FIG. 2(C) shows the case where the above-mentioned sample is held at 600°C, and since the stress in the sendust film 1 is relaxed due to dislocation, the ferrite substrate 2 and the sendust film B'
The convex surface of J l has been eliminated and it has become flat, and the stress has been removed.

On the other hand, FIG. 2(d) shows the case where the above-mentioned sample is returned to room temperature from 600°C. In this case, stress is generated due to the difference in f8 expansion, resulting in a concave surface as a whole, and the stress on the ferrite substrate 2 is tensile. It becomes stress.

Then, the value of this tensile stress is 4X 10' dyn/
If it exceeds cm, cracks or cracks will occur in the ferrite substrate 2.
Sendust n1 will come off.

In addition, in the above explanation, it was explained that processes (b) and (c) proceed as separate processes, but in reality, (b) and (c)
The processes proceed simultaneously.

[Means for Solving the Problems 1] In the present invention, in order to solve the above-mentioned problems, the atmosphere when forming the magnetic S film by the thin film deposition method is set to H2.
The film was formed at a partial pressure of 10 7 all or less.

[Function] When the above-described structure is used, the number of H atoms in the magnetic thin film is reduced, and the occurrence of cracks and cracks on the magnetic substrate side can be significantly reduced.

[Example] Hereinafter, the present invention will be described in detail based on the example shown in the drawings.

The inventor investigated the cause of cracks and cracks caused by thermal stress in magnetic thin films formed by thin film deposition methods such as sputtering, and found that there is a strong correlation with the amount of H atoms present in the magnetic thin film. Understood.

If a large number of H atoms exist in the magnetic fJ model, the transition speed of the magnetic material will increase.

Furthermore, since H has a high mobility even at low temperatures, it was found that even if the binding energy is small, it aggregates, forming clusters, etc., and collectively has a significant effect on dislocation motion.

Therefore, in this embodiment, in order to reduce the H atoms in the magnetic f1 film, the HI3 degree of the thin film deposition atmosphere was sufficiently controlled.

Specifically, the H2 partial pressure in the sputtering atmosphere is set to 1
0.07all or less to reduce the number of H atoms incorporated into the magnetic thin film.

An example of film formation in the above-mentioned atmosphere is shown in Figure 1 (
Shown in a) to (d).

FIG. 1(a) shows the warped state when the sendust film l is formed on the ferrite substrate 2 and then returned to room temperature, and compressive stress is generated that makes the sendust film l1l side a convex surface.

FIG. 1(b) shows the case where the above-mentioned sample is heated to 600° C. As in the conventional case, the convex surface on the sendust film l side becomes larger and the compressive stress increases.

In addition, Figure 2 (C) shows the case where the above-mentioned sample is held at 600°C. In this case, unlike the conventional case, there are fewer H atoms in the sendust film, so dislocations in the sendust film are less likely to occur. Either no stress relaxation occurs, or even if stress relaxation occurs, its value is small.

On the other hand, FIG. 1(d) shows the case where the above-mentioned sample is returned to room temperature.Since the stress relaxation when kept at 600°C is small, the ferrite substrate 2 becomes almost flat, and as shown in FIG. 1(a). Return to the original state shown in .

Even when returning to the state shown in FIG. 1(a), the tensile stress on the concave side of the magnetic substrate 2 is small, and no cracks or cracks occur.

In general, ferrite has a convex surface under compressive stress of 10
Although it can withstand about 109 dyn/cm, it can withstand tensile stress of 4 x 10' dyn/c which causes a concave surface.
is the limit.

In this example, since the heat treatment process shown in FIGS. 1(a) to 1(d) is performed, the value of tensile stress is reduced and cracks and cracks in the ferrite substrate are reduced.

In addition to evacuation using a cryopump or the like, it is necessary to use a pump with a high hydrogen evacuation speed such as a turbo molecular pump in combination with the evacuation pump for sputtering charging.

Furthermore, hitting the sputtering surface with an inert gas using a bias sputtering method is extremely effective in expelling H atoms.

In the above-described embodiments, ferrite is used as the substrate and sendust is used as the magnetic film, but the material is not limited to these and other materials can be selected.

Further, the behavior of hydrogen is greatly involved in the dislocation phenomenon of nonmetallic and metallic films, and the above-mentioned technique can be applied to all deposited thin films.

[Effects] As is clear from the above description, according to the present invention, since the magnetic thin film is deposited in a deposition atmosphere with an H2 partial pressure of 10 Toll or less, a structure in which the magnetic thin film is deposited is adopted. Since there are few H atoms, cracks or cracks do not occur on the substrate side, and the magnetic thin film does not peel off.

[Brief explanation of drawings]

FIGS. 1(&) to (d) are explanatory diagrams of a heat treatment process for explaining one embodiment of the present invention, and FIGS. 2(&) to (d) are explanatory diagrams of a conventional heat treatment process. l... Sendust film 2... Ferrite substrate first
Figure (b) M2 diagram

Claims (1)

[Claims] 1) In a magnetic thin film formed on a substrate by a thin film deposition method, the atmosphere in which the magnetic thin film is deposited has a H_2 partial pressure of 10^-^.
A magnetic thin film characterized in that it is formed at less than 1^0Toll. 2) The magnetic thin film according to claim 1, wherein the magnetic thin film is made of a Fe-Al-Si alloy.