JPS5814326A - Production for magnetic recording medium - Google Patents

Abstract

PURPOSE:To improve the efficiency of vapor-deposition, by forming a magnetic layer on a substrate by a specific vacuum deposition method in the continuous production for a vertically magnetized recording medium. CONSTITUTION:A substrate 1 consisting of high-polymer materials which is fed from a supply roll 3 is wound up around a take-up roll 4 through a cylindrical can 2 which is rotated in the direction of an arrow A, and the steam from a vaporization source (such as Co-Cr alloy) 6 heated and melted by the irradiation of the electron beam is vapor-deposited to the substrate 1 through a slit S formed with masks 5 and 5 to form a vertically magnetized recording medium during this winding. In this vapor-deposition, the incidence angle (the acute angle between the normal direction of the substrate 1 and the incidence direction of the vaporized metal to the substrate 1) of the vaporized metal to the substrate 1 in the initial stage of formation of the magnetic layer (angle phi1) is made smaller than that in the latter stage of formation of the magnetic layer (angle phi2) (i), and the electron beam is irradiated to the vaporization source 6 so that an acceleration direction B faces to a movement direction A of the substrate 1 (ii).

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for manufacturing a magnetic recording medium suitable for perpendicular recording.

A perpendicular recording method is a magnetic recording method with excellent short wavelength recording characteristics. This method requires a perpendicular recording medium whose axis of easy magnetization is perpendicular to the film surface of the medium. When a signal is recorded on such a medium, the residual magnetization is oriented perpendicularly to the film surface of the medium, and therefore, the shorter the signal wavelength, the smaller the demagnetizing field within the medium, resulting in excellent reproduction output.

Currently used perpendicular recording media use CO2 directly on a non-magnetic substrate or through a soft magnetic thin film such as permalloy.
A magnetic layer containing Cr and Cr as main components and having an axis of easy magnetization in the perpendicular direction is formed by a sputtering method. Co
In the sputtered film mainly composed of and Or, the amount of Cr is about 30
In the range below 9% by weight, the crystal system has a close-packed hexagonal structure, and by orienting its C axis in a direction perpendicular to the film surface,
Since it is possible to reduce the saturation magnetization until the anisotropic magnetic field in the perpendicular direction becomes larger than the demagnetizing field, a perpendicularly magnetized film can be realized.

However, when forming such a perpendicularly magnetized film, it is difficult to produce a perpendicularly magnetized film at low cost using the sputtering method because the speed of forming a magnetic thin film is slow. In contrast to the sputtering method, according to the vacuum evaporation method (including methods that ionize some of the evaporated atoms, such as the ion blating method),
For example, Co-C can be formed at a high formation rate of several thousand λ/sec.
The inventors have discovered that a perpendicular magnetization film of r can be obtained.

In the vacuum evaporation method, a tape-shaped perpendicular recording medium can be obtained with high productivity by forming a thin film while moving the substrate along the circumferential side of a cylindrical can. Here, a method for forming a perpendicularly magnetized film by vapor deposition will be explained with reference to FIG.

As shown in the figure, a substrate 1 made of a polymer material runs along a cylindrical can 2 in the direction of arrow A. Evaporation source 6
A mask 6 is disposed between the can 2 and the cylindrical can 2, and the evaporated atoms pass through the slit S and adhere to the substrate 1. 3
, 4 are a supply roll and a take-up roll for the substrate 1, respectively.

For example, in order for a Co-Cr vapor deposited film to become a perpendicular magnetization film,
It is necessary for the C axis of the dense hexagonal structure to be oriented perpendicularly to the film surface, and for this purpose, the width of the slit S is narrowed so that only the components of the evaporated atoms that are close to normal incidence are attached to the substrate 1. There must be. However, if the width of S is narrowed, the adhesion efficiency V of evaporated atoms will become smaller.

However, η is Number of atoms attached to the substrate Defined by

The present invention provides a method for manufacturing a perpendicularly magnetized film that increases the adhesion efficiency η without deteriorating the C-axis orientation.

The present invention will be explained below using the drawings.

In Figure 1, ψ1 is the incident angle of evaporated atoms in the early stage of film formation (the acute angle between the normal direction of the film and the direction of incidence of the evaporated atoms on the substrate is called the incident angle), and ψ2 is the incident angle of evaporated atoms in the late stage of film formation. indicates the angle of incidence of

If ψ and ψ2 are reduced by narrowing the width of the slit, the orientation of the C-axis will improve, but the adhesion efficiency will decrease. Figure 2 shows Go-
FIG. 3 is a diagram showing the relationship between ψ of a Cr vapor deposited film, C-axis orientation, and adhesion rate η. However, the orientation of the C-axis is expressed by the half-value width Δθ6° of the rocking curve regarding the (002) plane. The smaller Δθ6° is, the better the C-axis orientation is, and if Δθ5° is about 100 or less, the Go-Cr vapor deposited film can be used as a perpendicular magnetization film.

If it is more than that, the in-plane direction becomes the axis of easy magnetization without forming a perpendicularly magnetized film. Curves 7 and 8 in Figure 2 are Δθ6, respectively.
The relationship between ° and 9 and the relationship between η and ψ are shown. From this figure, when ψ° is 13° or less, Δθ6° is 10° or less, and the Co-Cr vapor deposited film becomes a perpendicular magnetization film, but when ψ is 13° or less, Δθ6° is 10° or less.
If the temperature exceeds 100°, it will not become a perpendicularly magnetized film. Therefore, when ψ1=ψ2, the maximum value of the adhesion efficiency η when forming a perpendicularly magnetized film using the vacuum evaporation apparatus used in this experiment is about 0.3 from FIG. '2.

The composition of the film is 80 wt% Co and 20 wt% Cr. On the other hand, FIG. 3 shows Δθ5° and sign when ψ2 is varied with ψ constant at 10''.

Curves 9 and 10 are the relationship between Δθ6o and ψ2 and η
The relationship between and ψ2 is shown below. In this case, unlike the case in FIG. 2, Δθ6° hardly changes even if ψ2 changes within the range of 3° to 36°. On the other hand, when ψ2 is increased, η becomes larger. For example, when ψ2 is set to 30 OK, η is O, S, and the film is perpendicularly magnetized. The composition of the film is the same as in Fig. 2 (for 20 wt Cr and 20 wt Cr, if ψ1 is 13° or less, that is, in Fig. 3, Δθ
In the case of ψ1 such that 6o is 10° or less, even if ψ2 is changed in the range of 3° to 36° in the same way as above, Δθ6
A Co--Cr perpendicular magnetization film can be obtained with almost no change in angle. On the other hand, FIG. 4 shows Δ06° and η of a film having the same composition as in FIG. 2 when ψ2 is kept constant at 10° and ψ is varied.

Curves 11 and 12 show the relationship between Δθ6o and ψ and the relationship between V and ψ, respectively. In this case, the relationship between Δθ6° and ψ1 becomes 40 if ψ is increased, as in the case of Fig. 2.
Since the diameter increases by as much as 6°, Co-
It is difficult to obtain a 0r perpendicular magnetization film. Therefore, it is recommended to set ψ1 at an angle such that Δθ6° is 10° or less in Figure 2 (this angle varies depending on the vapor deposition equipment and deposition conditions), and to set ψ2 to be larger than ψ1. , a Go-Cr perpendicular magnetization film can be obtained with high deposition efficiency.

As described above, according to the method of the present invention, it is possible to increase the adhesion efficiency without deteriorating the C-axis orientation.

In the above, a case has been described in which a thin film is formed while the substrate 1 is moved along the circumferential surface of a cylindrical can, but as shown in FIG. The same thing can be said when performing. In other words, in this case also ψ.

A perpendicularly magnetized film can be obtained with high adhesion efficiency by increasing ψ2.

Another condition that can be used to further increase the effect so far is that the evaporated atoms are obtained by using accelerated electrons, and that the acceleration direction of the so-called electron beam (B in Figure 1) is in the direction of movement of the substrate. The key is to choose conditions that are opposite to A (the relationship shown in Figure 1). More preferably,
The cross-sectional shape of the pool of the evaporation source container is set to ψ, >ψ2.

This adds an effect that is probably due to the appearance of directionality in the vapor distribution of evaporated atoms. An example of this is shown in FIG.

That is, when compared under the same conditions as in FIG. 3, the adhesion efficiency η can be extremely high. Therefore, the perpendicular magnetization film is C6-V outside the Co-Cr film.

Although it can also be obtained with Co-Mo, Go-W, barium ferrite films, etc., the method of the present invention is effective for any film.

Furthermore, it is also possible to create a double-sided disc using this invention, and there are no limitations on the form or structure of the medium.

As described above, according to the present invention, a perpendicularly magnetized film can be obtained with high deposition efficiency by vacuum evaporation.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing a case where a magnetic thin film is formed while moving a substrate along the circumferential side of a cylindrical can in the method for manufacturing a magnetic recording medium according to the present invention, FIGS. 2, 3, and 4. and FIG. 6 are diagrams showing the relationship between the incident angle of evaporated atoms and the orientation and adhesion efficiency of the magnetic thin film in the method of manufacturing a magnetic recording medium according to the present invention, respectively. In a method for manufacturing a recording medium, a magnetic thin film is formed while moving a substrate along a flat plate.
It is a figure which shows the case where Ik is chanted. 1... Board, 2... Cylindrical can, 5
...Mask, 6...Evaporation source, 13...
...Flat plate. Name of agent: Patent attorney Toshio Nakao and 1 other person No. 1
Figure 2 Figure t/Shin) Figure 3 Lpl, <degree)

Claims (1)

[Claims] When forming a magnetic layer whose axis of easy magnetization is perpendicular to the film surface by vacuum evaporation on a moving substrate, the incident angle of evaporated atoms at the early stage of magnetic layer formation is the same as the incidence angle at the later stage of magnetic layer formation. A magnetic recording medium characterized by using accelerated electrons as an energy source for obtaining evaporated atoms so that the direction of acceleration of the electrons and the direction of movement of the substrate are opposite to each other. Production method.