JPS5924445A - Manufacture of magnetic recording medium - Google Patents

Abstract

PURPOSE:To improve performance and productivity satisfactorily when a ferromagnetic layer is formed, by setting the angle of incidence of an electron beam to the vaporizing surface of ferromagnetic material to <=45 deg. and the angle of incidence of vapor to a high polymer substrate to >=40 deg. when directing the vapor to the substrate in movement. CONSTITUTION:When the substrate 1 moves along a rotating support body 3, the ferromagnetic layer is formed on the substrate 1, but vapor flow radiated from the molten ferromagnetic material in a vapor deposition source container 5 has an angle distribution; thin-film formation starts with 90 deg. incidence and the speed of the vapor deposition increases to a maximum speed (thetamax) as the angle of incidence decreases, and then decreases to the contrary; and the vapor flow is cut off with a mask 7 and the formation is completed. When the thetamax exceeds 40 deg., a reflected electron is injected into a high polymer molding within a condition range by setting the angle thetae of incidence to <=45 deg., the effect that electrostatic attracting force with the grounded rotating support body is enhanced by an electrostatic field based upon a spatial charge distribution, cooling effect becomes more effectively to suppress thermal deterioration of the substrate, expecting the improvement of the productivity.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for manufacturing a metal thin film magnetic recording medium.

More specifically, the present invention relates to a method that satisfies improvement in performance and productivity when forming a ferromagnetic layer by electron beam evaporation and ion blating.

In recent years, there has been remarkable progress in high-density recording in the field of magnetic recording, and metal thin-film magnetic recording media made by vapor deposition have been put to practical use in audio applications, while there are also suggestions of technological possibilities for adapting them to video applications. , development is active in various fields.

Particularly in short wavelength recording, a medium that exhibits excellent characteristics requires a coercive force close to 100,000, so it is important to find a method that can be expected to significantly improve productivity. It's coming.

Generally, recording media, except for hard disks, use flexible polymer molded substrates.

When polyester, which is the most versatile material, is used as a substrate, the main problem during vapor deposition is thermal degradation.

In order to improve productivity, the method of increasing the evaporation rate by forcibly increasing the input power has an upper limit due to the thermal deterioration mentioned above. Therefore, (b) it is important to effectively release heat to the shaft support.

The present invention was developed in consideration of these points, and is an improvement on the method of evaporating ferromagnetic material by heating it with an electron beam. When the point of the incident angle component at which deposition occurs at the maximum deposition rate is called the principal incidence, it is important that its value is greater than 4σ and that the angle of incidence of the heating electron beam on the evaporation surface is within 45°. The gist of this is that

Here, the angle of incidence of the electron beam on the evaporation surface is assumed to be horizontal and defined in terms of geometrical optics. Even the slight spread of an electron beam is quantified as defined by the central axis of the electron beam.

FIG. 11 shows the definition thereof, FIG. 2 shows the main structure of the apparatus used to carry out the present invention, and examples will be described in detail below.

As shown in FIG. 2, the polymer molded substrate 1 is 111! It moves along the rolling support 3 and is wound up on the winding shaft 4.

When moving on the rotating support 3, a ferromagnetic layer is formed on the substrate 1, and the vapor flow emitted from the molten ferromagnetic material 6 in the evaporation source container has an angular distribution. The thin film shape becomes narrower from 9 cf' incidence, and as the angle of incidence becomes smaller, the deposition rate increases, eventually reaches a maximum (θmax), and then decreases again, until the mask 7
The formation is completed by being blocked by . This angle is called the minimum incident angle, which is the cut-off incident angle of 00 dimensions [see FIG. 1(B)]. In addition,
Here, θC and θmax may match depending on the setting conditions.

Now, let θe be the angle of incidence of the electronic beer L, 8 used to heat the evaporation source on the evaporation surface (see Figure 1 (C) and Figure 2).
. In addition, the broken line 9tJ in FIG. 1(C) indicates a hypothetical evaporation surface of the ferromagnetic material.

The reason why θmax is selected to be 400 or more is considered to be that the deposition rate with a high incidence component increases, so that the effect seen in the formation of a ferromagnetic thin film by so-called oblique incidence becomes even greater.

This leads to obtaining a high coercive chip.

However, apart from the invention of Japanese Patent Publication No. 19389/1989, which focuses on selecting θmax above 40°C and selecting θ0i above 45°, θC is particularly limited when oxygen is not added during vapor deposition, as shown in the attached example. When you try to use it,
A coercive force equivalent to that disclosed in No. 389 can be achieved with a much smaller awning angle, which directly leads to improved productivity.

The basis for the idea that θe has an angular dependence is that the angular inverse distribution of the vapor flow changes depending on θe, and the angular distribution of backscattered electrons changes.

Both of these can be achieved by selecting the incident angle θe within 45° as long as θmax is 4σ or more in many examples. Due to the electrostatic field caused by the space charge distribution that is formed,
The effect of electrostatic attraction between the rotating support at ground potential becomes stronger and it moves closer to areas with large heat input, so the cooling effect works more effectively and productivity increases. In addition to being able to suppress thermal deterioration of the substrate, changes in vapor flow distribution will act to increase the evaporation rate of components that contribute to foul film formation, and productivity is also expected to improve. It is.

Now, in the embodiment of the present invention, a cylindrical can with a diameter of 1100C is used as the lLi rolling support.
,Ta.

The source of the electron beam is a piercing type electron gun, which is a straight-travel type.
An accelerating voltage of 30 KV was used.

4 plates H, polyethylene terephthalate film (thickness 1
1.5 μm 9 width 5 Q cm) was used. The surface roughness J of the vapor deposition surface and the reflection side surface of the substrate was 460'i. The surface of the rotating support was 0.1S.

The tension of the substrate when entering the rotating support was constant at 5 kg.

The oxygen introduction conditions were also kept constant at 10·5 Torr-β/5ec. The thickness of the obtained magnetic layer was also kept constant at 0.1 μm, and the overlay effect of θmax and θe was investigated in terms of characteristics and productivity under the common conditions of Kukoro et al. The results C1 are shown in the following table. It is like that. Note that θC was kept constant at 30″.

In the table, under the conditions that can prevent thermal deterioration in conventional examples 1 to 3, the board moving speed was 30.27:5゜21 m, respectively.
/min, and its superiority in terms of both productivity and properties is clear.

Here, an example of how to select the conditions for setting θmlX' to 1400 or more will be described below.

The crucible position is shifted from directly below the rotating support (a can with a diameter of 100 cm) to the side opposite to the moving direction of the substrate film.

Assuming that the vapor distribution of the evaporation source radiates directly above,
For example, if the angle α (see Fig. 1 (A)) has a distribution expressed by Cos α, then the crucible shift f
t position (Yo) Yo=23.6cm - 40cm should be the range. Although it may be set to 40 cm to 60 cm, it is not practical because the vapor deposition efficiency gradually decreases.

If the vapor distribution is not maximum right above but has an inclination, it is only necessary to adjust it according to the inclination.

The easiest way to determine it experimentally is to deposit the film while the rotating support is stopped and measure the film thickness distribution. According to this method, two crucible positions are selected (selections are made in the two points mentioned above).
3.5 cm to 40 cm), for example between 24 cm and 3
The conditions for selecting θmax4o0 or more can be easily derived from the results of vapor deposition by selecting two points of 5 cm and holding the substrate in a stopped state.

In order to confirm that the limiting values of θmax and θe are values specific to the above-mentioned system and are not just experimentally found favorable conditions, the can diameter 'fz 30 Cml 50
cm.

In the case of 120cm, the total circumference of the rotating support is 120cm, 180CJ 215cmt 2
90cm stainless steel endless belt (0.2t
), the acceleration voltage of the electron beam is 20
KV, '40KV, 60KV' respectively
The usefulness of the present invention was confirmed.

It was also confirmed that the same effect was obtained even if the substrate material, thickness, surface roughening, and type of magnetic material were changed, and even when applied to an ion grating.

As described above, according to the present invention, a magnetic recording medium with excellent performance can be manufactured with high productivity, and its industrial value is great.

[Brief explanation of drawings]

Figures 1 (A), (B) and (C) are diagrams for explaining the definition of the main incident angle and the electron beam incidence angle on the evaporation surface, and Figure 2 is a diagram for explaining the details of the present invention. It is a diagram. 1...Substrate, 3...Rotating support, 6...
... Evaporation source container, 6 ... Molten metal, 7 ... Mask, 8 ... Electron beam. Name of agent: Patent attorney Toshio Nakao and 1 other person No. 1
Figure 2

Claims (1)

[Claims] A ferromagnetic layer is formed on the substrate by irradiating the ferromagnetic material that forms the evaporation source with an electron beam and directing the magnetism of the evaporated ferromagnetic material to the polymer molded substrate that is moving along the rotating support. A magnetic recording medium characterized in that the total main incident angle of the electron beam on the evaporation surface of the ferromagnetic material is 45 degrees or less, and the total incident angle of the vapor on the substrate is 400 degrees or more. Production method.