JPS641851B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a method of manufacturing a magnetic recording medium such as a magnetic tape or a magnetic disk, and particularly aims to provide a method of manufacturing a magnetic recording medium constructed using a magnetic thin film with high coercive force. Cobalt, iron, nickel, magnetic recording media
Alternatively, a magnetic thin film with high coercive force made of an alloy containing at least these materials can easily reduce the thickness δ of the magnetic layer, thereby reducing the thickness loss of the magnetic layer and recording. wavelength λ
Since it is possible to shorten the wavelength, that is, to record up to a short wavelength range, it is seen as a promising medium for high-density recording. However, to explain the conventional method of manufacturing such ^a magnetic thin film using ^FIG . melting and evaporating a melt 3 of cobalt, iron, nickel, or an alloy containing at least these;
The evaporated particles were deposited on the surface of a substrate 4 which was arranged so that the perpendicular direction of the surface to be evaporated was inclined at an angle α with respect to the direction of incidence of the evaporated particles. The magnetic properties of a magnetic thin film made by such an oblique deposition method depend on the angle α, and in order to obtain the characteristics of high coercive force Hc, an inclination of α = close to 90° is required. There was a problem in terms of yield. As is clear from a simple calculation of when α is 0° and when α is 80°,
cos0°/cos80°≒10, and when the substrate 4 is tilted at α=80°, nearly 10 times the amount of melt 3 must be used compared to when α=0° without tilting. Furthermore, since cobalt is one of the rare resources and an expensive metal, it is economically very undesirable to waste it. For this reason, the conventional method of obtaining a magnetic thin film using the oblique vapor deposition method has had a major problem in terms of cost. The present invention is based on the cause of the high coercive force of magnetic thin films. Taking cobalt as an example, cobalt is crystallographically hexagonal and has magnetocrystalline anisotropy energy on the order of 10° ergs/cc with its C-axis direction as the easy direction. On the other hand, a cobalt film with high coercive force manufactured by oblique evaporation method, for example, when α = 80°, uses Kα rays of Cu as a radiation source, and according to the ASTM standard,
When examined by line diffraction, the intensity from the (OO2) plane I
The ratio of (002) to the sum of intensities from all sides I(002)/
The value of ΣI(hkl) (h, k, l indicate surface index) is
It is very small at 0.2. Therefore, a cobalt film made by oblique evaporation has very little C-axis component in the direction perpendicular to the surface of the substrate;
Most of the axial components are parallel to the substrate surface.
When examining magnetic properties, the direction parallel to the direction of incidence of evaporated particles that is easily magnetized and exhibits high coercive force (C-axis direction)
The coercive force in the direction perpendicular to the direction of incidence and in the direction perpendicular to the plane of the substrate is only about half of the value in the direction parallel to the direction of incidence. On the other hand, if α=0°, that is, if a cobalt film is manufactured without tilting the substrate with respect to the incident direction of the evaporated particles, then according to the X-ray diffraction results, I(002)/ΣI
(hkl) indicates a value of 0.8 or more. Therefore, α=
At 0°, most of the C-axis components are considered to be oriented in a direction perpendicular to the plane of the substrate. Examining the magnetic properties,
In the direction perpendicular to the plane of the base, that is, in the C-axis direction, approximately
300 oersted, and the coercive force in the direction perpendicular to the direction of incidence is approximately half the value in the direction perpendicular to the plane of the substrate. Regarding the relationship between the crystallographic conclusion and the magnetic property results at α=0° and 80°, it is considered that the coercive force is higher in the direction in which the C-axis component is oriented more. Therefore, when cobalt is used as a magnetic recording medium, for example in a magnetic tape, in order to increase the coercive force in the direction parallel to the magnetic tape surface,
It is important to orient the C-axis component of the cobalt film in a direction parallel to the longitudinal direction of the tape. The present invention provides C
A nonmagnetic layer with a crystallographic hexagonal structure with many axial components oriented is prepared in advance under specific conditions.
Furthermore, by forming a hexagonal magnetic thin film on this nonmagnetic layer, the above-mentioned problems in terms of characteristics and economy can be solved. The details will be explained below. FIG. 2 shows an example of the structure of a magnetic recording medium according to the present invention. In the figure, reference numeral 11 denotes a non-magnetic supporting substrate, which is made of, for example, resin such as polyethylene terephthalate, polyamide, or polyimide, aluminum, stainless steel, or glass. Reference numeral 12 denotes a nonmagnetic layer, which is a hexagonal thin film grown preferentially so that a large amount of the C-axis component is oriented in a direction parallel to the surface of the support 11. Titanium is effective as its constituent material. Reference numeral 13 denotes a hexagonal magnetic thin film, which is laminated on the underlying nonmagnetic layer 12 at an angle close to α=0°. Cobalt is effective as a material for the magnetic thin film 13, and other examples include hexagonal alloys such as cobalt-iron and cobalt-nickel.
This hexagonal magnetic thin film 13 grows under the influence of the hexagonal non-magnetic layer 12 which is preferentially grown so that many C-axes are oriented in the direction parallel to the surface of the support base 11. Many of the C-axis components are oriented in the direction parallel to the plane of . The above explanation has been based on the case where the magnetic thin film is a single layer, but even if the magnetic thin film has a multilayer structure including a non-magnetic intermediate layer, this intermediate layer has a hexagonal crystallographic structure and a supporting substrate. The object of the present invention can be achieved if the thin film has a large number of C-axis components oriented in a direction parallel to the plane. In order to preferentially grow an underlayer and an intermediate layer in which a large amount of the C-axis component is oriented in a direction parallel to the surface of the supporting substrate, the direction perpendicular to the surface of the substrate to be evaporated is tilted with respect to the direction of incidence of the evaporated particles. For example, when stacking titanium films, the formation speed is an important parameter. In other words, a titanium film with the desired crystallographic properties cannot be obtained at a formation rate of 30 Å per minute, and a titanium film with the desired properties cannot be obtained at a formation rate of 2000 Å per minute or more. It can be formed easily. Hereinafter, a detailed explanation will be given based on examples. Example 1 On a non-magnetic supporting substrate made of soda glass, a crystal with a hexagonal crystal structure and C
A titanium layer with many axial components oriented was formed. In order to preferentially grow the titanium underlayer so that most of the C-axis components are parallel to the plane of the supporting substrate, titanium is laminated by an oblique vapor deposition method. That is, here, in a container with a vacuum of 10 ^-5 Torr, the incident angle α = 70°, the temperature of the supporting substrate 200°C, and the deposition rate.
A titanium layer with a thickness of 2.5 μm was formed under the conditions of 2000 Å/min. When this titanium layer was examined by X-ray diffraction using Cu's Kα rays as a radiation source, as shown in Figure 3, no intensity was observed in the (002) plane perpendicular to the C-axis direction at a diffraction angle of 2θ. That is, it can be seen that no C-axis component is observed in the direction perpendicular to the surface of the support substrate, and that a large amount of C-axis component is oriented in the direction parallel to the surface of the support substrate. Cobalt was evaporated onto the titanium layer thus obtained under conditions of vacuum degree 10 ^-5 Torr, α = 20°, evaporation rate 1.5 Å/min, and substrate temperature approximately room temperature.
A magnetic thin film was formed. The coercive force is shown in Table 1. For comparison, cobalt was deposited on a glass support substrate under the same conditions as described above without providing a titanium layer to form a magnetic thin film, and its coercive force was examined. The results of the comparative example are also shown in Table 1.

[Table] The measurement direction in Table 1 is the direction parallel to the longitudinal direction of the glass substrate 11 as shown in _FIG .
The width direction of the base is X ₂ , the direction perpendicular to the surface of the base is X ₃
The coercive force along the longitudinal direction of the support substrate, which is effective for planar magnetization, was increased by about three times compared to the comparative example without a base. As is clear from these results, according to the present invention, the coercive force in the _X1 direction is greatly improved by three times compared to the case where a hexagonal nonmagnetic layer is not provided as an underlayer. Example 2 A titanium underlayer and a cobalt magnetic thin film were sequentially formed on a glass support substrate under the same conditions as in Example 1 except that the thickness of the titanium layer was 0.1 μm. For comparison, without forming a hexagonal nonmagnetic layer,
A cobalt magnetic thin film was formed on a glass supporting substrate. For each, the coercive force was measured in the same manner as in Example 1. The results are shown in Table 2.

[Table] As is clear from the results in the above table, a cobalt magnetic thin film with a large coercive force can be obtained even if the thickness of the hexagonal nonmagnetic layer is on the order of 0.1 μm.

[Brief explanation of drawings]

FIG. 1 is a diagram showing a conceptual configuration of a vapor deposition apparatus for explaining the oblique vapor deposition method, FIG. 2 is a cross-sectional view showing an example of the structure of a magnetic recording medium according to the present invention, and FIG.
The figure shows an example of X-ray diffraction of the titanium underlayer, and FIG. 4 is an explanatory diagram when measuring the coercive force of the cobalt magnetic thin film. 11...Supporting base, 12...Nonmagnetic layer, 13...
...Magnetic thin film.

Claims (1)

[Claims] 1. On a non-magnetic supporting substrate, evaporated particles of titanium having a hexagonal crystallographic structure are incident on the supporting substrate at an evaporation formation rate of 2000 Å/min or more at an angle inclined to the direction perpendicular to the surface of the supporting substrate. A method for manufacturing a magnetic recording medium, comprising forming a nonmagnetic layer on the surface of the supporting substrate, and then forming a hexagonal magnetic thin film thereon.