JPH06309665A - Method of manufacturing magnetic recording medium - Google Patents

Abstract

(57) [Abstract] [Purpose] In oblique vapor deposition using a continuous vapor deposition apparatus, it is possible to reduce the effect of excess oxygen existing in a region with a low vapor density on the characteristic deterioration of the magnetic layer and improve the recording / reproducing characteristics. Try. [Structure] Introducing oxygen into a vacuum container and forming a magnetic layer on a long polymer substrate 5 running on the circumferential surface of a cylindrical can 8 by continuous vapor deposition. 4 is placed between the cylindrical can 8 and the shielding plate 3b that regulates the incident angle of vaporized atoms at the end of the formation of the magnetic layer to the polymer substrate 5, and the vaporized atoms at the initial stage of magnetic layer formation are incident on the polymer substrate 5. The rare earth atom, the yttrium atom, or a mixture thereof is evaporated in the vicinity.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of manufacturing a magnetic recording medium having excellent high density recording / reproducing characteristics.

[0002]

2. Description of the Related Art At present, magnetic recording / reproducing devices tend to be smaller and have higher densities, and metal thin film type media have been attracting attention as exceeding the limit of high density of conventional coating type media.
In this regard, a metal thin film type medium containing Co, Ni and O as main components has been put to practical use as a magnetic tape for a VTR and is commercially available. In order to form such a magnetic recording medium with high productivity, for example, a continuous vacuum vapor deposition device using a cylindrical can is used to continuously deposit a magnetic layer on a long polymer substrate while moving it. do it.

At this time, oxygen is introduced into the vacuum container to make the magnetic layer a ferromagnetic thin film of partial oxides of Co and Ni, and the oblique evaporation technique is used to make the magnetic layer have a film surface. Has a magnetization component in the perpendicular direction, and the contribution thereof improves the high density recording / reproducing characteristics as compared with the conventional coating type medium. The metal thin film type magnetic tape according to the above technique is expected to be applied as a magnetic tape corresponding to a next-generation home compact digital VTR, particularly a high-definition digital VTR.

[0004]

In the magnetic layer mainly composed of Co and O or Co, Ni and O formed by introducing oxygen by the manufacturing method using the above continuous vapor deposition apparatus, Co (Co And a profile of the composition ratio of Ni) and oxygen in the thickness direction of the magnetic layer is examined, the proportion of oxygen in the initial portion of the magnetic layer formation (the vapor density of Co or the like is small) becomes larger than that in other portions. In a particularly remarkable example, it was found that the composition ratio was 1: 1 near the surface of the polymer substrate.

This means that the initial formation portion of the magnetic layer is almost non-magnetic. That is,
In the conventional manufacturing method, it is considered that there is a portion having inferior magnetic properties near the surface of the polymer substrate, which is the initial portion of the formation of the magnetic layer, and the magnetic properties are improved as it approaches the surface side of the magnetic layer. The existence of such a portion near the surface of the polymer substrate is
It deteriorates the magnetic properties of the entire magnetic layer. Further, it is not preferable from the viewpoint of improving the recording / reproducing characteristics that the magnetic characteristics are distributed with a large difference in the thickness direction of the magnetic layer. From the above viewpoint, C in the initial portion of the magnetic layer formation
There is a need for a manufacturing method in which the composition ratio of o (Co and Ni) to oxygen is approximately the same as in the vicinity of the surface of the magnetic layer, and the compositional distribution of oxygen in the thickness direction of the magnetic layer is substantially constant.

[0006]

SUMMARY OF THE INVENTION The present invention provides a method for producing a metal thin film magnetic tape which is more preferable from the viewpoint of the above-mentioned problems, in which oxygen is introduced into a vacuum container, and a cylindrical can is formed by continuous vapor deposition. In the oblique deposition process of forming a magnetic layer on a long polymer substrate running on the peripheral surface of the substrate, the oxygen introduction part is shielded to regulate the incident angle of vaporized atoms to the polymer substrate at the end of the magnetic layer formation. It is characterized by being placed between a plate and a cylindrical can, and vaporizing rare earth atoms, yttrium atoms, or a mixture thereof in the vicinity of the vaporized atoms in the initial stage of magnetic layer formation that are incident on the polymer substrate. .

[0007]

According to the present invention, the oxygen introduction portion is arranged on the final side of the magnetic layer formation so that the oxygen amount on the initial side of the magnetic layer formation where the vapor density of Co or the like is low is as small as possible. Further, according to the present invention, the oxygen circulated to the initial side of the magnetic layer formation can be preferentially bonded to the vaporized atoms of rare earth or yttrium which are more easily oxidized than the metal atoms such as Co constituting the magnetic layer. It is possible to prevent excess oxygen from being contained in the layer on the initial side of layer formation.

[0008]

EXAMPLE FIG. 1 shows an example of the structure of a continuous vapor deposition apparatus for realizing the manufacturing method of the present invention. In this figure, 5 is a long polymer substrate, and 6 and 7 are polymer substrates 5, respectively.
Supply roll and take-up roll. Polymer substrate 5
While traveling on the circumferential surface of the cylindrical can 8 in the direction of the arrow 9, evaporated atoms of Co evaporated from the evaporation source 1 are deposited. The incident angle of the vaporized atoms is regulated by the pair of shield plates 3a and 3b. Further, oxygen is introduced through the oxygen introduction tube 4 to form a ferromagnetic layer made of a partial oxide by reactive vapor deposition.

The following points can be considered as a cause of the composition ratio of oxygen to Co in the initial portion of the magnetic layer becoming larger than that in the vicinity of the surface of the magnetic layer. First, when the magnetic layer is formed by the continuous vapor deposition apparatus as shown in FIG. 1, the incident angle of the vaporized atoms to the polymer substrate 5 continuously changes from the initial formation portion to the final formation portion. The incident angle of the vaporized atoms forming the initial part in the vicinity of the polymer substrate surface is a region where the incident angle is high with respect to the polymer substrate normal, and the attachment efficiency of the vaporized atoms is low.
Since the distance from the evaporation source is large and the vapor density is low, the proportion of oxygen in the film is relatively high.

In consideration of this, in the apparatus shown in FIG. 1, the oxygen introducing tube 4 is provided with a shielding plate 3b and a cylindrical can 8 for restricting the incident angle of vaporized atoms to the polymer substrate 5 at the final stage of formation of the magnetic layer. The oxygen amount on the initial side of formation of the magnetic layer is reduced as much as possible. However,
Oxygen introduced at the final stage of formation of the magnetic layer does not all bond with metal atoms such as Co, but a part thereof becomes an excess. This excess oxygen also wraps around from the final stage of formation of the magnetic layer to the initial stage of formation of the magnetic layer in the high incident angle region.

Therefore, in the present manufacturing method, the rare earth atoms or the yttrium atoms are evaporated from the evaporation source 2 for oxidation in the vicinity of the evaporated atoms at the initial stage of forming the magnetic layer, which are incident on the polymer substrate 5. These rare earth or yttrium vaporized atoms form Co that constitutes the magnetic layer.
Since it is more easily oxidized than the metal atoms such as the above, it preferentially bonds with oxygen that has circulated to the initial side of the magnetic layer formation, and can prevent excess oxygen from being contained in the magnetic layer.

Next, this embodiment will be described more specifically.

Using the apparatus shown in FIG. 1, a magnetic layer containing Co and O as main components was formed on a polymer substrate using Co as the evaporation source 1 of the magnetic material. In the present embodiment, the oxidation evaporation source 2 is G
d. In the configuration of FIG. 1, the relative positional relationship between the evaporation source 2 for oxidation, the evaporation source 1 of the magnetic material, and the shield plate 3a is prevented so that the evaporated atoms of rare earth or yttrium evaporated from the evaporation source 2 for oxidation are not mixed in the magnetic layer. Also, the vapor density distribution of rare earths or yttrium must be fully considered. From this viewpoint, it is more preferable to install a shielding plate that shields between the evaporation source 2 for oxidation and the evaporation source 1 of the magnetic material, if necessary. As a result of composition analysis of the magnetic layer produced in this example, the composition ratio of Gd atoms in the magnetic layer was 0.2 atomic% or less, and it was confirmed that there was almost no mixing.

FIG. 2A shows a composition profile of Co, oxygen, and carbon in the thickness direction of the magnetic layer obtained by Auger spectroscopic analysis in the magnetic layer containing Co and O as main components manufactured in this example. An example is shown. Further, as a comparative example, an example of an analysis result of a magnetic layer containing Co and O as main components, which is produced without evaporating Gd by the oxidizing evaporation source 2, is also shown in (b). The carbon was analyzed in order to more clearly understand the boundary surface between the magnetic layer and the polymer substrate.

In the comparative example shown in (b), it can be seen that the composition ratio of oxygen to Co is increased toward the substrate side of the magnetic layer, and the oxygen concentration distribution is large in the thickness direction of the magnetic layer. On the other hand, in the magnetic layer according to the manufacturing method of the present embodiment shown in (a), oxygen C
The composition ratio with respect to o is almost constant, and it can be seen that the oxygen concentration distribution in the thickness direction of the magnetic layer is improved as compared with (b).

Further, in the film surface of the magnetic layer in the present example and the comparative example, a magnetization curve when a magnetic field is applied in the running direction of the polymer substrate when the magnetic layer is formed, that is, in the tape longitudinal direction when forming a magnetic tape. Was measured by a vibrating sample magnetometer. As a result, the squareness ratio was 0.85 in the comparative example, while it was improved to 0.9 in the magnetic layer according to the present example.
It is considered that this is because the magnetic properties in the initial portion of the magnetic layer formation were improved, and thus the distribution of the magnetic properties in the thickness direction of the magnetic layer was suppressed, and the magnetic properties of the entire magnetic layer were improved.

Further, the polymer substrate having the magnetic layer formed according to the present embodiment and the comparative example is cut into a magnetic tape,
Recording and reproducing characteristics were measured using a drum tester. As a result, it was confirmed that the C / N of the magnetic tape having the magnetic layer according to this example was about 2 dB higher than that of the magnetic tape having the magnetic layer according to the comparative example at the wavelength of 0.5 μm.

Even when a rare earth element other than Gd, yttrium, or a mixture of at least two of them is used as the evaporation source 2 for oxidation, the present invention can be obtained by preferentially bonding with oxygen over Co. The effect of was confirmed. On the other hand, even when a material such as Mg or Ti is used for the oxidation evaporation source 2, the effect of preventing excess oxygen content in the initial portion of the magnetic layer formation is obtained by preferentially bonding with oxygen over Co. To be However, when a material that becomes a gas phase by sublimation is used, these atoms are mixed in the magnetic layer at a ratio of several atomic% or more, which rather deteriorates the magnetic properties.

In addition to Co as the evaporation source 1 of the magnetic material,
Even when Fe, Ni or a mixture of at least two of them is used, the effect of the present invention of improving the oxygen concentration distribution in the thickness direction of the magnetic layer was obtained as in the above.

[0020]

According to the manufacturing method of the present invention, the oxygen concentration distribution can be made substantially constant in the layer thickness direction of the magnetic layer formed by continuous vapor deposition by introducing oxygen into the vacuum container. It is possible to prevent deterioration of magnetic properties due to excess oxygen content in the initial portion of layer formation. As a result, it is possible to prevent the magnetic characteristics from being distributed with a large difference in the thickness direction of the magnetic layer, and it is possible to improve the recording / reproducing characteristics.

[Brief description of drawings]

FIG. 1 is a schematic view showing a configuration example of a continuous vapor deposition apparatus for realizing the manufacturing method of the present invention.

FIG. 2 Co, oxygen, obtained by Auger spectroscopy
FIG. 3 is a diagram showing the composition profile of carbon in the thickness direction of the magnetic layer in comparison between the present example (a) and the comparative example (b).

[Explanation of symbols]

1 evaporation source of magnetic material 2 evaporation source of rare earth, yttrium, or a mixture thereof 3a shielding plate 3b shielding plate 4 oxygen introducing pipe 5 polymer substrate 6 supply roll 7 winding roll 8 cylindrical can 9 cylindrical can Direction of rotation

Claims (1)

[Claims] 1. An oxygen introduction part in an oblique vapor deposition process in which oxygen is introduced into a vacuum container and a magnetic layer is formed on a long polymer substrate running on the circumferential surface of a cylindrical can by continuous vapor deposition. Is placed between the shield and the cylindrical can that regulates the incident angle of vaporized atoms at the end of the magnetic layer formation onto the polymer substrate, and in the vicinity of the vaporized atoms at the initial stage of magnetic layer formation on the polymer substrate A method of manufacturing a magnetic recording medium, which comprises vaporizing atoms, yttrium atoms, or a mixture thereof.