JPH07141655A - Production of magnetic recording medium - Google Patents

Abstract

PURPOSE:To obtain a thin film magnetic recording medium having high S/N by providing a vaporizing source with two vaporizing zones along the travelling direction of a substrate when a magnetic layer is formed on the travelling substrate by vacuum deposition. CONSTITUTION:A substrate 1 is supplied from a supply roll 4, travelled along the cylindrical can 2 in the direction of an arrow, and wound on a roll 5. The vapor source 8 has vaporizing zones 11, 12 along the travelling direction of the substrate. The vaporizing zone 11 is disposed near the vertical line 13 crossing the starting part of film forming, while the vaporizing part 12 is disposed near the vertical line 14 crossing the finishing part of film forming. Thus, high productivity can be expected. Vaporized atoms from the vaporizing zones pass through the aperture between shielding plates 3A, 3B and deposit on the substrate 1. An O2 inlet 10 is disposed at the end of the shielding plate 3B and the vapor source 8 is filled with the vapor source material 7. By raising the vaporizing rate in the vaporizing zone 11 higher than that in the vaporizing zone 12, higher S/N can be obtd. The higher the film deposition rate in the starting part of film forming, the higher crystalline orientation of the magnetic layer can be obtd.

Description

Detailed Description of the Invention

[0001]

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

[0002]

2. Description of the Related Art The density of magnetic recording / reproducing devices is increasing year by year, and a magnetic recording medium having excellent short wavelength recording / reproducing characteristics is desired. At present, a coated magnetic recording medium in which magnetic powder is coated on a substrate is mainly used, and the characteristics have been improved so as to satisfy the above-mentioned demand, but it is almost the limit.

Thin film magnetic recording media have been developed to exceed this limit. The thin film magnetic recording medium is manufactured by a vacuum deposition method, a sputtering method, a plating method, etc.
It has excellent short wavelength recording / reproducing characteristics. Examples of the magnetic layer in the thin film magnetic recording medium include Co and Co—N.
i, Co-Ni-P, Co-O, Co-Ni-O, Co
-Cr, Co-Ni-Cr, Co-Cr-Ta, Co-
Cr-Pt and the like are being studied.

From the viewpoint of application to a magnetic tape, Co-O and Co-Ni-O are considered to be most suitable among them, and a vapor deposition tape having Co-Ni-O as a magnetic layer is considered. It has already been put into practical use as a tape for a Hi8 system VTR.

An example of a method of manufacturing a vapor deposition tape for VTR of Hi8 system will be described below with reference to FIG. FIG. 2 shows an example of the internal structure of a conventional vacuum vapor deposition apparatus for producing a vapor deposition tape. A substrate 1 made of a polymer material runs along a cylindrical can 2 in the direction of arrow 6. Evaporated atoms 9 evaporated from the evaporation source 8 containing the evaporation substance 7 adhere to the substrate 1 to form a magnetic layer. An electron beam evaporation source is suitable as the evaporation source 8, and an alloy such as Co or Co—Ni is filled therein as the evaporation material 7. The electron beam evaporation source is used as the evaporation source 8 because
This is because the refractory metal such as o is evaporated at a high evaporation rate.

Shielding plates 3A and 3B are provided in a part of the periphery of the cylindrical can 2 in order to prevent unnecessary evaporated atoms 9 from adhering to the substrate 1. The shield plate 3A regulates the incident angle of vaporized atoms at the film formation start portion to the substrate, and the shield plate 3B
Regulates the angle of incidence of vaporized atoms on the substrate at the film formation end. θ _i is the incident angle at the film formation start portion, and θ _f is the incident angle at the film formation end portion.

An oxygen introducing port 10 for introducing oxygen into the vacuum chamber at the time of vapor deposition is provided at the end of the shielding plate 3B. By optimizing the amount of oxygen introduced, excellent recording / reproducing characteristics and practical characteristics are achieved. A vapor deposition tape is obtained. The substrate 1 is wound around the supply roll 4, and after the magnetic layer is formed, the substrate 1 is wound around the winding roll 5.

[0008]

In the future, thin film magnetic tapes are required to have high productivity as well as high S / N in the short wavelength region.

In order to form a magnetic layer having a high S / N ratio on a moving substrate by a vacuum deposition method, the incident angle θ _{i at} the film forming start portion and the incident angle θ _f at the film forming end portion are increased. It is generally known that this should be done. However, if θ _i and θ _f are increased, a high S / N can be obtained, but the substrate traveling speed at the time of film formation must be slowed down, and productivity is reduced.

An object of the present invention is to provide a method for solving the above-mentioned conventional problems and manufacturing a magnetic recording medium having high S / N with high productivity.

[0011]

According to the present invention, when a magnetic layer is formed on a moving substrate by a vacuum deposition method,
This is a method of manufacturing a magnetic recording medium in which two evaporation portions of one evaporation source are provided in the substrate traveling direction.

[0012]

According to the present invention, when the magnetic layer is formed on the moving substrate by the vacuum vapor deposition method, two evaporation portions of one evaporation source are provided in the substrate traveling direction, so that the shielding plates 3A and 3B are provided. Even if the opening between and is wider than before, the angle of incidence of vaporized atoms on the substrate can be increased, so that a magnetic recording medium having high S / N can be provided with high productivity.

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to the drawings showing its embodiments.

FIG. 1 shows an example of the inside of a vacuum vapor deposition apparatus for carrying out a method of manufacturing a magnetic recording medium according to an embodiment of the present invention. That is, the substrate 1 made of a polymer material is
It is wound around the supply roll 4, runs along the cylindrical can 2 in the direction of the arrow 6, and is wound up by the winding roll 5.

The evaporation source 8 has two evaporation portions 11 and 12 in the substrate traveling direction, from which evaporated atoms are evaporated. Here, the relationship between the position of the film forming portion and the position of the evaporation portion is not limited, and whatever the positional relationship is, the method of the present invention is higher than the conventional method. Although the present invention has high productivity and is of great value, it is particularly useful for the evaporation unit 1.
1 is located in the vicinity of the vertical line 13 passing through the film formation start portion,
Higher productivity can be expected by locating the evaporation part 12 near the vertical line 14 passing through the film formation end part. The vaporized atoms vaporized from these vaporization parts are shielded by the shield plates 3A and 3A.
It passes through the openings between B and adheres to the substrate 1. Shield plate 3
An oxygen inlet 10 for introducing oxygen into the vacuum chamber is arranged at the end of B. The evaporation source 8 is filled with the evaporation material 7.

By forming the magnetic layer while the substrate 1 is running with the above-described structure, θ _i and θ _f can be calculated as shown in FIG. 2 as compared with the case where the magnetic layer is manufactured by the conventional method shown in FIG.
By setting the same as in the above case, the width of the opening between the shielding plates 3A and 3B can be increased. It should be noted that FIG.
At, θ _i and θ _f are measured as follows. θ _i is the angle formed by the straight line connecting the center of the evaporation part 11 on the film formation start part side and the film formation start part, and the radius of the cylindrical can passing through the film formation start part, and θ _f is the film formation end part side. Is an angle formed by a straight line connecting the center of the evaporation portion 12 and the film formation end portion and the radius of the cylindrical can passing through the film formation end portion. It has been experimentally confirmed that the θ _i and θ _f measured in this manner are associated with the conventional θ _i and θ _{f of} FIG. That is, the magnetic layer produced by the vacuum vapor deposition apparatus having the configuration of FIG. 1 of the present invention and the magnetic layer produced by the conventional vacuum vapor deposition apparatus having the configuration of FIG. 2 have the same θ _i and θ _f , respectively. When set, they have almost the same magnetic characteristics and recording / reproducing characteristics.

In an actual production device, the width of the substrate is 50 cm or more. In this case, since the shape of the evaporation source viewed from above is generally a rectangle long in the direction perpendicular to the paper surface, the evaporation portions 11 and 12 may be extended in the direction perpendicular to the paper surface. That is, the evaporation units 11 and 12 may be extended in the width direction as shown by the dotted line in FIG. 3 which is a schematic perspective view of the evaporation source. Such a state of the evaporation portion can be easily realized by scanning the electron beam emitted from the electron gun. Note that when such a scan is performed with one electron gun, there is a region where the electron beam moves from the evaporation part 11 to 12 or from 12 to 11, but in order to prevent the influence of this region from occurring, , It is sufficient to perform a scan that makes this movement quick. In the present invention, this point is not taken into consideration because such scanning is actually performed.

The effect of the present invention is that the evaporators 11 and 12 are
Although it does not depend on the evaporation rate of atoms,
By making the evaporation rate of the evaporation section 11 on the film formation start side higher than that of the evaporation section 12 on the film formation end side,
S that is higher than that when the evaporation rate from both evaporation parts is the same
/ N is obtained. The reason for this is considered to be that the higher the film deposition rate at the film formation start portion, the higher the crystal orientation of the magnetic layer.

By the above-mentioned method, C is used as the vaporized substance.
o, Co-Ni, Co-Cr, Co-Ni-Cr, Co
By forming the magnetic layer using —Fe, Co—Ni—Fe, or the like, a magnetic tape having excellent recording / reproducing characteristics can be obtained with high productivity.

The above examples will be described below with reference to specific examples, and the recording / reproducing characteristics of the vapor deposition tape produced by the method of the present invention and the vapor deposition tape produced by the conventional method will be compared.

As a first embodiment of the present invention, a vapor deposition tape was produced using a vacuum vapor deposition apparatus having a basic structure as shown in FIG. The diameter of the cylindrical can 2 was 1.5 m, and a polyethylene terephthalate film having a tape thickness of 7 μm was used as the substrate 1. Co was used as the evaporation material 7. The distance between the evaporation parts 11 and 12 was 10 cm. θ _i is 8
The shielding plates 3A and 3B were set so that 2 ° and θ _f were 60 °. At this time, the width of the opening between the shielding plates 3A and 3B was 25 cm. With the above structure, a magnetic layer having a film thickness of 0.1 μm was formed with an average film deposition rate of 0.3 μm / s. Oxygen was introduced from the oxygen inlet 10 at a rate of 0.8 l / min. The traveling speed of the substrate during film formation is 45
It was m / min.

Next, as a second embodiment of the present invention, the magnetic layer was formed by setting the evaporation rate from the evaporation section 11 to 1.5 times the evaporation rate from the evaporation section 12. The conditions other than this evaporation rate were exactly the same as in the case of the first embodiment. The evaporation rate was controlled and adjusted so that the irradiation time of the electron beam from the electron gun was longer in the evaporation unit 11 than in the evaporation unit 12. The width of the opening between the shielding plates 3A and 3B was 25 cm. The traveling speed of the substrate during film formation was 45 m / min.

Next, as a comparative example, a magnetic layer was formed by a conventional method. The basic structure of the vacuum vapor deposition apparatus is the same as that in the case of FIG. 1 described above, except that the evaporation portion is provided at one location as shown in FIG. θ _i and θ _f were set to the same values as those in the above-mentioned embodiment, that is, θ _i = 82 ° and θ _f = 60 °. In order to do this, the width of the opening between the shielding plates 3A and 3B had to be 17 cm. With the above structure, a magnetic layer having a film thickness of 0.1 μm was formed with an average film deposition rate of 0.3 μm / s. Oxygen inlet 1
From 0, oxygen was introduced at a rate of 0.8 l / min. The traveling speed of the substrate at this time was 31 m / min, which was significantly slower than that of the examples of the present invention.

The medium produced as described above was slit into a tape shape, and the gap length of sendust was 0.15.
The recording / reproducing characteristics were evaluated using a ring type magnetic head of μm. As a result of the measurement, the reproduction output and noise of the magnetic tape manufactured by the conventional method and the magnetic tape manufactured by the first embodiment of the present invention showed almost the same value. Further, the magnetic tape manufactured in the second embodiment of the present invention had a reproduction output higher than that of the magnetic tape manufactured in the first embodiment of the present invention, and was +1.5 dB at a recording wavelength of 0.5 μm.

As described above, the magnetic tape manufactured by the method of the present invention has the same S as the magnetic tape manufactured by the conventional method.
Despite having / N, the film can be formed with significantly higher productivity than the conventional method.

Even if the length of the evaporation portion in the substrate traveling direction is increased by leaving the evaporation portion at one position as in the present invention instead of providing the evaporation portion at two positions as in the present invention, the opening between the shield plates 3A and 3B is formed. It is possible to widen the width of the part. However, in this case, when the electric power supplied to the electron gun is constant, the unit area of the evaporation unit and the electric power supplied per unit time are lower than those of the present invention. It will be lower than in the case of the invention.

It is also possible to arrange two evaporation sources side by side in the substrate running direction. However, judging from the physical size of the actual evaporation source, in such arrangement, the interval between the two evaporation portions is set to be small. It is difficult to reduce the width, and the effect of the present invention cannot be obtained.

In the above embodiment, the case where Co is used as the evaporating substance has been described, but the present invention is not limited to this, and Co-Ni, Co-Fe, Co-N can be used as the evaporating substance.
Even when i-Fe, Co-Cr, Co-Ni-Cr alloy or the like is used, the same effect of the present invention can be obtained.

Further, in the above embodiments, the polyethylene terephthalate film was used as the substrate for explanation, but the present invention is not limited to this, for example, a polymer film such as a polyimide film, a polyamide film, a polyetherimide film, a polyethylene naphthalate film, or the like. It goes without saying that the same applies to a polymer film having an underlayer.

Further, the incident angle of the vaporized atoms to the substrate, the interval between the vaporized portions, etc. are not limited to the values in the above embodiment.

[0031]

As is apparent from the above description,
The present invention has an advantage that a thin film magnetic recording medium having a high S / N can be manufactured with high productivity.

[Brief description of drawings]

FIG. 1 is a diagram showing an outline of the inside of a vacuum vapor deposition apparatus for carrying out a method of manufacturing a magnetic recording medium according to an embodiment of the present invention.

FIG. 2 is a diagram showing an outline of the inside of a conventional vacuum vapor deposition apparatus.

FIG. 3 is a schematic perspective view of an evaporation source for carrying out a method of manufacturing a magnetic recording medium according to an embodiment of the present invention.

[Explanation of symbols]

1 Substrate 2 Cylindrical can 3A, 3B Shielding plate 4 Supply roll 5 Winding roll 6 Substrate traveling direction 7 Evaporated material 8 Evaporation source 9 Evaporated atom 10 Oxygen inlet 11 Evaporation located near the vertical line passing through the film formation start part Part 12 Evaporation part located near the vertical line passing the film formation end part 13 Vertical line passing the film formation start part 14 Vertical line passing the film formation end part

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Kazuya Yoshimoto 1006 Kadoma, Kadoma City, Osaka Prefecture Matsushita Electric Industrial Co., Ltd.

Claims (3)

[Claims] 1. A method of manufacturing a magnetic recording medium, characterized in that, when a magnetic layer is formed on a moving substrate by a vacuum vapor deposition method, two evaporation portions of one evaporation source are provided in the traveling direction of the substrate. Method. 2. The magnetic recording medium according to claim 1, wherein the two evaporation portions are near a vertical line passing through the film formation start portion and near a vertical line passing through the film formation end portion. Method. 3. The method for producing a magnetic recording medium according to claim 1, wherein the evaporation rate in the evaporation section near the film formation start section is higher than the evaporation rate in the evaporation section far from the film formation start section.