JPH08221753A - Production of magnetic recording medium - Google Patents

Abstract

PURPOSE: To obtain a thin-film type magnetic recording medium having high S/N with high productivity by providing the side of a part where the formation of magnetic layers is started with a sheet heated up to the m.p. of a material to be evaporated nearly opposite to a substrate. CONSTITUTION: The sheet 19 heated up to the m.p. of the material 7 to be evaporated is arranged nearly opposite to the traveling substrate 1 on the side of the part where the formation of magnetic layers is started at the time of forming the magnetic layers by a vacuum vapor deposition method on the travelling substrate 1. A first magnetic layer forming part 18 having diagonal magnetic anisotropy is formed by the evaporated atoms reflected by the sheet 19 and a second magnetic layer forming part 17 having the diagonal magnetic anisotropy is formed in succession thereon by the evaporated atoms flying directly from an evaporating source 8 is formed thereon. As the result, the evaporated atoms failing to be adhered when the sheet 19 is not installed like heretofore are reflected by the sheet 19 and fly to adhere diagonally at the substrate 1 thereby, the first magnetic layer forming part 18 is formed, and in succession, the conventional second magnetic layer forming part 17 is formed. Thus, the thin-film type magnetic magnetic tape having the improved S/N is produced with the high productivity.

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 has been increasing year by year, and thin-film magnetic recording media having excellent short-wavelength recording / reproducing characteristics have been developed. As the magnetic layer in the thin film magnetic recording medium, for example, Co, Co-Ni, Co-Ni-P,
Co-O, Co-Ni-O, Co-Cr, Co-Ni-
Cr, Co-Cr-Ta, Co-Cr-Pt, etc. have been 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-deposited 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 for manufacturing a vapor deposition tape for a VTR for 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 material 7 adhere to the substrate 1 to form a magnetic layer. An electron beam evaporation source is suitable as the evaporation source 8, and the evaporation material 7 is filled with an alloy such as Co or Co—Ni. 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.

In order to prevent unnecessary vaporized atoms 9 from adhering to the substrate 1, a part of the circumference of the cylindrical can 2 is covered with a shield plate 3.
Is provided. The magnetic layer is formed in the magnetic layer forming part 16 between the magnetic layer forming start part 11 and the magnetic layer forming end part 12. Reference numeral 13 is a straight line connecting the magnetic layer formation start portion 11 and the evaporation portion 15, and 14 is a magnetic layer formation end portion 12 and the evaporation portion 1.
It is a straight line connecting 5 and. In the case of an electron beam evaporation source, evaporation of the evaporation material mainly occurs from the part irradiated with the electron beam, so the evaporation part 15 is the part irradiated with the electron beam.

An oxygen supply port 10 for introducing oxygen into the vacuum chamber at the time of vapor deposition is provided at the end of the shield plate 3. By optimizing the oxygen supply amount, 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.

[0007]

[Problems to be Solved by the Invention] In the future, with high productivity,
A thin film magnetic tape having a high S / N in the short wavelength region is required.

When a Co—O type magnetic layer is formed by the vacuum deposition method as shown in FIG. 2, the coercive force is improved by increasing the incident angle of vaporized atoms to the substrate, and the S / N ratio is increased.
Are known to be improved. Here, the angle of incidence of vaporized atoms on the substrate is the angle formed by the direction of incidence of vaporized atoms on the substrate and the normal to the substrate. However, when the magnetic layer is formed by the method as shown in FIG. 2, if the incident angle is increased, the width of the magnetic layer forming portion 16 becomes narrow, and the attachment efficiency of vaporized atoms is reduced. Therefore, although increasing the incident angle leads to an improvement in S / N,
Therefore, there arises a problem that productivity is reduced.

An object of the present invention is to solve the above problems and to provide a method of manufacturing a magnetic recording medium having a high S / N ratio with high productivity.

[0010]

According to the present invention, when a magnetic layer is formed on a moving substrate by a vacuum deposition method,
A thin plate whose temperature is equal to or higher than the melting point of the evaporation material is arranged on the magnetic layer formation start portion side so as to face the substrate, and a first magnetic layer having oblique magnetic anisotropy is formed by the evaporated atoms reflected by the thin plate. A method of manufacturing a magnetic recording medium, which comprises forming a second magnetic layer having oblique magnetic anisotropy by continuously forming vaporized atoms directly flying from an evaporation source.

[0011]

By adopting the above means, the vaporized atoms that did not adhere to the substrate without the thin plate are reflected by the thin plate and fly obliquely to the substrate to adhere. The attached vaporized atoms become a first magnetic layer having an oblique magnetic anisotropy. After the first magnetic layer is formed in this manner, the second magnetic layer is formed in the area where the conventional magnetic layer was formed, as in the conventional case. Therefore, it becomes possible to manufacture a thin film magnetic tape having an improved S / N with high productivity.

[0012]

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. The substrate 1 made of a polymer material 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.
In addition, in FIG. 1 and FIGS. 3 to 5 described later, the vaporized atoms 9 are not shown in order to avoid complication of the drawing.

The vaporized atoms evaporated from the evaporation portion 15 in the evaporation source 8 not only directly adhere to the substrate in the second magnetic layer forming portion 17, but also the first magnetic element before the second magnetic layer forming portion 17.
Also in the magnetic layer forming portion 18, the thin plate 19 reflects and adheres to the substrate 1. The thin plate 19 is disposed on the magnetic layer formation start portion side so as to face the substrate 1 and has a temperature higher than the melting point of the evaporation material 7.

The thin plate 19 may be made of tungsten, tantalum, molybdenum, carbon or the like, but according to the experiments conducted by the present inventors, carbon was most suitable. The reason is that it is difficult for carbon to react with the evaporation material,
It is difficult to deform even if the temperature is raised. In actual production equipment, the width of the substrate is generally 50 cm or more. In this case, the evaporation source 8 is usually long in the direction perpendicular to the paper surface, and the thin plate 19 is also long in the direction perpendicular to the paper surface.

Although the means for raising the temperature of the thin plate 19 is not limited, resistance heating in which a current is directly applied to the thin plate 19 to heat it is the easiest. The temperature of the thin plate 19 may be any temperature at which vaporized atoms reach the thin plate 19 and are reflected without being attached. Generally, if the temperature is raised above the melting point of the vaporized atoms, the vaporized atoms will hardly adhere. In order to completely eliminate the attachment of vaporized atoms, the higher the temperature, the better. However, it is necessary to determine the temperature in consideration of the difficulty of raising the temperature and the life of the thin plate 19.

According to the manufacturing method of the present invention shown in FIG. 1, in order to form the first magnetic layer having the oblique magnetic anisotropy in the first magnetic layer forming portion 18, the evaporated atoms are reflected and directed toward the substrate 1. Although a thin plate 19 for arranging in a diagonal direction is arranged, it is significantly different from the conventional manufacturing method shown in FIG. The operation of the thin plate 19 will be described below.

Among the vaporized atoms vaporized from the vaporization section 15 of the vaporization source 8, the flying direction A of the vaporized atoms indicated by a straight line 20.
Then, the vaporized atoms between the vapor atom flying direction B indicated by the straight line 22 reach the thin plate 19 and are reflected. The flying direction of the vaporized atoms reflected is random when the incident angle to the thin plate 19 is small, but when the incident angle is large, the incident angle and the reflection angle tend to be close to each other. Here, the reflection angle is an angle with respect to the normal line of the thin plate in the flying direction of the reflected vaporized atoms. Therefore, the vaporized atoms reflected by the thin plate 19 are mainly located between the flying direction A of the reflected vaporized atoms shown by the straight line 21 and the flying direction B of the reflected vaporized atoms shown by the straight line 23. , Is obliquely incident on the substrate 1. In this way, the first magnetic layer formed by the first magnetic layer forming portion 18 becomes an oblique magnetic anisotropic film. A second magnetic layer is further formed on the first magnetic layer by the second magnetic layer forming portion 17.

As described above, in the method of the present invention, the magnetic layer having the oblique magnetic anisotropy is formed within the range of the first magnetic layer forming portion 18 and the second magnetic layer forming portion 17. . On the other hand, in the conventional method, the magnetic layer is formed only in the area of the second magnetic layer forming portion 17. Therefore, according to the method of the present invention, the efficiency of attachment of vaporized atoms is improved as compared with the conventional method, so that it is possible to produce a magnetic tape having a high S / N with higher productivity than the conventional method.

In order to obtain excellent recording / reproducing characteristics, the first magnetic layer formed by being reflected by the thin plate 19 needs to have oblique magnetic anisotropy,
Moreover, it is preferable that the inclination angle of the easy axis of magnetization with respect to the film normal is as large as possible. Therefore, the thin plate 19 needs to be arranged so that the incident angle of the vaporized atoms reflected by the thin plate 19 on the substrate 1 is as large as possible.

Next, another embodiment of the present invention will be described with reference to FIG. FIG. 3 is basically the same as FIG. 1, but the vaporized atom flow is formed between the vapor flow for forming the first magnetic layer and the vapor flow for forming the second magnetic layer. This is different from the case of FIG. 1 in that a shielding plate 24 for shielding the is provided. By doing so, a region in which the amount of vaporized atoms attached is small or small is generated between the first magnetic layer forming portion and the second magnetic layer forming portion. As a result, the separation between the first magnetic layer and the second magnetic layer becomes clear, and the coercive force and S / N of the magnetic layer can be further improved. It is particularly effective in reducing noise.

Further, as shown in FIG. 4, an oxygen supply port 25 is arranged in the vicinity of the first magnetic layer formation end portion, and from there, the first
By supplying oxygen toward the magnetic layer forming part of
It is possible to further increase the magnetic separation between the first magnetic layer and the second magnetic layer, and further improvement in S / N can be expected.

Further, as shown in FIG. 5, before the thin plate 19 for forming the first magnetic layer, a thin plate for forming an underlayer having a temperature higher than the melting point of the evaporation material for forming the underlayer is further formed. If S and N are arranged substantially opposite to the substrate 1 and the underlayer is formed by the evaporated atoms reflected by the underlayer-forming thin plate 26, the S / N can be further improved. At this time, in the region 28 where the underlayer is formed, the oxygen supply port 2
It is necessary to supply oxygen from 7. Reference numerals 29 and 30 denote shield plates for preventing unnecessary evaporated atoms from adhering to the substrate.

The reason why the S / N can be improved by doing so will be described below. Co by vacuum deposition
When a -O-based magnetic layer is formed, when a Co-O-based magnetic layer is deposited on a Co-O-based non-magnetic or magnetic underlayer, the coercive force is improved and the S / N is improved. It has been clarified by the study of the present inventors. The region 2 where the underlayer is formed when manufactured as shown in FIG.
8 forms a Co—O based non-magnetic or magnetic underlayer, so that the first magnetic layer formed thereon has a higher coercive force than the case without the underlayer, and S / Further improvement of N becomes possible.

When the underlayer is formed as shown in FIG. 5, it is not necessary to run the substrate one more time to form the underlayer, so that the S / N ratio is reduced without lowering the productivity. Further improvements are possible.

The above examples will be described below with reference to specific examples, and the magnetic characteristics and 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 is 1 m and the thickness is 6
A μm polyethylene terephthalate film was used as the substrate 1. Co was used as the evaporation material 7. The thin plate 19 is a carbon plate having a height of 20 cm, a width (length in the direction perpendicular to the paper surface in FIG. 1) of 60 cm, and a film thickness of 1 mm, and is arranged so as to face the substrate 1 as shown in FIG. By applying an electric current to the thin plate 19, the temperature was raised to about 2000 ° C. The width of the substrate is 50 cm. The incident angle of vaporized atoms on the substrate at the magnetic layer formation end portion (in FIG. 1, the acute angle formed by the straight line connecting the center of the cylindrical can 2 and the magnetic layer formation end portion 12 and the straight line 14) is 60 °. The position of the shielding plate 3 was set as described above. With the above configuration, the film thickness is 0.1 μm
The magnetic layer of was formed. From the oxygen supply port 10, 1.5l /
Oxygen was supplied at a rate of min. The substrate traveling speed at this time was 80 m / min.

Next, as a second embodiment of the present invention, FIG.
A shield plate 24 is arranged between the first magnetic layer forming part and the second magnetic layer forming part as shown in FIG. Was formed. The substrate traveling speed at this time was 80 m / min. The second
In the embodiment and the third and fourth embodiments described later,
Since the vaporized atoms are shielded by the shield plate 24, if the substrate traveling speed is the same as that in the first embodiment, the film thickness becomes slightly thin. However, since the magnetic properties are improved,
There is no deterioration in the recording / reproducing characteristics due to the reduced film thickness.

As a third embodiment of the present invention, an oxygen supply port 25 is arranged as shown in FIG. 4, from which oxygen 0.9 l /
min was supplied, and otherwise the same as in Example 2 to form a magnetic layer having a thickness of 0.09 μm. The substrate traveling speed at this time was 80 m / min.

Next, as a fourth embodiment of the present invention, FIG.
As shown in FIG. 3, a thin layer 26 for forming an underlayer is further arranged in front of the thin plate 19, thereby forming an underlayer, and the first and second magnetic layers are formed thereon. Underlayer forming thin plate 26
Used the same size and material as the thin plate 19.
The temperature of the underlayer forming thin plate 26 was set to about 2000 ° C. The thickness of the underlayer is 0.01 μm, and the total thickness of the first and second magnetic layers is 0.09 μm. The oxygen supply port 2
Oxygen was supplied from No. 7 at a rate of 0.3 l / min, and otherwise the same as in the first embodiment. The traveling speed of the substrate is 80m /
It was min.

Next, as a comparative example, a magnetic layer was formed by a conventional method. The structure of the vacuum vapor deposition apparatus is the same as in the case of FIG. 1 except that the thin plate 19 is not provided. With such a structure, a magnetic layer having a film thickness of 0.1 μm was formed under the same conditions as in the first embodiment. However, the traveling speed of the substrate at this time was 50 m / min.

The magnetic characteristics and recording / reproducing characteristics of the medium manufactured as described above were evaluated. The magnetic characteristics were evaluated by measuring the hysteresis curve in the longitudinal direction with a vibrating sample magnetometer and determining the coercive force from this. Here, the longitudinal direction is the substrate traveling direction during vapor deposition. The recording / reproducing characteristics were evaluated by slitting the medium in a tape shape and using a ring type magnetic head made of sendust and having a gap length of 0.15 μm. The measurement results (Table 1)
Shown in Table 1 shows the substrate traveling speed, coercive force, and
The playback output and noise are shown. The reproduction output is a value when a signal with a recording wavelength of 0.5 μm is recorded and reproduced, and noise is a wavelength of 0.6 when a signal with a recording wavelength of 0.5 μm is recorded and reproduced.
The frequency value corresponding to μm is 0 dB for the tape of the comparative example.
It is shown as.

[0033]

[Table 1]

Compared with the magnetic tape of the comparative example produced by the conventional method, the magnetic tape produced in the first embodiment of the present invention has the same coercive force and recording / reproducing characteristics, but the substrate running speed during vapor deposition. Is 1.6 times, which means that the productivity is significantly improved.

The magnetic tape manufactured in the second embodiment of the present invention has a higher coercive force and noise of 1 dB lower than that of the magnetic tape manufactured in the first embodiment of the present invention. Moreover, the substrate traveling speed during vapor deposition is 1.6 times that of the conventional example. This improvement in the magnetic characteristics and the recording / reproducing characteristics is achieved by providing a region between the first magnetic layer forming portion and the second magnetic layer forming portion where vaporized atoms hardly adhere to the first magnetic layer. It is considered that this is because the separation of the second magnetic layer became clear.

The magnetic tape manufactured in the third embodiment of the present invention has a higher coercive force and a higher reproduction output than the magnetic tape manufactured in the second embodiment of the present invention. This cause is the first
It is considered that the magnetic separation of the magnetic layer and the second magnetic layer is further advanced than that of the second embodiment. The substrate traveling speed during vapor deposition is 1.6 times that of the conventional example.

The magnetic tape manufactured in the fourth embodiment of the present invention has higher coercive force and reproduction output and lower noise than the magnetic tape manufactured in the third embodiment of the present invention. This is because the magnetic characteristics of the first magnetic layer are improved by forming the underlayer. In this case, the substrate traveling speed during vapor deposition is 1.6 times that of the conventional example.

As described above, the magnetic tape manufactured by the method of the present invention can secure higher productivity than the magnetic tape manufactured by the conventional method, and can also improve the S / N.

In the above embodiments, the case where Co is used as the evaporation material has been described, but the invention is not limited to this, and Co-Ni, Co-Fe, Co-N can be used as the evaporation material.
Even when an i-Fe alloy or the like is used, the same effect of the present invention can be obtained. Also, the film thickness of the magnetic layer is not limited.

Further, in the above-mentioned embodiment, the polyethylene terephthalate film is used as the substrate, but the substrate 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, or It goes without saying that the same applies to a polymer film on which some layer is formed. Moreover, the film thickness of the substrate is not limited.

Further, the incident angle of vaporized atoms to the substrate, the thin plate, the material, size and shape of the underlayer forming thin plate are not limited to those in the above embodiment. For example, the shape of the thin plate may not be rectangular. Further, the shape viewed from the side is not a linear shape as shown in FIGS. 1 and 3 to 5,
It may be bent.

[0042]

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

FIG. 4 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. 5 is a diagram showing an outline of the inside of a vacuum vapor deposition apparatus for carrying out the method of manufacturing a magnetic recording medium of one embodiment according to the invention.

[Explanation of symbols]

 1 Substrate 2 Cylindrical can 3 Shielding plate 4 Supply roll 5 Winding roll 6 Substrate traveling direction 7 Evaporation material 8 Evaporation source 9 Evaporation atom 10 Oxygen supply port 11 Magnetic layer formation start part 12 Magnetic layer formation end part 13 Magnetic layer formation start A straight line connecting the magnetic field and the evaporation part 14 A straight line connecting the magnetic layer formation end part and the evaporation part 15 An evaporation part 16 A magnetic layer formation part 17 A second magnetic layer formation part 18 A first magnetic layer formation part 19 A thin plate 20 Evaporated atoms Direction of arrival A 21 direction of arrival of reflected vaporized atoms A 22 direction of arrival of vaporized atoms B 23 direction of arrival of reflected vaporized atoms B 24 shield plate 25 oxygen supply port 26 underlayer forming thin plate 27 oxygen supply port 28 bottom Formation layer 29, 30 Shielding plate

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

Claims (4)

[Claims] 1. When a magnetic layer is formed on a moving substrate by a vacuum vapor deposition method, a thin plate heated to a temperature equal to or higher than the melting point of an evaporation material is disposed on the magnetic layer formation start portion side so as to substantially face the substrate. Then, the first magnetic layer having oblique magnetic anisotropy is formed by the evaporated atoms reflected by the thin plate, and the first magnetic layer having oblique magnetic anisotropy is continuously formed thereon by the evaporated atoms directly flying from the evaporation source. 2. A method of manufacturing a magnetic recording medium, which comprises forming the second magnetic layer. 2. The method of manufacturing a magnetic recording medium according to claim 1, wherein a shield plate is arranged between the first magnetic layer forming portion and the second magnetic layer forming portion. 3. Oxygen is supplied from the first magnetic layer formation end portion side toward the first magnetic layer formation portion, and from the second magnetic layer formation end portion side toward the second magnetic layer formation portion. The method for manufacturing a magnetic recording medium according to claim 2, wherein oxygen is supplied. 4. A thin plate for forming a base layer, which has been heated to a temperature equal to or higher than the melting point of the evaporation material, is arranged in front of the thin plate so as to face the substrate, and is reflected by the thin plate for forming the base layer. 4. Oxygen is supplied to the region where the underlying layer is formed by vaporized atoms.
A method of manufacturing a magnetic recording medium according to item.