JPH09198655A - Production of magnetic recording medium - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a process for producing a thin-film type magnetic recording medium having a high S/N with high productivity. SOLUTION: This recording medium is constituted by evaporating a material 7 to be evaporated which consists of Co from an evaporating source 8 by an electron beam vacuum vapor deposition method while supplying oxygen from an oxygen supplying port 10 onto a substrate 1 consisting of a polyethylene terephthalate film traveling in an arrow 6 direction along a cylindrical can 2 and forming a Co-based magnetic layer contg. oxygen on the substrate 1 by adhesion of the evaporated particles 9 on the substrate. A heating element 16 consisting esentially at least one kind selected from between Mo and W is arranged to face the substrate between a part 11 where the formation of the magnetic layer begins and a part 12 where the formation of the magnetic layer ends. The magnetic layer is formed while the components consisting essentially of at least one kind selected from between Mo and W generated from this heating element 16 is simultaneously adhered thereto.

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 there is a demand for magnetic recording media having excellent recording / reproducing characteristics particularly in the short wavelength region. Thin film magnetic recording media have been developed to meet this demand. The thin film magnetic recording medium is manufactured by a vacuum deposition method, a sputtering method, a plating method, or the like, and has a recording density higher than that of a so-called coating type magnetic recording medium in which a magnetic layer is formed by coating a mixture of magnetic powder and a resin binder on a substrate. And has excellent recording / reproducing characteristics in the short wavelength region. Examples of the magnetic layer in the thin film magnetic recording medium include Co, Co-Ni, Co-Ni-P, and Co.
-O, Co-Ni-O, Co-Cr, Co-Ni-C
A magnetic layer containing Co as a main component such as r, Co-Cr-Ta, and Co-Cr-Pt (usually referred to as a Co-based magnetic layer) generally has excellent recording / reproducing characteristics and practical characteristics. Has been done.

An example of a conventional method for manufacturing a thin film magnetic recording medium by a conventional vacuum evaporation method will be described with reference to FIG.
FIG. 4 shows an example of the internal structure of a conventional vacuum vapor deposition apparatus for producing a thin film magnetic recording medium. 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,
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 it is extremely advantageous to evaporate a refractory metal such as Co at a high evaporation rate.

A shield plate 3 is provided in a part of the circumference of the cylindrical can 2 to prevent unnecessary evaporated atoms 9 from adhering to the substrate 1. The magnetic layer is formed between the magnetic layer formation start portion 11 and the magnetic layer formation end portion 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 straight line connecting the magnetic layer formation end portion 12 and the evaporation portion 15.
In the case of the electron beam evaporation source, evaporation of the evaporation material mainly occurs from the portion irradiated with the electron beam, so the evaporation unit 15
Is the part irradiated by the electron beam.

An oxygen supply port 10 for supplying oxygen into the vacuum chamber at the time of vapor deposition is provided at the end of the shield plate 3.
The amount of oxygen supply is optimized and Co or Co-
When a Co-based alloy such as Ni is used, the coercive force of the formed magnetic layer can be increased, and the recording / reproducing characteristics and the practical characteristics are excellent.
A thin film magnetic recording medium comprising a Co-based magnetic layer containing oxygen can be 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.

[0006]

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

When the Co—O type magnetic layer is formed by the vacuum deposition method as shown in FIG.
It is known that the coercive force is improved and the S / N is improved by using a multilayer structure having a layer structure or more. This is 1
In the case of a layer, the magnetic layer is magnetically continuous in the easy axis direction of the magnetic layer, but when two or more layers are formed, magnetic continuity is lost at the interface of the layers, and the magnetic unit is small. Therefore, it is estimated that the coercive force is improved and the S / N is improved. In short, it seems that finer magnets constitute the magnetic layer.

By the way, in the conventional method as shown in FIG. 4, for example, when the magnetic layer is made to have a two-layer structure, the substrate is run once to form the first magnetic layer, and then the substrate is rewound. Once again, the substrate on which the first magnetic layer is formed must be run to deposit the second magnetic layer. Therefore, the multi-layer structure of the magnetic layer means that S
Although this leads to an improvement in / N, it causes a problem that productivity is reduced. Even more, if a multi-layered structure having three or more layers is used, a magnetic recording medium having more excellent coercive force and S / N can be obtained, but the cost is extremely increased due to the problem of productivity.

An object of the present invention is to solve the above problems and to provide a method for producing a magnetic recording medium having high productivity, large coercive force and high S / N.

[0010]

In order to solve the above-mentioned problems, in the method of manufacturing a magnetic recording medium of the present invention, a Co-based magnetic layer containing oxygen is formed on a moving substrate by a vacuum deposition method. At this time, a heating element containing at least one selected from Mo and W as a main component is arranged facing the substrate between the magnetic layer formation start portion and the magnetic layer formation end portion, and the Mo generated from this heating element is arranged. Alternatively, the magnetic layer is formed while simultaneously adhering at least one component selected from W as a main component.

By adopting the above means, a layer containing Mo or W or Mo and W is formed in the magnetic layer film. In the layer containing Mo or W or Mo and W, the saturation magnetization is lowered, so that the magnetic layers are magnetically separated above and below this layer, and a characteristic close to a two-layer structure is obtained.
That is, since the magnetic layer having a structure separated into two layers can be formed by running the substrate once, the thin film magnetic recording having a large coercive force and an improved S / N without lowering the productivity as compared with the prior art. It becomes possible to manufacture a medium.

In the method for producing a magnetic recording medium of the present invention, it is preferable to form a layer containing a large amount of at least one selected from Mo and W in the magnetic layer. Since Mo or W has the property of a non-magnetic material, by forming a layer containing a large amount of these, the magnetic layers are magnetically separated above and below this layer, and the characteristics closer to the two-layer structure can be obtained as described above. And preferred.

Further, in the method of manufacturing the magnetic recording medium of the present invention, it is preferable that the temperature of the heating element is equal to or higher than the melting point of Co. This is preferable because Co is less likely to adhere to the heating element and more stable production is possible.

In the magnetic recording medium manufacturing method of the present invention, it is preferable that the temperature of the heating element is 1800 ° C. or higher. By doing so, a large number of Mo atoms or W atoms or Mo atoms and W atoms can be generated from the heating element, which is preferable.

Further, in the method of manufacturing a magnetic recording medium of the present invention, it is preferable that the heating element is a heating element whose cross-sectional shape is concave toward the substrate. By making the cross-sectional shape of the heating element concave toward the substrate, it is possible to prevent the vapor of at least one type of Mo or W generated from the heating element from being widely diffused and becoming diluted, and it is relatively high in bulk. Since it can be attached at a density, the attached Mo
Alternatively, at least one W atom can be increased, which is preferable.

Further, in the method for manufacturing a magnetic recording medium of the present invention, oxygen is supplied from the vicinity of the magnetic layer formation end portion toward the magnetic layer formation portion side, and the heating element is arranged at a position exposed to this oxygen. However, Mo atoms and W generated from the heating element
This is preferable because the amount of atoms increases.

Further, in the method of manufacturing a magnetic recording medium of the present invention, a plurality of heating elements are arranged, so that a more multilayered structure can be realized, and the coercive force and S / N of the magnetic layer can be further improved. It is possible and preferable.

Further, in the method of manufacturing a magnetic recording medium of the present invention, the magnetic layer has a coercive force of the magnetic layer in which the easy axis of magnetization is inclined with respect to the normal to the substrate surface. Can be made larger, which is preferable.

[0019]

BEST MODE FOR CARRYING OUT THE INVENTION A Co-based magnetic layer formed in the present invention is a magnetic layer containing Co as a main component of a metal element, and Co is 60 atomic% or more of the metal elements contained in the magnetic layer. Preferably, more preferably 7
It is 0 atomic% or more.

Specifically, Co, Co-Ni, Co-N
i-P, Co-O, Co-Ni-O, Co-Cr, Co
A magnetic layer containing Co such as —Ni—Cr, Co—Cr—Ta, and Co—Cr—Pt as a main component can be given. In the method of the present invention, a magnetic metal is vapor-deposited while supplying oxygen as described later, but preferably about 5 to 70 atomic% of the metal elements of the vapor-deposited magnetic layer, more preferably 10 to It is preferable to supply oxygen so that about 60 atomic% becomes a metal oxide.
Since the metal element and the metal oxide are present in the magnetic layer in this way, the magnetic units having a magnetism are in a state of being dispersed in finer units, so that the magnetic layer having a higher coercive force is obtained. Are estimated to be formed.

An embodiment of the present invention will be described below with reference to the drawings. 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. Basically, it is the same as the conventional example of FIG. 4, except that the heating element 16 is arranged. The heating element 16 is mainly composed of Mo or W or Mo and W, and is arranged between the magnetic layer formation start portion 11 and the magnetic layer formation end portion 12 so as to face the substrate 1. The heating element is heated by resistance heating by passing an electric current. When the substrate 1 is supplied from the magnetic layer formation start portion 11 toward the magnetic layer formation end portion 12, vaporized atoms 9 composed of Co-based vaporized from the evaporation source 8 are attached onto the substrate 1. Heating element 1
By arranging 6 in the position as shown in FIG.
In the upper part of 6, the Mo atoms or W atoms or the Mo atoms and W atoms generated from the heating element 16 themselves are attached to the magnetic layer attached on the substrate 1. Further, since the vaporized atoms 9 vaporized from the vaporization source 8 are shielded by the heating element 16, Co atoms do not adhere much to the magnetic layer on the substrate 1 above the heating element. As a result, above the heating element 16, a Mo atom or a W atom or a layer containing a large amount of Mo and W atoms is formed on the magnetic layer on the substrate 1. Then, the substrate 1 is further moved in the direction of the magnetic layer formation end portion 12, so that the Co component is again adhered on this. Since the formed layer containing a large amount of Mo atoms or W atoms or Mo and W atoms has a low saturation magnetization, the magnetic layers are magnetically separated above and below this layer, and the magnetic layer has a two-layer structure. To have characteristics. Heating element 1
The closer 6 is to the substrate 1, the more densely Mo atoms or W atoms or Mo and W atoms can be attached to the magnetic layer on the substrate 1, and a layer containing a large amount is formed. When the heating element 16 is moved away from the substrate 1, the generated Mo atoms or W atoms or Mo and W atoms are
As it is diffused and the density becomes thin, if necessary, the heating element 1
The distance between 6 and the substrate 1 may be adjusted so that Mo atoms or W atoms having a desired density or Mo atoms and W atoms are attached. In particular, when a layer containing a large amount of at least one selected from Mo and W is formed in the magnetic layer, the size of the apparatus, the size and shape of the heating element 16, the heating temperature, the traveling speed of the substrate 1, and the like. Since the conditions are completely different depending on the conditions, etc., it is not possible to unconditionally define, but the distance between the heating element 16 and the cylindrical can 2 is cylindrical on a straight line connecting the center of the cylindrical can 2 and the heating element 16. The distance between the surface of the can 2 and the heating element 16 may be set to about 15 cm or less, and an appropriate distance may be selected according to the above conditions.

The heating element 16 is preferably heated to a melting point of 1495 ° C. or higher of Co, which is the main element of the evaporation material, so that Co can be prevented from adhering to the heating element. Stable production is possible. Further, in order to generate a large amount of Mo atoms, W atoms, or Mo atoms and W atoms from the heating element 16, it is desirable that the temperature of the heating element is high. It is preferably 1800 ° C. or higher and the melting point or lower. However, if the temperature is set too high, the life of the heating element will be shortened and the influence of heat radiation on the substrate will increase. Therefore, the temperature may be set in consideration of these. In addition, in an actual production apparatus, the substrate 1 is generally used.
Width is over 50 cm. In this case, the evaporation source 8 usually has a shape long in the direction perpendicular to the paper surface of FIG. 1, and the heating element 16 also uses a linear shape long in the direction perpendicular to the paper surface of FIG.

Although the cross-sectional shape of the heating element 16 is not limited, it is possible to increase the number of Mo atoms or W atoms or Mo atoms and W atoms attached to the magnetic layer on the substrate 1 by making the heating element 16 concave toward the substrate 1. You can An example of the shape of such a heating element is shown at 16 'in FIG. FIG. 3 is a partial schematic view of the vicinity of a heating element inside the vacuum vapor deposition apparatus. Heating element 1
By making the cross-sectional shape of 6 ′ concave as shown in FIG. 3, it is possible to prevent wide diffusion of Mo atoms or W atoms or Mo atoms and W atoms generated from the heating element 16 ′. It is preferable because the density of vapor of generated Mo atoms or W atoms or vapor of Mo atoms and W atoms can be increased, and the rate of attachment to the magnetic layer on the substrate 1 can be increased.

As for the positional relationship between the oxygen supply port 10 and the heating element 16, as shown in FIG. 1, oxygen is blown out from the vicinity of the magnetic layer formation end portion 12 toward the magnetic layer formation portion side and exposed to this oxygen. It is desirable to dispose the heating element 16 in a position where The reason for this is preferable because it is experimentally confirmed that the mechanism can increase the amounts of Mo atoms and W atoms generated from the heating element 16, although the mechanism is not clear.

As described above, according to one embodiment of the present invention, a magnetic layer having a two-layer structure can be formed by running the substrate once, so that the productivity can be reduced as compared with the conventional case. / N can be improved.

When the magnetic layer is formed in the positional relationship between the substrate and the evaporation source as shown in FIG. 1, evaporated atoms are obliquely incident on the substrate. When the magnetic layer is formed by such oblique incidence, the easy axis of magnetization is oriented obliquely to the normal to the film surface. The present invention is particularly effective for such a magnetic layer in which the easy axis of magnetization is oblique to the normal line of the magnetic layer film surface. As described above, when forming the magnetic layer in which the easy axis of magnetization is oriented obliquely to the normal line of the magnetic layer film surface, although not particularly limited, the vaporized atoms 9 in the magnetic layer formation end portion 12 are formed. The angle of incidence on the substrate (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 in FIG. 1) is preferably in the range of 30 ° or more.

Next, another embodiment of the present invention will be described with reference to FIG. 2 is basically the same as FIG. 1, but
This is different from the case of FIG. 1 in that two heating elements 16 and 17 are arranged instead of one heating element. When the magnetic layer is formed in this way, the magnetic layer is formed for the same reason as in FIG.
A magnetic layer having a layer structure is obtained. This makes it possible to further improve the coercive force and S / N of the magnetic layer. A magnetic layer having a four-layer structure or more can be obtained by increasing the number of heating elements as in the above description.

[0028]

EXAMPLES The examples described in the above embodiments will be described below with reference to specific examples, and the magnetic characteristics of the magnetic recording medium manufactured by the method of the present invention and the magnetic recording medium manufactured by the conventional method will be described. And, the recording and reproducing characteristics are compared.

Example 1 As a first specific example of the present invention, a magnetic recording medium was manufactured using a vacuum vapor deposition apparatus having a basic structure as shown in FIG. The cylindrical can 2 had a diameter of 1 m, and a polyethylene terephthalate film having a thickness of 6 μm was used as the substrate 1. Co was used as the evaporation material 7. As the heating element 16, Mo having a diameter of 6 mm is used.
As shown in FIG. 1, a line was used and it was arranged at a distance of 4 cm (the definition of the distance was as described above) from the surface of the cylindrical can 2 while facing the substrate 1. A current was passed through the heating element 16 to raise the temperature to about 2000 ° C. Substrate 1
Width is 50 cm. Angle of incidence of vaporized atoms on the substrate at the magnetic layer formation end portion (in FIG. 1, a straight line connecting the center of the cylindrical can 2 to the magnetic layer formation end portion 12 and a straight line 14).
The position of the shielding plate 3 was set so that the acute angle formed by and was 40 °. A magnetic layer having a film thickness of 0.15 μm was formed with the above-described structure. 0.8l / min from the oxygen supply port 10
Oxygen was supplied at a rate of. The evaluation results of the obtained magnetic recording medium are shown in Table 1.

(Embodiment 2) Next, as a second specific embodiment of the present invention, as shown in FIG.
7 was arranged, and otherwise the same as in Example 1 to form a magnetic layer having a film thickness of 0.15 μm. The evaluation results of the obtained magnetic recording medium are shown in Table 1.

Comparative Example 1 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 that shown in FIG. 1 except that the heating element 16 is not provided, and is as shown in FIG. With such a structure, a magnetic layer having a film thickness of 0.15 μm was formed under the same conditions as in Example 1 above. The evaluation results of the obtained magnetic recording medium are shown in Table 1.

The magnetic characteristics and recording / reproducing characteristics of the medium manufactured as described above are evaluated by measuring the hysteresis curve in the longitudinal direction with a vibrating sample magnetometer and determining the coercive force from this. evaluated. Here, the longitudinal direction is the substrate traveling direction during vapor deposition.
The recording / reproducing characteristics were evaluated by slitting the magnetic recording medium into a tape shape and using a ring type magnetic head made of sendust and having a gap length of 0.2 μm. Table 1 shows the measurement results. Table 1 shows coercive force and S / N. The S / N is evaluated by recording / reproducing a signal having a recording wavelength of 0.5 μm, and the medium of Comparative Example 1 is shown as 0 dB.
Compared with the magnetic recording medium of Comparative Example 1 manufactured by the conventional method,
The magnetic recording media produced in the examples of the present invention have high coercive force and S / N.

As described above, the magnetic recording medium produced by the method of the present invention has a higher S / N than the magnetic recording medium produced by the conventional method, but the productivity is higher than that of the conventional method. Is equivalent to.

[0034]

[Table 1]

In the above specific embodiment, C is used as the evaporation material.
Although the case of using o has been described, the present invention is not limited to this, and Co-Ni, Co-Fe, and C are used as evaporation materials.
Even when an o-Ni-Fe alloy or the like is used, the same effect of the present invention can be obtained. Further, the film thickness of the magnetic layer and the incident angle of the vaporized atoms to the substrate are not limited, and it is needless to say that the magnetic layer can be applied to the magnetic layer whose easy axis of magnetization is oriented in the normal direction of the substrate 1. . The material, shape and temperature of the heating element are not limited to the specific examples.

Further, in the above-mentioned specific examples, the example in which the polyethylene terephthalate film is used as the substrate has been described, but the present invention is not limited to this, and for example, a polyimide film, a polyamide film, a polyetherimide film, a polyethylene naphthalate film or the like can be used. It goes without saying that the same applies to a molecular film or a polymer film having some layer formed. Moreover, the film thickness of the substrate is not limited.

[0037]

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 vacuum vapor deposition apparatus for carrying out the method of manufacturing a magnetic recording medium of one embodiment according to the invention.

FIG. 3 is a partial schematic view in the vicinity of a heating element inside a vacuum vapor deposition device for showing an example of a cross-sectional shape of the heating element used in the present invention.

FIG. 4 is a diagram showing an outline of the inside of a vacuum evaporation apparatus for carrying out a method of manufacturing a magnetic recording medium according to a conventional method.

[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 Evaporation parts 16, 16 ', 17 Heating elements

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Claims (8)

[Claims] 1. An oxygen-containing C on a moving substrate.
When an o-based magnetic layer is formed by a vacuum deposition method, at least one selected from Mo and W as a main component is located between the magnetic layer formation start portion and the magnetic layer formation end portion, facing the substrate. A method of manufacturing a magnetic recording medium, wherein a heating element is arranged and a magnetic layer is formed while simultaneously adhering at least one component selected from Mo and W generated from the heating element as a main component. 2. The method for producing a magnetic recording medium according to claim 1, wherein a layer containing a large amount of at least one selected from Mo and W is formed in the magnetic layer. 3. The method for manufacturing a magnetic recording medium according to claim 1, wherein the temperature of the heating element is set to the melting point of Co or higher. 4. The method for producing a magnetic recording medium according to claim 1, wherein the temperature of the heating element is 1800 ° C. or higher. 5. The method for manufacturing a magnetic recording medium according to claim 1, wherein the heating element is a heating element whose cross-sectional shape is concave toward the substrate. 6. The magnetic recording according to claim 1, wherein oxygen is supplied from the vicinity of the magnetic layer formation end portion toward the magnetic layer formation portion, and the heating element is arranged at a position exposed to the oxygen. Medium manufacturing method. 7. A plurality of heating elements are arranged.
7. The method for manufacturing a magnetic recording medium according to any one of 6 above. 8. The method for manufacturing a magnetic recording medium according to claim 1, wherein the magnetic layer is a magnetic layer whose easy axis of magnetization is inclined with respect to a normal line of the substrate surface.