JPH117627A - Magnetic recording medium and its method and device of manufacturing - Google Patents

Abstract

PROBLEM TO BE SOLVED: To manufacture with high production efficiency a vapor-deposited magnetic recording medium superior in electromagnetic transducing characteristic. SOLUTION: An oxygen content is controlled at the depth of 50 nm from the surface of the nonmagnetic supporting body of a magnetic layer. Additionally, in manufacturing a magnetic recording medium, in forming a vapor- deposited film by making a vapor flow evaporated from a vapor-depositing source 9 made incident on the surface of the nonmagnetic supporting body 5, which continuously runs along the outer circumference of a cylindrical can 6, an oxygen gas is supplied to such incident vapor flow from the introducing side of the nonmagnetic supporting body 5 by a first oxygen gas introducing pipe 14, and simultaneously the oxygen gas is also supplied from its delivering side by the second pipe 17.

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 magnetic recording medium in which a magnetic layer is formed by a vapor deposition method, and an apparatus for manufacturing a magnetic recording medium.

[0002]

2. Description of the Related Art For example, in the field of video tape recorders and the like, in recent years, there has been a strong demand for higher density recording in order to achieve higher image quality. As a corresponding magnetic recording medium, a metal magnetic material is applied directly to a non-magnetic support by plating or a vacuum thin film forming technique (vacuum deposition method, sputtering method, ion plating method, etc.) to form a magnetic layer. A so-called metal magnetic thin film type magnetic recording medium to be formed has been proposed.

[0003] This metal magnetic thin film type magnetic recording medium is not only excellent in coercive force, squareness ratio and electromagnetic conversion characteristics in a short wavelength region, but also enables thinning of a magnetic layer. Since there is no need to include a non-magnetic material such as a binder in a magnetic layer as in a medium, there are many advantages such as a high packing density of a magnetic material.

[0004] Above all, a vapor-deposited type magnetic tape (vapor-deposited tape) in which a magnetic layer is formed by a vacuum vapor deposition method has already been put into practical use because of its high production efficiency and stable characteristics.

In the above-mentioned vapor deposition tape, vapor deposition for forming a magnetic layer is performed by heating a cylindrical can for guiding a nonmagnetic support, a magnetic material as a vapor deposition source, and a vapor deposition source in a vacuum chamber. This is performed by a vapor deposition apparatus having a heating means or the like.

In such a vapor deposition apparatus, for example, a magnetic material mainly composed of Co is converted into a vapor flow by irradiation of an electron beam or the like, and is incident on a non-magnetic support running along the outer peripheral surface of the cylindrical can. A deposited film is formed.

[0007] The magnetic layer of the vapor-deposited tape is basically formed by the above method, but various improvements have been made to further improve the coercive force, the saturation magnetic flux density, and the like of the magnetic layer.

For example, in order to improve the coercive force, an oxygen gas introduction pipe having a slit-shaped outlet along the width direction of the non-magnetic support is used, and the steam flow is oxidized by the oxygen gas supplied through the oxygen gas introduction pipe. That is being done.

However, when the magnetic layer is oxidized, the coercive force can be increased, but since the oxide has a lower magnetic flux density than the non-oxidized magnetic material, this method can only improve the electromagnetic conversion characteristics to a certain extent. .

Also, attempts have been made to increase the output by forming a large number of vapor-deposited films having different growth directions and degrees of oxidation of metal particles.

However, in this method, the amount of the evaporation source used increases as much as the number of magnetic layers increases, and the process must be repeated for the number of layers.

Further, a method of forming a vapor deposition film only by a vapor flow incident at a specific incident angle has been proposed.
In this method, since a vapor flow other than the vapor flow incident at this incident angle is not used, the vapor deposition efficiency is low. In addition, there is a disadvantage that the vapor flow not used for forming the vapor-deposited film is wasted, and the amount of the vapor-deposition source is increased.

[0013]

As described above, various improvements have been made to the method of manufacturing a vapor-deposited tape so far, but the characteristics of the vapor-deposited tape cannot be sufficiently improved, and the production efficiency is not improved. Problems arise and require further consideration.

Therefore, the present invention has been proposed in view of such conventional circumstances, and a magnetic recording medium having good electromagnetic conversion characteristics and a magnetic recording medium having excellent electromagnetic conversion characteristics have been produced with high manufacturing efficiency. It is an object of the present invention to provide a magnetic recording medium manufacturing method and a magnetic recording medium manufacturing apparatus that can be manufactured.

[0015]

Means for Solving the Problems To achieve the above-mentioned object, a magnetic recording medium of the present invention comprises a magnetic layer containing Co formed on a non-magnetic support by an evaporation method.
The magnetic layer is characterized in that the oxygen content at a depth of 50 nm from the surface of the nonmagnetic support is 25 atomic% or more with respect to the Co content.

The method of manufacturing a magnetic recording medium according to the present invention is characterized in that the vapor flow evaporated from the vapor deposition source is incident on the surface of a non-magnetic support continuously running along the outer peripheral surface of the cylindrical can. Is formed by supplying oxygen gas to the vapor flow incident on the surface of the nonmagnetic support from both the introduction side and the delivery side of the nonmagnetic support.

The apparatus for manufacturing a magnetic recording medium according to the present invention comprises a cylindrical can for guiding a non-magnetic support, a vapor deposition source, and a first supply of oxygen gas to the vapor stream from the introduction side of the non-magnetic support.
And a second gas introduction pipe for supplying oxygen gas to the vapor flow from the delivery side of the non-magnetic support.

In a magnetic recording medium in which a magnetic layer is formed by a vapor deposition method, the oxygen content of the magnetic layer is regulated to 25 atomic% or more with respect to the Co content at a depth of 50 nm from the surface of the nonmagnetic support. In this case, a high coercive force can be obtained, and good electromagnetic conversion characteristics can be obtained.

Further, when forming a magnetic layer of a magnetic recording medium by a vapor deposition method, oxygen gas is supplied to the vapor flow incident on the surface of the nonmagnetic support from both the introduction side and the delivery side of the nonmagnetic support. A magnetic layer which is appropriately oxidized from the deep part to the surface part is formed. In this magnetic layer, the decrease in magnetic flux density due to oxidation is suppressed to a small value, and the coercive force is greatly increased. Therefore, good electromagnetic conversion characteristics can be obtained.

Further, in this case, the magnetic layer can be formed with a high vapor deposition efficiency as compared with the method using only the vapor flow incident at a specific incident angle, because the amount of the vapor deposition source used can be reduced.

[0021]

Embodiments of the present invention will be described below.

The magnetic recording medium of the present invention has a magnetic layer containing Co formed on a non-magnetic support by oblique deposition.

The above-mentioned magnetic layer has a thickness of 50 nm from the surface of the non-magnetic support.
The oxygen content at the thickness position of nm is 2 with respect to the Co content.
It is regulated to 5 atomic% or more. As described above, since the deep portion of the magnetic layer relatively close to the surface of the nonmagnetic support contains 25 atomic% or more of oxygen, a high coercive force can be obtained, and good electromagnetic conversion characteristics can be obtained.

In order to obtain better electromagnetic conversion characteristics, it is desirable that the oxygen content at a depth of 25 nm from the surface of the magnetic layer be 50 atomic% or less with respect to the Co content. If a highly oxidized surface oxide layer is formed on the surface of the magnetic layer, the oxide layer has a lower magnetic flux density than the non-oxidized magnetic material. Is impaired. In order to suppress the deterioration of the electromagnetic conversion characteristics due to such spacing, it is desirable that the oxygen content at a depth of 25 nm from the surface of the magnetic layer be suppressed to 50 atomic% or less.

Next, a method for manufacturing the magnetic recording medium of the present invention will be described.

In order to manufacture a magnetic recording medium by the manufacturing method of the present invention, first, a magnetic layer is formed on a non-magnetic support by a vapor deposition method. Here, in particular, in this manufacturing method, a magnetic recording medium having excellent electromagnetic conversion characteristics is manufactured by introducing oxygen gas into a vapor flow for vapor deposition from two directions.

FIG. 1 shows an example of a vapor deposition apparatus for forming this magnetic layer.

This vapor deposition apparatus vaporizes a metal magnetic material serving as a vapor deposition source, and forms a magnetic layer while introducing oxygen gas into the vapor flow.

In this vapor deposition apparatus, a supply roll 3 rotating in a clockwise direction in the figure and a winding roll rotating in a clockwise direction in the figure are placed in a vacuum chamber 2 in which a high vacuum state is created by an exhaust device 1. A take-up roll 4 is provided, and a non-magnetic support 5 is sequentially run from the supply roll 3 to the take-up roll 4 in a tape shape.

A cooling can 6 having a diameter larger than the diameter of each of the rolls 3 and 4 is provided in the middle of the travel of the non-magnetic support 5 from the supply roll 3 to the winding roll 4. I have. The cooling can 6 is provided so as to pull out the nonmagnetic support 5 to the right in the drawing.
It is configured to rotate at a constant speed in the clockwise direction in the figure. still,
The supply roll 3, the take-up roll 4, and the cooling can 6 each have a cylindrical shape having substantially the same length as the width of the non-magnetic support 5, and the cooling can 6 has no internal part therein. A cooling device is provided so that deformation and the like of the nonmagnetic support 5 due to a temperature rise can be suppressed. The temperature of the cooling can is set to, for example, about -25 ° C.

Further, between the supply roll 3 and the cooling can 6, and between the cooling can 6 and the take-up roll 4, rotating rolls 7 are provided, respectively. A predetermined tension is applied to the non-magnetic support 5 running sequentially over the winding roll 4 so that the non-magnetic support 5 runs smoothly.

A crucible 8 is provided in the vacuum chamber 2 obliquely below the cooling can 6 on the right side of the drawing, and a metal magnetic material is filled in the crucible 8 as an evaporation source 9. I have. The crucible 8 has substantially the same width as the width of the cooling can 6 in the longitudinal direction.

On the other hand, an electron gun 10 for heating and evaporating the evaporation source 9 filled in the crucible 8 is attached to the side wall of the vacuum chamber 2. This electron gun 10
The electron beam 11 emitted from the electron gun 10 is disposed at a position where the electron beam 11 is irradiated on the evaporation source 9 in the crucible 8.

In this vapor deposition apparatus, the non-magnetic support 5
A deposition plate 12 is provided to prevent the vapor flow deviating from the diffusion from diffusing and adhering to the inner wall of the vacuum chamber 2. The attachment-preventing plate 12 is formed by bending a plate having a width substantially equal to the width of the cooling can 6 into a substantially right angle,
One end faces the cooling can 6 and the other end faces the bottom side of the vacuum chamber 2 outside the crucible 8. Note that a slit 12a through which the electron beam 11 emitted from the electron gun 10 passes is provided in the deposition-preventing plate 12, and the electron beam 11 passes through the slit 12a and is irradiated on the evaporation source 9. I have.

A first oxygen gas introducing pipe 14 is attached to one end of the deposition-preventing plate 12 via an arm 13. The arm 13 has a length substantially equal to that of the first oxygen gas introduction pipe 14 and is formed in a hook shape in cross section as shown in FIGS.
Is attached. Also, the first oxygen gas introduction pipe 1
Reference numeral 5 denotes a cylindrical pipe having a length substantially equal to the width of the cooling can, and gas outlets are formed at regular intervals along the length direction. The gas outlets are provided at intervals of, for example, 0.5 mm in diameter and 20 mm, but are not limited thereto, and can be adjusted as appropriate.

The first oxygen gas introduction pipe 14 is attached to the arm 13 such that the gas outlet faces obliquely downward on the nonmagnetic support side. In the first oxygen gas introduction pipe 14 attached to the arm 13 as described above,
The space surrounded by the arm 13 and the side cover 15 functions as an oxygen chamber, and has a high oxygen partial pressure in this space.
Therefore, the steam flow can be easily oxidized by the oxygen gas blown out from the first oxygen gas introduction pipe 14. The direction in which oxygen gas is blown out from the gas blowout port of the first oxygen gas introduction pipe 14 is indicated by an arrow d in the figure.

Further, as shown in FIG. 1, near the cooling can 6 and closer to the delivery side of the nonmagnetic support 5 than the first oxygen gas introduction pipe 14, the nonmagnetic support 5
The shutter 16 is provided to cover the predetermined area, and is configured to block the vapor flow from adhering to an area other than the predetermined vapor deposition area.

A second oxygen gas introducing pipe 17 is attached to the tip of the shutter 16.
The second oxygen gas introducing pipe 17 is provided for the cooling can 6.
4 and has a prismatic outer shape as shown in FIG.
a is provided as a slit. The direction in which the oxygen gas is blown out from the gas outlet 17a of the second oxygen gas introducing pipe 17 is indicated by an arrow e in the figure.

In the above-described vapor deposition apparatus, as shown in FIG. 5, an electron beam 11 emitted from an electron gun 10 is incident on a point A on the surface of the vapor deposition source 9 to melt and vaporize the vapor deposition source 9. The evaporated vapor flow 18 is oxidized by the oxygen gas which rises and is blown out from the first oxygen gas introduction pipe 14 and the second oxygen gas introduction pipe 17, and travels at a constant speed on the outer peripheral surface of the cooling can 6. The light enters the support 5. On the non-magnetic support 5, a vapor layer 18 is deposited while continuously traveling, thereby forming a magnetic layer in which metal particles grow in an oblique direction.

Incidentally, in the oblique deposition in which the metal particles are grown in an oblique direction, the incident angle differs depending on the incident position of the vapor flow. Here, the incident angle of the steam flow is an angle between the normal line of the cooling can and the incident direction of the steam flow. The maximum incident angle of the steam flow in this case is the incident angle of the steam flow incident tangentially to the cooling can, and the normal OC at the incident position C of the steam flow incident tangentially.
And the angle α (that is, 90 °) formed by the tangent lines AC. On the other hand, the minimum incident angle of the vapor flow is the incident angle of the vapor flow incident on the deposition region D at the shortest distance, and the normal line OB at the incident position B of the vapor flow incident on the shortest distance and the incident position of the vapor flow. An angle β formed between B and a line AB connecting the point A on the evaporation source. The minimum incident angle β is desirably 40 to 55 °. The maximum incident angle α is controlled by the position of the vapor deposition source with respect to the cooling can, and the minimum incident angle β is controlled by the position of the vapor deposition source with respect to the cooling can, and the positions of the shutter 16 and the second oxygen gas supply pipe 17. be able to.

As described above, the vapor stream 18 incident on the surface of the non-magnetic support 5 has a maximum incident angle side (introduction side of the non-magnetic support).
When the oxygen gas is supplied from the minimum incident angle side (the sending side of the non-magnetic support), a magnetic layer which is appropriately oxidized from the deep part to the surface part is formed. In this magnetic layer, the decrease in magnetic flux density due to oxidation is suppressed to a small value, and the coercive force is greatly increased. Therefore, good electromagnetic conversion characteristics can be obtained.

In this case, the magnetic layer may be multi-layered,
Compared to the method of limiting the incident angle of the vapor flow to be deposited, the amount of the evaporation source used is small and the number of times of vapor deposition is only one, so that high production efficiency can be obtained.

In order to form a magnetic layer having an excellent output and a high C / N ratio, the first oxygen gas introduction pipe 14 is required.
Position, the gas blowing direction of the second oxygen gas introducing pipe 17 and the slit width are important.

First, the introduction of oxygen gas through the first oxygen gas introduction pipe 14 contributes to increasing the degree of oxidation in a relatively deep portion of the deposited film (near the surface of the nonmagnetic support).

The first oxygen gas introducing pipe 14 has a gap f between 1 and 15 mm between the first oxygen gas introducing pipe 14 and the cooling can 6 shown in FIG.
It is desirable that When the gap f between the first oxygen gas introduction pipe 14 and the cooling can 6 is smaller than 1 mm,
Since the first oxygen gas introducing pipe 14 and the non-magnetic support 5 are close to each other, they may come into contact with each other, causing inconvenience in the apparatus configuration. If the gap between the first oxygen gas introducing pipe 14 and the cooling can 6 exceeds 15 mm, the steam flow 18 cannot be sufficiently oxidized.

On the other hand, the introduction of oxygen gas from the second oxygen gas introduction pipe 17 is more effective than the introduction of oxygen gas from the first oxygen gas introduction pipe 14 to increase the degree of oxidation in a relatively deep portion of the deposited film. To increase the degree of oxidation in shallower portions.

The direction in which the oxygen gas is blown out from the second oxygen gas introduction pipe 17 should be 65 to 115 ° with respect to the incident direction of the steam flow incident at the maximum incident angle shown in FIG. preferable. If the angle θ is smaller than 65 °, the steam hits the gas outlet of the second oxygen gas introducing pipe 17, and the deposit accumulates around the outlet over time. As a result, blowing from the gas blowing port cannot be performed uniformly, and film formation becomes unstable. Also, the second
The vapor flow is disturbed by the oxygen gas blown out from the oxidizing gas introduction pipe 17, whereby the film structure of the deposited film (columnar structure)
And the squareness ratio is reduced.

When the angle θ is larger than 115 °, a thick surface oxide layer having a high oxidation degree is formed on the surface of the magnetic layer. Since the surface oxide layer has a lower saturation magnetic flux density than a non-oxidized magnetic material, if the surface oxide layer is thicker, it causes magnetic spacing between the surface oxide layer and the magnetic head, and the electromagnetic conversion characteristics are impaired.

The gas outlet 17a of the second oxygen gas introducing pipe 17 has a slit width g shown in FIG.
It is preferably 0.0 mm. Slit width g is 1.0
If it is less than mm, the magnetic layer cannot be sufficiently oxidized, and the coercive force Hc decreases. Also, the slit width g is 1
If the thickness exceeds 0.0 mm, the oxidation proceeds too much, which adversely affects the electromagnetic conversion characteristics.

The above is an example of the vapor deposition apparatus, and various modifications can be made to this vapor deposition apparatus. For example, in this example, the shutter and the second oxygen gas introduction pipe are provided as separate components, but they may be the same member. Further, the second oxygen gas introducing pipe may be attached to the side surface of the shutter on the cylindrical can side, or may be attached to the back surface thereof.

Further, although an electron beam is used here as a heat source for heating the evaporation source, other heaters such as a high-frequency induction heating source can be used.

As the evaporation source and the non-magnetic support, any of those commonly used in evaporation type magnetic recording media can be used.

As a ferromagnetic metal material serving as a deposition source, F
e, metal such as Co, Ni, Co-Ni alloy, Co-P
t-based alloy, Co-Pt-Ni-based alloy, Fe-Co-based alloy, Fe-Ni-based alloy, Fe-Co-Ni-based alloy, Fe
-Ni-B alloy, Fe-Co-B alloy, Fe-Co
-Ni-B-based alloys and Co-Cr-based alloys.

As the nonmagnetic support, polyesters such as polyethylene terephthalate, polyethylene,
Polyolefins such as polypropylene, cellulose derivatives such as cellulose triacetate, cellulose diacetate, and cellulose acetate butyrate, vinyl resins such as polyvinyl chloride and polyvinylidene chloride, and plastics such as polycarbonate, polyimide, polyamide, and polyamideimide are used. .

Although the magnetic recording medium manufactured in this manner can obtain sufficiently good electromagnetic conversion characteristics even when the magnetic layer is a single layer, it is possible to form a large number of magnetic layers by changing the deposition conditions. By doing so, a higher output and a higher C / N ratio can be exhibited.

[0056]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below based on experimental results.

In this embodiment, when forming the magnetic layer using Co as the vapor deposition source, the supply conditions of the oxygen gas from the first oxygen gas introduction pipe and the second oxygen gas introduction pipe are changed, and the optimum condition is obtained. The conditions were examined. The maximum incident angle α is 90
゜, the minimum incident angle was set to 50 °.

The maximum incident angle side by the first oxygen gas introducing tube
Examination of supply of oxygen gas from the furnace The oxygen gas flow rate from the second oxygen gas introduction pipe was set to 2600 c
c / min, and changing the flow rate of the oxygen gas from the first oxygen gas inlet pipe to 0 cc / min, 400 cc / min, and 1000 cc / min to form a 200 nm-thick magnetic layer and produce various sample tapes. did. The slit width of the second oxidizing gas introduction pipe was 1.0 mm, and the angle θ in the blowing direction was 8 mm.
0 °.

FIG. 6 shows the composition of oxygen and cobalt in the thickness direction of the three sample tapes measured by electron spectroscopy.

As shown in FIG. 6, when the oxidation is performed by the first oxygen gas introduction tube, the deep portion of the magnetic layer is particularly harder than when the oxidation is not performed by the first oxygen gas introduction tube. (150 to 200 nm), the oxygen concentration increases. Then, while the coercive force of the magnetic layer formed without performing oxidation by the first oxygen gas introduction pipe is 97 kA / m, 400 cc
The coercive force of the magnetic layer oxidized at a flow rate of 115 kA / m
It is. From this, it was found that the supply of oxygen gas through the first oxygen gas introduction pipe was effective in increasing the coercive force of the magnetic layer.

Next, the magnetic layer was formed by fixing the oxygen gas flow rate from the first oxygen gas introduction pipe to 400 cc / min and the oxygen gas flow rate from the second oxygen gas introduction pipe to 2600 cc / min. A tape was made. Note that the thickness of the magnetic layer was changed in a range of 170 nm or more. For comparison, various magnetic layers having different thicknesses were formed without performing oxidation using the first oxygen gas inlet tube, and sample tapes were produced.

The output and C / N ratio of the produced sample tape were measured. In addition, output and C / N
The conditions for measuring the ratio are as follows.

Measurement method: Electromagnetic conversion characteristics by rotating head Tape running speed Vt: 10 m / sec Track width Tw: 13.0 μm Recording frequency f: 20 MHz Recording wavelength λ: 0.5 μm Magnetic head gap width: 0.22 μm Magnetic layer FIG. 7 shows the relationship between the thickness of the magnetic layer and the output.
FIG. 8 shows the relationship between the / N ratio. Note that the output and the C / N ratio are shown as relative values with respect to the case where the thickness of the magnetic layer is 190 nm or 180 nm without introducing oxygen gas from the first oxygen gas introduction pipe.

As can be seen from FIG. 7 and FIG. 8, the sample tape oxidized by the first oxygen
A larger output can be obtained as compared with a sample tape which is not oxidized by the oxygen gas inlet tube.

Also, the C / N ratio of the sample tape oxidized by the first oxygen gas inlet tube is larger than that of the sample tape not oxidized by the first oxygen gas inlet tube. .

Thus, the oxygen gas is supplied from the minimum incident angle side by the second oxygen gas introducing pipe, and the oxygen gas is supplied from the maximum incident angle side by the first oxygen gas introducing pipe. It has been found that the electromagnetic conversion characteristics can be improved.

Is the second oxygen gas inlet tube at the low incidence angle side?
Examination of oxygen gas supply from the first oxygen gas inlet pipe to 400 cc
/ Min, the oxygen gas flow rate from the second oxygen gas introduction pipe is 26
The sample was fixed at 00 cc / min to form a magnetic layer to produce a sample tape. The slit width of the oxygen outlet of the second oxygen gas introducing pipe was 0.9 mm or 1.2 mm. The angle θ of the blowing direction of the second oxidizing gas introduction pipe is 80 °.

FIG. 9 shows the oxygen concentration profiles of these two types of sample tapes in the thickness direction by electron spectroscopy. The oxygen concentration is a percentage of the oxygen content to the cobalt content.

As shown in FIG. 9, the sample tape in which the slit width of the second oxygen gas introduction pipe was 1.2 mm was smaller than the sample tape in which the slit width of the second oxygen gas introduction pipe was 0.9 mm. Thus, the oxygen concentration increases in the depth range of 100 to 180 nm. From this, it was found that the supply of oxygen gas by the second oxygen gas introduction pipe affects the oxygen concentration in the shallower portion of the magnetic layer than the supply of oxygen gas by the first oxygen gas introduction pipe. . In the example where the slit width is 1.2 mm, the oxygen content at a depth of 50 nm from the surface of the non-magnetic support is C
o at least 25 atomic% with respect to the content,
The oxygen content at a depth of nm is 5
It was confirmed that the content was 0 atomic% or less.

Next, the slit width of the second oxygen gas introducing pipe is further increased by 0.9 mm, 1.0 mm, 1.1 mm, 1.
A sample tape was prepared by changing the thickness to 2 mm, and the coercive force and the output were measured. FIG. 1 shows the relationship between the slit width and the coercive force Hc.
FIG. 11 shows the relationship between the slit width and the output.

As shown in FIGS. 10 and 11, the coercive force Hc
And the output both increase as the slit width of the second oxygen gas introducing pipe increases. Here, in a magnetic tape for performing high-density recording, the coercive force Hc needs to be 100 kA / m or more, and such characteristics can be obtained only when the slit width of the second oxygen gas introduction pipe is 1.0 mm. The above is the case.

From this, it was found that the slit width of the second oxygen gas introducing pipe was desirably 1.0 mm or more. However, if the slit width of the second oxygen gas introduction pipe exceeds 3.0 mm, the proportion of non-magnetic cobalt oxide becomes too large and adversely affects the electromagnetic conversion characteristics. It is desirable to set the range to 0 mm.

The magnetic layer was formed by fixing the flow rate of oxygen gas from the first oxygen gas introduction pipe at 400 cc / min and the flow rate of oxygen gas from the second oxygen gas introduction pipe at 2600 cc / min.
A sample tape was prepared. The angle θ in the gas blowing direction of the second oxygen gas introduction pipe was set to 85 ° or 120 °. The slit width of the second oxidizing gas introduction pipe is 1.0 mm.

FIG. 12 shows the oxygen concentration profiles in the thickness direction of these two types of sample tapes. The oxygen concentration is a percentage of the oxygen content to the cobalt content.

As shown in FIG. 12, in any of the sample tapes, a region (surface oxide layer) having an oxygen concentration of 40 atomic% or more is formed in the vicinity of the surface of the magnetic layer. In the case where the angle θ in the gas blowing direction of the oxygen gas introduction pipe of No. 2 is 85 ° (about 20 nm), the angle θ
Is set to 120 ° (about 30 nm).

This indicates that the thickness of the surface oxide layer can be controlled by regulating the gas blowing direction of the second oxygen gas introducing pipe. Here, the surface oxide layer is
Since it is almost non-magnetic and has magnetic spacing with the magnetic head, it is necessary to keep the thickness below a certain value. For that purpose, the angle θ of the blowing direction of the second oxygen gas introducing pipe needs to be 65 to 115 °.

[0077]

As is clear from the above description, in the magnetic recording medium of the present invention, the oxygen content at a depth of 50 nm from the surface of the nonmagnetic support of the magnetic layer is more than the Co content. Since it is regulated to 25 atomic% or more, good electromagnetic conversion characteristics can be obtained.

Further, in the present invention, in producing a magnetic recording medium, when a vapor deposition film is formed on the surface of a continuously running non-magnetic support, a vapor flow incident on the surface of the non-magnetic support is applied to the non-magnetic support. Since oxygen gas is supplied from both the introduction side and the delivery side, it is possible to obtain a magnetic recording medium having excellent electromagnetic conversion characteristics.

Further, in this case, as compared with the method using only the vapor stream incident at a specific incident angle, the vapor deposition efficiency can be increased without using a small amount of vapor deposition source, and high production efficiency can be obtained.

[Brief description of the drawings]

FIG. 1 is a schematic view showing an example of a vapor deposition apparatus for performing a manufacturing method of the present invention.

FIG. 2 is a schematic perspective view of a main part showing a first oxygen gas introduction pipe provided in a vapor deposition apparatus.

FIG. 3 is a sectional view of a first oxygen gas introduction pipe.

FIG. 4 is a schematic perspective view of a main part showing a second oxygen gas introduction pipe provided in the vapor deposition apparatus.

FIG. 5 is a schematic diagram for explaining an incident angle of a steam flow and a blowing direction of a second oxygen gas introduction pipe.

FIG. 6 is a characteristic diagram showing a composition profile of oxygen and cobalt in a thickness direction of the magnetic layer with respect to a magnetic layer in which a gas flow rate of a first oxygen gas introduction pipe is changed.

FIG. 7 is a characteristic diagram showing a relationship between a magnetic layer thickness and an output.

FIG. 8 is a characteristic diagram illustrating a relationship between a film thickness of a magnetic layer and a C / N ratio.

FIG. 9 is a characteristic diagram showing an oxygen concentration profile in the thickness direction of the magnetic layer for the magnetic layer in which the slit width of the second oxygen gas introducing pipe is changed.

FIG. 10 is a characteristic diagram showing a relationship between a slit width and a coercive force of a second oxygen gas introduction pipe.

FIG. 11 is a characteristic diagram showing a relationship between a slit width of a second oxygen gas introduction pipe and an output. ,

FIG. 12 is a characteristic diagram showing an oxygen concentration profile in a thickness direction of a magnetic layer for magnetic layers having different gas blowing directions of a second oxygen gas introduction pipe.

[Explanation of symbols]

6 cylindrical can, 9 evaporation source, 14 first oxygen gas introduction pipe, 17 second oxygen gas introduction pipe

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[Procedure amendment]

[Submission date] July 23, 1997

[Procedure amendment 1]

[Document name to be amended] Statement

[Correction target item name] 0072

[Correction method] Change

[Correction contents]

From this, it was found that the slit width of the second oxygen gas introducing pipe was desirably 1.0 mm or more. However, the slit width of the second oxygen gas introduction pipe is 1
If the thickness exceeds 0.0 mm, the ratio of nonmagnetic cobalt oxide becomes too large, which adversely affects the electromagnetic conversion characteristics.

Claims (11)

[Claims] 1. Coating a non-magnetic support on a non-magnetic support by vapor deposition.
Wherein the oxygen content of the magnetic layer at a depth of 50 nm from the surface of the nonmagnetic support is 25 atomic% or more with respect to the Co content. Magnetic recording medium. 2. The method according to claim 1, wherein the magnetic layer has a thickness of 25 nm from the surface of the magnetic layer.
2. The magnetic recording medium according to claim 1, wherein the oxygen content at the depth position is 50 atomic% or less with respect to the Co content. 3. A vapor stream evaporated from an evaporation source,
When forming a vapor-deposited film by making it incident on the surface of the non-magnetic support running continuously along the outer peripheral surface of the cylindrical can, the vapor flow incident on the surface of the non-magnetic support is introduced into the non-magnetic support introduction side and the delivery side. A method for manufacturing a magnetic recording medium, wherein oxygen gas is supplied from both sides of the magnetic recording medium. 4. The method for manufacturing a magnetic recording medium according to claim 3, wherein the incident direction of the vapor flow incident on the introduction side of the non-magnetic support substantially coincides with the tangential direction of the cylindrical can. 5. The blowing direction of oxygen gas supplied from the delivery side of the non-magnetic support is set at an angle of 65 ° to 115 ° with respect to the incident direction of the steam flow incident in the tangential direction of the cylindrical can. 5. The method for manufacturing a magnetic recording medium according to claim 4, wherein: 6. A cylindrical can for guiding the non-magnetic support, a vapor deposition source, a first gas introduction pipe for supplying oxygen gas to the vapor flow from the introduction side of the non-magnetic support, and delivery of the non-magnetic support to the vapor flow. And a second gas inlet pipe for supplying oxygen gas from the side. 7. The apparatus for manufacturing a magnetic recording medium according to claim 6, wherein an incident direction of the vapor flow incident on the introduction side of the nonmagnetic support substantially coincides with a tangential direction of the cylindrical can. 8. The blowing direction of oxygen gas supplied from the delivery side of the nonmagnetic support is at an angle of 65 ° to 115 ° with respect to the incident direction of the steam flow incident tangentially to the cylindrical can. The apparatus for manufacturing a magnetic recording medium according to claim 7, wherein 9. The method according to claim 1, wherein the first gas introduction pipe is attached to an arm, and the arm functions as an oxygen chamber for increasing a partial pressure of oxygen gas blown out from the first oxygen gas introduction pipe. Item 7. An apparatus for manufacturing a magnetic recording medium according to Item 6. 10. A shutter is provided on the delivery side of the non-magnetic support relative to the deposition region on the non-magnetic support, and a second oxygen gas introduction pipe is provided at the tip of the shutter. The apparatus for manufacturing a magnetic recording medium according to claim 6. 11. The apparatus according to claim 6, wherein the width of the gas outlet of the second oxygen gas introducing pipe is 1.0 to 10.0 mm.