JPH0760522B2 - Method of manufacturing perpendicular magnetic recording medium - Google Patents

Description

The present invention relates to a method for manufacturing a perpendicular magnetic recording medium, and more particularly to a method for manufacturing a perpendicular magnetic recording medium with improved running durability.

[Conventional technology]

In recent years, a perpendicular magnetization recording method using a magnetic recording medium having an easy axis of magnetization in a direction perpendicular to the film surface of the recording medium has been proposed. In this perpendicular magnetization recording method, the demagnetizing field in the recording medium decreases as the recording density increases, so that excellent reproduction output can be obtained, and it can be said that this method is suitable for high density recording at an essentially lower level.

In order to perform the magnetic recording of the perpendicular magnetization recording system, a magnetic recording medium having an easy axis of magnetization in a direction perpendicular to the film surface of the recording medium is required. As such a perpendicular magnetic recording medium, there is known one in which a Co—Cr alloy or the like is formed by a sputtering method or the like on a substrate or a support made of a polymer material or a nonmagnetic material such as a nonmagnetic metal.

Further, in order to improve the recording / reproducing efficiency at the time of perpendicular magnetic recording / reproducing, a high magnetic permeability layer made of a soft magnetic material as an underlayer under the perpendicular magnetic recording layer made of the Co—Cr alloy film, for example, Permalloy ( A so-called double-layer film type perpendicular magnetic recording medium provided with a Ni-Fe alloy film is known.

Further, in a flexible disk or the like using the perpendicular magnetization recording system, a so-called double-sided double-layered perpendicular magnetic recording medium in which the double-layered perpendicular magnetic recording medium is formed on both surfaces of a support has a larger recording capacity. It is excellent because it is easy to improve curl.

Both types of perpendicular magnetic media are produced by applying the material to a support either continuously or discontinuously using a sputtering device.

[Problems to be solved by the invention]

Such a perpendicular magnetic medium is expected to be a magnetic tape or a magnetic disk as a recording medium suitable for high density recording.
One of the major problems is that the running durability is generally extremely poor, and for example, in the case of a perpendicular magnetic recording disk provided with a Co-Cr alloy film, the alloy layer on the surface is scraped after about 100 running passes, making it impossible to run. There are many.

In order to solve such problems, carbon, SiO ₂ , BN
(JP-A-58-133627), SiC (JP-A-58-130437) and the like have been proposed to be provided as a protective layer on the surface of the magnetic layer by sputtering or the like.

However, even with these treatments, the improvement of running durability is still insufficient, and even in the same manufacturing process, the reproducibility of the product is poor, and good durability and extremely poor durability are obtained. Then, there was a problem that a durable product could not be obtained.

Accordingly, the present invention is to provide a perpendicular magnetic recording medium having good reproducibility and significantly improved running durability, and a method for manufacturing the same.

[Means for solving problems]

The present invention, as a result of repeated studies to solve the above problems,
The inventors have found that a perpendicular magnetic recording medium having remarkably improved durability can be obtained with good reproducibility by providing a protective layer after forming an oxide layer or a nitride layer on the surface of the magnetic layer, and accomplished the present invention.

That is, the present invention provides a method for manufacturing a perpendicular magnetic recording medium in which a magnetic layer having perpendicular magnetic anisotropy and a protective layer are provided on at least one surface of a non-magnetic substrate by sputtering, after the magnetic layer is provided, a cylindrical can is formed. Of the target is subjected to sputtering (reverse sputtering) with a negative polarity of (-) to oxidize or nitrid the surface of the magnetic layer and then to provide a protective layer. Is the way.

Hereinafter, the present invention will be described in detail.

In the present invention, first, a so-called thin film forming method such as sputtering, vacuum deposition, ion plating, or the like on a non-magnetic substrate is provided with a perpendicularly magnetized film having an easy axis of magnetization in a direction perpendicular to the film surface on one or both sides, for example, Co-Cr film To form. In this case, a soft magnetic film having a low coercive force or a high magnetic permeability, for example, a permalloy film may be similarly provided by sputtering or the like before forming the perpendicular magnetization film. Further, the perpendicularly magnetized film or the like may be a single layer or a plurality of layers. A nonmagnetic underlayer may be provided between the substrate and the perpendicular magnetic layer, or a nonmagnetic intermediate layer may be provided between the soft magnetic layer and the perpendicular magnetic layer. Therefore, the magnetic layer referred to in the present invention includes the case where only the perpendicular magnetic film as described above is provided and the case where the soft magnetic film and the perpendicular magnetic film are provided.

As the non-magnetic substrate in the present invention, polyethylene terephthalate (PET), polyimide, has a particularly remarkable effect on film-like polymer materials such as polyamide,
It is also applicable to metallic materials, non-metallic materials such as glass, and the like.

Materials for the soft magnetic film include Ni-Fe, Ni-Fe-Mo, Ni-Fe-Mo-
Not limited to permalloy alloys such as Cu, Fe, Fe-Al-Si, Fe-Ni-
O, Fe-Ti, Ni-Fe-Cu-Cr-Mn, Fe-Si-B, Fe-BC, Fe-Al,
Co-V-Fe, Co-Ta, Co-Zr, Co-Nb-Zr, Co-Ti, Co-Nb-Ta,
So-called soft magnetic alloy materials such as Co-Ni-Zr, Fe-Ni-P, Fe-Co-Zr, Co-Mo-Zr are also applicable.

The film thickness is preferably 0.03 to 5 μm, particularly preferably 0.1 to 1 μm.

The perpendicular magnetization film needs to have the easy axis of magnetization in a direction substantially perpendicular to the surface of the support, and is an alloy material containing Co and Cr as main components, which is known as a material for the perpendicular magnetization film. Is desirable.

The film thickness is selected to be about 0.03 to 5 microns, but
05 to 1 micron is especially desirable.

As the film forming means, vapor deposition, sputter, etc. are used, but a so-called continuous sputter method having a plurality of high speed sputter sources arranged around a plurality of cylindrical cans as described in the examples below is preferable.

As the sputter source, for example, in the case of a Co—Cr alloy, a Co—Cr alloy may be used as a target, or Co and Cr may be used as different targets.

The temperature of the cylindrical can is preferably 30 ° C. or higher in order to prevent magnetic anisotropy in the plane of the soft magnetic film when forming a hard magnetic film such as a permalloy film. Alternatively, the above-mentioned permalloy film has a multi-layered structure, a part of which is formed at room temperature or below, and the remaining part is formed.
You may form at 100-150 degreeC. On the other hand, if the Kyan temperature is too high, gas will be released from the support and oligomers will be precipitated.

On the other hand, at the time of forming the Co-Cr film, it is desirable to heat the temperature of the cylindrical can to 90 ° C. or more in order to obtain the desired Hc (perpendicular), and to obtain the Hc (perpendicular) perpendicular magnetization film, 120 ° C or higher is particularly desirable.

The present invention is characterized in that the surface of the magnetic layer formed as described above is subjected to an oxidation treatment or a nitriding treatment and then a protective layer is provided.

The oxidation treatment or the nitriding treatment is performed by glow discharge treatment (about 500 V in O ₂ or N ₂ 10 ^-1 to 10 ^-4 Torr) in the presence of oxygen or nitrogen, or reverse sputtering in the presence of oxygen or nitrogen. Alternatively, oxygen ions or nitrogen ions may be implanted into the surface of the magnetic layer using an ion gun. In the case of sputtering, a magnetic layer (target-) is provided by sputtering, the polarity is reversed, and oxygen or nitrogen is added.
Reverse sputtering may be performed by applying a voltage in an atmosphere of 10 ^-1 to 10 ^-4 Torr.

In this way, a protective layer is provided next to the surface of the magnetic layer having the oxide layer or the nitride layer formed thereon by sputtering or the like.

As the protective layer, _{carbon, MoS 2, SiO, SiO 2} , Co-O
-Cr, Cr-O, etc. are used. Of these, carbon is particularly preferable.

The thickness of the protective layer is 0.002 μm to 0.1 μm, especially 0.005 μm.
~ 0.05 is preferred.

According to the present invention, a perpendicular magnetic recording medium having remarkably improved running durability can be obtained with good reproducibility.

〔Example〕

FIG. 1 is a schematic view showing an example of a sputter device used for producing the perpendicular magnetic recording medium of the present invention.

A double-sided double-layered perpendicular magnetization medium was prepared by using the double-sided continuous sputter device shown in FIG. A 50-micron-thick roll-shaped polyimide film 41 was set on a delivery shaft 42, and was wound around a winding shaft 45 via an intermediate roller and cylindrical cans 43 and 44. The vacuum chamber has a delivery chamber 46 and a sputter chamber 4
7. The winding chamber 48 is roughly divided into three, each chamber is partitioned by partition walls 49, 50, and each chamber is exhausted by exhaust systems 51, 52 and 53, 54, respectively. The DC planar magnetron type sputter cathodes 55, 57 having carbon and the RF planar magnetron type sputter cathodes 56, 58 having Co-Cr targets (Co82-Cr 18 wt%) were provided in the sputter chamber.

The sputter chamber 47 of the sputter device is set to 1 × 10 ^-6 to
The can was heated and maintained at 150 ° C. up to a pressure of rr or less, Ar gas was introduced from the gas introduction system 59, and maintained at about 5 × 10 ⁻³ torr. On the polyimide film 41 delivered from the delivery shaft 42 at a transport speed of 20 cm / min, first, at a position of the can 43, a sputter cathode 56 is provided on one surface (O surface) of about 3,000Å of Co-.
A Cr film was formed. Next, at the position of the key 44, the sputter cathode 58 is used to deposit Co- of approximately 3,000Å on the other surface (I surface).
A Cr film was formed and wound on the winding shaft 45.

In this way, the polyimide film having the Co-Cr film formed on both sides is reversed again and conveyed from the winding shaft 45, and 1 × 10 6 again.
After exhausting to ^-6 Torr or less, stop the Ar gas ejection and maintain the oxygen gas at about 5 × 10 ^-3 Torr, switch the polarity of the spatula, and perform reverse spattering in the oxygen atmosphere at the positions of 43 and 44. After the surface was oxidized, it was wound on the winding shaft 42.

Then, the oxygen atmosphere is changed to the Ar atmosphere and the polarity of the spatter is returned to the original state, and the film is re-transferred from the winding shaft 42, and the cans 43 and 44 are transferred.
A carbon protective layer having a thickness of 200Å was formed from the carbon cathodes 55 and 57 at the position of and was wound around the winding shaft 45.

The perpendicular magnetic medium thus prepared was cut into a disk having a diameter of 3.5 inches and incorporated into a commercially available disk jacket.

After recording with a commercially available 3.5 floppy disk drive, it was rotated at 600 rpm and the number of passes until the driving stopped while running while monitoring the playback signal was measured. (maximum
The test was stopped after 10 million passes. ) For comparison, the same test was carried out by making one that was not subjected to the oxidation treatment (reverse sputtering process in an oxygen atmosphere) and one that was provided with only the Co-Cr layer in the above preparation.

Ten samples were prepared and tested.

The obtained results are shown in FIG.

〔The invention's effect〕

As is clear from the results shown in Fig. 2, the sample provided with only the Co-Cr film became unable to run after about 100 passes, and the sample provided with the carbon protective layer without oxidation treatment had 10,000 passes. From 10 to 10 million passes, there was variation in running durability, and reproducibility was poor. On the other hand, according to the present invention, it was possible to manufacture the perpendicular magnetic medium with remarkably excellent durability in which the running path was close to 10 million paths.

Although the above embodiment shows the case where the oxidation treatment is performed by the reverse sputtering, the oxidation treatment can be performed by the glow treatment. Also, almost the same result was obtained by using nitrogen instead of oxygen.

Further, not only the Co—Cr film but also the Co—Cr film may be provided on the soft magnetic layer as described above.

[Brief description of drawings]

FIG. 1 is a schematic view showing an example of an apparatus for producing a perpendicular magnetic medium of the present invention, and FIG. 2 is a view showing results of a traveling path test in the embodiment. 43,44 …… Kyan, 55,57 …… Carbon cathode, 56,58
...... Co-Cr cathode.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Akira Nahara 2-12-1, Ogimachi, Odawara-shi, Kanagawa Fuji Photo Film Co., Ltd. (56) Reference JP-A-60-57535 (JP, A) Kai 61-117728 (JP, A)

Claims (2)

[Claims] 1. A method of manufacturing a perpendicular magnetic recording medium, comprising providing a magnetic layer having perpendicular magnetic anisotropy and a protective layer on at least one surface of a non-magnetic substrate by sputtering.
After providing the magnetic layer, place the cylindrical can on the target.
A method of manufacturing a perpendicular magnetic recording medium, characterized in that sputtering (reverse sputtering) is performed with a (minus) polarity to oxidize or nitrid the surface of the magnetic layer, and then a protective layer is provided. 2. The method of manufacturing a perpendicular magnetic recording medium according to claim 1, wherein the nonmagnetic layer and the oxide layer or the nitride layer are formed in the same vacuum chamber.