JPS62175925A - Vertical magnetic recording medium and its production - Google Patents

Abstract

PURPOSE:To obtain a vertical magnetic recording medium having good reproducibility and remarkably improved running durability by providing a protective layer on the surface of a magnetic layer after forming an oxide layer or nitride layer thereon. CONSTITUTION:A vertically magnetized film having the axis of easy magnetization in the direction perpendicular to the film plane, for example, Co-Cr film is formed by, so-called, thin film forming system such as sputtering, vacuum deposition or ion polating on one or both faces of a nonmagnetic substrate. The surface of the formed magnetic layer is subjected to an oxidation or nitriding treatment and thereafter, the protective layer is provided thereon. The oxidation or nitriding treatment may be executed by a glow discharge treatment inn the presence of oxygen or nitrogen or reverse sputtering in the presence of oxygen or nitrogen. Implantation of oxygen ions or nitrogen ions onto the surface of the magnetic layer by using an ion gun is equally satisfactory. Carbon, SiO2, Co-O-Cr, Cr-O, etc. are used as the protective layer and above all, the carbon is more particularly preferable. The preferable film thickness of the protective film is 0.002-0.1mum, more particularly 0.005-0.05mum.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a perpendicular magnetic recording medium and a method of manufacturing the same, and more particularly to a perpendicular magnetic recording medium with improved running durability and a method of manufacturing the same.

[Conventional technology]

In recent years, a perpendicular magnetization recording method has been proposed in which a magnetic recording medium having an axis of easy magnetization in a direction perpendicular to the film surface of the recording medium is angled. This perpendicular magnetization recording method f provides excellent reproduction output because the demagnetizing field in the recording medium decreases at tt4 when the recording density increases, and can be said to be essentially a method suitable for high-density recording.

In order to perform magnetic recording using such perpendicular magnetization recording method, a magnetic recording medium having an axis of easy magnetization in a direction perpendicular to the film surface of the recording medium is required. Such perpendicular magnetic recording media are produced by coating a Co-Cr alloy or the like on a substrate or support made of a non-magnetic material such as a polymeric material or a non-magnetic metal.
Methods such as the tsutaring method are known.

In addition, in order to improve the recording and reproducing efficiency during perpendicular magnetization recording and reproducing, a high magnetic permeability layer made of a soft magnetic material is provided as an underlayer under the perpendicular magnetic recording layer made of the co-Cr alloy film.
For example, a so-called two-layer model perpendicular magnetic recording medium provided with a permalloy (Ni--Fe alloy) film is known.

Furthermore, in flexible disks and the like that use the perpendicular magnetization recording method, so-called double-sided double-layer perpendicular magnetic recording media, in which the double-layer perpendicular magnetic recording medium is formed on both sides of a support, have a larger recording capacity. It is excellent because it improves curls and is easy to curl. ``Perpendicular magnetic media of the above-mentioned types are also manufactured by applying the above-mentioned materials to a support continuously or discontinuously using a sputtering device.

[Problem that the invention seeks to solve]

Such perpendicular magnetic media is expected to be used as a recording medium suitable for high recording densities, such as magnetic tapes and magnetic disks.
One major problem is that running durability is generally very poor; for example, in the case of a perpendicular magnetic recording disk with a Co-Cr alloy film, after about 10,000 runs, the alloy layer on the surface condenses, making it impossible to run. It often becomes.

In order to solve such problems, Kazen, 5i02
, BN (Japanese Unexamined Patent Publication No. 58-133627), StC (
It has been proposed to provide a protective layer such as JP-A-58-130437 on the surface of the magnetic layer by sputtering or the like.

However, even with these treatments, the improvement in running durability is still insufficient, and in particular, even if the manufacturing process is the same, the reproducibility of the product is poor, and products with good durability and products with extremely poor durability can be obtained. There was a problem in that it was not possible to obtain a product with consistently good durability.

Therefore, an object of the present invention is to provide a perpendicular magnetic recording medium with good reproducibility and significantly improved running durability, and a method for manufacturing the same.

[Means for solving problems]

The present invention was developed as a result of extensive research to solve the above problems.
The present invention has been achieved by discovering that by forming an oxide layer or a nitride layer on the surface of a magnetic layer and then providing a protective layer, it is possible to obtain a perpendicular magnetic recording medium with significantly improved durability with good reproducibility. .

That is, the present invention provides a perpendicular magnetic recording medium in which a magnetic layer having perpendicular anisotropy and a protective layer are provided on at least one surface of a nonmagnetic substrate, in which an oxide layer or a nitride layer is completely formed on the surface of the magnetic layer. In a perpendicular magnetic recording medium and a method for manufacturing a perpendicular magnetic recording material by providing a magnetic layer having perpendicular magnetic anisotropy and a protective layer on at least one surface of a non-magnetic substrate by streaking, This method of manufacturing a perpendicular magnetic recording medium is characterized in that after providing a layer, the surface thereof is oxidized or nitrided, and then a protective layer is provided.

The present invention will be explained in detail below.

In the present invention, first, a perpendicularly magnetized film having an axis of easy magnetization in a direction perpendicular to the film surface, such as a Co-Cr film, is formed on one or both sides of a nonmagnetic substrate using a so-called thin film formation method such as sputtering, vacuum evaporation, or ion blating. to form.

In this case, before forming the perpendicular magnetization film, a soft magnetic film with low coercive force or high magnetic permeability, such as a zo-Malloy film, is similarly coated.
It may also be provided by tucking or the like. Further, the perpendicular magnetization film and the like may be a single layer or may be composed of a plurality of layers.

Further, a nonmagnetic underlayer may be provided between the substrate and the perpendicular magnetization layer, or a nonmagnetic intermediate layer may be provided between the soft magnetic layer and the perpendicular magnetization layer. Therefore, the magnetic layer referred to in the present invention includes cases in which only a perpendicular magnetization film as described above is provided, and cases in which a soft magnetic film and a perpendicular magnetization film are provided. Although it has a particularly remarkable effect on film-like polymer materials such as , J-limide, and polyamide, it is also applicable to metal materials and non-metal materials such as glass.

Materials for the soft magnetic film include Ni-Fe, Ni-
Not limited to the alloys such as Fa-Mo, Ni-Fe-Mo-Cu, etc., but also F@, Fe-Al-S
i, Fe-Ni-0, Fe-Tf, Ni-F
e-Co-Cr-Mn, Fe-5f-B.

Fe-B-C, Fe-AI, Co-V-Fe,
Co-Ta.

Co-Zr, Co-Nb-Zr, Co-Ti
XCo-Nb-TaXCo-Ni-ZrXFe-N
i-P, Fe-Co-Zr, Co-Mo
- So-called soft magnetic alloy materials such as Zr can also be applied.

The film thickness is preferably about 0.03 to 5 microns, particularly about 0.1 to 1 micron.

As a perpendicularly magnetized film, it is necessary that the axis of easy magnetization is oriented in a direction substantially perpendicular to the surface of the support 1, and C is known as a material for perpendicularly magnetized films.

An alloy phase material containing Cr and Cr as main components is desirable.

The film thickness is selected to be about 0.03 to 5 microns, and preferably about 0.05 to 1 micron.

As the film forming means, vapor deposition, sputtering, etc. are used, but it is preferable to use a so-called continuous sputtering chamber having a plurality of high-speed sputtering chambers arranged around a plurality of cylindrical cans, as shown in the examples below. .

In the sputtering chamber, 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 separate targets.

When forming a hard magnetic film such as a permalloy film, the temperature of the cylindrical core is preferably 30° C. or higher to prevent magnetic anisotropy in the plane of the hard magnetic film from occurring.

On the other hand, if the can temperature is too high, gas release from the support, precipitation of oligomers, etc. will occur, so a temperature of 90° C. or lower is desirable.

In order to particularly reduce magnetic anisotropy and film surface irregularities,
A temperature of 45 to 65°C is particularly desirable. On the other hand, c.

When forming a -Cr film, it is desirable to heat the cylindrical can to 90°C or higher in order to obtain the desired He (perpendicular) magnetization, and to obtain a He (perpendicular) perpendicular magnetization film, it is desirable to heat the cylindrical can to 120°C or higher. The above is particularly desirable.

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

Oxidation treatment or nitriding treatment is performed by glow discharge treatment (02 or N210-'~1O-4Tor) in the presence of oxygen or nitrogen.
Alternatively, reverse sputtering may be performed in the presence of oxygen or nitrogen, or oxygen ions or nitrogen ions may be implanted onto the surface of the magnetic layer using an ion gun. In the case of sputtering, a magnetic layer (cylindrical can +, target -) is provided by sputtering, the polarity is reversed, and 10-1 to 10 of oxygen or nitrogen is applied.
Reverse sputtering may be performed by applying one voltage in an atmosphere of -' Torr.

A protective layer is then provided by sputtering or the like on the surface of the magnetic layer on which the oxide layer or nitride layer has been formed in this manner.

As a protective layer, Car/y, 5i02, Co-0-C
rXCr-0 etc. are used. Among these, carzene is particularly preferred.

The thickness of the protective layer is preferably 0.002 μm to 0.1 μm, particularly 0.005 to O.OS.

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

〔Example〕

FIG. 1 is a schematic diagram showing an example of a sputtering apparatus used for producing the perpendicular magnetic recording medium of the present invention.

A double-sided double-layer perpendicularly magnetized medium was produced using the double-sided continuous sputtering apparatus shown in FIG. A roll-shaped polyimide film 41 with a thickness of 50 microns is set on the delivery shaft 42, and an intermediate roller and a cooled cylindrical cap 743.44 are set.
The film is then wound onto a winding shaft 45. The vacuum chamber was roughly divided into three parts: a delivery chamber 46, a sputtering chamber 47, and a winding chamber 48. Each chamber was partitioned by a partition wall 49.50, and each chamber was evacuated by exhaust systems 51.52 and 53.34, respectively. .

The sputtering chamber is equipped with DC planar magnetron type sputtering cathodes 55, 57 and Co
-Cr target (Co82-Cr 18% by weight
) was provided with an RF planar magnetron type sputter cathode 56,58.

The sputtering chamber 47 of such a sputtering device is
After evacuation to a pressure of 10-torr or less,
Introduce Ar gas through the gas introduction system 59, approximately 5 x 10-
It was maintained at 3 torr. Delivery shaft 42 p 20 m/-
On the polyimide film 41 sent out at a conveyance speed of
First, at the position of the can 43, Co-Cr of about 3,000X is applied to one side (0 side) by the sputter cathode 56.
- Formed a film. Next, at the position of the can 44, the other surface (I surface) is coated with a sputter cathode 58 of about 3
．． A Co-Cr film of 000X was formed and wound up with a winding shaft 45.

The polyimide film with the Co-Cr film formed on both sides in this manner is reversed again and conveyed from the take-up shaft 45, and after being evacuated again to below IX10 Torr, the Ar gas blowout is stopped and the oxygen gas is reduced to approximately 5X10 Torr. The polarity of sputtering was then changed, reverse sputtering was performed in an oxygen atmosphere at position 1 of cans 43 and 44, and both surfaces were subjected to oxidation treatment, and then wound onto a winding shaft 42.

Next, the oxygen atmosphere is changed to an Ar atmosphere, the polarity of the sputter is returned to its original state, and the sputter is retracted from the winding shaft 42 again, and the can 43
At positions 44 and 44, a protective layer of shicasene was formed by cutting the shicasene cathode 55° and 57 degrees to form a 200×-1′ layer, and the protective layer was wound around the winding shaft 45.

The perpendicular magnetic media thus prepared were cut into 3.5 inch diameter disks and assembled into commercially available disk jackets.

After recording with a commercially available 3.570 disc drive, it was rotated 600 r, p, m, and T, and the disc drive was run while monitoring the reproduction signal, and the number of passes until it stopped running was measured. (The test was stopped at a maximum of 10,000,000 zos.) For comparison, the above preparation without oxidation treatment (reverse sputtering treatment in oxygen atmosphere t) and Co -C
A similar test was conducted using a product with only the r layer.

Ten samples of each were made and tested.

The results obtained are shown in Figure 2.

〔Effect of the invention〕

As is clear from the results in Figure 2, the sample with only a Co-Cr film cannot run at temperatures above about 1o, ooo, -e, and a case/protective layer is provided without oxidation treatment. However, the running durability varied from 10,000 passes to 10,000,000 passes, and the reproducibility was poor. On the other hand, in the case of the present invention, it was possible to produce perpendicular magnetic media with excellent durability and high reproducibility, each having a travel path of approximately 10 million cess.

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

In addition to the Co--Cr film, a Co--Cr film may be provided on the soft magnetic layer as described above.

[Brief explanation of drawings]

FIG. 1 is a schematic diagram showing an example of an apparatus for manufacturing a perpendicular magnetic medium of the present invention, and FIG. 2 is a diagram showing the results of a running path test in the example. 43.44... Can, 55.57... Carzen cathode, 56, 58-Co-Cr cand. Figure 1 Figure 2 Amendment to Figure Procedures 1.1 1986 Special IJeR No. 12100 2, Name of invention Perpendicular magnetic recording medium and its manufacturing method 3, Person making the amendment Relationship to the case: Patent Yamazure v5 Name (520) Fuji Photo Film Co., Ltd. 4, Agent 100 Address Kasumigaseki Building 2, 3-2-5 Kasumigaseki, Chiyoda-ku, Tokyo
9th floor Kasumigaseki Building Post Office P.O. Box No. 49 Telephone (58
1) -9601 ((cut) 6. Number of inventions increased by amendment: 0 (2) The "Detailed description of the invention" column of the specification is amended as follows. 1) IMi, page 3, 15 Correct "high recording density j" in line 1 to "high density recording". 2) Correct "10,000 times" in line 19 on page 3 of the same book cylinder to "r100 times". 3) "Condensation" on page 6, line 20 of the same ministry is corrected to "scrape." 4) "Hard magnetic film" on page 7, line 20 of the same ministry is replaced with "soft magnetic film"
and correct it. 5) Place it after "desirable." on page 8, line 1 of the Ministry of Education. 6) "Magnetic anisotropy..." on page 8, lines 5-6 of the same S.
Delete “desirable”. 7) Delete "Dozutsu Can wo +" on page 8, line 20 of the same book. 8) Doho No. 9, page 8, line f) r car g:y J
(7) Insert K rMos2.5iOJ afterwards. 9) Delete the phrase "cooled down" from lines 3 to 4 on page 10 of the same book. 10) On page 10, line 15 of the specification, insert ``heat and hold the can at 150 cVC'' after ``after exhausting Makabe''. 11) “2Q 11111/f” on page 10, line 17 of the same book
ill! Correct J to "r20cm/order". 12) rlo, ooo-gusu, page 12, line 14 of the same book.”
is corrected to "100-zosu". Figure 2

Claims (3)

[Claims] (1) In a perpendicular magnetic recording medium in which a magnetic layer with perpendicular anisotropy and a protective layer are provided on at least one surface of a nonmagnetic substrate, an oxide layer or a nitride layer is formed on the surface of the magnetic layer. Features of perpendicular magnetic recording media. (2) In a method of manufacturing a perpendicular magnetic recording material by 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, the surface is oxidized or 1. A method for manufacturing a perpendicular magnetic recording medium, which comprises performing a nitriding treatment and then providing a protective layer. (3) Claim (2) characterized in that the formation of the magnetic layer and the formation of the oxide layer or nitride layer are performed in the same vacuum chamber.
) The method for manufacturing a perpendicular magnetic recording medium according to item 1.