JPH0363920A - Magnetic recording medium and its production - Google Patents

Abstract

PURPOSE:To enhance the coercive force of the medium and to control the variance of the coercive force by adjusting the oxygen content of the magnetic film to <3atom% based on the metallic elements in the entire magnetic film. CONSTITUTION:A base layer 2 is formed on a nonmagnetic substrate 1. An intermediate layer 3 of Cr, the magnetic layer 4 of a Co-Ni-Zn alloy and a protective layer 5 of C are successively formed. A corrosion-resistant additive such as Zr and Pt is incorporated into a metallic magnetic film, especially a Co-Ni-based metallic magnetic film, to obtain the magnetic recording medium consisting of an alloy magnetic film of >=3 element, and the oxygen content is controlled to <3atom%. Consequently, the variance of the coercive force is reduced, and a high coercive force is obtained.

Description

Detailed Description of the Invention [Field of Industrial Application] The present invention relates to a magnetic recording medium and a method for manufacturing the same, and in particular, by controlling the oxygen content of a magnetic film, coercive force H
The present invention relates to a magnetic recording medium that optimizes c and reduces variations in coercive force, and a method for manufacturing the same.

[Conventional technology]

Conventionally, in order to improve the magnetostatic properties, especially the coercive force, of magnetic recording media, and to prevent deterioration of properties over time due to oxygen corrosion and maintain the properties, the oxygen partial pressure of the atmospheric gas during magnetic film deposition has been increased. There are known ways to do this. For example, in a film formation method by vapor deposition of a Go or Go-Ni metal magnetic film,
JP-A-57-58231 and JP-A-57-5823
As described in Japanese Patent Publication No. 57-58238, the gas pressure ratio of Ar gas, Kr gas, Xe gas, or a mixture thereof and Oz gas (Ar10z
) is 1 to 1000, and the deposition rate is 102 and the gas pressure ratio is 20.
There are some materials that guarantee magnetic properties by setting the speed to ~6700 μm/min/Torr. In addition to the above mixed gases, He or O! Gas pressure ratio of gas is 100
There is also a technique that guarantees magnetic properties by controlling the magnetic properties to be less than 0 (for example, Japanese Patent Laid-Open No. 57-55537).

JP-A-57-58236, JP-A-57-5823
Publication No. 7, JP-A-57-152546, JP-A-5
Publication No. 7-152547, and JP-A-57-1525
(See Publication No. 48).

In addition, as described in Japanese Patent Application Laid-open No. 57-113417, Co is deposited on Co acid oxide in a magnetic film using vapor deposition technology.
The volume ratio with oX is 0.25 to Y/(X+Y)
There is also a technique in which an alloy magnetic thin film is formed on a substrate so that the magnetic flux density is 0.40.

Furthermore, as described in Japanese Patent Publication No. 60-33289, the composition ratio of Go and Ni is set in the range of 10 to 55% by weight of Ni, and G in the magnetic film.

The oxygen content is 3 to 45 at to the sum of the number of atoms of Ni and Ni.
There is also a technique in which a high coercive force is obtained by specifying %, and the variation in coercive force is reduced.

In any case, the above-mentioned conventional technology prevents corrosion due to oxidation by increasing the oxygen content in the magnetic film as much as possible, suppresses deterioration of magnetostatic properties, especially coercive force, due to changes over time, and improves the quality of magnetic recording media. This is what we have been doing.

[Problem to be solved by the invention]

However, in recent years, as material development has become more active, Co-based magnetic films have been modified from co-Ni alloys to include Ti, V, Cr, Zr, Nb,
3rd such as Mo, Hf, Ta, W, PC, etc. Materials to which a fourth element is added are increasingly being used. It has become impossible to improve the magnetostatic properties of materials to which such corrosion-resistant tertiary and quaternary elements have been added using conventional techniques aimed at increasing oxygen content. In particular, regarding coercive force among magnetostatic properties, magnetic materials containing three or more of the above elements ('l'i, V, Cr, Z in the above Co-Ni system)
r.

It is difficult to improve the characteristics by containing a high concentration of oxygen in magnetic films (adding one or more of Nb, Mo, Hf, Ta, W, and Pt), and on the contrary, the amount of oxygen contained in the magnetic film causes a decrease in coercive force and , has become a major factor in the variation in coercive force.

Therefore, there is an urgent need to develop a magnetic recording medium with high coercive force and excellent magnetostatic properties by controlling the oxygen content in the magnetic film as a new technique.

As a result of various experiments, the present inventors found that, contrary to the conventional tendency of technology to contain oxygen at a high concentration, by reducing the oxygen content, the coercive force was increased and the variation in coercive force was reduced. It has been found that the magnetic properties can be improved, such as by suppressing the magnetic properties. In particular, this improvement in properties is remarkable in magnetic materials containing three or more elements in which the above-mentioned additives are added to the Co--Ni system.

Therefore, the first object of the present invention is to improve the coercive force by controlling the oxygen content in the improved magnetic material to 3 at% or less, thereby suppressing variations in the coercive force and producing stable, high-quality magnetic material. The goal is to provide recording media.

A second object of the present invention is to reduce the oxygen content in the magnetic film to 3 at% or less, and further control the oxygen content within that oxygen content range, thereby increasing the coercive force to the maximum value with a specific magnetic material. An object of the present invention is to provide a magnetic recording medium that can be drawn out and a method for manufacturing the same.

Furthermore, the third object of the present invention is to provide 3a that is compatible with each material composition ratio, even if the magnetic films have different material composition ratios.
It is an object of the present invention to provide a magnetic recording medium having the same coercive force by controlling the oxygen content to t% or less, and a method for manufacturing the same.

[Means to solve the problem]

In order to achieve the first to third objects, the magnetic recording medium of the present invention is adjusted such that the oxygen content in the magnetic film is less than 3 atomic % based on the metal element in the entire magnetic film.

The magnetic film is composed of a Co-Ni-based material, and in particular contains elements of groups 4a, 5a, and 6a of the periodic table (i.e., Ti, V, Cr, Zr, Nb) as additives.

This applies to materials containing at least one of Mo, Hf, Ta, W), and Pt.

For film formation, DC (direct current) or RF (radio frequency) sputtering method, plasma CVD method, vapor deposition method, etc. are used, but the amount of oxygen in the residual gas in the manufacturing chamber or the atmospheric gas introduced during film formation is Through control, the oxygen content (ratio of oxygen to all metal elements) in the magnetic film is adjusted to less than the above-mentioned 3 at %.

Also, in order to adjust the oxygen content to below this value,
Since it is necessary to eliminate oxygen and water that causes oxygen that the substrate and the substrate holder that supports the substrate bring into the vacuum chamber of the film forming apparatus, preheating is performed before film formation.
The substrate and substrate holder are baked out and further heated in a vacuum chamber. This makes it easier to control the oxygen content in the magnetic film during film formation.

In addition, in order to adjust the oxygen content to below the above value,
The ultimate vacuum pressure of the deposition vacuum chamber before deposition is 5X10-
The oxygen gas pressure during film formation can be easily controlled in advance by specifying the oxygen gas pressure to be less than The oxygen content inside is controlled to a predetermined value.

[Effect]

The operation based on the above configuration will be explained.

According to the present invention, a metal magnetic film, particularly a Co--Ni metal magnetic film, contains elements of groups 4a, 5a, and 6a of the periodic table (i.e., Ti, V, Cr, Zr, and Nb).

In a magnetic recording medium made of an alloy magnetic film of three or more elements containing additives such as Mo, Hf, Ta, W) and Pt for corrosion resistance, (conventional method of increasing the oxygen content as much as possible) Contrary to the technique of increasing the coercive force, by suppressing the oxygen content to less than 3 atomic %, it is possible to obtain a high value of coercive force with less variation.

In addition, below, the oxygen content in various compositions is calculated according to the above 3.
An outline of a manufacturing method for obtaining a desired coercive force by adjusting it to a desired value within a range of less than atomic % will be explained.

First, the substrate and substrate holder are baked out, and the previously formed film (
By removing dirt), oxygen and water brought into the deposition vacuum chamber by the substrate and substrate holder during deposition are eliminated. Thereafter, the substrate and substrate holder are loaded into the film forming chamber, and the ultimate vacuum pressure is set to 5×lO-'''Torr or less. When the specified vacuum pressure is reached, the substrate and substrate holder are further heated, and Perform degassing. Sufficient evacuation is performed using a vacuum pump until the vacuum pressure after degassing reaches 5×10 −' Torr.

By the above operations, oxygen gas and water in the film forming vacuum chamber are sufficiently removed. After that, a film forming atmosphere gas is introduced. Oxygen gas in the atmospheric gas enters the magnetic film during film formation, and this determines the oxygen content in the magnetic film.

Therefore, the oxygen content is determined by the level of the oxygen partial pressure in the atmospheric gas. The oxygen partial pressure must be determined in advance because the oxygen content at which the maximum coercive force can be obtained differs depending on the composition ratio. Perform membrane. This makes it possible to easily reproduce the maximum coercive force.

Further, by changing the oxygen partial pressure in the atmosphere for each composition using the above method, it is possible to control magnetic films of different compositions so that they have the same coercive force.

Furthermore, when only one composition is determined, the coercive force can be easily changed by controlling the oxygen content in the magnetic film using the method described above.

Furthermore, it is possible to manufacture magnetic recording media with a stable coercive force with little variation in relation to the controlled oxygen content in the magnetic film, making it possible to continuously and stably supply magnetic recording media of the same quality. .

Furthermore, in order to eliminate the oxygen and water brought in, the number of times the substrate holder is used, which is a factor in bringing in oxygen, is stipulated, and the magnetic recording medium forming film attached to the substrate holder is removed. It also makes it easier to control the oxygen content inside.

〔Example〕

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a sectional view of a magnetic disk, which is an example of the magnetic recording medium of the present invention. In the medium of this example, Al
- An underlayer 2 of N1-P plating is formed on a nonmagnetic substrate l of Mg alloy. The layers above intermediate layer 3 are formed by DC (direct current) sputtering. The intermediate layer 3 is made of Cr, the magnetic layer 4 is made of Co-Ni-Zr alloy, and the protective layer 5 is made of C. A lubricating film 6 is formed on the protective layer by a dip method.

In the above structure, the base layer 2 of N1-P is 10. czm.

Further, the thickness of the Cr intermediate layer 3 is 0.25 μm, and the thickness of the magnetic film 4 is 0.25 μm.
05 μm, and the protective layer was 0.05 μm. The purpose of Zr in the magnetic film 4 is to obtain corrosion resistance. Further, the N1-P layer 2 has a texture (fine grooves arranged in the circumferential direction of the magnetic disk) with a depth of about 0.01 μm.

Next, FIG. 2 shows a magnetic recording medium film forming apparatus for manufacturing the magnetic medium according to this embodiment. In this example, patch-type film formation was performed. A substrate holder with a substrate attached thereto is placed in the preparation chamber 21, and pumps 22 and 23 are used to perform vacuum evacuation. The substrate and substrate holder were previously baked out in a baking oven at 150° C. for 6 hours. It is desirable that the baking temperature and baking time are high and long, but N1
- Care must be taken to ensure that the structure of the P plating does not change due to temperature.

The inside of the vacuum chamber is 5X10-'Tor due to evacuation.
When it reaches the intermediate layer target 24. Magnetic layer target 25. The protective layer targets 26 are moved in this order. In this example, film formation was performed without moving. The intermediate layer and magnetic layer are prepared under a mixed gas atmosphere pressure of 10 mmT of Ar and 0□.
o r r.

The protective film is the same Ar and 02 atmosphere mixed gas pressure 1mm+J
Film formation was performed using Torr. Immediately before film formation, heat the substrate again to 180°C to achieve the desired film thickness.
The input power was determined.

The oxygen content in the magnetic film after film formation was conveniently measured using a fluorescent X-ray measuring device. Furthermore, in order to quantify the number of oxygen counts of fluorescent X-rays, the amount of oxygen during film formation was analyzed using a μm Auger electron spectrometer, and the at% was calculated.

This amount of oxygen is expressed as a ratio of O to all metal elements (Co+Ni+Zr). Also, the magnetostatic characteristics are VS
Measured by M (vibrating magnetic measuring device).

First, as Example 1, the results of changing the oxygen partial pressure in the atmospheric gas during magnetic film formation among the above-mentioned implementation conditions will be explained with reference to FIG. The vertical axis shows the coercive force (its variation is also shown), and the horizontal axis shows the oxygen content in the magnetic film after film formation (a
t%).

In addition, the composition ratio of the magnetic film is 63Co-3ONi-7Zr
It is.

In the magnetic material having this composition, the coercive force reaches its maximum at about 1.5 at%, and the coercive force tends to decrease as the amount of oxygen exceeds that amount. Moreover, after the amount of oxygen exceeds 3 at%, the variation in coercive force increases. Note that, in general, the oxygen content is determined not only by the oxygen partial pressure but also by the film forming conditions (DC,
It also depends on the type of RF sputtering, the sputtering power input, how to prepare and select the target material, etc.
In the case of this example, when baking is performed at the ultimate vacuum pressure of lXl0-'Torr, the oxygen partial pressure (%) is 0.001.0.01.0.1. And, when it is 1.0, the oxygen content (at%) is 0.5 and 1.0, respectively.
, 3.0, 10.0. In any case, 3at%
It is easy to obtain the following oxygen content, 4N (99,
It is sufficient to use Ar with a purity of 99% as in this embodiment.

Next, as Example 2, the magnetic film composition ratio was changed to 54Co-4O.
The material was changed to Ni-6Zr, and the oxygen partial pressure was changed in the same manner as in Example 1. This will be explained using FIG.

In Example 2, as in Example 1, the coercive force changes as the oxygen content changes, but the amount of oxygen at which the coercive force reaches its maximum is different from Example 1, and reaches its maximum value when the amount of oxygen is low. ing. It is also seen that the variation in coercive force increases when the amount of oxygen exceeds about 3 at%.

Furthermore, Ti, V, Cr, Nb, Mo other than Zr
.

Regarding additive elements such as Hf, Ta, W, and PL, similar results were obtained, although the characteristics varied slightly depending on the additive.

That is, in a Co--Ni-based ternary or higher magnetic alloy, the coercive force changes with changes in the oxygen content in the magnetic film, and has a maximum coercive force peak that is unique to the material composition or the &[l acid ratio. Further, as the amount of oxygen increases, variations in coercive force begin to appear, and if it exceeds 3 at%, stable coercive force cannot be obtained. Therefore, according to this embodiment, in order to stabilize the coercive force (eliminate variations), it is effective to set the oxygen content in the magnetic film to less than 3 at %.

Further, according to this embodiment, by determining the relationship between the coercive force and the oxygen content in advance, the oxygen content is controlled within a range of less than 3 at% so that the maximum coercive force is obtained for each composition ratio. Moreover, the oxygen content can be controlled within a range of less than 3 at % so that a constant coercive force is always obtained even if the composition ratio is different.

Furthermore, according to this example, by controlling and changing the oxygen content in the magnetic film at only one composition ratio,
It is possible to select the target value of coercive force.

Next, as Example 3, the ultimate vacuum pressure in the vacuum chamber (
The vacuum pressure reached before applying the atmospheric gas for film formation (the highest vacuum pressure necessary to obtain the desired 02 content) was varied. The relationship between the ultimate vacuum condition and the coercive force will be explained using FIG. Here, the total gas pressure of the atmospheric gas is 10 mTorr, the oxygen partial pressure in the atmospheric gas is constant at 0.01 or less (4N or 99.99% Ar used), and the heating of the substrate and substrate holder is The conditions were also kept constant. As the ultimate vacuum pressure increases, a decrease in coercive force is observed. Further, the variation becomes large.

At this time, the oxygen content in the magnetic film was proportional to the ultimate vacuum pressure, and when the ultimate vacuum pressure was low, the amount of oxygen was small, and when the ultimate vacuum pressure was high, the amount of oxygen was large. According to this example, the ultimate vacuum pressure in the film forming vacuum chamber is 5X.
If the film is formed at a pressure of 10-' Torr or less, the oxygen content in the magnetic film can be made less than 3 at %, which is effective in increasing coercive force and reducing variations. Furthermore, since the base of the ultimate vacuum pressure is constant, there is an effect that it becomes easier to control the oxygen partial pressure in the film forming atmosphere.

Here, the above embodiments are summarized in FIG. 6.

In the conventional method, the variation in coercive force is large and the maximum coercive force is about 9000e, but according to this embodiment, the variation in coercive force is suppressed to about 1/2 with the same composition.

The maximum coercive force can be increased by about 1000e compared to the conventional one.

In a past report, it was reported that variations become noticeable when the oxygen content in the magnetic film is less than 3% (see the above-mentioned Japanese Patent Publication No. 60-33289), but this tendency was not observed in this example. On the contrary, the results show that the greater the oxygen content, the greater the variation.

In the above embodiment, the substrate 1 is made of aluminum alone or glass instead of an aluminum alloy such as Al-Mg, and the rest is the same as the above embodiment, the base layer 2 is N1-P plating, the intermediate layer 3 is Cr, and the magnetic layer is 4, a Go-Ni alloy can be used. Further, the protective film layer 5 may be made of carbide ceramic or nitride ceramic instead of carbon. The thickness of each layer is 10 μm or less for the base layer, 1 μm or less for the intermediate film, and 0.1 μm or less for the magnetic film.
It is preferable to form the protective film to a thickness of 0.1 μm or less.

To form the base film above the intermediate layer 3, a DC (direct current) or RF (radio frequency) sputtering method, vapor deposition method, or plasma CVD method is used, and the oxygen content in the formed magnetic film is as described above. (to 3 at% or less).

Theoretically, the oxygen content may be zero, but in terms of mass production technology, it can be efficiently implemented up to about 0.1 at%.

〔Effect of the invention〕

As explained in detail above, according to the present invention, a metal magnetic film, particularly a Go-Ni magnetic film, has an alloy magnetic film containing three or more elements, in which additives such as Zr are added in consideration of corrosion resistance. In magnetic recording media, the oxygen content in the magnetic film is
By controlling the coercive force to less than at %, excellent effects such as suppressing variations in coercive force and obtaining a high (maximum) coercive force can be achieved.

In addition, the ultimate vacuum pressure in the vacuum chamber for forming the magnetic film was set to 5×10−
? After reducing the oxygen content to below 3 at.
It can be easily adjusted to a desired value within a range of less than %.

In addition, for magnetic films with various compositions, variations in coercive force can be reduced by adjusting the oxygen content to achieve the maximum coercive force, or by adjusting the oxygen content so that the coercive force is always the same. It can be suppressed.

In this way, high quality and stable magnetic recording media can be continuously provided.

[Brief explanation of drawings]

FIG. 1 is a cross-sectional view of a magnetic disk recording medium according to an embodiment of the present invention, FIG. 2 is a longitudinal cross-sectional view of a magnetic recording medium film forming apparatus for manufacturing the magnetic disk recording medium of the same embodiment, and FIG. A characteristic diagram of the oxygen content in the magnetic film versus coercive force when the magnetic film composition is 63Co-3ONt-7Zr, FIG. 4 is a similar characteristic diagram when the magnetic film composition is 54Co-4ONi-6Zr, and FIG. The figure shows the relationship between the coercive force and the ultimate vacuum pressure in the film-forming vacuum chamber, and FIG. 6 shows the characteristics comparing each embodiment of the present invention and the conventional example. 1..--1--nonmagnetic substrate, 2--..--base layer, 3--.--1 intermediate layer, 4--1--.magnetic layer (magnetic film), 5-------Protective layer (protective film), 6
・−1−−−−−Lubricating film. Fig. 1 Fig. 3 Fig. 112 Magnetism / 11 Suno Ryotoke 4 amount (a 1%) 63Co-
3ONI-7zr Fig. 4 1.0 2.0 3,0 4.0 5.0 6. Content of chordae in Q-wandering skin (at%J 54Co-4ONi-6i!r Figure 5 lXl0'-'IxlO-'IxlO-' reached dL'Jjkg: Pressure '

Claims (1)

[Scope of Claims] 1. A magnetic recording medium comprising a metal magnetic film in which the oxygen content in the magnetic film is controlled to less than 3 atomic % based on the metal element of the entire magnetic film. 2. The magnetic film has Co and Ni as main components, and each element of groups 4a, 5a, and 6a and Pt as additives.
2. The magnetic recording medium according to claim 1, comprising at least one of the following. 3. In order to control the oxygen content in the magnetic film to less than 3 atomic % with respect to the metal elements in the entire magnetic film, the ultimate vacuum pressure in the vacuum chamber for forming the magnetic film was set to 5×10^-^7 3. The method of manufacturing a magnetic recording medium according to claim 1, wherein the magnetic film is formed in a film forming atmosphere gas with a controlled oxygen partial pressure after the temperature is reduced to below Torr.