JPH07320257A - Magnetic recording medium and manufacturing method thereof - Google Patents

Abstract

(57) [Abstract] [Purpose] To obtain a magnetic recording medium manufactured by a simple process, excellent in corrosion resistance and having a high recording density. Further, by applying this, a magnetic disk device having high recording density and high reliability is realized. [Structure] The surface of the magnetic recording layer of the magnetic recording medium which is in contact with the protective film layer is oxidized to a film thickness of 25 Å or less. The oxide film layer is formed by mixing oxygen in a sputtering gas atmosphere at a ratio of 50% or more at the end of formation of the magnetic recording layer by sputtering, or by forming the medium with a partial pressure of 25% after forming the magnetic recording layer.
% Or more to form an in-plane uniform film by a method of holding it in an oxygen atmosphere, and in any case, subsequently, a protective film layer containing carbon as a main component is continuously formed. [Effect] It is possible to realize a magnetic recording medium having high corrosion resistance and capable of achieving high recording density, and a magnetic disk device having high recording density and high reliability.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetic recording medium having excellent corrosion resistance and high reliability and capable of reducing a space between a magnetic head and a magnetic recording layer, a manufacturing method thereof, a manufacturing facility, and a magnetic disk device. .

[0002]

2. Description of the Related Art In order to improve the recording density of a magnetic disk device, it is an effective means to reduce the distance between a magnetic recording layer of a magnetic recording medium and a magnetic head. In response to this, the protective film layer that protects the magnetic recording layer is further thinning. A hard carbon protective film containing carbon as a main component (hereinafter abbreviated as carbon film) formed by a sputtering method, a CVD method, or the like has been widely applied to this protective film layer. In addition to the fact that the carbon film itself is hard and can be made thin, it is superior in adhesion to the magnetic recording layer and the performance of adsorbing fluorocarbon-based lubricants compared to other materials. This is because it is suitable for ensuring reliability.

However, in the above magnetic recording medium, even if the carbon film is evenly adhered and there are no fine defects or the like, the magnetic recording layer and the Al substrate, for example, may be formed depending on the environment and usage of the magnetic disk device. There is a problem that corrosion occurs in the magnetic recording layer due to the fact that the metal atoms of the underlayer made of Ni and Cr of the Ni-P plated layer react with water molecules in the atmosphere and combine with each other. This corrosion not only erases the magnetic recording of the magnetic recording layer, but also stains on the magnetic head grow in the direction perpendicular to the magnetic recording medium, and the height grows more than the distance between the magnetic recording medium and the magnetic head.
It also causes magnetic recording destruction in other parts. Further, this corrosion becomes more remarkable when the thickness of the carbon film is set to about 200 Å or less in order to reduce the distance between the magnetic recording layer and the magnetic head.

Therefore, in order to improve the corrosion resistance, it is known to form a nonmagnetic metal oxide or a nonmetal oxide between the magnetic recording layer and the carbon protective film by an RF sputtering method or the like in an oxygen atmosphere ( Japanese Patent Laid-Open No. 1-27190
8 and JP-A 1-271915).

[0005]

However, according to the prior art, due to the problem of adhesion between the non-magnetic metal oxide or the non-metal oxide and the magnetic recording layer and the carbon film, the material must be sufficiently considered, and the manufacturing process itself. However, there is a problem that it becomes complicated.

Further, since the non-magnetic metal film layer or the non-metal oxide layer is formed on the magnetic disk by the RF sputtering method with a thickness of several tens or less, the non-magnetic metal film layer or the non-metal oxide layer is uniformly stabilized. It is extremely difficult to form. Therefore, in order to cover the entire magnetic recording medium and obtain the desired corrosion resistance, the average in-plane value must be formed to be about 50 Å or more. In this case, as a result, the distance between the magnetic recording layer and the magnetic head increases, and the recording density deteriorates. Further, according to this, there is a problem that it takes time to grow the oxide film.

Therefore, an object of the present invention is to provide a magnetic recording medium manufactured by a simple process, excellent in corrosion resistance and having a high recording density, and a manufacturing method thereof.

[0008]

In order to solve the above problems, the present invention oxidizes the magnetic recording layer on the side in contact with the protective film layer, and the film thickness of the oxide film layer is about 25 Å or less. Corrosion resistance is obtained.

When forming a magnetic recording layer by sputtering in a gas atmosphere of at least one of Ne, Ar, Kr, and Xe, after forming a desired film thickness, a partial pressure of 50% is continuously applied in the sputtering atmosphere gas. By mixing the above oxygen, an oxide film can be rapidly formed. The oxide film layer is preferably a metal oxide film containing at least one element of Co, Cr and Ta.

As another method of forming the oxide film layer, the medium is kept in an atmosphere containing oxygen, preferably 20 Torr or less, for a certain period of time during the formation of the magnetic recording layer by sputtering so that the medium is uniformly formed in the plane. Can be formed. One of the reasons why the pressure is preferably 20 Torr or less is that the partial pressure of water is easily controlled to be a certain pressure or less, and further the degree of vacuum in the adjacent film forming chamber is not deteriorated. Further, when the oxygen partial pressure in the oxygen atmosphere is 25% or more, an oxide film having excellent corrosion resistance can be formed in a short time.

By providing an oxide film layer on the magnetic recording layer, a sufficient function as a protective film layer is provided even if the protective film layer containing carbon as the main component formed on the oxide film layer is 150 Å or less. it can.

[0012]

According to the present invention, since the oxide film layer is uniformly formed on the surface of the magnetic recording layer in contact with the protective film layer, the oxide film layer serves as a passivation film and is not affected by the presence of atmospheric air. It is possible to prevent the moisture from binding to the metal atoms of the magnetic recording layer or the underlayer and to obtain a magnetic recording medium having excellent corrosion resistance.

By using the manufacturing method of the present invention, this oxide film layer can sufficiently prevent corrosion when the thickness of the oxide film layer is 25 Å or less, and is a thin film of the protective film layer containing carbon as a main component. It becomes possible to increase the recording density of the magnetic recording medium.

Furthermore, by manufacturing a magnetic disk device using the above magnetic recording medium, a highly reliable device can be obtained.

[0015]

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

FIG. 1 is a sectional structural view of a magnetic recording medium which is an embodiment of the present invention.

Aluminum alloy substrate 1-1 (outer diameter 95 m
m, inner diameter 25 mm, thickness 0.8 mm) Ni-P plating 1-2
The surface of the non-magnetic substrate 1 subjected to is polished to be smooth, and further, texture processing and cleaning are performed using a tape and abrasive grains. After the Cr underlayer 2 and the CoCrTa magnetic recording layer 3 are sequentially formed by the sputtering method, C of the magnetic recording layer 3 is formed.
The oxide film layer 4 is formed by oxidizing at least one element of o, Cr, and Ta. Next, a carbon film layer 5 and a fluorocarbon-based lubricating layer 6 are formed by film formation.

(Example 1) Aluminum alloy substrate 1-1
The non-magnetic substrate 1 having Ni-P plating 1-2 thereon was polished to be smooth, and further, texture processing and cleaning were performed using a tape and abrasive grains. After that, the substrate 1 which had been subjected to the above-mentioned texture processing and cleaning was introduced into a DC magnetron type sputtering apparatus which had been evacuated to a degree of vacuum of about 3.0 × 10 −7 Torr or less in advance, and heated to 280 ° C. in a heating chamber. This substrate 1 was conveyed to a base layer forming chamber, and a Cr base layer 2 was deposited at a substrate temperature of 270 ° C. and an Ar gas pressure of 3 mTorr to a thickness of 500 Å. Next, it is conveyed to the magnetic recording layer forming chamber and the CoCrTa magnetic recording layer 3 is heated to a substrate temperature of 270 ° C.
After forming a film with a thickness of 260 Å at an Ar gas pressure of 3 mTorr, oxygen is introduced into the sputtering atmosphere and the ratio of Ar: oxygen is mixed at 50:50 to form an oxide film layer 4 of Co, Cr, and Ta at a substrate temperature of 270. ℃, gas pressure: 5mTorr thickness 5
The film was formed with a change of up to 25 Å. The film thickness of the oxide film layer 4 was controlled by the film formation time while keeping the input power constant. Then, the carbon film layer 5 is transferred to the protective film layer forming chamber and the carbon film layer 5 is heated at a substrate temperature of 260 ° C.
A film having a thickness of 150Å was formed at an Ar gas pressure of 4 mTorr. After lowering the room temperature, tape cleaning is performed, and a fluorocarbon-based lubricating layer 6 is provided in an amount of 25 Å. 1-3 were created.

Table 1 shows sample No. And the relationship of each condition are shown.

[0020]

[Table 1]

(Embodiment 2) Sample No. 1 was prepared with the same Ar: oxygen ratio of 0: 100 in the sputtering atmosphere when the oxide film layer 4 was formed by the same manufacturing method as in Embodiment 1. 4-6 were created.

(Embodiment 3) By the same manufacturing method as in Embodiment 1, sample No. 2 was prepared by setting the ratio of Ar: oxygen in the sputtering atmosphere at the time of forming the oxide film layer 4 to 80:20. 7-9 were created.

Comparative Example 1 By the same manufacturing method as in Example 1, the oxide film layer 4 is not provided and the carbon film layer 5 is provided in the range of 150 to 40.
Sample No. was formed by forming a film on 0Å. 10 and 11 were created.

Comparative Example 2 An oxide film layer 4 was formed in a thickness of 50 to 100 Å by the same manufacturing method as in Example 1, and sample N
o. 12 and 13 were created.

(Embodiment 4) FIG. 2 is a schematic view of a DC magnetron type sputtering film forming apparatus having an oxide film layer forming chamber, and FIG. 3 is a view of the oxide film layer forming chamber 11 therein.

Ni-P on the aluminum alloy substrate 1-1
The non-magnetic substrate 1 plated with 1-2 was polished to make it smooth, and further textured and washed with a tape and abrasive grains. After that, the degree of vacuum is about 3.0 ×
Introducing the textured and cleaned substrate 1 into the substrate preparation chamber 7 of the DC magnetron type sputtering apparatus having the oxide film layer formation chamber exhausted to 10 to ⁷ Torr or less,
Next, it was heated to 280 ° C. by the heater 14 in the heating chamber 8. The substrate 1 is conveyed to the underlayer forming chamber 9 and the Cr underlayer 2 is moved to the substrate temperature: 270 by the sputtering cathode 15.
A film having a thickness of 500Å was formed at a temperature of ℃ and Ar gas pressure of 3 mTorr. Next, the magnetic recording layer is transferred to the magnetic recording layer forming chamber 10 and the CoCrTa magnetic recording layer 3 having a thickness of 2 is formed by the sputtering cathode 16 at a substrate temperature of 270 ° C. and an Ar gas pressure of 3 mTorr.
A film of 60 Å was formed. Then, it was introduced into the oxide film layer forming chamber 11. Here, as shown in FIG. 3, a gas mixed with oxygen at a rate of 10 to 100% with respect to Ar is introduced from the oxide film layer forming gas introduction port 19 and is simultaneously exhausted from the exhaust port 20 so that the gas pressure is 20 Torr. Then, the oxide film layer 4 was formed by keeping the equilibrium state for 10 seconds and holding the medium having the CoCrTa magnetic recording layer 3 formed therein for 10 seconds. Then, the carbon film layer 5 is transferred to the protective film layer forming chamber 12 and the carbon film layer 5 is heated to a substrate temperature of 2
A film having a thickness of 150 Å was formed at 50 ° C. and an Ar gas pressure of 4 mTorr, and the film was taken out from the substrate taking-out chamber 13. After lowering the room temperature, tape cleaning is performed and a fluorocarbon lubricating layer 6 of 30 liter is provided. 14-17 were created. This oxide layer 4 is formed by using X-ray photoelectron spectroscopy (ESCA).
The thickness was measured and found to be 2 to 5Å. Sample N
o. Table 1 shows the relationship between the above and each condition.

The sample (N
o. 1 to 17), the change in the number of defects when held for 120 hours under the conditions of a temperature of 60 ° C. and a humidity of 80% is represented by He
It was examined by using a magnetic disk surface inspection device by a method of detecting scattered light when -Ne laser light (6328Å) was incident. 4 to 7 show the result of this defect inspection. FIG. 4 shows Example 1 (Sample Nos. 1 to 3), Comparative Example 1 (Samples Nos. 10 and 11) and Comparative Example 2 (N
o. 12 and 13) show the defect inspection results. In the case of Comparative Example 1 having no oxide film layer, the carbon film 6 has a film thickness of 150Å. In No. 10, the number of defects increased to more than 200, and the carbon film 6 had a film thickness of 400 Å Sample N
o. Even 11 increases to 80. As a result of qualitative analysis of this defect arbitrarily selected by an energy dispersive X-ray fluorescence spectrometer (EDX), it was confirmed that it was a Ni, Cr, Co precipitate and a corrosion product. On the other hand, Example 1
Sample No. Nos. 1, 2, 3 and No. 2 of Comparative Example 2. 1
In Nos. 2 and 13, the number of defects increases only up to about 25, and the corrosion resistance of the medium can be improved by providing the oxide film layer 4 on the magnetic recording layer 3 by reactive sputtering of Ar: oxygen = 50: 50. it is obvious. In particular, sample No. with film thickness of 25 Å or more 3, 12, 13 has particularly stable corrosion resistance,
There is little difference between these.

FIG. 5 shows Example 2 (Sample Nos. 4 to 6).
3 is a defect inspection result of Comparative Example 1 (Sample Nos. 10 and 11). Stable corrosion resistance was obtained for Nos. 4, 5 and 6.

FIG. 6 shows Example 3 (Sample Nos. 7 to 9).
And the defect inspection results of Comparative Example 1 (Sample Nos. 10 and 11). Samples Nos. 7, 8 and 9 of Sample No. 1 of Comparative Example 1 in which the number of defects is about 80 or less and the corrosion resistance is inferior to those in Examples 1 and 2, but the oxide film layer 4 is not provided and the carbon film is 400 Å. It was confirmed that the corrosion resistance was improved by providing the oxide film layer 4 as well.

From the above, it is understood that when the oxide film layer 4 is formed by the method of Examples 1 to 3, a stable oxide film layer 4 can be obtained by setting the oxygen partial pressure to about 50% or more. . However, even if it is 50% or less, since the number of defects can be increased and reduced, the corrosion resistance is improved.

FIG. 7 shows Example 4 (Sample Nos. 14 to 1).
7) shows the defect inspection results of Comparative Example 1 (Sample Nos. 10 and 11). According to this, the sample No. with an oxygen partial pressure of 25% or more in Example 4 in which the oxide film layer 4 was formed by holding it in an oxygen atmosphere having a partial pressure of 25% or more. 15, 1
It is clear that the number of defects of 6 and 17 is about 40 or less and the corrosion resistance is improved stably. Sample No. with oxygen partial pressure of 10%. Sample No. 14 of the comparative example in which the number of defects increased to about 150 and the oxide film layer 4 was not formed and the carbon film was 100 Å. Although the corrosion resistance is better than 10, it is not a significant improvement. Therefore, it is understood that when forming the oxide film layer 4 by the method of Example 4, a stable oxide film layer 4 can be obtained by setting the oxygen partial pressure to 25% or more.

In the manufacturing method of the fourth embodiment, it is possible to use a mixing cylinder in which gas is mixed at a specific ratio in advance without providing each nozzle for introducing gas. Further, if the holding time is longer than a certain length, a stable oxide film layer can be formed. Therefore, if the tact time permits, it may be 10 seconds or longer, and in that case, the oxygen partial pressure may be lowered.

Further, using a vibrating sample magnetometer (VSM), the sample No. Table 2 shows the results of measuring the magnetostatic properties of Nos. 1 to 17.

[0034]

[Table 2]

Sample Nos. Of Examples 1, 2, 3 and 4
1-9 and 14-17 showed the coercive force which is not significantly different from the comparative example 1. However, the sample No. 12, 1
3 had a low coercive force. From this, the issue is how thin the oxide film layer 4 can exhibit corrosion resistance, and even if the oxide film layer 4 is formed to a thickness of 25 Å or more, the corrosion resistance is not impaired, but at a film thickness of 25 Å or more, the magnetostatic characteristics It is found that the above-mentioned influence is adversely affected, which hinders high-density recording.
Therefore, as shown in FIG. Although there is almost no difference between Nos. 3, 12, and 13, sample No. 12, 13
Is the sample No. Disadvantageous than 3.

The substrate is not limited to the aluminum alloy, and glass, ceramics, etc. can be applied. Other materials can be applied to the Cr underlayer.
It may not be necessary. The Co alloy used for the magnetic recording layer 3 is C
Not limited to oCrTa, CoNiCr or C
oCrPt or the like may be used. The method of forming the carbon film is not limited to the DC sputtering method, and the RF sputtering method or the CVD method may be used.

[0037]

As described above, the surface of the magnetic recording layer, which is in contact with the protective film layer, is uniformly oxidized to have a film thickness of 25 Å or less, so that the magnetic recording medium is excellent in corrosion resistance and capable of achieving high recording density. Can be obtained.

[Brief description of drawings]

FIG. 1 is a sectional view of a magnetic recording medium according to an embodiment of the present invention.

FIG. 2 is a schematic view of a DC sputtering film forming apparatus having an oxide film layer forming chamber used in another embodiment of the present invention.

FIG. 3 is a schematic view showing an oxide film layer forming chamber used in another embodiment of the present invention.

FIG. 4 is a diagram showing the defect inspection results of Example 1 and Comparative Example 1.

FIG. 5 is a diagram showing the defect inspection results of Example 2 and Comparative Example 1.

FIG. 6 is a diagram showing the defect inspection results of Example 3 and Comparative Example 1.

FIG. 7 is a diagram showing the defect inspection results of Example 4 and Comparative Example 1.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Substrate 1-1 ... Al alloy base 1-2 ... Ni-P plating layer 2 ... Underlayer 3 ... Magnetic recording layer 4 ... Oxide film layer 5 ... Carbon film layer 6 ... Lubrication layer 7 ... Substrate preparation chamber 8 ... Heating Chamber 9 ... Underlayer formation chamber 10 ... Magnetic recording layer formation chamber 11 ... Oxide film layer formation chamber 12 ... Carbon film formation chamber 13 ... Substrate extraction chamber 14 ... Heater 15, 16, 17 ... Sputtering cathode 18 ... Oxide film formation gas Inlet port 19 ... Exhaust port

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Akira Kato 2880 Kokufu, Odawara City, Kanagawa Stock Company, Hitachi Ltd. Storage Systems Division

Claims (5)

[Claims] 1. A magnetic recording layer is formed on a substrate, and a metal oxide film layer is formed on the magnetic recording layer in which at least one of the metal elements constituting the magnetic recording layer is oxidized. A magnetic recording medium, wherein a protective film layer containing carbon as a main component is formed on the film layer, and the thickness of the metal oxide film layer is 25 Å or less. 2. A magnetic recording layer is formed on a substrate by performing sputtering in a sputtering gas atmosphere of at least one of Ne, Ar, Kr, and Xe, and the sputtering gas atmosphere is continuously formed after the magnetic recording layer is formed. 50 by partial pressure inside
% Oxygen or more to oxidize at least one of the metal elements constituting the magnetic recording layer to form a metal oxide film layer, and further to form a protective film layer containing carbon as a main component. A method of manufacturing a magnetic recording medium, comprising: 3. A magnetic recording layer is formed on a substrate by sputtering in a gas atmosphere of at least one of Ne, Ar, Kr, and Xe, and the magnetic recording medium is placed in an oxygen atmosphere after the magnetic recording layer is formed. By holding for a certain period of time, at least one of the metal elements constituting the magnetic recording layer is
A method for manufacturing a magnetic recording medium, comprising the steps of oxidizing an element to form a metal oxide film layer and further forming a protective film layer containing carbon as a main component. 4. The method of manufacturing a magnetic recording medium according to claim 3, wherein the oxygen atmosphere is made up of oxygen at a partial pressure of 25% or more. 5. A magnetic disk drive using the magnetic recording medium according to claim 1.