JPH038119A - Production of magnetic recording medium - Google Patents

Abstract

PURPOSE:To obtain a magnetic recording medium having extremely high coercive force by incorporating a specified amt. of water into a rare gas atmosphere at low pressure in the process of forming a Cr base thin film layer on a substrate. CONSTITUTION:A specified amt. of water is incorporated into the rare gas atmosphere at low pressure in the process of forming a Cr base thin film layer on a substrate. The amt. of water incorporated into the rare gas is determined to satisfy the partial pressure of water of >=1 X 10<-5>Torr, and preferably 1 X10<-5> - 1 X 10<-3>Torr, and more preferably, 2 X 10<-5> - 1 X 10<-3>Torr. If the partial pressure of water in the forming process is <1 X 10<-5>Torr, coercive force of the obtd. medium can not be improved enough. The rare gas is Ar, He, Ne, Kr, Xe, etc., and it is particularly preferable to use Ar.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Application on A Beam] The present invention relates to a method of manufacturing a magnetic recording medium, and more particularly, to a method of manufacturing a magnetic recording medium having a high coercive force.

[Background Art] In recent years, with the development of information processing technology for computers and the like, there has been an increasing demand for higher density recording in magnetic recording media such as magnetic disks used in external storage devices.

Currently, the magnetic layer of magnetic recording media used for longitudinal recording magnetic disks is made of chromium (
Cobalt (CO) based alloy thin films epitaxially formed on Cr) base thin films have become mainstream. However, this Co-based alloy thin film magnetic layer also needs to have higher coercive force as a magnetic property to meet the demand for high-density recording, and there have been no reports on this property. , many have been done.

(For example, 'New longitudinal re
coding mediaCoxNi, Cr, f
rom high rate 5tatic magn
etron sputter-ing system” I
EEE Trans, Magn, Mag-22°N
o5. (1986), 334; JP-A-63-7923
3; JP-A-83-79988) [Problems to be Solved by the Invention] As previously reported, the coercive force of a Co-based alloy thin film magnetic layer increases with the thickness of the Cr underlayer thin film. do. However, when a certain upper limit is exceeded, saturation characteristics are exhibited, and it is difficult to increase the coercive force further. For example, JP-A-63-7
No. 9968 discloses that the thickness of the Cr underlayer thin film is 1500 mm.
It has been shown that above A, there is a tendency for the coercive force of the magnetic layer to saturate and the coercive force of the magnetic layer does not increase any further, and below that, the coercive force of the magnetic layer decreases significantly, posing a practical problem.

Moreover, this coercive force increases as the thickness of the Co-based alloy thin film is reduced. However, since reducing the film thickness leads to a decrease in the reproduction output value, it is practically difficult to reduce the film thickness to a predetermined thickness or less. Further, although it is possible to improve the coercive force to some extent by selecting sputtering conditions such as the deposition gas pressure and substrate temperature during deposition of the magnetic layer, the improvement effect is small.

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned conventional problems and provide a method for manufacturing a magnetic recording medium having an extremely high coercive force.

[Means for Solving the Problems] The method for manufacturing a magnetic recording medium of the present invention is a method for manufacturing a magnetic recording medium in which a Cr underlayer thin film and a Co-based alloy magnetic thin film are sequentially laminated on a substrate. When forming a base layer thin film in a low-pressure rare gas atmosphere, water is added to the rare gas.
It is characterized in that the film is formed by coexisting at a partial pressure of Xl0'''torr or more.

That is, in view of the above-mentioned conventional situation, the present inventors have conducted intensive studies to further improve the retention force of Efi gas recording media, and as a result, they have developed a method for forming a thin Cr underlayer film on a substrate in a low-pressure rare gas atmosphere. When forming a film with the rare gas coexisting with a specific amount of water, Co is further added onto the Cr underlayer thin film.
The present inventors have discovered that the coercive force of a magnetic recording medium obtained by forming a magnetic thin film of a based alloy is significantly improved, and has completed the present invention.

Hereinafter, the present invention will be explained in detail.

The substrate used in the present invention generally includes hard glass,
A disk-shaped substrate made of aluminum or an aluminum alloy is used, and an aluminum substrate is particularly preferably used. Aluminum substrates are usually processed to a predetermined thickness, and after mirror-finishing the surface, a hard non-6N metal such as a nickel-phosphorus (Ni-P) alloy is applied as a first underlayer by electroless plating or anodizing. After that, a Cr film is formed and used as a second underlayer. Note that the above-mentioned first underlayer is not necessarily required, and a Cr film may be formed directly on the mirror-finished aluminum substrate as the underlayer.

The present invention is characterized in that when forming a Cr underlayer thin film on the above-mentioned substrate in a low-pressure rare gas atmosphere, the film is formed in the presence of a specific amount of moisture (H2O) in the rare gas. It is. The coexistence amount of water in the rare gas is 1 x 1 O-5 torr or more, preferably l
It is in the range of Xl0-' to 1xlO-3 torr, more preferably in the range of 2x10-5 to lXl0-'torr. If the water partial pressure at the time of film formation is less than 1xlO"5 torr, it is not preferable because the effect of improving the coercive force of the obtained magnetic recording medium will not be sufficiently obtained. If water with such a water partial pressure is contained in a rare gas, it is not preferable. There are no particular restrictions on how they can coexist;
Various methods can be adopted. For example, it is a desirable method to introduce the noble gas into the film forming apparatus while moistened with wood.

Further, the film forming method is not particularly limited as long as it is a method of forming a film in a low pressure rare gas atmosphere after evacuation, but generally a vacuum evaporation method, a sputtering method, an ion blating method, etc. can be adopted. Among these, sputtering method is particularly preferably used. Note that examples of the rare gas include argon, helium, neon, krypton, and xenon, and argon (Ar) is particularly preferably used.

Hereinafter, the case where the sputtering method is used to form the Cr underlayer thin film will be described in detail.

As the sputtering method, it is possible to use all the equipment and conditions that are normally employed when forming a Cr underlayer thin film on the substrate by the sputtering method. For example, with the substrate mounted on the substrate holder and the Cr target electrode facing each other, the ultimate pressure in the evacuated chamber should be set to 1Xl0-6 torr or less, and the film forming pressure, i.e., the pressure of a rare gas such as Ar containing moisture ( Total pressure of rare gas + moisture) from 5X 10-' to 2X 10-2 tor
r, preferably 1 x 10-3 to I x 10-2t
o r r range, water partial pressure 1xlO-5torr
Above, preferably l x 10-'' to l x 10-'
tor r, more preferably 2X 10-5 to IX
A thin Cr film is deposited on the substrate by sputtering at a substrate temperature of 150 DEG C. or higher, preferably 180 DEG to 300 DEG C., in a range of IO-'N orr. Note that the ratio of the water partial pressure to the total pressure of the rare gas and water is usually within the range of 0.1/+oo to 10/100, preferably 0.1/100 to 5/100.

As the sputtering device, a normal DC magnetron sputtering device, an RF magnetron sputtering device, or the like is employed.

The thickness of the Cr underlayer formed in this way is usually 5
It is preferably within the range of 0 to 3000A.

In the present invention, C formed on the Cr underlayer thin film of the substrate
As the o-based alloy bfi thin film, Co-Cr, Co-N
Co-based alloys represented by i, Co-Cr-X, Co-Nf-X, Co-W (tungsten)-X, etc. are used. In addition, here, X is lithium, silicon, calcium, and titanium.

vanadium, chromium, nickel, arsenic, yttrium,
Zirconium, niobium, molybdenum, ruthenium, rhodium, silver, antimony, hafnium, tantalum, tungsten, rhenium, osmium, iridium, platinum, gold, lanthanum, cerium, praseodymium, neodymium, promethium, samarium, europium. Or two or more kinds of elements can be mentioned.

The 1ift thin film layer made of these Co-based alloys is usually deposited on the Cr underlayer thin film of the substrate by means such as vacuum evaporation, ion blasting, sputtering, electroless plating, or the like.

A sputtering method is particularly suitable as a method for forming the Co-based alloy magnetic thin film.

In the sputtering method, C is generally applied on the base layer of the substrate.
When depositing the l1Ti thin film layer made of the o-based alloy by sputtering, it is possible to use all the equipment and conditions that are normally employed. For example, the ultimate pressure inside the evacuated chamber is lXl0-'torr
Below, the pressure of rare gas such as Ar is 5X10-' to 2X10-
2 torr, preferably lXl0-' to lXl0-2t
Sputtering is carried out under conditions where the substrate temperature is 150°C or higher, preferably 180 to 300°C.

As the sputtering device, a normal DC magnetron sputtering device, an RF magnetron sputtering device, or the like is employed.

In the present invention, the thickness of the Co-based alloy magnetic thin film layer is usually 2
It is suitable that it is within the range of 00 to 1500A.

[A 6f1 recording medium with an extremely high coercive force by further laminating a Co-based alloy magnetic thin film on the C underlayer thin film formed in a low-pressure rare gas atmosphere with a water partial pressure of 1X10-5 torr or higher. is obtained.

[Examples] The present invention will be explained in more detail by referring to Examples and Comparative Examples below, but the present invention is not limited to the following Examples unless it exceeds the gist thereof.

Examples 1 to 3, Comparative Example 1.2 Sputtering was performed under the conditions shown in Table 1 with a Cr target facing a disk-shaped substrate made of an aluminum alloy whose surface was plated with N1-P. A thin 1 (2oooA) Cr underlayer was deposited on the substrate. Next, using a Go-Ni-Cr alloy target, sputtering was performed under the conditions of a chamber pressure of 1X10-'' torr or less, a film forming pressure (argon pressure) of 4X10-'' torr, and a substrate temperature of 210°C. C07O-Nj20 Cr, on top of the formation.

(Numbers represent atomic percent.) Magnetic Thin 11i (640A
) was deposited. Br・δ (TA residual magnetic flux density (Br)
The thickness (δ) of the magnetic thin film layer) was 515 G·μm.

The coercive force of the obtained BN air disk was measured using a sample vibrating type 6FI force meter, and the results are shown in Table 1.

[Effects of the Invention] As detailed above, according to the method for manufacturing a magnetic recording medium of the present invention, a high-performance magnetic recording medium having a high coercive force can be easily manufactured, and a magnetic recording medium with even higher performance can be manufactured. Density recording is possible.

Claims (1)

[Claims] (1) In a method for manufacturing a magnetic recording medium in which a chromium underlayer thin film and a cobalt-based alloy magnetic thin film are sequentially laminated on a substrate, when forming a chromium underlayer thin film on a substrate in a low-pressure rare gas atmosphere, the rare gas Add 1×10＾-＾5torr of water to
1. A method for manufacturing a magnetic recording medium, characterized by forming a film at a partial pressure equal to or higher than r.