JPH0444640A - Stationary magnetic disk and production thereof - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a fixed magnetic disk using a magnetic recording medium thin film material with excellent environmental resistance that enables high-density magnetic recording, and a method for manufacturing the same.

BACKGROUND OF THE INVENTION Magnetic recording media are currently widely used as tape-shaped media such as audio tapes and video recorder tapes, or disk-shaped media such as floppy disks and fixed magnetic disks. In recent years, there has been an increasing demand for higher recording densities in response to advanced information processing. In particular, fixed magnetic disk drives used in computer peripherals are increasing in capacity and becoming smaller year by year, and as a result, the fixed magnetic disks used in fixed magnetic disk drives are also becoming higher in density and smaller. Ta. Due to the demand for higher density, the recording medium materials used for fixed magnetic disks have also changed. The magnetic recording media that have been used in the past have changed to coated media, which are made by coating needle-shaped magnetic powder together with an organic binder, and now they are coated with organic binders on a disk substrate by means such as plating or vacuum sputtering. Thin film media manufactured by directly forming a magnetic film without a binder have appeared and become popular. Specifically, instead of a coated fixed magnetic disk in which gamma iron oxide acicular magnetic powder is coated on a conventional aluminum disk substrate, Co-Ni/C
Fixed magnetic disks made of r-alloy thin films have come into widespread use. Here, the current Co-Ni/Cr alloy Ti
1W1. As an example of a fixed magnetic disk using vacuum sputtering, we will discuss the structure and manufacturing method of a thin film fixed magnetic disk using the vacuum sputtering method. First, a mirror-polished aluminum disk is prepared as a disk substrate. An approximately 20 μm N1-P film is formed on this surface by plating.

Next, the surface is borinyu. At this time, after texture was applied to the surface, a Cry film of approximately 0.1 μm was formed by vacuum sputtering, and a Co-Ni thin H (approximately 0.0
．． 08pm or less).゛Here, Co of the magnetic layer
-Ni thin films have problems with corrosion resistance such as oxidation if left as is, so in order to improve corrosion resistance, we used the same vacuum sputtering method to
O□ or a protective film N such as amorphous carbon (approximately 5
00-800 people). Furthermore, a coating layer of lubricant (approximately 100 to 500 people) is formed on the surface of the Co.
- A fixed magnetic disk of Ni/Cr alloy thin film is completed.

In other words, the structure of the Co-Ni/Cr alloy thin film fixed magnetic disk is a six-layer structure of "lubricating layer/protective layer/Co-Nj alloy magnetic layer/Cr layer/Ni-P plating layer/aluminum substrate". There is. Furthermore, the composition of the Co-Ni/Cr alloy thin film used as the magnetic layer has been changed in order to reduce the effects of the demagnetizing field of the medium in order to stabilize the recording signal in short wavelength recording that corresponds to high density recording. As a result, the coercive force Hc of the medium is becoming higher.

In addition, in order to increase the storage capacity of a fixed magnetic disk, loss of head output due to the distance from the magnetic film to the magnetic head, that is, spacing (spacing loss)
In order to reduce this, it is extremely effective to reduce the running height (flying hide) of the magnetic head as much as possible. To lower the flying hide, the substrate must have excellent smoothness to prevent the magnetic head from crashing. Conventional disk substrates have mostly been made of aluminum. However, aluminum substrates have a limited processing accuracy for obtaining surface smoothness, and it has been difficult to improve the smoothness. From a material standpoint, glass substrates are increasingly considered to be effective because they have a smoother surface.

On the other hand, research is also being conducted on the principles of magnetic recording methods to increase the density. In the conventional longitudinal magnetic recording method (longitudinal magnetic recording method), as the recording wavelength is shortened for high-density recording, recording becomes difficult due to the influence of the Kl field due to the recording principle.

Perpendicular magnetic recording has been developed as a high-density recording method that overcomes this drawback. Against this background, thin-film perpendicular magnetic recording media are attracting attention today as a magnetic recording medium that is most compatible with high-density recording.

Currently, this type of media is not compatible with fixed magnetic disks on which magnetic heads fly and run, but instead records are made with the magnetic head in contact with the medium.

Perpendicular magnetic recording media of co-Cr alloy thin films are being actively researched.

As mentioned above, Co--Ni/cr alloy thin film fixed magnetic disks on aluminum substrates have been manufactured and are becoming popular as fixed magnetic disks compatible with high-density recording. and,
As fixed magnetic disks enable even higher density recording, the flying hide of magnetic heads is becoming smaller and smaller in order to reduce the spacing loss of the head output. Recently, 0.05 to 0.1 μm (500 to 1
Head running with a flying hide amount of about 1,000 people is also required.

The invention solves the problem: However, the magnetic layer of the disk described in "-" is CON+,
Since it is a thin Qr base metal film, there is a problem of deterioration due to oxidation, etc., and a protective film layer is required to improve corrosion resistance. A protective film layer is provided on the surface (L: 1)
Therefore, even if the fly-gheight becomes smaller, magnetically the distance between the magnetic recording medium (magnetic layer) and the magnetic head is
The area would be 7 times larger than the protective layer (approximately 500 to 800 people), and the spacing loss would increase accordingly, making it difficult to support higher density. Also 1- As mentioned above, Co
-Ni/Cr alloy thin film fixed magnetic disks require a protective film layer and have a multi-layer structure, which complicates the manufacturing process.
It has been desired to manufacture fixed magnetic disks in a simple manner.

Fixed magnetic disks using perpendicular magnetic recording horn-type C○Cr-containing Cr-air recording media materials, which are attracting attention as materials capable of supporting even higher recording densities, are also considered desirable in the future. However, the Co-Cr alloy thin film medium described in 1. There were drawbacks such as scratches and pitting due to the sliding movement of the magnetic head.

In addition, like the Co Ni/Cr alloy thin film, the C,o-Cr alloy thin film is a metallic thin film, so there is a problem in its corrosion resistance against oxidation, etc. However, there was a major challenge in ensuring reliability, such as improving bathware durability and corrosion resistance.

Various efforts have been made to solve this problem.

For one thing, a method was devised to provide a protective layer (JW) on the surface of a Co-Cr thin film. , to ppl 1986, 248). Also C
A method of providing a protective layer of cobalt oxide on the surface of the o-Cr thin film has also been proposed.

As described above, efforts are being made to improve the reliability of bathware durability and corrosion resistance by forming a film on the surface of a Co--Cr alloy thin film medium. However, the aforementioned Co-
As in the case of the Ni/Cr alloy yi film membrane, in terms of 3-dimensional recording, a protective film layer is inserted between the magnetic recording medium and the magnetic head, so the flying height is small, but the magnetic -..., since the actual spacing between the grooved media increases, it is not necessarily the best method for high-density recording.Furthermore, the formation of a protective film increases the manufacturing time of the media, There is also the issue of complicating things and getting complicated.

The present invention is intended to solve the above-mentioned problems, and aims to provide a fixed magnetic disk without a protective film layer and a method for manufacturing the same.

In order to achieve the objective of solving the problem, the present invention provides a disk made of an alloy thread (metallic) magnetic thin film medium material 1 which requires a conventional protective film layer, Compatible with high-density magnetic recording Capacity: It has a perpendicular magnetic recording component, has a plate-shaped structure, has a spinel-type crystal structure, and has a chemical composition of iron and cobalt. Using media material $1,
The medium thin film is formed on a glass substrate-1-, and the fixed magnetic disk has a film structure with a lubricant layer formed on its surface. The glass disk substrate is manufactured through step J, step 7 of forming a yi film of oxide magnetic recording material by Blaze 7 excitation MO-CVD method, and forming a lubricant layer by lubricant layer-7i. .

The present inventors have hitherto developed Buchsma-excited M
It was discovered that by using the O-CVD method, it was possible to obtain perpendicularly magnetized Ti1VIIJ consisting only of a spinel-type oxide magnetic material with a shape in which fine columnar particles grew densely on a ground substrate (Fujiga et al. Eishi et al. Japanese Society of Applied Magnetics u゛, 12th
Volume, 339 pages (1988) and JP-A-63-1
81305).

The thus obtained lumbar material is an oxide material having the same spinel-type crystal structure as a magnetic ceramic material generally called ferrite. Since ferrite is an oxide ceramic, it is a material that not only has excellent oxidation resistance but also excellent environmental resistance, and is also a material with high hardness. Therefore, the spinel type oxide used in the present invention The magnetic recording medium thin film also has excellent oxidation resistance, environmental resistance, and abrasion resistance.

Therefore, when used as a fixed magnetic disk, there is no need for a protective film layer for the purpose of protecting the magnetic thin film, which is required with conventional alloy-based magnetic recording medium thin film materials in terms of film structure.
By making the flying hide smaller to support high-density recording, it is possible to directly and effectively reduce the spacing between the traveling magnetic head and the thin film of the magnetic recording medium, resulting in loss of head output due to spacing. (spacing loss) will be significantly reduced, allowing for a fixed magnetic disk with a larger capacity.

Furthermore, the film structure of the fixed magnetic disk becomes simpler.

Further, since the magnetic recording medium thin film used in the present invention has a perpendicular magnetization component, the influence of a demagnetizing field can be reduced even on short wavelength recording for high-density recording.

Furthermore, by using the plasma-enhanced MO-CVD method, the above-mentioned oxide magnetic thin film can be formed regardless of the type of underlying substrate, so it is easy to form the above-mentioned oxide thin film directly on a glass disk substrate. I can do it. Therefore, as mentioned above, compared to the conventional fixed magnetic disk made of alloy magnetic material which has a complicated film structure (six-layer structure), it has a three-layer structure of "lubrication layer / oxide magnetic thin film layer / glass substrate" which has a much simpler film structure. The structure will be a magnetic disk.

In addition, the present inventors previously discovered a method for producing a disk-shaped glass substrate by press-molding a glass material lump using a pair of press dies while heating it (for example, Japanese Patent Laid-Open No. 62-100429 Publication No. 1) A glass disk substrate for use in the fixed magnetic disk of the present invention is prepared by heating a glass material lump and press-molding it while heating using a pair of press molds, and the disk substrate is produced as it is. By using a process in which the above-mentioned magnetic thin film is formed on the top by plasma-enhanced MO-CVD method, and a lubricant is further applied to the surface to form a lubricant layer,
Compared to the conventional method of manufacturing fixed magnetic disks made of alloy magnetic materials, typified by Co--Ni/Cr alloy magnetic disks, this method requires significantly fewer steps.

Example Hereinafter, the present invention will be explained in detail using examples.

First, a glass disk substrate for a magnetic disk was manufactured using a press molding method in the following manner.

! Tungsten carbide with a diameter of 98 m and a height of 30 mm (
WC) [Composition; WC/Co/Cr8c2=91/8/1
(wt%)] was prepared, one bottom surface was mirror-polished, and a platinum-iridium alloy film with a thickness of 3 μm was formed using a high-frequency sputtering device. The membrane surface was mirror-finished. Two platinum-iridium alloy coated tungsten carbide sintered blocks having mirror-finished surfaces prepared in this way were prepared. A pair of press molds consisting of two platinum-iridium alloy-coated tungsten carbide sintered blocks with mirror-finished surfaces were prepared.

The pair of press molds 1.2 were set in the press machine shown in Fig. 1, heated to 600°C, and the composition was 268 wt% Sin, 208 wt% B20. ] 1
1wt%, Ba02wt%.

Raw material optical glass disk containing 2010 wt% Na (diameter 95.
3) was placed between a pair of molds heated to 700°C, and the pressure was 2 kg-cm. After holding the mold for 2 minutes with a gap of 1.20- between a pair of molds placed above and below, the disk-shaped glass material was cooled to 450°C for 10 minutes while being sandwiched between the molds. The glass disk was taken out.

In Fig. 1, 4 and 5 are heaters for heating the press mold 1.2, 6 is a raw glass disc supply jig, 7 is a piston cylinder for the upper mold, 8 is a piston cylinder for the lower mold, and 9 is a raw glass circle. In the plate preheating tunnel furnace, 10 is a molded disk outlet. In this way, a donut-shaped glass disk substrate with a hole in the center for mounting the rotating shaft was fabricated.

On one side of the prepared glass disk substrate, 52
An oxide magnetic recording medium f13 thin bamboo film was formed to a thickness of 2,500 mm using the Gonzma-excited MO-CvI method.

Figure 2 is a small-sized diagram of the configuration of the plasma-enhanced MOCVD apparatus used for film formation. This plasma excitation M O-CV D
The device generates plasma by high frequency between one of the earth side electrode 14 and the RF side electrode 15 arranged in parallel in the vacuum chamber 17, decomposes the organometallic raw material gas in the plasma, and transfers it to the substrate J-. This is an apparatus that forms an Fjl film by chemical monitoring (CVl). The prepared Gaussian disk substrate 11 was held with one side in close contact with the ground side electrode 14, and the substrate was heated and held at a preheated temperature of 400°C by means of a heater 12. ``Power, origin
1 vaporization vessel 20 and 20', respectively, iron (1't')acetylacell-1~=1・24 and Kobal), (I[l>
Add acetylacetonate 25, oil lotus 19.1
9' to 135°C and 125°C, respectively.

Heating (, , , ■) vaporized each 7 sedile acetonate, carrier gas (nitrogen) 1
8.18' (each l0rnffi/m1n)4
Using this, a flow was introduced into the vacuum jar 17'.

On the other hand, 15 m7 of oxygen gas 21 was used as a reactive gas! /+n
On the way in, there was a ``mixture'' and a blowout appeared in the river 7.

It was poured from nozzle 23 and put in. At this time, the vacuum (exhaust L in the Yanhar 17) and the vacuum sliding J from 22 are 0.0
The vacuum level was maintained at 5rnTorr. Next, create a magnetic field between the earth side electrode 14 and the RF side electrode 15 using 1.
By applying 0 W of high frequency ε (every 4 minutes), plasma is generated between the ground side electrode 14 and a magnetic thin film of oxide is formed on the surface of the glass disk Mil+. In this example, the glass disk substrate 11 was rotated at a speed of 120 rpm using a substrate rotation motor 13.

The glass disk substrate on which the magnetic f# film was formed was taken out from the vacuum chamber 2, and the same magnetic thin film was formed on the back glass surface by plasma-excited MO-CVD in the same manner. We fabricated a disk with a magnetic thin film surface.

Next, this disk was submerged in a liquid tank ζ containing a sonosystemic organic lubricant and a lubricant was applied to it. was created.

The manufactured fixed magnetic disk of the present invention has a Gisenbu length (,
G L ) is (11, 25 μm11, trough convergence (T
%V) is 1877m, + Yump Debs (GD) is 3. O
Use a MIG head' with 30 turns of coil at ltm, 50 mAc7)...Select the nodal current value λ, and evaluate the electromagnetic conversion characteristics. Fixed magnetic disk is 3600
Rotate at a speed of rpm, 25.0 from the center of the disc.
The evaluation was performed using a circle of mm (1'6T). At this time, the relative speed between the fixed magnetic disk and the magnetic head is 9.4 m/sec, and 1. Magnetic Henodo's Flying High 1
was 0.10 μm. The relationship between the reproduction output and the recording frequency of the fixed magnetic disk of the present invention obtained through this evaluation is shown in FIG. 3. In addition, this fixed magnetic disk has 50
(When observing the reproduced waveform of the recorded signal at 3kl (, -) with an orthot7 scope, it was found that the dipulse waveform, which is characterized by containing the perpendicular magnetic recording d component, was reduced.

After measuring the electromagnetic characteristics of the fixed magnetic disk of the present invention, the lubricating film layer is removed using acetone and ethyl ether.
j) No crystal structure analysis by magnetic measurement and X-ray diffraction;
Furthermore, the disk was broken and the surface and fractured surface of the magnetic thin film were observed using a high-resolution 8-scan electron microscope. We also analyzed the chemical composition of the magnetic A4 film using chemical analysis. From the magnetic measurement results, the fixed magnetic disk of the present invention has a coercive force Hc of the perpendicular magnetization component of 1200.
0e, and the coercive force Hc of the in-plane magnetization component is 8000
It was e. Also, the saturation magnetization IMs is 250 emu/ec
Met. X-ray diffraction showed that the magnetic thin film was composed only of iron-based oxides with a spinel crystal structure.

Also, from the conclusion V of the chemical analysis, the molar ratio of iron and Kohar 1 is F
e: It was found to be Co-.93 near. That is, the ruptureable Fil film has a spinel crystal structure F ez,qt
Only oxides with compositions such as lc Oo and ozOa can be found.1. Ta. In addition, observation using a scanning electron microscope revealed that the magnetic Til film has a columnar structure in which columnar particles with a diameter of 300 to 600 are densely gathered against the glass disk substrate. I understand.

For comparison, a magnetic film thickness of 800 mm (0,
08μm) and a carbon film of 600μm as a protective layer on top of it.
A conventional Co-Ni/Cr alloy thin film fixed magnetic disk (aluminum substrate with magnetization oriented in-plane) prepared by forming a magnet and provided with a lubricant coating layer similar to the present invention was prepared, and the fixed magnetic disk of the present invention was prepared. The same electromagnetic conversion characteristics were evaluated under the same conditions as for magnetic disks. The above Co obtained by this evaluation
FIG. 3 shows the relationship between the reproduction output and the recording frequency of a fixed magnetic disk made of a -N i /Cr alloy 'rll film.

In addition, the reproduced waveform of the recording signal of this disc at 500 kHz was observed. Unlike the disk of the present invention, no gui pulse waveform was observed, and it was confirmed that this Co--Ni/Cr alloy thin film fixed magnetic disk was a disk consisting of a longitudinal magnetic recording component.

From FIG. 3, it can be seen that although the fixed magnetic disk of the present invention has a smaller saturation magnetization value of the magnetic thin film than the Co-Ni/Cr alloy thin film, the reproduction output shows almost the same value. However, on the high recording density side in the shorter wavelength range, Co
It can be seen that the reproduction output is higher than that of the -Ni/Cr alloy thin film disc. In other words, it was found that the fixed magnetic disk of the present invention can support high-density recording. In the above example, a columnar structure thin film of a magnetic oxide with a spinel-type crystal structure consisting only of iron and cobalt was used as the magnetic thin film used in the disk, but of course various thin films having the same form and showing similar magnetic properties can be used. If it is an iron-cohard spinel type oxide thin film containing added ions,
Similar characteristics can be expected as a fixed magnetic disk.

Effects of the Invention As described above, the film-structured fixed magnetic disk of the present invention has a shorter flying height than the conventional alloy-based fixed magnetic disk when the flying height of the magnetic head is reduced. Even in the wavelength range, a descending head output can be obtained, making it possible to support higher density recording and larger capacity fixed magnetic disk drives. Furthermore, the membrane structure is three layers, which is simpler than the conventional six-layer structure, and the manufacturing method of the present invention can significantly shorten the manufacturing process.

In other words, since it can be manufactured with fewer steps, fixed magnetic disks that can handle high-density recording can be supplied at lower cost than in the past.

[Brief explanation of the drawing]

Fig. 1 is a schematic configuration diagram of a glass press machine used in an example of the present invention, Fig. 2 is a schematic cross-sectional front view of a plasma-excited MO-CVD apparatus used for manufacturing a magnetic oxide El film, and Fig. 3 1 is a comparison diagram of reproduction output characteristics by magnetic heads of the present invention and fixed magnetic disks for comparison. 1.2...Press mold, 3...Raw material optical glass disk, 4.5...Press mold heater,
7..Piston cylinder for upper mold, 8..
・Lower mold piston cylinder, 11... Glass disk substrate, 12... Self... Substrate heating heater, 14...
...Ground side electrode, 15...RF (Ij
Electrode, ...Oxygen gas, 2-iron acetylacetylacetoner

Claims (4)

[Claims] (1) Columnar-shaped particles stand perpendicularly to the surface of the glass disk substrate on the glass disk substrate, and form a columnar structure film in which they are densely aggregated to form a film, which has a spinel-type crystal structure as determined by X-ray diffraction. A fixed magnetic disk that has a magnetic oxide thin film made of an oxide containing iron and cobalt, and a lubricant coated on top of the magnetic oxide thin film to form a lubricating thin film layer. (2) The magnetic oxide thin film is a thin film formed by a plasma-enhanced MO-CVD method in which a mixed gas of organometallic compound vapor and oxygen is deposited by chemical vapor deposition in plasma. Fixed magnetic disk. (3) The fixed magnetic disk according to claim (1), wherein the glass disk substrate is a disk-shaped glass substrate manufactured by heating and press-molding a glass material. (4) A fixed magnetic disk is manufactured through the step of manufacturing a glass disk substrate using a glass press molding method, followed by the step of forming a magnetic oxide thin film using a plasma-enhanced MO-CVD method, and then the step of forming a lubricating thin film layer. A method for manufacturing a fixed magnetic disk.