JPH02118916A - Magnetic recording medium - Google Patents

Abstract

PURPOSE:To decrease the frictional force and attraction force with a magnetic head and to improve durability by constituting the magnetic recording medium to be used for a magnetic disk device of a magnetic recording medium layer which is formed on a base, a protective layer which covers the recording medium layer and consists of silicon oxycarbide and a lubricating film which covers the protective layer. CONSTITUTION:An Ni-P or Ni-Cu-P layer is formed by plating on a substrate 1 consisting of an Al-Mg alloy to constitute an underlying layer 2. The surface is ground by a lapping tape to form the substrate having about 500Angstrom Rmax. of the substrate 1 and the underlying layer 2. The film of the magnetic recording medium 3 is then formed by a sputtering method, etc., thereon and the surface thereof is coated with a surface protective film 4 consisting of the silicon oxycarbide. The film 4 is formed to 500Angstrom thickness and further, the fluorine lubricating agent is applied thereon at need while the concn. thereof is adjusted to 1wt.%. The magnetic disk which obviates the generation of the degradation in the reproduced output against use for, for example, >=20,000 times of rotations, is obtd. in such a manner.

Description

[Detailed description of the invention]

[Industrial Field of Application] The present invention relates to a magnetic recording medium such as a magnetic disk used, for example, in a magnetic disk device. [Prior Art] In recent years, the importance of external storage devices such as magnetic disk devices in computer systems has increased, and the demand for high recording densities has increased considerably. A magnetic disk device is composed of a main component of a recording/reproducing head and a magnetic disk. The magnetic disk rotates at high speed, and the recording/reproducing head, that is, the magnetic head floats a minute distance above the magnetic disk. In order to increase the recording density and performance of magnetic disks, it is necessary to make the magnetic recording medium single-layered and uniform, improve the magnetic properties (improve the magnetic force and squareness ratio), and improve the magnetic head. Examples include low l/high. Up until now, magnetic disks have been manufactured by coating a mixture of a polymeric material such as a binder and γ-Fe203 magnetic recording medium particles. In this method, there is a limit W in making the magnetic recording medium thinner and more uniform. For this reason, agricultural companies have begun to form a continuous thin film on a magnetic recording medium by a method such as sputtering. γ-
An example of the configuration of a magnetic disk using an Fc201 continuous thin film medium is shown in FIG. FIG. 8 is a diagram showing a cross section of a thin film @ air disk reported in, for example, the Telephone and Telecommunications Public Corporation Research and Practical Application Report, Vol. 31, No. 9, pages 1731 to 1744. In the figure, (+) is a disk-shaped aluminum alloy substrate, (
2) is the underlayer of the magnetic recording medium layer made of alumite, (
3) is the γ-Fe203 thin film of the magnetic recording medium layer. Currently, @Ki disk drives use the contact start/stop (C3S) method in which the magnetic disk and magnetic head come into contact when starting and stopping; Rotate as it is. The frictional force generated between the magnetic head and the magnetic disk in this contact friction state wears out the surface of the magnetic head and the magnetic disk, and may eventually create a (U) on the magnetic head and magnetic recording medium film. When a continuous thin film is used, even a slight drop in the recording medium results in the loss of the recorded signal.This is a serious problem concerning the reliability of 1a as an external storage device for magnetic disk drives. Therefore, in order to protect the magnetic recording medium from contact friction and contact damage between the magnetic head and the magnetic recording medium, a 5102 film, a carbon film, and an Al2O3 film are coated on the surface of the magnetic disk.
It has been proposed to provide a protective film such as a film (for example, Akio Tago et al., 8th Japanese Society of Applied Magnetics, Abstracts of Academic Lectures (+984), p. 222; Yoshihiro Kimachi et al., 1985 IEICE) Proceedings of the General National Conference (1986), l-1
Page 66; Published in Hiroyasu Karimoto et al., Proceedings of the 30th Meishun Research Conference of the Japanese Society of Lubrication (1986), page 1. ), When the magnetic recording medium is metal, this protective film also serves as a protection to prevent corrosion of the metal film. On the other hand, efforts are being made to reduce the floating height of magnetic heads. Ensures stable head position at low flying height,
In order to prevent collisions (head crushes) between the FIL'X head and the magnetic disk, improvements in disk surface precision and improvements in head crush resistance are being considered. In particular, the improvement in disk surface precision is remarkable, and the Rma of conventional disks is
x used to be over 2000 Å, but now Rmax is around 100, which is more than an order of magnitude smaller. As the surface precision of disks improves year by year, problems have arisen in which the magnetic head is attracted to the surface of the magnetic disk, and even when the magnetic disk begins to rotate, the magnetic head cannot fly, causing damage to the magnetic head. , E. , M. Rossift
! ! , Journal of Applied Physics (J, Appl-Phys,) Volume 55, No. 6,
2254i). For this reason, methods have been considered such as applying fine powder to the surface of a substrate that has been finished like a -1 mirror surface, or re-polishing or etching it to form minute protrusions on the surface. -117735.6
0-38720.60-40528.61-29418
, see G1-203259.61-261820). [Problems to be Solved by the Invention] Forming a film from a solution is known as a simple method for providing an oxide film as a protective film. Heat treatment is performed when forming SiO2 films, Al2O3 films, etc. using the sol-gel method, etc., but heat treatment at a temperature below about 400°C that does not change the characteristics of the recording medium will not sufficiently vitrify it. However, it is considerably inferior in hardness and strength compared to ordinary ceramics (Masahiro Yanagisawa, Proceedings of the National Conference Commemorating the 30th Anniversary of the Founding of the Japanese Academy of Aging (1985), p. 45). For example, when synthesizing glass from metal alkoxide, the heat treatment temperature required to vitrify the gel obtained by hydrolyzing the metal alkoxide is 600 to 1000°C, and silica glass produced by the melting method exhibits the same properties as silica glass. 900-1000
It is said that this is the case when heat treatment is carried out to
), l.17-16.1). For this reason, the oxide film made from molten γtl was insufficient in both hardness and strength. In this regard, oxide films and carbon films formed by sputtering etc. can have superior strength compared to the above-mentioned sol-gel films (for example, Yoshihiro Honmachi et al.
Proceedings of the Annual National Conference of the Institute of Electronics and Communication Engineers (1986), l
-166 pages). However, in today's substrates that have minute protrusions on their surfaces, mechanical protective films such as 5iO2tlW, A, I2O3 films, and carbon films, as seen in many academic conference presentations, are difficult to use. It had the disadvantage of insufficient strength. That is, since the magnetic head comes into contact with the top of the minute protrusion, the protective film corresponding to the protrusion is fragile and is likely to break and be scraped off. Further, even if the loss 1k does not extend to the magnetic recording medium, a problem arises in that the minute protrusions on the surface disappear and the magnetic head is attracted to it, making it impossible for the magnetic head to fly. This invention was made to solve the above-mentioned problems, and it prevents damage to the magnetic recording medium caused by the magnetic head, prevents the separation of the protective film, and improves the magnetic recording medium of the magnetic head. The object of the present invention is to obtain a highly reliable magnetic recording medium. [Means for Solving Problems 5] In the magnetic recording medium according to the present invention, a protective film that covers and protects the magnetic recording medium layer is made of silicon oxide carbide (S l Ox
c 2-<). [Function] In the magnetic recording medium of the present invention, the protective film on the surface of the magnetic recording medium layer is made of a silicon oxide carbide (Sin.C2,...) film, and its durability is superior to that of conventional oxide films and carbon films. The magnetic recording medium is much stronger than the previous one, and the reliability of the magnetic recording medium is improved. [Example] Hereinafter, an example of the present invention will be described with reference to (4). substrate,
(2) is the T layer of the magnetic recording medium layer, and in this example, the J& material is composed of the AI-IJg alloy substrate (1) and the FIth layer (2). (3) is the magnetic recording medium layer, (z
1) is a film made of silicon oxide carbide (hereinafter referred to as silicon oxide carbide) (S1OtC2-0) film. Next, an example of a method for manufacturing the magnetic disk of this embodiment will be explained. First, the process up to the formation of the magnetic recording medium layer (3) will be simply explained. A lower layer (2) on the surface of the A I -Mg alloy substrate (+)
Using a Dave grinder, lapping tape W A # 6000, pressing force 1 was applied to a base material that had been coated with N1-P or N1-CIJ-P plating film and had a mirror finish.
kg, substrate rotation speed 20Orpm, tape feed speed 20
Texture processing was performed under the conditions of mm/min. As a result, a base material having an Rmax of about 500 people can be obtained. A magnetic recording medium was formed on this base material by sputtering. Next, an example of the silicon oxide carbide surface protective film (4) type n1 method and its preparation device will be described with reference to the drawings. No. 2 [4] is a configuration diagram showing an outline of an ion beam evaporation apparatus used to form the above-mentioned surface protective film (1). In the figure, (5) is a cluster ion beam generation source.1. ;(Qi 'L source (51), ion 1H f stage (5
2), ion beam acceleration TS [ri (53), etc.]. ]-note;, 'xt Q source (51) is the acid (sin) or vaporized material such as titanium (T1) stored in (51a) in Rut 7 (51a). (5l b ) etc. (1;
)! i gas ion beam is emitted by -L lfQ, and a reactive gas such as a gas containing oxygen and carbon elements such as -carbon oxide 7: (Co), carbon dioxide + (CO2), etc. is injected Q4.
Gas jet 1 nozzle (61), this jet 1] nozzle (
ionization means (62) for exciting, dissociating and ionizing the reactive gas injected from the ionization stage (61);
The gas ions generated by 2) are transferred to the disk substrate (10
) in the direction of the ion beam accelerating electrode (63) and the gas ion source (6) at a higher gas pressure than the surrounding space.

[It is equipped with a shield plate (64) etc. In addition, the ionization lower stage (62) in h is the electronic bee 1
, what are the extraction electrodes (62a) and the electron beam emitting filament (62b) used for? And 2 raster ion beam 4tE source (5)
, gas ion beam source (6) and disk substrate (
10) is held in a predetermined collapse state (not shown) [νed true'
It is stored in a tank. The case where an entrance surface protective film made of silicon oxide carbide λ (SiOc2 to X) is formed using the ion beam triple scanning device configured as described in 1-1 will be explained. 1. Inside the vacuum chamber by a vacuum evacuation system (not shown).
OX! After evacuating to a vacuum level of 0-3 Torr, inject gas into monoacid and arsenic as a reactive gas.
(Introduced from the nozzle (61), electron beam emitting filament) (62a) The electron beam extractor g! is arranged downstream of the gas injection nozzle (61). (grid)(
62b) to release electrons to [shear, dissociate and ionize -carbon (Co) gas] into a highly activated state. A bias voltage is applied between the ionization means (62) and the ion beam acceleration means (63) to extract and roughly accelerate the ions, which excite and dissociate them together with the t2-carbon oxide (Co) gas onto the disk substrate (IQ). ), silicon monoxide (S io ) (51b), which is a vapor deposition substance filled in the crucible (51a), is heated by a filament installed in the R air generation source (5I) to generate steam and Eject as a cluster. After the vapor and clusters are partially ionized by the ionization means (52), the ion beam acceleration means (53)
Accelerated by the disk substrate (10) together with non-ionized neutral vapor and clusters, this causes a chemical reaction with excited, dissociated and ionized carbon monoxide gas present near the disk substrate (10). Then, silicon oxide carbide (SIO) was deposited on the disk substrate (10).
A: A 1D protective film (11) consisting of a J thin film is formed. Next, the present invention will be explained in detail by giving examples. Example 1 N1-Cu- as a base layer on the surface of an Al-Mg alloy substrate
As a magnetic recording medium layer, r-
A Fe203 film was formed. A silicon oxide carbide film (S i 0,2C1lQ in this case) was provided as a protective film on this magnetic recording medium layer by the method described in I-.The thickness of the silicon oxide carbide film was set to 500. A fluorine-based lubricant (in this case, KR
YOTO￥:157Fs/M (trade name, manufactured by DuPont) was spin-coated at a concentration of 1 wt % and a rotational speed of 200 rpm to form a lubricating film, thereby forming a magnetic disk. Example 2 1t below on the surface of the AI-Mg alloy substrate! ! N+C as a layer
A Co-Ni-Cr film was formed as a magnetic recording medium layer on the base material on which the u-P plating film was formed. A silicon oxide carbide film (S i Ol, 2C11g in this case) was provided on this magnetic recording medium layer as a protective film by the method described above. The thickness of the silicon oxide carbide film was set to 500. On this film, aminosilane (silane coupling agent:
NH2CIhCH2NHCrH60Si(OCthh
) of 0.1 wt% solution 7α was applied by rotation at a rotational speed of 20 rpm, and then fluorine-based lubricant KRYTOX 157 was applied.
FS/M was applied under the same conditions as in Example 1 to form a lubricating film and form a magnetic disk. Comparative Example N1-Cu- as a base layer on the surface of an Al-Mg alloy substrate.
γ- as a magnetic recording medium layer on the base material on which the P plating film was formed
A Fe2O3 film was formed. A SiO2 film was formed as a protective film on this magnetic recording medium layer by Svanta. Sputter strip (for cows RF power 300W/8 Inno f5
Argon pressure: 3 mTorr-CS. S + 0
The film thickness for 2 was set to 500 people. This film - here) 7 Myo-based lubricant 'I) KRYOTOX157FS/M is used! i'
Coating was performed under the same conditions as Example 1 to form a lubricating film and a magnetic disk was formed. The period characteristics of magnetic disks including these comparative examples are not shown below. The surface roughness of the magnetic disk of Example 1 was measured using a stylus type surface roughness meter, and the results are shown in the characteristic diagram of FIG. Example 2
, and Comparative Example 1 showed similar characteristics, so their characteristic diagrams will be omitted. [In 4, the vertical axis represents the surface roughness of the disk, and the horizontal axis represents the hardness of the disk.Minor irregularities were observed on the surface of the disk. A 3370 cedar ferrite head was brought into contact with the surface of the magnetic disk, and the static cedar coefficient was measured.For the magnetic disk of Example 1, O, t
9- It was 0.20 for the magnetic disk of Example 2 and 0.20 for the magnetic disk of Comparative Example. All showed good characteristics. Here, a CSS test, which is an FF1J long-term test for magnetic disks, was conducted. A 3370 type head whose slider material was sapphire was used. Figure 4 is a characteristic diagram showing the results of the CS S test, where the vertical axis is the normalized playback output with the two swords 1j)l playback output as 1, and the horizontal axis is the C9S times f.
i (X 10"). In the figure, the line connecting the ○ marks shows the characteristic curve of the disk of Example 1.2 of the present invention, and the line crossing the X mark shows the characteristic curve of the disk of the comparative example. In the case of the disk of Embodiment 1.2 of this invention, the CS
Even at 20,000 times of CS, the reproduction output fl (lower) was not observed.On the other hand, in the comparative example, although no decrease in the 11f raw output was initially observed, the reproduction output gradually began to decrease from around 8,000 times of CS S. , after 20,000 times, the distance between the strings became 50%.The surface roughness of the magnetic disk after 500 times of css was measured with a one-needle surface roughness meter.'X5 figure is C5S5.
1 of the surface m of the magnetic disk of Example I after 000 cycles
61>1 is a characteristic diagram showing the measurement results of the surface roughness of the magnetic disk of Example 2, and FIG. 7 is the characteristic diagram showing the measurement results of the surface roughness of the magnetic disk of Comparative Example 2. FIG. In the figure, (11) represents the area where the magnetic head contacts the magnetic disk by contact start/stop. A comparison with the roughness of the periphery shows that the magnetic disk of Example 1.2 has an initial surface roughness of 1 level. On the other hand, it can be seen that in the magnetic disk of the comparative example, J portions corresponding to minute protrusions are removed. In addition, a head was brought into contact with the surface of the magnetic disk that had been subjected to CS 55,000 times, and the coefficient of static friction was measured by leaving it for 8 hours in a state of 185% Do'C.The coefficient of static friction was 0.22 for the magnetic disk of Example 1, 0.24 for magnetic disks
In the magnetic disk of Comparative Example 1, it exceeded 0.9, and an adsorption phenomenon was observed. Comparing the lubricant film thickness of Example 1.2 after the C S S surface determined by i!!II by 1" T - [R i), the residual lubricant:r7 ratio was 92% in Example 1. , Example 2
was 100%. It is thought that the presence of a silane coupling agent is more effective in retaining the lubricant. The presence of a silane coupling agent has the effect of improving the lubricant residual rate. However, even if there is no C
No adverse effects were observed on the 8S test. The magnetic recording medium according to the embodiment of the present invention obtained as described in ``-2'' contains accelerated ions and is formed using a t'' thin film formation method, so that the adhesion strength of the silicon oxide carbide surface protective film is higher than that of conventional sputtering. In addition, since it contains carbon yr and WK, it is not a scale that has high wear resistance, but the hardness is increased by changing the composition ratio of oxygen (X) and carbon (2-x). It also has the advantage that it can be changed freely, so it can provide a surface protective film that matches the hardness of the magnetic head, and has excellent head crush resistance.Furthermore, it can be easily formed using a low-temperature process. It can be manufactured cheaply and has stable quality. For example, in the case of cluster ion beam method, the composition ratio of lv2 (x) and carbon (2-x) can be adjusted by adjusting the gas pressure, flow rate, etc. The film thickness of silicon oxide carbide (SioAC2-=) is 1
Below 00 Å, the film is not uniform;
In this case, the distance between the magnetic head and the magnetic recording medium layer of the magnetic disk increases, resulting in an adverse effect of reducing the raw FiG output. Therefore, the thickness of the film with silicon oxide carbide is 1
Suitable for 00-1000 people. Ease of film formation, uniformity, II raw output output is preferably 300 to 800 people. In addition, if the surface roughness of the base material is Rmax 100 Å or less, absorption will definitely occur, and if it is more than 1,000 people, it is not preferable to prevent the protrusions from colliding with the floating magnetic head because it will affect the flying characteristics of the magnetic head. . In order to keep the static frictional force small and stable with good reproducibility, Rmax is preferably 400 to 800 people. In the above embodiments, a Claskku ion beam evaporator was used, but a vacuum evaporator, an ion blating device, a sputtering device, etc. may also be used. Instead of using a gas ion beam device, an L2 evaporation device may be used instead in a carbon monoxide (CO) atmosphere. In addition, silane (SiHa), carbon oxide 1 (C
o), by introducing oxygen gas etc., oxidized silicon carbide manure (S +
Ox C2-1) may be formed. In Example L, the magnetic recording medium layer is made of γ-Fe.○. Although the case described above has been described, a metal oxide medium such as CrO2 may also be used, and the old record has the same effect as the example s. Further, the magnetic recording medium layer is C. Although the case of Ni-Cr has been described, other C. - alloy medium with Ni, co-Cr, Fe,
A metal medium may also be used, and the same effects as in the embodiment L can be obtained. Furthermore, - in the above embodiment, the base layer is an N1-P plating film,
Although the case of the N1-Cu-P plating film has been described, other alumite films may also be used, and the same effects as in the above embodiments can be obtained. In general, a silicon oxide carbide film (S
A protective film of IOXC2-2) may be formed, and the same effect as in the above embodiment can be obtained. Furthermore, in the above embodiment, R is used as the fluorine-based lubricant.
Although the case where YTOX157FS/M is used has been described, for example, a flash lubricant such as Fomblin, De1, Namna, etc. may also be used, and the same effect as in the above embodiment can be obtained. In Example 2, the case where aminosilane was used as the silane coupling agent was explained, but other silane coupling agents having epoxy groups, hydroxyl groups, etc. may also be used. play. [Effects of the Invention] As described in 1 below, according to the present invention, by forming the protective film 17, which covers and protects the magnetic recording medium layer, from silicon oxide carbide, the abrasion force and adsorption between the magnetic recording medium and the magnetic head can be reduced. This has the effect of providing a highly reliable magnetic recording medium with low force and excellent durability.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing an F11 disk according to an embodiment of the present invention, FIG. 2 is a configuration diagram showing an example of a manufacturing apparatus according to the invention, and FIG. FIG. 4 is a characteristic diagram showing the results of surface thickness measurement according to the total ζ. FIG. , FIG. 7 is a characteristic diagram showing the results of surface roughness measurement using a surface roughness meter for a magnetic disk according to an embodiment of the present invention and a magnetic disk according to a comparative example after 555,000 cycles, and FIG. The cross section shown [? It is I. (1)...Al-Mg alloy substrate, (2)...Underlayer of the magnetic recording medium layer, the base material is composed of the Al-Mg alloy substrate (1) and the base layer (2). (3)...magnetic recording medium layer, (4)...1ri made of silicon oxide carbide
, ;f Maki. In addition, in the figures, the same reference numerals indicate the same or similar parts.

Claims (1)

[Claims] A base material, a magnetic recording medium layer formed on this base material, and a silicon oxide carbide (SiO_x
A magnetic recording medium comprising a protective film made of C_2_-_x) and a lubricating film covering the protective film.