JPH05166174A - Magnetic recording medium - Google Patents

Abstract

PURPOSE:To reform a protective film and to improve the corrosion resistance and the sliding durability by implanting ions of hydrogen atoms in the protective film. CONSTITUTION:A 10-20mum thickness NiP plated base film 2 on an Al substrate 1, a 50-300nm thickness Cr intermediate film 3 on base film and besides a 30-60nm thickness CoCr magnetic film 4 on the film 3 are formed. Further on the film 4 a 20-50nm thickness carbon protective film 5 is formed by sputtering and an ion implantation layer 10 having corrosion suppressing effect is formed in the film by H ion implantation and a lubricating film 6 is applied on the layer 10. At this time, since the implanted ions are not present in the magnetic film, the magnetic characteristics are not affected and the corrosion resistance and the sliding durability are enhanced.

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 in which a thin film of a ferromagnetic metal is formed on a non-magnetic substrate and a protective film and a lubricating film are provided on the thin film.

[0002]

2. Description of the Related Art A magnetic recording medium has a CoNi system containing Co as a main component from a conventional iron oxide, as the density of magnetic recording has increased.
Alternatively, a medium provided with a thin film of CoCr-based magnetic metal by sputtering or plating is being put to practical use. However, in order to maintain and secure the reliability of this recording medium, that is, the recording and reproducing characteristics for a long period of time, it is necessary to improve the sliding resistance with respect to the head and the corrosion resistance.
Therefore, methods of forming various protective films on the magnetic metal have been proposed. However, with any protective layer,
Since it must be composed of a thin film with a thickness of nm, it is not possible to eliminate microscopic pores and surface defects, and it is not possible to ensure the waterproofness to prevent water penetration. Those which improve the mechanical durability of the protective film are disclosed in JP-A-1-263912 and JP-A-60-23.
As described in 7634 or JP-A-2-12614,
There is a diamond protective film in which nitrogen is ion-implanted to increase strength and improve sliding resistance.

[0003]

Actual magnetic disks are usually required to be maintenance-free for 10 years or longer and free from data destruction. For that purpose, at the same time, it is required to reduce data destruction due to corrosion and reduce frictional wear due to head sliding. In this conventional technique, even if the sliding resistance is improved, the environment resistance, especially the corrosion resistance cannot be solved at the same time. It is an object of the present invention to provide a highly reliable recording medium that satisfies these two properties.

[0004]

The present invention is accomplished by injecting hydrogen ions into the protective film of the magnetic recording medium on the surface of the protective film to modify the protective film itself.

[0005]

[Function] When a small atomic weight atom such as hydrogen ion is injected into the protective film, the structure of the injected material becomes extremely dense,
The mechanical strength can be improved. Further, impurities existing in the tissue are removed by the reduction reaction, so that a film having high purity and environment resistance can be formed. As a result, it is possible to realize a recording medium with high reliability in both sliding resistance and corrosion resistance.

[0006]

EXAMPLE A first example of the present invention will be described below with reference to FIGS. 1 to 6 and Tables 1 and 2, and a second example will be described with reference to Table 3. FIG. 1 is a cross-sectional view showing a film structure of a magnetic recording medium of a first embodiment of the present invention, FIG. 2 is a view showing an elemental analysis result in the depth direction thereof, and FIG. 3 is a magnetic field of an embodiment of the present invention. FIG. 4 is a cross-sectional view showing a disk manufacturing apparatus for manufacturing a recording medium, FIG. 4 is a cross-sectional view of an apparatus showing an ion implantation part of the apparatus shown in FIG. 3, and FIG. 5 is a corrosion resistance test of the magnetic recording medium shown in FIG. 6 shows the results of the anodic polarization characteristics, and FIG. 6 shows the results of corrosion resistance obtained by measuring changes in the magnetic characteristics of the ion-implanted magnetic recording medium under high temperature and high humidity conditions. Further, Table 1 shows the result of the friction resistance performance with the head of the magnetic recording medium of the first embodiment, the result of the static friction performance with the head, and Table 2 shows the result of the dynamic friction performance. Table 3 shows the results of the wear resistance performance of the head of the magnetic recording medium of the second embodiment.

The film structure of the recording medium of the first embodiment is Al
10 to 20 μm thick NiP plating base film 2 on the substrate 1, and a thickness of 50 nm on the substrate 1 as shown in FIG.
.About.300 nm Cr intermediate film 3, with a thickness of 30 to 60 thereon
nm CoCr-based magnetic film 4 and a thickness of 20-
A carbon protective film 5 having a thickness of 50 nm is formed by sputtering, and an ion implantation layer 10 having a corrosion inhibiting effect formed by H ion implantation is formed in the carbon film, and a lubricant such as a perfluoropolyether agent is formed on the ion implantation layer 10. Is applied by the dip method to form the lubricating film 6.

The results of the depth component analysis of this recording medium are shown in FIG.
Will be explained. Depth analysis of the recording medium is usually
Elemental analysis is performed while dry etching the surface using Auger electron spectroscopy (AES) or secondary ion mass spectrometry (SIMS). In FIG. 2, the vertical axis represents the detected intensity of each element, and the horizontal axis represents the etching time from the surface, that is, the depth from the surface. The lubricant film is removed before analysis. A carbon protective film 5, a cobalt / chromium magnetic film 4, and a chromium intermediate film 3 are formed in this order from near the surface. When the elements forming each film are formed by a normal sputtering process, each component metal of the film structure has a similar shape, but shows a unique depth distribution after the surface layer treatment such as ion implantation. First, the carbon protective film 5 is composed of carbon A ₁ and an ion-implanted layer A ₂ . The magnetic film 4 shows cobalt B ₁ , chromium B _2, and a third additive element B ₃ . The chromium of the intermediate film 3 is represented by C ₁ . The ion-implanted layer A ₂ is characterized in that it does not match the maximum concentration depth (center depth of distribution) of the other elements constituting the protective film, and since it is almost absent in the magnetic film, There is almost no effect on the magnetic properties.

Next, an apparatus for manufacturing this magnetic recording medium will be described with reference to FIGS.

An Al substrate 31, which is formed by plating NiP, is fixed on a pallet 13 of the in-line linear transfer type in the manufacturing apparatus main body 19 and is hung in a rail 14 and travels in the direction of the arrow. The substrate 31 can be simultaneously formed and processed from both sides. A Cr sputter device 15 for forming the Cr intermediate film 3, a CoCr sputter device 16 for forming the CoCr-based magnetic film 4, and a carbon protection. The carbon device 17 for forming the film 5 is run in this order, and after the film is formed, it enters the pretreatment unit 18 and then the ion implantation device 32.
In this apparatus, a Cr / CoCr-based magnetic film and carbon are continuously formed by a sputtering method, and then H ions are implanted by a bucket type ion implanter 32 to form the ion implanted layer 10.

Details of the ion implanter 32 will be described with reference to FIG. In this ion implanter, a magnetic recording medium 12 (having a substrate 31 formed thereon) is fixed on a pallet 13 of an in-line linear transport type inside a vacuum chamber 20 to which a vacuum pump 21 is connected, and the entire surface of the medium is fixed. It is configured to allow ion implantation. Ion source 2
2 has a structure in which the gate valve 23 can be opened to implant ions.

After being supplied from the gas container 25 through the gas controller 24, the ion source 22 is ionized by the filament power supply 26, and the ions can be accelerated by the acceleration power supply 27. In this device, when different ions are continuously injected, the introduction port of the gas controller 24 is switched to allow ion injection. Further, since the ion source generates a large amount of heat, the pure water cooling device 2
8 is attached. When the gate valve 23 described above is opened, implanted ions can be irradiated from the ion source 22 to the magnetic recording medium 12 in the vacuum chamber 20. The implantation conditions of this ion implantation apparatus are an acceleration voltage of 15 kV, an ion current density of 0.31 mA / cm ² , a degree of vacuum of 1 × 10 to ⁵ torr, and an implantation time of 30 seconds. By selecting such implantation conditions, the temperature rise of the surface of the magnetic recording medium can be suppressed to 250 ° C. or less, and ion implantation is performed only in the magnetic film surface layer, so that the magnetic characteristics are not deteriorated.

Next, the results of measuring the corrosion rate of the recording medium of the first embodiment will be described. The measurement method was carried out according to the anodic polarization measurement method according to Japanese Industrial Standard JIS0579. It is generally known that even in the corrosion phenomenon under the atmospheric environment, the one caused by the humidity has a good correlation with the result of the corrosion current in the solution. The corrosion rate of a metal corresponds to the fact that the metal is ionized and a current flows, so the corrosion performance can be evaluated by its magnitude. Fig. 5 shows the results of measuring the anodic corrosion current density at each potential by increasing the potential from -0.2 V (calomel electrode potential) to +0.6 V in the deoxidized 1% sodium sulfate solution of the test solution. The vertical axis is the log scale. In the case of the non-ion-implanted sample, the corrosion potential is -0.17 V, and at 0 V it is about 1 μA / cm ² , 0.4 V.
While the corrosion potential of the sample in which N was injected and the inhibitor was formed in the protective film did not change much to -0.09V, it was 0.4 μA / cm ² at 0.4V at 0V.
.mu.A / cm ^2, and 0.4V in 1.5 .mu.A / cm ² Corrosion current density is small, is observed greatly reduced effectively the corrosion rate. Next, FIG. 6 shows the result of examination on deterioration of the magnetization characteristics in an atmospheric environment including humid air. The coercive force Hc (0e) of the magnetic film 4 was measured together with the result of time under the corrosion acceleration environment of 80 ° C. × 95%, and the result is shown in FIG. Of the two magnetic recording media having a coercive force Hc of 950 oersted (0e) in the initial stage, one of the magnetic recording media was implanted with H ions under the above conditions and compared with a non-implanted medium. Uninjected ones decreased from around 8 days, and decreased by about 10% on the 10th day. Also,
The amount of the ion-implanted medium decreased from about 16 days, and decreased by about 10% on the 17th day. As described above, it was confirmed that the ion implantation prolongs the life by about twice even in the corrosion acceleration test under high temperature and high humidity.

On the other hand, in an actual magnetic recording medium, it is essential to secure not only the corrosion resistance but also the sliding resistance with the magnetic head. Friction and wear when starting / stopping the recording medium and adsorption (adhesion) with the head when stopping
Is required to be small. Since a magnetic disk device normally repeats CSS (contact start / stop) operations, it is desired that the friction coefficient does not change even after many CSS operations. Therefore, the sliding resistance performance is evaluated from the change of the dynamic friction coefficient according to the number of times. The head is a winch-ester type magnetic head slider.
Table 1 shows the results of measuring the dynamic friction coefficient μ by setting gf.

[0015]

[Table 1]

Initially, the uninjected medium was 0.10, but when the number of CSSs exceeded 1,000, it rose sharply to 0.28 at 10,000 times and to 0.44 at 30,000 times. As opposed to
In the ion-implanted medium, μ is 0.20 even after 30,000 times.
As a result, stable slidability was exhibited without increasing to a practically problematic level. It is considered that this is because the stability of the medium surface was increased by the ion implantation, and at the same time, the strength and hardness were increased. In addition, in order to investigate the adsorption (adhesion) characteristics with the head under high humidity environment, 25
Table 2 shows the results of measurement of the static friction coefficient μs after leaving it for 1 week at 90 ° C. × 90% RH. Although the μs increased compared to the initial stage, the ion-implanted medium was superior because the increase range was smaller.

[0017]

[Table 2]

As described above, according to the first embodiment, by implanting ions from above the protective film of the magnetic recording medium, it is possible to improve the corrosion resistance and the sliding resistance without deteriorating the magnetic conversion characteristics. In particular, even if the carbon protective film is worn to some extent, the corrosion inhibiting layer is present in the protective film, so that stable corrosion resistance can be maintained.

Next, a second embodiment will be described. Differences from the first embodiment will be described below. The protective film forms boron nitride (BN), and then methane CH ₄ is added to accelerate voltage 2
Ions are implanted at a high voltage of 0 kV, and lubricating oil such as perfluoropolyether oil is applied on the surface thereof. By implanting C having a large mass number at the same time, the ion-implanted layer 17 of H atoms can be introduced not only near the surface but also deeply in the depth direction. Therefore, the wear resistance and the adhesion of the composite film are significantly improved. Table 3 shows the results of measuring the amount of friction of the medium protective film due to the head sliding of this magnetic recording medium.

[0020]

[Table 3]

After passing 30,000 times of CSS, the unimplanted medium is 8.2 nm, while the ion-implanted medium is 1.
It was found that the wear resistance was significantly improved to 2 nm. This is effective in significantly increasing the corrosion resistance because the hydrogen atoms ion-implanted deep into the protective film reduce and remove impurities in the film. As described above, according to the second embodiment, not only the effect of significantly improving the wear resistance but also the effect of increasing the corrosion resistance are provided.

Although the medium constituent elements and the ion implantation elements are specified in the above embodiments, the purpose of the present patent is to accelerate hydrogen ions under a high voltage and implant them in the protective film of the magnetic recording medium to form a protective film. It is modified to improve the environment resistance.

The magnetic recording media of the first and second embodiments are
Usually its outer diameter is 2.5 ", 3.5", 5.25 ", 8 to 1
4 ″, one or a plurality of sheets are fixed to the spindle rotating portion of the magnetic recording medium installation portion, and the magnetic conversion head is provided so as to face the spindle rotating portion, thus constituting the magnetic recording device. In order to ensure the reliability of various magnetic recording data, it is essential to improve the weather resistance and sliding resistance of the magnetic recording medium, and a magnetic recording device can be realized.

[0024]

According to the present invention, the hardness and strength of the protective film can be increased, the sliding resistance with the head can be improved, and the corrosion resistance can be improved at the same time.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of a recording medium showing a first embodiment of the present invention.

2 is an explanatory diagram showing the results of elemental analysis in the depth direction of the medium shown in FIG.

FIG. 3 is a cross-sectional view of a recording medium manufacturing apparatus of the present invention.

4 is a sectional view showing an ion implantation part of the manufacturing apparatus of FIG.

FIG. 5 is an explanatory diagram showing measurement results of an anodic polarization curve showing corrosion resistance performance in a solution of the magnetic recording medium of the first embodiment of the present invention.

FIG. 6 is an explanatory diagram showing the results of time-dependent changes in coercive force showing corrosion resistance under high temperature and high humidity in this example.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Substrate, 2 ... Base film, 3 ... Intermediate film, 5 ... Protective film, 6 ... Lubrication film, 7 ... Ion-implanted layer, 12 ... Magnetic recording medium.

Claims (1)

[Claims] 1. A recording medium having a magnetic thin film formed on a non-magnetic substrate and a non-magnetic protective film on the magnetic thin film is subjected to ion implantation treatment with an element containing hydrogen ions, and lubrication is further performed thereon. A magnetic recording medium, characterized in that an agent is applied.