JPH04102225A - Magnetic recording medium and production thereof - Google Patents

Abstract

PURPOSE:To improve both of corrosion resistance and sliding resistance by forming a coupling layer on a protective film surface, implanting ions into the protective layer and then coating and surface with a lubricating film. CONSTITUTION:On an Al substrate 1, there are formed a NiP plating base film 2 of 10 - 20 mum thickness, Cr intermediate film 3 of 50 - 300nm thickness, and CoCr-base magnetic film 4 of 30 - 60nm thickness, and carbon protective film 5 of 20 - 50nm thickness, each by sputtering. An ion-implanted layer 10 having the effect of suppressing corrosion is formed in the carbon film by implating N ions, and a lubricant coupling layer 11 is formed on the surface of the carbon film. Further, a lubricant such as perfluoropolyether etc., is applied by dipping to form a lubricating film 6.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention involves forming a thin film of ferromagnetic metal on a non-magnetic substrate,
The present invention relates to a method for manufacturing a magnetic recording medium and a recording medium having a protective film and a lubricating film provided thereon.

[Conventional technology]

With the increasing density of magnetic recording, magnetic recording media are changing from conventional iron oxide to CoNi based mainly on CO or CoC.
Practical use of media in which r-based magnetic metals are formed into thin films by sputtering or plating is progressing. but,
In order to ensure the reliability of this recording medium, that is, to maintain long-term recording and reproducing characteristics, it is necessary to improve the sliding resistance with the head and the corrosion resistance.

Therefore, methods of forming various protective films on the magnetic metal have been proposed. However, for any protective layer, several tens of
Since it must be composed of a nano-thin film, it is impossible to eliminate minute porosity and surface defects, and waterproofness sufficient to prevent moisture penetration cannot be ensured.

To improve the mechanical durability of the protective film, JP-A-0
Publication No. 1-263912 or JP-A-02-1261
As described in Japanese Patent No. 4, there is a method in which nitrogen ions are implanted into a diamond protective film to increase strength and improve sliding resistance. On the other hand, as a method for firmly adhering a lubricant to a carbon protective film, there is a method that improves water resistance by performing surface coupling treatment by irradiating ultraviolet rays in an ozone atmosphere, as described in JP-A-2-27522. be.

[Problem to be solved by the invention]

However, actual magnetic disks are normally required to be maintenance-free and free of data destruction for 10 years or more. To this end, it is required to simultaneously destroy data due to corrosion and reduce frictional wear due to head sliding. Although the above-mentioned conventional technology improves sliding resistance, there is a problem in that environmental resistance, especially corrosion resistance reliability, cannot be solved at the same time.

The purpose of the present invention was to solve the above-mentioned problems, and to provide a highly reliable recording medium manufacturing method and recording medium that simultaneously satisfy the two properties of corrosion resistance and sliding resistance. That's true.

[Means to solve the problem]

In the present invention, after forming a coupling layer (adhesion layer) that has a lubricant adhesion effect on the surface of the protective film, ions such as nitrogen ions are injected into the protective film of the magnetic recording medium, thereby making the protective film itself structurally resistant. The above objective is achieved by forming a film with high properties and then applying a lubricating film.

[Effect]

According to the above structure, when ions are injected into the protective film and then a reaction is caused therein to form a corrosion-inhibiting layer, the surface is stabilized and reactions such as coupling are greatly suppressed.

As a result, the lubricant does not adhere well. In addition, since the coupling reaction of the lubricant mentioned above can cause adhesion particularly on corroded oxide layers, a coupling layer with high affinity for the lubricant can be formed by treatment such as ultraviolet light or leaving it in a highly humid environment. After that, ion implantation is performed to form a corrosion inhibiting layer (inhibitor layer) with anti-corrosion effect in the protective film.The outermost surface is tightly coated with lubricant, and a corrosion inhibiting layer is formed in the protective film. I will do it.

As a result, even if the outermost surface of the protective film is slightly worn due to sliding, the corrosion-inhibiting layer in the film is maintained, thereby realizing a recording medium with high reliability in both sliding resistance and corrosion resistance.

〔Example〕

Hereinafter, the first embodiment of the present invention will be explained using FIGS. 1 to 6 and Table 19, and the second embodiment will be explained using Table 3.

FIG. 1 is a cross-sectional view showing the film structure of a magnetic recording medium according to the first embodiment of the present invention, FIG. 2 is a diagram showing the elemental analysis results in the depth direction, and FIG. 3 is an example of the present invention. 4 is a sectional view showing the ion implantation section of the device shown in FIG. 3, and FIG. 5 is a sectional view of the device shown in FIG. 1. FIG. 6 shows the results of the anode polarization characteristics obtained by testing the corrosion resistance of magnetic recording media. FIG. 6 shows the corrosion resistance results obtained by measuring changes in the magnetic properties of ion-implanted magnetic recording media under high temperature and high humidity.

Furthermore, Table 1 shows the results of the friction resistance performance with the head and the static friction performance results with the head of the magnetic recording medium of the first example.
Table 2 shows the results of the dynamic friction performance. Table 3 is the second
3 shows the results of the wear resistance performance of the head of the magnetic recording medium of Example 2.

The film structure of the recording medium of the first embodiment is that a NiP plating base film 2 with a thickness of 10 to 20 μm is formed on an AQ substrate 1.
, as shown in FIG.
m Cr intermediate film 3, on top of which a CoCr-based magnetic film 4 with a thickness of 30-60 nm, and further on top of that a 20-50 nm thick Cr intermediate film 3.
A carbon protective film 5 of m is formed by sputtering, and an ion implantation layer 10 having a corrosion inhibiting effect formed by N ion implantation is formed in the carbon film, and a lubricant coupling layer 11 is formed on the surface of the carbon film. A lubricant film 6 is formed by applying a lubricant such as a perfluoroboriether agent thereon by a dip method.

The results of depth component analysis of this recording medium will be explained using FIG. 2.

Depth analysis of recording media is usually performed using Auger electron spectroscopy (AES) or secondary ion mass spectrometry (SIMS).
Perform elemental analysis while tri-etching the surface.

In FIG. 2, the vertical axis represents the detection intensity of each element, and the horizontal axis represents the etching time from the surface, that is, the depth from the surface. The lubricating film was removed for analysis. A carbon protective film 5, a cobalt and chromium magnetic film 4, and a chromium intermediate film 3 are constructed in this order from near the surface.

When the elements constituting each film are formed by a normal sputtering process, each component metal of the film structure has a similar shape, but when a surface treatment such as ion implantation is performed afterwards, a unique depth distribution is exhibited. First, the inside of the carbon protective film 5 is composed of carbon A1, a layer A2 formed by a coupling process, and an ion-implanted layer A3. The magnetic film 4 shows cobalt B1, chromium B2, and a third additive element B3. Further, chromium in the intermediate film 3 is denoted by C1. The ion-implanted layer A3 is characterized in that it does not match the maximum concentration depth (central depth of distribution) of the other elements constituting the protective film, and is hardly present in the magnetic film. There is almost no effect on the characteristics.

Next, the manufacturing apparatus for this magnetic recording medium will be explained with reference to FIGS. 3 and 4.

An AQ substrate 31 plated with NiP is fixed on an in-line linear conveyance type pallet 13 in a manufacturing apparatus main body 19, and travels in the direction of the arrow while suspended from a rail 14. The substrate 31 is designed to allow film formation and processing from both sides at the same time.
Cr sputtering equipment W15, C for forming the r intermediate film 3
o The CoCr sputtering device i16 for forming the Cr-based magnetic film 4 and the carbon sputtering device 17 for forming the carbon protective film 5 run in this order, and after film formation, enters the coupling processing section 18, Thereafter, the ion implanter 32 is entered.

In these devices, Cr is removed by sputtering.

A CoCr-based magnetic film is successively formed with carbon, and then in the coupling processing section 18, the magnetic recording medium is irradiated with ultraviolet rays for about 2 minutes using a 500 W mercury lamp in an ozone atmosphere to form a coupling film that exhibits adhesion to the lubricating film. This is referred to as a processing layer 11. Thereafter, N ions are implanted using the ion implantation device 32 to form the ion implantation layer 10.

Details of the ion implanter I32 will be explained using FIG. 4. In this ion implantation device 132, a magnetic recording medium 12 (on which a substrate 31 is deposited) is fixed to an in-line linear conveyance type pallet 13 in a vacuum chamber 20 to which a vacuum pump 21 is connected, and the entire surface of the medium is The structure is designed to allow ion implantation. Ion source 22
The structure is such that ions can be implanted by opening the gate valve 23.

Inside this ion source 22, after being supplied from a gas container 25 through a gas controller 24, ions are ionized by a filament power supply 26, and the ions can be accelerated by an acceleration power supply 27. This device has a structure in which when different ions are to be implanted successively, the inlet of the gas controller 24 can be switched to perform the ion implantation.

Further, since the ion source generates a large amount of heat, a pure water cooling device 28 is attached. When the aforementioned gate valve 23 is opened, implanted ions are transferred from the ion source 22 to the vacuum chamber 20.
It is possible to irradiate the magnetic recording medium 12 inside. The conditions for implantation using this ion implanter are an acceleration voltage of 15 kV, an ion current density of 0.31 mA/d, a vacuum degree of 1X10-storr, and an implantation time of 120 seconds. By selecting such implantation conditions, the temperature rise on the surface of the magnetic recording medium can be suppressed to 250° C. or less, and ions are implanted only into the surface layer of the magnetic film, so that the magnetic properties are not deteriorated.

Next, the results of measuring the corrosion rate of the recording medium of this first example will be explained. The measurement method was carried out in accordance with the anodic polarization measurement method according to Japanese Industrial Standards JIS 0579.

It is generally known that among corrosion phenomena in the atmospheric environment, those caused by humidity have a good correlation with the corrosion current results in solutions. The corrosion rate of a metal corresponds to the ionization of the metal and the flow of electric current, so the corrosion performance can be evaluated based on its magnitude.

Figure 5 shows the potential of the test solution in a deoxidized 1% sodium sulfate solution raised from -0.2 V (calomel electrode potential) to +0.6 V, and the anode corrosion current density measured at each potential. The results are shown on a log scale on the vertical axis.

In the case of a sample without ion implantation, the corrosion potential is 10.17V, approximately 1μA/a& at Ov, and 40μA/a& at 0.4V.
In contrast, in the sample in which N was injected and an inhibitor was formed in the protective film, the corrosion potential did not change much at -0.09 V, but at OV it was 0.4 μA/cd, 0.
．． At 4V, the corrosion current density is as low as 1.5 μA/d, and the effect of greatly reducing the corrosion rate is recognized.

Next, FIG. 6 shows the results of investigating the deterioration of magnetization characteristics in an atmospheric environment containing humidity. FIG. 6 shows the results of measuring the coercive force Hc (Os) of magnetic WA4 in an 80'CX95% corrosion acceleration environment together with the time results.

Of two magnetic recording media with an initial coercive force He of 950 oersted (Oe), one was implanted with N ions under the above conditions and compared with a non-implanted medium. Those not injected decreased from around the 8th day, and decreased by about 10% on the 10th day. In addition, the ion-implanted medium decreased from around the 16th day, and the ion-implanted medium decreased from around the 16th day.
It decreased by about 10% day by day. In this way, it was confirmed that ion implantation has the effect of extending the life by about twice in accelerated corrosion tests under high temperature and high humidity conditions.

On the other hand, actual magnetic recording media have this corrosion resistance reliability and at the same time
It is essential to ensure sliding reliability with the magnetic head.6 It is required that friction and wear during starting/stopping of the recording medium and adhesion (adhesion) with the head during stopping are small. Since magnetic disk drives usually repeat CSS (Contact Start Stop) operations, it is desirable that the friction coefficient does not change even after many C8S operations.

Therefore, the sliding resistance performance is evaluated based on the change in the coefficient of dynamic friction depending on the number of times. The head was a winchiesta type magnetic head slider, and the pressing load was set at 10 gf, and the dynamic friction coefficient μ was measured. Table 1 shows the results.

Table 1 The uninjected medium initially had a value of 0.10, but the C8S
When the number of times exceeds 1,000 times, it suddenly increases, and it increases to 0.28 at 10,000 times.
was 0.20, indicating stable sliding properties without increasing to a level that would pose a practical problem. This is thought to be due to the fact that the stability of the medium surface was increased by ion implantation, and at the same time, the strength and hardness were increased.

Furthermore, in order to investigate the adsorption (adhesion) characteristics with the head in a high humidity environment, the static friction coefficient μS was measured after being left at 25° C. and 90% RH for one week. Table 2 shows the results. Initially, μS increased somewhat with the ion-implanted medium compared to the non-implanted medium, but the ion-implanted medium had a smaller increase and was superior.

Table 2 As described above, according to the first embodiment, by implanting ions from above the protective film of the magnetic recording medium, the corrosion resistance and the sliding resistance can be improved without deteriorating the magnetic conversion characteristics. In particular, even if the carbon protective film is slightly worn, the corrosion-inhibiting layer is present in the protective film, so that stable corrosion resistance reliability can be maintained.

Next, a second example will be described. Differences from the first embodiment will be described below. The protective film is formed of zirconium oxide and then left in a normal atmospheric environment for about two days or more. After that, N was ion-implanted at an acceleration voltage of 30 and a high voltage of ■.
Subsequently, H ions are implanted, and a lubricating oil such as perfluoroboriether oil is applied onto the surface.

By implanting H in this way, an amine-based nitrogen compound layer is formed not only near the surface of the ion-implanted layer 10 but also considerably deep, and a part of the layer is even a magnetic film. Therefore, the wear resistance and adhesion of the composite membrane are significantly improved.

Table 3 shows the results of measuring the amount of friction on the medium protective film caused by head sliding of this magnetic recording medium.

Table 3 After 30,000 cycles of C8S, the amount of uninjected medium was 8.
．． 2nm, whereas the ion implantation medium is 1.2nm.
It was found that the wear resistance was significantly improved. This is because the nitrogen compound layer is formed deep into the protective film by ion implantation, which has the effect of significantly increasing corrosion resistance. Most of these nitrided compounds are amine-based substances, but depending on slight differences in other conditions, linear amine compounds, cyclic amine compounds, ammonium salts, etc. can be produced.

As described above, according to the second embodiment, there is an effect of significantly improving the wear resistance, and at the same time, there is an effect of increasing the corrosion resistance.

In the above embodiments, the elements constituting the medium and the ion-implanted elements are specified, but the gist of the present invention is to accelerate nitrogen ions under high voltage and implant them into the surface of the magnetic recording medium film to form the compound within the material. and to fix it. This compound results in improved environmental resistance.

The magnetic recording media of the first and second embodiments usually have an outer diameter of 2.5.3.5.5.25.8 to 14 inches, and one or more of them are magnetic recording media. A magnetic transducer head is fixed to the spindle rotation section of the medium installation section and is provided to face the spindle rotation section, thereby configuring a magnetic recording device.

Therefore, in order to ensure the reliability of such magnetically recorded data, it is essential to improve the weather resistance and sliding resistance of the magnetic recording medium, and the present invention provides a highly reliable magnetic recording device. It can be realized.

〔Effect of the invention〕

According to the present invention, it is possible to realize and manufacture a highly reliable magnetic recording medium that has high corrosion resistance and has improved sliding resistance by strongly fixing the lubricant to the surface of the medium. Furthermore, it has the effect of increasing the hardness and strength of the protective film and improving its adhesion.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view of a recording medium showing the first embodiment of the present invention, FIG. 2 is a diagram showing the elemental analysis results in the depth direction of the medium shown in FIG. 1, and FIG. 3 is a recording medium of the present invention. 4 is a sectional view showing ion implantation in the manufacturing device of FIG. 3; FIG. 5 is anode polarization showing the corrosion resistance performance of the magnetic recording medium of the first embodiment in a solution. A diagram showing the measurement results of the curve,
FIG. 6 is a diagram showing the results of changes in coercive force over time indicating the corrosion resistance performance under high temperature and high humidity conditions of this example. 1.31... Substrate, 2... Base film, 3.
... Intermediate film, 4... Magnetic film, 5... Protective film, 6...
・Lubricating film. 10... Ion implantation layer, 11... Coupling layer,
12...Magnetic recording medium, 13...Pallet, 15.
...Or sputtering device, 16...CoCr sputtering device, 17...carbon sputtering device, 18...coupling processing section, 20...vacuum chamber, 21...
- Vacuum pump, 22... ion source, 32... ion implantation device.

Claims (1)

[Claims] 1. A method for manufacturing a magnetic recording medium having a magnetic thin film formed on a non-magnetic substrate and a non-magnetic protective film on the magnetic thin film, comprising: first applying a lubricant to the surface of the protective film; 1. A method of manufacturing a magnetic recording medium, comprising: forming a coupling layer having a bonding force with a magnetic recording medium; thereafter performing ion implantation treatment on the protective film; and then applying a lubricant to the surface of the protective film. 2. In a method for manufacturing a magnetic recording medium having a magnetic thin film formed on a non-magnetic substrate and a non-magnetic protective film on the magnetic thin film, the surface of the protective film is first irradiated with ultraviolet light in an ozone atmosphere. A magnetic recording medium characterized in that a coupling layer having a bonding force with a lubricant is formed by performing ion implantation treatment on the protective film, and then a lubricant is further applied on the surface of the protective film. manufacturing method. 3. In a method for manufacturing a magnetic recording medium having a magnetic thin film formed on a non-magnetic substrate and a non-magnetic protective film on the magnetic thin film, the surface of the protective film is first held for a certain period of time in a high humidity environment. A magnetic recording medium characterized in that a coupling layer having a bonding force with a lubricant is formed by performing ion implantation treatment on the protective film, and then a lubricant is further applied on the surface of the protective film. manufacturing method. 4. A magnetic recording medium manufactured by the method according to claim 1, 2 or 3. 5. In a magnetic recording medium having a magnetic thin film formed on a non-magnetic substrate and a non-magnetic protective film on the magnetic thin film, the protective film has a bonding force with a lubricant at a depth of 10 nm or less from the surface. A magnetic field characterized in that a coupling layer is formed and the maximum concentration distribution in the ion-implanted layer introduced into the protective film exists in a deep layer from 5 nm to several tens of nm from the outermost surface of the protective film. recoding media. 6. On a non-magnetic substrate with a base film of NiP, Cr, etc. formed on a substrate mainly composed of aluminum or glass,
A cobalt-based magnetic film typified by oNi and CoCr, or an iron-based magnetic film typified by iron nitride such as Fe_2O_3 and FeN is formed, and a film with a thickness of 10 to 5 mm is formed on top of the cobalt-based magnetic film typified by oNi and CoCr.
A protective film made of carbon, SiO_2, or ZrO_2 with a thickness of 0 nm is formed, and N, Ar, H,
A magnetic recording medium having an ion-implanted layer made of either P or O, and having a surface of the protective film coated with a fluorine-based lubricant polyfluoropolyether.