JP2000353316A - Apparatus for production of magnetic recording medium - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make it possible to suppress the number of abnormal electric discharges even if a protective film deposition rate is increased by installing plural sputtering targets for forming the protective films in a vacuum chamber and connecting the respective sputtering targets to respective independent power sources. SOLUTION: The plural sputtering targets 14 and plural plasma generating electrodes 15 are installed. The respective sputtering targets 14 and the respective plasma generating electrodes 15 are connected to the respective independent DC power sources 16 and the AC power sources 18. The plasmas generated by respectively independently controlling the respective sputtering targets 14 and the respective plasma generating electrodes 15 are controlled, by which the abnormal electric discharges may be decreased even if the protective film deposition rate is increased and a film 6 is not broken. The sputtering targets or the plasma generating power source are divided and controlled by the respective independent power source, by which the entire making current is dispersed to the respective power sources to make the maximum current of the respective power sources smaller than the current at the time of the independent power source. The abnormal electric discharges are thereby decreased.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an apparatus for manufacturing a magnetic recording medium. In particular, the present invention is to produce a magnetic recording medium in which the number of abnormal discharges can be kept low even when the deposition rate of the protective film is increased, and the thickness of the protective film is abnormal, the characteristic of the protective film is abnormal, and the substrate film is less damaged. It is an object of the present invention to provide a manufacturing apparatus capable of performing the above.

[0002]

2. Description of the Related Art The recording density of a magnetic tape has been rapidly increased in recent years. In this process, the magnetic tape is made of iron oxide tape, metal tape, which has high coercive force and high magnetic flux density.
And to high performance thin film tapes. As an application of this magnetic tape, in the field of VTRs, in order to achieve digitization and high definition, a thin film tape is particularly attracting attention.

As this thin film tape, a so-called evaporation tape in which a magnetic film is formed by an oblique evaporation method has been put to practical use. Specifically, a magnetic material such as Co or CoNi in a crucible is irradiated with an electron beam using a pierce-type electron gun in a vacuum to melt and evaporate these materials.
While introducing oxygen, PET (polyethylene terephthalate), PEN (polyethylene naphthalate), PI
A thin film made of CoO or CoNiO is formed on a base film (nonmagnetic substrate) such as (polyimide) or PA (aramid).

Next, a protective film is formed on the magnetic film in order to improve the durability and corrosion resistance of the magnetic tape. DLC (diamond-like carbon) is often used as a protective film. This is effective in abrasion resistance when sliding with the head at the time of recording and reproduction because of high hardness and low coefficient of friction. In addition, the DLC film can be formed densely and uniformly on the surface of the magnetic film even if the DLC film is as thin as about 100 angstroms, so that a spacing loss which causes a decrease in output of the magnetic recording medium can be reduced. Further, since the magnetic film alone is easily oxidized, the oxidation can be prevented by the DLC protective film, and the corrosion resistance can be improved. Abrasion resistance and corrosion resistance are further improved by interaction with a fluorine-based lubricant formed on the protective film.

The DLC film is generally formed by a sputtering method, a CVD method, or the like. Figure 2 shows a general protective film deposition system.
Shown in An unwinding roll 2, a take-up roll 3, guide rolls 4, 5 and a cooling can roll 7 are arranged in a vacuum chamber 1, and a film 6 on which a magnetic film is formed is wound between these rolls. It travels from the unwinding roll 2 to the winding roll 3 in the direction of the arrow in the figure. A cooling device is disposed inside the cooling can roll 7 to prevent a thermal deformation of the film 6 due to a rise in temperature when a protective film is formed on the magnetic film of the film 6.

In the sputtering method, the carbon target 8 is connected to a power supply 9 for sputtering. The power source 9 for sputtering is DC, AC, RF, or a superposition thereof.
When an AC or RF power supply is used, a matching unit 9 ′ is provided between the power supply 9 and the target 8. Numeral 10 denotes a gas inlet, which forms a plasma by introducing Ar gas and forms a DLC film by sputtering a carbon target 8. At this time, a method of improving the film quality by introducing an additional gas such as N ₂ or H ₂ has been devised.

In the CVD method, the plasma generating electrode 13 is connected to the plasma power source 11 as shown in FIG.
The plasma power source 13 is DC, AC, RF, or a superposition thereof. When an AC or RF power supply is used, the matching device 12 is provided between the power supply 13 and the electrode 11.

[0008] From the gas inlet 10, C such as methane, acetylene, ethylene, benzene, toluene, xylene, etc.
A H-based gas is introduced, DC, AC, and RF voltages are applied to the electrodes to form plasma, the introduced gas is once decomposed by the energy of the plasma, and the DLC film is formed by recombining the carbon on the substrate. I do. At this time, N ₂ , H ₂
A method of improving the film quality by introducing an additive gas such as the above has also been devised.

[0009]

However, when the input power is increased by the above-mentioned sputtering method and CVD method in order to increase the deposition rate of the protective film, protrusions or minute film omissions on the magnetic film (pin-off). -), Abnormal discharge occurred in this portion, and a DLC film having a predetermined thickness and characteristics could not be formed uniformly. Further, when abnormal discharge is severe, the substrate may be broken. For this reason, it was difficult to improve the production speed in the conventional manufacturing apparatus. According to the present invention, it is possible to manufacture a magnetic recording medium in which the number of abnormal discharges can be suppressed even if the film forming speed of the protective film is increased, and the film thickness of the protective film is abnormal, the characteristic of the protective film is abnormal, and the substrate film is less damaged. It is intended to provide a device.

[0010]

Therefore, in order to solve the above-mentioned problems, the present invention provides a method in which a non-magnetic substrate on which a ferromagnetic metal thin film is laminated is moved in a predetermined direction along a can roll, and the non-magnetic substrate is sputtered. In a magnetic recording medium manufacturing apparatus for forming a protective film on a ferromagnetic metal thin film, a plurality of sputter targets for forming a protective film are installed in a vacuum chamber, and each of the sputter targets is connected to an independent power supply. A magnetic recording medium manufacturing apparatus, characterized in that a non-magnetic substrate on which a ferromagnetic metal thin film is laminated is moved in a certain direction along a can roll, and the ferromagnetic metal thin film is formed on the ferromagnetic metal thin film by a plasma CVD method. In a magnetic recording medium manufacturing apparatus for forming a protective film, a plurality of plasma generating electrodes for forming a protective film are installed in a vacuum chamber, and each of the plasma generating electrodes is formed. Apparatus for manufacturing a magnetic recording medium characterized by connecting the electrodes to the independent power supply,
Is provided.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS As a result of various studies to solve the above problems, as shown in FIGS. 1a and 1b, a plurality of sputter targets 14 and a plurality of plasma generating electrodes 15 are formed.
Is installed, and each sputter target 14 and each plasma generating electrode 15 are connected to independent power supplies 16 and 18. Then, each sputter target 14 and each plasma generating electrode 15 are independently controlled to control the generated plasma. As a result, it has been found that even if the total input power is increased in order to increase the protective film deposition rate, abnormal discharge can be reduced and the film 6 (substrate) can be prevented from being broken.

Since the discharge voltage depends on the gas pressure, it is constant once the film forming conditions are determined. Further, since the deposition rate is proportional to the input power, it is necessary to increase the discharge current in order to increase the deposition rate. The abnormal discharge current is larger than the current when a normal plasma is generated. In particular, this large current is locally applied to the discharge portion, which causes abnormal film thickness, abnormal DLC characteristics, and substrate destruction due to an increase in substrate temperature.

Although the abnormal discharge can be suppressed by limiting the maximum discharge current value on the power supply side, the film forming speed is limited and productivity cannot be improved. By dividing the sputter target or the electrode for plasma generation as described above and controlling the plasma with independent power supplies,
All input currents are distributed to each power supply, and the maximum current of each power supply is
By making the current smaller than that of the single power supply, the abnormal discharge can be reduced even if the total input current is increased, and the adverse effect at the time of the abnormal discharge can be eliminated.

The present invention will be specifically described with reference to the following examples. <Embodiment 1> As shown in FIG. 1-a, using a cooling can roll 7 having a diameter of 1000 mm, carbon targets 14 (sputter targets) having a size of 200 mm × 500 mm were installed at five places, and five DC power supplies 16 were connected. Each was connected to a different carbon target 14. A film 6 in which a 0.2 μm CoO thin film was previously formed on a 6.4 μm PET film by introducing Ar gas at a gas pressure of 2 mmTorr.
The (substrate) was run, and sputtering for forming a DLC film was continuously performed for one hour. The DLC film thickness was adjusted at a film speed, and a DLC film thickness of 100 Å was formed on the CoO magnetic film. Each power supply is controlled so that the set current becomes the maximum current. When the input voltage was changed at a discharge voltage of 1000 V, the total power, the discharge current of each power supply and the number of abnormal discharges, the number of abnormal film thicknesses found after the DLC film was formed,
Table 1 shows the number of substrate breaks. Below 100 is abnormal film thickness
With a film thickness other than ± 20 Å, substrate destruction means a perforation phenomenon of the substrate that can be found by visual observation.

Table 1 <Example 1> Total power Discharge current of each power supply Abnormal discharge number Number of abnormal film thickness Number of substrate destruction points 25kW 5A 0 0 0 35 7 0 0 0 50 10 0 0 0 75 15 1 1 0 100 20 2 1 1

Comparative Example 1 A DLC film was formed in the same manner as in Example 1 except that each carbon target 14 was connected to one common power supply in the apparatus shown in FIG. 1-a. When the input voltage was changed at a discharge voltage of 1000 V,
Table 2 shows the total power, the discharge current of a single power supply and the number of abnormal discharges, the number of abnormal film thicknesses and the number of substrate breaks examined after film formation.

Table 2 <Comparative Example 1> Total power Discharge current of single power supply Abnormal discharge number Number of abnormal film thickness Number of substrate destruction points 25kW 25A 0 0 0 35 35 4 2 2 50 50 10 3 7 75 75 25 10 15 100 100 42 15 27

<Embodiment 2> As shown in FIG.
Using the cooling can roll 7 of the above, the plasma generating electrodes 15 of 200 mm × 500 mm
Each of the two AC power supplies 18 was connected to a different electrode 15. A matching device 17 was provided between the electrode 15 and the power supply 18 so that matching was performed so that reflection from the electrode 15 was reduced. Acetylene gas is introduced and the gas pressure is set to 5 mmTorr.
CVD for forming an LC film was continuously performed for 1 hour. 6.4
A 0.2 μm CoO thin film was previously formed on a μm PET film, and the film speed was adjusted.
Angstrom was formed. Each power supply is controlled so that the set current becomes the maximum current. Discharge voltage 500V
Then, when the input power was changed, the total power, the discharge current of each power supply and the number of abnormal discharges, the number of abnormal film thicknesses found after film formation,
Table 3 shows the number of substrate breaks.

Table 3 <Example 2> Total power Discharge current of each power supply Abnormal discharge number Number of abnormal film thickness Number of substrate breakage points 12.5kW 5A 0 0 0 17.5 7 0 0 0 25 10 1 1 0 37.5 15 3 2 1 50 20 6 4 2

Comparative Example 2 A DLC film was formed in the same manner as in Example 2 except that the five plasma generating electrodes 15 were connected to one common power supply in the apparatus shown in FIG. 1-b. did. Table 4 shows the total power, the discharge current of the single power supply and the number of abnormal discharges, the number of abnormal film thickness locations examined after film formation, and the number of substrate breakdown locations when the input power was changed at a discharge voltage of 500 V.

Table 4 <Comparative Example 2> Total power Discharge current of single power supply Abnormal discharge number Number of abnormal film thickness Number of substrate destruction points 12.5kW 25A 0 0 0 17.5 35 2 1 1 25 50 10 2 8 37.5 75 22 8 14 50 100 38 12 26

From the results shown in Tables 1 to 4, the sputter target or the electrode for plasma generation is divided, and the plasma is controlled by independent power supplies, so that the total input current is distributed to each power supply and the maximum current of each power supply is controlled. Can be made smaller than the current when a single power supply is used, so that abnormal discharge can be reduced even when the total input current is increased, and the adverse effects of abnormal film thickness and substrate destruction can be reduced.

[0023]

As described above, according to the manufacturing apparatus of the present invention, the number of abnormal discharges can be suppressed even if the discharge current is increased and the deposition rate of the protective film is increased. It is possible to produce a magnetic recording medium with less abnormalities, abnormalities in protective film characteristics, and less substrate destruction, and improve production speed and yield.

[Brief description of the drawings]

FIG. 1 is a diagram showing a first embodiment and a second embodiment.

FIG. 2 is a diagram showing a conventional example.

FIG. 3 is a diagram showing a conventional example.

[Explanation of symbols]

 14 carbon target (sputter target) 15 electrode for plasma generation 16 DC power supply 18 AC power supply

Claims (2)

[Claims] An apparatus for manufacturing a magnetic recording medium, wherein a protective film is formed on a ferromagnetic metal thin film by sputtering while a non-magnetic substrate on which a ferromagnetic metal thin film is laminated is moved in a predetermined direction along a can roll. 3. The apparatus for manufacturing a magnetic recording medium according to claim 1, wherein a plurality of sputter targets for forming a protective film are provided in a vacuum chamber, and each of the sputter targets is connected to an independent power supply. 2. A method of manufacturing a magnetic recording medium, comprising forming a protective film on a ferromagnetic metal thin film by a plasma CVD method while running a non-magnetic substrate on which a ferromagnetic metal thin film is laminated in a predetermined direction along a can roll. An apparatus for manufacturing a magnetic recording medium, wherein a plurality of plasma generating electrodes for forming a protective film are provided in a vacuum chamber, and each of the plasma generating electrodes is connected to an independent power supply.