JPH11296847A - Method for evaluating magnetic recording medium, method for manufacturing magnetic recording medium, and apparatus for manufacturing magnetic recording medium - Google Patents

Abstract

PROBLEM TO BE SOLVED: To easily and accurately evaluate a film characteristic of a protective film in a state formed on a magnetic recording medium, and a magnetic recording medium for forming a protective film by using this evaluation method. It is an object of the present invention to provide a method of manufacturing a magnetic recording medium and an apparatus for manufacturing a magnetic recording medium. SOLUTION: An RF plasma CVD apparatus has a means for forming a magnetic film on a non-magnetic support, and an RF plasma CVD apparatus for forming a protective film such as a diamond-like carbon film on the magnetic film. The spectrum of the refractive index or absorption coefficient of the protective film is, for example, 19
Means such as a probe 16 for measuring at a wavelength of 0 nm or more and 900 nm or less are provided.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for evaluating a magnetic recording medium, a method for manufacturing a magnetic recording medium, and a device for manufacturing a magnetic recording medium, and more particularly, to measuring a refractive index and an absorption coefficient to form a protective film. The present invention relates to a magnetic recording medium evaluation method for evaluating characteristics, a magnetic recording medium manufacturing method using the same, and a magnetic recording medium manufacturing apparatus.

[0002]

2. Description of the Related Art Magnetic recording media for magnetic disk devices and digital video tape recorders often use magnetic recording media such as magnetic disks or metallized tapes using metal magnetic thin films. The configuration of these magnetic recording media will be described with reference to FIG. 1 which is a schematic configuration sectional view of the magnetic recording medium.

As shown in FIG. 1, a magnetic recording medium 1 generally has a non-magnetic support 2 such as polyethylene terephthalate and a magnetic film 3 such as an Fe—Co alloy film formed on the non-magnetic support 2. Further, a protective film 4 such as a carbon film is formed on the magnetic film 3. This protective film 4
In recent years, a diamond-like carbon film (hereinafter referred to as D) has been used for a magnetic disk in order to prevent the magnetic film 3 from being damaged by a head crash, and for a magnetic tape to have an excellent wear resistance due to sliding with a magnetic head.
Abbreviated as LC film. ) Has been formed.

[0004] The hardness of the protective film 4 such as the DLC film is closely related to the abrasion resistance characteristics, and it is extremely important to evaluate the hardness in order to know the film characteristics. In practice, directly measuring the hardness of the protective film 4 on the magnetic recording medium 1 such as a magnetic disk or a vapor-deposited tape requires that the thickness of the protective film 4 be several tens nm.
It is difficult to obtain measurement accuracy because the thickness is as thin as possible, and the hardness of the nonmagnetic support 2 is small, so that the influence on the protective film 4 is large.
The method of measuring hardness while applying a load using a needle-shaped test piece has limitations in measurement technology.

Conventionally, for example, a protective film 4 such as a DLC film of about 1 μm is formed on a Si substrate, and the indentation hardness of a needle-shaped test piece is measured by a micro-Vickers hardness meter.
Several tens nm deposited on the magnetic recording medium 1 under the same deposition conditions
The hardness of a carbon film having a thickness of the order was estimated. In addition to this, the abrasion resistance test of the protective film, and the CSS (contact start and stop) test for a magnetic disk, and the durability test such as a still (still image) test for a vapor-deposited tape. By a simple comparison, the film forming conditions that can bring out the optimum performance as the protective film 4 of the magnetic recording medium 1 have been determined.

However, the hardness of 1 μm in the hardness test and the actual hardness of several tens nm of the thickness of the protective film 4 of the magnetic recording medium 1 in the hardness test are not necessarily equal to each other. And it was difficult to estimate the actual hardness on the protective film 4.

As a method for evaluating the film characteristics of the protective film 4 such as a DLC film, there is a method of determining the composition ratio of the protective film 4. For example, the content ratio of hydrogen to carbon is determined by Raman spectroscopy and X-ray fluorescence analysis. It was estimated whether the atomic structure approximated the diamond structure by measuring by analysis such as the method. However, this analysis method also requires a sample to be prepared and analyzed after forming a film on a smooth test substrate such as a Si substrate, and the analysis is also complicated and requires many man-hours.

Therefore, an evaluation method capable of easily and accurately evaluating the film characteristics of the protective film 4 while being formed on the magnetic recording medium 1, a method of manufacturing the magnetic recording medium 1 using this evaluation method, and a magnetic recording method There has been a demand for an apparatus for manufacturing the medium 1 and a highly reliable magnetic recording medium 1 manufactured using these manufacturing methods and apparatuses.

[0009]

SUMMARY OF THE INVENTION In view of the above problems, the present invention provides a method for easily and accurately evaluating the film characteristics of a protective film in a state formed on a magnetic recording medium, and a method for evaluating the same. It is an object of the present invention to provide a method of manufacturing a magnetic recording medium in which a protective film is formed by using the method and an apparatus for manufacturing a magnetic recording medium.

[0010]

According to a first aspect of the present invention, there is provided a method for evaluating a magnetic recording medium, comprising: a non-magnetic support; a magnetic film formed on the non-magnetic support; In a method for evaluating a magnetic recording medium having a protective film such as a diamond-like carbon film, the curvature may be equal to that of a film forming roll for forming the protective film on the magnetic recording medium on which the protective film is formed. And supporting at least one of the refractive index and the absorption coefficient of the protective film by supporting the magnetic recording medium, for example, in a wavelength region of 190 nm.
As described above, the film characteristics such as the composition ratio or hardness of the protective film are evaluated by measuring at 900 nm or less.

According to a third aspect of the present invention, there is provided a method for evaluating a magnetic recording medium comprising a magnetic film formed on at least a non-magnetic support, and a protective film such as a diamond-like carbon film formed on the magnetic film. In the method for evaluating a recording medium, in the step of forming a protective film, while forming the protective film, at least one of the spectrum of the refractive index and the absorption coefficient of the protective film, for example, the wavelength region is 190 nm or more,
By measuring at 900 nm or less, film characteristics such as the composition ratio or hardness of the protective film are evaluated.

According to a seventh aspect of the present invention, there is provided a method for manufacturing a magnetic recording medium, comprising: forming a magnetic film on at least a non-magnetic support;
In a method for manufacturing a magnetic recording medium in which a protective film such as a diamond-like carbon film is formed on a magnetic film, the step of forming the protective film may include at least one of the spectrum of the refractive index and the absorption coefficient of the protective film. The method is characterized in that a step of forming a protective film is performed by measuring a region in a range from 190 nm to 900 nm to evaluate film properties such as a composition ratio or hardness of the protective film.

[0013] In the apparatus for manufacturing a magnetic recording medium according to the present invention, at least a means for forming a magnetic film on a non-magnetic support and a protective film such as a diamond-like carbon film are formed on the magnetic film. Means for forming a protective film, wherein the means for forming the protective film converts the spectrum of at least one of the refractive index and the absorption coefficient of the protective film into, for example, a wavelength region of 190 nm or more and 900 nm.
It is characterized by having means for measuring at m or less.

The operation of the above means will be described below.
According to the magnetic recording medium evaluation method of the present invention, by measuring the refractive index or absorption coefficient spectrum in a state formed on the magnetic recording medium, the composition ratio such as the hydrogen content of the protective film or the hardness. The film properties can be easily estimated in correspondence with other test results.

According to the method for evaluating a magnetic recording medium of the present invention, the spectrum of the refractive index or the absorption coefficient is measured in the step of forming the protective film, whereby the composition ratio such as the hydrogen content of the protective film or the hardness is measured. Can easily be estimated in correspondence with other test results.

According to the method of manufacturing a magnetic recording medium of the present invention, in the step of forming the protective film, the composition ratio such as the hydrogen content of the protective film or the hardness is measured by measuring the refractive index or absorption spectrum. The protective film under the optimum conditions can be formed while estimating the film characteristics of the sample easily in correspondence with other test results.

According to the apparatus for manufacturing a magnetic recording medium of the present invention, by providing means for measuring the refractive index and the absorption coefficient spectrum in the apparatus for forming the protective film, the composition ratio of the protective film such as the hydrogen content can be improved. Or, while feeding back the evaluation results of film characteristics such as hardness to film formation conditions on the spot,
A protective film can be easily formed under optimum conditions.

[0018]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments in which the method for evaluating a magnetic recording medium, the method for manufacturing a magnetic recording medium, and the apparatus for manufacturing a magnetic recording medium according to the present invention are applied to a vapor-deposited tape will be described with reference to FIGS. This will be described below with reference to FIG. However, the same components as those in the conventional example are denoted by the same reference numerals.

A DLC film, for example, is formed as a protective film 4 on the magnetic film 3 of the magnetic recording medium 1 which is a vapor-deposited tape. As a film forming method, a sputtering method, DC plasma CVD (Che
mical Vapor Deposition) method, RF plasma CVD method,
ECR (Electron Cyclotron Resonance) Plasma CVD
Method can be used. The raw material is a solid carbon target in the sputtering method, a gaseous hydrocarbon material such as methane, ethane and acetylene in the plasma CVD method, or a carbonaceous material gas such as liquid benzene, cyclohexane, toluene, xylene, methanol and ethanol. Hydrogen is gasified and used. The source gas may be used alone or in combination with a carrier gas such as an argon gas.

As an example of a film forming apparatus, an RF as shown in FIG.
The plasma CVD apparatus 5 will be described. In the RF plasma CVD apparatus 5, a raw material gas 9 such as methane or ethylene is supplied to a reaction tube 8 provided in a vacuum chamber 7 evacuated by a vacuum exhaust device 6, and the raw material gas 9
An RF power is supplied to the coil 10 from an F power supply (not shown) to generate a plasma by an RF electric field generated and react, and a film-shaped non-magnetic support such as polyethylene terephthalate supported in close contact with the film forming roll 11. Fe on 2
-Evaporation tape 17 on which magnetic film 3 such as Co thin film is formed
A protective film 4 such as a DLC film is formed thereon. The vapor deposition tape 17 housed in the unwinding roll 12 travels from the unwinding roll 12 via the guide rolls 13 and 14 and the film-forming roll 11 while being rotationally driven by the can-shaped film-forming roll 11. It is taken up by a take-up roll 15. The film forming roll 11 is a metal can roll having a radius r of, for example, 25 cm. A probe 16 for measuring the refractive index and the absorption coefficient of the spectrum is attached near the film forming roll 11 so that the measuring light is irradiated vertically onto the vapor deposition tape 17 which is in close contact with the film forming roll 11.

Using the above-mentioned RF plasma CVD apparatus 5, the protective film 4 of the DLC film is formed on the evaporation tape 17 on which the magnetic film 3 is formed or on the Si substrate. Evaporation tape 1
The film 7 is formed while running while being supported by the film-forming roll 11, and the Si substrate is fixed on the film-forming roll 11 and formed in a stationary state. Samples prepared under the above conditions are referred to as Examples 1 to 10 and Comparative Examples 1 to 4. The conditions for forming the DLC film for these samples will be described below.

[0022]

[0023]

[0024]

[0025]

[0026]

[0027]

[0028]

[0029]

[0030]

[0031]

[0032]

[0033]

[0034]

[0035]

The samples of the above Examples and Comparative Examples are subjected to the measurement of the spectrum of optical constants consisting of reflectance, transmittance, refractive index and absorption coefficient, hardness and still test.

Measurement of spectrum of optical constants The RF tape CVD apparatus 5 for forming the protective film 4 was prepared by using the vapor-deposited tapes 17 of the samples of Examples 1 to 10 and Comparative Examples 1 to 4.
3 having the same curvature r as the film forming roll 11 as shown in FIG. A probe 16 for measuring an optical constant is placed on a fixed support 18 substantially perpendicular to the center of the curved surface, and the refractive index and absorption coefficient spectra are measured. The measurement of the optical constant is performed by, for example, n & k Tech.
A nology, Inc. n & k analyzer is used. S
Regarding the i-substrate, in both the example and the comparative example, the probe 16 is installed in a direction perpendicular to the substrate, and the spectrum of the optical constant is measured. In this case, the refractive index and the absorption coefficient are determined from the spectrum of the reflectance or transmittance in the wavelength range of 190 nm to 900 nm of the measurement light. The spectrum in the wavelength range of 190 nm to 900 nm of the refractive index and the absorption coefficient is
Introduced by the theory of Forouhi et al. Details of this theory are introduced in the following documents. (Forouhi, Blo
omer, Phsy. Rev. B, 34, 7018, 1986)

Measurement of Hardness DL on the Si substrates of Examples 6 to 10 and Comparative Examples 3 and 4
The hardness of the sample on which the C film is formed is measured by a micro Vickers hardness tester.

Still test The durability of the sample with a DLC film formed on the vapor-deposited tape 17 of each of Examples 1 to 5 and Comparative Examples 1 and 2 was measured for sliding durability with a magnetic head. Assuming that one pass is a reproduction of a recording signal for one track, a decrease with respect to an initial output value after running 10 million passes is represented by dB, and a decrease of 3 dB or less is rejected. Pass is indicated by ○ and reject is indicated by ×.

The spectra of the reflectance R, the refractive index n and the absorption coefficient k, the hardness and the still test results of the above Examples and Comparative Examples are shown in FIGS. 4 to 8 and Table 1.

A DLC film was formed on the evaporation tape 17.
FIG. 4 shows the spectrum of the reflectance R of the sample of Example 1, and FIG. 5 shows the spectrum of the refractive index n and the absorption coefficient k. FIG. 6 shows the reflectance R spectrum of the sample of Comparative Example 1.
FIG. 7 shows the spectra of the refractive index n and the absorption coefficient k.
The spectra of the refractive index n and the absorption coefficient k of Example 6 and Comparative Example 3 in which a DLC film was formed on a Si substrate under the same conditions as above were almost the same as the spectra of Example 1 and Comparative Example 1, respectively. The characteristic values are shown.

For the samples of the above Examples and Comparative Examples, for example, the refractive index n _{0 at} a measurement wavelength of 635 nm,
Table 1 shows the measurement results of the hardness and still tests.

[0043]

[Table 1]

FIG. 8 shows the relationship between the refractive index n ₀ and the hardness on the Si substrate for the sample of the DLC film under the same film forming conditions from Table 1. Therefore, the results in Table 1 show that there is a correlation between the refractive index n _{0 at} a wavelength of, for example, 635 nm and the hardness and the still durability. That is, when the refractive index n ₀ becomes larger, the hardness also large, and the well is improved still durability characteristics. In the example in which the refractive index n ₀ is 1.7 or more, the Vickers hardness is 1000 G
Pa or more, and passed the still test. On the other hand, in the comparative example having a refractive index n ₀ of 1.6 or less, the Vickers hardness was small, and it failed the still test. From these results, it is found that the refractive index n ₀ at 635 nm is measured instead of the hardness or still test, and that the film characteristic as a DLC film is satisfied if the refractive index is 1.7 or more.

It is theoretically suggested that the spectrum pattern of the refractive index or the absorption coefficient is determined in accordance with the hydrogen content of the DLC film. Thus, the composition ratio such as the content ratio of hydrogen atoms to carbon can be known, and the formation state of a diamond structure or the like can be estimated. For example, 63
Refractive index n ₀ is a small hydrogen content in 2.1 or more at 5 nm, it has been found to have a structure in which the composition ratio is close to diamond, get the corresponding results of the hardness and still test. These results can be estimated from composition analysis such as another Raman spectroscopy or X-ray fluorescence spectroscopy. However, in these methods, preparation and measurement of a sample are very complicated and require many man-hours.

Next, an embodiment in which the spectrum of the optical constant is measured in, for example, an RF plasma CVD apparatus 5 for continuously forming a DLC film on the evaporation tape 17 will be described.

Measuring probe 16 of n & k analyzer
Is installed such that the measuring light is incident perpendicularly on the film forming roll 11 on which the evaporation tape 17 runs. At this time, the distance between the surface of the evaporation tape 17 and the measurement probe 16 is approximately 1 cm.
It is more preferable if it is within 5 mm. Using this apparatus, under the same conditions as in the above Examples and Comparative Examples, when a DLC film was produced on the vapor deposition tape 17, the spectrum of the optical constants of the DLC film during the manufacturing process was measured with the vapor deposition tape 17 in a stationary state. It was confirmed that the spectrum of the optical constant measured by attaching to the fixed support 18 and the spectrum of the optical constant of the sample in which the DLC film was formed on the Si substrate corresponded well to the measured value.

This is presumed to be because uniform tension is applied to the vapor deposition tape 17, the surface becomes smooth, and the scattering conditions of the measurement light become equal. Therefore,
Fixed support 1 having the same curvature r as film forming roll 11
By using No. 8, almost the same conditions as in the case of measuring the spectrum of the optical constants on the RF plasma CVD device 5 can be obtained. It can be seen that the spectrum can be measured, the sample can be made on a Si substrate, and the film characteristics of the DLC film can be confirmed.

Further, the film characteristics of the protective film 4 can be evaluated by measuring the optical constants of the protective film 4 such as a DLC film during the film forming process in a film forming apparatus such as the RF plasma CVD apparatus 5. If the evaluation result is fed back to the film forming conditions and the film is formed, the optimized protective film 4 can be easily manufactured. It should be noted that the present invention is not limited to the above embodiment.

[0050]

According to the method for evaluating a magnetic recording medium of the present invention, the film characteristics of the protective film can be easily and accurately evaluated with the protective film formed on the magnetic recording medium. ADVANTAGE OF THE INVENTION According to the manufacturing method and manufacturing apparatus of the magnetic recording medium of this invention, in the process of forming on a magnetic recording medium, a protective film can be formed easily and accurately evaluating the film characteristic of a protective film. .

[Brief description of the drawings]

FIG. 1 is a schematic sectional view of the configuration of a conventional magnetic recording medium.

FIG. 2 is a schematic sectional view showing the configuration of an RF plasma CVD apparatus according to the present invention.

FIG. 3 is a schematic sectional view showing a fixed support base for measuring an optical constant according to the present invention.

FIG. 4 is an explanatory diagram showing a reflectance spectrum of the first embodiment.

FIG. 5 is an explanatory diagram showing a spectrum of a refractive index and an absorption coefficient of Example 1.

FIG. 6 is an explanatory diagram showing a reflectance spectrum of Comparative Example 1.

FIG. 7 is an explanatory diagram showing a spectrum of a refractive index and an absorption coefficient of Comparative Example 1.

FIG. 8 is an explanatory diagram showing a relationship between a refractive index and hardness.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Magnetic recording medium, 2 ... Non-magnetic support, 3 ... Magnetic film, 4
... Protective film, 5 ... RF plasma CVD device, 6 ... Vacuum exhaust device, 7 ... Vacuum chamber, 8 ... Reaction tube, 9 ... Source gas, 10 ...
Coil, 11: film forming roll, 12: unwinding roll,
13, 14: guide roll, 15: take-up roll, 1
6 ... probe, 17 ... vapor deposition tape, 18 ... fixed support

Claims (13)

[Claims] 1. A method for evaluating a magnetic recording medium comprising at least a non-magnetic support, a magnetic film formed on the non-magnetic support, and a protective film formed on the magnetic film, Measuring the spectrum of at least one of the refractive index and the absorption coefficient of the protective film on the magnetic recording medium on which is formed, evaluating the film characteristics of the protective film. Evaluation methods. 2. The method for measuring the spectrum, wherein the measurement is carried out by supporting the magnetic recording medium so that the curvature is equal to that of a film-forming roll for forming the protective film. 2. The method for evaluating a magnetic recording medium according to item 1. 3. A method for evaluating a magnetic recording medium comprising at least a nonmagnetic support, a magnetic film formed on the nonmagnetic support, and a protective film formed on the magnetic film, Forming the protective film while measuring the spectrum of at least one of the refractive index and the absorption coefficient of the protective film to evaluate the film characteristics of the protective film. Evaluation method for magnetic recording media. 4. The wavelength range of the spectrum is 190 nm.
The thickness is not more than 900 nm.
Alternatively, the method for evaluating a magnetic recording medium according to claim 3. 5. The method for evaluating a magnetic recording medium according to claim 1, wherein the film characteristic of the protective film is one of a composition ratio and a hardness of the protective film. 6. The method for evaluating a magnetic recording medium according to claim 1, wherein the protective film is a diamond-like carbon film. 7. A method for manufacturing a magnetic recording medium comprising: forming a magnetic film on a non-magnetic support; and forming a protective film on the magnetic film, wherein the step of forming the protective film comprises: By measuring the spectrum of at least one of the refractive index and absorption coefficient of, while evaluating the film properties of the protective film,
A method for manufacturing a magnetic recording medium, comprising a step of forming the protective film. 8. The wavelength range of the spectrum is 190 nm.
The thickness is not more than 900 nm.
3. The method for manufacturing a magnetic recording medium according to claim 1. 9. The method according to claim 7, wherein the film property of the protective film is one of a composition ratio and a hardness of the protective film. 10. The method according to claim 7, wherein the protective film is a diamond-like carbon film. 11. A magnetic recording medium manufacturing apparatus having at least means for forming a magnetic film on a nonmagnetic support and means for forming a protective film on the magnetic film, wherein the protective film is formed. The apparatus for manufacturing a magnetic recording medium, wherein the means comprises means for measuring at least one of a refractive index and an absorption coefficient of the protective film. 12. The wavelength range of the spectrum is 190n.
The apparatus for manufacturing a magnetic recording medium according to claim 11, wherein the length is not less than m and not more than 900 nm. 13. The apparatus according to claim 11, wherein the protective film is a diamond-like carbon film.