JPH1064035A - Magnetic recording medium and method of manufacturing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve sliding durability of a magnetic recording medium by forming a thin film having specified or higher Vickers hardness on a metal magnetic thin film. SOLUTION: This magnetic recording medium 10 is obtd. by forming a magnetic layer 2 of a metal magnetic thin film on a nonmagnetic supporting body 1 as a base film, and further forming an inorg. coating film, namely a protective film 3 by sputtering on the magnetic layer 2. The protective film 3 consists of a thin film having >1400 Vickers hardness. As for the protective film 3, a carbon film or a film essentially comprising carbon is formed. The protective film 3 is formed by sputtering, and in the sputtering process, Kr gas or Xe gas or a mixture of these is used as a sputtering gas. Since the weight of Kr or Xe atom is large, the energy of plasma particles is increased to increase the kinetic energy of carbon particles sputtering from the target. Thus, a dense film can be formed.

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 an inorganic film (so-called protective film) is formed by sputtering on a magnetic metal thin film on a non-magnetic support, and a method of manufacturing the same.

[0002]

2. Description of the Related Art In the field of magnetic recording, with the increase in the amount of information to be recorded, there is a strong demand for higher density recording year by year. Along with this, instead of the so-called coating type medium in which conventional magnetic particles are dispersed in a binder and applied to a magnetic recording medium, ferromagnetic metal is plated or vacuum thin film forming means, for example, a vacuum evaporation method, a sputtering method. A so-called metal magnetic thin film type magnetic recording medium formed by an ion plating method is becoming mainstream.

[0003] The magnetic recording medium of this metallic magnetic thin film type is excellent in coercive force, squareness ratio and the like, and it is not necessary to mix a binder which is a non-magnetic material into a magnetic layer unlike a coating type medium. Density, that is, the amount of magnetization per unit volume can be increased, and the thickness of the magnetic layer can be made extremely thin as compared with a coating type medium. Excellent conversion characteristics. Further, the recording demagnetization is extremely small. Because of the above advantages, the metal magnetic thin film type magnetic recording medium is expected to become the mainstream magnetic recording medium for high density recording in the future.

[0004]

Incidentally, magnetic recording media using such a metal magnetic thin film as a magnetic layer, for example, magnetic disks such as hard disks, VTR media such as obliquely oriented vapor-deposited tapes, and magnetic media for data. Requires higher density recording, which increases the relative running speed between the magnetic recording medium and the magnetic head as the recording wavelength decreases, and reduces the spacing between the magnetic recording medium and the magnetic head. Of a base film for the purpose is required.

[0005] As a result, the frictional force between the magnetic head and the magnetic recording medium increases, and the shear stress generated in the magnetic recording medium increases. Therefore, in such a magnetic recording medium, a protective film is formed on the surface of the magnetic layer in order to improve sliding durability. Examples of the protective film include a carbon film, a SiO ₂ film, and a zirconia film. These films are formed by an RF sputtering method or a sputtering method using, for example, an argon gas.

However, when a film is formed by a sputtering method using an argon gas, the kinetic energy of the sputtered particles is small due to the small atomic weight of argon atoms, and the movement after reaching the thin film formation surface is small, so Voids and voids are likely to occur. Therefore, it has been difficult to improve the sliding durability only by forming a protective film on the surface of the film-formed magnetic layer.

[0007] In order to solve the above-mentioned problems, the present invention provides a magnetic recording medium capable of improving the sliding durability of a magnetic recording medium and enabling high-density recording, and a method of manufacturing the same.

[0008]

The magnetic recording medium of the present invention has a structure in which a thin film having a Vickers hardness of 1400 or more is formed on a metal magnetic thin film.

The method of manufacturing a magnetic recording medium of the present invention is a method of manufacturing a magnetic recording medium in which an inorganic film is formed on a magnetic metal thin film by a sputtering method, wherein a Kr gas, a Xe gas, or a mixed gas thereof is used as a sputtering gas. It is used.

According to the magnetic recording medium of the present invention, the Vickers hardness is 1400 on the metal magnetic thin film, that is, the magnetic layer.
By forming the above thin film, the sliding durability of the magnetic recording medium can be improved.

According to the method of manufacturing a magnetic recording medium of the present invention, an inorganic film is formed on a metal magnetic thin film by sputtering using Kr gas or Xe gas or a mixed gas of both as a sputtering gas. , Because the atomic weight is larger than the argon gas usually used as a sputtering gas,
The energy of gas atoms is large, and large kinetic energy can be given to sputtered particles. This allows
Diffusion (so-called migration) on the thin film formation surface (magnetic layer) is promoted, and voids and vacancies are reduced in the sputtered film. As a result, a dense, high-density, high-hardness sputtered film, that is, an inorganic film (a so-called protective film) can be formed.

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention has a Vickers hardness of 14
A magnetic recording medium in which 00 or more thin films are formed on a metal magnetic thin film is constituted.

Further, the present invention is configured such that the thin film is formed by a sputtering method in the magnetic recording medium.

According to the present invention, in the magnetic recording medium, the thin film is a thin film mainly containing carbon formed by a sputtering method.

In the method of the present invention, a Kr gas, a Xe gas, or a mixed gas of both gases is used as a sputtering gas in a method of manufacturing a magnetic recording medium in which an inorganic film is formed on a metal magnetic thin film by a sputtering method.

An embodiment of the magnetic recording medium of the present invention will be described below with reference to the drawings. Magnetic recording medium 10 shown in FIG.
A magnetic layer 2 made of a metal magnetic thin film is formed on a non-magnetic support 1 as a base film, and an inorganic film formed by a sputtering method, that is, a so-called protective film 3 is formed on the magnetic layer 2. In the present invention, in particular, a thin film having a Vickers hardness of 1400 or more is formed as the protective film 3.

The non-magnetic support 1 is made of a polymer support formed of a polymer material represented by polyesters, polyolefins, cellulose derivatives, vinyl resins, polyimides, polyamides, polycarbonates and the like. Form.

The magnetic layer 2 is formed on a magnetic recording medium for a hard disk by a sputtering method and on a vapor deposition tape by a vapor deposition method. Examples of the metal magnetic material constituting the magnetic layer 2 include ferromagnetic metals such as Fe, Co, and Ni, Co—Ni-based alloys, Co—Ni—Pt-based alloys, Fe—Co—Ni-based alloys, and Fe—Ni— B-based alloy, Fe-Co-B-based alloy, F
e-Co-Ni-B alloy, Co-Cr alloy (Co-
Cr-Ta, Co-Cr-Pt, etc.).

As the protective film 3, a carbon film or a film mainly composed of carbon is formed. The protective film 3 is formed by a sputtering method. At this time, K is used as a sputtering gas.
An r (krypton) gas, a Xe (xenon) gas, or a mixed gas of these gases is used. Since Kr and Xe are atoms having a large atomic number and the weight of the atoms is large, the energy of the plasma particles increases, and as a result, the kinetic energy of the carbon particles jumping out of the target increases. When the film reaches the sputtered film formation surface, energy enough to diffuse remains, so that it is easy to fill gaps in the sputtered film, voids and voids are not generated, and a dense film is formed. Further, the adhesion of the particles is increased, the film is hardly peeled off, water and oxygen are prevented from entering, and no rust is generated on the magnetic film.

Therefore, the sputtered film thus produced has a higher density and higher hardness than the protective film formed by the ordinary sputtering method using argon gas, thereby obtaining excellent sliding durability. it can. Further, by selecting the sputtering gas in this manner, the Vickers hardness of the protective film can be made 1400 or more.

The magnetic recording medium according to the present invention has a structure shown in FIG. 1 in which a top coat layer made of a rust inhibitor or a lubricant is formed on the protective film 3 (not shown). On the surface of the body 1 opposite to the surface on which the magnetic layer 2 is formed, a structure in which a back coat layer mainly composed of an antistatic agent and the like and a binder can be formed. In addition, any configuration and material used for this type of ordinary magnetic recording medium can be used.

Next, a magnetic recording medium 10 having the structure of FIG. 1 of the present invention was actually manufactured, and various characteristics were examined.

(Example 1) First, polyethylene terephthalate (P) was used as a polymer film to be the non-magnetic support 1.
ET) Prepare a film. Next, the non-magnetic support 1
The magnetic layer 2 made of Co—O was formed on the film of No. 1 while introducing oxygen gas by an oblique vapor deposition method.

The deposition conditions at this time are as follows. Ingot: Co ₁₀₀ vapor deposition incident angle: 45 ° to 90 ° Oxygen gas introduction amount: 0.55 liter / min Vacuum degree: 2 × 10 ⁻² Pa Magnetic layer film thickness: 160 nm Can be controlled by changing the feeding speed of the film or the input power of the electron gun.

Next, on the magnetic layer 2 thus formed on the non-magnetic support 1, a sputtering apparatus 11 shown in FIG.
Was used to form a carbon protective film as the protective film 3 by a sputtering method.

The sputtering apparatus 11 is a so-called magnetron sputtering apparatus, has a vacuum exhaust system 20 for evacuating the entire apparatus, and winds a film F in which a magnetic layer 2 is formed on a non-magnetic support 1. Unwinding roll 13 to be mounted
A take-up roll 14, a rotating support 12 for guiding the moving film F, a drum-shaped cooling can 19 for supporting and cooling the film F during processing, a gas inlet 18 for introducing sputter gas, Carbon target (cathode) 1 for forming protective film 3 by sputtering method
5

The magnet 1 is provided on the back side of the carbon target 15.
6, the magnet 16 applies a magnetic field to the carbon target 15 and its vicinity, and
A permanent magnet or an electromagnet is used to increase the plasma density around 5 to facilitate the collision of the plasma particles P. The carbon target 15 has a DC power supply 1
7, a potential of about -600 V is applied. Further, a sputtering gas is introduced from the gas inlet 18.

In the sputtering apparatus 11, the protective film 3 is formed as follows. First, the film F wound around the unwinding roll 13 is supplied to the cooling can 19 via the rotary support 12. The film F is transported along the drum-shaped cooling can 19, and the protective film 3 is formed in the vicinity of the carbon target 15 by the adhesion of the carbon particles C that have been ejected by the plasma particles P. The film F on which the protective film 3 is formed is wound around a take-up roll 14 via a rotary support 12.

The protective film 3 was formed on the magnetic layer 2 under the following conditions by this sputtering apparatus 11. The sputtering conditions at this time are shown below. Target: amorphous carbon Sputter gas: Kr gas Gas pressure during sputtering: about 0.3 Pa Carbon film thickness: 10 nm

The raw material of the tape thus produced is
The tape was cut into a predetermined tape width to produce a magnetic tape. In all the samples, the orientation angle of the easy axis of the magnetic layer 2 was 20 to 30 °.

(Example 2) A magnetic tape 10 was produced in the same manner as in Example 1 except that the sputtering gas for producing the carbon protective film was Xe gas.

Comparative Example 1 A magnetic tape 10 was produced in the same manner as in Example 1 except that the sputtering gas for producing the carbon protective film was Ar gas.

Next, a sample for measuring the hardness of the protective film was prepared separately from the magnetic tape 10 of each of these examples. First, P
A silicon substrate was stuck on a base film made of an ET film, and then, on this silicon substrate, the first embodiment was used.
To 2 and Comparative Example 1 with a carbon protective film having a thickness of 10
It was formed as 0 nm. This was used as a sample for hardness measurement in each example.

The hardness was measured using a Vickers hardness tester.
The Vickers hardness when the indentation depth was 50 nm was measured using MHA-400 (model name) manufactured by NEC.

Next, the sliding durability of the magnetic tape 10 of each example was measured. Sony 8mm VCR C
Using a VD-1000 (model name) modified for measurement, the output after running the magnetic tape 10 for 100 passes was measured to evaluate how many dB lower than the initial output (level down). Measurement). The measurement environment was 40 ° C, 3
0% R. H. And

The results of measurement of sliding durability and Vickers hardness are shown in Table 1 below.

[0037]

[Table 1]

As shown in Table 1, when the sputtering gas is Kr gas or Xe gas as in Examples 1 and 2,
Good sliding durability and Vickers hardness of 140
It turns out that it becomes 0 or more.

In the case of sputtering using Ar gas in Comparative Example 1, the level reduction was 2.0 dB, and the durability was not good. In addition, the Vickers hardness is as low as 1000, and the carbon protective film becomes brittle, so that carbon adheres to the magnetic head, causing a spacing loss and a problem such as a decrease in output.

Therefore, by using Kr gas and Xe gas as the sputter gas, a protective film having Vickers hardness of 1400 or more and excellent sliding durability can be formed.
The same effect can be obtained by using a mixed gas of Kr gas and Xe gas.

The magnetic recording medium and the method of manufacturing the same according to the present invention are not limited to the examples described above, but may take various other configurations without departing from the gist of the present invention.

[0042]

According to the above-described magnetic recording medium of the present invention, a thin film (protective film) having a Vickers hardness of 1400 or more is formed on a magnetic layer made of a metal magnetic thin film, whereby good sliding durability is obtained. A simple magnetic recording medium can be configured.

According to the method of manufacturing a magnetic recording medium of the present invention, the sputtering gas is selected from Kr gas, Xe gas, or a mixed gas thereof, so that a dense, high-density, high-hardness metal metal thin film can be formed. An inorganic coating (protective film) can be formed, and a magnetic recording medium with good sliding durability can be manufactured. Therefore, according to the present invention, a magnetic recording medium capable of high-density recording and having good durability can be manufactured.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram (cross-sectional view) of an example of a magnetic recording medium of the present invention.

FIG. 2 is a schematic configuration diagram of a sputtering apparatus used for forming a protective film.

[Explanation of symbols]

REFERENCE SIGNS LIST 1 non-magnetic support, 2 magnetic layer, 3 protective film, 10 magnetic recording medium, 11 sputtering device, 12 rotating support,
13 unwind roll, 14 take-up roll, 15
Carbon target (cathode), 16 magnet, 17 DC power supply, 18 gas inlet, 19 cooling can, 20 evacuation system, F film, P plasma particle, C carbon particle

Claims (4)

[Claims] 1. A magnetic recording medium wherein a thin film having a Vickers hardness of 1400 or more is formed on a metal magnetic thin film. 2. The magnetic recording medium according to claim 1, wherein said thin film is formed by a sputtering method. 3. The magnetic recording medium according to claim 1, wherein the thin film is a thin film mainly containing carbon formed by a sputtering method. 4. A method of manufacturing a magnetic recording medium in which an inorganic film is formed on a metal magnetic thin film by a sputtering method, wherein a Kr gas, a Xe gas, or a mixed gas of both is used as a sputtering gas. Production method.