JPH08273966A - Method for manufacturing magnetic recording medium - Google Patents

Abstract

PURPOSE: To provide a method for manufacturing a magnetic recording medium with a high coercive force and reproduction output and at the same time a small reproduction noise. CONSTITUTION: In a method for manufacturing a magnetic recording medium with CoPtCr magnetic layer, magnetic layers 3 and 5 with a composition of Co100-a-b Pta Crb (a and b indicate atom.%, 5<=a<=15, 8<=b<=20) are formed under a sputtering requirement of 1.0<P (inactive gas pressure) <3.0mTorr.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of manufacturing a magnetic recording medium used in a magnetic storage device or the like.

[0002]

2. Description of the Related Art Magnetic recording technology can be said to be based on a technology that has a long history and has matured. However, with the progress of the information society in recent years, the densification is accelerating and the performance is rapidly improving. Its importance is increasing.

In particular, in the field of magnetic disks (hard disks, floppy disks, etc.) used in peripheral storage devices of computers, the recording layer is becoming thinner to improve the recording density, and a thin film medium using a magnetic thin film is being used. Is approaching the age of. The semiconductor ICs are advancing at the same pace as the endless densification of the semiconductor ICs, and there is a momentum toward 1 Gbit / in ² in the future, and research and development including peripheral technologies are enthusiastically pursued.

As such a thin film recording layer, a CoPt type magnetic layer having a high coercive force has been attracting attention, and further, this CoPt type magnetic layer is divided by a nonmagnetic layer made of Cr to form a CoPt magnetic film / As a structure of the Cr non-magnetic film / CoPt magnetic film, a thin film recording layer in which noise during reproduction is reduced is known.

On the other hand, in general, a magnetic recording medium such as a hard disk is one in which an underlayer, a magnetic layer and a protective layer are sequentially formed on a non-magnetic substrate, and a head slider having a magnetic head mounted thereon is floated on the disk. While recording and reproducing. Therefore, in order to realize high density recording of the magnetic recording medium, it is becoming important to realize low head flying of the head slider in addition to high coercive force of the magnetic layer. That is, it is necessary to reduce the distance (spacing) between the magnetic head and the magnetic layer at the time of recording / reproducing to allow high-density recording / reproducing by moving the head slider at a low flying height.

Further, when the flying height is lowered, the repetitive operation (CSS: contact star) of switching between sliding running and floating running when the head slider starts and stops running is performed.
At the time of (t and stop), the physical and mechanical load applied to the magnetic head and the magnetic recording medium increases rapidly.
It is also necessary to improve the durability of the magnetic head and the magnetic recording medium (high CSS durability). Further, with the increase in recording density, it is more strictly required to reduce noise during reproduction.

By the way, in many current hard disks, an aluminum alloy substrate is used as a non-magnetic substrate, the surface of which is Ni-P plated and polished, and then textured to give an appropriate surface roughness. After that, the underlayer, the magnetic layer, the protective layer and the like are sequentially formed by the sputtering method. That is, unevenness resulting from surface roughness due to texture processing appears on the surface of the protective layer via the underlayer and the magnetic layer to prevent the head slider from adsorbing to the magnetic recording medium during CSS,
Alternatively, the frictional force between them is reduced.

However, it has been found that there is a limit to realizing the high density recording, low flying running and high CSS durability by this method. This is because the surface unevenness due to the texture is formed, and then the underlying layer and the magnetic layer having unevenness are formed following the unevenness, so that the incident angle of the sputtered particles varies depending on the location. Therefore, it is considered that one of the reasons is that crystals to be grown are not always formed favorably in the film formation process of the underlayer and the magnetic layer, and the increase in the coercive force of the magnetic layer is hindered. Further, since the aluminum alloy substrate has poor surface smoothness and the difference in height of the unevenness appearing on the disk surface due to the texture processing is large, the spacing cannot be reduced, and there is a limit to low flying travel. Further, the mechanical properties such as hardness of the aluminum alloy substrate are not always sufficient to satisfy the mechanical durability required for achieving low floating running and high CSS durability. In order to make the magnetic layer and the protective layer have good characteristics, it is necessary to perform physical and chemical treatments such as heat treatment at higher temperatures, but the aluminum alloy substrate is resistant to these treatments. It has been found that physical and chemical resistance such as corrosion resistance and corrosion resistance is not sufficient.

Further, recently, a magnetic recording medium using a glass substrate as a non-magnetic substrate has been attracting attention as a medium having a high possibility of easily realizing high density recording and low floating running. This is because glass has characteristics such as having sufficient hardness to cope with the recent reduction in the diameter and thinning of hard disks, and has excellent physical and chemical durability.
Moreover, the fact that the surface can be formed relatively easily with high plane accuracy (surface flatness), and therefore the spacing can be reduced and low flying travel can be easily achieved is suitable for realizing high density recording. This is because it is known that

[0010]

By the way, as described above, in order to realize high density recording, high coercive force,
It is important to realize low flying and high CSS durability, but this is not enough. In other words, with higher density recording, higher reproduction output is also required. Furthermore, with regard to noise during reproduction, a level that has not been a problem in the past has to be a problem. Also needs to be improved.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a method of manufacturing a magnetic recording medium which has a high coercive force, a high reproduction output, and a small noise during reproduction.

[0012]

The inventors of the present invention have conducted extensive studies to achieve the above-mentioned object, and as a result, have hitherto been considered to have optimum composition and optimum gas pressure (for example, JP-A-4-
229411, JP-A-2-37517, and JP-A-4-295625), CoPtC
Even if the r magnetic layer is formed, a magnetic recording medium satisfying all the above-mentioned required characteristics cannot be obtained, and in order to satisfy all of the current severe requirement characteristics, there is a combination of optimum composition and optimum gas pressure different from the conventional one. As a result, they have found that the required characteristics can be remarkably improved by this, and have completed the present invention.

That is, the method for producing a magnetic recording medium of the present invention is a method for producing a magnetic recording medium having a CoPtCr magnetic layer, wherein Co100-a-bPtaCrb (where a,
b is atomic%, and a magnetic layer having a composition of 5 ≦ a ≦ 15 and 8 ≦ b ≦ 20 is used, and the inert gas pressure P is 1.0 <P <
It is configured to be formed under a sputtering condition of 3.0 mTorr.

In the method for producing a magnetic recording medium of the present invention, in the method for producing a magnetic recording medium described above, preferably, the composition of the magnetic layer is Co100-a-bPtaCrb (however,
a and b represent atomic%, and 8 ≦ a ≦ 15 and 8 ≦ b ≦ 14)
And the magnetic layer is a CoPtCr-based magnetic film / Cr alloy-based non-magnetic film / CoPtCr-based magnetic film. The substrate temperature during film formation is 250 ° C. to 450 ° C. Underlayer is Al / Cr / CrM from substrate side
The structure is a base layer of the structure of o.

[0015]

In the present invention, since the CoPtCr magnetic layer having a specific composition is formed by the sputtering method under the pressure of a specific inert gas, the magnetic recording has a high coercive force and a high reproduction output, and the noise during reproduction is small. It became possible to obtain the medium.

This is due to the synergistic effect of setting the composition of the CoPtCr-based magnetic layer to be a specific composition and the inert gas pressure during sputtering to be a specific pressure, whereby the particle size of the magnetic particles in the magnetic film becomes small and the recording bit of the recording bit becomes small. Since the zigzag domain wall generated in the transition region is reduced, the medium noise is reduced (thus, the S / N ratio is improved), and at the same time, the magnetic separation degree between the magnetic grains is promoted, which improves the coercive force. It is believed that

The substrate temperature at the time of forming the magnetic layer is 25
By setting the temperature to 0 ° C to 450 ° C, the above effect can be further enhanced. In addition, the base layer is Al /
By using a Cr / CrMo underlayer or the like, the growth of crystal grains in the magnetic layer can be improved, and the above effect can be further enhanced.

The present invention will be described in detail below.

In the present invention, a magnetic recording medium is manufactured by forming a CoPtCr magnetic layer having a specific composition by a sputtering method under a specific inert gas pressure.

Here, the composition of the CoPtCr magnetic layer is
Co100-a-bPtaCrb (where a and b represent atomic%, 5 ≦ a ≦ 15, 8 ≦ b ≦ 20).

The CoPtCr magnetic layer contains CoPtC containing other components for the purpose of improving specific magnetic characteristics.
It may be rTa, CoPtCrB, CoPtCrNi, or the like.

The magnetic layer has a composition of CoP within the above range.
It may be a tCr-based magnetic film / Cr alloy-based non-magnetic film / CoPtCr-based magnetic film. By using such a divided magnetic layer, medium noise can be reduced as compared with the case of a single magnetic layer.

In this case, the Cr alloy nonmagnetic layer is
CrMo, CrV, CrMoZr, CrTa and the like are preferable. The content of other elements such as Mo in the Cr-based alloy is 2 to 3 considering the matching with the lattice spacing of the magnetic layer.
0 at%, preferably about 5 to 15 at% is suitable. Considering various magnetic characteristics of the magnetic recording medium, the thickness of the Cr-based alloy layer is preferably about 20 to 150 angstroms.

The material and film thickness of each magnetic film divided by the non-magnetic film may be the same or different.
Further, the magnetic layer may have a multilayer structure (for example, five layers) in which non-magnetic films and magnetic films are alternately laminated.

When the magnetic layer having the above composition is formed by the sputtering method, the inert gas pressure P is 1.0 <P <3.0 m.
Torr.

As the sputtering method, DC magnetron sputtering, RF magnetron sputtering and the like can be used, but DC magnetron sputtering is preferable from the viewpoint of operability and cost. As the inert gas, Ar gas is usually used because it is inexpensive and does not easily react with other substances.

When any one of the composition of the CoCrPt magnetic layer and the inert gas pressure exceeds the above range, the required characteristics of coercive force, reproduction output and noise are poor and all required characteristics are satisfied. Things will be difficult. In order to obtain such an effect more remarkably, in the case of a single magnetic layer, Co100-a-bPtaCrb (however, a, b
Indicates atomic% and has a composition of 8 ≦ a ≦ 15, 8 ≦ b ≦ 14),
In the case of a split magnetic layer, Co100-a-bPtaCrb
(However, a and b represent atomic%, and 10 ≦ a ≦ 15 and 11 ≦ b ≦
18) and 1.5 <P <2.0 mTorr
It is more preferable to set the inert gas pressure range to.

The substrate temperature during film formation of the magnetic layer is 250 ° C. to 4 ° C.
It is preferably 50 ° C. This is because the substrate temperature at the time of forming the magnetic layer contributes to the improvement of the required characteristics.
Note that this temperature range is higher than the conventionally known substrate temperature range.

The above-mentioned magnetic layer is usually formed on a non-magnetic substrate after forming an underlayer on the nonmagnetic substrate.

Here, examples of the non-magnetic substrate include a glass substrate, a crystallized glass substrate, a surface strengthened glass substrate, an aluminum substrate, an aluminum alloy substrate, a ceramic substrate, a plastic substrate, a Si substrate, a Ti substrate, and a carbon substrate. However, it is preferable to use a glass substrate, a crystallized glass substrate, a surface-strengthened glass substrate, or the like.

As described above, this is because the glass substrate or the like has such characteristics that it has sufficient hardness to cope with the recent reduction in the diameter and thickness of hard disks, and has excellent physical and chemical durability. Moreover, it is more suitable for realizing high-density recording that the surface can be formed relatively easily with high plane accuracy, and therefore the spacing can be reduced and the low-flying travel can be easily achieved. .

Specific examples of the glass substrate include aluminosilicate glass, aluminoborosilicate glass, borosilicate glass, quartz glass and soda lime glass. Chemically tempered glass is, for example,
It can be obtained by replacing Li and Na ions in the glass with Na and K ions having a larger ionic radius than those by ion exchange to generate a strong compressive stress in the glass surface layer to increase the strength.

Cr and CrMo are used as the underlayer of the magnetic layer.
Etc. can be used, but Al / Cr / C from the substrate side
An underlayer having a structure of rMo is particularly preferable. This is because when a magnetic film having the above composition is formed on a glass substrate, Cr or C is used.
This is because better magnetic properties can be obtained as compared with the case where rMo alone is used as the base and the case where the Al base is not formed.

Instead of CrMo (third underlayer), Cr-based alloys such as CrV, CrMoZr and CrTa may be used. The content of other elements such as Mo in the Cr-based alloy is appropriately 2 to 30 at%, preferably 5 to 15 at% in consideration of the matching with the lattice spacing of the magnetic layer. Considering various magnetic characteristics of the magnetic recording medium, the thickness of the Cr-based alloy layer is preferably about 20 to 150 angstroms. The underlayer such as CrMo which is in direct contact with the magnetic layer affects the crystal growth of the magnetic layer and the magnetic characteristics.

Further, instead of Cr (second underlayer), T
A non-magnetic material such as i, W, Mo, Ta, Zr, Cu, Zn, In or Sn can also be used. The second underlayer can be composed of two or more layers.

Further, instead of Al (first underlayer),
Materials such as Si, Pb, Cu, Ga and In can also be used.

It is preferable to form a protective layer and a lubricating layer on the magnetic layer.

The protective layer is provided on the magnetic layer for the purpose of protecting the magnetic layer from being destroyed by the sliding contact of the magnetic head.

Examples of the protective layer include a Cr film, a Cr alloy film (CrMo, etc.), a carbon film, a zirconia film, a silica film, SiN, SiC, Si-O-N, Si-O-C and the like. These protective films may be a single layer, or may be a multi-layer structure composed of the same or different types of films.

Another protective layer can be formed on the protective layer. For example, it is possible to form a silicon oxide (SiO ₂ ) film by diluting tetraalkoxylane with an alcohol solvent and applying it on the protective layer, followed by baking. in this case,
By dispersing hard particles such as silica particles having a uniform particle size in a solvent, high wear resistance can be imparted,
It is possible to prevent the head from adsorbing, and further reduce the spacing loss because the protrusions (texture) due to the silica fine particles are uniform.

The protective layer is made of Cr / SiO.
_{A 2} (wet) multilayer protective layer is preferred, in which case C
The r film plays a role of impact resistance and chemical protection, and SiO film
_{The two} films play a role of wear resistance and corrosion resistance. Instead of Cr, Mo, Ti, TiW, CrMo, Ta, W, S
A non-magnetic material such as i or Ge can also be used.

The lubricating layer is provided on the protective layer for the purpose of reducing the frictional resistance between the magnetic head and the surface of the medium.

The lubricating layer is generally formed by diluting perfluoropolyether (PFPE), which is a liquid lubricant, with a solvent such as Freon, coating it on the surface of the medium by a dipping method, etc., and performing heat treatment as necessary. To do. As the lubricant, in addition to the above, a conventionally known or commercially available lubricant such as a fluorocarbon liquid lubricant or a lubricant composed of an alkali metal salt of sulfonic acid can be used.

A suitable film thickness of the lubricating layer is about 10 to 30 Å. This is because if it is less than 10 angstroms, the wear resistance is insufficient and the lubricating life is shortened, and if it exceeds 30 angstroms, the wear resistance is not improved, and the problem of magnetic head adsorption occurs. is there.

The underlayer, the magnetic layer, and the Cr protective layer can be formed by using a static facing type sputtering device or the like, but it is preferable to form them continuously by using an inline type sputtering device. In this case, it is preferable to provide a shield plate between the targets in order to avoid an influence between adjacent plasmas.

[0046]

EXAMPLES The present invention will be described in more detail based on the following examples.

Example 1 In this example, as shown in FIG. 1, an underlayer 2, a first magnetic film 3, a nonmagnetic film 4, a second magnetic film 5, a protective layer 6 and a lubrication layer were formed on a glass substrate 1. A magnetic disk is manufactured by sequentially stacking layers 7.

The magnetic disk shown in FIG. 1 is intended to reduce noise by dividing a CoPt-based magnetic layer exhibiting a high coercive force by a non-magnetic layer, and an MR head (magnetoresistive head). ), It can be suitably used as a magnetic disk.

First, a glass substrate made of aluminosilicate glass chemically strengthened by ion exchange and having a diameter of 2.5 inches and a thickness of 0.9 mm has a surface roughness (Ra) of 30 Å (Rmax of 300) by precision polishing on both sides.
(Angstrom).

The glass substrate is a substrate holder (pallet)
2 and the pallet 18 is introduced into the charging chamber 11 of the in-line type DC magnetron sputtering device 10 shown in FIG. 2, and then the charging chamber 11 is evacuated from the atmospheric state to a vacuum degree equal to the vacuum degree of the sputtering chamber (vacuum chamber) 12. Exhaust.
Then, the partition plate 14 is opened and the pallet 18 is introduced into the first vacuum chamber 12a. In the first vacuum chamber 12a, the glass substrate mounted on the pallet 18 is heated by the lamp heater 19 under the heating condition of 375 ° C. for 2 minutes, and then the pallet 18 is moved at a conveyance speed of 50 cm / min to face each other. It passes through between the arranged targets 15a and 15b in the discharged state. The targets are arranged in the order of Al and Cr in the transport direction of the pallet, and the Al base film 2a (film thickness 50 Å) and the Cr base film 2b ₁ ( The film thickness is 300 angstrom).

Next, the pallet 18 is moved to the second vacuum chamber 12b via the port 21, and the substrate is heated again by the heater 20 arranged in the second vacuum chamber 12b. The heating conditions are 350 ° C. and 1 minute. afterwards,
Cr target 15c, CrMo target 15d, C
oPtCr target 15e, CrMo target 15
f, CoPtCr target 15g, Cr target 1
Targets 15c placed in the order of 5h and in a discharged state
The pallet 18 is passed at a conveyance speed of 50 cm / min for a period of up to 15 hours. Then, the Cr underlayer film 2b ₂ (thickness 300 Å), the CrMo underlayer film 2c (thickness 100 Å), the CoPtCr first magnetic film 3 (thickness 120 Å), and the CrMo nonmagnetic layer are arranged in the order of the arranged targets. Film 4 (film thickness 50 Å), CoPtCr second magnetic film 5 (film thickness 120)
Å), and the Cr first protective layer 6a (film thickness 50 Å) are laminated in this order.

The composition ratio of the CrMo target 15d was Cr98 at% and Mo2 at%, and the composition ratio of the CrMo target 15f was Cr95 at% and Mo5 at%. Further, the CrMo targets 15d and 15f were both sputtered at a low input power of 500W. The composition ratios of the CoPtCr targets 15e and 15g are Co77 at%, Pt12 at% and Cr.
It was 11 at%. Furthermore, the ultimate pressure (vacuum degree) in the vacuum chamber was set to 5 × 10 ⁻⁶ torr, Ar gas was introduced, and sputtering was performed at 2 mtorr (2 × 10 ⁻³ torr).

After the film formation by sputtering is completed, the substrate is
Si is obtained by immersing in an organic silicon compound solution (mixture of water, IPA and tetraethoxysilane) in which fine silica particles (grain size 100 angstroms) are dispersed, and baking the resulting solution.
A second protective layer 6b made of O ₂ was formed.

Finally, on the second protective layer 6b, a lubricant made of perfluoropolyether (AM manufactured by Montedison Co., Ltd.) is used.
2001) to form a lubricating layer 7 having a thickness of 20 angstrom.

The magnetic disk thus obtained was evaluated for coercive force, reproduction output and noise. Table 1 shows the results.

Examples 2 to 11 A magnetic disk was prepared in the same manner as in Example 1 except that the composition ratio of the CoPtCr targets 15e and 15g and the Ar gas during sputtering were changed to the values shown in Table 1.
Similar evaluation was performed. Table 1 shows the results.

Comparative Examples 1 to 8 Magnetic disks were prepared in the same manner as in Example 1 except that the composition ratio of CoPtCr targets 15e and 15g and the Ar gas during sputtering were changed to the values shown in Table 1.
Similar evaluation was performed. Table 1 shows the results.

Comparative Examples 9 to 12 In Example 1, CrMo target 15 was prepared.
The CoPtCr magnetic layer was divided by Cr using a Cr target instead of f (Comparative Example 9), the Al underlayer film 2a was not formed (Comparative Example 10), and the Cr underlayer film 2 was formed.
b ₁ and 2b ₂ were not formed (Comparative Example 11), Cr
The Mo base film 2c was not formed (Comparative Example 12),
A magnetic disk was manufactured in the same manner as in Example 1 except for the above, and the same evaluation was performed. Table 1 shows the results.

[0059]

[Table 1]

As is clear from Table 1, even if one of the composition of the magnetic film and the Ar gas pressure at the time of sputtering the magnetic film is in the preferable range, all required characteristics of coercive force, reproduction output and noise are satisfied. It is difficult to satisfy the above requirements, and it can be understood that all required characteristics can be satisfied only when both are in the preferable range. That is, it can be seen that the optimum gas pressure differs when the composition is different, and that all required characteristics can be remarkably improved for the first time by combining the specific composition and the specific gas pressure.

Examples 12 to 21 The targets 15f and 15g were not used (no power was applied), the magnetic layer was composed of a CoPtCr single magnetic film (thickness: 500 Å), the composition ratio of the CoPtCr target 15e, and sputtering. Ar gas of Table 2
A magnetic disk for a thin-film head was manufactured in the same manner as in Example 1 except that the value was changed to the value shown in, and the same evaluation was performed. The results are shown in Table 2.

Comparative Examples 13 to 20 Magnetic disks were prepared in the same manner as in Examples 11 to 20 except that the composition ratio of the CoPtCr target 15e and the Ar gas at the time of sputtering were changed to the values shown in Table 2. An evaluation was made. The results are shown in Table 2.

[0063]

[Table 2]

As is clear from Table 2, the magnetic layer is CoP.
It can be seen that even in the case of the tCr-only magnetic film, all the required properties can be satisfied only when both the composition of the magnetic film and the Ar gas pressure during sputtering of the magnetic film are in the preferable ranges.

The coercive force (Hc) was measured by cutting out a sample of 8 mmφ from the manufactured magnetic disk, applying a magnetic field in the film surface direction, and measuring the maximum external applied magnetic field of 10 kOe with a vibrating sample magnetometer.

The recording / reproducing characteristics (reproducing output and medium noise) were measured as follows. That is, with respect to the magnetic disk for MR head (Examples 1 to 11 and Comparative Examples 1 to 12) shown in Table 1, the obtained magnetic disk for MR head was used and the flying height of the magnetic head was 0.055.
Using a μm MR head, the relative speed between the MR head and the magnetic disk was set to 6 m / s, and the linear recording density was 80 kfci.
The recording / reproducing output at (a linear recording density of 80,000 bits per inch) was measured. Also, carrier frequency 1
The noise spectrum at the time of signal recording / reproduction was measured by a spectro-analyzer at 0 MHz with a measurement band of 18 MHz. As an MR head, the number of coil turns is 3
0, track width 4.8 on write / read side respectively
/3.5 μm, magnetic head gap length 0.43 / 0.3
A 1 μm MR head was used.

Regarding the thin-film head magnetic disks (Examples 12 to 21 and Comparative Examples 13 to 20) shown in Table 2, the obtained thin-film head magnetic disks were used and the flying height of the magnetic head was 0.055 μm. With the thin film head of
The relative speed between the MR head and the magnetic disk is 6 m / s,
The recording / reproducing output at a linear recording density of 70 kfci (linear recording density of 70,000 bits per inch) was measured.
The carrier frequency is 8.5 MHz and the measurement band is 15
The noise spectrum at the time of recording / reproducing a signal was measured by a spectroanalyzer as MHz. As the thin film head, a thin film head having 50 coil turns, a track width of 6 μm and a magnetic head gap length of 0.25 μm was used.

Although the present invention has been described above with reference to the preferred embodiments, the present invention is not necessarily limited to the above embodiments.

[0069]

As described above, according to the method of manufacturing a magnetic recording medium of the present invention, it is possible to obtain a magnetic recording medium which has a high coercive force and a high reproduction output and has a small noise during reproduction.

[Brief description of drawings]

FIG. 1 is a schematic cross-sectional view showing an example of a magnetic recording medium manufactured by the present invention.

FIG. 2 is a plan view showing an in-line type sputtering device for a magnetic disk used in an example.

[Explanation of symbols]

 1 Glass Substrate 2 Underlayer 3 First Magnetic Film 4 Nonmagnetic Film 5 Second Magnetic Film 6 Protective Layer 7 Lubricating Layer 10 In-line Sputtering Equipment 15 Target 16 Shield Plate 18 Pallet

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Kiyoshi Sato 2-7-5 Nakaochiai, Shinjuku-ku, Tokyo Inside Hoya Co., Ltd. (72) Hisao Kawai 2-7-5 Nakaochiai, Shinjuku-ku, Tokyo Hoya Corporation

Claims (5)

[Claims] 1. A method of manufacturing a magnetic recording medium having a CoPtCr-based magnetic layer, comprising: Co100-a-bPtaCrb (where a and b represent atomic%, and 5 ≦ a ≦ 15 and 8 ≦ b ≦ 20 are satisfied). A method for producing a magnetic recording medium, characterized in that the magnetic layer having the composition (1) is formed under a sputtering condition where the inert gas pressure P is 1.0 <P <3.0 mTorr. 2. The composition of the magnetic layer is Co100-a-bPtaCr
b (however, a and b represent atomic%, 8 ≦ a ≦ 15, 8 ≦ b ≦ 1
4. The method for manufacturing a magnetic recording medium according to claim 1, wherein 3. The method for manufacturing a magnetic recording medium according to claim 1, wherein the magnetic layer is a CoPt-based magnetic film / Cr alloy-based non-magnetic film / CoPtCr-based magnetic film. 4. The substrate temperature during film formation of the magnetic layer is 250.degree.
The method of manufacturing a magnetic recording medium according to claim 1, wherein the temperature is 450 ° C. 5. The underlayer of the magnetic layer is made of Al / C from the substrate side.
5. The method of manufacturing a magnetic recording medium according to claim 1, wherein the underlayer has a structure of r / CrMo.