JPH05258271A - Magnetic recording medium - Google Patents

Abstract

PURPOSE:To enhance durability by forming a perpendicular magnetic anisotropic film of a specified oxide on a magnetic film of a specified alloy. CONSTITUTION:A magnetic film of a Co-Ni-Cr alloy having plane anisotropy is formed by sputtering on a nonmagnetic substrate such as a sheet of polyimide, polyester or other org. polymer, a stainless steel sheet or a glass sheet and a perpendicular magnetic anisotropic film of a partially oxidized Fe-Co alloy or partially oxidized Co is further formed on the magnetic film under the conditions of -30 to +200 deg.C temp. of the substrate, 1-10mTorr pressure of gaseous Ar and 10-10,000Angstrom /min rate of deposition. The durability of the resulting magnetic recording medium can be considerably enhanced.

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 capable of high density recording, and more particularly to a magnetic recording medium suitable for a video floppy disk used for still video, data disk and the like.

[0002]

2. Description of the Related Art In recent years, a small floppy disk having a diameter of 2 inches has been put to practical use and used for image recording, data recording and the like. These discs are used on one side and have a capacity of 50 still images for image recording and about 1 MB for data recording. The magnetic material used for these disks is Fe-based alloy powder or the like, and the coercive force Hc is set to about 1000 to 1500 Oe.

[0003]

However, in order to further increase the capacity and the image quality of the 2-inch disk, the current coatable medium is insufficient in the C / N ratio, and There is a limit to improving the coercive force. On the other hand, in recent years, a metal thin film type medium has attracted attention as a medium capable of high density recording and is being put to practical use. As a method that enables higher density recording, Co
The perpendicular recording method using −Cr as a recording layer is also being studied for practical use. In the case of a head-contact type floppy disk, these metal thin film media are apt to wear due to the sliding of the media and the head, and there is a problem in durability.

[0004]

SUMMARY OF THE INVENTION The present inventors have arrived at the present invention as a result of earnest research as a solution to the above problems in view of the above circumstances. That is, the first aspect of the present invention is to provide a magnetic film made of a Co-Ni-Cr alloy having in-plane anisotropy on a non-magnetic substrate, and further to provide a partial oxide of Fe-Co alloy or Co. A second aspect of the present invention provides a magnetic recording medium provided with a perpendicular magnetic anisotropy film made of a partial oxide on at least one surface of a polyimide film having a thickness of 25 to 30 μm. A magnetic film made of a Co-Ni-Cr alloy having a directionality, a perpendicular magnetic anisotropy film made of a partial oxide of Fe-Co alloy or a partial oxide of Co are sequentially formed to a total film thickness of 2000 to 4000 Å. The contents are the magnetic recording media for electronic still cameras that are formed.

According to the present invention, a horseshoe-shaped magnetization mode is formed by combining an in-plane recording layer and a perpendicular recording layer, and a high C / N ratio can be obtained in a wide range of recording density from low density to high density. Since the dynamic friction coefficient of the Fe-Co or Co partial oxide layer, which is an oxide, is low, the durability is also improved.

As the non-magnetic substrate used in the present invention,
Plates, films and sheets of organic polymers such as polyimide and polyester, and metal plates such as aluminum and stainless steel,
A glass plate or the like is used.

The magnetic recording medium of the present invention is manufactured by a thin film manufacturing method in a broad sense such as a sputtering method and a vapor deposition method. Hereinafter, a manufacturing method by a sputtering method, particularly a high frequency sputtering method will be described. In the present invention, for a magnetic film made of a Co—Ni—Cr alloy having in-plane anisotropy, the substrate temperature is room temperature to 350 ° C., the argon gas pressure is 1 to 20 mTorr,
A deposition rate of 100 to 10,000 Å / min is preferably obtained under sputtering conditions. Further, if a Cr film or the like is provided as a non-magnetic underlayer under the Co-Ni-Cr alloy magnetic film, it becomes 800 to 15
A large coercive force of about 00 Oe can be obtained. This nonmagnetic underlayer also has the effect of hardening the medium to some extent and improving durability. The thickness of the Co-Ni-Cr alloy magnetic film is 500 to 4000.
The range of Å is preferable. If it is thinner than 500Å, scratches are likely to occur, and if it is thicker than 4000Å, there is a tendency for rotation failure.

Regarding the partial oxide film of the Fe--Co alloy which is the perpendicular recording layer of the present invention, the substrate temperature is −30 to 200 ° C., the argon gas pressure is 1 to 10 mTorr, and the deposition rate is 10 to 1000.
It is preferably manufactured under the condition of 0Å / min. The substrate temperature is determined in consideration of the heat resistance of the substrate film and the economical efficiency of using a heating or cooling device. The lower the argon gas pressure, the greater the vertical anisotropy, but if it is too low, the discharge will not be stable.
The thickness of the partial oxide film of Fe-Co alloy is 300 ~ 1000Å
Is preferred. If the thickness is less than 300Å, the output at high density is small and the durability is insufficient.
If it is thicker, the recording / reproducing characteristics tend to deteriorate.

The magnetic properties of the partial oxide film of the Fe--Co alloy, especially the saturation magnetization, the perpendicular magnetic anisotropy and the coercive force, are mainly determined by the Co concentration and the oxygen concentration. When the Co composition is 30 to 70 atomic% [Co / (Co + Fe)], a medium having a large perpendicular magnetic anisotropy can be obtained. More preferably, 40 to 60 atomic%
It shows the maximum perpendicular magnetic anisotropy before and after. The oxidation rate, which is another factor that determines magnetism, is preferably 50 to 85%. The oxidation rate defines saturation magnetization, perpendicular magnetic anisotropy, and coercive force. When the oxidation rate is increased, the saturation magnetization linearly decreases, and conversely the perpendicular magnetic anisotropy and coercive force increase. The coercive force and perpendicular magnetic anisotropy should be appropriate values according to the head used. The oxidation rate can be controlled by the oxygen introduction amount or oxygen partial pressure during sputtering. By controlling the contents of both cobalt and oxygen, the saturation magnetization is 300-
A magnetic film having a magnetic field of 700 emu / cc, a perpendicular anisotropic magnetic field of 3 to 7 kOe and a perpendicular coercive force of 200 to 1000 Oe can be obtained.

Next, as for the method of forming the Co partial oxide film, it is preferably formed by so-called DC reactive sputtering in an oxygen atmosphere with Co as a target. The magnetic properties are determined by the argon gas pressure and the amount of O ₂ introduced.
Saturation magnetization is determined by the amount of oxygen introduced, and is adjusted to 300 to 700 emu / cm ³ by 50 to 75% oxidation. The thickness of the Co partial oxide film is preferably 300 to 1000Å as in the case of the Fe-Co alloy partial oxide film. By increasing the argon gas pressure in this region, a medium having excellent perpendicular anisotropy can be obtained and the perpendicular coercive force can also be increased. Vertical anisotropy magnetic field 3-5kOe, vertical coercive force 500-1
A film of 500 Oe is obtained.

The first important point in constructing the magnetic recording medium of the present invention is the coercive force of the Co--Ni--Cr alloy magnetic film. The larger the coercive force, the larger the reproduction output, but it is usually preferable to set it to about 500 to 1500 Oe depending on the specifications of the head. Furthermore, as a non-magnetic underlayer
It is easier to control the coercive force by providing the Cr film and then providing the Co—Ni—Cr alloy magnetic film thereon, and it is also useful for improving the durability. The Cr film has a bcc structure, the Co-Ni-Cr layer grows epitaxially on this, and the C-axis has a tilted crystal structure to exhibit anisotropy in a direction parallel to the plane. The thickness of the Cr film can be changed within the range of 300 to 3000Å.

The second important point in constructing the magnetic recording medium of the present invention is the thickness of the nonmagnetic substrate and the magnetic layer. The stiffness as a medium is preferably adjusted to 2.5 to 5 g · mm. For that purpose, for example, when a film having a tensile elastic modulus of about 700 kg / mm ² is used as a non-magnetic substrate, a thickness of 25 to 30 μm is used. A film is suitable.

The total thickness of the magnetic layer is preferably 800 to 5000Å, more preferably 2000 to 4000.
Å is preferred. If the thickness of the partial oxide film is increased, the durability is improved, but the reproduction output especially at low recording density is reduced. On the other hand, when the film thickness of Co-Ni-Cr is increased and the film thickness of the partial oxide film is decreased, the reproduction output of low recording density is improved, but the reproduction output of high recording density is decreased and durability is improved. Also decreases. On the other hand, if the respective film thicknesses are too large, the disc becomes hard and sliding with the head becomes unstable, and stable recording / reproducing cannot be performed. As an example, Cr film 1000
Å, Co-Ni-Cr film 1750 Å, Fe-Co partial oxide film 50
The 0Å medium showed excellent recording density characteristics and durability.

Further, on at least one surface of a polyimide film having a thickness of 25 to 30 μm, a Cr film as a non-magnetic underlayer,
Magnetic film made of Co-Ni-Cr alloy with in-plane anisotropy, Fe-
A medium in which a partial oxide of a Co alloy or a perpendicular magnetic anisotropic film of a partial oxide of Co is sequentially formed to have a total film thickness of 2000 to 4000 Å is suitable as a magnetic recording medium for an electronic still camera. With such a medium structure, a proper stiffness can be obtained for the floppy disk drive of the current electronic still camera, a stable head touch can be obtained, and excellent recording / reproducing characteristics, that is, recording / reproducing superior to the current metal coated medium. The characteristics can be realized. This stiffness maximizes the durability of both the head and the medium. The back surface may have the same structure as the front surface, but may be thin as long as it is durable enough to withstand sliding with the drive pad.

The conventional metal thin film type medium has a difficulty in durability, and means for providing an inorganic or organic protective layer has been taken.
However, with such a means, the spacing originating from the non-magnetic layer is generated between the head and the medium, and the recording density characteristic is impaired. Therefore, the thickness of the protective layer is limited to 200 Å, and sufficient durability can be obtained. The reality was that there was no such thing.

On the other hand, the magnetic recording medium of the present invention has a hard surface layer of a partial oxide film, a small friction coefficient, and excellent durability against sliding with the head. Moreover, since the partial oxide film itself is a magnetic film having perpendicular magnetic anisotropy, spacing is not generated. That is, since the recording layer itself also functions as a protective layer, it has both sufficient durability and recording / reproducing characteristics. The recording / reproducing of the medium of the present invention can obtain a high reproducing output and a high recording density particularly when a ring head is used.

In the present invention, in order to increase the coercive force, the nonmagnetic substrate can be sputtered in an Ar atmosphere. FIG. 1 shows the relationship between the coercive force and the sputtering process time. It can be seen that the coercive force increases with the processing time as the sputtering process proceeds. When the film is observed with an electron microscope, it is found that minute unevenness is generated by the sputtering process. The minute irregularities that have been effective in increasing the coercive force have a processing time of 20 to 50 minutes and a depth of 0.02 to 0.1 when processed with a sputtering power of 100 W.
μm, and the width is 0.03 to 0.5 μm. If the treatment time is shorter than this range, the surface irregularities are too small to provide sufficient coercive force.On the other hand, if the treatment time is longer, the surface irregularities become too large and the mechanical strength of the film surface deteriorates significantly and the coercive force also decreases. Tend to do. Therefore, in the present invention, the surface fine unevenness generated when the sputtering treatment is performed in an Ar atmosphere to increase the coercive force has a depth of 0.02.
.About.0.1 .mu.m and width 0.03 to 0.5 .mu.m are preferable.

In order to increase the coercive force, Co-Ni-
Sm can be added to the Cr film. Figure 2 shows the relationship between the coercive force and the amount of Sm added. It can be seen that the coercive force increases as Sm is added. From Fig. 2, the amount of Sm added is Co-Ni-
It can be seen that when it is 1 to 20 atomic% with respect to Cr, it is effective in increasing the coercive force. Therefore, the amount of Sm added is preferably in the range of 1 to 20 atomic%.

Furthermore, in the present invention, an oxide layer may be formed on the surface of the partial oxide layer of the Fe--Co alloy in order to improve durability. There are many methods for forming the surface oxide layer, but it is preferable because the heat treatment in the atmosphere can be easily and uniformly formed. The thickness of the surface oxide layer depends on the heat treatment temperature and time.However, if the treatment temperature is too high or the treatment time is too long, the surface oxide layer becomes thick and the recording / reproducing spacing is deteriorated. Or the magnetic properties of the partial oxide of the Fe—Co alloy itself deteriorate. Therefore, the treatment temperature is preferably 80 to 200 ° C., and the treatment time is preferably 30 to 600 minutes. By heat-treating under the conditions of this range, the dynamic friction coefficient of the partial oxide layer of the Fe—Co alloy is lowered, scratches are less likely to occur, and durability is significantly improved. According to the analysis by X-ray photoelectron spectroscopy, F was found on the surface of the partial oxide layer of the Fe-Co alloy heat-treated in the above range.
An oxide layer of e and Co is formed and its thickness is 10 to 10.
It is in the range of 300Å.

[0020]

The present invention will be described in more detail based on the following examples, but the invention is not intended to be limited thereto.

Example 1 A Cr film was prepared as a non-magnetic underlayer on a polyimide film having a thickness of 30 μm by a high frequency magnetron sputtering method. As the sputtering machine, a sputtering machine capable of including three 6-inch diameter targets was used, and a Cr target, a Co-Ni-Cr alloy target, and an Fe-Co alloy target were attached. The polyimide film was attached to the substrate holder by applying appropriate tension.

First, a Cr film was sputtered. Ultimate vacuum 2 ×
Argon gas was introduced from the state of 10 ^-6 Torr to 15 mTor
It was r. The substrate temperature was 150 ° C. The substrate temperature was adjusted by flowing oil at 150 ° C. into the substrate holder. Sputtering was performed at a sputtering power of 300 W for 2 minutes and 20 seconds. The film thickness was 1000Å.

Subsequently, a Co—Ni—Cr alloy magnetic film was deposited without breaking the vacuum. The composition is Co62.5 at.%, Ni30a
Using an alloy target containing t.% and Cr at 7.5 at.%, the argon gas pressure was 1.2 mTorr, the substrate temperature was 150 ° C., and the sputtering power was 500 W for 1 minute. Film thickness is 100
It was 0Å.

Further, a Fe-Co partial oxide was deposited while maintaining the vacuum. An Fe-Co alloy target with Co of 60 at.% Was used, and argon gas was introduced to obtain 2.4 mTorr. Further, 7 CCM of oxygen gas was introduced, and the substrate holder was sputtered at a sputter power of 900 W for 30 seconds while cooling with water. The film thickness was 500Å. A disc with a diameter of 2 inches was cut out from the obtained sheet, and the recording / reproducing characteristics were measured with a 2-inch data disk drive and the magnetic characteristics were measured with a sample vibrating magnetometer. For the recording / reproducing characteristics, the reproducing output in each frequency range was monitored by changing the writing frequency. As reference data, the recording / reproducing characteristics of a commercially available coated medium were also measured in the same manner. The results are shown in FIG. 3, Table 1 and Table 2. It can be seen that the medium of the present invention has a larger reproduction output in the entire frequency range than the coated medium.

Comparative Example 1 A medium was prepared in the same manner as in Example 1 except that the Fe—Co partial oxide film was not deposited. The results of recording / reproducing characteristics are shown in Tables 1 and 2.

Examples 2 to 5 A medium was prepared in the same manner as in Example 1 except that the deposition time of the Co—Ni—Cr alloy magnetic film was changed to change the film thickness, and the recording / reproducing characteristics were measured. The results are shown in Tables 1 and 2. Co-Ni
The reproduction output tends to increase as the thickness of the -Cr alloy magnetic film increases, but it is clear that stable rotation cannot be obtained if the thickness is too large.

Examples 6 to 8 A medium was prepared in the same manner as in Example 1 except that the deposition time of the partial oxide film of Fe—Co alloy was changed to change the film thickness, and the recording / reproducing characteristics were measured. The results are shown in Tables 1 and 2. Fe
-A medium without a partial oxide film of a Co alloy, or an extremely thin medium even if provided, has a small output especially at high density,
And it is not durable. On the other hand, if the thickness is too thick, the durability is excellent, but the recording / reproducing characteristics deteriorate.

Examples 9 to 11 A medium was manufactured in the same manner as in Example 1 except that the amount of oxygen introduced during the preparation of the partial oxide film of the Fe-Co alloy was changed to change the saturation magnetization, and the recording / reproducing characteristics were measured. It was measured. The results are shown in Tables 1 and 2. It can be seen that the medium in which the saturation magnetization of the partial oxide film of the Fe-Co alloy is in a certain range has excellent recording / reproducing characteristics.

Example 12 A medium was prepared in the same manner as in Example 1 except that the step of depositing the Cr film was omitted, and the magnetic characteristics and recording / reproducing characteristics were measured.
The results are shown in Tables 1 and 2. It can be seen that when the Cr underlayer does not exist, the in-plane coercive force decreases and the reproduction output level decreases.

Example 13 In the same manner as in Example 1, a Cr film and a Co—Ni—Cr alloy magnetic film were deposited in this order. Subsequently, a Co partial oxide film was deposited. Using Co target, introducing argon gas, 10mTor
It was r. Furthermore, 6.5 CCM of oxygen gas was introduced, and the substrate holder was cooled with water and the DC sputtering power was 900 W.
Sputtered for 5 seconds. The film thickness was 500Å. Magnetic characteristics and recording / reproducing characteristics were measured in the same manner as in Example 1. The results are shown in Tables 1 and 2. It showed stable drivability and excellent regeneration output.

[0031]

[Table 1]

[0032]

[Table 2]

Example 14 A medium was prepared by a high frequency magnetron sputtering method. The target is 6 inch diameter Cr, Co-Ni-Cr, Fe
Using a —Co target, Sm was added by placing an Sm chip on the Co—Ni—Cr target and sputtering. The amount of Sm added was controlled by the number of chips. A polyimide film having a thickness of 30 μm was used as a base film as a substrate material. The film was attached to the substrate holder with appropriate tension. The manufacturing conditions are the ultimate vacuum of about 5 x 1
0 ^-6 Torr, Cr layer, argon gas pressure 15 mTorr, substrate temperature 150 ° C, sputtering power 300 W, film thickness 1000 Å
Met. Subsequently, a Co—Ni—Cr alloy magnetic film containing Sm was deposited without breaking the vacuum. Sm addition is Co-Ni-
^Two 1 cm.sup.2 Sm chips were placed on a Cr alloy target. The composition is (Co-Ni-Cr) -Sm
-Cr is Sm 8 at.%, And Co-Ni-Cr is Co6
It was 2.5 at.%, Ni30 at.%, Cr 7.5 at.%. The argon gas pressure was 1.2 mTorr, the substrate temperature was 150 ° C., the sputtering power was 260 W, and the film thickness was 1500 Å. Further, the Fe-Co partial oxide was deposited while the vacuum was maintained. Co6
A Fe-Co alloy target of 0 at.% Was used, and argon gas was introduced to obtain 2.4 mTorr. Furthermore, oxygen gas 7cc
M was introduced, and the substrate holder was sputtered at a sputter power of 900 W while cooling with water. The film thickness was 500Å. A 2 inch diameter disc was cut out from the obtained sheet,
Recording / reproducing characteristics were measured with a 2-inch data disk drive. Moreover, the magnetic characteristics were measured with a sample vibrating magnetometer. Regarding the recording / reproducing characteristics, the reproduction output at each frequency was monitored by changing the writing frequency. The optimum write current was measured, and the recording / reproducing characteristics were evaluated with the optimum current value. As reference data, the recording / reproducing characteristics of a commercially available coating medium were also measured in the same manner. The results are shown in FIG. 4 and Table 3. It can be seen that the medium of the present invention has a larger reproduction output in the entire frequency range than the coating type medium and the Sm-free Co—Ni—Cr medium (Reference Example 1).

Examples 15 to 18 Under the same conditions as in Example 14, media were prepared by changing only the amount of Sm added to Co-Ni-Cr, and the recording / reproducing characteristics were measured.
The added amounts were 3 at.%, 12 at.% And 20 at.%. The results are shown in Table 3. The coercive force is large in the range of these Sm addition amounts, and the recording / reproducing characteristics are also the coating type medium and the Sm-free Co-Ni
It can be seen that it is superior to the -Cr medium (Reference Example 1).

Reference Example 1 A medium was prepared in the same manner as in Example 14 except that Sm was not added to Co-Ni-Cr. The results of recording / reproducing characteristics and magnetic characteristics are shown in FIG. 4 and Table 3.

Example 19 In Example 14, instead of the Fe--Co target, Co was used.
A target of -CoO (6: 4, atomic ratio) was used, argon gas was introduced to 8 mTorr, and the substrate holder was sputtered at a power of 900 W while cooling with water. The characteristics obtained were as shown in Table 3.

[0037]

[Table 3]

Examples 20 and 21 A polyimide film having a thickness of 30 μm was used as a base film as a substrate material, fixed on the cathode and treated with an argon gas pressure of 3 mTorr and an RF sputtering power of 100 W for 40 minutes. The film was attached to the substrate holder with appropriate tension. Further, a medium was formed thereon by a high frequency magnetron sputtering method. The target used was a Cr, Co-Ni-Cr, Fe-Co target with a diameter of 6 inches, and Sm was added by spattering an Sm chip on the Co-Ni-Cr target. The amount of Sm added was controlled by the number of chips. The manufacturing condition is the ultimate vacuum of about 5 ×
10 ⁻⁶ Torr, Cr layer, argon gas pressure 15 mTorr, substrate temperature 150 ° C., sputtering power 300 W, film thickness 1000
It was Å. Subsequently, a Co—Ni—Cr alloy magnetic film containing Sm was deposited without breaking the vacuum. Sm addition is Co-Ni
^Two 1 cm.sup.2 Sm chips were placed on a --Cr alloy target. The composition is (Co-Ni-Cr) -Sm
Sm8at.% For Ni-Cr, and Co6 for Co-Ni-Cr
It was 2.5 at.%, Ni30 at.%, Cr 7.5 at.%. The argon gas pressure was 1.2 mTorr, the substrate temperature was 150 ° C., the sputtering power was 260 W, and the film thickness was 1500 Å.

Further, a Fe-Co partial oxide was deposited while maintaining a vacuum. An Fe-Co alloy target with Co of 60 at.% Was used, and argon gas was introduced to obtain 2.4 mTorr.
Further, oxygen gas was introduced at 7 ccm, and the substrate holder was sputtered at a sputter power of 900 W while cooling with water. The film thickness was 500Å. A disc with a diameter of 2 inches was cut out from the obtained sheet, and the recording / reproducing characteristics were measured with a 2-inch data disc drive. Moreover, the magnetic characteristics were measured with a sample vibrating magnetometer. Regarding the recording / reproducing characteristics, the reproduction output at each frequency was monitored by changing the writing frequency. The optimum write current was measured, and the recording / reproducing characteristics were evaluated with the optimum current value. As reference data, the recording / reproducing characteristics of a commercially available coating medium were also measured in the same manner. The results are shown in FIG.
Shown in. It can be seen that the medium of the present invention has a larger reproduction output in the entire frequency range than the coating type medium and the medium using the untreated substrate (Reference Example 2).

Examples 22 to 24 Under the same conditions as in Example 21, media were prepared by changing only the sputtering treatment time of the base film, and the recording / reproducing characteristics were measured. The sputtering treatment time was 30 minutes, 50 minutes, and 10 minutes. The results are shown in Table 4. It can be seen that the coercive force is large in any of these sputtering treatment time ranges and the recording / reproducing characteristics are superior to those of the coating type medium and the medium using the untreated substrate (Reference Example 2).

Example 25 In Example 20, Co—C was used instead of the Fe—Co target.
A target of 0 (6: 4, atomic ratio) was used, argon gas was introduced to 8 mTorr, and the substrate holder was sputtered at a power of 900 W while cooling with water. The obtained characteristics are shown in Table 4.

Reference Example 2 A medium was prepared in the same manner as in Example 20 except that the base film was not sputtered. The results of recording / reproducing characteristics and magnetic characteristics are shown in FIG. 5 and Table 4.

[0043]

[Table 4]

Example 26 A polyimide film having a thickness of 30 μm was used as a base film as a substrate material, and was treated for 40 minutes at an argon gas pressure of 3 mTorr and a sputtering power of 100 W. The film was attached to the substrate holder with appropriate tension. Further, a medium was formed thereon by a high frequency magnetron sputtering method. The target has a diameter of 6 inches
Cr, Co-Ni-Cr, Fe-Co targets are used, and Sm addition is Co
It was performed by placing an Sm chip on a -Ni-Cr target and performing sputtering. The manufacturing conditions are the ultimate vacuum of about 5 x 1
0 ^-6 Torr, Cr layer is an argon gas pressure of 15 mTorr, a substrate temperature of 0.99 ° C., sputtering power 300 W, and a film thickness of 1000 Å.

Subsequently, a Co—Ni—Cr alloy magnetic film containing Sm was deposited without breaking the vacuum. Sm addition is Co-
^Two 1 cm.sup.2 Sm chips were placed on a Ni--Cr alloy target. The composition is (Co-Ni-Cr) -Sm
-Ni-Cr with Sm 8 at.%, And with Co-Ni-Cr, Co
It was 62.5 at.%, Ni30 at.%, Cr 7.5 at.%. The argon gas pressure was 1.2 mTorr, the substrate temperature was 150 ° C., the sputtering power was 260 W, and the film thickness was 1750Å. Incidentally, Sm
The addition of Sm does not affect the durability but does not affect the durability, so it is not distinguished whether Sm is added or not.

Further, a partial oxide of Fe--Co alloy was deposited while the vacuum was maintained. An Fe-Co alloy target with Co of 60 at.% Was used, and argon gas was introduced to obtain 2.4 mTorr. Further, oxygen gas was introduced at 7 ccm, and the substrate holder was sputtered at a sputter power of 900 W while cooling with water.
The film thickness was 500Å.

Next, after laminating the thin films in sequence as described above, the laminated sheet was taken out into the atmosphere, and a disc having a diameter of 2 inches was cut out from this laminated sheet and heat-treated in the atmosphere in a drier to obtain a Fe--Co alloy. An oxide layer was formed on the surface of the partial oxide. Heat treatment temperature is 100 ° C, treatment time is 30
It was 0 minutes. After the heat treatment, a liquid lubricant of about 200Å was further applied.

The durability test of the obtained medium was conducted with a 2-inch data disk drive, and when the initial reproduction output was 70% or less, the durability pass number of the medium was defined.
The surface of the medium was observed visually and with an optical microscope. The results are shown in Fig. 6 and Table 5. It can be seen that durability is significantly improved by heat treatment at 100 ° C. for 300 minutes. Also,
No scratches were found on the medium surface even after 10 million passes.

Examples 27 to 29 Under the same conditions as in Example 26, only the heat treatment temperature and time were changed to prepare media, and durability tests and observations were conducted. The results are shown in Table 5. It can be seen that the durability was excellent in all of these heat treatment temperatures and time ranges and that 10 million or more passes were made and no scratches were generated after the passes.

Examples 30 to 32 A medium was manufactured under the same conditions as in Example 26 except for the film thickness of the Co-Ni-Cr alloy layer, and the durability test and observation were conducted. The results are shown in Table 5. Co-Ni-Cr alloy layer thickness of 500Å, 10
It can be seen that the durability and the surface condition after passing are excellent even when changed to 00Å and 3000Å.

Examples 33 and 34 A medium was prepared in the same manner as in Example 26 except that the heat treatment time was changed, and durability tests and observations were conducted. The results are shown in Table 5.

Example 35 Example 2 except that the thickness of the Co—Ni—Cr alloy layer was increased.
A medium was prepared in the same manner as in 6. Table 5 shows the results of the durability test and the observation. When the film thickness of the Co-Ni-Cr alloy layer becomes thick, the medium itself becomes hard, the durability is deteriorated, and the medium surface is scratched. Also, the rotation was defective.

Examples 36 to 38 A medium was prepared in the same manner as in Example 26 except that the heat treatment temperature and time of the medium were changed, and the durability test and observation were performed. The results are shown in Table 5. If the heat treatment temperature is higher than 200 ° C. or if the heat treatment temperature is low and the thickness of the surface oxide layer becomes insufficient, scratches occur on the medium surface.

Examples 39 and 40 A medium was manufactured by the same method as in Example 26 except that the film thickness of the partial oxide layer of the Fe—Co alloy and the film thickness of the Co—Ni—Cr alloy layer were changed, and durability was obtained. A sex test and observation were performed. The results are shown in Table 5. If the thickness of the partial oxide layer of the Fe—Co alloy is increased, the durability deteriorates and scratches occur on the medium surface. Also, the reproduction output is reduced.

Reference Example 3 A medium was prepared in the same manner as in Example 26 except that the medium was not heat-treated. The results of the durability test and the observation are shown in FIG. 6 and Table 5.

[0056]

[Table 5]

[0057]

As mentioned above, the present invention has in-plane anisotropy.
Magnetic film made of Co-Ni-Cr alloy and Fe-
A perpendicular magnetic anisotropy film consisting of a Co alloy or a partial oxide of Co should be used to significantly improve the durability, which is a drawback of conventional metal thin film media, and to optimize the magnetic properties and film thickness of both media. Thus, it is possible to provide a magnetic recording medium having high recording density characteristics and reproduction output. It also has in-plane anisotropy
The coercive force was significantly increased by adding Sm to the magnetic film made of Co-Ni-Cr alloy, and further, the non-magnetic substrate material was sputtered in an argon gas atmosphere so that Co- The coercive force of a magnetic film made of a Ni-Cr or Co-Ni-Cr-Sm alloy can be significantly increased.
Furthermore, by forming an oxide layer on the surface of the perpendicular recording layer made of Fe-Co partial oxide, the durability is greatly improved to 10 million passes or more, and scratches on the medium surface after the pass are eliminated. be able to.

[Brief description of drawings]

FIG. 1 is a diagram showing the relationship between the coercive force in the in-plane direction of a Fe—Co partial oxide / Co—Ni—Cr—Sm / Cr / polyimide film medium and the sputtering time of a polyimide film.

[Fig. 2] Coercive force in the in-plane direction in the Co-Ni-Cr-Sm system
It is a figure which shows the relationship with the Sm addition amount.

FIG. 3 is a graph showing respective recording / reproducing characteristics of a medium of the present invention in which a Co—Ni—Cr alloy magnetic film and a partial oxide film of Fe—Co alloy are laminated and a commercially available 2-inch floppy disk.

FIG. 4 is a diagram comparing the recording density characteristics of a medium with and without Sm added and a commercially available coating medium.

FIG. 5 is a diagram comparing recording density characteristics of a medium obtained by sputtering a polyimide film, a non-treated medium, and a commercially available coating medium.

FIG. 6 shows durability characteristics at a recording signal of 8 MHz in a partial oxide of Fe—Co alloy / Co—Ni—Cr—Sm / Cr / polyimide film medium obtained in Example 26 and Reference Example 3. It is a figure.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (31) Priority claim number Japanese patent application No. 4-22129 (32) Priority date Hei 4 (1992) January 10 (33) Priority claim country Japan (JP)

Claims (10)

[Claims] 1. A Co- having in-plane anisotropy on a non-magnetic substrate.
A magnetic film made of Ni-Cr alloy is provided, and Fe-Co is further formed on it.
A magnetic recording medium provided with a perpendicular magnetic anisotropy film comprising a partial oxide of an alloy or a partial oxide of Co. 2. The magnetic recording medium according to claim 1, wherein a Cr film is provided as a non-magnetic underlayer under the magnetic film made of a Co—Ni—Cr alloy. 3. A Sm of 1 in a magnetic film made of a Co-Ni-Cr alloy.
The magnetic recording medium according to claim 1 or 2, wherein the magnetic recording medium is added in an amount of -20 atom%. 4. The non-magnetic substrate is made of a polyimide film and is sputtered in an Ar atmosphere.
The magnetic recording medium described. 5. The unevenness on the surface of the polyimide film which is sputtered, has a depth of 0.02 to 0.1 micron,
The magnetic recording medium according to claim 1, which has a width of 0.03 to 0.5 micron. 6. The magnetic recording medium according to claim 1, wherein the perpendicular magnetic anisotropy film is made of a partial oxide of Fe—Co and the surface is oxidized by 30 to 300 Å. 7. The saturation magnetization of a perpendicular magnetic anisotropy film made of a partial oxide of Fe—Co alloy or a partial oxide of Co is 300 to 7
The magnetic recording medium according to any one of claims 1 to 6, wherein the magnetic recording medium has a density of 00 emu / cm ³ . 8. A perpendicular magnetic anisotropy film made of a partial oxide of Fe—Co alloy or a partial oxide of Co has a thickness of 300 to 100.
The magnetic recording medium according to claim 1, wherein the magnetic recording medium is 0Å. 9. The magnetic recording medium according to claim 1, wherein the magnetic film made of a Co—Ni—Cr alloy has a thickness of 500 to 4000 Å. 10. A polyimide film having a thickness of 25 to 30 μm, on at least one side of which is a Cr film as a non-magnetic underlayer, a magnetic film made of a Co—Ni—Cr alloy having in-plane anisotropy, and Fe—Co.
A magnetic recording medium for an electronic still camera, comprising a perpendicular magnetic anisotropy film consisting of a partial oxide of an alloy or a partial oxide of Co sequentially formed to have a total film thickness of 2000 to 4000Å.