JPH04241222A - Magnetic disk substrate and magnetic recording medium using the same - Google Patents

Abstract

PURPOSE:To obtain high coercive force and squareness ratio by covering a glass plate with an amorphous alloy film comprising titanium and silicon as a surface layer and providing such a material between the glass and the surface layer that gives a rugged pattern on the surface layer CONSTITUTION:A titanium film 4 is formed on a glass plate 2 as a nonmagnetic supporting body in an Ar atmosphere by sputtering, on which an aluminum rugged-pattern forming material 5 is formed. Then an amorphous alloy film 3 comprising titanium and silicon is formed to 3-50nm thickness to obtain a magnetic disk substrate 1. Then on this substrate 1, there are successively formed a chromium film 11, magnetic film 12, and carbon protective film 13. Then the substrate is taken out from the sputtering device and coated with a lubricant oil to form a lubricating layer 14. Thus, a magnetic recording medium 10 is obtained. The obtd. medium 10 has high coercive force, good coercive force aspect ratio, glide characteristics, recording/reproducing characteristics and S/N.

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 used in a magnetic disk device and a magnetic disk substrate used for manufacturing the magnetic recording medium.

0002

2. Description of the Related Art Glass substrates are attracting attention as substrates for high-density magnetic disks because they have excellent surface smoothness, are hard, have high deformation resistance, and have few surface defects. (For example, JP-A-49-122707, JP-A-52-1
No. 8002)

[0003] Furthermore, it is known that the contact characteristics between the coating film and the glass substrate are improved by forming irregularities on the surface of the glass substrate using a method of spraying minute droplets of a solution of an organometallic compound. . (For example, JP-A-63-160014)

0004

[Problems to be Solved by the Invention] However, when fine droplets of a solution of an organometallic compound are sprayed onto a glass substrate and dried or fired, there is a large amount of moisture adsorbed on the surface, making it difficult to coat the glass substrate. Because the crystallinity of the initial deposited layer of the earth's membrane and magnetic film is poor, the crystallinity of the entire film becomes poor.
There was a problem that the magnetic properties and recording/reproducing properties deteriorated.

[0005] Furthermore, in order to solve the above problem, a non-magnetic film such as titanium is provided on a glass substrate.
Although oxidation of the magnetic film etc. can be suppressed, since the non-magnetic film is a crystalline film, it affects the crystallinity of the underlying film and magnetic film provided on top of it, resulting in the problem that good magnetic properties cannot be obtained. there were.

The present invention has been made to solve the above-mentioned problems. Specifically, when manufacturing a magnetic recording medium by coating a magnetic film or a base film on a substrate before the magnetic film, It is an object of the present invention to provide a substrate for a magnetic disk, which can be coated with a magnetic film having crystallinity with good reproducibility, thereby allowing a magnetic recording medium having good magnetic properties to be obtained with good reproducibility. Furthermore, the present invention provides a magnetic recording medium with good magnetic properties using the above-mentioned magnetic disk substrate.

[Means to solve the problem]

The present invention is a substrate for a magnetic disk in which a non-magnetic support is coated with an amorphous alloy film of titanium and silicon as a film exposed on the surface. The content of silicon in the amorphous alloy film of the present invention is preferably 35 to 65 at.%. If the silicon content is less than 35 atomic % or more than 65 atomic %, the alloy film tends to crystallize, which is not preferable. If the alloy film is crystallized and coated with the surface exposed,
When a magnetic film is coated on top of the magnetic film or a base film is coated on top of the magnetic film, it becomes difficult to align the crystal grain size of the magnetic film and control it with good reproducibility. It becomes difficult to obtain a magnetic recording medium having good magnetic properties and recording/reproducing properties. The silicon content is 4
More preferably, the content is 0 to 60 atomic %.

[0008] Furthermore, the thickness of the amorphous alloy film made of titanium and silicon according to the present invention is preferably 2 nm or more. If the thickness is thinner than 2 nm, the crystallinity of the magnetic film coated thereon or the base film coated prior to the magnetic film cannot be improved, making it difficult to obtain high coercive force and large coercive squareness. It becomes difficult. Further, the thickness is preferably 3 nm or more in order to completely cover the non-magnetic support with the amorphous alloy film, and the thickness is preferably 50 nm or less in order to prevent a decrease in production efficiency and to prevent the film from peeling off due to stress.

Examples of the nonmagnetic support according to the present invention include glass plates, ceramic plates, aluminum plates, and titanium plates. Among these, it is preferable to use a glass plate from the viewpoint of surface flatness, and among the glass plates, it is particularly preferable to use a glass plate having a soda lime composition manufactured by the float method because it is the cheapest to obtain.

Further, in the magnetic disk substrate of the present invention, a metal film can be interposed between the amorphous alloy film made of titanium and silicon and the nonmagnetic support. Such a metal film has a property of trapping oxidizing gas such as oxygen and moisture released from the surface of the non-magnetic support in the metal film without diffusing into the magnetic film, that is, it has a property of occluding the oxidizing gas. A metal film having a gettering effect is preferable, and a film of titanium, chromium, or tungsten is preferable. Among them, titanium film is most preferred. The thickness of these metal films is preferably 2 to 100 nm. If the thickness is less than 2 nm, the amount of gas that can be occluded becomes small, and if it is thicker than 100 nm, stress in the metal film increases, which is not preferable. Further, the thickness is preferably 100 nm or less in order not to reduce productivity when manufacturing the substrate.

In the magnetic disk substrate of the present invention, a low melting point metal is applied in a layered or discontinuous manner prior to coating the amorphous alloy film so as to form irregularities on the surface of the amorphous alloy film. It can be provided in an island shape. Aluminum, silver, etc. can be used as the low melting point metal. The above-described surface unevenness formed in the form of a continuous layer or a discontinuous island can be provided between the nonmagnetic support and the amorphous alloy film provided thereon. Further, when the metal film is provided between the non-magnetic support and the amorphous alloy film, the metal film is provided between the non-magnetic support and the metal film, or between the metal film and the non-magnetic alloy film. A surface unevenness forming material can be provided anywhere between the crystalline alloy film and the crystalline alloy film.

The amorphous alloy film made of titanium and silicon for the magnetic disk substrate of the present invention is obtained by sequentially coating a titanium film and a silicon film on a non-magnetic support by a known sputtering method, vapor deposition method, etc. It can be obtained by heat-treating at least the surface to form an amorphous alloy of titanium and silicon. It can also be obtained by sputtering using a target containing titanium and silicon.

[0013] The metal film interposed between the amorphous alloy film and the nonmagnetic support can be coated by sputtering or vapor deposition using the metal as a target in a reduced pressure atmosphere. can.

Furthermore, the surface unevenness formation material can be provided by using a known sputtering method using a low melting point metal as a target. The degree of unevenness and the size of the islands of the surface unevenness structure can be adjusted by heating the nonmagnetic support when attaching the low melting point metal, and adjusting the heating temperature.

The second aspect of the present invention is to form an amorphous alloy film of titanium and silicon as a first layer on a non-magnetic support, and at least one member from the group consisting of chromium, molybdenum, and tungsten as a second layer. This is a magnetic recording medium in which a film of a selected metal or alloy is sequentially provided, a ternary alloy magnetic film of cobalt-nickel-chromium as a third layer, a protective film as a fourth layer, and a lubricating layer as a fifth layer. .

[0016] The content of silicon in the first layer of an amorphous alloy film made of titanium and silicon is preferably 35 to 65 atomic %. If the silicon content is less than 35 atomic % or more than 65 atomic %, the amorphous alloy film tends to crystallize, which is not preferable. If the amorphous alloy film is crystallized, when a magnetic film is coated on it or a base film is coated and then a magnetic film is coated on it, the crystal grain size of the magnetic film is made uniform and it is reproducible. This cannot be well controlled, making it difficult to obtain good magnetic properties and recording/reproducing properties. It is further preferable for the silicon content to be 40 to 60 atomic % for the above reasons.

Further, the thickness of the amorphous alloy film made of titanium and silicon of the present invention is preferably 2 nm or more. 3 to obtain a completely continuous amorphous alloy film
It is preferably nm or more. On the other hand, it prevents a decline in production efficiency,
And 50n from the top to prevent film peeling due to film stress.
The thickness is preferably less than m.

The second layer film is a metal or alloy film made of at least one member selected from the group of chromium, molybdenum, and tungsten, and is coated on the amorphous alloy film to form crystal grains of the magnetic film. Align the diameter and serve as the base film. In particular, a chromium film is preferably used.

For the third layer magnetic film, a cobalt-nickel alloy, a cobalt-nickel-chromium alloy, a cobalt-nickel-chromium-tantalum alloy, a cobalt-chromium-tantalum alloy, a cobalt-chromium-zirconium alloy can be used. In particular, a cobalt-nickel-chromium alloy magnetic film combined with a chromium film as a base film is preferably used because of its good magnetic properties. The crystal grain size of this alloy magnetic film is 0.2 to 0.6 nm, preferably 0.3 nm.
It can be aligned to ~0.5 nm.

[0020] As the fourth layer of the protective film, commonly used carbon or silicon dioxide is used, and as the fifth layer, perfluorocarbon coated with lubricating oil is used.

A titanium film is provided between the non-magnetic support and the amorphous alloy film, and a surface of the protective film is further provided between the amorphous alloy film and the titanium film. The low melting point metal can be provided in a layered or island shape so as to form unevenness on the surface.

[0022] Aluminum, silver, etc. can be used as the low melting point metal, and in order to form irregularities on the surface of the protective film, the nonmagnetic support is heated when the low melting point metal is coated by sputtering. This can be done by adjusting the temperature of the perilla.

The third aspect of the present invention is to provide an amorphous alloy film containing titanium and silicon as a first layer and an alloy magnetic film containing cobalt and platinum as a second layer on a nonmagnetic support.
This is a magnetic recording medium in which a protective film is provided as a third layer and a lubricant layer is provided as a fourth layer.

The content of silicon in the first layer of the amorphous alloy film made of titanium and silicon is preferably 35 to 65 atomic %, similar to the second layer of the present invention. If the silicon content is less than 35 atomic % or more than 65 atomic %, the amorphous alloy film tends to crystallize, which is not preferable. When the amorphous alloy film is crystallized and a cobalt-platinum-based magnetic film is coated on it,
It is not possible to make the crystal grain size of the cobalt-platinum-based magnetic film uniform and to control it with good reproducibility, making it difficult to obtain good magnetic properties and recording/reproducing properties. It is more preferable that the content of silicon is 40 to 60 atomic %.

Further, the thickness of the amorphous alloy film made of titanium and silicon of the present invention is preferably 2 nm or more. If the thickness is thinner than 2 nm, the base of the alloy film is
Since this has an adverse effect on the crystal growth of the cobalt-platinum magnetic film during coating with the magnetic film, it becomes difficult to obtain good magnetic properties. The thickness is preferably 3 nm or more in order to form a completely continuous film. Further, the thickness is preferably 50 nm or less in order to prevent a decrease in production efficiency and to prevent film peeling due to film stress.

The cobalt-platinum magnetic film provided on the amorphous alloy film of titanium and silicon is as follows:
A magnetic film containing platinum such as a cobalt-platinum alloy, a cobalt-chromium-platinum alloy, and a cobalt-nickel-platinum alloy can be used. These alloy magnetic films can be coated on the amorphous alloy film so as to have good coercive force and coercive squareness ratio.

As the third layer of protective film, a commonly used carbon film or silicon dioxide film is used, and as the fourth layer, perfluorocarbon coated with lubricating oil is used.

A titanium film is provided between the non-magnetic support and the amorphous alloy film, and a surface of the protective film is further provided between the amorphous alloy film and the titanium film. The low melting point metal can be provided in a layered or island shape so as to form unevenness on the surface.

[0029] As the low melting point metal, aluminum, silver, etc. can be used. The formation of irregularities on the surface of the protective film can be carried out by heating the nonmagnetic support on which the low melting point metal is coated by sputtering and adjusting the temperature.

[0030] In the second and third aspects of the present invention, the amorphous alloy film, alloy magnetic film, and protective film provided on the nonmagnetic support are continuously coated by a known sputtering method performed in a reduced pressure atmosphere. be able to.

[0031]

[Operation] When the amorphous alloy film made of titanium and silicon according to the present invention is sequentially coated with a magnetic film or a base film and a magnetic film, the crystal grain sizes of the base film and the magnetic film are made uniform, and the magnetic film is Improve the magnetic properties and recording/reproducing properties of the film.

[0032]

[Examples] The present invention will be explained below with reference to Examples. Figure 1
(a), (b), and (C) are partial cross-sectional views of an embodiment of the magnetic disk substrate 1 of the present invention. In FIG. The glass plate 2 is coated with an amorphous alloy film 3, and in FIG. 1(b), the glass plate 2 is coated with a titanium film 4, and the titanium film 4 is further covered with an amorphous alloy film 3 made of titanium and silicon. is covered. In FIG. 1(c), a titanium film 4 is coated on a glass plate 2, and aluminum 5 forms a discontinuous island-like structure on the titanium film 4 to form irregularities on the surface of the magnetic disk substrate 1. The aluminum 5 is further coated with an amorphous alloy film 3 made of titanium and silicon. Figure 2 (a
), (b), and (C) are partial cross-sectional views of an embodiment of the magnetic recording medium 10 of the present invention. A chromium base film 11 is coated, a cobalt-nickel-chromium alloy magnetic film 12 is coated on the chromium base film 11, and the magnetic film 1
A carbon protective film 13 is coated on the carbon protective film 2, and a perfluoroalkyl lubricating layer 14 is further applied on the carbon protective film 13. The surface of the lubricating layer 14 is uneven.

In FIG. 2(b), a chromium base film 11 is coated on the magnetic disk substrate 1 shown in FIG. 1(a), and a magnetic film of cobalt-nickel-chromium alloy is coated on the chromium base film 11. 12 is coated, a carbon protective film 13 is coated on the magnetic film 12, and a carbon protective film 1 is further coated on the magnetic film 12.
A lubricating layer 14 of perfluoroalkyl is applied on top of 3.

In FIG. 2(c), a magnetic film 12 of cobalt-nickel-platinum alloy is coated on the magnetic disk substrate 1 shown in FIG. 13 is coated with carbon protective film 13.
A perfluoroalkyl lubricating layer 14 is applied thereon.

Example 1 A glass plate having a soda lime composition which had been processed into a disk shape and had been chemically strengthened was thoroughly cleaned and set in an in-line sputtering apparatus, and a film was continuously coated on the glass plate. First, at 200℃ under a pressure of 0.00013Pa (Pascal)
heated to. Thereafter, a titanium target was sputtered in an argon atmosphere of 0.13 Pa, and a titanium film with a thickness of 30 nm was coated on a glass plate heated to 200°C. Next, while heating to 200° C., a concavo-convex structure of aluminum was formed. The conditions for forming the uneven structure are that sputtering is performed using an aluminum target in an argon atmosphere of 0.13 Pa, and the amount of sputtered aluminum is 100 to 20 mm with the glass plate at room temperature.
The amount was set to cover a smooth continuous film with a thickness of 0 nm. Next, a target containing titanium and silicon (50 atom% silicon, 50 atom% titanium) was sputtered in an argon atmosphere of 0.13 Pa to cover an amorphous alloy film of titanium and silicon with a thickness of 20 nm. The glass plate was heated to 300°C. Next, a chromium target was sputtered in an argon atmosphere of 0.13 Pa to coat a chromium film with a thickness of 150 nm. Next, a cobalt-nickel-chromium alloy target was sputtered in an argon atmosphere of 0.13 Pa to coat it with a 60 nm magnetic film. Next, a carbon target was sputtered in an argon atmosphere of 0.13 Pa to coat a carbon protective film with a thickness of 30 nm. Next, the glass plate was taken out from the sputtering apparatus, and perfluoroalkyl lubricating oil was applied onto the carbon protective film to obtain a magnetic recording medium having the film structure shown in FIG. 2(a).

When the coercive force of the obtained magnetic recording medium was measured, it was about 1500 Oe, and the coercive force squareness ratio S* was 0.91, which was a good value. Also, the glide characteristic is 2
The recording and reproducing characteristics are good, with a flying height of 3 microinches or less between the head and the magnetic disk surface, and the S/N value is 30d.
B, D50 (frequency at which the output becomes 1/2 of the value at low frequency) was 60 kFCI (number of magnetization reversals per inch).

Example 2 A glass plate of a soda lime composition processed into a disk shape and chemically strengthened was thoroughly cleaned and set in an in-line sputtering apparatus, and a film was continuously applied onto the glass plate. First, at 200℃ under a pressure of 0.00013Pa (Pascal)
heated to.

Next, a target containing titanium and silicon (silicon 50
30 nm by sputtering titanium (50 atomic %)
The glass plate was coated with an amorphous alloy film made of titanium and silicon having a thickness of 300° C., and then the glass plate was heated to 300°C. Next, a chromium target was sputtered in an argon atmosphere of 0.13 Pa to coat a chromium film with a thickness of 150 nm. Next, the cobalt nickel chromium alloy target is
．． Sputtering was performed in an argon atmosphere of 13 Pa to coat a 60 nm magnetic film. Next, a carbon target was sputtered in an argon atmosphere of 0.13 Pa to coat a carbon protective film with a thickness of 30 nm. Next, the glass plate was taken out from the sputtering apparatus, and perfluoroalkyl lubricating oil was applied onto the carbon protective film to obtain a magnetic recording medium having the film structure shown in FIG. 2(b).

When the coercive force of the obtained magnetic recording medium was measured, it was about 1500 Oe, and the coercive force squareness ratio S* was 0.93, which was a good value. Also, the glide characteristic is 2
The recording and reproducing characteristics are good, with the flying height between the head and the magnetic disk surface being 3 microinches, and the S/N value is 32d.
B, D50 (frequency at which the output becomes 1/2 of the value at low frequency) was 65 kFCI (number of magnetization reversals per inch).

Example 3 A glass plate having a soda lime composition which had been processed into a disk shape and had been chemically strengthened was thoroughly cleaned and set in an in-line sputtering apparatus, and a film was continuously coated on the glass plate. First, at 200℃ under a pressure of 0.00013Pa (Pascal)
heated to. Next, a target containing titanium and silicon (40 atom% silicon, 60 atom% titanium) was sputtered in an argon atmosphere of 0.13 Pa to cover an amorphous alloy film of titanium and silicon with a thickness of 30 nm. The glass plate was heated to 300°C. Next, a cobalt nickel platinum alloy target was sputtered in an argon atmosphere of 0.13 Pa, and a 60 nm magnetic film (platinum 1
(5 at. % nickel, 7 at. % cobalt, 78 at. %). Next, a carbon target was sputtered in an argon atmosphere of 0.13 Pa to coat a carbon protective film with a thickness of 30 nm. Next, the glass plate was taken out from the sputtering apparatus, and perfluoroalkyl lubricating oil was applied onto the carbon protective film to obtain a magnetic recording medium having the film structure shown in FIG. 2(c).

When the coercive force of the obtained magnetic recording medium was measured, it was about 1500 Oe, and the coercive force squareness ratio S* was 0.75, which was a good value. Also, the glide characteristic is 2
The recording and reproducing characteristics are good, with the flying height between the head and the magnetic disk surface being 3 microinches, and the S/N value is 33d.
B, D50 (frequency at which the output becomes 1/2 of the value at low frequency) was 65 kFCI (number of magnetization reversals per inch).

[0042]

Effects of the Invention The magnetic disk substrate of the present invention is coated with an amorphous alloy film made of titanium and silicon so as to be exposed on the surface. Therefore, when manufacturing a magnetic recording medium by coating a magnetic film on the magnetic disk substrate of the present invention, the crystal grain size of the magnetic film can be made uniform, and the grain size can be controlled with good reproducibility. Thus, a magnetic recording medium with improved recording and reproducing characteristics can be obtained.

Further, the magnetic recording medium of the present invention has a large coercive force and a large coercive force squareness ratio, and furthermore, the magnetic recording medium has a large coercive force and a large coercive force squareness ratio, and also has
/N is large.

[Brief explanation of the drawing]

FIG. 1 is a partial cross-sectional view of an embodiment of a magnetic disk substrate of the present invention.

FIG. 2 is a partial cross-sectional view of an embodiment of the magnetic recording medium of the present invention.

[Explanation of symbols]

1 Glass plate 2 Non-magnetic support 3 Amorphous alloy film made of titanium and silicon 4 Titanium film 5 Aluminum uneven structure 11 Chromium film 12 Magnetic film 13 Carbon protective film 14 Lubricating layer

Claims (8)

[Claims] 1. A magnetic disk substrate in which a non-magnetic support is coated with an amorphous alloy film made of titanium and silicon as a film exposed on the surface. 2. The magnetic disk substrate according to claim 1, further comprising a titanium film interposed between the nonmagnetic support and the amorphous alloy film. 3. A low melting point metal is provided in a layered or island form prior to coating the amorphous alloy film so as to form irregularities on the surface of the amorphous alloy film. Substrate for magnetic disks. 4. The magnetic disk substrate according to claim 1, wherein the amorphous alloy film has a thickness of 2 nm or more. 5. The thickness of the amorphous alloy film is 3 to 50 nm.
The magnetic disk substrate according to claim 4, wherein the magnetic disk substrate is m. 6. On a non-magnetic support, a first layer is an amorphous alloy film made of titanium and silicon, and a second layer is a crystal made of at least one selected from the group of chromium, molybdenum, and tungsten. metal or alloy film,
A magnetic recording medium comprising a cobalt-nickel-chromium ternary alloy magnetic film as a third layer, a protective film as a fourth layer, and a lubricating layer as a fifth layer. 7. A titanium film is coated so as to be interposed between the non-magnetic support and the amorphous alloy film, and the protective film is further provided between the amorphous alloy film and the titanium film. 7. The magnetic recording medium according to claim 6, wherein the low melting point metal is provided in a layered or island shape so as to form irregularities on the surface of the film. 8. On a non-magnetic support, an amorphous alloy film made of titanium and silicon as a first layer, a magnetic alloy film containing cobalt and platinum as a second layer, a protective film as a third layer, A magnetic recording medium in which a lubricating layer is sequentially provided as a fourth layer.