JPH0581663A - Method and device for producing magnetic recording medium - Google Patents

Abstract

PURPOSE:To continuously produce a magnetic disk ensuring sliding reliability over a long period of time and floating stability of a head and capable of attaining high recording density. CONSTITUTION:A process 1 for forming a magnetic film, etc., on a substrate, a process 2 for sticking fine particles to the surface of a protective film, an etching process 3, a process 4 for removing the particles and a process 5 for applying a lubricant are continuously carried out to continuously produce a magnetic disk with hills of a uniform height and prescribed size formed on the surface of the protective film under prescribed arrangement. Since a stain sticking to the floating surface of a head is effectively removed by the hills, sliding reliability over a long period of time and floating stability of the head are ensured even in a high density magnetic disk device with low flotation of the head.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and an apparatus for manufacturing a magnetic recording medium used in a magnetic disk device.

[0002]

2. Description of the Related Art In recent years, the importance of a magnetic disk device as an external storage device of a computer system has increased, and the recording density thereof has been remarkably improved year by year. As a magnetic disk compatible with such high recording density, a thin film magnetic disk using a magnetic thin film is rapidly increasing in place of a conventional coating type medium in which a magnetic paint prepared by kneading magnetic powder and a binder is applied on a substrate. ..

The general structure of a thin film magnetic disk (hereinafter, simply referred to as a magnetic disk) using such a magnetic thin film is as follows. The substrate is composed of an aluminum alloy disc and a hard underlayer formed on the disc. When a disc material having high hardness such as glass is used instead of the aluminum alloy, the base film may be omitted. A magnetic film is formed on the substrate, and an intermediate film may be formed between the two for the purpose of improving adhesion and improving the characteristics of the magnetic film. A protective film and, if necessary, a lubricating film are formed on the magnetic film to form a magnetic disk.

A magnetic recording device has a magnetic disk, a recording / reproducing magnetic head (hereinafter simply referred to as a head), a magnetic disk rotation control mechanism, a head positioning mechanism, and a recording / reproducing signal processing circuit as main constituent elements. The general recording / reproducing method is that the head and the magnetic disk are in contact with each other before the operation is started, but by rotating the magnetic disk, a minute space is created between the head and the magnetic disk, and recording / reproducing is performed in this state. To do. At the end of the operation, the rotation of the magnetic disk stops and the head and the magnetic disk come into contact with each other again. In order to improve the recording density of the magnetic recording device (contact start / stop system, hereinafter referred to as CSS system), the smaller the flying height of the head during recording / reproduction, the better, and the stability of flying of the head at that time is secured. Therefore, the surface of the magnetic disk is required to be as flat as possible.

By the way, the frictional force generated between the head and the magnetic disk at the time of starting and stopping the apparatus causes wear of both and causes characteristic deterioration. Furthermore, if water or the like is present between the head and the magnetic disk while the magnetic disk is stationary, they will be firmly adsorbed, and if activated in this state, a large force will be generated between the head and the magnetic disk, It may damage the magnetic disk. Such a frictional force and an attractive force tend to increase as the surface of the magnetic disk becomes flatter, which conflicts with the requirement for the flying stability of the head as the recording density increases.

[0006] In order to reduce such frictional force and adsorption force, a method of forming fine irregularities on the surface of the protective film has been conventionally proposed. As one example, JP-A-55-84045 discloses a magnetic disk having a protective film having a surface roughness of 20-50 nm. JP 56-22221 A discloses that
There is disclosed a method of forming a protective film having irregularities by interposing a mesh-shaped shielding plate when forming the protective film by a sputtering method. Japanese Unexamined Patent Publication No. 57-20925 discloses a magnetic disk in which minute protrusions are formed on the surface of a protective film. Japanese Patent Application Laid-Open No. 58-53026 discloses a method of irradiating gas ions on the surface of a magnetic disk having a protective film to form irregularities on the surface of the protective film. JP 62
Japanese Unexamined Patent Publication No. -22241 discloses a method of forming unevenness in a range not exceeding the film thickness of the protective film on the surface of the magnetic disk having the protective film by polishing, wet etching or dry etching.

[0007]

All of the above-mentioned prior arts aim at reducing the frictional force and the attractive force generated between the magnetic disk and the magnetic head, and the magnetic recording disk having a high recording density and a small flying height of the head. In the device, sufficient consideration has not been given to long-term sliding reliability and flying stability of the head, and a method for mass-producing magnetic disks satisfying the requirements has not been disclosed.

An object of the present invention is to provide a manufacturing method and an apparatus for mass production of a magnetic disk capable of sustaining sliding reliability and head flying stability for a long period of time.

[0009]

In order to achieve the above object, the following magnetic disk manufacturing method and apparatus are provided. Provided is a method for manufacturing a magnetic recording medium having at least a magnetic film and a protective film on a substrate, which comprises using at least the following steps, and an apparatus for achieving the method. ..

(A) a film-forming step of laminating at least a magnetic layer and a protective layer on a non-magnetic substrate, (b) a step of dispersing and attaching fine particles to the surface of the substrate manufactured in (a), and (c) (b) A step of physically and / or chemically etching the manufactured substrate, a step of removing fine particles on the surface of the substrate manufactured in (d) and (c), and a lubricant applied to the substrate manufactured in (e) and (d) The process of doing.

According to the present invention, a large number of hills can be formed on the surface of the protective film of the magnetic disk by the above-mentioned series of steps, and long-term sliding is achieved in the high recording density magnetic disk device in which the flying height of the magnetic head is small. It is based on the knowledge that a magnetic disk that can maintain reliability and flying stability of the head can be manufactured continuously and economically.

In the above (a), an ordinary film forming apparatus, for example, a sputtering apparatus can be industrially used.
In (b), as the fine particles, for example, an average particle size of 5 to 1
A magnetic disk in which particles of 0 μm are dispersed in a suitable solvent and the slurry is sprayed through a nozzle with a suitable gas flow if necessary, and static electricity is applied to the fine particles if necessary. Can be attached to a surface. The magnetic disk to which the fine particles are attached is continuously conveyed to the etching step (C), and is physically and / or chemically etched. In the etching step, for example, in plasma of argon or a mixed gas of argon and oxygen,
The surface of the protective film of the magnetic disk is etched by using the fine particles as a mask to form fine irregularities on the surface of the protective film. When a carbon-based protective film (C film formed by sputtering method, diamond-like C film formed by plasma CVD method, etc.) is used as the protective film material, for example, C
It was found that a very active surface is formed on the surface of the protective film. Normally, the etching equipment is in a depressurized state, and when transferring the magnetic disk from this equipment to the equipment of the next step (d),
It needs to be atmospheric pressure. It is preferable to strictly control the composition of the gas that comes into contact with the surface of the magnetic disk at atmospheric pressure. The reason for this is that the surface of the protective film after etching is very active, the surface energy changes depending on the type of gas that comes into contact after etching, and the adhesiveness of the lubricant greatly differs.

The step (d) has a function of removing fine particles adhering to the surface of the magnetic disk, and the fine particles on the surface of the magnetic disk are removed by a high-speed flow of gas or liquid. Further, the step (e) can be used to attach the lubricant.

[0014]

According to the present invention, the step of forming a magnetic film, a protective film, etc. on a substrate, the etching step of forming a large number of hills on the surface of the protective film, and the lubricant application step are continuously carried out on an industrial scale. Therefore, a magnetic disk having a large number of hills formed on the surface of the protective film can be efficiently manufactured on a mass production scale.

Further, according to the present invention, since a polar functional group can be efficiently provided to the surface of the active protective film after etching, the adhesive strength between the lubricant and the surface of the protective film is large, and sliding is prevented. A highly reliable magnetic disk can be efficiently manufactured on a mass production scale.

[0016]

The present invention will be described in detail below.

FIG. 1 shows a manufacturing process of a magnetic disk according to an embodiment of the present invention. As the substrate of the magnetic disk, a hard underlayer film of NiP, alumite, etc. formed on an aluminum alloy disc, a glass, ceramics, hard plastic disc, etc. as it is, or a surface underlayer film of which is formed. preferable. The above-mentioned substrate is subjected to an appropriate pretreatment (if necessary, washing, texture formation, etc., not shown), and then an intermediate film, a magnetic film and a protective film are formed in a film forming process 1 such as a magnetic film. .. The material of the magnetic film is preferably a material having a high saturation magnetic flux density and a high coercive force, and as an example, CoNi
Alloys, CoCr alloys, and alloys containing one or more other metal elements such as Zr, Ta, and Pt added thereto are particularly preferable. It is desirable that the material of the intermediate film be capable of promoting the crystal orientation of the magnetic film. For example, when the magnetic film is a Co-based alloy, Cr and Cr to which one or more other elements are added are particularly preferable. A protective film is formed on the surface of the magnetic film, and many hills are formed on the surface by this method. Here, as the protective film, a C film formed by a sputtering method or a CVD method, SiO ₂ , metal carbide, metal nitride, metal oxide, metal boride or the like is used. From the viewpoint of productivity and sliding durability, a C-based film is particularly desirable. Here, the type of C-based film is a film formed by a sputtering method, such as a film formed by sputtering in argon, a gas in which hydrogen or methane is added to argon, or nitrogen,
The same effect can be expected in the present invention for a film formed by the plasma CVD method (so-called diamond-like C film), a film formed by modifying the surface of the film formed by ion implantation, or the like.

In the particle adhering step 2, fine particles are dispersed and adhered to the surface of the substrate on which the above-mentioned protective film is formed.

In the present invention, the method for dispersing and adhering the solid particles on the surface of the protective film uses a suspension in which the solid particles are dispersed in a suitable liquid, and spin coating, spray coating, or spraying with a gas flow. By the method, fine particles can be dispersed and attached to the surface of the protective film. The liquid used here is preferably one that does not cause evaporation residue, and for example, pure water, a high-purity fluorine-based solvent, an organic solvent, or the like can be used. In the present invention, in the method of attaching solid particles as described above,
By appropriately selecting the density of the solid particles in the suspension and the conditions at the time of attachment, the density of the solid particles attached to the surface of the protective film can be arbitrarily controlled. At that time, the solid particles may be appropriately charged to improve the efficiency of adhesion to the surface of the protective film.

The material of the solid particles used in the present invention must satisfy the following conditions.

1) When the above-mentioned suspension is used to disperse and adhere to the surface of the protective film, there is no dissolution or elution when the solid particles are dispersed in a liquid.

2) Decomposition by the above etching process,
Hard to change.

3) It can be easily removed from the surface of the protective film after etching.

The characteristic 1) is necessary so as to prevent generation of unnecessary residue after evaporation of the liquid. The characteristic of 2) is necessary for preventing decomposition or alteration products of the solid particles from unnecessarily adhering to the surface of the protective film due to etching, since the solid particles act as a masking agent during etching.

As a result of searching various materials satisfying such conditions, the inventors have found that a material containing at least fluorine and carbon or a fluororesin is particularly desirable.
Specific examples are polytetrafluoroethylene, polychlorotrifluoroethylene, copolymers of tetrafluoroethylene and perfluorovinyl ether, fluorinated graphite and the like, and their derivatives. Since these materials are chemically extremely stable and have excellent chemical resistance and plasma resistance, they meet the above conditions 1) and 2). Further, since the above materials have extremely low surface energy, they have a small adhesion to other solid surfaces and can be easily removed by simple washing and the like, so that they meet the above condition 3) and are desirable. However, the present invention is not limited to the solid particle materials described above, and materials other than those described above, with respect to the liquid selected to make the suspension and the etching method selected to form the hills. Alternatively, it may be selected from organic substances and inorganic substances satisfying the conditions 1) and 2) and the condition 3).

The size of the solid particles used in the present invention is
It should be selected according to the size of the hill formed on the surface of the protective film and the etching method. In the case of a directional etching method such as reverse sputtering or ion beam etching, the size of the hill is almost the same as the size of the solid particles, and the size of the hill is almost the same as the range of the desired hill size. Since it is sufficient to use the solid particles mentioned above, it is more desirable because the size of the hill can be easily controlled. When an etching method such as plasma etching or wet etching that does not have a directivity that easily wraps around the back side of the solid particles is used, the size of the solid particles should be determined in consideration of the wraparound of the etching. Must be larger than size. However, according to the results of the investigation by the inventors, when the size of the solid particles becomes small, the particles are easily aggregated with each other, and it becomes difficult to uniformly disperse and adhere to the surface of the protective film, and the solid particles are removed from the surface of the protective film after being adhered to the magnetic disk surface. Therefore, the minimum particle size of the solid particles used here is preferably 0.1 μm or more, more preferably 0.2 μm or more, and further preferably 0.5 μm.
It is larger than m. The upper limit of the size of the solid particles used is defined by the upper limit of the size of the hill to be formed, but the maximum particle size is preferably 30 μm or less. More desirably, the maximum particle size is preferably 25 μm or less. If the particle size is too large, it is easy to handle after being dispersed and adhered to the surface of the protective film by a slight impact, which is not desirable from the viewpoint of easy handling.

The size and spacing of the hills formed on the surface of the protective film can be controlled by the size of the solid particles used as described above and the deposition method. This makes it possible to accurately form the number of hills and the total area ratio per unit area on the surface of the magnetic disk.

Next, in the etching step 3, the surface of the protective film of the substrate to which the fine particles are attached is etched.

The etching method used here can be selected from dry etching such as ion beam etching, reverse sputtering, plasma etching, etc., wet etching using an etching solution, etc., depending on the material of the protective film. Since the etching method here makes the height of the hills formed almost constant, the etching rate of the protective film in the part where solid particles are not attached is uniform so that it is almost constant in the plane of the magnetic disk. It is desirable to select a different etching method. This makes it possible to accurately form a large number of hills having a substantially constant height within the desired range on the surface of the protective film of the magnetic disk.

In the present invention, the solid particles attached to the protective film are used as a masking agent to etch to form a hill, so it is important whether the etching method used has directionality. For example, when a non-directional etching method such as plasma etching or wet etching that does not easily go around the back side of the solid particles is used, the size of the hills formed is smaller than the size of the solid particles.
It is difficult to control the size of the hill formed. On the other hand, when using a directional etching method such as ion beam etching or reverse sputtering, the size of the hill is almost the same as the size of the solid particles, so the size of the hill to be formed is It is more desirable because it can be controlled by the size of the solid particles. When the directional etching method is used, it is desirable that the etching direction be substantially perpendicular to the magnetic disk surface. Ion beam etching is the most preferable in terms of strictness of directionality, but since there is no practical problem if there is some degree of directionality, the reverse sputtering method is more desirable from the viewpoint of mass productivity. When a C protective film is used as the protective film, reverse sputtering in an atmosphere containing oxygen is more desirable. When the hill is formed in this manner, the action of oxygen modifies the extreme surface layer of the C film, and also has the effect of improving the adhesion strength when the lubricating film is formed on the hill.

In the etching method using plasma, it is preferable to use a mixed gas of argon and oxygen or oxygen, but a gas of a molecule containing at least carbon and halogen may be mixed with the above gas. For example, when etching is performed in a gas containing carbon and fluorine, a fluorine group can be introduced into the surface of the protective film, and the surface can be modified to be hydrophobic.

After the above steps, fine particles adhering to the surface of the substrate are removed in the particle removing step 4 of the substrate. An example of a preferable method for removing fine particles adhering to the substrate surface is a method of scattering and removing fine particles on the substrate surface with a high-speed fluid such as gas or liquid. More preferably, a method of scattering and removing fine particles on the substrate surface with a high-speed fluid such as a fluorine-based solvent or pure water can be applied. further,
In the process of transferring the substrate from the etching process 3 to the particle removing process 4, it is preferable that the substrate surface is not inadvertently exposed to the atmosphere. An atmosphere with a controlled composition is preferable.

By passing through this step, when the protective film material is a carbon-based material, polar functional groups can be efficiently increased on the surface thereof. Further, in a more preferable embodiment of the present invention, a method of removing fine particles by a liquid high-speed fluid in which a perfluoropolyether lubricant is dissolved in a fluorine solvent can be applied.

Further, between the particle removing step 4 and the lubricant applying step 5, or before and after the step of removing the contacting protrusion of the magnetic head (not shown, for example, tape cleaning).
May be provided.

If necessary, a lubricant film is formed on the surface of the protective film in the lubricant applying step 5 to form a magnetic disk. A fluorine-based lubricant is desirable for the lubricating film, and a perfluoropolyether-based lubricant is particularly preferable. It is desirable that the film thickness of the lubricant is smaller than the height of the hill formed on the surface of the protective film. When the film thickness of the lubricating film is larger than the height of the hill, the effect of removing dirt from the air bearing surface by the hill becomes difficult to appear.

According to the present invention, a large number of hills are formed on the surface of the protective film for removing dirt adhering to the air bearing surface of the head, so that the substrate surface can be made substantially flat. As a result, the magnetic film formed above is also flattened, so that it is possible to prevent fluctuations in reproduction output due to unevenness of the magnetic film during recording / reproduction, and it is possible to obtain a magnetic disk having excellent recording / reproduction characteristics. However, if necessary, for the purpose of controlling the orientation of the magnetic film on the substrate surface, extremely minute irregularities within a range smaller than the height of the hill formed on the surface of the protective film, for example, minute grooves in the circumferential direction. Steps for forming etc. (not shown)
The present invention also includes those containing.

In the protective film having a hill formed on the surface thereof according to the present invention, it is more preferable that the material is homogeneous in the hill portion and other portions. This is because when a material different from the other portions is present in the hill portion, peeling easily occurs at the interface when sliding with the head, and sliding durability is reduced. However, different two materials may be present in the protective film when two appropriate materials having particularly excellent adhesion are selected. For example, a material that is not etched by a selected etching method when forming the protective film may be formed in the lower layer, and a material that is etched may be formed in the upper layer. By doing this, only the upper protective film is etched by the etching process when forming the hills on the protective film surface, so that the hills with a height corresponding to the upper protective film thickness are uniformly and accurately. Since it is formed, there is an advantage that the height of the hill can be easily controlled.

The effect of removing dirt on the air bearing surface of the head by a large number of hills formed on the surface of the protective film of the magnetic disk of the present invention is a load / unload type magnetic disk provided with a mechanism for separating the head and the magnetic disk when the apparatus is stopped. It is also extremely effective for a magnetic disk for a contact type magnetic disk device in which the head does not substantially float during recording and reproduction.

Also in the case of the load / unload type magnetic disk device, as in the CSS type magnetic disk device, the adhesion of dirt to the air bearing surface of the head causes the long-term floating stability and durability to be impaired. Therefore, by using the magnetic disk of the present invention in which a large number of hills are formed on the protective film surface as described above, it is possible to obtain a magnetic disk device excellent in head flying stability and durability for a long period of time.

In a magnetic disk device of the CSS system and the load / unload system, which uses a head having an air bearing surface and performs recording / reproduction with a head flying height of 0.01 μm or more and 0.15 μm or less, the flying stability of the head is improved. In order to secure the number of hills formed on the surface of the protective film of the magnetic disk is 50 / mm ² or more within the above total area of the air bearing surface 2.
5 × 10 ⁵ pieces / mm ² or less, more preferably 100 pieces / mm ²
It is preferably 1 × 10 ⁵ pieces / mm ² or less, and more preferably 200 pieces / mm ² or more and 5 × 10 ⁴ pieces / mm ² or less. Further, the total area ratio of the hills formed on the surface of the magnetic disk protective film to the total area of the air bearing surface is 0.1% or more 6
0% or less is desirable. It is more preferably 1% or more and 50% or less. More preferably, it is 2% or more and 40% or less. Further, the average value of the intervals between any hill and the other closest hill is preferably smaller than the average value of the width of the air bearing surface of the head, and more preferably 1/2 or less of the average width of the air bearing surface,
More preferably, it is preferably ⅓ or less of the average width of the air bearing surface. If the number of hills or the area ratio is too small, or if the intervals are too wide, fluctuations in the flying height of the head easily occur even if dirt does not adhere to the air bearing surface, which is not desirable.

In the contact type magnetic disk device,
It is most important to prevent damage to the head or magnetic disk due to contact sliding. By using the magnetic disk of the present invention having a large number of hills described above, it is possible to quickly remove dirt adhering to the sliding surface of the head. Therefore, a head generated due to the existence of dirt between the head and the magnetic disk or It is possible to prevent damage to the magnetic disk and obtain a magnetic disk device having excellent long-term sliding reliability. However, in the contact type magnetic disk device, since it is not necessary to consider the flying stability of the head, the height of the hill formed on the surface of the protective film may exceed the above range as necessary,
For example, the upper limit of the height of the hill may be 60 nm. By increasing the height of the hill, it is easy to prevent the magnetic disk from being damaged by abrasion due to sliding, and it is easy to remove the dirt scraped from the sliding surface around the hill. In a contact type magnetic disk device using a head having a sliding surface, in order to ensure the running stability of the head, a hill formed on the protective film surface of the magnetic disk within the total area of the sliding surface. The number is 50 pieces / mm ² or more and 2.5 × 10 ⁵ pieces / mm ² or less, more preferably 100 pieces / m 2.
m ² or more and 1 × 10 ⁵ pieces / mm ² or less, and more preferably 200 pieces / mm ² or more and 5 × 10 ⁴ pieces / mm ² or less. In addition, the ratio of the total area of the hills formed on the surface of the protective film of the magnetic disk to the total area of the sliding surface is 0.
1% or more and 60% or less is desirable. More desirably 1%
It is preferably 50% or more and 50% or less. More preferably, it is 2% or more and 40% or less. Further, the average value of the intervals between any hill and the other closest hill is preferably smaller than the average value of the width of the head sliding surface, more preferably 1/2 or less of the average width of the sliding surface, Desirably 1/3 of the average width of the sliding surface
The following is preferable. If the number or area ratio of the hills is too small or the spacing is too wide, the running stability of the head is likely to be impaired even if dirt does not adhere to the sliding surface, which is not desirable. FIG. 3 shows a schematic configuration of the magnetic disk device of the present invention. The magnetic disk 9 is attached to a spindle motor 16 which is a rotating means. Magnetic head 1
Reference numeral 3 is attached to a voice coil motor 15 and a carriage 14 which are positioning means for the magnetic head 13.

The height, size, spacing and arrangement of many hills formed on the surface of the protective film of the magnetic disk of the present invention can be measured by the following method. The height of the hill is a two-dimensional or three-dimensional stylus type surface roughness meter, a three-dimensional optical surface roughness meter, a scanning tunneling microscope, an atomic force microscope, etc. A surface having a resolution of nanometer order in the height direction. It is measured by using a shape measuring device. The hill size, spacing, number per unit area, and area ratio are measured using a surface shape measuring method that enables three-dimensional measurement. However, since the above method generally has a small measurable area in the horizontal direction, especially when measuring the number and area ratio per unit area, make sure that the total measurement area is about 1 mm ² It is desirable to perform many measurements and obtain the average value. Here, when the material of the protective film has a relatively dark color such as C film, the size, spacing, number per unit area and area ratio of the hills can be measured by a simpler method. That is, in the present invention, since the film thickness of the protective film is different between the hill portion and other portions, in the case of a colored protective film material, the color contrast is different between the hill portion and other portions, for example, an optical microscope. The hill portion can be accurately identified by observation with. In this case, the size of the hills, the interval, the number per unit area, and the area ratio can be easily measured by analyzing the observation result of the optical microscope by image processing or the like.

In the present invention, the method of forming a large number of hills on the surface of the protective film for removing the dirt adhering to the head has been described so far. For example, the above hills are formed on the substrate by the same method as in the present invention. A magnetic film formed on the surface and having a uniform film thickness,
Even with the method of forming the protective film and the like, the shapes appearing on the surface of the magnetic disk are almost the same, and it goes without saying that the effect of removing dirt from the head of the present invention is exhibited.

<Example 1> The particle coating step 2, the etching step 3 and the particle removing step 4 of the present invention shown in FIG.
FIG. 2 shows an example of a schematic configuration of an apparatus when it is carried out on an industrial scale.

The semi-finished magnetic disk that has undergone the film-forming process 1 has a particle coating unit 6 by, for example, a transfer robot.
Be transported to. In this unit, for example, particles of polymer resin containing at least fluorine and carbon (not necessarily spherical, for example, average particle diameter 5 to 10 μm)
After atomizing the suspension of the fluorinated solvent and, if necessary, entraining it in the gas flow, it is sprayed and adsorbed on the disk surface of the semi-finished product from the nozzle part. If necessary, static electricity can be applied to the particles to improve the adsorption efficiency on the disk surface. Furthermore, the fluorine-based solvent can be recovered and reused. The amount of particles adhering to the disk surface can be controlled by the particle spraying time, and the particles can be evenly adhered to both surfaces of the disk by using the nozzles of two systems while rotating the disk. Furthermore, it is easy to intentionally change the particle adhesion concentration within the surface of the disk by controlling the nozzle position. As an example, it is also possible to control and change the particle adhesion concentration on the inner and outer circumferences of the disk, change the hill area, and control the flying height of the magnetic head on the inner and outer circumferences. As described above, it is possible to control the effective flying height of the magnetic head by changing the hill area in the plane of the disk. Therefore, in a magnetic disk device using a so-called rotary actuator, linear actuator, or the like, there is an advantage that the flying height on the inner and outer tracks of the disk can be controlled substantially uniformly.

For example, 25 discs having particles adhered to their surfaces by the particle coating unit 6 are placed in one magazine, and are transported to the preparation chamber 7 of the etching device 8 by the magazine transport conveyor 11.

In the preparation room 7, the exhaust system 12
After being exhausted to a predetermined pressure, it is transported to the etching chamber 8. In the etching chamber 8, for example, each disk is etched in plasma under the following conditions.
In this case, it is preferable that the hub portion that supports the central portion of the disk is on the ground side. The reason for this is that it has the effect of being uniformly etched in the plane of the disk. Further, it is of course possible to use an apparatus in which a plurality of disks are placed in a rack and processed simultaneously. Also in this case, it is preferable that the hub at the center of each disk is on the ground side.

Pressure: 1 Torr Rf output: 400 W Oxygen gas flow rate: 100 sccm The etching conditions need to be appropriately changed depending on the type and material of the protective film of the disk. It was confirmed that about 20 nm was etched in 6 minutes.

After this processing, the disc carrying magazine is carried from the etching chamber 8 to the take-out chamber 9, and after returning to atmospheric pressure, it is carried to the particle removing unit 10 by the magazine carrying conveyor 11. Here, when the take-out chamber 9 is opened to the atmosphere, it is preferable to use an inert gas. Further, during or subsequent to the above-mentioned etching treatment step, for example, by treating the disc in plasma of molecules containing fluorine, a fluorine group is introduced into the protective film surface of the disc to form a protective film surface. Can be stabilized.

In the particle removing unit 10, a method of scattering and removing particles adhering to the disk surface by a high-speed flow of gas or liquid can be applied. Pure water, a fluorinated solvent, or the like can be used as the high-speed flow. It is also possible to add a fluorine-based lubricant to the above high-speed fluid and apply the lubricant to the disk surface at the same time as removing the fine particles.

The disk from which particles have been removed by the particle removing unit 10 can be transported to the next lubricant application step 5 to apply the lubricant to the disk surface, if necessary. Further, after the particle removing unit 10, in order to remove the minute protrusions on the disk surface, for example, a method of lightly polishing the surface with a tape or the like may be used.

Example 2 NiP was formed on the surface of an aluminum alloy disk having an outer diameter of 5.25 inches by electroless plating.
The underlayer film was formed to a thickness of 15 μm, the underlayer film was polished to 10 μm, and the average roughness (R
a) Mirror-finishing was performed so that the roughness was 2 nm or less and the maximum roughness (Rmax) was 5 nm or less. On this substrate, a Cr intermediate film of 100 nm, a CoNi magnetic film of 50 nm, and a CoNi magnetic film of 50 nm were formed by a sputtering method.
A C protective film having a thickness of 30 nm was formed.

The above substrate was processed by the apparatus shown in FIG. Polytetrafluoroethylene (PTF) with an average particle size of 5 μm
E) A suspension was prepared by ultrasonically dispersing particles at a ratio of 1 wt% in a fluorine-based solvent, and the suspension was spray-applied to the surface of the C protective film by a pump and a nozzle to evaporate the solvent and remove PTF.
E particles were dispersed and adhered on the C protective film. As a result of observing the adhered state of the PTFE particles by an optical microscope, the size of the adhered particles is 90% or more of the total number of particles of 1-10 μm, the average value of the particle intervals is about 15 μm, The density was about 2,500 / mm ² , and the total area ratio of the coated portion of the particles was about 5%.

This disk was PT under the conditions shown in Example 1.
After etching the C protective film in a portion without FE particles by 15 nm, the surface was washed with a high-speed flow of pure water to remove the PTFE particles. From the results of surface observation before and after etching, it was confirmed that hills having almost the same size as the adhered particles were formed on the surface of the C protective film. The average value of the hill spacing after etching was about 15 μm, the density of hills per unit area was about 2,500 / mm ² , and the total area ratio of the hills was about 5%. In addition, as a result of measuring the height of the hill with a stylus type surface roughness meter,
It was confirmed that all were about 15 nm.

On the surface of the disk thus obtained, a perfluoropolyether type lubricating film as a lubricating film was applied by about 5 nm to prepare a magnetic disk.

The minimum guaranteed flying height of the head with respect to the magnetic disk manufactured in this example was 0.04 μm or less, and a highly reliable magnetic disk device could be obtained even when the flying height of the head was 0.08 μm. Furthermore, the magnetic disk manufactured in this example was subjected to a CSS test by the apparatus shown in FIG. 3, but no scratches were observed on the disk surface even after 50,000 CSS operations, and long-term sliding reliability was high. It was a thing. The minimum guaranteed flying height of the head after the CSS test was 0.04 μm or less. As a result of observing the air bearing surface of the head, there was no significant change compared to before the test. From these results, the magnetic disk of the present example was able to secure long-term sliding reliability and flying stability of the head due to the effect of preventing dirt from adhering to the head.

Example 3 A magnetic disk was prepared in the same manner as in Example 2 except that a suspension obtained by ultrasonically dispersing PTFE particles similar to those in Example 2 in a fluorine-containing solvent at a ratio of 0.2 wt% was used. did. The size of the hill of the magnetic disk in this embodiment is the same as that of the second embodiment, and the average value of the hill spacing is about 40 μm.
m, the density of hills per unit area was about 500 pieces / mm ² , and the total area ratio of hills was about 1%. Moreover, as a result of measuring the height of the hill with a stylus type surface roughness meter, it was confirmed that all were about 15 nm.

The CSS test result of the magnetic disk of this embodiment, the flying characteristic measurement result of the head, and the contamination observation result of the air bearing surface of the head are excellent as in the case of the second embodiment, and long-term sliding reliability and head are obtained. It was possible to secure the floating stability of the.

Example 4 A magnetic disk was manufactured in the same manner as in Example 2 except that a suspension obtained by ultrasonically dispersing PTFE particles similar to that in Example 2 in a fluorine-containing solvent at a ratio of 4 wt% was used. The size of the hills of the magnetic disk in this example is the same as that of Example 2, the average value of the hill intervals is about 5 μm, the density of hills per unit area is about 10,000 pieces / mm ² , and the total number of hills is The area ratio was about 20%. Moreover, as a result of measuring the height of the hill with a stylus type surface roughness meter, it was confirmed that all were about 15 nm.

The CSS test result of the magnetic disk of this example, the flying characteristic measurement result of the head, and the contamination observation result of the air bearing surface of the head were excellent as in Example 2, and the long-term sliding reliability and the head were obtained. It was possible to secure the floating stability of the.

Example 5 A magnetic disk was manufactured in the same manner as in Example 2 except that as the protective film, a C film having a thickness of 30 nm was formed by a plasma CVD method using a methane-hydrogen mixed gas as a raw material. The size of the hills of the magnetic disk in this embodiment is the same as that of the second embodiment, the average value of the hill intervals is about 15 μm, and the density of hills per unit area is about 2,500 / unit.
The total area ratio of mm ² and hill was about 5%. In addition, as a result of measuring the height of the hill with a stylus type surface roughness meter, both are 15 nm.
It was confirmed that it became.

The CSS test result of the magnetic disk of this example, the flying characteristic measurement result of the head, and the contamination observation result of the air bearing surface of the head were excellent as in the case of Example 2, and the long-term sliding reliability and head were obtained. It was possible to secure the floating stability of the.

<Embodiment 6> As a substrate, the outer diameter was mirror-finished so that the average roughness (Ra) measured with a stylus surface roughness meter was 1.5 nm or less and the maximum roughness (Rmax) was 4 nm or less. A 25-inch glass substrate is used, and a Cr intermediate film of 100 n is formed on this substrate by the sputtering method as in the second embodiment.
m, CoNi magnetic film was formed to 50 nm, and C protective film was formed to 30 nm. As in Example 2, a hill was formed on the surface of the C protective film, and then a lubricating film was formed to produce a magnetic disk.
The size of the hills of the magnetic disk in this embodiment is the same as that of the second embodiment, the average value of the hill intervals is about 15 μm, the density of hills per unit area is about 2,500 / mm ² , and the hills. The total area ratio was about 5%. Further, as a result of measuring the height of the hill with a stylus type surface roughness meter, it was confirmed that all were 15 nm.

The CSS test result of the magnetic disk of the present embodiment, the flying characteristic measurement result of the head, and the contamination observation result of the air bearing surface of the head are excellent as in the case of the second embodiment. It was possible to secure the floating stability.

<Comparative Example 1> As in Example 2, the outer diameter was 5.2.
An NiP undercoat film was formed on the surface of a 5-inch aluminum alloy disc to a thickness of 15 μm by electroless plating, the undercoat film was polished to 10 μm, and the average roughness ( Ra) 2 nm or less, maximum roughness (Rmax)
It was mirror-finished so as to have a thickness of 5 nm or less. On this board,
A Cr intermediate film of 100 nm, a CoNi magnetic film of 50 nm, and a C protective film of 30 nm were formed by sputtering. In this comparative example, a magnetic disk was produced by directly forming a lubricating film without forming a hill on the surface of the C protective film by the process of Example 1.

The minimum guaranteed flying height of the head for the magnetic disk manufactured in this comparative example was 0.04 μm or less, and a magnetic disk device could be obtained even when the flying height of the head was 0.08 μm. However, the magnetic disk manufactured in this comparative example was subjected to a CSS test by the apparatus shown in FIG. 3, and as a result, scratches were generated on the disk surface after 10,000 CSS operations, resulting in poor sliding reliability. It was In addition, another magnetic disk manufactured in the same manner was measured for the minimum guaranteed flying height of the head after 5,000 CSS operations.
It had deteriorated to μm. As a result of observing the air bearing surface of the head, it was found that dirt that had not been seen before the test adhered to the air bearing surface, which deteriorated the flying characteristics. From this result, it was not possible to secure the sliding reliability and the flying stability of the head for a long period in the magnetic disk of this comparative example.

<Comparative Example 2> Outer diameter of 5.2 as in Example 2.
An NiP undercoat film was formed on the surface of a 5-inch aluminum alloy disc to a thickness of 15 μm by electroless plating, the undercoat film was polished to 10 μm, and the average roughness ( Ra) 2 nm or less, maximum roughness (Rma
x) Mirror-finished so as to be 5 nm or less. On this substrate, a Cr intermediate film of 100 nm and CoN was formed by a sputtering method.
An i magnetic film having a thickness of 50 nm and a C protective film having a thickness of 40 nm were formed. In this comparative example, unlike Example 1, while rotating the disc,
A buff containing abrasive grains was pressed against the surface of the C protective film and polishing was performed for about 10 nm to form a groove along the circumferential direction. The surface of the C protective film thus obtained was measured with a stylus surface roughness meter to have an average roughness (Ra) of 5 nm and a maximum roughness (R).
max) 30 nm. A magnetic film was manufactured by forming a lubricating film on the surface of the C protective film.

The minimum guaranteed flying height of the head for the magnetic disk manufactured in this comparative example was 0.09 μm,
The flying stability of the head was poor and it was impossible to apply it to a magnetic disk device with a flying height of 0.08 μm. The magnetic disk manufactured in this comparative example was CS-treated by the apparatus shown in FIG.
As a result of the S test, scratches were generated on the disk surface after 30,000 CSS operations, and sliding reliability was insufficient. Further, with respect to another magnetic disk manufactured in the same manner, the minimum guaranteed flying height of the head after 20,000 CSS operations was measured, and it was further deteriorated to 0.14 μm. As a result of observing the air bearing surface of the head, it was found that stains that were not seen before the test adhered to the air bearing surface, which further deteriorated the flying characteristics. From this result, it was not possible to secure the sliding reliability and the flying stability of the head for a long period in the magnetic disk of this comparative example.

[0069]

According to the present invention, a magnetic disk having a large number of hills on the surface of the protective film of the magnetic disk capable of effectively removing the dirt adhering to the air bearing surface of the head is continuously manufactured on an industrial scale. Can be efficiently manufactured. Further, even when the flying height of the head is small, it is possible to obtain a high reliability, high recording density magnetic disk device and a magnetic disk used therefor, which can secure sliding reliability and flying stability of the head for a long period on a mass production scale. it can.

[Brief description of drawings]

FIG. 1 is a flowchart of a magnetic disk manufacturing process according to an embodiment of the present invention.

FIG. 2 is a block diagram of a part of a magnetic disk manufacturing apparatus according to an embodiment of the present invention.

FIG. 3 is a block diagram showing the configuration of a magnetic disk device according to an embodiment of the present invention.

[Explanation of symbols]

1 ... Film forming step, 2 ... Particle applying step, 3 ... Etching step, 4 ... Particle removing step, 5 ... Lubricant applying step.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Shoichi Sawahata 4026 Kuji-cho, Hitachi City, Ibaraki Prefecture Hitachi Research Laboratory Ltd. (72) Inventor Hiroshi Yaburo 2880 Kunifuzu, Odawara City, Kanagawa Hitachi Ltd. Odawara Corporation In-house (72) Inventor Yoichi Inomata 2880, Kozu, Odawara-shi, Kanagawa Stock Company Hitachi, Ltd. Odawara Plant (72) Inventor Yoshihiro Moriguchi, 2880, Kozu, Odawara, Kanagawa Hitachi Ltd., Odawara Factory

Claims (10)

[Claims] 1. A method of manufacturing a magnetic recording medium including a magnetic film and a protective film on a substrate, comprising the following manufacturing steps. (A) a step of laminating a magnetic layer and a protective layer on a non-magnetic substrate, (b) a step of dispersing and attaching fine particles on the non-magnetic substrate, and (c) a physical and / or chemical step of attaching the non-magnetic substrate. A step of processing by etching, (d) a step of removing fine particles from the surface of the non-magnetic substrate, and (e) a step of applying a lubricant to the surface of the non-magnetic substrate. 2. An apparatus for producing a magnetic recording medium including a magnetic film and a protective film on a substrate, which comprises the following constituent elements. (A) A film forming device for laminating a magnetic layer and a protective layer on a non-magnetic substrate, (b) a device for dispersing and attaching fine particles to the surface of the non-magnetic substrate, and (c) a physical and / or chemical process for the non-magnetic substrate. Device for mechanical etching, (d) a device for removing fine particles on the surface of the non-magnetic substrate, and (e) a device for applying a lubricant to the surface of the non-magnetic substrate. 3. The slurry according to claim 2, wherein the slurry in which the fine particles are dispersed in a solvent is sprayed with a gas fluid, if necessary, and then the fine particles are charged with an electrostatic charge. An apparatus for manufacturing a magnetic recording medium using an apparatus having a function of dispersing and adhering to a substrate surface. 4. The magnetic layer and the protective layer are formed on the surface of the non-magnetic substrate according to claim 2, and the surface of the non-magnetic substrate is formed.
An apparatus for manufacturing a magnetic recording medium using an apparatus having a function of etching a substrate on which fine particles are dispersed and attached in argon or plasma containing argon and oxygen. 5. The non-magnetic substrate according to claim 2, wherein fine particles are dispersed and adhered to the surface of the non-magnetic substrate on which the magnetic layer and the protective layer are formed, and then the non-magnetic substrate is etched. An apparatus for manufacturing a magnetic recording medium using an apparatus having a function of removing fine particles adhering to a surface in a high-speed fluid of gas and / or liquid. 6. An apparatus for producing a magnetic recording medium according to claim 5, wherein a fluorine-based lubricant is entrained in the gas and / or liquid high-speed fluid. 7. The method according to claim 2, wherein a fluorine resin or a material containing at least fluorine and carbon is used as the solid particles, and the slurry of the solid particles and the fluorine solvent is sprayed with a gas fluid if necessary. An apparatus for manufacturing a magnetic recording medium using an apparatus having a mechanism for adsorbing the solvent on a substrate surface, then collecting the solvent, and then circulating the solvent. 8. The magnetic recording medium manufacturing apparatus according to claim 2, wherein the material of the protective film is a material mainly containing carbon. 9. The magnetic recording medium manufacturing apparatus according to claim 2, wherein the nonmagnetic substrate is a substrate made of any one of Al alloy, glass, ceramics, and plastics, or a material containing at least any of the above. 10. The apparatus for manufacturing a magnetic recording medium according to claim 2, wherein the solid particles are made of polytetrafluoroethylene (PTFE) or a derivative thereof.