JPH04339315A - Magnetic disk and production thereof and magnetic disk device using magnetic disk - Google Patents

Abstract

PURPOSE:To assure the sliding reliability and floating stability of a head over a long period of time by forming the mounds of a uniform height on the surface of the protective film of the magnetic disk and removing the dirts sticking on the floating surface of the head by these mounds. CONSTITUTION:The protective film 5 is formed on the surface of a magnetic film 4 and the many mounds 7 are formed on the surface thereof. A C film, SiO2, metal carbide, metal nitride, metal oxide, etc., are used for the protective film 4. A lubricating film is formed a need on the surface of the protective film 4, by which the magnetic disk is completed. Since the many mounds 7 for removing the dirts sticking on the floating surface of the head are formed on the surface of the protective film 5 in such a case, the substrate may be substantially flat. The magnetic film 4 is made flat as well in this way and, therefore, the magnetic disk which can prevent the fluctuation in the reproduced output by the ruggedness of the magnetic film at the time of the recording and reproducing and has excellent recording and reproducing characteristics is obtd.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetic disk, a method for manufacturing the same, and a magnetic disk device using the magnetic disk, and particularly relates to a high recording density magnetic disk and a large capacity magnetic disk device.

0002

[Prior Art] In recent years, the importance of magnetic disk drives as external storage devices for computer systems has increased.
The recording density is improving markedly year by year. Thin-film magnetic disks using a magnetic thin film are attracting attention as magnetic disks that can support such high recording densities, instead of the conventional coated media in which a magnetic paint mixed with magnetic powder and a binder is coated on a substrate. There is.

[0003] Such a magnetic disk generates frictional force and attraction force between it and a magnetic head mounted on a magnetic disk device. In order to reduce these, it has been conventionally proposed to form microscopic irregularities on the surface of the protective film.

Japanese Unexamined Patent Publication No. 55-84045 discloses a magnetic disk on which a protective film with a surface roughness of 20-50 nm is formed.

Japanese Unexamined Patent Publication No. 56-22221 discloses a method of forming a protective film with irregularities by interposing a mesh-like shielding plate when forming the protective film by sputtering.

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 Unexamined Patent Publication No. 58-53026 discloses a method of forming irregularities on the surface of a protective film by irradiating gas ions onto the surface of a magnetic disk on which a protective film is formed.

[0008] Japanese Patent Laid-Open No. 62-22241 discloses a method of forming irregularities within a range not exceeding the thickness of the protective film on the surface of a magnetic disk on which a protective film is formed by polishing, wet etching, or dry etching. ing.

[0009]

[Problems to be Solved by the Invention] All of the above conventional technologies aim to reduce the frictional force and adsorption force generated between the magnetic disk and the magnetic head, and achieve high recording density with a small flying height of the magnetic head. With regard to magnetic disk drives, no consideration has been given to the long-term sliding reliability of the head and the flying stability of the magnetic head.

An object of the present invention is to provide a magnetic disk device that achieves high recording density with a small flying height of the magnetic head, and which improves the long-term sliding reliability of the head and the flying stability of the magnetic head. The objective is to provide a sustainable magnetic disk device.

[0011]

[Means for Solving the Problems] A magnetic disk used in the magnetic disk device of the present invention has a magnetic film and a protective film on a substrate, and the following (a) to (c) are formed on the surface of the protective film. It is characterized by having a hill.

(a) the height of the hill is approximately uniform;
~40 nm.

(b) There is a distribution in the size of the hills, with 80% or more of the hills having an equivalent diameter of 0.1 to 30 μm.

(c) The above-mentioned hills have a density of 50 to 2.5 per unit area.
×105 pieces/mm2 must exist.

Further, the magnetic disk of the present invention has a magnetic film and a protective film on a substrate, and the protective film has parts with different film thicknesses, and the thick part of the protective film and the thin part of the protective film are different from each other. The thicker portion of the protective film satisfies the following (a) and (b), and is dispersed within the thinner portion of the protective film. shall be.

(a) The thick portion of the protective film has an equivalent diameter of 0.1 to 30 μm, and 80% or more of the protective film has this equivalent diameter.

(b) There are 50 to 5×10 5 thick portions/mm 2 of the protective film per unit area.

Further, the magnetic disk of the present invention has a magnetic film and a protective film on the substrate, and the following (a) is formed on the surface of the protective film.
It is characterized by having a hill comprising ~(c).

(a) The height of the hill is approximately uniform, and
~40 nm.

(b) There is a distribution in the size of the hills, with 80% or more of the hills having an equivalent diameter of 0.1 to 30 μm.

(c) The ratio of the total area of the hills in the area is 0.5 to 60%. Further, the magnetic disk of the present invention is characterized in that it has a magnetic film and a protective film on a substrate, and has a hill having the following (a) to (c) on the surface of the protective film.

(a) The height of the hill is approximately uniform, and
~40 nm.

(b) There is a distribution in the size of the hills, with 80% or more of the hills having an equivalent diameter of 0.1 to 30 μm.

(c) The distance between the hill and an adjacent hill is substantially 1 to 80 μm.

The magnetic disk is a thin-film magnetic disk using a magnetic thin film (hereinafter simply referred to as "magnetic disk").
It is preferable that Generally, a magnetic disk is configured as follows. A magnetic film is formed on a substrate consisting of an aluminum alloy disk and a hard base film formed thereon. If a highly hard material such as glass is used instead of aluminum alloy, the base film may be omitted. An intermediate film may be formed between the substrate and the magnetic film for the purpose of improving adhesion and improving the characteristics of the magnetic film. A protective film is formed on the magnetic film, and a lubricating film is formed on the protective film as necessary.

The magnetic disk of the present invention also includes at least one magnetic disk, a magnetic disk facing the magnetic disk,
A magnetic head for recording and reproducing information (hereinafter simply referred to as a "head"), a rotating means for rotating a magnetic disk, and a head for moving the head to an arbitrary position on the magnetic disk and determining the phase. The main components include a positioning means and a processing circuit for recording and reproducing signals.

[0027] In the recording and reproducing method using this, the head and the magnetic disk are in contact before the start of operation, and by rotating the magnetic disk, a minute space is created between the head and the magnetic disk. Perform recording and playback. At the end of the operation, the magnetic disk stops rotating, and the head and magnetic disk are in contact again. The magnetic disk drive of the present invention uses such a contact start/stop method (hereinafter referred to as "CSS method").

[0028] The present invention provides the following features:
This is based on the investigation of the fact that by forming a large number of hills meeting the above requirements, the sliding reliability of the head and the flying stability of the head can be maintained over a long period of time.

The inventors have investigated various factors that impair long-term sliding reliability and head flying stability in conventional magnetic disk drives, and found that the head flying surface (rail surface or slider It has been discovered that dirt, so-called dust, accumulates on the surface (also known as a surface), and this causes a significant loss of sliding reliability. In other words, dirt adhering to the flying surface of the head reduces stability when the head flies, and the adhering dirt interposes between the head and the magnetic disk, easily damaging both, and causing damage to the magnetic disk drive. This may cause loss of dynamic reliability.

It has been found that the accumulation of dirt on the flying surface of the head becomes more significant as the flying height of the head becomes smaller, especially when the flying height is set to 0.15 μm or less.

The inventors thought that it might be possible to remove dirt on the air bearing surface by forming irregularities on the surface of the magnetic disk, and conducted a detailed study on the surface shape of the magnetic disk and the adhesion of dirt on the air bearing surface. did. As a result, the inventors have discovered that dirt adhering to the air bearing surface can be effectively removed by forming irregularities in a specific shape on the surface of the protective film of the magnetic disk. Removal of dirt on the air bearing surface due to surface irregularities is achieved by scraping off dirt adhering to the air bearing surface by the projections and discharging the scraped dirt around the projections. This is particularly effective when the magnetic disk and head slide in direct contact when the device is started or stopped, or when the flying height is temporarily reduced due to a seek operation, disturbance, etc. even during steady flying. In the present invention, dirt adhering to the air bearing surface can be effectively removed by the many hills formed on the surface of the protective film of the magnetic disk, thereby improving long-term head sliding reliability and head flying stability. Can be sustained.

[0032] The height of the hills formed here is 5 to 40 nm.
and is preferably substantially constant within the hill-forming region of the magnetic disk. The fact that the height of the hill is almost constant means that
This is important for ensuring the initial flying stability of the head, and is particularly important for effectively removing the above-mentioned dirt on the air bearing surface. This is because only the highest hill below the air bearing surface acts primarily to remove dirt.
This is because by making the heights of the hills substantially uniform, more hills can contribute to dirt removal. If the height of the hills is too small, the effect of scraping dirt off the air bearing surface will be reduced, and the volume of the recesses between the hills from which the scraped dirt should be removed will become smaller, which is undesirable. Furthermore, since the present invention is intended for high-density magnetic disk devices with a small flying height of the head, if the height of the hill is too large, the overall thickness of the protective film increases, and the head and magnetic disk during recording/reproduction are This is not desirable because the distance between the magnetic film and the magnetic layer becomes large. To make the removal of dirt on the air bearing surface more effective, the height of the hill should be 10 to 40 nm.
is more desirable. Furthermore, in order to further reduce the distance between the head and the magnetic film, the height of the hill must be 10 to 30 nm.
A range of m is more desirable.

When forming the above-mentioned hills on the surface of the protective film, the protective film has thinner parts and thicker parts, and the thicker parts are dispersed within the thinner parts. The above-mentioned hill may be formed by Here, the thinner and thicker portions each have a substantially uniform thickness, and the difference in thickness between the thicker portion and the thinner portion may be in the range of 5 to 40 nm. desirable. This makes it possible to form hills of uniform height within the range described above.

However, the term "hills" on the surface of the magnetic disk as used in the present invention refers only to those existing on the surface of the protective film with an arbitrary difference in thickness as described above; The microscopic irregularities that occur on the magnetic disk surface due to microstructures such as grain boundaries that occur during the formation of existing magnetic films and intermediate films, etc., and microscopic marks that occur during processing of the underlying film and substrate surface are treated by the present invention. It is not included in the hill.

[0035] It is preferable that the numerous hills formed have a size distribution and are not present at regular intervals. As for the size of these hills, it is desirable that 80% or more of the total number of hills be present in the range of 0.1 to 30 μm, and it is more desirable that no hills of 30 μm or more be present. Since the dirt adhering to the air bearing surface of the head has various shapes and sizes, various dirt can be removed more effectively if the hills have a distribution in size. However, if the size of the hill is too large, it will be difficult for the dirt scraped off the air bearing surface to be removed around the hill, and there is a risk that the dirt that was scraped off will be caught between the magnetic disk and the air bearing surface again. therefore undesirable. If the hill is too small, the dirt on the air bearing surface will simply be swept from side to side.
It becomes difficult to remove from the air bearing surface, and the strength of the hill itself decreases, making it more susceptible to damage when it comes into contact with the head or when dirt is scraped off.

As described above, in order to effectively remove dirt from the air bearing surface, it is desirable that the size of the hills has a distribution within the above range.

[0037] To make the removal of dirt on the air bearing surface more effective,
In addition, in order to further increase the strength of the hills, it is more desirable that 80% or more of the total number of hills have a size of 0.2 to 20 μm, and even more preferably 0.5 to 15 μm.
It is desirable that 80% or more of the total number of μm hills exist. Here, the size of a hill refers to its diameter, for example, if the hill is approximately circular when viewed from directly above, and if it is not circular, it refers to the diameter (equivalent diameter) of an imaginary circle that has the same area as the hill of interest. show. For example, if there is a rectangular hill with a width of 2 μm and a length of 20 μm, its equivalent diameter is approximately 7.1 μm.

It is more desirable that all of the formed hills fall within the above range, but if approximately 80% or more of the formed hills fall within the above range, dirt on the air bearing surface of the head can be effectively effectively removed. Can be removed.

The large number of hills formed here is desirably arranged so that the number per unit area, so-called density, is 50 to 5×10 5 /mm 2 .

[0040] Furthermore, it is desirable to form the hill so that the ratio of the total area of the hills within the unit area to the unit area is 0.5 to 60%. If the number of hills or the total area ratio is too small, there will be parts of the air bearing surface that do not face the hills depending on the position of the head, making it impossible to effectively remove dirt attached to the air bearing surface. On the other hand, if the number of hills and the total area ratio are too large, it will be difficult for the scraped dirt to be removed into the depressions around the hills, and the scraped dirt will be caught between the magnetic disk and the air bearing surface again. Undesirable due to fear.

In order to make the removal of dirt on the air bearing surface more effective, the number of hills per unit area should be 100 to 1×1.
05 pieces/mm2, and even more preferably 200 to 5 x 104 pieces/m2.
It is desirable that they are arranged so that the distance is m2.

[0042] In order to make the removal of dirt on the air bearing surface more effective, it is more desirable to form the hills so that the ratio of the total area of the hills within the area to the unit area is 1 to 50%. , more preferably 2 to 40%.

The large number of hills formed here are so-called randomly distributed so that the distance between pairs of adjacent hills, that is, the distance between any one hill and its nearest neighbor, has a distribution. It is desirable that the plurality of hills be arranged so that the average value of the above-mentioned intervals is 1 to 80 μm. Since dirt can adhere anywhere on the air bearing surface, in order to effectively remove dirt, it is desirable that the hills be randomly distributed so that the intervals between the hills are distributed. As a result, no matter where dirt adheres to the air bearing surface, the many hills act evenly, making it easier to remove the dirt. If the average interval between the hills is too narrow, it will be difficult for the dirt removed from the air bearing surface to be removed into the recesses around the hills, and there is a risk that the removed dirt will be caught between the magnetic disk and the air bearing surface again. It is undesirable because of On the other hand, if the average distance between the hills is too wide, depending on the position of the head, there may be parts of the air bearing surface that do not face the hills, making it impossible to effectively remove dirt adhering to the air bearing surface, resulting in a protective film between the hills. The thinner part may come into contact with the head, and sliding durability is likely to be impaired.

[0044] In order to make the removal of dirt on the air bearing surface more effective and to further improve the sliding durability, it is more desirable that the average value of the distance between the hills is 2 to 60 μm, and even more desirable, It is preferable that the average value of the distance between the hills is 5 to 50 μm. Here, the distance between hills refers to the minimum distance between the outer peripheral portions of two adjacent hills, and does not mean the distance between the centers.

According to the present invention, by forming hills in the above-mentioned range on the surface of the protective film of the magnetic disk, dirt adhering to the flying surface of the head can be effectively removed. Also in a disk device, long-term head sliding durability and head flying stability can be ensured.

Further, according to the present invention, since a large number of hills are formed on the surface of the protective film of the magnetic disk for removing dirt on the air bearing surface, the magnetic layer can be formed flat. This makes it possible to prevent fluctuations in reproduction output due to unevenness of the magnetic film during recording and reproduction, and to obtain a magnetic disk with excellent recording and reproduction characteristics.

It is sufficient that these hills are formed substantially in the area where the head moves on the magnetic disk.

In addition, when forming a lubricant film on the surface of a protective film on which many hills are formed, the lubricant film should be formed with a film thickness that does not exceed the height of the hills, that is, a film thickness that is thinner than the height of the hills. It is preferable to form. This is to prevent the concavities around the hills from being buried by the lubricating film and the dirt removal effect being lost.

Furthermore, it is preferable that the protective film and the hills formed on the surface of the protective film are made of the same material. This is because when hills are formed using different materials, peeling of the hills is likely to occur, and the strength is likely to be insufficient.

Furthermore, the magnetic disk manufacturing method of the present invention has the following features.

A step of forming a magnetic film on a substrate, a step of forming a material to be a protective film on the magnetic film, and a step of dispersing a large number of particles having a size distribution on at least a part of the surface of the material. and etching the material using the particles as a mask so that the magnetic film is not exposed, that is, to a thickness that is thinner than, but not exceeding, the thickness of the material that was initially formed with the material that will become the protective film. , a step of forming a large number of hills of substantially uniform height, and a step of removing the particles and forming a protective film having an uneven surface.

[0052] Here, the particles are preferably solid particles, particularly preferably made of a fluororesin or a material containing at least fluorine and carbon. This is because these materials have excellent durability during etching. Further, the solid particles are preferably made of a material made of polytetrafluoroethylene (PTFE), which is a type of fluororesin, or a derivative thereof. This is because PTFE has particularly good etching resistance.

The material of the protective film and the hills formed on the surface of the protective film is preferably made of a material containing carbon as a main component. This is because it has particularly excellent sliding durability.

It is also preferable that the unevenness formed on the surface has a distribution in size and interval, and is formed at a substantially uniform height.

As the etching method, it is preferable to use so-called anisotropic etching, which has a directionality substantially perpendicular to the surface of the magnetic disk. This is because by doing so, it is possible to form a hill having a size substantially the same as the size of the attached particles with good reproducibility.

A method for dispersing and adhering a large number of solid particles to the surface of the protective film is to spin-coat a suspension in which a large number of solid particles are dispersed in a liquid onto the surface of the protective film, and then evaporate the liquid. It is preferable to make it adhere by. In addition, in a suspension in which a large number of solid particles are dispersed in a liquid,
A large number of solid particles may be dispersed and adhered to the surface of the protective film by immersing a semi-finished magnetic disk on which the magnetic film and the material for the protective film are formed, then pulling it up and evaporating the liquid.

[0057] Furthermore, by spraying a suspension in which a large number of solid particles are dispersed in a liquid onto the surface of the protective film and evaporating the liquid, a large number of the solid particles can be dispersed and adhered to the surface of the protective film. You can.

Furthermore, a large number of solid particles may be transported by gas, and the large number of solid particles may be directly dispersed and adhered to the surface of the protective film. This is because the apparatus and operation of these methods are simple and easy, and the productivity is excellent.

According to the manufacturing method of the present invention, solid particles can be attached to the surface of a protective film formed with a substantially constant thickness by an extremely simple method such as coating or dipping, and the solid particles can be used as a mask to form a protective film. By etching, many hills of uniform height can be formed on the surface of the protective film according to the size and arrangement of the attached particles.

Further, the magnetic disk device of the present invention records and reproduces information by floating a magnetic head above the magnetic disk, and the distance between the magnetic disk and the magnetic head during recording and reproduction is 0.01 to 0.01. 0.15 μm,
The magnetic disk has a substantially uniform height of 5 to 40 nm, and has a height of 100 to 40 nm with respect to the area of the air bearing surface of the magnetic head.
It is characterized by having 5×105 hills.

The contamination of the head air bearing surface described in the present invention becomes particularly noticeable when the spacing is 0.15 μm or less. In addition, in order to achieve the recording density intended by the present invention, it is necessary to
m or less is required. However, if the thickness is less than 0.01 μm, it is substantially difficult to fly the head. The presence of the above number of hills in the area of the air bearing surface is necessary for effectively removing dirt from the air bearing surface of the head and for stably flying the head at the flying height within the above range.

Further, the magnetic disk device of the present invention records and reproduces information by floating a magnetic head above a magnetic disk, and the distance between the magnetic disk and the magnetic head during recording and reproduction is 0.01 to 0. .15 .mu.m, and the magnetic disk is characterized in that it has a substantially uniform height of 5 to 40 nm and has 50 to 2.5.times.10.sup.5 hills/mm.sup.2 per unit area.

Further, the magnetic disk device of the present invention records and reproduces information by floating a magnetic head above the magnetic disk, and the magnetic disk has a substantially uniform height of 5 to 40 nm and an equivalent diameter of 5 nm to 40 nm. It is 0.1 to 30 μm, has 50 to 2.5 x 105 hills/mm2 per unit area, and has a recording density of 100 to 5000 M per square inch.
It is characterized by being a bit.

[0064] Recording density is 100 Mbit/inch2
In the following magnetic disk devices, it is possible to achieve a flying height greater than the above, so contamination of the head flying height does not pose much of a problem. On the other hand, in the case of a protective film with hills formed on the magnetic disk, even if the distance between the head and the magnetic film is the minimum, the recording density will be 5000 Mbit/m because the distance between the head and the magnetic film is the sum of the above-mentioned flying height and the maximum film thickness of the protective film.
I think it will be difficult to do more than inch2.

Further, the magnetic disk device of the present invention records and reproduces information by floating a magnetic head above the magnetic disk, and has a hill on the surface of the magnetic disk for removing dirt attached to the magnetic head. Features.

Furthermore, the magnetic disk device of the present invention includes a magnetic disk having a protective film, a rotating means for rotating the magnetic disk, a magnetic head that faces the magnetic disk during rotation, and a magnetic head that rotates the magnetic disk. a positioning means for positioning the magnetic head by moving it to a desired position on the disk, and having a convex portion on the magnetic disk;
The convex portions have a substantially uniform height of 5 to 40 nm, and 80% or more of the convex portions have an equivalent diameter of 0.1 to 30 μm, and are characterized in that they have a size distribution.

The magnetic disk device of the present invention can satisfy the requirements for devices in which the flying height of the head during recording and reproduction will become smaller and smaller in the future, and the recording density will be improved. Also,
At that time, the flying stability of the head is ensured, and even if the surface of the magnetic disk has irregularities, it has almost the same effect as a flat magnetic disk.

Furthermore, the magnetic disk of the present invention may be used in a contact type magnetic disk device in which a head having a sliding surface and a magnetic disk are operated in contact with each other.

[0069]

[Function] As described above, according to the present invention, by forming a large number of hills having the above characteristics on the surface of the protective film of a magnetic disk, a magnetic disk and a magnetic disk device having the following functions can be obtained. .

According to the present invention, by first making the height of the hill formed substantially constant, the height of the hill is, for example, 0.15 μm.
The flying stability of the head can be ensured even at a small flying height such as below. Second, dirt that adheres to the air bearing surface of the magnetic head due to long-term operation can be effectively removed by the hills of the magnetic disk, making it possible to obtain long-term head sliding durability and head flying stability. can. Third, since the surface of the protective film is uneven, it is possible to prevent fluctuations in the reproduction output due to the unevenness of the magnetic film, and it is possible to obtain excellent recording and reproduction characteristics.

Further, according to the present invention, particles are dispersed and adhered to the surface of a protective film of a magnetic disk, and the protective film is etched using the particles as a mask to an extent that does not exceed the thickness of the protective film, and then the particles are removed. , it is possible to accurately form minute hills of uniform height on the surface of the protective film of the magnetic disk, depending on the adhesion state of the particles. Thereby, a magnetic disk having the above-described effect can be manufactured economically and with good reproducibility.

As described above, according to the present invention, in a magnetic disk device in which the flying height of the magnetic head is small, long-term head sliding durability and head flying stability can be ensured, and excellent recording and reproducing characteristics can be achieved. A magnetic disk and a magnetic disk device that achieves high recording density can be provided.

[0073]

[Embodiment] The substrate of the magnetic disk according to the present invention is an aluminum alloy disk on which a hard base film such as NiP or alumite is formed, or a glass, ceramic, or hard plastic disk itself, or the disk itself. For example, a base film may be formed on the surface of the substrate. A magnetic film (layer) 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. The magnetic film is preferably made of a material with high saturation magnetic flux density and coercive force. Preferred examples of such materials include CoNi alloy, CoCr alloy, and Zr and T.
At least one other metal element such as a, Pt, etc. is added. The material for the intermediate film is preferably one that can promote the crystal orientation of the magnetic film. For example, if the magnetic film is made of the above-mentioned Co-based alloy, Cr and a material in which at least one other element is added to Cr are preferred. Particularly preferred. A protective film is formed on the surface of the magnetic film, and a large number of hills are formed on the surface by the method described above. As the protective film, a C film formed by sputtering or CVD, SiO2, metal carbide, metal nitride, metal oxide, or the like is used. From the viewpoint of productivity and sliding durability, C film is particularly desirable. A lubricating film is formed on the surface of the protective film as required, and the magnetic disk is completed. As the lubricating film, a fluorine-based lubricant is preferable, and a perfluoropolyether-based lubricant is particularly preferable. The film thickness of the lubricant is desirably smaller than the height of the hills formed on the surface of the protective film. When the thickness of the lubricating film is greater than the height of the hills, the effect of removing dirt from the air bearing surface due to the hills is less likely to appear.

In the magnetic disk of the present invention, a large number of hills are formed on the surface of the protective film to remove dirt adhering to the air bearing surface of the head, so the substrate surface may be substantially flat. As a result, the magnetic film formed on the substrate also becomes flat, making it possible to prevent fluctuations in the reproduction output due to unevenness of the magnetic film during recording and reproduction, making it possible to obtain a magnetic disk with excellent recording and reproduction characteristics. . however,
If necessary, extremely minute irregularities, such as minute grooves in the circumferential direction, are formed on the substrate surface in an area smaller than the height of the hills on the surface of the protective film, in order to control the orientation of the magnetic film. The present invention also includes a magnetic disk having a magnetic disk.

Next, a specific method of manufacturing a magnetic disk according to the present invention will be described. The inventors conducted various studies on a practical and economical method for manufacturing magnetic disks in order to form the above-mentioned hills on the surface of the protective film, and as a result, they discovered that a large number of solid particles were dispersed on the surface of the protective film of the magnetic disk. By using the solid particles as a mask, etching the protective film to a depth that does not exceed the film thickness, and then removing the solid particles, a large number of particles are formed on the surface of the protective film of the magnetic disk. It has been found that a desired magnetic disk can be obtained by a method of forming minute hills.

An example of a method for manufacturing a magnetic disk according to the present invention is shown in FIG. The etching method used here can be selected from ion beam etching, reverse sputtering, dry etching such as plasma etching, wet etching using an etching solution, etc. depending on the material of the protective film 5. As for the etching method, in order to make the height of the formed hills almost constant, the etching rate of the protective film in the area where the solid particles 8 are not attached is uniform so that it is almost constant within the surface area of the magnetic disk. It is desirable to select a suitable etching method. Thereby, a large number of hills 7 having a substantially constant height within the desired numerical range described above can be formed with high precision on the surface of the protective film 5 of the magnetic disk.

In the present invention, as shown in FIG.
Since the hills 7 are formed by etching the solid particles 8 attached thereon as a masking agent, it is important whether the etching method used has directionality. For example, when using a non-directional etching method such as plasma etching or wet etching, which tends to wrap around the back side of the solid particles, the size of the formed hills 7 will be smaller than the solid particles 8.
, it is difficult to control the size of the formed hill 7. On the other hand, when a directional etching method such as ion beam etching or reverse sputtering is used, the size of the hills 7 is almost the same as the size of the solid particles 8. This is more desirable because the size can be controlled by the size of the solid particles 8 to which it is attached. When using a directional etching method, it is desirable that the etching direction be approximately perpendicular to the magnetic disk surface. Ion beam etching is most desirable from the viewpoint of exactness of directionality, but since there is no practical problem as long as there is a certain degree of directionality, reverse sputtering is more desirable from the viewpoint of mass production. When a C protective film is used as the protective film, reverse sputtering in an oxygen-containing atmosphere is more desirable. When the hills 7 are formed in this way, the extreme surface layer of the C film is modified by the action of oxygen, which also has the effect of improving the adhesion strength when forming a lubricating film thereon.

In the present invention, as a method for dispersing and adhering the solid particles 8 to the surface of the protective film, a suspension 10 in which the solid particles 8 are dispersed in a suitable liquid is prepared using the apparatus shown in FIG. 4 (pump 1
The most practical method is to evaporate the liquid after depositing it on the surface of the protective film 5 of the magnetic disk 9 by spin coating, spray coating, or dipping as shown in FIG. It is true. The liquid used here is preferably one that does not leave any evaporation residue, and for example, pure water, high purity fluorinated solvents, organic solvents, etc. can be used. In the present invention, in the above method for attaching solid particles, the density of the solid particles attached to the surface of the protective film can be arbitrarily controlled by appropriately selecting the density of the solid particles in the suspension and the conditions during attachment. The desired adhesion density as described above can be easily achieved. However, other than the above method, for example, solid particles may be transported by gas and directly dispersed and attached to the surface of the protective film of the magnetic disk. At this time, the solid particles may be appropriately charged to increase the efficiency of adhesion to the surface of the protective film. Alternatively, a solution containing dissolved particulate material may be sprayed onto the surface of the protective film of the disk, and then the solvent may be evaporated. This also forms a mask of solid particles on the surface of the protective film.

The material of the solid particles 8 used in the above embodiments of the present invention must have characteristics that satisfy the following conditions.

1) When the above-mentioned suspension is used to disperse and adhere to the surface of the protective film 5, there should be no dissolution or elution when the solid particles are dispersed in the liquid.

2) Decomposition by the above etching process,
Not easily altered.

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

Characteristic (1) is necessary in order not to produce unnecessary residues after evaporation of the liquid. Characteristic (2) is necessary because the solid particles 8 act as a masking agent during etching and to prevent decomposition or alteration products of the solid particles 8 from adhering to the surface of the protective film during etching. . If the above-mentioned evaporation residue and decomposition and deterioration products remain on the protective film, they cause increased contamination of the air bearing surface of the head. Characteristic (3) is particularly important because if the solid particles 8 ultimately remain on the surface of the protective film, the flying stability of the head will be impaired.

As a result of searching for various materials that meet these conditions, the inventors found that materials containing at least fluorine and carbon or fluorine resins are particularly desirable. Specifically, polytetrafluoroethylene, polychlorotrifluoroethylene, copolymers of tetrafluoroethylene and perfluorovinyl ether, fluorinated graphite, and derivatives thereof are particularly suitable. These materials are chemically extremely stable and have excellent chemical and plasma resistance, so they meet the requirements of (1) and (1) above.
2) conditions are met. Furthermore, since the above-mentioned materials have extremely low surface energy, their adhesion to other solid surfaces is small and they can be easily removed by simple cleaning, etc., so they meet the condition (3) above and are desirable. . However, the present invention is not limited to the solid particulate materials described above, but may also be applied to materials other than those described above, depending on the liquid selected to create the suspension and the etching method selected to form the hills. , may be selected from organic substances and inorganic substances that satisfy the conditions (1) and (2) above, and satisfy the condition (3) above.

The size of the solid particles 8 used in the present invention must be selected depending on the etching method so that the size of the hills 7 formed on the surface of the protective film falls within the above-mentioned range. In the case of a directional etching method such as the above-mentioned reverse sputtering or ion beam etching, the size of the hills 7 is almost the same as the size of the solid particles 8, so the range of the desired size of the hills 7 is determined. Since it is sufficient to use solid particles 8 having approximately the same size range, it is easier to control the size of the hills 7, which is more desirable. When using a non-directional etching method such as plasma etching or wet etching, where the etching tends to wrap around the back side of the solid particles 8, the size of the solid particles 8 should be adjusted in consideration of the etching wrapping. It needs to be larger than 7. However, according to the study results of the inventors, as the size of the solid particles 8 becomes smaller, the particles tend to aggregate together, making it difficult to uniformly disperse and adhere to the surface of the protective film 5.
Since it becomes difficult to remove from the surface, 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 even more preferably 0.5 μm.
It is desirable that the size is larger than that. The upper limit of the size of the solid particles 8 used is defined by the upper limit of the size of the hills 7 to be formed, but the maximum particle size is preferably 30 μm or less. More desirably, the maximum particle size is 25 μm or less. If the particle size is too large, the particles 8 will easily fall off due to a slight impact after being dispersed and adhered to the surface of the protective film 5, which is undesirable from the viewpoint of ease of handling. Although FIG. 3 shows an example in which spherical solid particles 8 are used, it goes without saying that the present invention is not limited to the use of spherical particles.

As described above, the size and spacing of the hills 7 formed on the surface of the protective film 5 can be controlled by the size of the solid particles 8 used and the method of attachment. Thereby, the number of hills per unit area of the magnetic disk surface and the total area ratio of the hills 7 within the area to the unit area can be formed with high accuracy within the desired ranges described above.

[0087] Regarding the protective film 5 having the hills 7 formed on its surface by the method of the present invention, it is desirable that the material be homogeneous in the hill portions and other portions. This is because if the hill 7 part of the protective film is made of a different material from the other parts, peeling is likely to occur at the interface when the protective film 5 slides relative to the head, reducing sliding durability. be. However, if two appropriate materials with particularly excellent adhesion are selected, different materials may be present in the protective film 5. For example, when forming the protective film 5, a material that is not etched by a selected etching method may be formed as a lower layer, and a material that is etched may be formed as an upper layer. In this way, only the upper layer of the protective film is etched by the etching process when forming the above-mentioned hills on the surface of the protective film 5, so that the hills of the height corresponding to the thickness of the upper layer of the protective film are formed uniformly and accurately. It has the advantage that the height of the hill can be easily controlled because it is well formed.

The present invention has so far been described with the main subject being a magnetic disk device using the CSS method, but the effect of removing dirt on the air bearing surface of the head due to the large number of hills 7 formed on the surface of the protective film of the above-mentioned magnetic disk of the present invention. This is extremely effective for load/unload type magnetic disk drives that are provided with a mechanism for separating the head from the magnetic disk when the device is stopped, and for contact type magnetic disks in which the head does not substantially fly during recording and reproduction.

In the case of a load/unload type magnetic disk drive, as in the case of a CSS type magnetic disk drive, the adhesion of dirt to the air bearing surface of the head can impair long-term flying stability and durability. By using the magnetic disk of the present invention in which a large number of hills 7 as described above are formed on the surface of the protective film 5, a magnetic disk device with excellent long-term flying stability and durability of the head can be obtained. Obtainable.

[0090] In CSS type and load/unload type magnetic disk drives that use a head with an air bearing surface and perform recording and reproduction at a head flying height of 0.01 μm or more and 0.15 μm or less, the flying stability of the head is evaluated. In order to ensure this, the number of hills formed on the surface of the protective film 5 of the magnetic disk must be 50/mm2 within the total area of the air bearing surface of the head.
2.5×105 pieces/mm2 or less, more preferably 100 pieces/mm2 or more and 1×105 pieces/mm2 or less, still more preferably 200 pieces/mm2 or more and 5×104 pieces/m2
It is preferable that it is less than m2. Further, the ratio of the total area of the hills formed within the same area of the air bearing surface on the surface of the protective film of the magnetic disk to the total area of the air bearing surface is 0.
It is desirable that it be 5% or more and 60% or less. More preferably 1%
It is preferably 50% or less. More preferably, it is 2% or more and 40% or less. Further, the average value of the distance between adjacent pairs of hills is preferably smaller than the average value of the width of the head air bearing surface, more preferably 1/2 or less of the average width of the air bearing surface, and still more preferably the average value of the air bearing surface width. It is preferable that it is 1/3 or less of the width. If the number or area ratio of the hills is too small or if the interval is too wide, this is undesirable because fluctuations in the flying height of the head are likely to occur even if no dirt adheres to the flying surface.

In a contact type magnetic disk drive, 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 in which a large number of hills are formed as described above, it is possible to quickly remove dirt adhering to the sliding surface of the head. It is possible to obtain a magnetic disk device that can prevent damage to the magnetic disk and has excellent long-term sliding reliability. However, in a contact type magnetic disk drive, there is no need to consider the flying stability of the head, so the height of the hill formed on the surface of the protective film may exceed the above range if necessary. The upper limit of the height may be set to 60 nm. By increasing the height of the hills, it becomes easier to prevent damage to the magnetic disk due to abrasion caused by sliding, and it is also easier to remove dirt scraped from the sliding surface around the hills. In a contact-type magnetic disk drive using a head with a sliding surface, in order to ensure running stability of the head, it is necessary to reduce the amount of hills formed on the surface of the protective film of the magnetic disk within the total area of the sliding surface. The number of pieces is 50 pieces/mm2 or more and 2.5×105 pieces/mm2 or less, more preferably 100 pieces/mm2 or more and 1×105 pieces/mm2 or less, and even more preferably 200 pieces/mm2 or more and 5×104
The number of particles/mm2 or less is preferable. Further, 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 preferably 0.5% or more and 60% or less. More preferably, it is 1% or more and 50% or less. More preferably, it is 2% or more and 40% or less. Further, the average value of the distance between adjacent pairs of hills 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, and even more preferably It is preferable that the width is 1/3 or less of the average width of the surface. If the number or area ratio of the hills is too small or if the interval is too wide, it is undesirable because the running stability of the head is likely to be impaired even if dirt does not adhere to the sliding surface.

FIG. 6 shows a schematic configuration of a magnetic disk device according to the present invention. The magnetic disk 9 is attached to a spindle motor 16 which is a rotating means. The magnetic head 13 has a voice coil motor 15 which is a positioning means for the magnetic head 13.
and attached to the carriage 14.

In order to confirm the effects of the present invention, the adhesion of dirt to the air bearing surface of the head due to long-term operation of the magnetic disk device was evaluated in an accelerated manner using the following method. Figure 7 shows an outline of the evaluation device. The magnetic disk 9 under test was set on a spindle motor 16, and the head 13 was set on a carriage 14 connected to a voice coil motor 15, thereby constructing a CSS type magnetic disk device. 0.1μm magnetic disk device
After placing the filter 18 in the case 17,
Expose to normal atmospheric environment and pass through filter 18.
Atmospheric dust of 1 μm or less was introduced into case 17. Under these conditions, the magnetic disk 9 is rotated at 3600 rpm,
The head 13 was operated for 100 hours while seeking between the innermost periphery and the outermost periphery at 10 second intervals, and after the test, the air bearing surface of the head 13 was observed to relatively evaluate the amount of dirt attached. The area of the air bearing surface of the head 13 is approximately 2 mm2, and the flying height of the head 13 during steady rotation is 0.08 .mu.m at the innermost circumference.

FIG. 8 shows the effect of removing dirt 19 on the air bearing surface of the head 13 due to the large number of hills 7 formed on the surface of the magnetic disk 9 in the magnetic disk device of the present invention.

In the present invention, the flying height of the head 13 was measured by the following method.

After setting the glass disk 9 for flying height measurement and head 13 in a magnetic disk device similar to that shown in FIG. 6, rotate the glass disk 9, observe the flying surface of the head 13 from the back side of the glass disk 9, and observe the The flying height of the head 13 was actually measured by interferometry. The flying characteristics of the test head 13 were determined using the actual measurement results and simulation.

The flying height of the head 13 on the magnetic disk referred to in the present invention is calculated from the above-determined flying characteristics of the head 13 and the rotational speed of the magnetic disk 9 used.

Furthermore, the minimum guaranteed flying height as used in the present invention refers to the lowest flying height at which contact between the magnetic disk 9 and the head 13 is not detected.

The height, size, spacing, and arrangement of the many hills 7 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 hill 7 can be measured using 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. that can achieve nanometer-order resolution in the height direction. It can be measured by using a surface profile measuring device having a. The size, interval, number per unit area, and area ratio of the hills 7 can be measured using one of the above-mentioned surface shape measurement methods that is capable of three-dimensional measurement. However, since the measurable area in the horizontal direction is generally small with the above method, the total measurement area is approximately 1 mm, especially when measuring the number of pieces per unit area and area ratio.
2, it is desirable to perform a large number of measurements near the same location and obtain the average value. Here, when the material of the protective film 5 has a relatively dark color such as C, it is possible to measure the size, interval, number per unit area, and area ratio of the hills 7 using a simpler method. can. That is, in the present invention, since the thickness of the protective film 5 is different between the hill 7 and other parts, in the case of a colored protective film material,
The color contrast differs between the hill 7 and other parts, and the hill 7 can be accurately identified by observation using an optical microscope, for example. In this case, by analyzing the optical microscope observation results by image processing or the like, it is possible to easily measure the size, interval, number of hills per unit area, and area ratio of the hills. FIG. 2 schematically shows an example of the arrangement of hills when the magnetic disk of the present invention is observed with an optical microscope. In the above, a case has been described in which a large number of hills 7 are formed on the surface of the protective film 5 to remove dirt adhering to the head. It is also possible to form a magnetic film, a protective film, etc. of uniform thickness thereon. Even in this case, since the concave and convex shapes appearing on the surface of the magnetic disk are almost the same, it goes without saying that the head dirt removal effect according to the present invention can be obtained. However, in this case, since the magnetic film does not become flat, the above-mentioned effect of preventing reproduction output fluctuations caused by the unevenness of the magnetic film cannot be obtained.

[0100] More specific embodiments of the present invention will be described in detail below.

<Embodiment 1> Referring to FIG. 1, the outer diameter is 5.
A NiP base film 2 is formed to a thickness of 15 μm on the surface of a 25-inch aluminum alloy disc 1 by electroless plating, and then the base film 2 is polished to a thickness of 10 μm and then touched. Average roughness (R
a) A substrate was prepared by mirror polishing so that the roughness was 2 nm or less and the maximum roughness (Rmax) was 5 nm or less. On this board,
A Cr intermediate film 3 of 100 nm thickness and CoN was formed by sputtering.
The magnetic film 4 of I was formed to have a thickness of 50 nm, and the protective film 5 of C was formed to a thickness of 30 nm. Hill 7 was formed on the surface of protective film 5 of C by the following method.

A method for forming hills 7 on the surface of protective film 5 will be explained with reference to FIGS. 3 and 4. A suspension 10 is prepared by ultrasonically dispersing polytetrafluoroethylene (PTFE) particles 8 having an average particle size of 5 μm in a fluorinated solvent at a ratio of 1 wt%, and this suspension 10 is applied to the surface of the protective film 5 of C. was spin-coated using the pump 12 and nozzle 11, and then the solvent was evaporated to deposit the PTFE particles 8 on the surface of the protective film 5 in a dispersed manner. As a result of observing the adhering state of the PTFE particles 8 using an optical microscope, it was found that the size of the adhering particles 8 was 1 to 10 μm in more than 90% of the total number, and the average value of the distance between pairs of adjacent particles 8 was The particle diameter was approximately 15 μm, the number of adhered particles 8 per unit area was approximately 2,500 pieces/mm 2 , and the ratio of the total area covered by the adhered particles 8 to the unit area was approximately 5%.

Next, this disk was reverse sputtered in an Ar atmosphere containing 10% oxygen using a sputtering device to form P.
The portion of the protective film 5 without the TFE particles 8 was etched to a depth of 15 nm. Thereafter, the surface was scrubbed with pure water to remove the PTFE particles 8. From the surface observation results before and after etching, it was confirmed that hills 7 of approximately the same size as the attached particles 8 were formed on the surface of the protective film 5. The average value of the distance between adjacent pairs of hills 7 after etching is about 15 μm, the number of hills 7 per unit area is about 2500/mm2, and the number of hills 7 relative to the area of the region in which the hills 7 are formed is about 2,500 pieces/mm2. The ratio of the total area was about 5%. In addition, as a result of measuring the height of hill 7 with a stylus type surface roughness meter, it was found that the height of hill 7 was approximately 1
It was confirmed that the thickness was 5 nm.

A magnetic disk 9 shown in FIG. 1 was completed by applying a perfluoropolyether lubricant film 6 to a thickness of about 5 nm on the surface of the thus obtained disk.

The minimum guaranteed flying height of the head 13 (see FIG. 6) for the magnetic disk 9 manufactured in this example is 0.
0.04 μm or less, and the flying height of the head 13 is 0.08 μm.
We were able to obtain a highly reliable magnetic disk drive even with m. Furthermore, the magnetic disk 9 manufactured in this example was subjected to a CSS test using the apparatus shown in FIG.
No scratches were observed on the disk surface even after 0 CSS operations.
It was confirmed that the product has high long-term sliding reliability. Further, the minimum guaranteed flying height of the head 13 after the CSS test was still 0.04 μm or less, and as a result of observing the flying surface of the head 13, there was no significant change compared to before the test. From this result, the magnetic disk 9 of this embodiment has a head 13.
It has been found that this has the effect of preventing dirt from adhering to surfaces, ensuring long-term sliding reliability and flying stability of the head.

<Example 2> A magnetic disk was prepared in the same manner as in Example 1, except that a suspension 10 obtained by ultrasonically dispersing PTFE particles 8 in a fluorinated solvent at a ratio of 0.2 wt% was used. 9 was produced. The size of the hills 7 of the magnetic disk 9 in this example is the same as in Example 1, the average value of the distance between adjacent pairs of hills 7 is about 40 μm, and the number of hills 7 per unit area is about 500 pieces/unit area. mm2, and the total area ratio of hills 7 was about 1%. Further, as a result of measuring the height of the hill 7 using a stylus type surface roughness meter, it was confirmed that the height of each hill was about 15 nm.

As a result of conducting a CSS test on the magnetic disk 9 of this example, both the results of measuring the flying characteristics of the head and the results of observing dirt on the air bearing surface of the head were as excellent as those of Example 1, and the results showed that the magnetic disk 9 could last for a long time. It was found that sliding reliability and head flying stability were ensured.

<Example 3> A magnetic disk 9 was prepared in the same manner as in Example 1, except that a suspension 10 in which the same PTFE particles 8 as in Example 1 were ultrasonically dispersed in a fluorinated solvent at a ratio of 4 wt% was used. Created. The size of the hills 7 on the magnetic disk in this example is the same as in Example 1, the average distance between adjacent pairs of hills is about 5 μm, and the number of hills 7 per unit area is about 100.
00 pieces/mm2, and the total area ratio of hills 7 was about 20%. Further, as a result of measuring the height of the hill 7 using a stylus type surface roughness meter, it was confirmed that the height of each hill 7 was approximately 15 nm.

As a result of conducting a CSS test on the magnetic disk 9 of this example, both the results of measuring the flying characteristics of the head and the results of observing dirt on the air bearing surface of the head were as excellent as in Example 1, and the results showed that the magnetic disk 9 could last for a long time. It was found that sliding reliability and head flying stability were ensured.

Example 4 Using the same suspension 10 as in Example 1 in which PTFE particles were dispersed, the suspension 10 was applied to the C protective film 5 by a dipping method using the apparatus shown in FIG. A magnetic disk 9 was produced in the same manner as in Example 1 except that it was attached to the surface. The size of the hills 7 of the magnetic disk 9 of this embodiment is the same as in Example 1, the average value of the distance between adjacent pairs of hills is about 15 μm, and the number of hills 7 per unit area is about 25.
00 pieces/mm2, and the total area ratio of hills 7 was about 5%. In addition, as a result of measuring the height of hill 7 with a stylus type surface roughness meter,
It was confirmed that both had a diameter of about 15 nm.

As a result of conducting a CSS test on the magnetic disk 9 of this example, both the head flying characteristic measurement results and the head flying surface dirt observation results were as excellent as in Example 1, and long-term sliding performance was confirmed. It was found to ensure reliability and flying stability of the head.

Example 5 A magnetic disk 9 was manufactured in the same manner as in Example 1, except that the protective film 5 was formed to a thickness of 30 nm by plasma CVD using a mixed gas of methane and hydrogen. did. The size of the hills 7 of the magnetic disk 9 in this embodiment is the same as in Example 1, the average value of the distance between adjacent pairs of hills 7 is about 15 μm, and the number of hills 7 per unit area is about 2.
500 pieces/mm2, and the total area ratio of hills 7 was about 5%. Further, as a result of measuring the height of the hills 7 using a stylus type surface roughness meter, it was confirmed that the heights of the hills 7 were all 15 nm.

As a result of conducting a CSS test on the magnetic disk 9 of this example, both the results of measuring the flying characteristics of the head and the results of observing dirt on the air bearing surface of the head were as excellent as in Example 1, and the results showed that it could last for a long time. It was found that sliding reliability and head flying stability were ensured.

Example 6 As in Example 1, a NiP base film 2, a Cr intermediate film 3, and a CoNi magnetic film 4 were formed on the surface of the aluminum alloy disk 1, and sputtering was performed on the NiP base film 2, Cr intermediate film 3, and CoNi magnetic film 4. A lower protective film 5' of SiC was formed to a thickness of 15 nm, and an upper protective film 5'' of C was formed to a thickness of 15 nm. Hill 7 was formed in the same manner as in Example 1. Under the etching conditions of this example, the etching rate of SiC is smaller than that of C, so even if the etching time is increased somewhat, the height of the hill 7 formed will be lower than that of the lower protective film 5 of C.
This embodiment has the effect that the height of the hill 7 can be easily controlled.The surface of the protective film 5 on which the hill 7 has been formed is coated with the same thickness as in Example 1, which is 15 nm. A lubricating film 6 was formed to produce a magnetic disk 9. The size of the hills 7 of the magnetic disk 9 of this example was the same as that of Example 1,
The average distance between adjacent pairs of hills 7 was about 15 μm, the number of hills 7 per unit area was about 2500/mm 2 , and the ratio of the total area of hills 7 was about 5%. Further, as a result of measuring the height of the hill 7 using a stylus type surface roughness meter, it was confirmed that the height of each hill was about 15 nm.

As a result of conducting a CSS test on the magnetic disk 9 of this example, both the head flying characteristic measurement results and the stain observation results on the head air bearing surface were as excellent as in Example 1, and long-term sliding resistance was observed. It was found that dynamic reliability and head flying stability were ensured.

<Example 8> The outer diameter of the substrate 1 was mirror-finished so that the average roughness (Ra) was 1.5 nm or less and the maximum roughness (Rmax) was 4 nm or less as measured by a stylus surface roughness meter. A 5.25-inch glass substrate was formed, and on this substrate 1, a Cr intermediate film 3 was formed with a thickness of 100 nm, a CoNi magnetic film 4 was formed with a thickness of 50 nm, and a C protective film 5 was formed with a thickness of 30 nm by sputtering in the same manner as in Example 1. They were formed respectively. As in Example 1, hills 7 were formed on the surface of the C protective film 5, and a lubricant film 6 was formed thereon to produce a magnetic disk 9. The size of the hills 7 of the magnetic disk 9 of this embodiment is the same as that of the first embodiment, and the average value of the distance between adjacent pairs of hills 7 is about 15
μm, the number of hills 7 per unit area is approximately 2500/mm
2. The total area ratio of Hill 7 was approximately 5%. In addition, as a result of measuring the height of hill 7 with a stylus type surface roughness meter, the height of hill 7 was 15.
It was confirmed that it was nm.

As a result of conducting a CSS test on the magnetic disk 9 of this example, both the results of measuring the flying characteristics of the head and the results of observing dirt on the air bearing surface of the head were as excellent as in Example 1, and the results showed that the magnetic disk 9 could last for a long time. We were able to ensure sliding reliability and flying stability of the head.

<Comparative Example 1> Same as Example 1, outer diameter 5.2
A NiP base film 2 was formed on the surface of a 5-inch aluminum alloy disk 1 to a thickness of 15 μm by electroless plating, and the base film 2 was polished to a thickness of 10 μm and measured using a stylus type surface roughness meter. A substrate was formed by mirror-finishing so that the average roughness (Ra) measured by the method was 2 nm or less and the maximum roughness (Rmax) was 5 nm or less. On this substrate, a Cr intermediate film 3 with a thickness of 100 nm and a CoNi magnetic film 4 with a thickness of 5 nm are deposited by sputtering.
A protective film 5 of 0 nm and C was formed to have a thickness of 30 nm. In this comparative example, the magnetic disk 9 was manufactured by directly forming the lubricating film 6 without forming the hills 7 on the surface of the C protective film 5.

The minimum guaranteed flying height of the head 13 with respect to the magnetic disk 9 manufactured in this comparative example was 0.04 μm or less, and a magnetic disk device could be obtained even with the flying height of the head 13 of 0.08 μm. However, when the magnetic disk 9 manufactured in this comparative example was subjected to a CSS test using the apparatus shown in FIG. 5, scratches appeared on the disk surface after 10,000 CSS operations, and sliding reliability was poor. . Regarding another magnetic disk 9 manufactured in the same manner, CS
When the minimum guaranteed flying height of the head 13 was measured after 5000 S operations, it had deteriorated to 0.1 μm. As a result of observing the air bearing surface of the head 13, it was found that dirt that had not been seen before the test had adhered to the air bearing surface, and that this was deteriorating the flying characteristics. These results revealed that the magnetic disk 9 of this comparative example was unable to ensure long-term sliding reliability and flying stability of the head.

<Comparative Example 2> Same as Example 1, outer diameter 5.2
A NiP base film 2 was formed on the surface of a 5-inch aluminum alloy disk 1 to a thickness of 15 μm by electroless plating, and the base film 2 was polished to a thickness of 10 μm and measured using a stylus type surface roughness meter. A substrate was formed by mirror-finishing so that the average roughness (Ra) measured by the method was 2 nm or less and the maximum roughness (Rmax) was 5 nm or less. On this substrate, a Cr intermediate film 3 with a thickness of 100 nm and a CoNi magnetic film 4 with a thickness of 50 nm are deposited by sputtering.
The C protective film 5 was formed to have a thickness of 40 nm. In this comparative example, while rotating the disc, a buff containing abrasive grains was pressed onto the surface of the protective film 5 of C for about 10n.
Polishing was performed to a depth of m to form a groove extending in the circumferential direction. The surface of the C protective film 5 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) was 30 nm. A magnetic disk 9 was manufactured by forming a lubricating film 6 on the surface of the protective film 5 of C.

The minimum guaranteed flying height of the head 13 with respect to the magnetic disk 9 manufactured in this comparative example was 0.09 μm, and the flying stability of the head 13 on the disk 9 was poor.
Application to a magnetic disk device with a flying height of 0.08 μm was impossible. The magnetic disk 9 manufactured in this comparative example was
As a result of conducting a CSS test using the apparatus shown in Figure 5, 30
After 000 CSS operations, scratches occurred on the disk surface, and the sliding reliability was insufficient. In addition, when we measured the minimum guaranteed flying height of the head 13 after 20,000 CSS operations for another magnetic disk 9 manufactured in the same manner, it was found to be 0.1.
It further worsened to 4 μm. As a result of observing the air bearing surface of the head 13, it was found that dirt that had not been seen before the test had adhered to the air bearing surface, which further deteriorated the flying characteristics. These results revealed that the magnetic disk 9 of this comparative example was unable to ensure long-term sliding reliability and flying stability of the head.

<Comparative Example 3> Same as Example 1, outer diameter 5.2
A NiP base film 2 was formed on the surface of a 5-inch aluminum alloy disk 1 to a thickness of 15 μm by electroless plating, and the base film 2 was polished to a thickness of 10 μm and measured using a stylus type surface roughness meter. A substrate was obtained by mirror-finishing the substrate so that the average roughness (Ra) was 2 nm or less and the maximum roughness (Rmax) was 5 nm or less. Cr was deposited on this substrate by sputtering.
The intermediate film 3 is 100 nm thick, and the CoNi magnetic film 4 is 50 nm thick.
Protective films 5 of M and C were each formed to a thickness of 60 nm. In this comparative example, no particles were allowed to adhere to the surface of the C protective film 5, and the C protective film 5 was etched by 30 nm under conditions where the reverse sputtering power was doubled compared to Example 1, and then the lubricating film 5 was etched by 30 nm. A magnetic disk 9 was manufactured by forming the following. Many minute protrusions were formed on the surface of the C protective film 5 after etching. The size of the protrusions is approximately 0.05 μm, the average height is 10 nm, and the average spacing between adjacent pairs of protrusions is approximately 0.4 μm.
, the number of protrusions per unit area is approximately 2.5 x 107 pieces/m
m2, the total area ratio of protrusions was approximately 5%.

The guaranteed minimum flying height of the head 13 for the magnetic disk 9 manufactured in this comparative example was 0.06 μm, and application to a magnetic disk device with a flying height of 0.08 μm was possible. The magnetic disk 9 manufactured in this comparative example was
As a result of conducting a CSS test using the apparatus shown in Figure 5, 25
After 000 CSS operations, scratches occurred on the disk surface, and the sliding reliability was insufficient. In addition, when we measured the minimum guaranteed flying height of the head 13 after 20,000 CSS operations for another magnetic disk 9 manufactured in the same manner, it was found to be 0.1.
It had worsened to 2 μm. As a result of observing the air bearing surface of the head 13, it was found that dirt that had not been seen before the test had adhered to the air bearing surface, and that this was deteriorating the flying characteristics. From this result, the magnetic disk 9 of this comparative example in which extremely small and dense protrusions were formed could not ensure long-term sliding reliability and flying stability of the head.

<Comparative Example 4> Same as Example 1, outer diameter 5.2
A NiP base film 2 with a thickness of 15 μm was formed on the surface of a 5-inch aluminum alloy disk 1 by electroless plating, and the base film 2 was polished to 10 μm and measured using a stylus surface roughness meter. The substrate was mirror-finished so that the average roughness (Ra) was 2 nm or less and the maximum roughness (Rmax) was 5 nm or less. On this substrate, a Cr intermediate film 3 of 100 nm thickness, a CoNi magnetic film 4 of 50 nm thickness, and a C
A protective film 5 of 30 nm thick was formed respectively. Hills were formed on the surface of the protective film 5 of C by the following method.

A suspension of polytetrafluoroethylene (PTFE) particles 8 having an average particle size of 50 μm at a ratio of 1 wt % in a fluorinated solvent was prepared by ultrasonic dispersion, and a protective film 5 of C was prepared in the same manner as in Example 1. PTFE particles 8 are coated with a C protective film 5 on the surface.
It was dispersed and attached on top. As a result of observing the adhesion state of the PTFE particles 8 using an optical microscope, the size of the adhesion particles 8 was 4.
More than 90% of the total number of particles are 0-60μm, and 8
The average interval between particles 8 was about 150 μm, the density of particles 8 per unit area was about 25 particles/mm 2 , and the total area ratio of the covered part of particles 8 was about 5%. This disk was reverse sputtered using a sputtering device in the same manner as in Example 1 to form a C protective film 5 of 15 nm.
After etching, the surface is scrubbed with pure water,
PTFE particles 8 were removed. From the surface observation results before and after etching, it was confirmed that hills 7 of approximately the same size as the attached particles were formed on the surface of the C protective film 5. The average distance between the hills 7 after etching was about 150 μm, the density of the hills 7 per unit area was about 25/mm 2 , and the total area ratio of the hills was about 5%. Further, as a result of measuring the height of the hill 7 using a stylus type surface roughness meter, it was confirmed that the height of each hill was about 15 nm.

A perfluoropolyether lubricant film 6 of about 5 nm thickness was applied to the surface of the disc thus obtained to produce a magnetic disk 9.

The minimum guaranteed flying height of the head 13 for the magnetic disk 9 manufactured in this comparative example was 0.06 μm, and application to a magnetic disk device with a flying height of 0.08 μm was possible. The magnetic disk 9 manufactured in this comparative example was
As a result of conducting a CSS test using the apparatus shown in Figure 5, 30
After 000 CSS operations, scratches occurred on the disk surface, and the sliding reliability was insufficient. In addition, when we measured the minimum guaranteed flying height of the head 13 after 20,000 CSS operations for another magnetic disk 9 manufactured in the same manner, it was found to be 0.1.
It had worsened to 2 μm. As a result of observing the air bearing surface of the head 13, it was found that dirt that had not been seen before the test had adhered to the air bearing surface, and that this was deteriorating the flying characteristics. From this result, the magnetic disk 9 of this comparative example in which large and sparse hills 7 were formed could not ensure long-term sliding reliability and flying stability of the head.

Regarding the magnetic disk 9 shown in the above Examples and Comparative Examples, Examples 1 to 3 and A magnetic disk 9 of Comparative Example 1-4 was prepared in the same manner, and an acceleration test was conducted using the apparatus shown in FIG. 7 by introducing atmospheric dust. After the test, the amount of dirt adhering to the air bearing surface was evaluated relative to the adhering area. When the amount of dirt attached to the air bearing surface of the magnetic disk of Comparative Example 1 is set to 100, the amount of dirt attached to the air bearing surface of each magnetic disk is 2 or less in all of Examples 1 to 3, and the amount of dirt attached to the air bearing surface of each magnetic disk is 2 or less in the case of Examples 1 to 3. It was found that the effect of preventing dirt from adhering to the disc was significant. On the other hand, when minute and dense unevenness is formed on the disk surface as in Comparative Examples 2 and 3, the amount of dirt attached is about 50 in both cases, and compared to Comparative Example 1 where no unevenness is formed on the protective film surface, the amount of dirt attached However, the stain adhesion prevention effect was insufficient compared to the present invention. On the other hand, in Comparative Example 4, where large and sparse hills are formed on the disk surface, the amount of dirt adhering is approximately 40, which is less than Comparative Example 1 in which no unevenness is formed on the protective film surface. Compared to the invention, the stain adhesion prevention effect was insufficient.

[0129]

According to the present invention, dirt adhering to the flying surface of the head can be effectively removed from the surface of the protective film of the magnetic disk, so even when the flying height of the head is small, long-term head sliding can be prevented. Dynamic reliability and head flying stability can be ensured. As a result, a magnetic disk device with high reliability and high recording density can be obtained.

[Brief explanation of drawings]

FIG. 1 is a schematic diagram showing the cross-sectional shape of a magnetic disk according to an embodiment of the present invention.

FIG. 2 is a schematic plan view showing a typical arrangement of hills formed on the surface of a magnetic disk according to an embodiment of the present invention.

FIG. 3 is a schematic diagram showing a method of forming hills on the surface of a protective film of a magnetic disk according to an embodiment of the present invention.

FIG. 4 is a schematic diagram illustrating a method and apparatus for attaching solid particles to the surface of a protective film of a magnetic disk according to an embodiment of the present invention.

FIG. 5 is a schematic diagram illustrating a method and apparatus for attaching solid particles to the surface of a protective film of a magnetic disk according to an embodiment of the present invention.

FIG. 6 is a schematic diagram showing the configuration of a magnetic disk device according to an embodiment of the present invention.

FIG. 7 is a schematic diagram showing the configuration of an apparatus for evaluating the amount of dirt attached to the air bearing surface of a magnetic head used in the present invention.

FIG. 8 is a schematic diagram showing the effect of removing dirt attached to the head air bearing surface by hills formed on the surface of the magnetic disk of the present invention.

[Explanation of symbols]

1... Aluminum alloy disk, 2... Base film, 3... Intermediate film,
4... Magnetic film, 5... Protective film, 6... Lubricating film, 7... Hill formed on the surface of the protective film, 8... Solid particle, 9... Magnetic disk, 1
0... Suspension in which solid particles are dispersed, 11... Nozzle, 12
...pump, 13...magnetic head, 14...carriage, 15
...Voice coil motor, 16...Spindle motor, 17
...Case, 18...Filter, 19...Dirty adhering to the air bearing surface.

Claims (14)

[Claims] Claim 1: A magnetic disk having a magnetic film and a protective film on a substrate, wherein the surface of the protective film has the following (a) to (c).
A magnetic disk characterized in that it has a hill comprising. (a) The height of the hill is substantially uniform and is in the range of 5 to 40 nm. (b) There is a distribution in the size of the hill, and the equivalent diameter is 0.1
80% or more of the entire area should have hills of ~30 μm. (c) 50 to 2.5 x 105 hills per unit area/
mm2 must exist. 2. A magnetic disk having a magnetic film and a protective film on a substrate, wherein the protective film has portions with different thicknesses,
The thickness difference between the thick part of the protective film and the thin part of the protective film is 5 to 40 nm, the thick part of the protective film satisfies the following (a) and (b), and the thin part of the protective film is A magnetic disk characterized by being dispersed within a part. (a) There is a distribution in the size of the thick portion of the protective film, with 80% or more of the thick portion having an equivalent diameter of 0.1 to 30 μm. (b) The thick portion of the protective film has a thickness of 50 to 2.0 mm per unit area.
There should be 5 x 105 pieces/mm2. 3. In a magnetic disk having a magnetic film and a protective film on a substrate, the following (a) to (c) are applied to the surface of the protective film.
A magnetic disk characterized in that it has a region in which hills are formed. (a) The height of the hill is substantially uniform and is in the range of 5 to 40 nm. (b) There is a distribution in the size of the hill, and the equivalent diameter is 0.1
80% or more of the entire area should have hills of ~30 μm. (c) The ratio of the total area of the hills in the area is 0.
Must be between 5 and 60%. 4. In a magnetic disk having a magnetic film and a protective film on a substrate, the following (a) to (c) are applied to the surface of the protective film.
A magnetic disk characterized in that it has a hill comprising. (a) The height of the hill is substantially uniform and is in the range of 5 to 40 nm. (b) There is a distribution in the size of the hill, and the equivalent diameter is 0.1
80% or more of the entire area should have hills of ~30 μm. (c) The average value of the distance between the hill and the adjacent hill is 1 to
Must be 80 μm. 5. The magnetic disk according to claim 1, wherein the protective film and the hills formed on the surface of the protective film are made of the same material. 6. A step of forming a magnetic film on a substrate, a step of forming a material to serve as a protective film on the magnetic film, and a step of dispersing and adhering particles having a size distribution on the surface of the material. , etching the material using the particles as a mask so that the magnetic film is not exposed to form hills of approximately uniform height; removing the particles so that the surface has a distribution in size and spacing; 1. A method for manufacturing a magnetic disk, comprising: forming a protective film having hills of approximately uniform height. 7. The method of manufacturing a magnetic disk according to claim 6, wherein the particles are made of a fluororesin or a material containing at least carbon and fluorine. 8. A magnetic disk device using the magnetic disk according to claim 1, 2, 3, or 4. 9. A magnetic disk device that records and reproduces information by flying a magnetic head above a magnetic disk, wherein the distance between the magnetic disk and the magnetic head during recording and reproduction is 0.01 to 0.15 μm. The magnetic disk has a substantially uniform height of 5 to 40 nm, and has a height of 100 to 5×10 5 with respect to the area of the air bearing surface of the magnetic head.
What is claimed is: 1. A magnetic disk device characterized by having a plurality of hills. 10. A magnetic disk device for recording and reproducing information by floating a steam head above a magnetic disk, wherein a distance between the magnetic disk and the magnetic head during recording and reproducing is 0.01 to 0.15 μm. The magnetic disk device is characterized in that the magnetic disk has a substantially uniform height of 5 to 40 nm and has 50 to 2.5×10 5 hills/mm 2 per unit area. 11. A magnetic disk device for recording and reproducing information by flying a magnetic head above a magnetic disk, wherein the magnetic disk has a substantially uniform height of 5 to 40 nm and an equivalent diameter of 0.1 to 30 μm. 80% of the total
or more, 50 to 2.5 x 105 pieces/mm per unit area
2 hills and a recording density of 100 per square inch.
A magnetic disk device characterized in that it has a capacity of ~5000 Mbits. 12. A magnetic disk device for recording and reproducing information by flying a magnetic head above a magnetic disk, characterized in that the magnetic disk surface has a hill for removing dirt attached to the flying surface of the magnetic head. magnetic disk device. 13. A magnetic disk having a protective film, a rotating means for rotating the magnetic disk, a magnetic head facing the magnetic disk during rotation, and moving the magnetic head to a desired position on the magnetic disk. and positioning means for positioning the magnetic head, the magnetic disk having a convex portion, the convex portion having a substantially uniform height of 5 to 40 nm, and the convex portion having a height of 5 to 40 nm. A magnetic disk device characterized in that 80% or more of the magnetic disks have an equivalent diameter of 0.1 to 30 μm, and there is a size distribution. 14. The magnetic disk according to claim 1, wherein the surface of the protective film having the hills has a lubricating film having a thickness thinner than the height of the hills.