JPH03295086A - Magnetic disk device and magnetic recording medium - Google Patents

Abstract

PURPOSE:To maintain the floating stability of a magnetic head over a long period by making a part surrounded by plural slots to be flat substantially, selecting a ratio of integrated area of projections in projection regions to be a specific range and selecting the height of the projections to be within a prescribed height. CONSTITUTION:Plural continuous or discontinuous slots are provided on the surface of a disk 14 and parts surrounded by the slots are formed substantially flat. Then a ratio of integrated area of projections 7 in the unit of area in projection regions is selected to be 0.5% or over and 90% or below, and the height of the projections is selected to be almost same within a range higher than 5nm and lower than 40nm. Moreover, the magnetic disk 14 and the magnetic head are opposite to each other during rotation at a minute gap of 0.01 - 0.2mum and supported by a slider. Then the floating quantity of the head is selected to be 0.15mum or below to make the recording density of the magnetic disk 14 high.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a magnetic recording device and a magnetic recording medium used therein.

[Conventional technology]

In recent years, the importance of magnetic recording devices as external storage devices for computer systems has been increasing, and the recording density thereof has been significantly improved year by year. Thin-film magnetic recording media that use magnetic thin films are attracting attention as magnetic recording media that can support such higher recording densities, instead of the conventional coated media that coats a substrate with magnetic paint made by mixing magnetic powder and binder. ing.

Thin-film magnetic recording media (hereinafter referred to as
The general structure of a magnetic recording medium (simply referred to as a magnetic recording medium) is as follows. The substrate consists of an aluminum alloy disk and a hard underlayer formed thereon.

If a disk material with high hardness, such as glass, is used instead of aluminum alloy, the base layer may be omitted. A magnetic layer is formed on the substrate, and an intermediate layer may be formed between the two for the purpose of improving adhesion and improving the characteristics of the magnetic layer. A protective layer and, if necessary, a lubricating layer are formed on the magnetic layer to constitute a magnetic recording medium.

A magnetic recording device consists of a magnetic recording medium and a recording/reproducing magnetic head (
The main components are a magnetic recording medium rotation control mechanism, a head positioning mechanism, and a recording/reproduction signal processing circuit.

In this recording and reproducing method, the head and the magnetic recording medium are in contact before the start of operation, but by rotating the magnetic recording medium, a space is created between the head and the magnetic recording medium, and recording and reproducing are performed in this state. . At the end of the operation, the magnetic recording medium stops rotating and the head and magnetic recording medium are brought into contact again. This is the contact start/stop method.
Hereinafter, this method will be referred to as the C3S method. In order to improve the recording density of a magnetic recording device, the smaller the flying height of the head during recording and reproduction, the better.In order to ensure the flying stability of the head at that time, the surface of the magnetic recording medium should be as flat as possible. This is required.

Incidentally, the frictional force generated between the head and the magnetic recording medium when the apparatus is started and stopped causes wear of both, causing characteristic deterioration. Furthermore, if moisture is present between the head and the magnetic recording medium while the magnetic recording medium is stationary, the two will be strongly attracted to each other, and if the head is started in this state, a large force will be generated between the head and the magnetic recording medium. This may cause damage to the head or magnetic recording medium. The frictional force and adsorption force described in 2. tend to increase as the surface of the magnetic recording medium becomes flatter, which conflicts with the above-mentioned requirement for flying stability of the head accompanying the increase in recording density.

In order to reduce such frictional force and adsorption force.

A method of forming minute irregularities on the surface of a magnetic recording medium is commonly used.

Various such methods have been proposed, including, for example, a method of forming minute irregularities on a nonmagnetic substrate using an abrasive tape, and a method of forming minute irregularities on the surface of a protective layer. For example, on the surface of a magnetic recording medium on which a protective layer is formed,
A method of forming irregularities on the surface of a protective layer by irradiating gaseous ions is proposed in JP-A-58-53026. In addition, Japanese Patent Laid-Open No. 62-2224 discloses a method of forming irregularities within a range not exceeding the thickness of the protective layer on the surface of a magnetic recording medium on which a protective layer is formed by polishing, wet etching, or dry etching.
It is proposed in No. 1. Furthermore, Japanese Patent Laid-Open No. 13227/1983 proposes a method of polishing the surface of the protective layer while rotating the magnetic recording medium to form concentric irregularities.

[Problem to be solved by the invention]

All of the above conventional technologies aim to reduce the frictional force and adsorption force of the magnetic head against the magnetic recording medium to prevent the magnetic head support slider from adhering to the magnetic recording medium, thereby stabilizing the flying of the magnetic head. No consideration is given to sustaining sex over a long period of time.

An object of the present invention is to provide a magnetic recording medium in which the flying stability of a magnetic head can be maintained over a long period of time.

Another object of the present invention is to provide a magnetic disk device and system equipped with a magnetic recording medium that achieves the above object.

Still another object of the present invention is to reduce the flying height of the magnetic head to 0.1.
It is an object of the present invention to provide a magnetic disk device, a system, and a magnetic recording medium therefor, which can have a thickness of 5 μm or less and maintain flying stability for a long period of time.

[Means to solve the problem]

The magnetic disk device of the present invention essentially includes at least one magnetic disk having a magnetic layer and a surface protective layer on a substrate, opposed to the rotating magnetic disk with a small gap, and supported by a slider. A magnetic disk device comprising a magnetic head that rotates the magnetic disk, a rotating means that rotates the magnetic disk, and a magnetic head positioning means that moves and positions the magnetic head to a predetermined position on the magnetic disk. It is characterized in that a structure having the following (a) and (b) is formed on the surface.

(a) A plurality of continuous or discontinuous grooves are provided, and a region surrounded by the plurality of grooves has a substantially flat surface.

(b) In the convex formation region, the cumulative area ratio of the convex portions per unit area is 0.5% or more and 90% or less,
and the height of the convex portion is higher than 5 nm (lower than 40 nm, and has a substantially constant height within that range).

The present invention provides the above (a) on the surface of a magnetic recording medium.

This is based on the investigation of the fact that by providing (b), the flying height of the magnetic head can be reduced and the flying stability can be maintained.

Due to the effects based on (a) and (b), it becomes possible to set the flying height of the magnetic head to be extremely small, and moreover, it becomes possible to maintain the flying height of the magnetic head almost constant. In particular, it is important to control both the hill area ratio and the height of the convex portions formed on the surface within a certain range, but all of the conventional techniques focus on both the hill area ratio and the height. The concept of controlling the value within a specified value is not mentioned.

The importance of the above technique becomes particularly significant as the flying height of the head is reduced to increase the recording density of a magnetic disk device, for example, when the flying height is set to 0.15 μm or less.

[Effect]

According to the present invention, firstly, only the hill portion directly faces the head, and the area ratio of the magnetic recording medium in contact with the head can be reduced, so that the frictional force and attraction force with the head can be reduced. . Second, by regularly arranging the hills that are formed, there is less fluctuation in the flying height of the head, ensuring head flying stability over the entire surface of the magnetic recording medium, and preventing output fluctuations due to fluctuations in the flying height. can.

As described above, according to the present invention, it is possible to reduce the frictional force and adsorption force with the head, prevent output fluctuations, and ensure stable flying of the head, resulting in high recording and reproducing accuracy and high recording density. It is possible to obtain a magnetic recording medium and a magnetic recording device using the same that can cope with the reduction in the flying height of the head accompanying this.

Third, by arranging the formed hills regularly so that fine dust attached to the head or magnetic recording medium can be quickly removed, head crashes due to fine dust are less likely to occur, and the head can be maintained for a long time. It is possible to ensure floating stability.

As described above, according to the present invention, it is possible to ensure stable flying of the helad over a long period of time, thereby achieving high recording and reproducing accuracy, and also being able to cope with the reduction in the flying height of the head that accompanies the increase in recording density.
Moreover, a magnetic recording medium having long-term durability and a magnetic recording device using the same can be obtained.

〔Example〕

The present invention will be explained in detail below.

It is important that the hills formed on the surface of the protective layer or the nonmagnetic substrate are regularly arranged and that their heights are controlled within a specified value. As a result, the area ratio of the hills facing the head can be arbitrarily controlled over the entire surface of the magnetic recording medium, so that the flying height of the head can be stably controlled over the entire surface of the magnetic recording medium, and output fluctuations due to fluctuations in the flying height can be suppressed.

In particular, at least at any point on the same circumference with respect to the rotation center of the magnetic recording medium, if the area ratio of the hill is kept almost constant within the size range of the head slider, the head can be moved to a certain track position. When the magnetic recording medium is stationary and rotated, the head always faces the hill at approximately the same area ratio within the size range of the slider, making it possible to suppress fluctuations in flying height. In addition, if the area ratio of the hills is made to be approximately constant over the entire surface of the hill forming part within the size range of the head slider, even when the magnetic recording medium is rotated and the head is moved, the head will remain stable. Within the size range of the slider, the area ratio to the hill is always approximately the same, and fluctuations in flying height can be kept low over the entire surface. However, depending on the rotation of the magnetic recording medium, the linear velocity differs between the inner and outer peripheries, so if necessary, the area ratio of the hills may be continuously changed little by little from the inner periphery to the outer periphery. good.

In addition, the hills formed on the surface of the protective layer and the nonmagnetic substrate are
It is desirable that it is discontinuous at least on the same circumference of the magnetic recording medium. This is because when the head is stationary and the magnetic recording medium is rotated, the head will intermittently move against a hill when viewed from one point, so even if minute dust adheres to the head, it will be easily removed. It is.

In addition, the hills formed on the surface of the protective layer and the nonmagnetic substrate are
It is desirable that at least part of the discontinuous linear or pit-like portions without hills be smoothly continuous from the inner circumference to the outer circumference of the magnetic recording medium within the moving region of the head. This is because even if fine dust enters between the head and the magnetic recording medium, the fine dust is likely to be removed toward the outer circumferential side by centrifugal force along the hill-free portion.

A specific hill arrangement that satisfies all of the above conditions is as follows. For example, linear or pit-like hills formed from a part of a concentric circle or a spiral arc are regularly arranged over the entire surface of the magnetic recording medium with respect to the center of rotation or the center of a pattern intentionally shifted from the center of rotation. It is preferable that the hills are arranged so that at least a part of the hill-free portion smoothly continues from the inner circumference to the outer circumference of the magnetic recording medium within the movement area of the head. To give a more specific example, for example, with a width of 1 μm and a pitch of 20 μm, the magnetic recording medium is spirally arranged around the rotation center of the magnetic recording medium, for example, at every 0.1 degree in the center angle, by 0.05 degrees in the center angle.
It is an arc-shaped hill formed over the entire surface. It is desirable that the spiral arc array is offset by at least 4 degrees with respect to the concentric circles. The reason for this is to avoid overlapping with the magnetic recording track and influencing the recording/reproduction signal.

An example of the hill arrangement pattern shown here is schematically shown in FIG. In this specific example, the cut portion of the hill continues linearly from the inner circumference to the outer circumference of the magnetic recording medium, so even if minute dust enters between the head and the magnetic recording medium,
Microscopic dust is easily removed to the outer periphery due to centrifugal force. In order to make the diagram easier to read, the scale of FIG. 1 is different from the actual scale, and the actual shape is a shape with many arcuate hills arranged over the entire surface as shown in FIG. 1. Among the above arrangements, when linear or pit-shaped hills made of part of a concentric circular arc are arranged regularly over the entire surface of the pattern center, which is intentionally shifted from the spiral or rotation center. This is particularly desirable because when the head is stationary and the magnetic recording medium is rotated, the hill acts like a wiper when viewed from a certain point on the head, and is highly effective in removing minute dust adhering to the head. Furthermore, although the spiral shape may be a single layer as in the specific example above, if it is a multiple spiral structure, the angle between the arc of the formed hill and the circumference with respect to the center of rotation will become larger, which will reduce the amount of dust attached to the head. The effect of removing will be greater.

As another example, it is preferable that pit-shaped hills are regularly arranged over the entire surface in the portions corresponding to the vertices of a regular lattice pattern. To give a more specific example, pit-like hills of, for example, 2 μm in diameter are arranged over the entire surface at portions corresponding to the intersections of square lattices with a pitch of, for example, 10 μm.

An example of the hill arrangement pattern shown here is schematically shown in FIG. Note that in order to make the diagram easier to read, the scale of FIG. 2 is different from the actual scale, and the actual shape is that many pit-shaped hills are arranged over the entire surface as shown in FIG. 2. The lattice pattern used here may be any pattern regularly drawn, such as a triangular lattice or a hexagonal lattice, in addition to the above-mentioned square lattice. When the hills are arranged in this way, when the head is stationary and the magnetic recording medium is rotated, the hills appear intermittently when viewed from one point on the head, which has the effect of removing minute dust attached to the head. is large. In addition, in this example, the gaps between the hills formed at the vertices of the lattice are linearly continuous from the inner circumference to the outer circumference of the magnetic recording medium, allowing microscopic dust to enter between the head and the magnetic recording medium. Even in this case, microscopic dust is likely to be removed to the outer circumferential side due to centrifugal force.

In addition to the above, it is arranged regularly so as to have the effect of removing minute dust attached to the magnetic head and the effect of removing minute dust interposed between the magnetic recording medium and the magnetic head in the direction of the outer circumference of the magnetic recording medium. Any other arrangement is acceptable as long as the hill is

The height of the hills formed in the pattern shown above is 5n
m or more and 50 nm or less, preferably 10 nm or more and 40 nm
It is desirable that it be approximately constant within the following range. If the height of the hill is less than 5 nm, the effect of reducing the frictional force and attraction force between the head and the magnetic recording medium will be reduced. The height of the hill is 50
If it is more than nm, the distance between the head and the magnetic layer becomes large during recording and reproduction, resulting in a decrease in output and impairing the flying stability of the head. Moreover, it is not preferable that the height of the hill is uneven because the high part becomes a protrusion.

Further, the width of the formed hill in the radial direction is preferably 0.1 μm or more and 10 μm or less, preferably 0.3 μm or more and 3 μm or less. If the width of the hill is 0.3 μm or less, it will be difficult to obtain precision during ratio formation. If the width of the hill is 3 μm or more, the effect of reducing the frictional force and attraction force between the head and the magnetic recording medium becomes small.

The area ratio of the hills formed is 0.5% or more and 90% or less,
Preferably it is 10% or more and 80% or less. When the area ratio of the hills is less than 0.5%, the head is supported by a small area, so the hill portions are prone to wear and long-term sliding durability is reduced. If the area ratio of the hills is 90% or more, the effect of reducing the frictional force and attraction force between the head and the magnetic recording medium becomes small.

The point that must be emphasized here is that it is important to control both the area ratio of the hill formed and the height of the hill within the above specified values.

FIG. 3 shows the relationship between the area ratio of the formed hills and the minimum flying circumferential speed of the magnetic head (the lowest flying circumferential speed at which the magnetic head does not come into contact with the protrusion on the magnetic recording medium). This result shows that when the area ratio of hills formed on the magnetic recording medium surface is small,
This indicates that it is difficult to stably fly the head when the minimum flying peripheral speed of the head is high, that is, when the spacing between the head and the magnetic recording medium is small.

Furthermore, Fig. 4 shows samples in which the area ratio of the hills formed on the surface of the magnetic recording medium is kept constant and the depth of the grooves is varied.
This result shows the difference in frictional force when performing the C8S test as a sliding resistance test.This result shows that in order to reduce the frictional force and improve sliding performance, the groove depth, that is, the height of the hill, must be adjusted within a certain range. This indicates that it must be controlled.

As shown above, by controlling both the pressure area ratio and the height of the hill within the specified values, both head flying stability and adhesion force reduction can be achieved even when the head flying height is small. This makes it possible to maintain high performance, resulting in a high-performance and highly reliable magnetic disk device.

The area in which the hills are formed on the surface may be the entire surface of the magnetic recording medium, but if the C8S zone is exclusively provided due to the specifications of the magnetic recording device in which the magnetic recording medium is installed, the hills may be formed only in that part. Good too. The reason for this is that the frictional force with the head, the adsorption force, the influence of fine dust, etc., as mentioned above, mainly cause problems when starting and stopping the magnetic recording device, and the head does not float stably. This is because the effect of forming hills is small in this state.

Furthermore, in a system in which the magnetic head is positioned on a dedicated magnetic recording medium surface, the shape of the present invention can be formed only on that surface.

A specific method for forming the magnetic recording medium according to the present invention is as follows. A method for forming hills on a mirror-finished non-magnetic disk or on the surface of a protective layer is to form a desired mask pattern on the non-magnetic disk or on the surface of the protective layer using lithography technology, and then perform etching. A preferred method is to selectively and uniformly etch only the portions not covered by the mask pattern to a certain depth, and then remove the mask pattern. The etching method used here is selected from dry etching such as ion milling and reactive plasma treatment, wet etching, and the like.

Another method for forming hills is to form a film of a substance that can be hardened by beam irradiation with light, laser, or charged particles on a nonmagnetic disk or the surface of a protective layer, and then apply light or light to the film surface.
It can also be formed in the same way by regularly irradiating a laser or a beam of charged particles to a desired position to partially cure it, and then removing the uncured portion.

Note that other methods than the above-mentioned method may be used as long as the shape of the hill finally obtained is desired. For example, after forming a magnetic layer and a protective layer on a mirror-finished nonmagnetic disk, a photodegradable organometallic gas is introduced.
Hills of a similar shape can also be formed by a method such as a method (laser CVD method) in which metal is selectively deposited by periodically and regularly irradiating a laser beam.

FIG. 5 shows an outline of the magnetic disk device. The magnetic disk drive includes components 8 to 15 shown in FIG. 5 and a voice coil motor control circuit. Reference numeral 11 is a base, and reference numeral 12 is a spindle.

A plurality of disc-shaped magnetic disks 14 are attached to one spindle as shown in the figure. Although FIG. 5 shows an example in which five magnetic disks 14 are provided on one spindle, the number is not limited to five. Further, a plurality of magnetic disks 14 may be installed on one spindle 12 in this way. Reference numeral 13 is a motor for driving the spindle 12 and rotating the magnetic disk;
That is, it is a magnetic disk rotation control means. Reference numeral 15 indicates a data magnetic head, and reference numeral 15a indicates a positioning magnetic head. Code 16 is a carriage, code 17
18 is a voice coil, and 18 is a magnet. The voice coil 17 and magnet 18 constitute a voice coil motor.

And code 16. Code 17. The element 18 positions the head. Therefore, numerals 16, 17 .
18 is collectively referred to as a magnetic head positioning mechanism. The voice coil 17 and the magnetic heads 15 and 15a are connected via a voice coil motor control circuit.

In FIG. 5, the host device is, for example, a computer system, which has a function of processing information recorded on a magnetic disk device. In this recording and reproducing method, the magnetic head and the magnetic recording medium are in contact before the start of operation, but a space is created between the magnetic head and the magnetic recording medium by rotating the magnetic recording medium, and recording and reproducing is performed in this state. I do.

At the end of the operation, the rotation of the magnetic recording medium stops, and the magnetic head and the magnetic recording medium are brought into contact again.

This is the contact start/stop method (C5S
method).

The present invention will be explained in more detail with reference to more specific examples below.

<Example 1> An N1-P base film was formed to a thickness of 15 μm by electroless plating on the surface of an aluminum alloy disk with an outer diameter of 5.25 inches, and the base film was polished to a thickness of 10 μm to form a stylus-type surface. The average roughness (Ra) measured with a roughness meter is 4 nm, and the maximum roughness (R
max) Mirror-finishing was performed so that the thickness was 10 nm or less.

On the substrate thus obtained, a Cr intermediate layer with a thickness of 0.2 μm, a Co-Ni magnetic layer with a thickness of 40 nm, and a C
A protective layer was formed to a thickness of 20 nm.

A positive resist (Tokyo Ohka layer, 0FP) is applied to the surface of the C protective layer.
R800) was applied to a thickness of about 0.5 μm, exposed to light using a photomask formed in the shape shown in Fig. 1 so that only the hill portions did not pass through, and then developed. A mask pattern having the shape shown in FIG. 1 with resist remaining only in the hill portions was formed.

The entire surface of this disk is irradiated with an argon ion beam for 30 seconds using an ion milling device to uniformly etch the areas where no mask pattern is formed, and then the mask pattern is removed using a resist removal solution to protect the disk. Formed regularly arranged hills on the surface of the layer.

A perfluoropolyether lubricant was applied as a lubricant layer to a thickness of about 5 nm on the surface of the disk thus obtained to produce a magnetic recording medium. The height of the formed hill was measured at ten arbitrary points on the surface of the magnetic recording medium using an STM (scanning tunnel microscope I) and a stylus surface roughness meter. When the surface of the magnetic recording medium was measured by Auger electron spectroscopy, Co and Ni were not detected, confirming that there was no exposed portion of the magnetic layer.

FIG. 6 shows a schematic diagram of the cross-sectional structure in the radial direction of the magnetic recording medium of this example. In this example, the area ratio of the hills is 2.5% over the entire surface.

Example 2 A magnetic recording medium was produced in the same manner as in Example 1, except that the thickness of the C protective layer was 30 nm and the etching time by ion milling to form hills was 1 minute. S
The height of the hill was measured at ten arbitrary points on the surface of the magnetic recording medium using a TM and a stylus surface roughness meter, and the height of the hill was 20 nm at all measurement points.

Example 3 A magnetic recording medium was produced in the same manner as in Example 1, except that a photomask having the shape shown in FIG. 2 and formed so that only the hill portions did not transmit light was used. Any 10 points on the surface of a magnetic recording medium can be measured using STM and a stylus surface roughness meter.
As a result of measuring the height of the hill at each point, the height of the hill was 10 nm at all measurement points.

A schematic diagram of the cross-sectional structure in the radial direction of the magnetic recording medium of this example is shown in FIG. In this example, the area ratio of hills is 3.1% over the entire surface.

<Example 4> A magnetic recording medium was produced in the same manner as in Example 1, except that SiC was formed to a thickness of 20 nm by sputtering as a protective layer, and the etching time by ion milling to form hills was 20 seconds. . The height of the hill was measured at ten arbitrary points on the surface of the magnetic recording medium using a stylus type surface roughness meter, and the height of the hill was 10 nm at every measurement point.

<Example 5> As a protective layer, a C film (so-called 1-C) formed to a thickness of 20 nm by the plasma CVD method using a methane-hydrogen mixed gas as the raw material was used, and the etching time by ion milling to form hills was A magnetic recording medium was produced in the same manner as in Example 1, except that the heating time was 1 minute. The height of the hill was measured at ten arbitrary points on the surface of the magnetic recording medium using a stylus type surface roughness meter, and the height of the hill was 10 nm at every measurement point.

<Example 6> A 15 μm N1-P base film was formed on the surface of an aluminum alloy disk with an outer diameter of 5.25 inches by electroless plating, and the base film was polished to 10 μm and measured using a stylus type surface roughness meter. The average roughness (Ra) measured at 4 nm or less, the maximum roughness (R,
□) Mirror-finished to a thickness of 10 nm or less.

A positive resist (manufactured by Tokyo Ohka, 0FPR800) was applied to the N1-P surface of the substrate thus obtained to a thickness of approximately 0.5 μm, and the shape shown in Figure 1 was applied so that only the hill portions would not transmit light. After the formed photomask was brought into close contact with the mask and exposed, a mask pattern was formed on the surface of the C protective layer in the shape shown in FIG. 1, with resist remaining only in the hill portions.

The entire surface of this disk was irradiated with an argon ion beam for 30 seconds using an ion milling device to uniformly etch the areas where no mask pattern was formed, and then the mask pattern was removed using a resist removal solution. iP
Formed regularly arranged hills on the surface.

Next, a Cr intermediate layer of 0.2 μm thickness, a Co-Ni magnetic layer of 40 nm thickness, and a C protective layer of 20 nm thickness were formed on the above NiP surface by sputtering, and then a perfluoropolyether-based lubricant was applied as a lubricant layer. A magnetic recording medium was fabricated by coating to a thickness of about 5 nm. The height of the formed hill was measured using an STM (scanning tunneling microscope) at any 10 points on the surface of the magnetic recording medium.
As a result of measurement using R) and a stylus type surface roughness meter, the height of the hills was 10 nm at all measurement points.

FIG. 8 shows a schematic diagram of a cross section in the radial direction of the magnetic recording medium of this example.

<Example 7> As a substrate, the average roughness (R
a) A magnetic recording medium was prepared in the same manner as in Example 1, except that a tempered glass disk with an outer diameter of 5.25 inches and mirror-finished to have a roughness of 3 nm or less and a maximum roughness (Rwax) of 8 nm or less was used. was created. The height of the hill was measured at ten arbitrary points on the surface of the magnetic recording medium using a stylus type surface roughness meter, and the height of the hill was 10 nm at every measurement point.

Example 8 A magnetic recording medium was produced in the same manner as in Example 1, except that a photomask having concentric circular portions with a width of 1 μm and a pitch of 40 μm so as not to transmit light was used. Observing the surface of the magnetic recording medium with an electron microscope, @1 μm
It was confirmed that concentric hills with a pitch of 40 μm were formed over the entire surface. The height of the hill was measured at ten arbitrary points on the surface of the magnetic recording medium using an STM and a stylus surface roughness meter, and the height of the hill was 10 nm at all measurement points.

In this example, the area ratio of the hills is 2.5 over the entire surface.
%.

<Comparative Example 1> On the same substrate as in Example 1, an intermediate layer, a magnetic layer, and a protective layer were formed by sputtering in the same manner as in Example 1, and perfluoropolymer was directly applied as a lubricant layer on the protective layer. A magnetic recording medium was prepared by applying an ether-based lubricant to a thickness of about 5 nm.

<Comparative Example 2> While rotating the same substrate as in Example 1, it was polished by pressing a puff containing abrasive grains to form grooves along the circumferential direction. The surface of the substrate thus obtained had an average roughness (Ra) of 10 nm and a maximum roughness (Rmax) of 35 nm as measured using a stylus surface roughness meter.

An intermediate layer was formed on this substrate in the same manner as in Example 1.

A magnetic layer and a protective layer were formed by a sputtering method, and a perfluoroboethyl lubricant was directly applied onto the protective layer to a thickness of about 5 nm to prepare a magnetic recording medium.

Comparative Example 3 On the same substrate as in Example 1, a Cr intermediate layer with a thickness of 0.27 zm, a Co--Ni magnetic layer with a thickness of 40 nm, and a protective layer of C with a thickness of 40 nm were formed by sputtering. While rotating this disk, press a puff containing abrasive grains to
The protective layer was polished by about 10 nm to form grooves along the circumferential direction. A perfluoropolyether lubricant was applied as a lubricant layer to a thickness of about 5 nm on the surface of the disk thus obtained to produce a magnetic recording medium.

The surface of the magnetic recording medium thus obtained was measured with a stylus surface roughness meter to have an average roughness (Ra) of 10 nm and a maximum roughness (R
-a-) It was 30 nm.

Regarding the magnetic recording media obtained in the above Examples and Comparative Examples, a magnetic recording device was constructed using an Mn-Zn ferrite head, and C8S was achieved after approximately 30,000 C8S tests.
Within the area, we carried out (1) appearance inspection, (2) measurement of adsorption force and frictional force with the head, (2) contact count test between the head and the magnetic recording medium when the head was flying, and (2) recording and reproducing test. Note that the flying height of the head during steady rotation was 0.1 μm. The test results are shown in Table 1.

As shown in Table 1, in Comparative Example 1 in which no unevenness was formed, the initial adsorption force and frictional force were large, and the increase after csS was also large. For this reason, linear sliding marks are generated on the surface after C8S, and this damage causes significant deterioration of characteristics in contact count tests and recording/reproducing tests.

In Comparative Example 2, in which unevenness was formed on the substrate by a polishing method, the deterioration in characteristics after C8S was smaller than in Comparative Example 1, but there was still considerable deterioration in characteristics, and contact with the head and errors occurred even in the initial stage. . This is thought to be because in Comparative Example 2, local protrusions were easily generated during the polishing process, and it is believed that these areas caused pit-like peeling after C8S. Furthermore, in Comparative Example 2, since the unevenness is formed on the substrate, the magnetic layer formed thereon also has unevenness, and S
/N ratio is low.

In Comparative Example 3 in which unevenness was formed on the protective layer by a polishing method, as in Comparative Example 2, contact with the head and errors, which were thought to be caused by local protrusions during the polishing process, also occurred at the beginning. In Comparative Example 3, since the magnetic layer is almost flat, the initial S/N ratio is higher than in Comparative Example 2, but it is still insufficient.

This is because the flying stability of the head is not sufficient because the shape of the unevenness formed on the protective layer is non-uniform. Also C
The characteristic deterioration after 8S was also significant, and this is thought to be because the flying stability of the head was further impaired by the occurrence of peeled parts and the like.

On the other hand, the magnetic recording medium according to this example shows good characteristics before C8S, and the deterioration of characteristics after C8S is also small. This is because the uneven shape formed by regular pressure in this example does not have local protrusions, so the flying stability of the head is good.

In particular, an intermediate layer, a magnetic layer, and a protective layer are formed on a flat substrate, and the surface of the protective layer has hills arranged regularly so that fine dust attached to the head or magnetic recording medium can be quickly removed. When a lubricating layer is formed on the protective layer, the frictional force and adsorption force with the head are low.
It is possible to obtain a magnetic recording medium with small output fluctuations, guaranteed flying stability of the head, and little deterioration of characteristics over a long period of time.

Moreover, even when forming concentric regular hills, C8
The characteristic deterioration after S is smaller than that of the comparative example.

In the case of regular concentric hills, there is no effect to quickly remove fine dust attached to the head or magnetic recording medium, but the regularly arranged hills improve the flying stability of the head. Because it's better.

Since the head or the magnetic recording medium is less likely to wear out and the generation of wear powder itself is suppressed, deterioration in characteristics is reduced.

As described above, according to this embodiment, it is possible to obtain a magnetic recording medium that has low frictional force and adsorption force with the head, small output fluctuations, guarantees flying stability of the head, and has little characteristic deterioration over a long period of time. Can be done.

〔Effect of the invention〕

According to the present invention, the frictional force and adsorption force with the head are low, the output fluctuation is small, the flying stability of the head is guaranteed even at a low flying height, and the magnetic recording medium with small characteristic deterioration over a long period of time can be produced with high reproducibility. can be provided well.

[Brief explanation of the drawing]

1 and 2 are schematic diagrams showing the arrangement of hills formed on a protective layer or a non-magnetic substrate according to an embodiment of the present invention, and FIG. 3 shows the minimum flying peripheral speed of the head and the pressure area ratio. Figure 4 is a diagram showing the relationship between frictional force and groove depth. Figure 5 is a diagram showing the relationship between frictional force and groove depth.
The figures show magnetic disk devices, Figures 6, 7, and 8.
The figure is a schematic diagram of a cross-sectional structure in the radial direction of a magnetic recording medium according to an embodiment of the present invention. DESCRIPTION OF SYMBOLS 1... Aluminum alloy disc, 2... Base layer, 3...
...Intermediate layer, 4...Magnetic layer, 5...Protective layer, 6...
- Lubricating layer, 7... Formed hill, 11... Base, 1
2... Spindle, 13... Motor, 14... Magnetic recording medium (magnetic disk), 15... Magnetic head,
16... Carriage, A1 Mouth/4 $3 Hard $2 Eye 4 Parallel product ratio

Claims (1)

[Claims] 1. At least one magnetic disk having a magnetic layer and a surface protective layer on a substrate, facing the rotating magnetic disk with a small gap,
A magnetic disk device comprising: a magnetic head supported by a slider; rotating means for rotating the magnetic disk; and magnetic head positioning means for moving and positioning the magnetic head to a predetermined position on the magnetic disk. A magnetic disk device, characterized in that the surface of the magnetic disk is provided with the following (a) and (b). (a) A plurality of continuous or discontinuous grooves are provided, and a region surrounded by the plurality of grooves has a substantially flat surface. (b) In the convex formation region, the cumulative area ratio of the convex portions per unit area is 0.5% or more and 90% or less,
Further, the height of the convex portion is higher than 5 nm and lower than 40 nm, and has a substantially constant height within that range. 2. At least one magnetic disk having a magnetic layer and a surface protective layer on a substrate, the magnetic disk facing the rotating magnetic disk with a minute gap of 0.01 to 0.2 μm and supported by a slider. A magnetic disk device comprising: a head, a rotating means for rotating the magnetic disk, and a magnetic head positioning means for moving and positioning the magnetic head to a predetermined position on the magnetic disk, wherein the following is provided on the surface of the magnetic disk. A magnetic disk device comprising (a) and (b). (a) A plurality of continuous or discontinuous grooves are provided, and a region surrounded by the plurality of grooves has a substantially flat surface. (b) In the convex formation region, the cumulative area ratio of the convex portions per unit area is 0.5% or more and 90% or less,
Further, the height of the convex portion is higher than 5 nm and lower than 40 nm, and has a substantially constant height within that range. 3. A magnetic recording medium comprising at least a magnetic layer and a surface protective layer on a substrate made of a non-magnetic disk, characterized in that the surface protective layer comprises (a) and (b) according to claim 1. magnetic recording media. 4. In a magnetic recording medium comprising at least a magnetic layer and a surface protective layer on a substrate made of a non-magnetic disk, comprising (a) and (b) according to claim 1 on the non-magnetic disk. Features of magnetic recording media. 5. A magnetic recording medium having a hard underlayer, an intermediate layer, a magnetic layer, a protective layer, and a lubricating layer sequentially on an aluminum alloy substrate, wherein the convex portion according to claim 1 is formed on the surface of the hard underlayer. Features of magnetic recording media. 6. A magnetic recording medium having an intermediate layer, a magnetic layer, a protective layer, and a lubricating layer in this order on a non-magnetic substrate made of glass or ceramics, wherein the convex portion according to claim 1 is formed on the non-magnetic substrate. A magnetic recording medium characterized by: 7. The magnetic disk device according to claim 1, wherein the hill area ratio of the convex portion is changed from the outer circumference to the inner circumference of the disk. 8. A magnetic recording medium according to claim 5, wherein the convex portion according to claim 7 is formed on the surface of the hard underlayer. 9. A magnetic recording medium according to claim 6, characterized in that the convex portion according to claim 7 is formed on a nonmagnetic substrate. 10. The magnetic disk device according to claim 1, wherein the convex portion is formed on at least a surface of the magnetic disk used for positioning the magnetic head.