JP2953364B2 - Magnetic recording medium and substrate - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetic recording medium and a substrate, and more particularly to a magnetic recording medium such as a hard disk used in a magnetic disk drive and a substrate therefor. In particular, the present invention relates to a thin-film magnetic recording medium and a substrate thereof capable of simultaneously improving good CSS (contact start and stop) characteristics, improving sticking characteristics of the magnetic head to the medium surface, and lowering the flying height of the magnetic head.

[0002]

2. Description of the Related Art Normally, writing / reading of information to / from a hard disk is performed via a magnetic head, and at that time, the hard disk rotates at a high speed to float the magnetic head.

In order to improve magnetic characteristics, a hard disk is formed on a non-magnetic substrate surface or an underlayer made of a non-magnetic material such as NiP plating provided on the non-magnetic substrate, in a substantially concentric circular shape in the circumferential direction of the disk. (Hereinafter referred to as “mechanical texture”) is performed in which mechanical polishing is performed to leave processing marks.

[0004] With the recent increase in the amount of information and the demand for smaller and lighter devices, the linear recording density and track density have increased.
As the area per bit becomes smaller, the likelihood of scratches due to mechanical texture as in the prior art becomes an error when reading information increases. Therefore, a method has been proposed in which only the CSS area on the inner periphery of the disk is mechanically textured and the data recording area is kept as it is. In this case, the surface of the data recording area is higher than the height of the CSS area. There is a problem that the magnetic head crashes when seeking.

In addition, a method of forming a texture pattern by using a laser instead of such a mechanical texture has been proposed. Examples of texture by a laser are disclosed in U.S. Pat. Nos. 5,062,021 and 5,108,781 and the like. The NiP layer is locally melted by an Nd-YAG strong pulse laser beam. As shown in FIG. 6, a concave hole portion 6 formed by melting and a rim portion 7 having a diameter of 2.5 to 100 μm formed by solidifying the surrounding NiP by rising due to surface tension. An attempt has been made to improve the CSS characteristics with a magnetic head by forming a large number of crater-shaped irregularities and using an annular convex rim. However, this method does not drastically reduce the contact area with the lower surface of the magnetic head, and it is hard to say that the problem of sticking between the magnetic head and the disk is improved as compared with the mechanical texture.

[0006] A method of forming projections using photolithography has also been proposed. An example using photolithography can be found in the Japan Lubrication Society Tribology Proceedings (199
1-5, A-11) and (1992-10, B-6), in which the area ratio to the entire surface of the disc is 0.1.
The CSS test results of a magnetic disk in which 1 to 5% concentric protrusions are formed by photolithography are shown. However, in this method, since the tops of the projections are smooth, there is a disadvantage that the friction increases with the number of times of sliding of the magnetic head, and there is a problem that industrialization is not easy.

[0007]

As described above, in the CSS area of the magnetic recording medium, the area of the tip of the projection is reduced to eliminate sticking with the magnetic head, and the average surface height is reduced in the data recording area. When the magnetic head seeks between the data recording area and the CSS area, the fluctuation of the stable flying height of the magnetic head is small, causing head crash and instability in the space of the magnetic head. No magnetic recording medium is desired.

[0008]

The present invention has been made for such a magnetic recording medium for high-density recording. The first gist of the present invention is to provide a magnetic recording medium on a non-magnetic substrate through an underlayer if necessary. A magnetic recording medium having a magnetic layer, wherein a height of 1 to 100 nm is provided on the surface of the nonmagnetic substrate or underlayer on the side of the magnetic layer.
And the average value of the area of the figure surrounded by the contour lines at a height 1 nm lower than the tip of the protrusion is 2 μm ² or less,
The projection figure surrounded by contours is substantially semicircular or crescent-shaped in half the height of the projection height, surface 1 mm ²
A magnetic recording medium characterized by having 10 to 10 ⁸ pieces per piece.

A second feature of the present invention is that a magnetic layer comprising a non-magnetic substrate and an underlayer provided thereon if necessary.
A recording medium substrate, wherein the magnetic recording medium substrate has a magnetic property.
On the surface on which the layer is formed , the height is 1 to 100 nm, the average value of the area of a figure surrounded by contour lines at a height 1 nm lower than the tip of the projection is 2 μm ² or less, and the height of the projection is A substrate characterized in that a figure surrounded by contour lines at a height of ^２ has 10 to 10 ⁸ protrusions having a substantially half-moon shape or a crescent shape per 1 mm ^{2 of} the surface.

Hereinafter, the present invention will be described in detail. The magnetic recording medium and the substrate of the present invention have a height of 1 to 100 nm on the magnetic layer side surface of the nonmagnetic substrate or the underlayer, and an area of a figure surrounded by contour lines at a height 1 nm lower than the tip of the protrusion. The average value is 2 μm ² or less, and the figure surrounded by contour lines at half the height of the projections has 10 to 10 ⁸ projections per 1 mm ² on the surface, the projections being half-moon-shaped or crescent-shaped. It is characterized by being. When the non-magnetic substrate has a disk shape, a figure surrounded by contour lines at half the height of the protrusion is formed on the disk-shaped magnetic recording medium substrate.
Circumferential direction (hereinafter sometimes simply referred to as “circumferential direction”).
You. ) On a disk-shaped substrate for magnetic recording media that is longer than the length
Radial direction (hereinafter sometimes simply referred to as “radial direction”).
You. ) Is the shape of the protrusion whose length is longer.
It is characterized by having 10 to 10 ⁸ pieces per 1 mm ^{2 of} surface
And

The height of the projections is usually 1 to 100 nm, preferably 1 to 60 nm, and more preferably 5 to 40 nm.
Although the characteristics are good, it is sometimes difficult to lower the stable flying height of the magnetic head. If it is less than 1 nm, the substrate is buried in the fine irregularities inherent to the substrate, and it becomes difficult to obtain the desired effect. There is. In the present invention, the height of the protrusion refers to the height of the protrusion based on the center line of the roughness curve defined by JIS surface roughness (B0601-1982).

In the present invention, the average value of the area of a figure surrounded by contour lines at a height 1 nm lower than the top of the projection (hereinafter referred to as contour line area) is usually 2 μm ^2.
Or less, preferably, 1.0 .mu.m ² or less, more preferably 0.5 [mu] m ² or less, more preferably 0.2 [mu] m ²
It has the following values: If the contour area exceeds 2 μm ² , sticking between the magnetic head and the magnetic head is likely to occur, and it may be impossible to operate the CSS.

In the present invention, the shape of a figure surrounded by contour lines at half the height of a protrusion on a disk-shaped substrate is generally longer in the radial direction than in the circumferential direction. It is arranged in a long shape. Preferably, the ratio of the circumferential length to the radial length (circumferential length / radial length) of the figure surrounded by the contour line at half the height of the protrusion is equal to 0.1. It is desirably 2 to 0.7, particularly preferably 0.3 to 0.5.

Further, it is preferable that the figure surrounded by the contour lines at half the height of the projection is a half-moon or a crescent which is a half-moon or a crescent. In addition, the size of the contour line area at a position that is half the height of the protrusion is also
Depending on the lubricant used, CSS characteristics are affected, and usually, preferably 10 μm ² or less, more preferably 5 μm ² or less.

As described above, since the cross-sectional shape of the projection in the present invention has a steep half-moon or crescent shape, an effect of preventing the head from being attracted can be obtained. In particular, in a disk-shaped substrate, a figure surrounded by contour lines at a height of 突起 of the height of the protrusion has a shape in which the length in the radial direction is longer than the length in the circumferential direction, particularly a half-moon shape or a crescent shape. The protrusions are steeper than the relative running direction of the magnetic head and the medium, and are considered to exert the effect of preventing the magnetic head from being attracted to the surface of the medium by the lubricant.

The contour area and cross-sectional shape are as follows:
It is possible to measure with a surface shape measuring device by laser interference, for example, "ZYGO" manufactured by Zigo USA. A preferred embodiment of the present invention is a magnetic recording medium in which protrusions are present only in an area where the magnetic head performs CSS (CSS area), and are not present in the data recording area. By adopting such a configuration, a light texture in the circumferential direction for the purpose of only the orientation of the magnetic layer can be adopted in the data recording area, and the surface can be made smoother. Therefore, it is possible to reduce errors caused by scratches due to mechanical texture for improving CSS as in the related art.

In a further preferred embodiment, the protrusions are present only in the region where the magnetic head performs CSS and are not present in the data recording region, and the heights of the protrusions on the side close to the data recording region or the heights of all protrusions Is decreasing toward the data recording area. By reducing the protrusion height toward the data recording area, the magnetic head can be stably sought from the data recording area in the CSS area or in the opposite direction.

Further, the protrusion may be present not only in the CSS area but also in the data recording area. With this,
Even when the magnetic head stops in the data recording area due to a trouble or the like, it is possible to prevent the magnetic head from being attracted to the medium surface. In this case, the protrusion height of the data recording area is preferably lower than the protrusion height of the CSS area, and the protrusion density of the data recording area is preferably lower than the protrusion density of the CSS area. By making the projection height and the projection density of the data recording area smaller than those of the CSS area, the flying height of the magnetic head in the data recording area can be reduced.

Normally, the CSS in the data recording area is
As long as it can be performed about 100 times, the projection height of the data recording area is usually 以下 or less of the projection height of the CSS area, and the projection density of the data recording area is 1/1 of the projection density of the CSS area.
It is good to be about 0 to 1/10 ⁴ . Also in this case, the protrusion on the side near the data recording area in the CSS area,
Alternatively, it is preferable that the heights of all protrusions decrease toward the data recording area.

A preferred method for producing the magnetic recording medium of the present invention is to rotate a magnetic recording medium substrate provided with an underlayer such as NiP on a non-magnetic substrate such as an Al substrate or on a non-magnetic substrate. Along its circumference on its surface,
A method of forming projections on the surface by irradiating an energy ray whose output is controlled with high accuracy, and the like can be given. Examples of the energy beam include a pulse laser, an electron beam, an X-ray, and the like. Among them, it is preferable to use a pulse laser. Hereinafter, the present invention will be described using a pulse laser as an example.

In the present invention, the formation mechanism of the projections has not yet been sufficiently elucidated, but is considered as follows. FIG. 3 is a conceptual diagram showing an expected generation mechanism of a protrusion. FIG.
In (a), the spot portion 5 irradiated with the pulse laser 3 and locally heated is partially melted, and the melted portion is moved by the rotation of the substrate (the direction is indicated by an arrow) or the scanning of the laser beam. As shown in FIG. 3 (b), the temperature of the portion first hit by the beam decreases thereafter, so that a temperature gradient occurs in the melted portion. In general, the surface tension of the molten liquid on the low-temperature side is higher.Therefore, due to the difference in the surface tension, the part that is first irradiated by the beam and melts, and then cools down, takes in the liquid from the molten part later. Excitement.
Therefore, as shown in FIG. 3C, a concave portion is formed in the last melted portion, and a concave portion is provided at a rear portion of the protrusion in the scanning direction of the laser beam. In other words, a vertical cross-sectional shape that passes through the center of the projection and is parallel to the scanning direction of the laser beam has a concave portion on one side of the bottom of the projection.

If the pulse width is narrow, small protrusions may be formed in the scanning direction so as not to particularly affect the CSS characteristics, following the concave portions at the rear of the protrusions. It should be noted that, in the present invention, a projection whose contour in a radial direction is longer than that in a circumferential direction, particularly a projection surrounded by contour lines at a height of 突起 of the projection height, which is characteristic of the present invention, in particular, In order to form a half-moon or crescent-shaped projection, it is necessary to shorten the irradiation time of the pulse laser. Normally, the scanning distance on the substrate within the irradiation time is desirably within twice the laser spot diameter.

When a pulse laser beam is scanned on a non-magnetic substrate such as an aluminum substrate, a glass substrate, or a substrate on which an NiP layer, a Cr layer, or the like is provided as an underlayer, the above-described characteristic shape is obtained. It becomes a projection. In the present invention, the scanning direction of the laser beam means not only the direction in which the laser beam scans on the stationary substrate, but also the direction of rotation of the disk when the laser beam is kept stationary and the substrate is irradiated while rotating. Is also shown.

Depending on conditions such as the scanning of the laser beam or the rotation of the substrate is slow, or the power of the laser beam is large, a recess may be formed around the bottom of the projection due to thermal contraction. The locally heated spot expands and the area around it cools and is hard to deform, so the expanded part is immediately cooled by the outside air and remains as a protrusion, and the periphery of the protrusion can be dented by thermal contraction. Conceivable. Further, the tops of the projections of the present invention are not flat but have an appropriate curvature.

The aforementioned US Pat. No. 5,062,021,
No. 5,108,781, the laser beam irradiation range is wide and the laser output is 1.5 W.
Because of such a large output, the melting range of NiP is wide, and the center of the melted liquid surface does not rise and becomes a crater shape.

On the other hand, according to the present invention, the laser beam is narrowed down to a narrow range, and the projections are controlled accurately under the condition that the output is low. Therefore, the melting range is narrow and the center of the melted liquid surface is convex. The rising of the beam causes a temperature difference in the liquid due to the scanning of the beam, and the shape of the liquid surface changes in a complicated manner.
Therefore, the tip of the projection becomes steeper depending on the conditions, and also has a characteristic projection shape when solidified. Therefore, the area of the tip is also very small, and a preferable projection for CSS is formed.

The height of the projections can be freely controlled by adjusting the laser spot diameter, intensity, average irradiation time, and linear velocity of the disk.
It can be controlled freely by adjusting the number of protrusions per rotation, the irradiation interval of the pulse laser in the radial direction, and the conditions for controlling the height of the protrusions. In the present invention, the preferable laser intensity is 20 to 500 mW, particularly preferably 200 to 500 mW, and the average irradiation time is preferably 0.1 to 5 μsec, particularly preferably 0.1 to 1 μm.
sec, the laser spot diameter is preferably 0.5 to 2 μm.
m, particularly preferably 0.8 to 1.5 μm, and the linear velocity of the substrate is preferably 1 to 10 m / sec, particularly preferably 1 to 10 m / sec.
4 m / sec. Here, the average irradiation time of the laser indicates the time during which the laser is applied to the substrate or the underlayer surface to form one projection.

In order to change the irradiation area of the laser beam, it is usually sufficient to change the aperture ratio of the objective lens. For example, by using an objective lens having an aperture ratio of 0.1 to 0.95, the beam irradiation diameter can be reduced. It can be controlled to about 0.7 to 6 μm. In the present invention, an aluminum alloy plate or a glass substrate is usually used as the nonmagnetic substrate, but a metal substrate such as copper or titanium, a ceramic substrate, a resin substrate, or the like can also be used. The underlayer is a layer made of a nonmagnetic material, preferably a NiP alloy layer, and is usually formed by electroless plating or sputtering. Usually, a Cr layer is formed thereon, but projections can be formed on the Cr layer.
The thickness of the underlayer is important in view of the relationship between heat generation by laser irradiation and heat dissipation by heat conduction, and is preferably 50 to 2,000.
0 nm, particularly preferably 100 to 15,000 nm.

It is preferable that an intermediate layer such as a Cr layer or a Cu layer is provided on the underlayer between the magnetic layer and the intermediate layer.
0 nm. The magnetic layer provided on the underlayer or the intermediate layer is usually made of Co-P, Co-Ni-P, Co-Ni-C.
r, Co-Ni-Pt, Co-Cr-Ta, Co-Cr
-Pt, a Co-Cr-Ta-Pt-based alloy or the like is formed by forming a ferromagnetic alloy thin film by a method such as electroless plating, electroplating, sputtering, and vapor deposition. It is about 70 nm.

A protective layer is provided on the magnetic layer.
As the protective layer, a carbon film, a hydrogenated carbon film, a carbide film such as TiC or SiC, a Si film by a method such as vapor deposition, sputtering, plasma CVD, ion plating, or a wet method.
A nitride film such as N or TiN, or an oxide film such as SiO, Al ₂ O ₃ or ZrO is formed. Of these, a carbon film and a hydrogenated carbon film are particularly preferred. Further, a lubricant layer is usually provided on the protective layer.

[0031]

Next, the present invention will be described in more detail with reference to examples.
However, the present invention is not limited to the following
It is not limited by the examples. Examples 1 to 5, Comparative Examples 1 to 5  Film on a disk-shaped aluminum alloy substrate with a diameter of 95 mm
After applying NiP plating with a thickness of 10-20 μm, surface roughness
The surface was polished so that Ra was 1 nm or less.

Next, the substrate is irradiated with an argon pulse laser whose intensity is precisely controlled as shown in Table 1 on the substrate under the conditions shown in Table 1 to form projections. Obtained. FIG. 1 is a diagram showing the results of observing the surface shape of the NiP layer of the substrate obtained in Example 1 with a surface shape measuring device (“ZYGO” manufactured by Zigo Corporation, USA) using laser interference. FIG. 2 is a photograph of a halftone image in which the projections shown in FIG. 1 are observed from above (horizontal direction in the drawing) by the same device, and the results are displayed on a display in different colors according to the height. The shape shows a cross-sectional shape horizontal to the substrate surface of the protrusion. From FIG. 2, it can be seen that the shape of the cross section of the protrusion horizontal to the substrate surface is a crescent shape.

That is, the projection of the present invention has a characteristic shape as shown in FIGS. 1 and 2, and the top of the isolated projection is not flat but has an appropriate curvature. Next, on the NiP underlayer of the substrate by sputtering,
A Cr intermediate layer (film thickness 100 nm), a Co—Cr—Ta alloy magnetic film (film thickness 50 nm) and a carbon protective film (film thickness 2
0 nm), and then a fluorinated liquid lubricant (“DOL-200” manufactured by Monte Edison Co., Ltd.) by an immersion method.
0 ") was applied to a thickness of 2 nm to produce a magnetic recording medium.

In Comparative Example 5, a magnetic disk was manufactured by the same process as in the Example, except that an Al alloy substrate having a texture having a roughness of about 2 nm was used by a conventional mechanical texture method. did. 4 and 5 show the protrusion shape of Comparative Example 4, and the horizontal cross section of the protrusion has an elliptical shape. FIG. 4 is a view showing the results of observing the surface shape of the NiP layer of the substrate obtained in Comparative Example 4 with a surface shape measuring device (“ZYGO” manufactured by Zigo Corporation, USA) using laser interference. FIG. 5 is a photograph of a halftone image in which the projection shown in FIG. 4 is observed from above (horizontal direction in the drawing) by the same apparatus, and the result is displayed on a display in different colors depending on the height. The shape shows a cross-sectional shape horizontal to the substrate surface of the protrusion.
From FIG. 5, it can be seen that the shape of the cross section of the protrusion horizontal to the substrate surface is elliptical.

Table 1 shows the conditions for forming the projections and the measurement results (linear velocity of the substrate, laser intensity, average irradiation time of the laser, average projection line) in Examples 1 to 5 and Comparative Examples 2 to 4. Density (circumferential / radial direction), average projection height, area of figure enclosed by contours at a height 1 nm lower than the tip of the projection (contour area), enclosed by contours at half height of projection Shape (projection horizontal cross-sectional shape) of the drawn figure. The objective lens used for laser focusing had an aperture ratio NA of 0.6. In addition,
The spot diameter at which 84% of the energy is concentrated is 1.22
× λ / NA.

[0036]

[Table 1]

Table 2 shows the room temperature of these magnetic disks,
The static friction coefficient (initial stiction) before the CSS test at normal humidity and the friction force after 20,000 times of CSS are shown. CSS
The test was head flying height 2.5μ inch, loadgram 6
A gf thin film head (slider material: Al ₂ O ₃ TiC) was used. The stable flying height of the CSS region was 1.2 to 1.6 μ inch except for Comparative Example 3. Table 3 shows the CSS test results of the magnetic disks obtained in Example 1 and Comparative Example 4 at 30 ° C. and 80% humidity.

[0038]

[Table 2]

[0039]

[Table 3]

As is clear from Tables 2 and 3, the magnetic recording medium according to the present invention has extremely low friction during CSS and has excellent performance continuity. In addition, the CSS characteristics slightly change depending on the shape of the protrusion. For example, an elliptical protrusion long in the head running direction as in Comparative Example 4 has good CSS characteristics under normal temperature and normal humidity conditions. However, under conditions of high temperature and high humidity, the characteristics deteriorate as the number of times of CSS increases. On the other hand, the crescent-shaped or half-moon-shaped projections according to the present invention, which are steep in the head running direction, have their characteristics degraded slowly even under high temperature and high humidity.

[0041]

According to the present invention, a surface shape is formed on the surface of a substrate or an underlayer in which the shape and height of the protrusion, the cross-sectional area in the horizontal direction at the tip portion, the region where the protrusion exists, and the density are controlled. Therefore, the contact area between the lower surface of the magnetic head and the surface of the magnetic recording medium is small, friction during CSS becomes extremely small, and sticking of the magnetic head to the medium surface does not occur at all.

Also, if the density of the protrusions in the circumferential direction is increased and the CSS characteristics are not significantly deteriorated even if the density of the protrusions in the radial direction is reduced, there is an advantage that the time required for forming the protrusions can be reduced. Further, when such protrusions are formed only in the CSS area, the average surface height hardly changes. Therefore, when the magnetic head is sought between the data recording area and the CSS area, the stable flying height of the magnetic head is reduced. There is almost no fluctuation, and no head crash or instability in the head space occurs. Further, since the height and density of the projections can be controlled as they approach the data recording area, the seek between the data recording area and the CSS area of the magnetic head can be performed extremely smoothly.

In this case, in the data recording area, it is not necessary to make a surface scratch due to the mechanical texture for the purpose of improving CSS as in the prior art, so that the flying height of the magnetic head can be reduced, and Since data errors are also reduced, high-density magnetic recording media can be manufactured, which is of great industrial significance.

[Brief description of the drawings]

FIG. 1 is a view showing the shapes of protrusions on the surface of a NiP substrate of a substrate obtained in Example 1 observed by a surface shape measuring apparatus.

FIG. 2 shows a projection shown in FIG.
5 is a photograph of a halftone image in which the result is observed on the display in different colors depending on the height.

FIG. 3 is a conceptual diagram showing an expected generation mechanism of a projection according to the present invention.

FIG. 4 is a view showing the shape of protrusions on the surface of a NiP substrate of a substrate obtained in Comparative Example 4 observed by a surface shape measuring apparatus.

FIG. 5 is a perspective view of the projection shown in FIG.
5 is a photograph of a halftone image in which the result is observed on the display in different colors depending on the height.

FIG. 6 is a perspective view showing the shape of the surface of a magnetic recording medium according to a conventional method.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Projection 2 Depression 3 Pulse laser 4 Non-magnetic substrate 5 Spot part 6 Concave hole 7 Rim

──────────────────────────────────────────────────続 き Continuation of the front page (72) Inventor Junichi Kozu 1000, Kamoshida-cho, Aoba-ku, Yokohama-shi, Kanagawa Prefecture Mitsubishi Chemical Corporation Yokohama Research Laboratory (56) References JP-A-8-30963 (JP, A) Hei 7-182655 (JP, A) (58) Fields investigated (Int. Cl. ⁶ , DB name) G11B 5/82 G11B 5/84

Claims (16)

(57) [Claims] 1. A magnetic recording medium having a magnetic layer on a non-magnetic substrate, if necessary, with an underlayer interposed therebetween, wherein the height of the magnetic recording medium is 1 to 100 nm on the magnetic layer side surface of the non-magnetic substrate or the underlayer.
And the average value of the area of the figure surrounded by the contour lines at a height 1 nm lower than the tip of the protrusion is 2 μm ² or less,
The projection figure surrounded by contours is substantially semicircular or crescent-shaped in half the height of the projection height, surface 1 mm ²
A magnetic recording medium comprising 10 to 10 ⁸ pieces. 2. A disc-shaped magnetic recording medium having a magnetic layer on a disc-shaped non-magnetic substrate, if necessary, with an underlayer interposed therebetween, wherein the height of the disc is higher than that of the non-magnetic substrate or the underlayer. Is 1 to 100 nm, and the average value of the area of a figure surrounded by contour lines at a height 1 nm lower than the tip of the protrusion is 2 μm.
² or less, and a figure surrounded by contour lines at half the height of the protrusion has a shape in which the length in the radial direction is longer than the length in the circumferential direction of the disk-shaped magnetic recording medium. A magnetic recording medium comprising 10 to 10 ⁸ per 1 mm ^{2 of} the surface. 3. The magnetic recording medium according to claim 2, wherein the figure surrounded by contour lines at half the height of the projection is a half-moon or a crescent. 4. A projection having a recess around the bottom of the projection.
4. The magnetic recording medium according to any one of items 3 to 3. 5. The magnetic recording medium according to claim 1, wherein the protrusion is present only in an area (CSS area) where the magnetic head performs CSS (contact start and stop). 6. A projection, magnetic recording medium according to any one of claims 1 to 4 is present in the C SS area and a data recording area. 7. The magnetic recording medium according to claim 6, wherein the protrusion height of the data recording area is lower than the protrusion height of the CSS area. 8. The magnetic recording medium according to claim 6, wherein the protrusion density of the data recording area is smaller than the protrusion density of the CSS area. 9. The magnetic recording medium according to claim 1, wherein a protrusion height of the CSS area near the data recording area is lower than an average value of all protrusion heights of the CSS area. 10. The magnetic recording medium according to claim 1, wherein the height of the protrusion in the CSS area gradually decreases toward the data recording area. 11. The magnetic recording medium according to claim 1, wherein the protrusion density in the radial direction of the CSS region is lower than the protrusion density in the circumferential direction. 12. The magnetic recording medium according to claim 1, wherein the projection is formed by irradiating an energy beam. 13. The magnetic recording medium according to claim 12, wherein the vertical cross-sectional shape passing through the center of the projection and parallel to the scanning direction of the irradiation energy beam has a recess near one side of the bottom of the projection. 14.Non-magnetic substrateAnd if necessaryin additionSetting
Base layerFor magnetic recording mediasubstrateAt,
Surface of the magnetic recording medium substrate on which the magnetic layer is formed
The height is 1 to 100 nm and 1 n from the tip of the protrusion.
The average of the area of the figure enclosed by the contour lines at m lower height
2 μm^TwoBelow, and the height of the projection
The figure enclosed by the contour lines is roughly half-moon-shaped or crescent-shaped.
Projections on the surface 1 mm^Two10 to 10⁸Have
A substrate characterized by the following. 15. A non-magnetic substrate, a disk-shaped magnetic recording medium substrate comprised of underlayer eclipsed set <br/> thereon as required
The side of the magnetic recording medium substrate on which the magnetic layer is formed
The surface has a height of 1 to 100 nm, the average value of the area of a figure surrounded by contour lines at a height 1 nm lower than the tip of the projection is 2 μm ² or less, and the height is half the height of the projection. Of the disk-shaped magnetic recording medium
A substrate for a magnetic recording medium, comprising 10 to 10 ⁸ protrusions per 1 mm ^{2 of} the surface of the body substrate, the protrusions being longer in a radial direction than in a circumferential direction. . 16. The figure enclosed by contour lines at half the height of the projection is a half-moon or crescent.
6. The substrate for a magnetic recording medium according to 5.