JPH1186281A - Magnetic recording medium and manufacture thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enable using of a highly reliable glass substrate with a lower floating which uses an inexpensive electron beam generator to set the diameter of irradiation above a specified micron unit during the irradiation. SOLUTION: A Cr layer is accumulated by 50 nm on a base body made of soda lime by sputtering in an Ar atmosphere at a vacuum pressure of 1×10<-3> Torr to use a substrate 1 for a magnetic disc. Then, it is irradiated with an electron beam for 60 sec. under conditions of a vacuum pressure of 1×10<-3> Torr, acceleration voltage of 10 kV and a beam diameter of 1 micron. A spindle-shaped protrusion with the diameter of 1 micron at a point 2 nm below the topmost point thereof is formed on the surface of the substrate 1 at a height of 100 nm. A ground film 2 for controlling a magnetic film, a magnetic film 3 comprising a main component element Co, a protective film 4 and a perfluoropolyester based lubricating film 5 are formed to obtain a magnetic recording medium 10.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a magnetic recording medium, and more particularly, to a magnetic recording medium having high reliability and low flying height. Further, the present invention provides a method for forming projections on a magnetic recording medium having a non-magnetic substrate such as glass or ceramics at low cost and with high accuracy.

[0002]

2. Description of the Related Art Conventionally, a surface of a non-magnetic substrate constituting a magnetic disk medium is machined to obtain a texture and a magnetic disk medium for the purpose of preventing attraction between the magnetic disk medium and a head or improving magnetic characteristics of the magnetic disk medium. It is general to form a so-called uneven shape.

[0003] Also, Journal of Applied Physics (Journal of April 15, 1991)
of Applied Physics: Vol. 6
9. No. (Pages 8.5745 to 5747), a method of forming projections on a non-magnetic substrate using a laser has also been realized.

[0004] However, when the substrate is made of metal, the above-mentioned processing of the substrate surface is possible. However, when tempered glass, which has been used recently, is used as the substrate, neither mechanical processing nor processing using a laser is impossible. It is possible.

Therefore, as described in Japanese Patent Application Laid-Open No. H8-102033, there is an example in which a method of forming projections by forming a predetermined film in a vacuum on a glass substrate without using mechanical processing is used. is there. In addition, Japanese Patent Application Laid-Open No. 7-16103
As described in No. 2, a method of applying particles to a protective film has also been proposed. Also, in a projection detecting head calibration disk having a small number of projections, Japanese Patent Laid-Open No. 6-20268 is disclosed.
As described in Japanese Patent Application Laid-Open No. H11-260, there has been proposed a method of forming a mask having an arbitrary shape by using a photolithography technique and forming a projection using the mask.

[0006]

In any case, manufacturing a magnetic recording medium using a glass substrate having both high reliability and low flying height requires a great increase in price compared to the current state. However, it is difficult to provide an inexpensive magnetic recording medium because its forming technology requires a high forming technology. In particular, when a projection is added to only a part of the surface of the magnetic recording medium, a high technology is required.

Further, in a disk for calibrating a head for detecting a protrusion having a small number of protrusions, a mask is designed only for forming the protrusion. If the required shape changes, it is necessary to redesign the mask. Further, the size is limited, and it is difficult to form a projection having a diameter of 1 micron or less.

[0008]

Therefore, in the present invention, the above problem is easily avoided by forming a projection on the substrate surface using an electron beam. The irradiation diameter of the electron beam used in the present invention can be arbitrarily set to 0.1 μm or more using an inexpensive electron beam generator. In addition, since the acceleration voltage at the time of irradiation can be arbitrarily set, a projection having a desired size and height can be formed by selecting a setting condition.

The material to be irradiated can be freely selected by using an electron beam, and a projection can be easily formed on any substrate material via an extremely thin metal layer or non-metal layer. can do. In addition, since protrusions can be formed after film deposition not only on the substrate but also on any layer of the medium constituting layer, the protrusions can be formed on layers that require protrusions.

Further, not only the magnetic recording medium but also the disk for calibrating the flying height of the head for detecting the protrusion can be formed with a fine diameter and the required height at an arbitrary position with high precision. In addition, since disks of the same quality can be easily manufactured, a plurality of disks having projections with good projection reproducibility can be prepared.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail.

FIG. 1 is a diagram showing a magnetic recording medium according to an embodiment of the present invention. Diameter 65 made of soda lime
mm, plate thickness 0.635 mm, average center line roughness Ra 0.8
A substrate made of a glass plate having a thickness of nm was chemically strengthened and washed. On this substrate, A at a vacuum pressure of 1 × 10 −3 Torr was applied.
A Cr layer was deposited to a thickness of 50 nm by sputtering in an r atmosphere and used as a magnetic disk substrate 1.

Next, an electron beam was irradiated for 60 seconds under the conditions of a vacuum pressure of 1 × 10 −3 Torr, an acceleration voltage of 10 kV, and a beam diameter of 1 μm. At this time, as shown in FIG. 3, spindle-shaped protrusions having a height of 100 nm and a diameter of 1 μm at a point 2 nm below the protrusion top were formed on the surface of the substrate 1.
Further, a base film 2 for controlling the magnetic film, a magnetic film 3 made of Co as a main component element, a protective film 4 and a perfluoropolyether-based lubricating film 5 are sequentially formed.
0 was set.

Next, as the conditions for irradiating the electron beam, the projections are formed by changing the time while keeping the vacuum pressure, the acceleration voltage and the beam diameter constant, and the height of the projections formed under each condition is measured. did. The result is shown in FIG. It can be seen that the projection height increases as the irradiation time of the electron beam increases.

Similarly, as the conditions for irradiating the electron beam, the beam diameter and the electron beam irradiation time are kept constant, the acceleration voltage is changed to form the projection, and the height of the projection formed under each condition is measured. In this case, the height of the protrusion increased with an increase in the acceleration voltage. In addition, as conditions for irradiating the electron beam,
When the beam diameter was changed while keeping the acceleration voltage and the irradiation time constant, the diameter of the protrusion increased as the beam diameter increased, and the height decreased.

Further, a vacuum pressure of 1 × is applied to the substrate 1 provided with the Cr film.
An electron beam was irradiated for 0.5 seconds under the conditions of 10-3 Torr, an acceleration voltage of 30 kV, and a beam diameter of 1 micron to form a projection 11 having a height of 15 nm on the Cr film. Here, the protrusion density 1
The protrusions 11 were formed by intermittently irradiating an electron beam while synchronizing with the pitch interval time while intermittently rotating the substrate 1 at a constant pitch so as to obtain 000 / mm 2. As a result,
The shape is a spindle shape, the diameter at a point 2 nm below the apex of the protrusion is 1 micron, and the height of the protrusion is an atomic force microscope (AF).
As a result of the measurement in M), a uniform projection 21 having an average of 15.2 nm and a standard deviation of 0.23 nm could be formed.

Further, on the substrate 1 on which the projections 11 were formed, a CoCrTa film was formed as a magnetic film 3 to a thickness of 30 nm, and a protective film 4 was formed from a carbon to which 10% of hydrogen was added to a thickness of 15 nm by sputtering. Then, a 2 nm lubricating film 5 was formed thereon by applying a perfluoropolyether-based lubricating film to obtain a magnetic recording medium.

In order to investigate the head flying characteristics of the magnetic recording medium, a flying magnetic head having an acoustic emission (AE) sensor mounted thereon, having a length of 2 mm, a width of 1.7 mm, and a rail surface formed on a flying surface is projected. A projection detection tester was installed as a detection head, and the projection detection conditions were set to detect a projection height of 25 nm. The peripheral speed of the head at the time of detecting the protrusion was set to be constant so that the change in the flying height at the peripheral position at the measurement position of the manufactured magnetic recording medium was not affected. When the protrusion of the magnetic recording medium was detected, no protrusion was detected at a flying height of the protrusion detection head of 25 nm.

Further, in order to investigate the attraction characteristics between the present magnetic recording medium and the magnetic head, a floating magnetic head having a length of 2 mm and a width of 1.7 mm was floated on the present magnetic recording medium. The spring load supporting the magnetic head at this time was set to 3 gf. Using this magnetic head, the attraction characteristics with the present magnetic recording medium were measured. The maximum frictional force was 1.2 gf at maximum, and the average dynamic frictional force was 0.8 gf.
On the other hand, for comparison, when the maximum frictional force and the dynamic frictional force were measured for magnetic recording media having the same configuration without protrusions, the maximum values were 80 gf and 65 gf, respectively. Therefore, it is possible to obtain a highly reliable magnetic recording medium which is excellent in abrasion resistance with the magnetic head even when the flying height is reduced, and which can reduce the attraction force.

Next, a diameter of 65 m made of soda lime
m, plate thickness 0.635 mm, average center line roughness Ra 0.8 n
m at a vacuum pressure of 3 × 10 −3 Torr on a magnetic disk glass substrate that has been chemically strengthened and washed on a glass plate of
A 5 nm Cr film was deposited by sputtering in an r atmosphere.

Further, the substrate is vacuumed at a pressure of 1 × 10 −3 To.
An electron beam was irradiated for 0.7 seconds under the conditions of rr, an acceleration voltage of 10 kV, and a beam diameter of 1 micron to form a projection having a height of 20 nm. In order to confirm that the projections were formed by grinding the glass substrate simultaneously with the Cr film by the irradiated electron beam, the Cr film was completely removed with hydrochloric acid, and the projection height on the glass substrate was confirmed. . At this time, it was confirmed that projections having an average height of 18 nm were formed on the glass substrate. Here, the projections were formed by intermittently irradiating an electron beam while synchronizing with the pitch interval time while intermittently rotating the substrate at a constant pitch so that the projection density became 3000 / mm 2. At this time, the height of the projection is 19.8 nm on average,
The standard deviation was 0.6 nm. Further, it was confirmed again that protrusions were formed on the glass substrate. After that, a Cr film of 40 nm and CoCrT
The film a was formed to a thickness of 30 nm, and a protective film formed of carbon to which 10% of hydrogen was added was formed to a thickness of 15 nm. Further, a 2 nm perfluoropolyether-based lubricating film was applied thereon. The projection height of the outermost surface of the magnetic recording medium was 16.5 nm, and the standard deviation was 0.7 nm.

In the present magnetic recording medium, the length is 2 mm,
Using a floating magnetic head having a 1.7 mm wide floating surface with rail processing applied thereto, adsorption characteristics with the head were investigated. The spring load supporting the magnetic head at this time was set to 3 gf. When the suction characteristics were measured using this head, the maximum frictional force was 1.3 gf at maximum, and the average dynamic frictional force was 0.9 g.
f. As a result, it can be seen that a magnetic recording medium having high reliability and excellent low flying characteristics can be obtained.

On a crystallized glass substrate having an average center line roughness Ra of 0.8 nm, a 50 nm Cr film is formed as a base film, a 20 nm Cr base film and a 40 nm CoCrTa magnetic film are sequentially formed. A projection of 20 nm was formed on the surface of the magnetic film. Here, vacuum pressure 1 × 1
An electron beam is irradiated for 0.1 second under the conditions of 0-3 Torr, an acceleration voltage of 10 kV, and a beam diameter of 1 micron, and the substrate has a radius of 15 mm.
100000 protrusions / m in the area of 17 mm to 17 mm
They were evenly arranged at m2. Further, when all the deposited films were removed with hydrochloric acid in order to confirm whether or not projections were formed on the glass substrate, no projections were formed on the glass substrate.

Further, a carbon protective film containing 5% hydrogen was
After forming a 0 nm film, a 2.5 nm lubricating film was applied and formed. At this time, the projection height after formation of all the films was 18.3 nm on average by an atomic force microscope (AFM), and the standard deviation was 0.4 nm.

Also in the present magnetic recording medium, the head flying height 2
When the protrusion was detected at 8 nm, no protrusion detection signal was generated due to the main protrusion.

Further, for a region of a radius of 15 mm to 17 mm of the magnetic recording medium, the length is 2 mm and the width is 1.7 mm.
The maximum frictional force and the dynamic frictional force were measured using a floating type head with a spring load of 3.5 gf.
f, 1.2 gf. At this time, a radius of 15 mm
The maximum frictional force and the dynamic frictional force other than the area of 7 mm were 90 gf and 75 gf at the maximum, respectively. Thus, even when a plurality of thin films are formed on a substrate and then projections are formed on the thin film formed by irradiating an electron beam, high levitation can be achieved with high reliability.

Next, a diameter of 65 mm and a thickness of 0.635 m
m, a 20 nm thick Cr metal film was deposited on a tempered glass substrate having an average center line roughness Ra of 0.8 nm, and then a vacuum pressure of 1 × 10 −3.
An electron beam was irradiated for 0.5 seconds under the conditions of Torr, an acceleration voltage of 30 kV, and a beam diameter of 3 μm.
One piece was produced at each position of m. Further, after depositing a Cr underlayer by 20 nm by a sputtering method, a 10 nm hydrogen-added 20% carbon protective film was deposited as a protective film by a sputtering method. Thereafter, a 1.5 nm perfluoropolyether-based lubricating film was applied. When the heights of the protrusions at the respective positions of the substrate radii of 15 mm, 23 mm, and 30 mm were measured by an atomic force microscope (AFM), they were 23 nm, 22.5 nm, and 23.4 nm, respectively.
Met.

The magnetic recording medium of the present invention has a protrusion detection flying height of 20 n.
The protrusions were detected using a protrusion detection head with acoustic emission set to m. At this time, each protrusion was detected. Further, in the repeated measurement, protrusions could be detected with a probability of 90% or more. Further, in order to investigate the durability of the projection, the head was caused to collide with the projection at a fixed radius of 10000 times at a position having a radius of 15 mm.

Further, one protrusion is formed with a radius of 1 by the same manufacturing method.
Zero protrusion detection head calibration disks arranged at the positions of 5 mm, 23 mm, and 30 mm were manufactured. When using the same to detect protrusions with the same protrusion detection head,
The detection accuracy was 90% or more, and an examination of the projection height after the detection of the projections revealed that the average of the projection heights was 23.1 nm and the standard deviation was 0.53 nm.

As described above, the projection detecting head calibration disk having the projections manufactured by the present manufacturing method for confirming the flying height of the projection detecting head is high in accuracy and excellent in durability. all right.

The projection diameter can be formed to any size from 0.1 μm, and the shape can be any shape such as a prism or a cone.

In the above-described embodiment, an example in which glass is used as a substrate material has been described. However, glass and ceramic such as soda lime glass, quartz glass, crystallized glass and the like may be used. Further, the same effect can be obtained with a non-magnetic metal substrate plated with Ni-P or the like. In this case, it is important that the maximum surface roughness of the substrate is smaller than the projection formation height.

Further, with regard to the arrangement of the projections, it is possible to provide a magnetic recording medium having high reliability and low flying height by setting the projection shape, projection height, and projection density required for the magnetic recording medium. Can be. Further, a film on which protrusions are further formed can be arranged on the film on which protrusions are formed.

Further, as the film deposited on the substrate, any material can be used as long as it is an appropriate material group other than those described in this embodiment.

[0035]

According to the present invention, a magnetic recording medium having projections formed by irradiating an electron beam onto the surface of a substrate or a film formed on the substrate and a disk for calibrating a projection detection head have high reliability even at low flying height. be able to. Further, the manufacturing method according to the present invention is effective for transparent materials such as glass, regardless of the material of the substrate, and makes it possible to manufacture a magnetic recording medium having high reliability at low cost.

[Brief description of the drawings]

FIG. 1 is a sectional view of a magnetic recording medium according to an embodiment of the present invention.

FIG. 2 is a diagram showing a change in projection height when the irradiation time of an electron beam is changed.

FIG. 3 is a cross-sectional view of a projection forming portion in one embodiment of the present invention.

FIG. 4 is a sectional view of a disk for calibrating a head for projection detection according to another embodiment of the present invention.

[Explanation of symbols]

1 tempered glass substrate, 2 base film, 3 magnetic film, 4 protective film, 5 lubricating film

Claims (6)

[Claims] An electron beam is irradiated on a non-magnetic substrate made of glass or ceramic to form a large number of projections on the surface, and a magnetic film made of a magnetic material is formed on the substrate on which the projections are formed. Forming a protective film on the magnetic film,
A method for manufacturing a magnetic recording medium, further comprising applying a lubricating film on the protective film. 2. A chromium deposition layer is formed on a non-magnetic substrate to form a substrate, and a large number of projections are formed on the surface by irradiating the substrate with an electron beam. Forming a magnetic film made of a magnetic material, forming a protective film on the magnetic film, and applying a lubricating film on the protective film. 3. A magnetic recording medium comprising a magnetic film made of a magnetic material formed on a non-magnetic substrate made of glass or ceramic, a protective film formed on the magnetic film, and a lubricating film. A magnetic recording medium, wherein the substrate has a large number of protrusions on the surface. 4. The magnetic recording medium according to claim 3, wherein the plurality of protrusions formed on the substrate are formed by irradiating the surface of the substrate with an electron beam. 5. A substrate composed of a non-magnetic substrate made of glass or ceramic, a deposited layer formed on the non-magnetic substrate, a magnetic film composed of a magnetic material formed on the substrate, and a magnetic film formed on the substrate. A magnetic recording medium comprising a protective film and a lubricating film formed on the substrate, wherein the substrate has a large number of projections on a surface. 6. The magnetic recording medium according to claim 5, wherein the plurality of projections formed on the substrate are formed by irradiating the surface of the substrate with an electron beam.