JPH0836743A - Magnetic recording medium and manufacture thereof - Google Patents

Abstract

PURPOSE:To prevent the sticking of a magnetic head by forming a backing layer or a magnetic recording layer on a substrate and forming thereon a carbon component having a fullerene structure or the aggregate thereof in an island form to produce the irregularities of uniform size and density on the surface of a protective layer. CONSTITUTION:Ar ions are moved and made to collide against the target 25 of fullerene and to splash fullerene particles toward the surface of a substrate 11 for adhesion. The fullerene particles made to adhere to the substrate 11 awe on the surface of the substrate 11 with the energy of a substrate heating temperature and aggregate, so that the fullerene cluster 12 of a suitable size of about 10nm may be formed. The fullerene is the mixture of molecules of C60, C70, C76, C78, C80 and the like and the particle diameter thereof is as small as 7 to 30Angstrom . Next, the fullerene cluster 12 is covered by a spattering method thereon to form a Cr film fl of about 50nm thick and further thereon to form a CoCr12 Ta2 film 14 of about 15nm thick. Next, thereon, a C film 15 of about 10nm thick is formed as a protective layer by a spattering method.

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 method for manufacturing the same, and more specifically, to a CSS (contact
BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetic recording medium of a start / stop type and a method of manufacturing the magnetic recording medium provided with means for preventing the magnetic head from adsorbing to the magnetic recording medium when the magnetic recording medium stands still.

[0002]

2. Description of the Related Art FIG. 5A is a side view of a main portion of a conventional CSS type magnetic disk device. The CSS type magnetic disk device magnetically records information, or reads magnetically recorded information from the magnetic disk 1 on which information is already magnetically recorded, or magnetically records information on the magnetic disk 1 via magnetism. Head slider 2 for writing information on
Have and. A suspension 3 applies a pressing force to the magnetic head slider 2 toward the magnetic disk 1. Reference numeral 4 denotes a rotation shaft that imparts rotation to the magnetic disk 1.

As shown in FIG. 5B, the magnetic head slider 2 has a suspension 3 when the magnetic disk 1 is stationary.
5 is pressed by the magnetic disk 1 and comes into contact with the surface of the magnetic disk 1.
As shown in (c), as the magnetic disk 1 rotates at a high speed, it is lifted from the surface of the magnetic disk 1 by the air flow. At this time, due to the balance between the pressing force and the levitation force, an appropriate levitation gap (spacing) 5 is formed between the surface of the magnetic disk and the magnetic head slider. As the density is further increased, the floating gap 5 is becoming smaller and is on the order of submicron.

Therefore, it is necessary to flatten the surface of the magnetic disk 1. However, if it is too smooth, the magnetic head slider 2 will be attracted to the surface of the recording medium when the magnetic disk 1 is at rest, and the magnetic disk 1 will start up. The magnetic head slider 2 and the magnetic disk 1 may be damaged. Therefore, the magnetic head 2 is not attracted to the magnetic disk 1,
In addition, a treatment for producing minute irregularities on the surface of the magnetic disk 1 is performed to the extent that the magnetic recording characteristics are not hindered.

That is, firstly, the substrate surface of the magnetic disk 1 is textured to roughen the substrate surface appropriately, and a magnetic recording layer or a protective layer for protecting the magnetic recording layer is formed thereon. There is a way. Another method has been tried in which non-magnetic fine particles such as SiO ₂ are mixed in the protective layer to obtain a surface having an appropriate roughness corresponding to the size of the non-magnetic fine particles (Japanese Patent Laid-Open No. 5-282666). .

[0006]

However, the method of texturing the substrate as described above is based on mechanical polishing using a polishing tape or the like, and the projections and depressions of the unevenness are sharper than necessary. And it tends to be expensive. With higher density recording, in the present situation where the unevenness is smaller and the size and density are uniform, the conventional texture processing by mechanical polishing is not sufficient.

Further, in the method of mixing non-magnetic fine particles, when the particle diameter is set to 10 nm or less, a head adsorption phenomenon occurs, so that a low flying height for realizing a recording density of 1 Gb or more per square inch is realized. Making it difficult. On the other hand, since graphite has solid lubricity, it is expected to reduce the head adsorption phenomenon by using it in place of SiO ₂ particles.
Since the following fine particles cannot be used, little effect can be expected for application to a magnetic recording medium suitable for higher density recording.

The present invention has been made in view of the problems of the conventional example, and in a CSS type magnetic recording apparatus, magnetic fields are formed by forming minute irregularities having a uniform size and density. An object of the present invention is to provide a magnetic recording medium and a method for manufacturing the same that can avoid the attraction of a head.

[0009]

The first object of the present invention is to provide a magnetic recording medium in which an underlayer, a magnetic recording layer, and a protective layer are laminated on a substrate, and on the substrate, the lower layer. A magnetic recording medium characterized in that carbon molecules having a fullerene structure or aggregates thereof are formed in an island shape on the formation or on the magnetic recording layer.
According to a third aspect of the present invention, there is provided a magnetic recording medium according to the first invention, wherein the carbon molecule having a fullerene structure or an aggregate thereof is mainly composed of C ₆₀ molecules or C ₆₀ molecules. In the method of manufacturing a magnetic recording medium having a substrate, an underlayer, a magnetic recording layer, and a protective layer, carbon molecules having a fullerene structure on the substrate, on the underlayer, or on the magnetic recording layer. Alternatively, it is achieved by a method for manufacturing a magnetic recording medium, which is characterized in that an aggregate of them is formed into an island shape. Then, by sputtering the carbon molecules from the target, the carbon molecules having the fullerene structure or the carbon molecules having the fullerene structure are formed on the substrate, the underlayer, or the magnetic recording layer. And a carbon molecule having the fullerene structure in a state where the substrate is heated, which is achieved by the method for producing a magnetic recording medium according to the third invention, wherein the aggregate is formed in an island shape. The fullerene on the substrate, on the underlayer or on the magnetic recording layer by evaporating the carbon molecules from the melt and applying energy to the vaporized carbon molecules by electron irradiation. This is achieved by the method for producing a magnetic recording medium according to the third aspect of the present invention, which comprises forming a carbon molecule having a structure or an aggregate thereof in an island shape. Sixth, a carbon molecule having the fullerene structure or these aggregate is achieved by the method for producing a magnetic recording medium according to any one of the third to fifth invention is characterized in that mainly the C ₆₀ molecule or C ₆₀ molecules .

[0010]

In the magnetic recording medium of the present invention, on the substrate,
Carbon (C) molecules having a fullerene structure or their aggregates are formed in an island shape on the underlayer or on the magnetic recording layer. Fullerene is a mixture of carbon molecules such as C ₆₀ , C ₇₀ , C ₇₆ , C ₇₈ , and C ₈₀ , and has a molecular diameter of 7 to 30Å.
It is small and uniform in size. Therefore, the size of these clusters is 10 nm.
It is uniform and the density is uniform.

Therefore, since the surface of the uppermost protective layer that covers the clusters has irregularities of an appropriate size and is uniform in size and density, it is possible to reduce the flying height. Further, carbon molecules having a fullerene structure can be expected to have an effect of solid lubricity, and according to experiments, an effect of preventing adsorption of the magnetic head, which is considered to be due to the effect, was also obtained.

This makes it possible to prevent the magnetic head from being attracted to the magnetic recording medium when the magnetic recording medium is stopped. Further, in the method for manufacturing a magnetic recording medium of the present invention,
In order to form carbon molecules having a fullerene structure or aggregates thereof in an island shape, a sputtering method is used in which carbon molecules are sputtered from the targets by bombarding the carbon molecules with ions while the substrate is heated. An ion beam vapor deposition method is used in which carbon molecules are evaporated from a melt of the carbon molecules in a heated state, and energy is applied to the evaporated carbon molecules by electron irradiation to deposit the carbon molecules.

That is, the carbon molecules deposited on the substrate or the like by the sputtering method or the ion beam deposition method are also C ₆₀ , C ₇₀ ,
It is composed of molecules forming fullerenes such as C ₇₆ , C ₇₈ and C ₈₀ . They respond to the energy obtained by ion bombardment or electron irradiation and the energy obtained by the substrate heating temperature, and move around and aggregate in response to their own weight, and clusters of appropriate size have uniform density. Is formed on a substrate or the like.

[0014]

Embodiments of the present invention will be described below with reference to the drawings. (1) Description of Manufacturing Method of Magnetic Recording Medium According to First Embodiment of Present Invention FIGS. 1A to 1D show a manufacturing method of magnetic recording medium according to a first embodiment of the present invention. FIG. C ₆₀ ,
A fullerene cluster composed of an aggregate of C ₇₀ , C ₇₆ , C ₇₈ , C _80, etc. is formed on a substrate. Moreover, a sputtering method is used to form a fullerene cluster.

First, as shown in FIG. 1A, a fullerene cluster 12 is formed on a substrate 11 made of tempered glass. The magnetron RF sputtering apparatus shown in FIG. 3 is used to form a fullerene by a sputtering method using a sintered target. The details will be described below.
Counter electrode 2 provided in film forming chamber 21 of the sputtering apparatus
The substrate 11 is placed on one of the opposing electrodes (mounting table) 24 of 4, 4 and 25, and the substrate 11 is evacuated from the exhaust port 22 and kept at a predetermined pressure. The other counter electrode 25 is a target made of fullerene.

Next, the substrate 11 is heated by a heater built in the counter electrode 24 and is kept at a temperature of about 150.degree. Then, Ar gas is introduced into the film forming chamber 21 through the gas introduction port 23 to maintain the pressure at 10 mTorr. Then, electric power having a power density of 2.74 W / cm ² is applied between the counter electrodes 24 and 25. As a result, the Ar gas is turned into plasma, and the electromagnetic field generated by the magnet 27 and the counter electrodes 24 and 25 causes A
The r ions move and collide with the fullerene target 25 to scatter the fullerene particles toward the surface of the substrate 11. The scattered fullerene particles adhere to the substrate 11.

The fullerene particles adhering to the surface of the substrate 11 also receive energy due to the substrate heating temperature, and
The fullerene clusters 12 having an appropriate size of about 10 nm are formed by moving on the surface and gathering. Fullerene is a mixture of molecules such as C ₆₀ , C ₇₀ , C ₇₆ , C ₇₈ , and C ₈₀ , and has a small molecular diameter of 7 to 30Å. Moreover, by adjusting the substrate heating temperature and the applied power density, it is possible to obtain clusters having a uniform size and density. In the case of the embodiment, the size of clusters is about 10 nm and uniform.

Next, the Ar gas pressure is 5 mT by the sputtering method.
Under the conditions of orr and the substrate temperature of 280 ° C., the fullerene cluster 12 is covered to form a Cr film (underlayer) 13 having a thickness of about 50 nm.
To form. Then, the Ar gas pressure is set to 5 by the sputtering method.
Under the conditions of mTorr and substrate temperature of 280 ° C., a CoCr ₁₂ Ta ₂ film (magnetic recording layer) 14 having a film thickness of about 15 nm is formed on the Cr film 13.
To form.

Then, the Ar gas pressure is set to 1 by the sputtering method.
CoCr ₁₂ Ta under conditions of 0 mTorr and substrate temperature of 280 ° C.
A C film (protective layer) 15 having a film thickness of about 10 nm is formed on the ₂ film 14. As a result, the magnetic recording medium is completed. At this time, since the size and density of the fullerene clusters 12 are uniform, the surface of the uppermost protective layer 15 that covers the fullerene clusters 12 has unevenness of an appropriate size, and the unevenness is uniform in size and density. Occurs. Therefore, low flying height can be achieved.

Next, the magnetic characteristics of the obtained magnetic recording medium were investigated. According to the result, the magnetic characteristics of the magnetic recording medium obtained with the system base pressure of 5 × 10 ⁻⁷ Torr are tBr = 100 G · μm and Hc = 1700 Oe.
That is, the value is sufficiently compatible with recent magnetic recording devices. Note that t represents the film thickness of the magnetic layer, and Br represents the residual magnetization of the magnetic recording medium after recording (H = 0). The output of the magnetic head is proportional to tBr. Hc represents a coercive force, and Hc of a certain size is required to maintain high density recording.

Next, the correlation between the density of the fullerene clusters 12 and the magnetic head adsorption was investigated for the obtained magnetic recording medium. The investigation was performed by measuring the slide-friction coefficient (μs) characteristics. The measurement conditions are as follows.・ Tester FJA (Fujitsu Automation) simple friction tester ・ Evaluation sample Fullerene clusters are present (Example of the present invention) Fullerene clusters are not (Comparative example) ・ Measurement method Rotation speed 100 rpm, sliding for 1 hour is repeated 3 times, The friction coefficient (μs) was measured at 1 rpm before and after sliding.

According to the measurement results, the fullerene cluster 1
In the case of forming No. 2, μs was 0.3 or less even after repeated measurement. On the other hand, in the case where the fullerene cluster 12 was not formed, μs at the start of measurement was about 0.8, and the protective layer 15 of the magnetic recording medium was destroyed by repeated measurement. As described above, according to the first embodiment of the present invention, the fullerene clusters 12 are formed in an island shape on the substrate 11, and the underlayer 13, the magnetic recording layer 14 and the protective layer 15 are laminated thereon. There is.

As described above, the fullerene cluster 12 formed on the heated substrate 11 by the sputtering method has a uniform size of about 10 nm and a uniform density. Therefore, the surface of the protective layer 15 has irregularities of appropriate height formed with appropriate density. Further, the fullerene cluster 12 can be expected to have the effect of solid lubricity, and the magnetic head adsorption preventing effect, which is considered to be due to the effect, can be obtained.

This makes it possible to reduce the flying height and prevent the magnetic head from adsorbing to the surface of the magnetic recording medium when the magnetic recording medium is stopped. (2) Description of Manufacturing Method of Magnetic Recording Medium According to Second Embodiment of Present Invention FIGS. 2A to 2D show a manufacturing method of magnetic recording medium according to the second embodiment of the present invention. FIG. The fullerene cluster 12a is formed on the magnetic recording layer 14a. Further, in order to form the fullerene cluster 12a, the cluster ion beam vapor deposition apparatus shown in FIG. 4 was used.

First, as shown in FIG. 2 (a), a substrate 11a made of tempered glass is sputtered to cover the substrate 11a under the conditions of Ar gas pressure of 5 mTorr and substrate temperature of 280 ° C. and a film thickness of about 50 nm. The Cr film (underlayer) 13a is formed. Then, Ar gas pressure of 5 mTorr,
The film thickness is about 15 on the Cr film 13a under the condition of the substrate temperature of 280 ° C.
A CoCr ₁₂ Ta ₂ film (magnetic recording layer) 14a having a thickness of 14 nm is formed.

Next, fullerene clusters 12a are formed on the CoCr ₁₂ Ta ₂ film 14a. For that purpose, the cluster ion beam vapor deposition apparatus shown in FIG. 4 is used. This is because C ₆₀ is melted and evaporated under reduced pressure, and kinetic energy is given to the cluster composed of C ₆₀ molecules evaporated by the ion beam,
Clusters are deposited on the heated substrate 11a. The details are described below.

The substrate 11a is placed on the holder 38 in the film forming chamber 31 of the vapor deposition apparatus, and is heated at a temperature of 150 ° C. by a heater built in the holder 38. Then, the exhaust port 32
The film forming chamber 31 is evacuated through the chamber to maintain the pressure at 1 × 10 ⁻⁶ Torr or higher. Then, under reduced pressure, crucible 33
The C ₆₀ solid placed in the above is heated to about 600 ° C. by the heater 34 to evaporate C ₆₀ molecules. The C ₆₀ molecules that have passed through the outlet of the crucible 33 undergo adiabatic expansion process to form molecular clusters. Further, these clusters are charged by an electron flow emitted from the cathode 35 to form an ion beam. Then, the ion beam is accelerated by the accelerating voltage (Vb) -600v applied between the accelerating electrodes 36a and 36b by the DC power source 37, and the ion beam is irradiated to evaporate C _60.
Adds more energy to the molecular cluster. The C ₆₀ molecular clusters that have gained energy move toward the substrate 11a and adhere to the surface of the substrate 11a. In this case, the vapor deposition rate is 2 nm / min.

The C ₆₀ molecular clusters adhering to the surface of the substrate 11a also receive energy due to the substrate heating temperature, and
The fullerene clusters 12a having a proper size are formed by moving on the surface and gathering. Then, by a sputtering method, Ar gas pressure is 10 mTorr and substrate temperature is 160 ° C.
Film thickness of about 10 nm on the CoCr ₁₂ Ta ₂ film 14a under the conditions of
C film (protective layer) 15a is formed. As a result, the magnetic recording medium is completed. The surface of the uppermost protective layer 15a covering the fullerene cluster 12a has irregularities of a suitable size, and irregularities of uniform size and density are produced.

Next, the surface roughness and glide height of the obtained magnetic recording medium were investigated. For comparison, a magnetic recording medium coated with a lubricant was similarly investigated.
The comparative sample was prepared as follows. That is, the surface roughness R
Cr film / CoCrTa film / C on glass substrate with a = 6Å
After sequentially forming the films, a lubricant was applied to the surface of the C film.

The surface roughness was investigated as follows. That is, the probe is brought into contact with the surface of the protective layer 15a, and the amount of vertical movement of the probe that fluctuates according to the unevenness of the surface is read. The glide height described below refers to the minimum flying height at which the magnetic head does not come into contact with the disk, which corresponds to approximately Rp (maximum height based on center line average roughness Ra (defined by JIS)). It is a thing.

According to the investigation result, the glide height of 30 nm was obtained in the sample according to the second embodiment in which the fullerene cluster 12a mainly composed of stable C ₆₀ was formed on the magnetic recording layer 14a. Further, in the investigation of magnetic head attraction, it was possible to avoid attraction of the magnetic head when the magnetic disk was stationary. On the other hand, the comparative sample has a surface roughness of 12
It became about Å and the glide height was about 18 nm.
Further, in this comparative sample, the adsorption phenomenon of the magnetic head was observed when the magnetic disk was at rest.

The reason why the head adsorption can be avoided in the sample according to the second embodiment is considered to be as follows. That is, C
Fullerenes mainly composed of ₆₀ formed clusters, and formed clusters having a diameter of about 10 nm and scattered at a uniform density on the magnetic recording layer 14a. As a result, the irregularities of appropriate size were formed on the surface of the magnetic disk with a uniform density. Therefore, it is considered that the contact area between the surface of the magnetic disk and the magnetic head was reduced when the magnetic disk was stationary. Alternatively, it is considered to be due to the effect of solid lubricity based on the fullerene cluster 12a. The reason why the head adsorption occurred in the comparative sample is considered to be that the unevenness was too small or the effect of solid lubricity could not be expected.

As described above, according to the second embodiment of the present invention, the fullerene cluster 12a is formed in an island shape on the magnetic recording layer 14a, and the protective layer 15a is further laminated thereon.
The fullerene molecule has a small molecular diameter of 7 to 30 Å and the size of the fullerene is uniform. Therefore, the fullerene clusters 12a, in which these are aggregated, have a uniform size of about 10 nm and have a uniform density. Therefore, irregularities of appropriate size are formed on the surface of the magnetic disk with a uniform density.

Further, the effect of solid lubricity based on the fullerene cluster 12a can be expected, and the effect of preventing adsorption of the magnetic head can be obtained. This makes it possible to reduce the flying height and prevent the magnetic head from being attracted to the magnetic recording medium when the magnetic recording medium is stopped. Although the fullerene clusters 12 or 12a are formed in an island shape on the substrate 11 or on the magnetic recording layer 14a in the above embodiment, they may be formed on the underlayer 13 or 13a.

Although tempered glass is used as the material of the substrates 11 and 11a, Ni-P, carbon, silicon or the like can be used.

[0036]

As described above, in the magnetic recording medium of the present invention, carbon molecules having a fullerene structure or aggregates thereof are formed like islands on a substrate, an underlayer or a magnetic recording layer. Become. The fullerene clusters are of a suitable size and have a uniform density.Therefore, the surface of the uppermost protective layer that covers the fullerene clusters has unevenness of a suitable size, and the size and density are uniform. Unevenness occurs. Further, the effect of solid lubricity based on fullerene clusters can be expected, and the effect of preventing magnetic head adsorption can be obtained.

This makes it possible to reduce the flying height and prevent the magnetic head from being attracted to the magnetic recording medium when the magnetic recording medium is stopped. Also,
In the method for producing a magnetic recording medium of the present invention, in order to form carbon molecules having a fullerene structure or an aggregate thereof in an island shape, a sputtering method of sputtering carbon molecules from a fullerene target in a state where a substrate is heated is used, Alternatively, an ion beam evaporation method is used in which carbon molecules are evaporated while the substrate is heated.

That is, by moving the fullerene molecules attached on the substrate or the like by the sputtering method or the ion beam deposition method, fullerene clusters of appropriate size can be formed on the substrate or the like with a uniform density.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing a method of forming a magnetic disk according to a first embodiment of the present invention.

FIG. 2 is a cross-sectional view showing a method of forming a magnetic disk according to a second embodiment of the present invention.

FIG. 3 is a side view showing a sputtering apparatus used for forming a fullerene cluster used in the magnetic disk according to the first embodiment of the present invention.

FIG. 4 is a side view showing an ion beam vapor deposition apparatus used for forming fullerene clusters used in the magnetic disk according to the second embodiment of the present invention.

FIG. 5 is a side view showing a CSS type magnetic recording apparatus according to a conventional example.

[Explanation of symbols]

11,11a substrate, 12,12a fullerene cluster, 13,13a Cr film (underlayer), 14,14a CoCr ₁₂ Ta ₂ film (magnetic recording layer), 15,15a C film (protective layer), 21,31 film formation Chamber, 22, 32 exhaust port, 23 gas inlet port, 24 counter electrode (mounting table), 25 counter electrode (fullerene target), 26 RF power source, 27 magnet, 33 crucible, 34 heater, 35 ionized filament, 36a , 36b accelerating electrode, 37 DC power supply, 38 holder.

Claims (6)

[Claims] 1. A magnetic recording medium in which an underlayer, a magnetic recording layer, and a protective layer are laminated on a substrate, wherein a fullerene structure is formed on the substrate, on the underlayer, or on the magnetic recording layer. A magnetic recording medium characterized by comprising carbon molecules having: or an aggregate thereof formed in an island shape. 2. The magnetic recording medium according to claim 1, wherein the carbon molecules having a fullerene structure or their aggregates are mainly composed of C ₆₀ molecules or C ₆₀ molecules. 3. A method of manufacturing a magnetic recording medium having a substrate, an underlayer, a magnetic recording layer, and a protective layer, wherein a fullerene structure is provided on the substrate, on the underlayer, or on the magnetic recording layer. A method of manufacturing a magnetic recording medium, which comprises forming the carbon molecule having the carbon atom or an aggregate thereof in an island shape. 4. The substrate is heated on the base layer, or by sputtering the carbon molecules from the target by colliding ions with a target of carbon molecules having the fullerene structure in a state where the substrate is heated. 4. The method for manufacturing a magnetic recording medium according to claim 3, wherein the carbon molecules having the fullerene structure or their aggregates are formed in an island shape on the magnetic recording layer. 5. Evaporating the carbon molecules from a melt of the carbon molecules having the fullerene structure while heating the substrate, and applying energy to the evaporated carbon molecules by electron irradiation to deposit the carbon molecules, 4. The magnetic recording medium according to claim 3, wherein carbon molecules having the fullerene structure or aggregates thereof are formed in an island shape on the substrate, on the underlayer or on the magnetic recording layer. Method. 6. The carbon molecule having a fullerene structure or an assembly thereof is mainly composed of C ₆₀ molecules or C ₆₀ molecules, according to claim 3, claim 4 or claim 5. Manufacturing method of magnetic recording medium.