JP2003301257A - Method for forming carbonaceous film and method for manufacturing magnetic disc - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a carbonaceous thin-film having an improved recording density and an improved reliability against sliding of a magnetic disc. <P>SOLUTION: In the method for manufacturing the magnetic disc, an ion treatment of an element other than carbon is applied on a cathode 6 consisting of carbon, and arc discharge is generated on the surface of the cathode and a generated ion species is induced to a substrate 5 to form the thin-film by combining the carbon with the element other than carbon on the surface of the substrate. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for forming a carbonaceous film having good sliding durability, a method for producing a magnetic disk using the method, a carbonaceous thin film produced by the method, and a carbonaceous film forming apparatus. Regarding

[0002]

2. Description of the Related Art Magnetic disk devices are becoming more and more important as large-capacity information storage media, and are becoming popular not only as conventional computers and personal computers but also as image and sound recording devices. This is because the miniaturization, large capacity, and cost reduction by improving the recording density are progressing at an amazing speed. Technological innovation for this purpose is progressing daily, and it is necessary to innovate conventional technologies one after another. In particular, in order to improve the recording density, it is necessary to minimize the gap between the magnetic head and the magnetic recording medium, that is, the spacing loss, and reduce the protective film thickness, the lubricating layer thickness, and the flying height of the head that are contained in the gap. ,
And it needs to be flattened. Number 1 realized today
At 0 Gb / in ² , this distance is 20 nm or more,
Although the protective film thickness is several nm, it is necessary to make the film thinner than 2.5 nm in the future. With such a thickness, conventional diamond-like carbon or the like has only a few atomic layers, and for example, the skin can be seen through the protective film.
Therefore, in order to secure the corrosion resistance and strength, it is essential to raise the atomic density and the bond density.

Diamond has a high density of carbon-based coatings, but since it is a polycrystalline coating, grain boundaries become weak points, and it is presumed that the carbon-based coatings are weakened mechanically and chemically. Recently, an amorphous carbon film having a density comparable to that of diamond, so-called tetrahedral amorphous carbon (hereinafter, abbreviated as ta-C) has been found, and is being studied as a magnetic disk protective film.
However, the disadvantages of ta-C are high Young's modulus and compressive stress, and even if the protective film itself is strong, when the corner of the magnetic head hits or foreign matter is caught, stress concentrates in the magnetic layer below the protective film. However, a mode occurs in which the root is destroyed. In addition, the frictional force increases during high-speed sliding with the head,
The phenomenon of the head fluttering easily occurs.

Usually, the frictional force as described above is reduced by the lubricating layer. However, in the case of ta-C, the adhesive force at the interface between the lubricating layer and ta-C is small, so that it is easily stripped off at the time of contact and the Young's modulus is Since it is high, the frictional force generated at the time of contact also becomes large, and there is a problem in that the vibration of the head becomes large and the film is destroyed.

Attempts have been made to lower the Young's modulus and improve the adhesion of the lubricating layer by adding an element such as N in ta-C.
IEE Transaction on Magnetics, Vol. 37, No. 4, pp. 1789-1791 (200
1 year) (IEEE Transaction on M
agnetics, Vol. 37, No. 4,1789
~ 1791 (2001)).

[0006]

In the prior art described above, generally, ta-C is formed by a method called filtered cathodic arc vapor deposition, and even if nitrogen is mixed as a gas, the arc is suppressed or ion selection is unstable. So that
No consideration was given to the fact that it is difficult to combine the compounds in a preferable structure and ratio.

Thus, at the ultra-thin film level, for example,
A protective film having a level of 2.5 nm or less and capable of withstanding extremely low levitation required in the future has not been sufficiently studied.

A first object of the present invention is to provide a method for forming a carbonaceous film which is less likely to be damaged by high-speed low-flying sliding and has high durability. A second object of the present invention is to provide a carbonaceous film which is less likely to be damaged by high-speed low-flying sliding and has high durability. A third object of the present invention is to provide a method of manufacturing a magnetic disk which is less damaged during high speed low floating sliding and has high durability. A fourth object of the present invention is to provide a device for forming a carbonaceous film which is less likely to be damaged by high-speed low-floating sliding and has high durability.

[0009]

In order to achieve the above-mentioned first object, the method for forming a carbonaceous film of the present invention is such that a cathode made of carbon is subjected to ion treatment of an element other than carbon, and the surface of the cathode is An arc discharge is generated, the generated ion species are induced in the substrate, and a thin film of carbon and a combination of elements other than carbon is formed on the substrate surface. Ions other than carbon are nitrogen ions or oxygen ions. It is preferable.
The thin film formed on the surface of the substrate does not have to be a thin film in which all carbon and elements other than carbon are combined, but may have only carbon. When the element other than carbon is oxygen, it is preferably contained in the range of 2 to 10 atom%, and when it is nitrogen, it is preferably contained in the range of 10 to 30 atom%. When an element other than carbon is contained in this range, when the carbon can maintain the ta-C structure and there is something that slides on the carbonaceous film,
A film with little damage and excellent durability. The thickness of the film is preferably 0.5 nm to 2.5 nm. 0.
This is because if it is less than 5 nm, it is difficult to form a uniform thin film.

In order to achieve the above second object,
The carbon thin film of the present invention has a density of 2.5 to 3.5 g / cm.
A thin film comprising a tetrahedral amorphous carbon of ³ and having a structure in which an element other than carbon is combined with this carbon, wherein the element other than carbon is oxygen or nitrogen, and the element other than carbon is oxygen. Is contained in an amount in the range of 2 atom% to 10 atom%, and when the element other than carbon is nitrogen, it is contained in an amount in the range of 10 atom% to 30 atom%. Is.

The thin film preferably has a thickness in the range of 0.5 nm to 2.5 nm. Further, it is preferable that the density is in the above range because the corrosion resistance and the strength can be secured. As described above, the thin film does not have to be a thin film in which all carbon and elements other than carbon are combined, but may have only carbon. The reason for the preferable range of containing elements other than carbon is the same as above.

Further, in order to achieve the third object,
The method for manufacturing a magnetic disk of the present invention comprises:
After forming at least a magnetic layer, a carbonaceous thin film is formed by the above-mentioned carbonaceous film forming method.

The preferred ions other than carbon, the preferred range of inclusion thereof, the preferred state of the thin film and the like are all the same as described above. In particular, the magnetic disk has a film thickness of 2.
If the thickness exceeds 5 nm, it is difficult to achieve extremely low flying height of the head, so the thickness is preferably in the range of 0.5 nm to 2.5 nm.

In order to achieve the above-mentioned fourth object,
The carbonaceous film forming apparatus of the present invention is an arc generating means for generating an arc discharge on the cathode surface made of carbon, a guiding means for guiding the generated ions to the surface of the substrate to be treated, and an ion of an element other than carbon on the cathode surface. An ion treatment means for performing treatment and a control means for controlling the cathode so as to generate the arc discharge after the cathode is ion-treated with an element other than carbon.

The above-mentioned control means preferably controls, for example, ion treatment and arc discharge in sequence and repeats them. That is, any means may be used as long as the cathode is subjected to the ion treatment for a desired time, the ion treatment is stopped, the arc discharge is performed for a desired time, and the control is repeated. In addition, the positions of the ion-processed part and the arc-discharged part are divided, for example, the left half of the cathode is the ion-processed part and the right half is the arc-discharged part. Any means may be used as long as it is a means for controlling the cathode to rotate using a partitioning and rotating means.

[0016]

BEST MODE FOR CARRYING OUT THE INVENTION An example of a carbonaceous film forming apparatus suitable for carrying out the method of the present invention will be described. FIG. 1 is a schematic sectional view of a carbonaceous film forming apparatus. An arc vapor deposition source 2 is provided inside a vacuum container 1, and ion species generated from this are accelerated by an electrode 3 at a constant voltage and guided by a magnetic field generated by a solenoid coil 4 so as to be incident on a substrate 5 to form a carbonaceous film. Deposit. This feature is in the structure of the arc evaporation source 2. That is, the columnar cathode 6 made of carbon
Further, an arc generating mechanism 7 for generating an arc is provided so as to face a part of one of the cathode end surfaces 6 '. An ion processing mechanism 8 is provided so as to face a portion of the cathode end surface 6 ′ opposite to the arc generating mechanism 7. A shielding plate is provided between the arc generating mechanism 7 and the ion processing mechanism 8 so that the arc generating portion is not directly ion-processed.

The ion treatment used in the present invention is to treat the cathode surface by generating ions. For example, glow discharge treatment such as direct current discharge, alternating current discharge, high frequency discharge, ion irradiation treatment using various ion guns, or There is a process using photoionization. However, it is preferable that the gas can operate at a low gas pressure so as not to hinder the arc generation, and if possible, it is preferable to prevent the pressure increase of the arc source by separating the ion generation source using differential exhaust. 2, 3 and 4 show an example of an ion treatment apparatus which can be preferably used in the present invention. That is, FIG. 2 shows a hollow cathode type ion source in which ions are extracted from the plasma generated in the hollow cathode 9 by the grid 10. Figure 3 shows ECR
Type ion source, the microwave supplied from the microwave source 11 is guided by the waveguide 12, ECR plasma is generated in the reaction chamber 14 by the magnetic field generated by the coil 13, and ions are extracted by the grid 15. .
Further, in FIG. 4, a voltage is applied to the flat plate electrode 16 which is located close to the cathode 6 to generate plasma. Power supply 17
A DC power supply, an AC power supply, or a high-frequency power supply can be used for this, and it can be changed according to the gas used and the processing conditions. Further, a space is formed by keeping a narrow gap 18 so that plasma does not leak to the outside. In any case, the raw material is supplied as gas from the supply facility 19 and exhausted from the exhaust facility 20 to prevent the raw material from flowing into the arc generation site.

The treated ionic species used in the present invention are preferably those which form a covalent bond with carbon, and nitrogen, oxygen or the like can be used. Nitrogen and oxygen are excellent because they can eliminate the distorted bond of ta-C without lowering the density. Hydrogen is also useful for strain relief, but increasing the ratio causes a decrease in density, so
Limited effect.

In the present invention, in order to continuously perform the film forming treatment, the cathode is rotated while simultaneously performing the arc vapor deposition and the ion treatment, or the arc vapor deposition and the ion treatment are alternately performed so that the cathode is cycled every cycle. It is advisable to control so that the surface which is rotated and ion-treated is always at the arc generation site. Even if the ion treatment is not used, the same effect can be expected by exposing the part other than the arc generation part to a specific gas atmosphere. However, in this case, since the physical adsorption gas is used, the effect is small, and the effect is obtained only when the evaporation amount by arc vapor deposition is sufficiently small. The gases that can be used in this case are nitrogen, oxygen, etc., but if you bring in a gas with a higher adsorptive property such as NH ₃ , N ₂ O, NO, NO ₂ , H ₂ O, or CO ₂ , increase the gas pressure. Even if it does not exist, the effect can be obtained and it does not hinder the operation of arc vapor deposition.

The reason why the Young's modulus and internal stress of ta-C can be reduced by the present invention is estimated as follows. ta
In the initial stage of the formation of -C, carbon atoms are first thinly deposited on the surface of the substrate. Since the graphite structure is stable in terms of thermal equilibrium, we will try to adopt this structure first, but because carbon ions with uniform energy enter into the network of sp2 bonds of the carbon atoms that have been created while partially destroying the structure, distortion occurs. Sp3 binding occurs. Therefore, crystal growth does not occur and it becomes amorphous, and a high compressive stress is generated inside. In addition, the strain energy resists deformation, so that the Young's modulus also increases. When nitrogen ions or oxygen ions are introduced in this process, carbon atoms are partially replaced with these atoms, so that a rotatable bond such as -CN = C- or -C-O-C- is introduced, resulting in strain. It is stabilized by changing the arrangement in the direction that eliminates.

The carbonaceous film obtained is one in which nitrogen and oxygen are bound to carbon, and a similar film can be obtained by a sputtering method in which an inert gas is mixed with nitrogen and oxygen. However, the carbonaceous film obtained by sputtering is essentially s
Since it is mainly composed of p2 bonds, it is not possible to obtain a film having a high density as intended in the present invention. Further, the bonds of nitrogen and oxygen atoms taken from the gas component into the film are likely to be terminal bonds like C≡N or C═O, and a strong network cannot be formed. By accelerating and injecting in the form of N ⁺ and O ⁺ ions as in the present invention, C-
A bond such as N = C- or C-O-C is obtained. <Example 1> As an example of the present invention, an example applied to a process of forming a magnetic disk protective film will be described. FIG. 5 is a partial cross-sectional view of the manufactured magnetic disk. As the non-magnetic substrate 21, normally used tempered glass, crystallized glass, NiP plated aluminum-magnesium alloy or the like can be used. As the substrate, a disc having a predetermined outer diameter such as 2.5 inches and 3.5 inches, which has a hole for mounting the spindle motor at the center, is used. The thickness, end face shape, etc. may be determined according to the application, and the present invention is not limited to this. In addition to the commonly used non-magnetic NiP-plated aluminum-magnesium alloy, the surface-reinforced glass substrate, and the like, other non-magnetic substrate materials can be used as well. However, the flatness of the surface is important, and it is preferable to use a flat surface as much as possible.

The substrate is left as it is, or after surface treatment called texturing is performed, cleaning is performed to reduce defects. Combining a process of scrubbing dust and contaminants on the surface with a brush or a pad while supplying detergent, a process of superimposing ultrasonic waves on a pure water spray to remove minute foreign substances, a process of spin drying, warm air drying, etc. Good to do. It is also possible to incorporate a step of dissolving the surface layer with an acid or an alkali, or a step of modifying the surface by plasma treatment or the like. The present invention can be carried out regardless of these steps. If necessary, it is possible to form irregularities for preventing adhesion in the start / stop area of the head, the so-called CSS zone. For example, the irregularities formed when the substrate material in that portion is melted and solidified is appropriate. They may be arranged at various intervals. In addition, in FIG. 5, these processes,
Illustration of the concavo-convex formation is omitted.

Next, in order to control the crystallinity of the magnetic film of the recording layer 23, the substrate is heated in a vacuum, an appropriate underlayer 22 is provided by sputtering, and then a ferromagnetic material layer is formed. The heating temperature varies depending on the desired magnetic characteristics, but is approximately 150 ° C. to 300 ° C., and the underlayer 22 is often made of Cr or an alloy of Cr that has a good lattice matching with the recording layer 23. The base layer 22 and the recording layer 23 may each be composed of a plurality of layers instead of one layer. Recording layer 2
The surface of 3 is provided with a carbonaceous film 24 according to the present invention,
Further, a fluorine-based lubricating oil layer 25 is formed thereon.
In order to form the lubricating oil layer 25 on the carbonaceous film 24 which is a protective layer, a method in which a bath in which lubricating oil is dissolved in a solvent at a constant concentration is provided and the disc substrate is dipped in the bath and gently pulled up, or the disc surface is fixed It is possible to use a spin coating method or the like in which an amount of the solution is dropped and the disk substrate is rotated and coated. If the thickness of the lubricating oil layer 25 is too thick, it will stick to the contact surface with the head and stick to it, so it is preferable to be thin, but if it is too thin, the effect is small, so about 5-20Å is preferable. The magnetic disk manufactured as described above can be used as a magnetic disk device by combining and mounting it with a magnetic head.

In this embodiment, the layer structure is as follows, and the recording film 23 is formed by sputtering. Substrate: Crystallized glass substrate, 65 mmφ, plate thickness 0.635
mm Base film 1: NiTa alloy, thickness 30 nm Base film 2: CoCrTa alloy, thickness 10 nm Recording film 1: CoCrPt alloy, thickness 5 nm Recording film 2: Ru, thickness 2 nm Recording film 3: CoCrPtB, thickness 20 nm In forming the carbonaceous protective film on the substrate, the parallel plate type plasma source shown in FIG. 4 was used as the ion treatment mechanism. Inside the arc evaporation source, nitrogen gas is previously supplied to generate plasma, and the cathode is rotated. Next, an arc is generated. The generated ions are bent by the magnetic field created by the solenoid coil, and move along the tube while drawing a spiral orbit. The beam scanning coil is adjusted to allow the beam to move out of the substrate position. Next, the substrate on which the recording film was formed was moved to the substrate position, and the beam scanning coil was adjusted so that the beam hits the substrate position. When the beam was applied for 3 seconds at an arc current of 15 A, 2n
A m-thick nitrogen-containing carbon was obtained. The density of this film was 2.9 g / cm ³ . The nitrogen ratio is 18%
Met. When the hardness and Young's modulus were measured by the micro indentation method, the hardness at the indentation depth of 10 nm was 2
The Young's modulus was 2 GPa and 140 GPa. Next, a molecular weight of 4000 and both end groups were CH2
OH perfluoropolyether lubricant is 15Å on average
Applied to the thickness of.

A test was carried out in which the magnetic disk thus prepared was incorporated into a drive and the load-seek-unload cycle was repeated 1,000,000 times. The results were good, with neither scratches nor increase in errors. Furthermore, the magnetic disk after the test is placed in an environment of 60 ° C and 95%.
Stored for 00 hr. After that, when the amount of Co on the disk surface was measured by the secondary ion spectrum analysis method, no precipitation of Co was observed and good corrosion resistance was exhibited. <Embodiment 2> As another embodiment of the present invention, an example used in a magnetic disk for perpendicular magnetic recording will be described. FIG. 6 is a partial sectional view of the magnetic disk. The difference from the magnetic disk shown in FIG. 5 is that a backing layer 26 made of a soft magnetic material is provided on the non-magnetic substrate 21. Backing layer 26
May be a single layer, or may be a laminate of a plurality of layers. Further, the perpendicular magnetic recording film is a magnetic film having a structure in which the easy axis of magnetization is oriented in the direction perpendicular to the substrate, and a CoCr-based alloy thin film or a very thin layer of Co and Pt or Pd is used in the range of 10 to 30.
A thin film having an artificial lattice structure in which layers are stacked can be used. In this embodiment, a CoCrTa alloy is used for the backing layer,
Sputtering was performed to a thickness of 200 nm.

Next, this substrate is heated to 200 ° C., and a Cr underlayer film of 30 nm is formed on CoCrTa by a continuous multilayer film forming apparatus.
Formed, Co is 1.3 nm thick, Pd is 0.7 nm thick
Was repeated 20 times to form an artificial lattice recording film. A carbonaceous film 24 containing nitrogen and a lubricating oil layer 25 were formed on this substrate in the same manner as in Example 1, and the same evaluation was performed. The results showed good sliding resistance and corrosion resistance as in Example 1. <Example 3> A magnetic disk was prepared by the same process as in Example 1, except that the treating ions were oxygen. The carbonaceous film obtained had an oxygen content of 5%, a density of 2.7 g / cm ³ , a hardness of 20 GPa, and a Young's modulus of 120 G.
It was Pa. When the same evaluation as that of Example 1 was performed, the result showed good sliding resistance and corrosion resistance as in Example 1. <Comparative Example 1> According to the manufacturing method of Example 1, a carbonaceous film was formed in an amount of 20 l without performing ion treatment. The obtained carbonaceous film had a density of 3.2 g / cm ³ , a hardness of 35 GPa and a Young's modulus of 280 GPa. As a result of performing the same evaluation as in Example 1 on this magnetic disk, a crash occurred at 1,500 cycles of loading / unloading. Comparative Example 2 In the manufacturing method of Example 1, the protective film 24 was not formed by the method of the present invention, but a nitrogenated carbon protective film formed by sputtering in an argon-nitrogen atmosphere was used.
The film thickness was 20Å. Other than that, when a disk was prepared and evaluated in the same manner as in Example 1, the nitrogen content was 18%, but the density was 1.8 g / cm ^3, which was lower than that of the present invention.
The hardness was 10 GPa and the Young's modulus was 120 GPa, and the load / unload cycle was less than 100 times and the vehicle crashed. As a result of the corrosion resistance test, Co oxide particles were observed on the surface.

[0027]

According to the present invention, it is possible to obtain a carbonaceous film having sufficient strength and sliding resistance even with a protective film having a substantial thickness of 2.5 nm or less. The carbon thin film of the present invention had excellent strength and good sliding durability. Further, the magnetic disk obtained by the method for producing a magnetic disk of the present invention had good sliding durability, excellent strength, and improved adhesive resistance of the lubricant. Further, the carbonaceous film forming apparatus of the present invention had good sliding durability and could easily produce a carbonaceous thin film having excellent strength.

[Brief description of drawings]

FIG. 1 is a schematic view showing a carbonaceous film forming apparatus of the present invention.

FIG. 2 is a sectional view showing an example of a hollow cathode ion source used in the present invention.

FIG. 3 is a cross-sectional view showing an example of an ECR type ion source used in the present invention.

FIG. 4 is a sectional view showing an example of a parallel plate type ion source used in the present invention.

FIG. 5 is a partial cross-sectional view of an embodiment of a magnetic disk manufactured according to the present invention.

FIG. 6 is a partial cross-sectional view of another embodiment of a magnetic disk manufactured according to the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Vacuum container, 2 ... Arc vapor deposition source, 3 ... Electrode, 4 ... Solenoid coil, 5 ... Substrate, 6 ... Cathode, 6 '... Cathode end face, 7 ... Arc generating mechanism, 8 ... Ion processing mechanism, 9
... Hollow cathode, 10 ... Grid, 11 ... Microwave source, 12 ... Waveguide, 13 ... Coil, 14 ... Reaction chamber, 15
... grid, 16 ... flat plate electrode, 17 ... power supply, 18 ... gap, 19 ... gas supply equipment, 20 ... exhaust equipment, 21 ... non-magnetic substrate, 22 ... underlayer, 23 ... recording layer, 24 ... carbonaceous film, 25 ... Lubricating oil layer, 26 ... Backing layer.

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Toshinori Ohno             2880 Kozu, Odawara City, Kanagawa Stock Association             Storage Systems Division, Hitachi, Ltd. F-term (reference) 4G146 AA01 AA15 AB07 AC15A                       AD02 AD28 BA42 DA17                 4K029 AA09 BA34 BC02 BD11 CA03                       DD06                 5D006 AA02 AA04 AA05                 5D112 AA07 BC05 FB04 FB11

Claims (5)

[Claims] 1. A cathode made of carbon is subjected to ion treatment of an element other than carbon to generate arc discharge on the surface of the cathode,
A method for forming a carbonaceous film, which comprises inducing generated ionic species to a substrate to form a thin film of carbon and an element other than carbon on the surface of the substrate. 2. The method for forming a carbonaceous film according to claim 1, wherein the ions other than carbon are nitrogen ions or oxygen ions. 3. A method of manufacturing a magnetic disk, comprising forming a carbon thin film by the carbonaceous film forming method according to claim 1 after forming at least a magnetic layer on a non-magnetic substrate. 4. An arc generating means for generating an arc discharge on a cathode surface made of carbon, an induction means for guiding the generated ions to a surface of a substrate to be treated, and an ion treatment for subjecting the cathode surface to an ion treatment of an element other than carbon. A carbonaceous film forming apparatus comprising: a means and a control means for controlling the cathode to generate the arc discharge after the cathode is ion-treated with an element other than carbon. 5. A thin film made of tetrahedral amorphous carbon having a density of 2.5 to 3.5 g / cm ³ and having a structure in which an element other than carbon is combined with the carbon,
The element other than carbon is oxygen or nitrogen, and when the element other than carbon is oxygen, an amount in the range of 2 atom% to 10 atom% is included, and the element other than carbon is nitrogen. In some cases, the carbon thin film contains an amount in the range of 10 atom% to 30 atom%.