JP2011065715A - Carbon film deposition method and method for manufacturing magnetic recording medium - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a carbon film deposition method for extending the life of a filament-shaped cathode electrode and forming a very hard and dense carbon film. <P>SOLUTION: The carbon film deposition method deposits a carbon film on the surface of a substrate D by introducing gas G as a raw material containing carbon in a pressure-reduced film depositing chamber 101, ionizing the gas G by electric discharge between a filament-shaped cathode electrode 104 heated by energization and an anode electrode 105 disposed around the electrode 104, and irradiating the surface of the substrate D with the accelerated ionized gas. After the cathode electrode 104 is carbonized while being rotated, the carbon film is deposited by using the carbonized cathode electrode 104. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a carbon film forming method and a magnetic recording medium manufacturing method.

  In recent years, in the field of magnetic recording media used for hard disk drives (HDD) and the like, the recording density has been remarkably improved, and recently, the recording density has continued to grow at a phenomenal rate of about 1.5 times a year. There are a variety of technologies that support such an increase in recording density. One of key technologies is a technology for controlling sliding characteristics between a magnetic head and a magnetic recording medium.

  For example, the CSS (contact activation stop) method called the Winchester format, in which the basic operation from the start to the stop of the magnetic head is the contact sliding-floating-contact sliding with respect to the magnetic recording medium, has become the mainstream of hard disk drives. Since then, contact sliding of the magnetic head on the magnetic recording medium has been unavoidable.

  For this reason, the problem about tribology between the magnetic head and the magnetic recording medium has become a fateful technical problem, and there are many efforts to improve the protective film laminated on the magnetic film of the magnetic recording medium. In addition, the wear resistance and sliding resistance on the surface of the medium are a major pillar for improving the reliability of the magnetic recording medium.

  As protective films for magnetic recording media, films made of various materials have been proposed, but carbon films are mainly used from a comprehensive viewpoint such as film formability and durability. Further, the hardness, density, dynamic friction coefficient, etc. of the carbon film are very important because they are reflected in the CSS characteristics or corrosion resistance characteristics of the magnetic recording medium.

  On the other hand, in order to improve the recording density of the magnetic recording medium, it is preferable to reduce the flying height (flying height) of the magnetic head, increase the rotational speed of the medium, and the like. Accordingly, the protective film formed on the surface of the magnetic recording medium is required to have higher sliding durability and flatness in order to cope with accidental contact of the magnetic head. In addition, in order to reduce the spacing loss between the magnetic recording medium and the magnetic head and increase the recording density, the thickness of the protective film is required to be as thin as possible, for example, 30 mm or less. Accordingly, there is a strong demand for a thin, dense and tough protective film as well as smoothness.

  The carbon film used for the protective film of the magnetic recording medium described above is formed by sputtering, CVD, ion beam evaporation, or the like. Among these, the durability of the carbon film formed by the sputtering method may be insufficient when the film thickness is, for example, 100 mm or less. On the other hand, the carbon film formed by the CVD method has low surface smoothness, and when the film thickness is reduced, the coverage of the surface of the magnetic recording medium is lowered, and corrosion of the magnetic recording medium may occur. is there. On the other hand, the ion beam evaporation method can form a dense carbon film with higher hardness and higher smoothness than the above-described sputtering method or CVD method.

  As a method for forming a carbon film by ion beam evaporation, for example, a film forming material gas is changed to a plasma state by a discharge between a heated filament cathode and an anode in a film forming chamber in a vacuum atmosphere, and this is minus. A method has been proposed in which a carbon film having high hardness is stably formed by accelerated collision with a substrate surface at a potential. (See Patent Document 1).

JP 2000-226659 A

  By the way, in the method described in Patent Document 1, a filament obtained by energizing and heating a high melting point metal such as tungsten, tantalum, or molybdenum is used as an excitation source of the carbon raw material. In this case, it is possible to increase the hardness of the carbon film by increasing the filament temperature, increasing the anode current, and increasing the ion acceleration voltage. However, when the temperature of the filament is excessively increased, the filament may be broken or the filament material may be evaporated and mixed into the carbon film. For this reason, the filament is carbonized in advance to increase the melting point of the filament, but the filament may be deformed at that time, and this deformation adversely affects the film thickness distribution of the carbon film and the life of the filament. May affect. Furthermore, the filaments deformed during the carbonization treatment are often further deformed during the film formation, which causes a significant decrease in the filament life.

The present invention has been proposed in view of such a conventional situation, and while increasing the life of the filament-shaped cathode electrode, uniforming the film thickness distribution on the substrate surface, a high-hardness and dense carbon film can be obtained. It is an object of the present invention to provide a method for forming a carbon film that can be formed.
In addition, the present invention makes it possible to obtain a magnetic recording medium excellent in wear resistance and corrosion resistance by using a carbon film formed by such a method as a protective layer of the magnetic recording medium. It is an object of the present invention to provide a method for manufacturing a magnetic recording medium.

The present invention provides the following means.
(1) A raw material gas containing carbon is introduced into a decompressed film formation chamber, and this gas is ionized by discharge between a filamentary cathode electrode heated by energization and an anode electrode provided around the cathode electrode. , A method of forming a carbon film by accelerating the ionized gas and irradiating the surface of the substrate to form a carbon film on the surface of the substrate,
A carbon film forming method, wherein after carbonizing the cathode electrode while rotating, the carbon film is formed using the carbonized cathode electrode.
(2) The method for forming a carbon film as described in (1) above, wherein a filament made of tantalum is used as the cathode electrode, and the filament is carbonized while rotating the filament to form a filament made of tantalum carbide.
(3) The method for forming a carbon film as described in (1) or (2) above, wherein the cathode electrode is rotated during the carbonization treatment.
(4) The carbonization time is in the range of 5 to 30 minutes, the number of rotations of the cathode electrode during the carbonization treatment is in the range of 1 to 100 rpm, and the total carbon film formation time after the carbonization treatment is 50. The method for forming a carbon film as described in (3) above, which is 50 hours or longer.
(5) The method for forming a carbon film according to any one of (1) to (4), wherein the cathode electrode is rotated when the carbon film is formed.
(6) The magnet according to any one of (1) to (5), wherein a magnet for applying a magnetic field is disposed in a region for ionizing the gas of the raw material or a region for accelerating the ionized gas. A method for forming a carbon film.
(7) The method for forming a carbon film as described in (6) above, wherein a magnetic field is applied so that the acceleration direction of the ionized gas is parallel to the direction of the lines of magnetic force by the magnet.
(8) The preceding items (1) to (7), wherein a potential difference is provided between the cathode electrode or the anode electrode and the substrate, and the surface of the substrate is irradiated while accelerating the ionized gas. The method for forming a carbon film according to any one of the above.
(9) A method for forming a carbon film on a nonmagnetic substrate on which at least a magnetic layer is formed, using the method for forming a carbon film according to any one of (1) to (8). A method for manufacturing a magnetic recording medium.

  As described above, in the present invention, it is possible to suppress deformation during the deposition of the filamentary cathode electrode by performing carbonization while rotating the cathode electrode in advance. Therefore, when the carbon film is formed using the carbonized cathode electrode, it is possible to increase the life of the cathode electrode as compared with the conventional case.

  In addition, according to the present invention, it is possible to make the film thickness distribution on the substrate surface uniform and to form a high hardness and dense carbon film, and when this carbon film is used as a protective film such as a magnetic recording medium. Since the carbon film can be made thinner, the distance between the magnetic recording medium and the magnetic head can be set narrower. As a result, the recording density of the magnetic recording medium is increased and the magnetic It is possible to improve the corrosion resistance of the recording medium.

It is a schematic block diagram which shows typically the formation apparatus of the carbon film to which this invention is applied. It is a schematic diagram which shows the direction of the magnetic field which a magnet applies, and its magnetic force line. It is sectional drawing which shows an example of the magnetic recording medium manufactured by applying this invention. It is sectional drawing which shows the other example of the magnetic recording medium manufactured by applying this invention. It is sectional drawing which shows an example of a magnetic recording / reproducing apparatus. It is a top view which shows the structure of the in-line-type film-forming apparatus to which this invention is applied. It is a side view which shows the carrier of the in-line type film-forming apparatus to which this invention is applied. It is a side view which expands and shows the carrier shown in FIG.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
In addition, in the drawings used in the following description, in order to make the features easy to understand, there are cases where the portions that become the features are enlarged for the sake of convenience, and the dimensional ratios of the respective components are not always the same as the actual ones. Absent.

(Method for forming carbon film)
First, a method and apparatus for forming a carbon film to which the present invention is applied will be described.
FIG. 1 is a schematic configuration diagram schematically showing a carbon film forming apparatus to which the present invention is applied.
As shown in FIG. 1, this carbon film forming apparatus is a film forming apparatus using an ion beam evaporation method, and includes a film forming chamber 101 that can be decompressed, and a holder 102 that holds a substrate D in the film forming chamber 101. An introduction pipe 103 for introducing a raw material gas G containing carbon into the film forming chamber 101, a filamentary cathode electrode 104 disposed in the film forming chamber 101, and a cathode electrode 104 in the film forming chamber 101 The surrounding anode electrode 105, the first power source 106 for heating the cathode electrode 104 by energization, the second power source 107 for generating discharge between the cathode electrode 104 and the anode electrode 105, and the cathode electrode 104 Alternatively, a third power source 108 that applies a potential difference between the anode electrode 105 and the substrate D, and a magnet that applies a magnetic field between the cathode electrode 104 and the anode electrode 105 or the substrate D. It is schematically constituted by a preparative 109.

  The film forming chamber 101 is hermetically configured by a chamber wall 101a and can be evacuated through an exhaust pipe 110 connected to a vacuum pump (not shown).

  The first power source 106 is an AC power source connected to the cathode electrode 104, and supplies power to the cathode electrode 104 when the carbon film is formed. The first power source 106 is not limited to an AC power source, and a DC power source may be used.

  The second power source 107 is a DC power source in which the negative electrode side is connected to the cathode electrode 104 and the positive electrode side is connected to the anode electrode 105, and discharge is generated between the cathode electrode 104 and the anode electrode 105 when the carbon film is formed. Let

  The third power source 108 is a DC power source whose positive electrode side is connected to the anode electrode 105 and whose negative electrode side is connected to the holder 102. Between the anode electrode 105 and the substrate D held by the holder 102 when the carbon film is formed, Is given a potential difference. The third power supply 108 may have a configuration in which the positive electrode side is connected to the cathode electrode 104.

  The carbon film forming apparatus also includes a drive mechanism 120 that rotationally drives the cathode electrode 104. Here, the rotation referred to in the present invention includes the case where the filament is reciprocally rotated at an angle of less than 360 ° in addition to continuously rotating the filament in one direction beyond the angle of 360 °. In particular, in the case of a linear filament, it is preferable to reciprocate at an angle of 180 ° or more and less than 360 ° because of the symmetry of the shape. The cycle of reciprocating rotation is preferably in the range of 1 to 100 times / minute, and in this example, the optimum cycle is about 60 times / minute.

  The drive mechanism 120 includes a rotating plate 121 rotatably attached to the partition wall of the film forming chamber 101 and a driving motor 122 outside the film forming chamber 101, and the driving motor 122 causes the rotating plate 121 to move. It is possible to reciprocate in the circumferential direction. In addition, a pair of current introduction terminals 123 are attached to the rotating plate 121, and the first power source 106 outside the film formation chamber 101 and the inside of the film formation chamber 101 are connected via the current introduction terminals 123. A certain cathode electrode 104 is electrically connected. Then, it is possible to supply electric power from the first power source 106 to the cathode electrode 104 while rotating the cathode electrode 104 reciprocally in the circumferential direction by such a driving mechanism 120.

  In the present invention, although depending on the size of the substrate D, when a carbon film is formed on a disk-shaped substrate having an outer diameter of 3.5 inches, the voltage of the first power supply 106 is in the range of 10 to 100V. The current is preferably set to a range of 5 to 50 A by direct current or alternating current, and the second power source 107 is preferably set to a voltage of 50 to 300 V and a current of 10 to 5000 mA. For the third power supply 108, it is preferable to set the voltage in the range of 30 to 500 V and the current in the range of 10 to 200 mA.

  When forming a carbon film on the surface of the substrate D using the carbon film forming apparatus having the above-described structure, first, the cathode electrode 104 is carbonized while rotating the cathode electrode 104.

  Specifically, a high melting point metal such as tungsten, tantalum, or molybdenum can be used for the cathode electrode 104. Among them, a filament made of tantalum is used because of the high melting point of carbide and the stability of carbide. preferable. In the present invention, the source gas G containing carbon is introduced into the film forming chamber 101 evacuated through the exhaust pipe 110 through the introduction pipe 103, and the cathode electrode 104 is heated until the tantalum becomes stable tantalum carbide while being heated. Is gradually carbonized.

  At this time, it is possible to prevent deformation of the filament by performing carbonization while rotating the cathode electrode 104 using the drive mechanism 110. The carbonization time is preferably in the range of 5 to 30 minutes, and in this example, the optimum time is, for example, about 10 minutes. The rotation speed of the cathode electrode 104 is preferably in the range of 1 to 100 rpm. In this example, the optimum rotation speed is, for example, about 60 rpm.

  After the carbonization of the cathode electrode 104, a carbon film is formed using the cathode electrode 104 that has been carbonized. The cathode electrode 104 that has been carbonized using the method of the present invention has a small amount of deformation of the filaments before and after carbonization, and after the carbonization treatment, there is also little deformation with time when the carbon film is formed. Can be stably formed. Specifically, it is possible to continuously form a carbon film for 50 hours or more by one carbonization treatment of the cathode electrode 104.

  Formation of the carbon film after the carbonization treatment of the cathode electrode 104 introduces a raw material gas G containing carbon through the introduction pipe 103 into the film forming chamber 101 evacuated through the exhaust pipe 110. This raw material gas G is discharged between the thermal plasma of the cathode electrode 104 heated by the supply of electric power from the first power source 106 and the cathode electrode 104 and the anode electrode 105 connected to the second power source 107. It is excited and decomposed by the plasma generated by the above and becomes an ionized gas (carbon ion). Then, the carbon ions excited in the plasma collide with the surface of the substrate D while accelerating toward the substrate D which has been set to a negative potential by the third power source 108.

  Here, in the carbon film forming method to which the present invention is applied, a region in which the source gas G is ionized or an ionized gas (ion beam) by a magnet 109 made of a permanent magnet or an electromagnet arranged around the chamber wall 101a. The magnetic field is applied in a region (hereinafter referred to as excitation space) that accelerates. When a permanent magnet is used as the magnet 109, it is preferable to use a sintered magnet that can generate a strong magnetic field.

  In the present invention, when accelerating and irradiating the surface of the substrate D with carbon ions, the ion density of the carbon ions accelerated and irradiated toward the surface of the substrate D can be increased by applying a magnetic field from the outside. Thereby, when the ion density in the excitation space is increased, the excitation force in this excitation space is increased, and the surface of the substrate D can be accelerated and irradiated with carbon ions in a higher energy state. A carbon film having high hardness and high density can be formed on the surface of the substrate D.

  In the present invention, a magnetic field can be applied to the excitation space in the film forming chamber 101 by the magnet 109 provided around the cathode electrode 104 and the anode electrode 105 described above. For the direction, for example, a configuration as shown in FIGS. 2A to 2C can be employed.

  That is, in the configuration shown in FIG. 2A (the same configuration as shown in FIG. 1), the S pole is on the substrate D side and the N pole is on the cathode electrode 104 side around the chamber wall 101a of the film forming chamber 101. A magnet 109 is arranged so as to be. In this configuration, the lines of magnetic force M generated by the magnet 109 are substantially parallel to the acceleration direction of the ion beam B near the center of the film forming chamber 101. By setting the direction of the line of magnetic force M in the film forming chamber 101 to such a direction, carbon ions in the excitation space are concentrated near the center in the film forming chamber 101 by the magnetic moment, and the ions in the excitation space are concentrated. It is possible to increase the density efficiently.

  On the other hand, in the configuration shown in FIG. 2B, a magnet 109 is arranged around the chamber wall 101a of the film forming chamber 101 so that the S pole is on the cathode electrode 104 side and the N pole is on the substrate D side. On the other hand, in the configuration shown in FIG. 2C, around the chamber wall 101a of the film forming chamber 101, there are a plurality of magnets 109 in which the directions of the N pole and the S pole are alternately switched between the inner peripheral side and the outer peripheral side. Has been placed. In any case, the line of magnetic force M generated by the magnet 109 is substantially parallel to the acceleration direction of the ion beam B near the center of the film forming chamber 101, and this can efficiently increase the ion density in the excitation space. is there.

  In the carbon film forming method to which the present invention is applied, for example, a gas containing hydrocarbon can be used as the gas G of the raw material containing carbon. As the hydrocarbon, it is preferable to use one kind or two or more kinds of low carbon hydrocarbons among lower saturated hydrocarbons, lower unsaturated hydrocarbons, and lower cyclic hydrocarbons. Here, the term “lower” refers to a case of 1 to 10 carbon atoms.

  Among these, methane, ethane, propane, butane, octane, etc. can be used as the lower saturated hydrocarbon. On the other hand, as the lower unsaturated hydrocarbon, isoprene, ethylene, propylene, butylene, butadiene and the like can be used. On the other hand, as the lower cyclic hydrocarbon, benzene, toluene, xylene, styrene, naphthalene, cyclohexane, cyclohexadiene, or the like can be used.

  In the present invention, it is preferable to use a lower hydrocarbon because when the carbon number of the hydrocarbon exceeds the above range, it becomes difficult to supply the gas from the introduction tube 103 as a gas. This is because the decomposition of hydrogen is difficult to proceed, and the carbon film contains a large amount of polymer components having inferior strength.

  Furthermore, in the present invention, in order to induce the generation of plasma in the film formation chamber 101, it is preferable to use a mixed gas in which an inert gas, a hydrogen gas, or the like is contained in the raw material gas G containing carbon. The mixing ratio of the hydrocarbon and the inert gas in the mixed gas is preferably set to a range of 2: 1 to 1: 100 (volume ratio) of hydrocarbon: inert gas. A highly durable carbon film can be formed.

  As described above, in the present invention, it is possible to suppress deformation during film formation of the filamentary cathode electrode 104 by performing carbonization while rotating the cathode electrode 104 in advance. Therefore, when the carbon film is formed using the carbonized cathode electrode 104, the life of the cathode electrode 104 can be increased as compared with the conventional case.

  In the present invention, in the film forming apparatus using such an ion beam evaporation method, a raw material gas G containing carbon is introduced into the decompressed film forming chamber 101, and the raw material gas G is heated by energization. When the ionized gas is ionized by discharge between the filamentary cathode electrode 104 and the anode electrode 105 provided around the cathode electrode 104 and the surface of the substrate D is accelerated and irradiated, a magnetic field is applied from the outside. Accordingly, it is possible to increase the ion density of the ionized gas that is accelerated and irradiated toward the surface of the substrate D, and to form a high hardness and dense carbon film on the surface of the substrate D.

  Furthermore, in the present invention, even when the carbon film is formed, by rotating the cathode electrode 104, it is possible to make the film thickness distribution in the plane of the carbon film deposited on the surface of the substrate D more uniform. is there.

  In the carbon film forming apparatus shown in FIG. 1, the carbon film is formed only on one surface of the substrate D. However, the carbon film can be formed on both surfaces of the substrate D. It is. In this case, an apparatus configuration similar to that in the case where a carbon film is formed only on one surface of the substrate D may be disposed on both sides of the substrate D in the film formation chamber 101.

(Method of manufacturing magnetic recording medium)
Next, a method for manufacturing a magnetic recording medium to which the present invention is applied will be described.
In the present embodiment, a magnetic recording medium mounted on a hard disk device is manufactured using an in-line film forming apparatus that performs film forming processing while sequentially transferring a substrate to be formed between a plurality of film forming chambers. A case will be described as an example.

(Magnetic recording medium)
A magnetic recording medium manufactured by applying the present invention has a soft magnetic layer 81, an intermediate layer 82, a recording magnetic layer 83, and a protective layer 84 sequentially stacked on both surfaces of a nonmagnetic substrate 80, for example, as shown in FIG. Further, a lubricating film 85 is formed on the outermost surface. The soft magnetic layer 81, the intermediate layer 82 and the recording magnetic layer 83 constitute a magnetic layer 810.

  In this magnetic recording medium, a high-hardness and dense carbon film is formed as the protective layer 84 by using the carbon film forming method to which the present invention is applied. In this case, in the magnetic recording medium, the film thickness of the carbon film can be reduced. Specifically, the film thickness of the carbon film can be about 2 nm or less.

  Therefore, in the present invention, it is possible to set the distance between the magnetic recording medium and the magnetic head narrow, and as a result, the recording density of the magnetic recording medium is increased and the corrosion resistance of the magnetic recording medium is increased. It is possible to increase.

Hereinafter, each layer other than the protective layer 84 of the magnetic recording medium will be described.
The nonmagnetic substrate 80 is made of an Al alloy substrate such as an Al—Mg alloy mainly composed of Al, ordinary soda glass, aluminosilicate glass, crystallized glass, silicon, titanium, ceramics, and various resins. Any substrate can be used as long as it is a non-magnetic substrate.

  Among them, it is preferable to use an Al alloy substrate, a glass substrate such as crystallized glass, and a silicon substrate, and the average surface roughness (Ra) of these substrates is preferably 1 nm or less, more preferably It is 0.5 nm or less, and among these, 0.1 nm or less is particularly preferable.

The magnetic layer 810 may be an in-plane magnetic layer for an in-plane magnetic recording medium or a perpendicular magnetic layer for a perpendicular magnetic recording medium, but a perpendicular magnetic layer is preferable in order to achieve a higher recording density. The magnetic layer 810 is preferably formed from an alloy mainly composed of Co. For example, as the magnetic layer 810 for a perpendicular magnetic recording medium, for example, soft magnetic FeCo alloys (FeCoB, FeCoSiB, FeCoZr, FeCoZrB, FeCoZrBCu, etc.), FeTa alloys (FeTaN, FeTaC, etc.), Co alloys (CoTaZr, CoZrNB, CoB) Etc.), an intermediate layer 82 made of Ru, etc., and a recording magnetic layer 83 made of 60Co-15Cr-15Pt alloy or 70Co-5Cr-15Pt-10SiO ₂ alloy can be used. . Further, an orientation control film made of Pt, Pd, NiCr, NiFeCr or the like may be laminated between the soft magnetic layer 81 and the intermediate layer 82. On the other hand, as the magnetic layer 810 for the in-plane magnetic recording medium, a laminate of a nonmagnetic CrMo underlayer and a ferromagnetic CoCrPtTa magnetic layer can be used.

  The total thickness of the magnetic layer 810 is 3 nm or more and 20 nm or less, preferably 5 nm or more and 15 nm or less. The magnetic layer 810 can obtain sufficient head input / output according to the type of magnetic alloy used and the laminated structure. What is necessary is just to form. The film thickness of the magnetic layer 810 requires a certain thickness of the magnetic layer in order to obtain a certain level of output during reproduction, while parameters indicating recording / reproduction characteristics deteriorate as the output increases. Therefore, it is necessary to set an optimum film thickness.

  As the lubricant used for the lubricating film 85, a fluorinated liquid lubricant such as perfluoroether (PFPE) and a solid lubricant such as fatty acid can be used. Usually, the lubricating layer 85 is formed with a thickness of 1 to 4 nm. As a method for applying the lubricant, a conventionally known method such as a dipping method or a spin coating method may be used.

  As another magnetic recording medium manufactured by applying the present invention, for example, as shown in FIG. 4, a magnetic recording pattern 83a formed on the recording magnetic layer 83 is separated by a nonmagnetic region 83b. A so-called discrete type magnetic recording medium may also be used.

  As for the discrete type magnetic recording medium, a so-called patterned medium in which the magnetic recording pattern 83a is arranged with a certain regularity for each bit, a medium in which the magnetic recording pattern 83a is arranged in a track shape, and the like, The magnetic recording pattern 83a may include a servo signal pattern or the like.

  In such a discrete type magnetic recording medium, a mask layer is provided on the surface of the recording magnetic layer 83, and a portion not covered with the mask layer is exposed to a reactive plasma treatment, an ion irradiation treatment, or the like. This is obtained by modifying a part of the magnetic material from a magnetic material to a nonmagnetic material to form a nonmagnetic region 83b.

(Magnetic recording / reproducing device)
An example of the magnetic recording / reproducing apparatus using the magnetic recording medium is a hard disk apparatus as shown in FIG. This hard disk device includes a magnetic disk 96 that is the magnetic recording medium, a medium driving unit 97 that rotationally drives the magnetic disk 96, a magnetic head 98 that records and reproduces information on the magnetic disk 96, a head driving unit 99, and a recording medium. A reproduction signal processing system 100. Then, the magnetic reproduction signal processing system 100 processes the input data, sends a recording signal to the magnetic head 98, processes the reproduction signal from the magnetic head 98, and outputs the data.

  When the magnetic recording medium is manufactured, for example, an in-line film forming apparatus (magnetic recording medium manufacturing apparatus) to which the present invention is applied as shown in FIG. In addition, the magnetic layer 810 including at least the soft magnetic layer 81, the intermediate layer 82, and the recording magnetic layer 83, and the protective layer 84 are sequentially laminated, so that the magnetic layer including the high-hardness and dense carbon film as the protective layer 84 is provided. A recording medium can be manufactured stably.

(In-line deposition system)
Specifically, an in-line type film forming apparatus to which the present invention is applied includes a robot stand 1, a substrate cassette transfer robot 3 placed on the robot stand 1, a substrate supply robot chamber 2 adjacent to the robot stand 1, The substrate supply robot 34 disposed in the substrate supply robot chamber 2, the substrate mounting chamber 52 adjacent to the substrate supply robot chamber 2, corner chambers 4, 7, 14, 17 for rotating the carrier 25, and each corner chamber 4, 7, 14, 17, processing chambers 5, 6, 8-13, 15, 16, 18-20, substrate removal chamber 54 positioned adjacent to processing chamber 20, and substrate attachment The ashing chamber 3A disposed between the chamber 52 and the substrate removal chamber 54, the substrate removal robot chamber 22 disposed adjacent to the substrate removal chamber 54, and the substrate removal robot chamber 22 It is schematically configured to have the substrate removal robot 49 installed, and a plurality of carriers 25 to be transported between these chambers to.

  In addition, each chamber 2, 52, 4-20, 54, 3A is connected to two adjacent walls, respectively, and in the connecting portion of each chamber 2, 52, 4-20, 54, 3A, When the gate valves 55 to 71 are provided and these gate valves 55 to 71 are closed, each room becomes an independent sealed space.

  Also, each chamber 2, 52, 4-20, 54, 3A is connected to a vacuum pump (not shown), and is transported to each chamber that has been decompressed by the operation of these vacuum pumps. While sequentially transporting the carrier 25 by a mechanism (not shown), the soft magnetic layer 81, the intermediate layer 82, and the recording magnetic layer 83 described above are formed on both surfaces of the nonmagnetic substrate 80 mounted on the carrier 25 in each room. 3 and the protective layer 84 are sequentially formed, so that the magnetic recording medium shown in FIG. 3 is finally obtained. Each corner chamber 4, 7, 14, 17 is a chamber for changing the moving direction of the carrier 25, and a mechanism for rotating the carrier 25 to move to the next film forming chamber is provided therein.

  The substrate cassette transfer robot 3 supplies the nonmagnetic substrate 80 to the substrate mounting chamber 2 from the cassette in which the nonmagnetic substrate 80 before film formation is stored, and removes the nonmagnetic film after film formation removed in the substrate removal chamber 22. The magnetic substrate 80 (magnetic recording medium) is taken out. An opening opened to the outside and 51 and 55 for opening and closing the opening are provided on one side wall of the substrate attaching / detaching chambers 2 and 22.

  Inside the substrate mounting chamber 52, the nonmagnetic substrate 80 before film formation is mounted on the carrier 25 using the substrate supply robot 34. On the other hand, inside the substrate removal chamber 54, the non-magnetic substrate 80 (magnetic recording medium) after film formation mounted on the carrier 25 is removed using the substrate removal robot 49. The ashing chamber 3 </ b> A ashes the carrier 25 transported from the substrate removal chamber 54 and then transports the carrier 25 to the substrate mounting chamber 52.

  Among the processing chambers 5, 6, 8 to 13, 15, 16, and 18 to 20, a plurality of film forming chambers for forming the magnetic layer 810 are formed by the processing chambers 5, 6, 8 to 13, 15, and 16. It is configured. These film forming chambers have a mechanism for forming the above-described soft magnetic layer 81, intermediate layer 82, and recording magnetic layer 83 on both surfaces of the nonmagnetic substrate 80.

  On the other hand, a film forming chamber for forming the protective layer 84 is constituted by the processing chambers 18 to 20. These film forming chambers have the same apparatus configuration as the film forming apparatus using the ion beam evaporation method shown in FIG. 1, and a protective layer 84 is formed on the surface of the nonmagnetic substrate 80 on which the magnetic layer 810 is formed. The above-described high hardness and dense carbon film is formed.

  When the magnetic recording medium shown in FIG. 4 is manufactured, the processing chamber further includes a patterning chamber for patterning the mask layer and a portion of the recording magnetic layer 83 that is not covered with the patterned mask layer. On the other hand, a reactive plasma treatment or ion irradiation treatment is performed to modify a part of the recording magnetic layer 83 from a magnetic material to a nonmagnetic material, thereby forming a magnetic recording pattern 83b separated by a nonmagnetic region 83b. A modification chamber and a removal chamber for removing the mask layer may be added.

  Each processing chamber 5, 6, 8-13, 15, 16, 18-20 is provided with a processing gas supply pipe, and the supply pipe is provided with a valve whose opening and closing is controlled by a control mechanism (not shown). By opening and closing these valves and the pump gate valve, the supply of gas from the processing gas supply pipe, the pressure in the chamber, and the discharge of the gas are controlled.

  As shown in FIGS. 7 and 8, the carrier 25 includes a support base 26 and a plurality of substrate mounting portions 27 provided on the upper surface of the support base 26. In the present embodiment, since the two substrate mounting portions 27 are mounted, the two nonmagnetic substrates 80 mounted on the substrate mounting portion 27 are respectively connected to the first film-forming substrate 23 and the second component. Assume that it is handled as the film substrate 24.

  The substrate mounting portion 27 is slightly larger than the outer periphery of the film forming substrates 23 and 24 on the plate body 28 having a thickness of about 1 to several times the thickness of the first and second film forming substrates 23 and 24. A circular through hole 29 having a diameter is formed, and a plurality of support members 30 projecting toward the inside of the through hole 29 are provided around the through hole 29. The first and second film formation substrates 23 and 24 are fitted into the substrate mounting portion 27 in the through hole 29, and the support member 30 is engaged with the edge portion thereof, whereby the film formation substrate 23 is formed. , 24 are held vertically (the main surfaces of the substrates 23, 24 are parallel to the direction of gravity). That is, the substrate mounting portion 27 is configured so that the main surfaces of the first and second film-forming substrates 23 and 24 mounted on the carrier 25 are substantially orthogonal to the upper surface of the support base 26 and are substantially on the same surface. As shown in the figure, it is provided in parallel with the upper surface of the support base 26.

  Further, the processing chambers 5, 6, 8 to 13, 15, 16, and 18 to 20 described above have two processing apparatuses on both sides of the carrier 25. In this case, for example, in a state where the carrier 25 is stopped at the first processing position indicated by the solid line in FIG. 7, a film forming process is performed on the first film forming substrate 23 on the left side of the carrier 25, and then In a state where the carrier 25 moves to the second processing position indicated by the broken line in FIG. 7 and the carrier 25 stops at the second processing position, the film forming process is performed on the second film forming substrate 24 on the right side of the carrier 25. Etc. can be performed.

  If there are four processing apparatuses facing the first and second film-forming substrates 23 and 24 on both sides of the carrier 25, the carrier 25 does not need to be moved, and the first is held by the carrier 25. A film forming process or the like can be simultaneously performed on the first and second film forming substrates 23 and 24.

After the film formation, the first and second film formation substrates 23 and 24 are removed from the carrier 25, and only the carrier 25 on which the carbon film is deposited is transferred into the ashing chamber 3A. Then, oxygen gas is introduced from an arbitrary portion of the ashing chamber 3A, and oxygen plasma is generated in the ashing chamber 3A using this oxygen gas. When the oxygen plasma comes into contact with the carbon film deposited on the surface of the carrier 25, the carbon film is decomposed into CO or CO ₂ gas and removed.

  Hereinafter, the effects of the present invention will be made clearer by examples. In addition, this invention is not limited to a following example, In the range which does not change the summary, it can change suitably and can implement.

Example 1
In Example 1, carbonization of a filament (cathode electrode) made of tantalum was performed prior to the formation of the carbon film. This filament is a 0.3 mm diameter tantalum wire (purity 99.9% or more) processed into a linear coil shape with an inner diameter of 10 mm, a length of 30 mm, and a number of turns of 3, and this is set in a chamber. The cathode electrode was carbonized while the cathode electrode was rotated at 60 rpm by heating and heating for 10 minutes under the conditions of gasified toluene of 2.9 SCCM, carbonization pressure of 0.2 Pa, and cathode power of 225 W (AC 22.5 V, 10 A). By processing, a filament made of tantalum carbide was obtained. The carbonized filament was almost straight without sagging.

Then, a carbon film on the surface of the magnetic recording medium was continuously formed using this cathode electrode. Specifically, first, an aluminum substrate on which NiP plating was applied was prepared as a nonmagnetic substrate. Next, using the in-line film forming apparatus shown in FIG. 6, a soft magnetic layer made of FeCoB having a film thickness of 60 nm and a film thickness of 10 nm are formed on both surfaces of a nonmagnetic substrate mounted on an A5052 aluminum alloy carrier. A magnetic layer was formed by sequentially laminating an intermediate layer made of Ru and a recording magnetic layer made of 70Co-5Cr-15Pt-10SiO ₂ alloy having a thickness of 15 nm. Next, the nonmagnetic substrate mounted on the carrier is transferred to a processing chamber having the same apparatus configuration as the film forming apparatus shown in FIG. 1, and is formed of carbon films on both surfaces of the nonmagnetic substrate on which the magnetic layer is formed. A protective layer was formed.

  The processing chamber has a cylindrical shape with an outer diameter of 180 mm and a length of 250 mm, and the material of the chamber wall constituting the processing chamber is SUS304. In the processing chamber, there are provided a cathode electrode subjected to the above carbonization treatment and a cylindrical anode electrode surrounding the cathode electrode. The anode electrode is made of SUS304, has an outer diameter of 140 mm, and a length of 40 mm. The distance between the cathode electrode and the nonmagnetic substrate was 160 mm. Furthermore, a cylindrical magnet surrounding the periphery of the chamber wall was arranged so that the anode electrode was positioned at the center. The magnet has an inner diameter of 185 mm and a length of 40 mm. Inside, as shown in FIG. 2 (a), an NdFe-based sintered bar magnet having a 10 mm square and a length of 40 mm is arranged in parallel at equal intervals. In addition to the actual arrangement, the sintered bar magnets were arranged so that the S pole was on the substrate side and the N pole was on the cathode electrode side. The total magnetic force of this magnet is 50 G (5 mT).

  As the source gas, gasified toluene was used. As for the carbon film deposition conditions, the gas flow rate is 2.9 SCCM, the reaction pressure is 0.2 Pa, the cathode power is 225 W (AC 22.5 V, 10 A), the voltage between the cathode electrode and the anode electrode is 75 V, and the current Was 1650 mA, the acceleration voltage of ions was 200 V, 180 mA, and the carbon film thickness was 3.5 nm. Note that the cathode electrode was not rotated when the carbon film was formed.

  Then, the film formation time per substrate is about 3.6 seconds, and after the carbon film is formed, the time for transporting the next substrate is about 1 second. Under these conditions, continuous film formation for 6 days (144 hours) is performed. went. As a result, in the cathode electrode after continuous film formation, although the central portion of the filament hangs down by about 7 mm, the in-plane distribution of the carbon film on the surface of the magnetic recording medium is ± 7% or less, which is sufficiently acceptable. Met.

(Example 2)
In Example 2, a carbon film is continuously formed under the same conditions as in Example 1 using the same carbonized cathode electrode as in Example 1, and the cathode electrode is kept at 5 rpm during carbon film formation. Rotated. As a result, in the cathode electrode after continuous film formation, although the central part of the filament hangs down by about 2 mm, the in-plane distribution of the carbon film on the surface of the magnetic recording medium is ± 3% or less, which is sufficiently acceptable. It was.

(Comparative Example 1)
In Comparative Example 1, the cathode electrode was carbonized and the carbon film was continuously formed under the same conditions as in Example 1 except that the cathode electrode was not rotated during carbonization. Moreover, the linear filament was arrange | positioned in parallel with the ground surface at the time of carbonization processing. As a result, in the cathode electrode after the carbonization treatment, the central part of the filament was hung downward by about 4 mm. In addition, when continuous film formation was performed for 6 days using the filament in this state, the cathode electrode after the continuous film formation had a central portion of the filament hanging downward by about 13 mm, and the carbon film on the surface of the magnetic recording medium was in-plane. The distribution was ± 12%.

DESCRIPTION OF SYMBOLS 1 ... Substrate cassette transfer robot stand 2 ... Substrate supply robot chamber 3 ... Substrate cassette transfer robot 3A ... Ashing chamber 4, 7, 14, 17 ... Corner chamber 5, 6, 8-13, 15, 16, 18-20 ... Processing chamber 22 ... Substrate removal robot chamber 23 ... First film forming substrate 24 ... Second film forming substrate 25 ... Carrier 26 ... Support base 27 ... Substrate mounting portion 28 ... Plate body 29 ... Circular through hole 30 ... Support member 34 ... Substrate supply robot 49 ... Substrate removal robot 52 ... Substrate attachment chamber 54 ... Substrate removal chamber 80 ... Nonmagnetic substrate 81 ... Soft magnetic layer 82 ... Intermediate layer 83 ... Recording magnetic layer 84 ... Protective layer 85 ... Lubrication film 810 ... magnetic layer 101 ... deposition chamber 102 ... holder 103 ... introducing tube 104 ... cathode electrode 105 ... anode electrode 106 ... first power source 107 ... second power source 108 ... third power source 109 ... ma Net 110 ... exhaust pipe 120 ... drive mechanism 121 ... rotary plate 122 ... driving motor 123 ... cable terminal

Claims (9)

The raw material gas containing carbon is introduced into the decompressed film formation chamber, and this gas is ionized by discharge between the filament-shaped cathode electrode heated by energization and the anode electrode provided around the gas. A method of forming a carbon film by accelerating the irradiated gas and irradiating the surface of the substrate with a carbon film on the surface of the substrate,
A carbon film forming method, wherein after carbonizing the cathode electrode while rotating, the carbon film is formed using the carbonized cathode electrode.   2. The carbon film forming method according to claim 1, wherein a filament made of tantalum is used as the cathode electrode, and the filament is carbonized while rotating the filament to form a filament made of tantalum carbide.   The carbon film forming method according to claim 1, wherein the cathode electrode is rotated during the carbonization treatment.   The carbonization time is in the range of 5 to 30 minutes, the number of rotations of the cathode electrode during the carbonization is in the range of 1 to 100 rpm, and the total carbon film formation time after the carbonization is 50 hours or more. The method for forming a carbon film according to claim 3, wherein:   The method for forming a carbon film according to claim 1, wherein the cathode electrode is rotated when the carbon film is formed.   The method for forming a carbon film according to claim 1, wherein a magnet for applying a magnetic field is disposed in a region for ionizing the raw material gas or a region for accelerating the ionized gas.   The method of forming a carbon film according to claim 6, wherein a magnetic field is applied so that an acceleration direction of the ionized gas is parallel to a direction of a line of magnetic force generated by the magnet.   The surface of the substrate is irradiated while accelerating the ionized gas by providing a potential difference between the cathode electrode or the anode electrode and the substrate. A method for forming the carbon film according to the description.   A carbon film is formed on a nonmagnetic substrate on which at least a magnetic layer is formed by using the method for forming a carbon film according to claim 1. Method.

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