JP2015032335A - Method for manufacturing carbon film, magnetic recording medium and magnetic storage device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for manufacturing a carbon film, capable of obtaining the carbon film having high wettability to a lubricant and high hardness and including hydrogen.SOLUTION: The method for manufacturing a carbon film comprises the steps of: forming the carbon film including hydrogen on the surface of a base material; and ionizing a mixed gas of nitrous oxide and nitrogen and emitting the ions on the surface of the carbon film including hydrogen. The amount of the nitrous oxide included in the mixed gas of the nitrous oxide and the nitrogen is 1-80 volume%, and the ions are accelerated and emitted on the surface of the carbon film including hydrogen.

Description

  The present invention relates to a carbon film manufacturing method, a magnetic recording medium manufactured using the carbon film, and a magnetic storage device.

  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 and read / write speed 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 as the protective film of the magnetic recording medium is formed by a sputtering method, a CVD method, an ion beam evaporation method, 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.

  For example, Patent Document 1 discloses that a film forming material gas is brought into a plasma state by a discharge between a heated filament cathode and anode in a film forming chamber under a vacuum condition, and this is accelerated and collided with a negative potential substrate surface. Thus, a hot filament-plasma CVD apparatus is disclosed in which thickness variation is suppressed and a carbon film is stably formed.

  A diamond film and a diamond-like carbon (DLC) film are known as a hard carbon film formed by the above-described CVD method or ion beam evaporation method. The diamond film is generally a polycrystalline film with approximately 100% diamond bonding. The DLC film is an amorphous hard carbon film. Here, since the carbon film used for the protective film of the magnetic recording medium is required to have a high surface smoothness, a DLC film is generally used without using a crystalline diamond film. A hydrogenated DLC film (carbon film containing hydrogen) is used.

  However, the protection of the magnetic recording medium is not sufficient only by providing a protective film, and a lubricant layer having a thickness of about 0.5 to 3 nm is applied to the surface of the protective film to form a lubricant layer. Improves membrane durability and protection. Thus, by providing the lubricant layer, the magnetic head (magnetic head slider) can be prevented from coming into direct contact with the protective film, and the magnetic head (magnetic head slider) sliding on the magnetic recording medium can be prevented. Thus, it is possible to remarkably reduce the frictional force of the magnetic recording medium, so that it is possible to prevent contaminants from entering the magnetic recording medium.

Here, as the lubricant, a perfluoropolyether lubricant, an aliphatic hydrocarbon lubricant and the like have been proposed. For example, Patent Document _{2, HOCH 2 - {CF 2} (OC 2 F 4) m - (OCF 2) n -OCF 2} -CH 2 OH (m, n are integers) perfluoroalkyl poly having a structure of A magnetic recording medium coated with an ether lubricant is disclosed.

Further, Patent Document _{3, HOCH 2 CH (OH)} -CH 2 OCH 2 CF 2 O- (C 2 F 4 O) m - (CF 2 O) n -CF 2 CH 2 OCH 2 -CH (OH) A magnetic recording medium having a lubricating layer made of perfluoroalkyl polyether (tetraol) having a structure of CH ₂ OH (m and n are integers) is disclosed.

  By the way, the hydrogenated DLC film contains about 20 atomic% of hydrogen. Such a DLC film having a high hydrogen content has a lower hardness than a DLC film that does not contain any hydrogen, and a lubricant (for example, a fluorocarbon such as perfluoroether (PFPE)) applied on the DLC film. The wettability with respect to the liquefied liquid lubricant) is poor and the coverage of the lubricant on the DLC film is reduced.

With regard to such problems, Patent Document 4 discloses that a protective film mainly composed of carbon that protects the magnetic film is formed by an ion beam method or chemical vapor deposition in order to increase the chemical bonding force between the protective film layer and the liquid lubricant. It is disclosed that N ₂ O gas is added when forming a film by the position method.

JP 2000-226659 A JP 11-49716 A JP-A-9-282642 JP 2002-109718 A

  However, according to the study of the inventors of the present invention, when the film formation method disclosed in Patent Document 4 is adopted when forming the carbon film, the density of the carbon film itself is reduced, and the hardness of the carbon film is further increased. It was revealed that the function as a protective film may not be sufficiently achieved.

  The present invention has been made in view of the above-described problems of the prior art, and an object of the present invention is to provide a method for producing a carbon film that provides a carbon film containing hydrogen having high wettability to a lubricant, high hardness, and high surface smoothness. .

  The inventor of the present application has completed the following invention as a result of studies to solve the above-described problems.

(1) A step of forming a carbon film containing hydrogen on the surface of the substrate, a step of ionizing a mixed gas of nitrous oxide and nitrogen, and irradiating the surface of the carbon film containing hydrogen with ions formed by the ionization A process for producing a carbon film.

(2) The method for producing a carbon film according to (1), wherein the amount of nitrous oxide contained in the mixed gas is in the range of 1% by volume to 80% by volume.

(3) In the step of irradiating the surface of the carbon film containing hydrogen with the ions, the ions according to (1) or (2) are irradiated after accelerating the ions and then irradiating the surface of the carbon film containing hydrogen. A method for producing a membrane.

(4) A step of forming a carbon film containing hydrogen on the surface of the substrate includes a step of introducing a raw material gas containing carbon and hydrogen into a film forming chamber, a step of ionizing the raw material gas, and accelerating the ions. And irradiating the surface of the substrate with the method of producing a carbon film according to any one of (1) to (3).

(5) a substrate, a magnetic layer provided on at least one surface side of the substrate, a carbon film containing hydrogen provided on a surface of the magnetic layer opposite to the surface facing the substrate, The carbon film containing hydrogen has a hydrogen concentration on the surface opposite to the surface facing the magnetic layer lower than the highest hydrogen concentration in the film, and the carbon film containing hydrogen is at least the A magnetic recording medium in which a surface opposite to a surface facing a magnetic layer is nitrided.

(6) A magnetic storage device having the magnetic recording medium according to (5).

  ADVANTAGE OF THE INVENTION According to this invention, the manufacturing method of the carbon film from which the wettability with respect to a lubricant is high, and the carbon film containing hydrogen with high hardness and high smoothness is obtained can be provided.

The block diagram of the formation apparatus of the carbon film containing hydrogen in the 1st Embodiment of this invention. FIG. 6 is a cross-sectional configuration diagram of a magnetic recording medium according to a second embodiment of the present invention. The block diagram of the magnetic memory device in the 3rd Embodiment of this invention.

  DESCRIPTION OF EMBODIMENTS Hereinafter, embodiments for carrying out the present invention will be described. However, the present invention is not limited to the following embodiments, and various modifications and changes can be made to the following embodiments without departing from the scope of the present invention. Substitutions can be added.

[First Embodiment]
A configuration example of the carbon film manufacturing method of the present embodiment will be described.
The method for producing a carbon film according to the present embodiment includes a step of forming a carbon film containing hydrogen on the surface of a substrate, and ionizing a mixed gas of nitrous oxide and nitrogen, and this ion is applied to the surface of the carbon film containing hydrogen. And irradiating.
Each step will be described below.

(Process of forming a carbon film containing hydrogen on the surface of the substrate)
First, the process of forming a carbon film containing hydrogen on the surface of the substrate will be described.
The method for forming the carbon film containing hydrogen in this step is not particularly limited, and various known methods can be used. For example, a CVD method (chemical vapor deposition method) using hydrocarbon gas as a raw material, a PVD method (physical vapor deposition method) exemplified by ion beam deposition method, a hydrocarbon gas is added to an inert gas, and a carbon target is used. It can be formed by a reactive sputtering method or the like. Among these film formation methods, a carbon film having a low hydrogen concentration, high hardness, and high smoothness can be formed as compared with other film formation methods, so that ion beam evaporation can be preferably used. .
Hereinafter, a method for forming a carbon film containing hydrogen will be described as an example in which an ion beam deposition method is used as the film formation method.
FIG. 1 shows a configuration example of an apparatus for forming a carbon film containing hydrogen using an ion beam deposition method.

  As shown in FIG. 1, the apparatus for forming a carbon film containing hydrogen includes a deposition chamber 101 that can be depressurized, and a holder 102 that holds a substrate D in the deposition chamber 101 is provided. The film forming chamber 101 is provided with an introduction pipe 103 for introducing a source gas G containing carbon and hydrogen (hereinafter also referred to as “gas G”) and an inert gas. Further, it has a filament-like cathode electrode 104 arranged in the film formation chamber 101 and an anode electrode 105 arranged around the cathode electrode 104 in the film formation chamber 101. Then, the first power source 106 that heats the cathode electrode 104 by energization, the second power source 107 that generates a discharge between the cathode electrode 104 and the anode electrode 105, the cathode electrode 104 or the anode electrode 105, and the substrate D And a third power source 108 for providing a potential difference between the first and second power sources. Further, a magnet 109 for applying a magnetic field between the cathode electrode 104 and the anode electrode 105 or the substrate D is provided.

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

  The first power source 106 is a power source connected to the cathode electrode 104 and supplies power to the cathode electrode 104 when a carbon film containing hydrogen is formed. In the figure, the first power source 106 is shown as an AC power source, but 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 is formed between the cathode electrode 104 and the anode electrode 105 when the carbon film containing hydrogen is formed. Causes a discharge.

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

The magnet 109 is preferably made of a permanent magnet or an electromagnet, and is preferably arranged around the chamber wall 101a and can be rotationally driven in the circumferential direction by a drive motor (not shown). 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.

  Here, the rotation of the magnet 109 in the present embodiment refers to a case where the magnet 109 is continuously rotated in one direction beyond an angle of 360 ° and is reciprocally rotated (oscillated) at an angle of less than 360 °. Including. For example, when a plurality of bar magnets are arranged as the magnet 109 in parallel with the central axis of rotation at equal intervals, when the shortest interval between the bar magnets makes X ° with respect to the central axis, reciprocating rotation ( The angle range to be swung) can be set to X °. Thereby, the magnetic field generated in the film formation chamber 101 can be made uniform. In addition, when an electromagnet is used, it is necessary to supply electric power, and therefore, it is preferable to perform reciprocal rotation at an angle of 180 ° to less than 360 °.

  Depending on the size of the base material D, when using a disk-shaped substrate having an outer diameter of 3.5 inches as the base material D and forming a carbon film containing hydrogen on the surface thereof, the first power source 106 is It is preferable to set the voltage in a range of 10 to 100 V and the current in a range of 5 to 50 A by direct current or alternating current. For the second power source 107, it is preferable to set the voltage in the range of 50 to 300V and the current in the range of 10 to 5000mA. For the third power source 108, the voltage is in the range of 30 to 500V and the current is It is preferable to set in the range of 10 to 200 mA. About the rotation speed of the magnet 109, it is preferable to set in the range of 20-200 rpm, for example.

When performing the process of forming the carbon film containing hydrogen on the surface of the base material D using the forming apparatus configured as described above, for example, the following procedure can be used. In this case, the substrate D is not particularly limited, and a substrate on which no other layer is formed as described above can be used, and another layer is already formed on the substrate surface. Can also be used. For example, when a carbon film containing hydrogen is formed on the surface of the magnetic layer as described later, the substrate on which the magnetic layer is formed is used as the base material D.
First, a raw material gas G containing carbon and hydrogen is introduced into the film forming chamber 101, which has been decompressed via the exhaust pipe 110, via the introduction pipe 103.

  The raw material gas G is generated by discharge between the thermal plasma of the cathode electrode 104 heated by the power supply from the first power source 106 and the cathode electrode 104 and the anode electrode 105 connected to the second power source 107. The plasma is excited and decomposed by the plasma. Thereby, the gas G of the raw material is converted into an ionized gas (carbon ion).

  The carbon ions excited in the plasma preferably collide with the surface of the base material D while accelerating toward the base material D, which is set to a negative potential by the third power source 108.

  That is, the step of forming the carbon film containing hydrogen on the surface of the substrate was ionized, the step of introducing a source gas (gas G) containing carbon and hydrogen into the deposition chamber, the step of ionizing the source gas, It is preferable to have a step of accelerating the raw material gas and irradiating the surface of the substrate.

  Here, in the method for forming a carbon film containing hydrogen according to the present embodiment, a region in which the source gas G is ionized or an ionized gas (referred to as an ion beam) by the magnet 109 disposed around the chamber wall 101a. It is preferable to apply a magnetic field in a region to be accelerated (hereinafter referred to as “excitation space”). Thus, when accelerating and irradiating the surface of the substrate D with carbon ions, the ion density of the carbon ions that are accelerated and irradiated toward the surface of the substrate D can be increased by applying a magnetic field from the outside. it can.

  As a result, when the ion density in the excitation space is increased, the excitation force in the excitation space is increased, and the surface of the substrate D can be acceleratedly irradiated with carbon ions in a higher energy state. For this reason, it becomes possible to form a carbon film containing hydrogen having a particularly high hardness and a particularly high density on the surface of the substrate D. Further, a carbon film containing hydrogen with high smoothness can be obtained.

  Furthermore, in the present invention, by rotating the magnet 109 arranged around the excitation space in the circumferential direction, the distribution of the magnetic field applied to the excitation space is made uniform, and the distribution of carbon ions in the excitation space is made uniform. Can be made uniform and the surface of the substrate D can be irradiated. Therefore, the film thickness distribution of the carbon film containing hydrogen formed on the surface of the substrate D can be stabilized.

  Here, the raw material gas G containing carbon and hydrogen is not particularly limited, but for example, a gas containing hydrocarbon can be preferably used. As the hydrocarbon, it is preferable to use one or more low-carbon hydrocarbons selected from 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, as the lower saturated hydrocarbon, for example, methane, ethane, propane, butane, octane and the like can be preferably used. On the other hand, as the lower unsaturated hydrocarbon, for example, isoprene, ethylene, propylene, butylene, butadiene and the like can be used. On the other hand, as the lower cyclic hydrocarbon, for example, benzene, toluene, xylene, styrene, naphthalene, cyclohexane, cyclohexadiene, adamantane and the like can be preferably used.

As described above, the step of forming the carbon film containing hydrogen on the surface of the substrate can be preferably performed using a film forming apparatus using such an ion beam evaporation method.
The carbon film containing hydrogen formed at this time is not particularly limited, but is preferably a DLC film.

(Step of ionizing a mixed gas of nitrous oxide and nitrogen and irradiating the surface of the carbon film containing hydrogen)
Next, a process of ionizing a mixed gas of nitrous oxide and nitrogen and irradiating the surface of the carbon film containing hydrogen will be described.
This step can be performed, for example, according to the following procedure.

  First, after forming a carbon film containing hydrogen, a mixed gas of nitrous oxide and nitrogen is introduced into the deposition chamber 101. The mixed gas is ionized by discharge between the filament-shaped cathode electrode 104 heated by energization and the anode electrode 105 provided around the cathode electrode 104. Subsequently, this ion is irradiated to the carbon film containing hydrogen formed on the surface of the base material D, and at least the surface layer portion of the carbon film containing hydrogen is ejected by the irradiated ions, and the surface layer portion is nitrided.

  In the present invention, a mixed gas of nitrous oxide and nitrogen is used to form ions that irradiate the carbon film containing hydrogen. Since nitrous oxide gas has lower dissociation energy than oxygen gas and nitrogen gas, it is easy to form oxygen ions and nitrogen ions, and the mass of the formed ions is small, so that the structure of the carbon film itself is rarely broken. For this reason, the surface of the carbon film containing hydrogen is ionized with a mixed gas of nitrous oxide and nitrogen and irradiated with these ions, so that the structure of the lower layer of the carbon film containing hydrogen is not broken, and therefore the carbon containing hydrogen While maintaining high surface smoothness of the film, only hydrogen in the surface layer portion of the carbon film containing hydrogen can be efficiently ejected and nitridation can be performed efficiently.

  As described above, the production method of the present invention has the effect of extruding at least the surface layer hydrogen of the carbon film containing hydrogen by the oxidizing action of oxygen ions and nitriding the surface layer portion with nitrogen ions. In order to achieve this effect, it is considered that only nitrous oxide containing oxygen and nitrogen atoms may be ionized and used. However, in nitrous oxide, since the atomic ratio of oxygen to nitrogen is fixed at 1: 2, it is difficult to adjust the oxidizing action of oxygen ions and the nitriding action of nitrogen ions in a well-balanced manner. In particular, according to the study by the inventors of the present invention, when hydrogen is ejected and nitrided on the surface of the carbon film containing hydrogen using ions formed only from nitrous oxide, the nitriding effect is weaker than the effect of ejecting hydrogen. It became clear.

  Accordingly, the present invention aims to enhance the nitriding effect in the surface layer portion of the carbon film containing hydrogen by using a mixed gas of nitrous oxide and nitrogen to form ions irradiated to the carbon film containing hydrogen. .

  The amount of nitrous oxide contained in the mixed gas of nitrous oxide and nitrogen used in the present invention depends on various conditions such as the degree of hydrogenation of the carbon film to be processed, the density, the structure of the processing apparatus, and the processing pressure. However, it is preferably in the range of 1 vol% to 80 vol%, more preferably in the range of 1.5 vol% to 60 vol%, most preferably in the range of 2 vol% to 30 vol%. . The preferred amount of nitrous oxide is a value obtained experimentally. Specifically, an amorphous carbon film containing about 15 atomic% of hydrogen is formed with a thickness of 3.5 nm, and the surface layer portion is suboxidized. Irradiated with ions formed using nitrogen and a mixed gas of nitrogen, the surface of the amorphous carbon film has a surface layer portion depth of 0.8 nm. It is calculated from the mixing ratio.

  In the step of ionizing the mixed gas of nitrous oxide and nitrogen and irradiating the surface of the carbon film containing hydrogen with ions, it is preferable to accelerate the ions and then irradiate the surface of the carbon film containing hydrogen. Specifically, for example, it is preferable to collide with the surface of the base material D while accelerating toward the base material D, which is set to a negative potential by the third power source 108.

  Further, for example, an RF (Radio Frequency) or VHF (Very High Frequency) AC power source is connected to the base material D, and the base material D is connected to the ground at a position facing the surface on which the carbon film containing hydrogen is formed. A device in which a flat plate is arranged can also be used. In this case, the mixed gas can be ionized by an electric field generated between the substrate D and the flat plate connected to the ground, and this gas can be accelerated to irradiate the surface of the substrate D.

  The place where the flat plate connected to the earth should just be arrange | positioned so as to oppose the film-forming surface of the base material D is not specifically limited. However, for example, when a carbon film is formed by the ion beam vapor deposition method and the mixed gas is ionized and irradiated by the apparatus, the flat plate connected to the ground is positioned farther from the substrate D than the anode electrode 105, In other words, in the case of FIG. 1, it is preferable that the anode electrode 105 is disposed on the left side in the drawing.

  As described above, by irradiating the surface of the carbon film containing hydrogen with the ions formed from the mixed gas, the surface of the carbon film can be dehydrogenated and nitrided, and the lubricant on the surface of the carbon film can be reduced. It is possible to increase wettability, increase hardness, and realize a high surface smoothness inherent to a carbon film containing hydrogen inherently.

  When performing the step of irradiating the surface of the carbon film containing hydrogen with ions formed from the mixed gas, for example, the substrate D is irradiated by applying a magnetic field from the outside of the film forming apparatus. It is preferable to increase the ion density of the nitrous oxide gas. Thus, it is preferable to increase the dehydrogenation effect on the surface of the carbon film containing hydrogen by increasing the ion density of the nitrous oxide gas irradiated toward the substrate D.

  In the carbon film manufacturing method of the present embodiment, the timing of introducing the mixed gas of nitrous oxide and nitrogen into the film forming chamber 101 is not particularly limited. For example, the deposition may be performed by mixing the carbon gas containing hydrogen and the raw material gas G containing hydrogen introduced into the deposition chamber 101 after or after the carbon film containing hydrogen.

  However, if nitrous oxide gas is supplied during the formation of a carbon film containing hydrogen, the film density of the carbon film may decrease. Therefore, after the carbon film containing hydrogen is formed, a mixed gas of nitrous oxide and nitrogen is used. It is preferable to introduce. In particular, it is more preferable that the gas G in the film formation chamber 101 is once exhausted to complete the formation of the carbon film containing hydrogen. As described above, after the gas G in the film formation chamber 101 is once exhausted to complete the formation of the carbon film containing hydrogen, the nitrous oxide gas or the like is introduced into the film formation chamber 101 so that the hydrogen is removed. The dehydrogenation and nitridation of the surface of the carbon film containing it can be performed more effectively.

  Note that in the case where nitrous oxide gas or the like is introduced before exhausting the raw material gas G containing carbon and hydrogen introduced into the film formation chamber 101, the introduction of the nitrous oxide gas and the film formation chamber 101 are performed. It is preferable to advance the exhaust in the interior simultaneously. By performing the operation in this manner, it is possible to increase the replacement speed with nitrous oxide gas or the like in the film formation chamber.

  In the present invention, the step of forming a carbon film containing hydrogen on the surface of the substrate and the step of ionizing a mixed gas of nitrous oxide and nitrogen and irradiating the surface of the carbon film containing hydrogen are separately performed. It is preferable to carry out with the apparatus of. This eliminates the need for replacement of the process gas in the apparatus as described above, thereby improving the efficiency of the carbon film manufacturing process and eliminating the adverse effects of the residence gas in the previous step.

  Further, in the apparatus for forming a carbon film containing hydrogen shown in FIG. 1, the carbon film containing hydrogen is formed only on one surface of the substrate D, but the present invention is not limited to such a structure. It is possible to form a carbon film containing hydrogen on both surfaces of the substrate D. In this case, for example, an apparatus similar to the case where a carbon film containing hydrogen is formed only on one surface of the substrate D is used. The configuration can be performed by arranging the both sides of the base material D in the film formation chamber 101.

  According to the carbon film manufacturing method of the present embodiment described above, a carbon film containing hydrogen with high wettability to the lubricant and high hardness can be obtained. Furthermore, a dense carbon film containing hydrogen with high surface smoothness can be obtained.

  When such a carbon film containing hydrogen is used as a protective film for a magnetic recording medium or the like, the thickness of the carbon film containing hydrogen can be reduced, so that the distance between the magnetic recording medium and the magnetic head is reduced. It can be set narrowly. As a result, it is possible to increase the recording density of the magnetic recording medium and increase the corrosion resistance of the magnetic recording medium.

[Second Embodiment]
A configuration example of the magnetic recording medium of this embodiment will be described.
The magnetic recording medium of this embodiment includes a substrate, a magnetic layer provided on at least one surface side of the substrate, and carbon containing hydrogen provided on the surface of the magnetic layer opposite to the surface facing the substrate. And a membrane. In the carbon film containing hydrogen, the hydrogen concentration on the surface opposite to the surface facing the magnetic layer is lower than the maximum hydrogen concentration in the film, and the carbon film containing hydrogen is at least the surface facing the magnetic layer. The surface on the opposite side is nitrided.
Hereinafter, the magnetic recording medium of the present embodiment will be specifically described.
An example of a cross-sectional configuration of the magnetic recording medium of the present embodiment is shown in FIG.

  The magnetic recording medium of the present embodiment can have a structure in which, for example, as shown in FIG. 2, a magnetic layer 210 and a carbon film (protective layer) 24 containing hydrogen are sequentially laminated on both surfaces of a substrate 20, A lubricating layer 25 can be formed on the outermost surface. Further, the magnetic layer 210 can be constituted by, for example, the soft magnetic layer 21, the intermediate layer 22, and the recording magnetic layer 23. Here, an example is shown in which each layer is formed on both surfaces of the substrate 20 as a center. However, the present invention is not limited to this mode, and for example, each layer can be formed only on one surface.

  In the carbon film 24 containing hydrogen, the hydrogen concentration on the surface 242 opposite to the surface 241 facing the magnetic layer 210 is lower than the maximum hydrogen concentration in the film. At least the surface 242 opposite to the surface 241 facing the magnetic layer is nitrided. In particular, it is preferable that the surface layer portion on the surface 242 side opposite to the surface 241 facing the magnetic layer 210 is nitrided in the carbon film containing hydrogen. The carbon film 24 containing hydrogen is preferably formed by, for example, the carbon film manufacturing method described in the first embodiment.

The film thickness of the carbon film 24 containing hydrogen is not particularly limited. However, since it is dense and dense, it can be made thinner than other protective films, for example, the carbon film 24 containing hydrogen. It is also possible to make the film thickness about 2 nm or less.
By adopting the above structure, the carbon film 24 containing hydrogen has high wettability with a lubricant, high flatness, high hardness, denseness, and uniform thickness.

Therefore, in the magnetic recording medium of the present embodiment, the distance between the magnetic recording medium and the magnetic head can be set narrow. As a result, the recording density of the magnetic recording medium is increased and the magnetic recording medium It is possible to improve the corrosion resistance.
Hereinafter, each layer other than the carbon film 24 containing hydrogen of the magnetic recording medium will be described.

  Although it does not specifically limit as the board | substrate 20, A nonmagnetic board | substrate can be used preferably. Specifically, for example, from Al-based substrates, Al-alloy substrates such as Al-Mg alloys, ordinary soda glass, aluminosilicate glass, crystallized glass, silicon, titanium, ceramics, and various resins Any substrate such as a substrate can be preferably used. Among these, it is more preferable to use an Al alloy substrate, a glass substrate such as crystallized glass, or a silicon substrate.

  Further, the average surface roughness (Ra) of the substrate surface is preferably 1 nm or less, more preferably 0.5 nm or less, and particularly preferably 0.1 nm or less.

  The configuration of the magnetic layer 210 is not particularly limited. For example, the magnetic layer 210 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. However, a perpendicular magnetic layer is preferable in order to realize a higher recording density.

The magnetic layer 210 is preferably formed from an alloy mainly composed of Co. For example, when the magnetic layer 210 is a magnetic layer for a perpendicular magnetic recording medium, first, a soft magnetic FeCo alloy (FeCoB, FeCoSiB, FeCoZr, FeCoZrB, FeCoZrBCu, etc.), FeTa alloy (FeTaN, FeTaC, etc.), Co alloy ( A soft magnetic layer 21 made of CoTaZr, CoZrNB, CoB, or the like can be disposed. The available and further laminated with an intermediate layer 22 made of Ru or the like, and a recording magnetic layer 23 made of 60Co-15Cr-15Pt alloy or 70Co-5Cr-15Pt-10SiO ₂ alloy.

  Further, an orientation control film (not shown) made of Pt, Pd, NiCr, NiFeCr, NiW or the like may be laminated between the soft magnetic layer 21 and the intermediate layer 22. On the other hand, as the magnetic layer 210 for the in-plane magnetic recording medium, a laminate of a nonmagnetic CrMo underlayer and a ferromagnetic CoCrPtTa magnetic layer can be used.

The thickness of the recording magnetic layer 23 is not particularly limited, but it is preferable that the thickness of the recording magnetic layer 23 be a certain value or more in order to obtain a certain value or more during reproduction. However, on the other hand, since various parameters representing the recording / reproducing characteristics are usually deteriorated as the output increases, it is preferable to set the film thickness to an optimum thickness in accordance with the configuration of the magnetic storage device to be installed. That is, the recording magnetic layer 23 is preferably formed so as to obtain sufficient head input / output according to the type of magnetic alloy used and the laminated structure.
The film thickness of the recording magnetic layer 23 is preferably, for example, 3 nm to 20 nm, and more preferably 5 nm to 15 nm.

As the lubricant used for the lubricating layer 25, a fluorinated liquid lubricant such as perfluoroether (PFPE) and a solid lubricant such as fatty acid can be preferably used. The thickness of the lubricating layer 25 is not particularly limited, but is preferably formed to a thickness of 1 nm to 4 nm, for example.
The method of applying the lubricant is not particularly limited, and can be performed by a known method such as a dipping method or a spin coating method.

  The manufacturing method of the magnetic recording medium according to the present embodiment is not particularly limited. For example, in-line film formation in which film formation processing is performed while sequentially transporting a substrate to be formed between a plurality of film formation chambers. The above layers can be formed using an apparatus (not shown) to manufacture a magnetic recording medium.

  In the magnetic recording medium of the present embodiment described above, the carbon film containing hydrogen has high wettability with the lubricant, high flatness, high hardness, denseness, and uniform thickness. .

  Therefore, in the magnetic recording medium of the present embodiment, the distance between the magnetic recording medium and the magnetic head can be set narrow. As a result, the recording density of the magnetic recording medium is increased and the magnetic recording medium It is possible to improve the corrosion resistance.

[Third Embodiment]
In the present embodiment, a configuration example of a magnetic storage device having the magnetic recording medium described in the second embodiment will be described.

  The configuration of the magnetic storage device of the present embodiment is not particularly limited as long as it has the magnetic recording medium described in the second embodiment. For example, the configuration shown in FIG. it can.

  In the magnetic storage device 30 shown in FIG. 3, information is recorded on the magnetic disk 31 that is the magnetic recording medium described in the second embodiment, a medium drive unit 32 that rotationally drives the magnetic disk 31, and the magnetic disk 31. The magnetic head 33 to be reproduced, the head driving unit 34, and the recording / reproducing signal processing system 35 can be provided.

  The recording / reproduction signal processing system 35 can process the input data and send the recording signal to the magnetic head 33, and can process the reproduction signal from the magnetic head 33 and output the data.

  In the magnetic storage device 30 in the present embodiment, the magnetic recording medium described in the second embodiment is used as the magnetic disk 31 to be configured. For this reason, the distance between the magnetic recording medium and the magnetic head can be set narrow, and it is possible to increase the recording density and the corrosion resistance.

  Specific examples will be described below, but the present invention is not limited to these examples.

Example 1
In this example, a magnetic recording medium having a cross-sectional shape shown in FIG. 2 was manufactured and evaluated.
First, the manufacturing procedure of the magnetic recording medium will be described.
An aluminum substrate on which NiP plating, which is a nonmagnetic substrate, was applied was prepared as the substrate 20.

Next, the magnetic layer 210 was formed on both surfaces of the substrate 20 mounted on the carrier using an in-line film forming apparatus (not shown). Specifically, the magnetic layer 210 is made of a soft magnetic layer 21 made of FeCoB having a thickness of 60 nm, an intermediate layer 22 made of Ru having a thickness of 10 nm, and a 70Co-5Cr-15Pt-10SiO ₂ alloy having a thickness of 15 nm. The recording magnetic layer 23 was formed by laminating sequentially.

Then, the base material D mounted on the carrier and having the magnetic layer formed on both surfaces of the substrate 20 is transferred to the film forming chamber 101 having the same apparatus configuration as the film forming apparatus shown in FIG. 1, and this magnetic layer is formed. A carbon film 24 containing hydrogen, that is, a protective film, was formed on both surfaces of the substrate D.
The structure of the film forming apparatus used in this embodiment will be described with reference to FIG.

  The film forming chamber 101 of the film forming apparatus had a cylindrical shape with an outer diameter of 180 mm and a length of 250 mm, and the material of the chamber wall 101a constituting the film forming chamber 101 was SUS304.

  In the film forming chamber 101, a coiled cathode electrode 104 made of tantalum having a length of about 30 mm and a cylindrical anode electrode 105 surrounding the cathode electrode are provided. The anode electrode 105 is made of SUS304, has an outer diameter of 140 mm, and a length of 40 mm. The distance between the cathode electrode 104 and the substrate D was 160 mm.

  Furthermore, a cylindrical magnet 109 surrounding the periphery of the chamber wall 101a was disposed so that the anode electrode 105 was positioned at the center thereof. The magnet 109 has an inner diameter of 185 mm and a length of 40 mm. Inside, 20 NdFe-based sintered bar magnets of 10 mm square and 40 mm length are arranged in parallel at equal intervals, and the S pole is the base material. Each sintered bar magnet was arranged so that the D side and the N pole were on the cathode electrode 104 side. The total magnetic force of the magnet 109 is 50 G (5 mT). During the formation of the carbon film containing hydrogen, the magnet 109 was rotated at 100 rpm.

In FIG. 1, a carbon film containing hydrogen is formed on one surface side of the substrate D, but the cathode electrode 104, the anode electrode 105, and the magnet 109 are also formed on the other surface side of the substrate D. Etc. are arranged in the same manner, and a film forming apparatus capable of simultaneously forming films on both surfaces of the substrate S is used.
And the process of forming the carbon film containing hydrogen on the surface of the base material D was performed on condition of the following.

  Gasified toluene was used as a source gas when forming a carbon film containing hydrogen. As film formation conditions, first, the gas flow rate of the source gas supplied to the film formation chamber 101 was 2.9 SCCM, and the reaction pressure was 0.2 Pa. Further, the cathode power was 225 W (AC 22.5 V, 10 A). Then, the voltage between the cathode electrode 104 and the anode electrode 105 is 75 V, the current is 1650 mA, the ion acceleration voltage is 200 V, 180 mA, the film formation time is 1.5 seconds, and hydrogen is added so that the thickness becomes 3.5 nm. The containing carbon film was formed.

  After the step of forming the carbon film containing hydrogen on the surface of the substrate, the supply of the source gas was stopped and the film formation chamber 101 was evacuated for 2 seconds. Next, a process of ionizing a mixed gas of nitrous oxide and nitrogen under the following conditions and irradiating the surface of the carbon film containing hydrogen with this ion was performed.

After the inside of the film formation chamber 101 was evacuated, nitrous oxide was supplied into the film formation chamber 101 at a gas flow rate of 0.1 SCCM, nitrogen at a gas flow rate of 2 SCCM, and a reaction pressure of 5 Pa. The amount of nitrous oxide gas contained in this mixed gas is 4.8% by volume. The cathode power was set to 128 W (AC16V, 8A). Further, the surface of the carbon film containing hydrogen was irradiated with ionization formed from a mixed gas with a voltage between the cathode electrode and the anode electrode of 75 V, a current of 1000 mA, an ion acceleration voltage of 200 V and 90 mA, and a treatment time of 1 second. . Thereby, dehydrogenation and nitridation of the surface of the carbon film containing hydrogen were performed.
Thereafter, a perfluoropolyether lubricant was applied to the surface of the carbon film containing hydrogen in a thickness of 1.4 nm.

(Comparative Example 1)
In Comparative Example 1, only the nitrous oxide gas was used for the nitrous oxide and nitrogen mixed gas of Example 1, and no nitrogen gas was used. That is, after the film formation chamber 101 was evacuated, nitrous oxide was supplied into the film formation chamber 101 at a gas flow rate of 2 SCCM and a reaction pressure of 5 Pa.

(Example 2)
In Example 2, with respect to the mixed gas of nitrous oxide and nitrogen of Example 1, the flow rate of nitrous oxide was 0.3 SCCM, the flow rate of nitrogen was 2 SCCM, and the reaction pressure was 5 Pa (the amount of nitrous oxide gas is 13% by volume).

Example 3
In Example 3, with respect to the mixed gas of nitrous oxide and nitrogen of Example 1, the flow rate of nitrous oxide was 0.05 SCCM, the flow rate of nitrogen was 2 SCCM, and the reaction pressure was 5 Pa (the amount of nitrous oxide gas was 2.4% by volume).
(Evaluation and results of magnetic recording media)

  The hydrogen concentration distribution measurement and the nitrogen concentration distribution measurement in each hydrogen-containing carbon film 24 of the magnetic recording media manufactured in Examples 1 to 3 and Comparative Example 1 were performed. Further, the magnetic recording media of Example 1 and Comparative Example 1 were evaluated by performing Raman spectroscopy measurement, scratch test, and corrosion test.

Regarding the measurement of the hydrogen concentration distribution and the nitrogen concentration distribution in the carbon film containing hydrogen, EPMA (Electron
The probe was analyzed using a Probe Micro Analyzer. The measurement results of the hydrogen concentration distribution are shown in Table 1, and the measurement results of the nitrogen concentration distribution are shown in Table 2, respectively.

For Raman spectroscopy, B / A was measured using a Raman spectrometer manufactured by JEOL. B / A here is a value calculated using the peak intensity of the Raman spectrum as the B value and the peak intensity when the baseline correction is performed as the A value. It shows that it is a hard carbon film, so that the value of this B / A is small, there are few polymer components in the carbon film containing hydrogen. The results are shown in Table 3.

The scratch test was performed using a SAF tester manufactured by Kubota Corporation. The test condition was that the magnetic recording medium was rotated at 12000 rpm, and the surface of the magnetic recording medium was repeated for 2 hours at a speed of 5 inches / second using a PP6 head. The presence or absence was confirmed.
For each of Example 1 and Comparative Example 1, such a scratch test was performed on 20 magnetic recording media, and the generation rate (%) was examined. The results are shown in Table 4.

For the corrosion test, after leaving the magnetic recording medium in an environment of 90 ° C. and 90% humidity for 96 hours, the number of corrosion spots (pieces / surface) generated on the surface of the magnetic recording medium is counted with an optical surface inspection machine. did. The detection accuracy was set to a diameter of 5 μm or more. The results are shown in Table 5.

  As shown in Tables 1 and 2, it can be confirmed that in the magnetic recording media of Examples 1 to 3, dehydrogenation and nitridation proceed in the surface layer portion of the carbon film 24 containing hydrogen as compared with Comparative Example 1. It was. The reason why the hydrogen concentration decreased in the surface layer portions of Examples 1 to 3 is considered that nitriding and dehydrogenation of the carbon film surface proceeded in a well-balanced manner.

  Further, since the magnetic recording medium of Example 1 is superior to the magnetic recording medium of Comparative Example 1 in the Raman spectroscopic measurement results shown in Table 3, it can be confirmed that the magnetic recording medium is a dense and smooth film. . Further, regarding the result of the scratch test shown in Table 4, the magnetic recording medium of Example 1 has a lower scratch generation rate than the magnetic recording medium of Comparative Example 1, and the carbon film 24 containing hydrogen has a high hardness. It can also be confirmed that it has excellent scratch resistance.

  As shown in Table 5, it was confirmed that the number of corrosion spots in the magnetic recording medium of Example 1 was smaller than that in Comparative Example 1. This means that the magnetic recording medium has excellent corrosion resistance. Since the surface layer portion of the carbon film 24 containing hydrogen is nitrided at a high concentration as described above, the wettability of the lubricant is increased. it is conceivable that.

G Source gas D Substrate 101 Deposition chamber 101a Chamber wall 102 Holder 103 Inlet tube 104 Cathode electrode 105 Anode electrode 106 First power source 107 Second power source 108 Third power source 109 Magnet 110 Exhaust tube 20 Substrate 210 Magnetic layer 24 Hydrogen Containing carbon film (protective layer)
241 Surface 242 facing the magnetic layer Opposite surface 30 Magnetic storage device 31 Magnetic disk 32 Medium drive unit 33 Magnetic head 34 Head drive unit 35 Recording / reproduction signal processing system

Claims (6)

Forming a carbon film containing hydrogen on the surface of the substrate; ionizing a mixed gas of nitrous oxide and nitrogen; and irradiating the surface of the carbon film containing hydrogen with ions formed by the ionization. The manufacturing method of the carbon film which has these. 2. The method for producing a carbon film according to claim 1, wherein the amount of nitrous oxide contained in the mixed gas is in the range of 1% by volume to 80% by volume. 3. The method for producing a carbon film according to claim 1, wherein in the step of irradiating the surface of the carbon film containing hydrogen with the ions, the ions are accelerated and then irradiated onto the surface of the carbon film containing hydrogen. Forming a carbon film containing hydrogen on the surface of the base material, introducing a source gas containing carbon and hydrogen into a deposition chamber, ionizing the source gas, accelerating the ions, The method for producing a carbon film according to any one of claims 1 to 3, further comprising a step of irradiating the surface of the substrate. A substrate, a magnetic layer provided on at least one surface of the substrate, and a carbon film containing hydrogen provided on a surface of the magnetic layer opposite to the surface facing the substrate. The hydrogen-containing carbon film has a hydrogen concentration on a surface opposite to the surface facing the magnetic layer lower than a maximum hydrogen concentration in the film, and the hydrogen-containing carbon film is at least the magnetic layer. A magnetic recording medium in which a surface opposite to a facing surface is nitrided. A magnetic storage device comprising the magnetic recording medium according to claim 5.

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