JP2005158092A - Magnetic recording medium, magnetic storage device, and manufacturing method for magnetic recording medium - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a magnetic recording medium realizing high density recording provided with a protective film excellent in corrosion resistance and durability and capable of being thinned, its magnetic storage device, and a manufacturing method for the magnetic recording medium. <P>SOLUTION: The magnetic recording medium 10 is provided with a substrate 11, a base layer 12, a non-magnetic intermediate layer 13, a magnetic layer 14 and the protective film 16 successively layered on the substrate 11, and a lubricating layer 18 formed on the protective film 16. A boundary mixing layer 15 at the boundary of the magnetic layer 14 and the protective film 16 is deposited in a self-forming manner when the protective film 16 is deposited. When the protective film is deposited, by setting substrate bias to be in the range of ≥0 V and <80 V by a negative voltage and setting an atmospheric gas pressure during film formation to be in the range of 5 Pa-10 Pa as needed further, the deposition of the boundary mixing layer 15 is suppressed or prevented. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a magnetic recording medium and a magnetic storage device capable of high-density recording, and more particularly to a magnetic recording medium in which the spacing between a magnetic head and a magnetic layer is reduced.

  In recent years, due to the rapid spread of the Internet and improvement in communication speed, the amount of data handled has increased dramatically, and magnetic storage devices with storage capacities on the order of 100 GB have been installed in personal computers and image recording devices. ing. The need for a storage device having a larger storage capacity is increased, and since it is used in a normal environment of a general household, higher durability than ever is required. In storage devices, it has become increasingly difficult to achieve both higher recording density and improved durability.

  In a storage device such as a hard disk drive, in order to improve recording density, it is necessary to reduce the distance between the recording layer of the magnetic recording medium and the recording / reproducing element of the magnetic head. The methods include thinning the protective film covering the recording layer of the magnetic recording medium and the recording / reproducing element of the magnetic head, and reducing the flying height of the magnetic head from the magnetic recording medium. However, if the protective film is simply thinned, the protective film is mechanically weakened and the corrosion resistance is lowered, and the long-term reliability of the magnetic recording medium becomes a problem.

Conventionally, a DLC film (diamond-like carbon film) formed by sputtering, which has high mechanical strength and is chemically inert, has been used for these protective films. However, in order to further reduce the thickness of the protective film, a CVD (chemical vapor deposition) method, an IBD (Ion Beam Deposition) method, or an FCA method (Filtered Cathodic Arc method) that can form a carbon film having a uniform and high quality film quality is available. It has come to be used. In these methods, even in the case of thin films, the search for film quality improvement toward high hardness and high density that maintains the same durability and corrosion resistance as in the past has been continued, and it has been a precursor of carbon films so far. By applying an appropriate substrate bias to ionized carbon or hydrocarbon and depositing on the substrate, the sp ³ property ratio of carbon-carbon bonds is increased, resulting in high hardness and high density. (For example, refer to Patent Document 1).

  Further, as the protective film becomes thinner, the role of the lubricating layer formed on the protective film has become more important. The lubricating layer generally has a skeleton of perfluoropolyether (PFPE), and a PFPE lubricant having a hydroxyl group or a phenyl group as a terminal group of the skeleton is mainly used. The lubricating layer has a role in which the end group is bonded to the protective film, and the PFPE skeleton relaxes the stress caused by the contact or sliding of the magnetic head, thereby preventing the magnetic characteristics of the recording layer from deteriorating and mechanical damage. ing.

When the protective film is a carbon film, if the wettability or adhesion of the PFPE lubricant is low, the lubricant may be scattered due to the centrifugal force of rotation of the magnetic disk due to long-term use, or the magnetic head and the magnetic recording medium Due to the phenomenon of scattering due to the air flow generated in the gap, the film thickness of the lubricating layer is reduced, and finally a so-called head crash occurs. On the other hand, methods for improving wettability and adhesion by surface treatment of various protective films have been proposed. Examples of the surface treatment include ultraviolet irradiation treatment (for example, see Patent Documents 2 and 3), oxygen-containing plasma treatment (for example, see Patent Document 4), and the like.
JP 2000-105916 A Japanese Patent Laid-Open No. 7-085461 JP-A-8-124142 JP-A-4-049522 IEEE Trans. Mag., Vol. 37, (2001) p1789-1791

  However, according to the study by the present inventor, the following problems have been clarified from the viewpoint of further thinning of the protective film aiming at higher recording density.

  FIG. 1 is an enlarged cross-sectional view showing an interface between a magnetic layer of a conventional magnetic recording medium and a carbon film of a protective layer. As shown in FIG. 1, in the conventional magnetic recording medium 100, when the carbon film 103 is formed on the magnetic layer 101 for recording information by a sputtering method or the like, if the substrate bias is set high in order to improve the hardness, An interface mixed layer 102 is formed at the interface between the magnetic layer 101 and the carbon film 103. The interfacial mixed layer 102 damages the outermost surface of the magnetic layer 101 when ionized carbon that is a precursor of the carbon film 103 collides with the substrate, and carbon or the like and the magnetic material are physically mixed, or It is chemically bonded.

  In the interface mixed layer 102, in terms of magnetic properties, the magnetic layer 101 is physically damaged, or a carbide or the like of the material constituting the magnetic layer 101 is formed. It has disappeared. Further, from the viewpoint of the function as a protective film, the interfacial mixed layer 102 is easily corroded because the carbon film 103 is mixed with the metal element of the magnetic layer 101, and the film quality is deteriorated. Therefore, in the magnetic recording medium 100, the thickness of the magnetic layer 101 and the carbon film 103 is reduced, and the electromagnetic conversion characteristics, durability, and corrosion resistance are deteriorated. Furthermore, when the film thickness of the carbon film 103 is increased in order to improve durability and corrosion resistance, there is a problem that the spacing between the magnetic head and the magnetic layer increases, and the electromagnetic conversion characteristics deteriorate.

  Further, by the ultraviolet irradiation treatment on the surface of the lubricating layer 104 after applying the lubricant, the bonding force between the lubricant molecules constituting the lubricating layer 104 and the carbon film 103 can be increased by controlling the ultraviolet irradiation time and the ultraviolet intensity. it can. However, since the active point density on the surface of the carbon film 103 gradually decreases from the atmospheric exposure after the film formation, the coverage of the lubricant changes depending on the atmospheric exposure time until the lubricant is applied. Variations in coverage occur. Further, there is a problem that the lubricant is distributed in islands due to the decrease in the active site density, and is fixed as it is by irradiation with ultraviolet rays, resulting in a decrease in the lubrication function.

  The oxygen-containing plasma treatment on the surface of the carbon film 103 is effective in improving the adhesion rate of the lubricant and increasing the bonding force. However, since the carbon film 103 is exposed to plasma and radicals, oxidation proceeds to the inner part of the carbon film 103 to cause a change in hardness, or the carbon film 103 is locally etched and disappears. As the thickness of the thin film 103 becomes smaller, it becomes a fatal problem. Furthermore, since the active sites on the surface of the carbon film 103 formed by the oxygen-containing plasma treatment decrease with time, it is preferably performed immediately before applying the lubricant. Therefore, it is necessary to introduce a new plasma processing apparatus, and it is inevitable that the facility is complicated and the number of processes is increased.

  In the FCA method, carbon ions, which are carbon film precursors, and neutral carbon particles (macroparticles) are evaporated and generated from a graphite cathode target by arc discharge. The neutral carbon particles are captured and removed by the filter unit before reaching the film formation chamber in which the magnetic recording medium 100 is disposed. However, a very small amount of carbon particles that could not be captured in the filter unit may be deposited on the magnetic layer 101, and the carbon particles cause a crash of a magnetic head having a low flying height. Although the filter part can be configured to have a multi-stage configuration to completely remove the carbon particles, there is a problem that the production efficiency is lowered because carbon ions are also captured and the loss increases accordingly.

  Therefore, the present invention has been made in view of the above problems, and the general purpose of the present invention is to provide a magnetic recording film that can be thinned, has a protective film excellent in corrosion resistance and durability, and can perform high-density recording. It is to provide a medium, a magnetic storage device thereof, and a method of manufacturing a magnetic recording medium.

  A specific first object of the present invention is to manufacture a magnetic recording medium capable of high-density recording with reduced spacing between the magnetic head and the magnetic layer and having long-term reliability, its magnetic storage device, and magnetic recording medium Is to provide a method. A specific second object of the present invention is to form a lubricating layer with excellent coverage and adhesion without damaging the thinned protective film, and with high reliability, high density recording is possible. And a method for manufacturing a magnetic recording medium. A specific third object of the present invention is to provide a method of manufacturing a magnetic recording medium that prevents the deposition of macro particles and reduces the thickness of the protective film.

  According to one aspect of the present invention, a magnetic recording includes a substrate, a magnetic layer provided above the substrate, a protective film provided on the magnetic layer, and a lubricating layer provided on the protective film. A protective film forming step of forming the protective film by a vacuum process film forming method using ions of the protective film material, wherein the substrate bias is set to 0 V or more at a negative voltage in the protective film forming step. A method for manufacturing a magnetic recording medium is provided, wherein the magnetic recording medium is set to a range of less than 80V.

  According to the present invention, when a protective film is formed using a vacuum process film forming method that ionizes a film forming material, for example, chemical vapor deposition method or FCA method, the substrate bias is 0 V or more and less than 80 V as a negative voltage. When the ions of the protective film material are deposited on the surface of the magnetic layer, the physical damage to the surface of the magnetic layer and the material constituting the magnetic layer and the protective film are chemically combined. The generation of the interfacial mixed layer can be suppressed or prevented. Therefore, the spacing between the magnetic head and the magnetic layer can be reduced, the S / N can be improved, and the recording density can be increased. In addition, since almost the entire thickness of the protective film on the surface of the magnetic layer has a good quality, even if the protective film is thinned, it has excellent durability and corrosion resistance and excellent long-term reliability.

  According to another aspect of the present invention, a magnetic recording medium comprising a substrate, a recording layer formed above the substrate, and a protective film formed on the recording layer, the recording layer comprising: Provided is a magnetic recording medium characterized in that the average film thickness of an interface mixed layer formed by mixing the recording layer and the material constituting the protective film is 0.5 nm or less at the interface with the protective film. The

According to the present invention, compared to the conventional magnetic recording medium in which a protective film is formed by applying a substrate bias of several hundreds V (absolute value), the protective film having a low kinetic energy is formed when the protective film is formed. By depositing material ions on the surface of the magnetic layer, the formation of an interfacial mixed layer formed by physically or chemically mixing ions of the magnetic layer and the protective film material is suppressed or prevented. Reduce the thickness to 0.5 nm or less. Therefore, the spacing between the magnetic head and the magnetic layer can be reduced, the S / N can be improved, and the recording density can be increased. Here, 0.5 nm is a film thickness of a monoatomic layer to a diatomic layer as a carbon film, for example, and when the surface density of a magnetic recording medium, for example, an in-plane recording medium is 60 Gb / inch ² or more, the magnetic head-magnetic layer It is also an allowable film thickness in terms of spacing. Of course, the smaller the average film thickness of the interfacial mixed layer, the better.

  According to another aspect of the present invention, there is provided a magnetic recording medium comprising a substrate, a recording layer formed above the substrate, and a carbon protective film formed on the recording layer, wherein the carbon protection The film is composed of a first protective film formed on the magnetic layer side and a second protective film formed on the first protective film. The first protective film is formed by the second protective film. There is also provided a magnetic recording medium characterized in that the ratio of the amount of hydrogen atoms to the amount of carbon atoms is high.

  According to the present invention, the second protective film provided on the surface side of the magnetic recording medium is harder and more durable because the ratio of the hydrogen atomic weight to the carbon atomic weight is low. On the other hand, the first protective film formed on the magnetic layer side is relatively soft because the ratio of the amount of hydrogen atoms to the amount of carbon atoms is higher than that of the second protective film. The first protective film is formed by, for example, a chemical vapor deposition method with a low substrate bias (a negative voltage is used to reduce the absolute value) or set to 0 V, and the second protective film is a substrate. It is formed in the same manner by increasing the bias (increasing the absolute value with a negative voltage). When the initial protective film is formed, the substrate bias is reduced, and when the hard protective film is formed, the initial protective film protects the surface of the magnetic layer, thereby suppressing the formation of an interface mixed layer on the magnetic layer surface. Or it is prevented.

  According to another aspect of the present invention, there is provided a magnetic storage device including any one of the above magnetic recording media and recording / reproducing means.

  According to the present invention, by suppressing / preventing the formation of the interface mixed layer, the spacing between the magnetic head and the magnetic layer is reduced, the S / N is improved, and a protective film having excellent durability and corrosion resistance is provided. Therefore, the recording density can be increased and long-term reliability can be obtained.

  According to the present invention, the S / N is improved by suppressing or preventing the formation of an interface mixed layer between the magnetic layer and the protective film, and it has excellent durability and corrosion resistance, and has a high density recording. And a magnetic recording medium having long-term reliability can be realized.

  Embodiments according to the present invention will be specifically described with reference to the drawings as necessary.

(First embodiment)
FIG. 2 is a sectional view of the magnetic recording medium according to the first embodiment of the present invention. Referring to FIG. 2, in the magnetic recording medium 10, a substrate 11, a base layer 12, a nonmagnetic intermediate layer 13, a magnetic layer 14, and a protective film 16 are sequentially laminated on the substrate 11, and further, the lubricating film 16 is lubricated. The layer 18 is formed. The interface mixed layer 15 at the interface between the magnetic layer 14 and the protective film 16 is formed in a self-forming manner when the protective film 16 is formed.

  The interface mixed layer 15 includes physical damage given to the magnetic layer 14 when the material constituting the protective film 16 is deposited on the magnetic layer 14, and the material constituting the magnetic layer 14 and the material constituting the protective film 16. Since it is formed by chemically bonding, the magnetic properties are deteriorated or the ferromagnetism is almost lost. The interfacial mixed layer 15 is preferably as thin as possible or not formed in order to increase the spacing between the magnetic head and the magnetic layer 14.

  In the present invention, the protective film 16 is formed by a CVD method such as a plasma CVD method, an ALCVD (Atomic Layer CVD) method, and an FCA method among film forming methods using a vacuum process for forming the protective film 16. . When the protective film 16 is formed, in order to prevent the interfacial mixed layer 15 formed on the surface of the magnetic layer 14 from being thinned or not formed, a precursor that becomes the protective film 16, for example, the protective film 16 is a carbon film. The kinetic energy when the carbon ions are deposited on the surface of the magnetic layer 14 is reduced, or the kinetic energy when the gas ions of the deposition atmosphere gas collide with the surface of the magnetic layer 14 is reduced. Methods for reducing the kinetic energy of precursors and gas ions include (1) lowering the substrate bias, (2) increasing the atmospheric gas pressure, and (3) utilizing the adsorption phenomenon of the protective film material. Can be mentioned. In particular, it is preferable to reduce the kinetic energy of precursors and gas ions when the protective film 16 is formed on the surface of the magnetic layer 14 to have a monoatomic layer or a diatomic layer, that is, a film thickness of about 0.5 nm.

  The substrate bias is set to a negative voltage in the range of 0 V to less than 80 V (preferably, a negative voltage of 0 V to 30 V, particularly preferably 0 V). Since the degree of acceleration of the precursor and gas ions due to the substrate bias is reduced, kinetic energy can be reduced. Moreover, it is preferable to set atmospheric gas pressure to 1 Pa-50 Pa (especially 10-20 Pa) in CVD methods, such as a plasma CVD method. Precursors and gas ions collide with atmospheric gas molecules to reduce kinetic energy. Hereinafter, a specific method for forming the protective film 16 will be described.

[Protective film formation method by plasma CVD method]
A method for forming the protective film 16 using the plasma CVD method, which constitutes the method for manufacturing the magnetic recording medium of the present embodiment, will be described below.

First, the substrate 11 formed up to the magnetic layer 14 by the method described later is disposed in a plasma CVD apparatus and evacuated to 10 ⁻⁶ Pa or less. The substrate temperature is set in the range of 0 ° C. to 300 ° C., for example, and a process gas is introduced. When forming a carbon film as the protective film 16, CH ₄ , C ₂ H ₄ , C ₂ H ₆ , and C ₆ H ₅ CH ₃ are used as the process gas, and H ₂ is used as the carrier gas, for example.

  Further, it is preferable to introduce an inert gas such as Ar gas in order to increase the pressure in the film forming chamber, and to set the total pressure in the film forming chamber to a range of 1 Pa to 50 Pa (preferably 10 Pa to 20 Pa). . The kinetic energy of the process gas ions is reduced by increasing the probability that the ions of the process gas ionized by the plasma collide with the Ar atoms to reduce the mean free path. The inert gas may be He, Ne, Kr, or Xe in addition to Ar. From the viewpoint of lowering the plasma electron temperature and increasing the ionization rate of process gas ions, it is preferable to mix an inert gas having a large atomic weight such as Kr or Xe with Ar gas. Further, in terms of damage caused by inert gas ions to the surface of the magnetic layer 14 due to the substrate bias, light elements are preferable, and for example, He and Ne are preferable.

  The substrate bias is set to a negative voltage of 0 V to less than 80 V (preferably a negative voltage of 0 V to 30 V, particularly preferably 0 V). By reducing the substrate bias, the ions of the process gas and the atmospheric gas are accelerated and the increase in speed is suppressed. The discharge power is set to 1000 W, for example, and the film is formed until the initial thickness of the carbon film is at least 0.5 nm. The surface of the magnetic layer 14 can be protected by setting the initial layer thickness to 0.5 nm or more. Note that the entire thickness of the carbon film may be formed under the conditions for forming the initial layer 16A-1.

  Next, the discharge is stopped, the atmospheric gas pressure is set to a range of 0.1 Pa to 5 Pa, and is lower than the atmospheric gas pressure when the initial layer is formed. The atmospheric gas pressure may be controlled by the flow rate of Ar gas and the introduction of Ar gas may be stopped. The flow rate of the process gas may be controlled as necessary. Further, the substrate bias is increased from −80 V to −1000 V, and the absolute value is made larger than the substrate bias when the initial layer is formed. Since the surface of the magnetic layer 14 is covered with the initial layer, the interface mixed layer 15 is not formed even if the substrate bias is increased, and the process gas ions are accelerated and have sufficient kinetic energy, so that it can be hardened. it can. When the atmospheric gas pressure and the substrate bias are stabilized, discharge is started and a hard layer is formed to a desired film thickness.

As described above, as in the magnetic recording medium 20 shown in FIG. 3, the carbon film 16A formed by this method includes the initial layer 16A-1 and the hard layer 16A-2, and the initial layer 16A-1 has low kinetic energy. Since it is formed by the ions of the process gas, damage to the surface of the magnetic layer 14 is suppressed, and the formation of the interface mixed layer 15 is substantially prevented. Since the initial layer 16A-1 is deposited with a low kinetic energy state bonding of carbon atoms, relative to that in many hard layer 16A-2 in the sp ³ bonds, contains many sp ² bond . In addition, since the ions of the process gas constituting the hard layer 16A-2 are deposited with high kinetic energy at the interface between the initial layer 16A-1 and the hard layer 16A-2, it is assumed that the sp3 bond is dominant. Is done.

  In addition, since the initial layer 16A-1 has a substrate bias whose absolute value is smaller than that of the hard layer 16A-2, the kinetic energy of the incident carbon ions and the precursor of the protective film is low. The ratio of hydrogen atomic weight to atomic weight is high. The ratio of the hydrogen atom weight to the carbon atom weight can be measured by using, for example, Rutherford Backscattering Spectroscopy and Hydrogen Forward Scattering Spectroscopy.

  In addition, it is preferable to use an apparatus in which the position of the plasma formation region and the substrate are separated from each other as the plasma CVD apparatus. It is possible to prevent the plasma from contacting the surface of the magnetic layer 14 and grinding the surface.

[Protective film formation method by ALCVD method]
A method for forming the protective film 16 using the ALCVD method, which constitutes the method for manufacturing the magnetic recording medium of the present embodiment, will be described below.

The ALCVD method is a method in which a monoatomic layer made of a material gas is adsorbed on a surface on which a film is formed to cause an oxidation reaction to form an oxide layer for each monoatomic layer. Since the oxide layer is formed by chemical adsorption and thermal oxidation of the material gas, it is possible to prevent the interface mixed layer 15 from being formed on the surface of the magnetic layer 14 shown in FIG. In the ALCVD method, for example, by using Al (CH ₃ ) ₃ , ZrCl ₄ , and TiI ₄ as raw materials and using H ₂ O, H ₂ O ₂ , and O ₂ as oxidizing gases, respectively, an Al ₂ O ₃ film, A ZrO ₂ film or a TiO ₂ film can be formed.

First, the substrate formed up to the magnetic layer 14 is disposed in an ALCVD apparatus and evacuated to 10 ⁻⁶ Pa or less. The substrate temperature is set in the range of 70 ° C. to 500 ° C., for example. When an Al ₂ O ₃ film is formed as the protective film 16, Al (CH ₃ ) ₃ is used and H ₂ O is used as the oxidizing gas.

Next, for example, a gas of trimethylaluminum Al (CH ₃ ) ₃ having a pressure of 100 Pa to 1000 Pa is introduced into the ALCVD apparatus to adsorb a monoatomic layer on the surface of the magnetic layer 14 (about 3 seconds), and immediately Al (CH _{3). 3} ) is exhausted sufficiently, and then, for example, H ₂ O at a pressure of 100 Pa to 1000 Pa is introduced. The CH ₃ group is replaced with an OH group, and an Al ₂ O ₃ film is formed. Next, H ₂ O is exhausted, and the procedure from the introduction of the material gas to the exhaust of H ₂ O is repeated to form an Al ₂ O ₃ film having a desired film thickness.

  In the ALCVD method, since the precursor of the protective film is adsorbed on the surface of the magnetic layer 14, no physical damage occurs on the surface of the magnetic layer 14. Therefore, the interfacial mixed layer 15 is not formed at the interface between the magnetic layer 14 and the protective film 16, and the spacing between the magnetic head and the magnetic layer can be reduced.

[Protective film formation method by FCA method]
A method for forming the protective film 16 using the FCA method, which constitutes the method for manufacturing the magnetic recording medium of the present embodiment, will be described below.

  The FCA apparatus forms an arc discharge between the cathode target made of graphite and the anode in the discharge section, so that carbon ions and carbon atoms are agglomerated from the cathode target heated to 10,000 ° C. or more by the arc discharge. The carbon particles and the like are evaporated and generated, and the carbon particles are captured by the 45 ° vent type filter portion so that only the carbon ions reach the substrate surface.

When the protective film 16 is formed using the FCA method, it is formed as follows. First, the substrate formed up to the magnetic layer 14 is disposed in the FCA apparatus and evacuated to 10 ⁻⁵ Pa or less. The substrate temperature is set in the range of 0 ° C. to 300 ° C., for example. In terms of suppressing the formation of the interfacial mixed layer 15, an inert gas such as Ar gas is introduced, and the pressure is preferably 10 ⁻² Pa to 10 ⁻¹ Pa. The kinetic energy of carbon ions when reaching the substrate can be reduced.

  The kinetic energy of carbon ions is dominated by kinetic energy and substrate bias when evaporating from the cathode target by arc discharge. It is preferable to set the direct-current power applied between the cathode target and the anode to 1 kW to 4 kW. The substrate bias is set to a negative voltage in the range of 0 V to less than 80 V (preferably a negative voltage of 0 V to 30 V, particularly preferably 0 V). The kinetic energy of carbon ions when reaching the substrate can be reduced.

  Next, after the discharge is started and the discharge is stabilized, film formation on the substrate is started. For example, the film thickness of the carbon film deposited is controlled by the film formation time.

  In the FCA method, the formation of the interface mixed layer 15 can be suppressed or prevented by controlling the substrate bias and further the high frequency power supply power.

  Hereinafter, the configuration other than the protective film 16 of the magnetic recording medium 10 according to the present embodiment will be described.

  Referring to FIG. 2 (or FIG. 3), the substrate 11 can be a glass substrate, a NiP plated aluminum alloy substrate, a silicon substrate, a ceramic substrate, or the like. A NiP layer or the like may be formed on a glass substrate, a silicon substrate, a ceramic substrate, or the like by a sputtering method or the like.

  As the underlayer 12, a Cr layer grown in the (002) plane direction with a thickness of 40 nm is formed by setting the substrate temperature to 200 ° C. by sputtering or vapor deposition. Specifically, the underlayer 12 has a thickness of 10 nm to 100 nm and is not limited to a Cr layer. For example, a Cr alloy layer such as CrW, CrMo, CrTi or the like is used instead of the Cr layer. By adding W or the like to Cr, the lattice constant is controlled to achieve lattice matching with the nonmagnetic intermediate layer 13 formed on the underlayer 12, thereby making the epitaxial growth of the nonmagnetic intermediate layer 13 more complete. Can do. The thickness of the underlayer 12 is preferably 2 nm or more and 50 nm or less. If it is thicker than 50 nm, the crystal grains of the underlayer 12 grow, the in-plane size (for example, the diameter) of the crystal grains becomes excessive, and is successively taken over by each layer growing on the underlayer 12. The crystal grains of the recording layer 16 become excessively large, increasing the medium noise. On the other hand, if the thickness is smaller than 2 nm, the crystallinity of the nonmagnetic intermediate layer 13 is lowered.

  The nonmagnetic intermediate layer 13 is formed by a sputtering method or a vapor deposition method. For example, a CoCr alloy or a CoCrTa alloy having a substrate temperature of 180 ° C. and grown in the (11-20) plane direction with a thickness of 20 nm is used. Specifically, the nonmagnetic intermediate layer 13 is made of a CoCr alloy having a thickness of 1 nm to 10 nm (Cr content is 25 atomic% or more), or an alloy obtained by adding Ta, Pt, W or the like to a CoCr alloy. The nonmagnetic intermediate layer 13 functions as a buffer layer that alleviates lattice mismatch between the underlayer 12 and the stabilization layer 14 (and the recording layer 16), and has the (11-20) plane as the growth direction, and the stabilization layer. 14 (and recording layer 16) has the function of improving the in-plane orientation of the c-axis of the CoCrPt alloy.

  The recording layer 16 has a nonmagnetic coupling layer 15 between these layers, the c-axis is oriented in the in-plane direction (for example, grows in the (11-20) plane direction), and is antiferromagnetically coupled to each other, that is, stable. It has a laminated ferrimagnetic structure in which the magnetizations of the conversion layer 14 and the recording layer 16 are antiparallel. Each of the stabilization layer 14 and the recording layer 16 is a ferromagnetic layer. For example, ferromagnetic layers having the same composition and different thicknesses are formed. Specifically, the stabilization layer 14 and the recording layer 16 are made of CoCrPt (Cr: 10 atom% to 25 atom%, Pt: 3 atom% to 15 atom%), CoCrPtB (B: 2 atom% to 10 atom%). , CoCrPtTa, CoCrPtTaNb, or other CoCrPt as a main component, and a composition in which fourth and fifth elements are added thereto. Among these, CoCrPtB can increase the coercive force with a small Pt content as compared with, for example, CoCrPtTa, and thus is preferable from the viewpoint of high recording density and low cost. CoCrPtB is also suitable from the viewpoint of crystal grain refinement. A fifth element may be further added to CoCrPtB.

  The magnetic layer 14 may have a laminated ferri structure. The laminated ferrimagnetic structure has a structure in which a first ferromagnetic layer, a nonmagnetic coupling layer such as a Ru film having a thickness of 0.6 nm to 0.9 nm, and a second ferromagnetic layer are laminated.

Further, the magnetic recording medium 10 according to the present embodiment may be a perpendicular magnetic recording medium. Even in the perpendicular magnetic recording medium, it is important to reduce the spacing in order to increase the recording density. The perpendicular magnetic recording medium has a soft magnetic backing between a substrate 11 and an underlayer 12 shown in FIG. Further, the magnetic layer 14 is a perpendicular magnetization film having an easy magnetization axis in the film thickness direction. By selecting the composition of the nonmagnetic intermediate layer 13 as appropriate, the easy axis of magnetization of the magnetic layer 14 can be oriented in the film thickness direction. For example, a Ru film, RuCo film, CoCr film or the like is used for the nonmagnetic intermediate layer 13. Further, the perpendicular magnetization film may be a granular film having a columnar structure of (CoCrPt)-(SiO ₂ ). The granular film is suitable for high density recording because of low medium noise.

  The lubricating layer 19 is formed on the protective film 16 with a thickness of 0.5 nm to 3 nm, and is formed by a dipping method or a spin coating method. Specifically, the lubricant is diluted with chlorofluorocarbon solvents (for example, Fluorinert (trade name, manufactured by 3M)) such as ZDOL, Z25, AM3001 (namely, trade name, manufactured by Augmont) with perfluoropolyether as the main chain. Then, an immersion method, for example, a pulling method for controlling the film thickness of the lubricating layer by the speed at which the substrate is lifted can be used. Of course, the liquid level of the fluorocarbon solvent containing the lubricant may be lowered at a predetermined speed to control the film thickness of the lubricating layer.

  Before the lubricating layer 19 is applied, the surface of the protective film 16 may be modified with ozone water to modify the surface. The adhesion and covering properties of the lubricant can be improved, and the thin protective film 16 can be prevented / suppressed from being damaged by sliding with the magnetic head.

  As the ozone water, for example, ozone water generated by a silent discharge type ozone generator is dissolved in pure water. The ozone concentration of the ozone water is preferably set in the range of 0.3 ppm to 50 ppm. If it is lower than 0.3 ppm, the processing time is long, and if it exceeds 50 ppm, the rate at which the carbon film is oxidized and consumed increases, making it difficult to control the processing time. Moreover, it is preferable that the temperature of ozone water is 0 degreeC-25 degreeC from the point of controllability of ozone concentration. The ozone generation method is not limited, and other methods may be used.

  In the ozone water treatment, for example, when the magnetic recording medium is a magnetic disk, the ozone water is sprayed onto the rotating magnetic disk surface using a spin cleaning machine. Ozone water to which ultrasonic waves having a frequency of several tens of kHz to several MHz may be used, and the ozone water is filled with ultrasonic waves having a frequency of several tens of kHz to several MHz, preferably high frequency (700 kHz to 3 MHz). A magnetic recording medium may be immersed in an ultrasonic cleaner. By adding ultrasonic waves, the effect of removing organic deposits and surface oxidation of ozone water can be enhanced.

  After the ozone water treatment, the surface of the protective film 16 is washed with pure water to remove the remaining ozone water, and then dried. Further, it is preferable to apply the lubricant promptly after drying, specifically within 1 hour, preferably within 20 minutes. If it exceeds 1 hour, an effect will reduce remarkably.

  Organic substances, metal fine particles, metal ions, and the like adsorbed on the surface of the protective film 16 can be removed by the ozone water treatment, and the surface of the protective film 16 is oxidized to form an adsorption point for the lubricant molecules. it can. As a result, the adhesion and covering properties of the lubricant can be improved.

[Example 1]
On the aluminum alloy substrate, a NiP film (25 nm) / AlRu film (25 nm) / CrW film (4.5 nm) / CoCrPtB film (thickness 15 nm) were formed from the substrate side using a DC magnetron sputtering apparatus.

Next, using a plasma CVD apparatus, C ₂ H ₄ gas (flow rate: 100 sccm) and hydrogen gas (flow rate: 10 sccm) are used as source gases, and Ar gas is further introduced to adjust the atmospheric gas pressure (total pressure). A carbon film having a thickness of 0.5 nm was formed while maintaining 10 Pa, with a plasma output of 1000 W, a substrate bias of 0 V, and a substrate temperature of 200 ° C.

  Next, the substrate bias is set to −500 V, the introduction of Ar gas is stopped, the atmospheric gas pressure (total pressure) is set to 3 Pa, and the other conditions are the same as those described above. Formed. The plasma discharge was stopped while the substrate bias and the atmospheric gas pressure were changed.

  Next, a lubricating layer having a thickness of 1.0 nm was formed on the carbon film by a pulling method (immersion time 30 seconds) using a 0.2 vol% AM3001 solution.

  The cross section of the magnetic disk thus produced was photographed with a FETEM (high resolution transmission electron microscope) and the photograph was observed. As a result, no interfacial mixed layer was observed at the interface between the CoCrPtB film and the carbon film. That is, the average film thickness of the interface mixed layer was 0.0 nm, and the average maximum film thickness was 0.9 nm.

The average film thickness was obtained by sampling four points every 90 degrees in the radial center of the magnetic disk and taking a cross-sectional TEM image (500,000 times). As shown in the explanatory diagram of FIG. On the photographic paper, the total magnification is 8 million times, and the film thicknesses X _{1 to} X ₁₀ of the ₁₀ interfacial mixed layers are measured at approximately equal intervals in the in-plane direction. Thickness.

The average maximum thickness is the distance Y ₁ of the distance between the connecting peak portions of the surface of the lower surface of the connecting valleys linear LN1 and interfacial mixing layer of the interfacial mixing layer linear LN2 average film thickness as well as 10 the to Y ₁₀ was measured and the average maximum thickness by averaging the thickness of the total 40 points. The average maximum film thickness corresponds to a value obtained by adding the size of irregularities having a period in the in-plane direction of the magnetic layer surface in the range of nanometers to several tens of nanometers in addition to the above average film thickness. Such minute irregularities are formed when ionized carbon or atmospheric gas ions collide with the substrate, and the recording density is improved, that is, the in-plane size of the recording layer constituting one recording unit is very small. The effect on the S / N increases as the ratio increases. The average maximum film thickness is preferably 1.0 nm or less, and particularly preferably 0.0 nm.

  In addition, a C1s spectrum was measured using an X-ray photoelectron spectrometer (XPS, manufactured by VG Scientific, model ESXALAB220iXL) using a spot diameter of 1000 μm, a detection angle of 12 degrees, and an Al · Kα ray as an X-ray source.

  FIG. 5 is a diagram showing the XPS C1s spectrum of Example 1, and FIG. 6 is a diagram showing the peak area ratio of Example 1 (the results of Comparative Example 1 described later are also shown). Referring to FIG. 5, a peak of carbide (Co—C bond) (binding energy: 283.5 eV) is hardly recognized, and the area ratio obtained by the analysis software attached to XPS is as shown in FIG. It was 1% of the total carbon peak area. Moreover, the film thickness of the interface mixed layer calculated | required on the assumption of the carbide model from this result was 0.5 nm or less.

Next, a corrosion resistance test was performed. In the corrosion resistance test, 1 cm ³ of dilute nitric acid was dropped on the substrate surface, recovered after 1 hour, and the Co elution amount measured by an inductively coupled plasma mass spectrometer (ICP-MS) was 1.2 μg / m ² .

[Comparative Example 1]
The magnetic disk of Comparative Example 1 was formed in the same manner as in Example 1 except for the carbon film formation conditions. A carbon film having a thickness of 2.0 nm was formed in the same manner as in Example 1 except that Ar gas was not introduced, the atmospheric gas pressure (total pressure) was maintained at 3 Pa, and the substrate bias was −500 V. Formed.

  When the cross section of the magnetic disk thus prepared was photographed and observed by FETEM in the same manner as in Example 1, the average film thickness of the interface mixed layer at the interface between the CoCrPtB film and the carbon film was 0.8 nm, and the average maximum film The thickness was 1.8 nm.

FIG. 7 is a diagram showing the C1s spectrum of Comparative Example 1. 6 and FIG. 7, the area ratio of the carbide peak of the C1s spectrum of Comparative Example 1 is 10% of the area of the total carbon peak, and the film thickness of the interface mixed layer obtained by assuming the carbide model is Depending on the carbide model, it was in the range of 0.7 nm to 1.7 nm. Further, the Co elution amount by the corrosion resistance test was 2.8 μg / m ² .

  According to Example 1 and Comparative Example 1, since the average film thickness of the interface mixed layer of Comparative Example 1 is 0.8 nm, the average film thickness of the interface mixed layer of Example 1 is 0.0 nm. It can be seen that the interfacial mixed layer of Example 1 is greatly reduced. This also shows that the interface mixed layer of Example 1 is significantly reduced in the average maximum film thickness.

  Also, the analysis of the C1s spectrum by XPS shows that since the area ratio of the carbide peak of Comparative Example 1 is 10%, Example 1 is 1%. It can be seen that the interfacial mixed layer of Example 1 is greatly reduced.

Further, for the corrosion resistance test, the Co elution amount of Comparative Example 1 is 2.8 μg / m ² , whereas Example 1 is 1.2 μg / m ² , so that the corrosion resistance of the carbon film of Example 1 is It can be seen that the properties are excellent.

  As described above, the carbon film of Example 1 in which the initial layer of the carbon film was formed by using the plasma CVD method with the substrate bias set to 0 V, and the hard layer was formed with the substrate bias set to −500 V, the substrate bias set to −500 V. It can be seen that the average film thickness and the average maximum film thickness of the interfacial mixed layer were reduced and the spacing was reduced with respect to the formed carbon film of Comparative Example 1. It can also be seen that Example 1 is superior in terms of corrosion resistance.

[Example 2]
On the glass substrate, a CrTi film (25 nm) / AlRu film (25 nm) / CrW film (4.5 nm) / CoCrPtB film (thickness 15 nm) were formed from the substrate side using a DC magnetron sputtering apparatus.

Next, a carbon film having a thickness of 5.0 nm is formed on the CoCrPtB film using an FCA (Filtered Cathodic Arc) apparatus with a degree of vacuum of 10 ⁻³ Pa, an arc current of 100 A, an arc voltage of 25 V, and a substrate bias of 0 V. did. Next, a lubricating layer was formed in the same manner as in Example 1.

  When the cross section of the magnetic disk thus prepared was photographed and observed by FETEM in the same manner as in Example 1, the average film thickness of the interface mixed layer at the interface between the CoCrPtB film and the carbon film was 0.0 nm, and the average maximum film The thickness was 1.0 nm, and the thickness from the CoCrPtB film surface to the carbon film surface was 5.0 nm.

  The S / N at 300 kFCI using a composite magnetic head was 15 dB. The composite magnetic head had a GMR reproducing head, the flying height was 13 nm, and the peripheral speed was 15 m / s.

  In the durability test, the scratch condition of the carbon film was observed by visual judgment at a load of 40 g, a test radius of 23 mm, and a rotation speed of 500 rpm on the magnetic head, and no scratch was recognized up to 4000 turns.

[Comparative Example 2]
The magnetic disk of Comparative Example 2 was formed in the same manner as in Example 2 except for the carbon film forming conditions. As the carbon film, a carbon film having a thickness of 5.0 nm was formed on the CoCrPtB film in the same manner as in Example 2 except that the substrate bias was set to −250 V using an FCA apparatus. Next, a lubricating layer was formed in the same manner as in Example 2.

  When the cross section of the magnetic disk thus produced was photographed and observed by FETEM in the same manner as in Example 2, the average film thickness of the interface mixed layer at the interface between the CoCrPtB film and the carbon film was 1.2 nm, and the average maximum film The thickness was 2.5 nm and the thickness from the CoCrPtB film surface to the carbon film surface was 6.2 nm.

The S / N was measured in the same manner as in Example 2 and was 13 dB. The durability test was measured in the same manner as in Example 2, and no scratch was observed until 4000 turns.

According to Example 2 and Comparative Example 2, the average film thickness of the interface mixed layer of Example 2 is 0.0 nm, whereas the average film thickness of the interface mixed layer of Comparative Example 2 is 1.2 nm. It can be seen that the spacing of 2 is reduced. This also shows that the interface mixed layer of Example 2 is significantly reduced in the average maximum film thickness.

  Correspondingly, it can be seen that the S / N of Comparative Example 2 is 13 dB, whereas the S / N of Example 2 is 15 dB, which is 2 dB higher. On the other hand, it can be seen that the durability test is similar in Example 2 and Comparative Example 2.

  Therefore, by forming the carbon film by reducing the absolute value of the substrate bias by the FCA method, it was possible to reduce the spacing while maintaining the durability and to improve the S / N ratio.

[Example 3]
In the same manner as in Example 2, a CoCrPtB film was formed on a glass substrate.

Next, an alumina film having a thickness of 7.2 nm was formed on the CoCrPtB film by the ALCVD method. Specifically, a substrate on which a CoCrPtB film is formed is placed in a deposition chamber, the substrate is evacuated to 5 × 10 ⁻⁵ Pa, and the substrate is heated to 75 ° C. Next, trimethylaluminum (Ar gas is used as a carrier gas in the deposition chamber) Al (CH ₃ ) ₃ ) gas was introduced (pressure 5 × 10 ⁻² Pa), left for 1 second to form a trimethylaluminum film and then evacuated, and then water vapor was introduced using Ar gas as a carrier gas (pressure 5 × 10 ⁻² Pa) Leave for 1 second and convert the trimethylaluminum film to an alumina film and exhaust. These were repeated until the thickness was 7.2 nm. Next, a lubricating layer was formed in the same manner as in Example 1.

  When the cross section of the magnetic disk thus prepared was photographed and observed by FETEM in the same manner as in Example 1, the average film thickness of the interface mixed layer at the interface between the CoCrPtB film and the alumina film was 0.0 nm, and the average maximum film The thickness was 1.0 nm, and 7.2 nm from the CoCrPtB film surface to the alumina film surface.

  The S / N was measured in the same manner as in Example 2 and was 12 dB. The durability test was performed in the same manner as in Example 2, and no scratch was observed until 1800 laps.

[Comparative Example 3]
The magnetic disk of Comparative Example 3 was formed in the same manner as in Example 3 except for the conditions for forming the alumina film. The alumina film is formed using an RF sputtering apparatus, an alumina target, an Ar gas atmosphere (0.5 Pa), a substrate bias set to −200 V, a discharge power of 500 W, and no substrate heating. A 6 nm alumina film was formed. Next, a lubricating layer was formed in the same manner as in Example 2.

  When the cross section of the magnetic disk thus prepared was photographed and observed by FETEM in the same manner as in Example 3, the average film thickness of the interface mixed layer at the interface between the CoCrPtB film and the alumina film was 1.2 nm, and the average maximum film The thickness was 2.4 nm, and the surface from the CoCrPtB film surface to the alumina film surface was 8.8 nm.

  Further, S / N was measured in the same manner as in Example 2 and was 8.5 dB. The durability test was measured in the same manner as in Example 3, and no scratch was observed until 1800 laps.

  According to Example 3 and Comparative Example 3, the average film thickness of the interface mixed layer of Example 3 is 0.0 nm, while the average film thickness of the interface mixed layer of Comparative Example 3 is 1.2 nm. It can be seen that the spacing of 3 is reduced. This also shows that the interface mixed layer of Example 3 is greatly reduced in the average maximum film thickness as well.

  Correspondingly, it can be seen that the S / N of Comparative Example 3 is 8.5 dB, whereas the S / N of Example 3 is 12 dB and 3.5 dB higher. On the other hand, it can be seen that the durability test is similar between Example 3 and Comparative Example 3.

  Therefore, the material is chemically adsorbed by the ALCVD method and oxidized, thereby avoiding the formation of the interface mixed layer and forming the alumina film, thereby maintaining durability compared to the alumina film produced by the sputtering method. However, the spacing was reduced and the S / N ratio was improved.

[Example 4]
The magnetic recording medium according to this example is formed up to the protective film in the same manner as in Example 1, and then using a spin cleaning machine, the inside of the spin cleaning machine is replaced with a nitrogen gas atmosphere, and ozone water containing 32 ppm of ozone is added. Sprayed and washed for 30 seconds. Next, spin drying was performed at 4000 rpm for 20 seconds, and z-tetraol was applied on the protective film with a thickness of 1 nm using a solution obtained by diluting z-tetraol to about 0.2 wt% of Vertrel XF (Mitsui DuPont Fluorochemical). Next, the lubricating layer was heat-treated (130 ° C., 1 hour).

  The contact angle of the magnetic disk thus produced with pure water was measured according to JIS K6800 and the lubricant coverage was evaluated. The contact angle was 103 degrees.

  In addition, the magnetic disk according to the present embodiment is cleaned by immersing it in the bartrel XF, and the ratio (residual ratio) of the film thickness after cleaning to the film thickness before cleaning of the lubricating layer is measured to evaluate the adsorption force to the protective film. did. The residual rate was 90% or more. The durability test was performed in the same manner as in Example 2, and no scratch was observed on the protective film until 8500 laps.

[Comparative Example 4]
A magnetic disk according to Comparative Example 4 was produced in the same manner as in Example 4 except that pure water was used instead of ozone water. The contact angle, the residual ratio of the lubricating layer, and the durability test were performed in the same manner as in Example 4. The contact angle was 81 degrees, the residual rate was 45%, and in the durability test, the protective film was scratched after 4000 turns.

  According to Example 4 and Comparative Example 4, since the contact angle of Comparative Example 4 is 81 degrees and the coverage of Example 4 is 103 degrees, Example 4 has a higher coverage than Comparative Example 4. I understand that. Further, since the remaining ratio is 45% in Comparative Example 4 and 90% or more in Example 4, it can be seen that Example 4 has a higher bonding force between the lubricant molecules and the protective film.

In relation to these, in Comparative Example 4, scratches occurred in the protective film after 4000 turns in the durability test, whereas in Example 4, scratches were not recognized up to 8,500 times. It can be seen that the durability is greatly improved.
(Second Embodiment)
A magnetic recording medium according to a second embodiment of the present invention provided with a protective film formed using the FCA method will be described. Since the basic configuration other than the protective film of the magnetic recording medium is the same as that of the magnetic recording medium shown in the first embodiment and FIG.

  FIG. 8 is a cross-sectional view schematically showing an FCA film forming apparatus used in the method for manufacturing a magnetic recording medium according to the present embodiment. Referring to FIG. 8, the FCA film forming apparatus 40 used in the present embodiment is roughly composed of a discharge part 41, a filter part 42, a deflecting part 43, and a film forming chamber 44.

  The discharge unit 41 includes a cathode target 45, an anode 46, a cathode coil 48, a striker 49, and the like. The cathode target 45 is made of graphite, and when a striker 49 strikes the surface of the cathode target 45 to which a DC voltage is applied, arc discharge is started between the cathode target 45 and the anode 46, and 10,000 ° C. is caused by the arc discharge. From the cathode target 45 heated as described above, carbon ions, carbon atoms, carbon particles in which carbon atoms are agglomerated, electrons, and the like are evaporated and generated. The cathode coil 48 has a function of increasing the ionization rate of carbon atoms evaporated from the cathode target 45 by applying a magnetic field parallel to the discharge axis of arc discharge. In this way, a carbon particle group composed of carbon ions, carbon atoms, carbon particles, and electrons is formed, and the beam shape is formed by the kinetic energy at the time of evaporation and the Coulomb force resulting from the potential difference in the FCA film forming apparatus 40. And supplied to the filter unit 42. In addition, since the cathode target 45, the anode 46, etc. become high temperature by arc discharge, it is cooled by supplying cooling water from the outside.

  The filter unit 42 uses a 45 ° vent type filter having two filter coils 50A and 50B. By applying a magnetic field perpendicular to the flow direction of the carbon particle groups (perpendicular to the paper surface of the drawing) by the filter coils 50A and 50B, the flow of charged particles in the carbon particle groups is deflected, and the other particles Trapping is performed on the inner wall of the FCA film forming apparatus 40 or the fin 52 provided on the inner wall. The principle of the filter is the Lorentz force acting on the charged particles moving in the magnetic field, and R = mv / (qB), where R is the radius of curvature when bending, where the charge in the carbon particle group These are the momentum mv and charge q of the particles, and the magnetic field B applied by the filter coil. Accordingly, by selecting v and B appropriately, only carbon ions can be selected, and carbon neutral atoms, particles, electrons, and the like are trapped.

  The filter unit 42 is provided with a pair or two pairs of raster magnets 51. With the raster magnet 51, the flow of carbon ions can be swung up and down or left and right, and a carbon film having a uniform film thickness can be formed.

  The film forming chamber 44 is provided with a substrate holding table 60 for holding the substrate 11 and is grounded via a DC power source. The substrate bias of the substrate 11 can be set by the power supply voltage of the DC power supply. The substrate 11 is held substantially perpendicular to the direction in which the carbon ion flux flows, and the substrate center is disposed at a distance L1 from the center axis CI of the carbon ion bundle when the substrate bias is 0V. Yes. The distance L1 is preferably larger than the sum of the size of the substrate 11, for example, when the substrate 11 is disk-shaped, the substrate radius RD and the radius RI of the carbon ion flux, that is, L1> RD + RI. The radius of the carbon ion bundle can be obtained from the film forming range by actually forming a film on the substrate. In such a substrate arrangement, a negative substrate bias is applied using the substrate bias application power source 61 to deflect the carbon ion flux toward the substrate 11 side.

  FIG. 9 is a diagram showing how the carbon ion flux is deflected when a predetermined substrate bias is applied. Referring to FIG. 9, carbon ions of positive ions are guided to the substrate 11 side by the Coulomb force (attracting force) because the substrate holding table 60 is applied with a negative voltage in the film forming chamber 44. Deposited on 11 magnetic layers. Since the neutral carbon particles go straight and reach a portion other than the substrate 11, it is possible to prevent the neutral carbon particles from being deposited on the substrate 11.

  FIG. 10 is a characteristic diagram showing the relationship between the carbon film and the substrate bias. Referring to FIG. 10, when the substrate bias is applied, the hardness increases and shows the maximum, and when the substrate bias is further increased to the negative side, the hardness gradually decreases. It is possible to form a carbon film having sufficient hardness even when the substrate bias is around −150V. When the substrate bias is increased to a negative side from −150 V, the number of carbon ions reaching the substrate 11 is decreased, and the film formation rate is significantly decreased. Therefore, by applying a substrate bias, it is possible to prevent neutral carbon particles from being deposited on the substrate 11 and at the same time to improve the hardness of the carbon film.

  Returning to FIG. 8, the carbon ion flux may be deflected to the substrate 11 side by using the deflecting unit 43 provided between the filter unit 42 and the film forming chamber 44. The deflection unit 43 is provided with a DC power supply 59 for applying a DC voltage to the parallel plate electrodes 58A and 58B and the parallel plate electrodes 58A and 58B. For example, by setting the electrode 58A to a predetermined negative voltage with respect to the electrode 58B, the carbon ion flux can be deflected toward the substrate 11 and neutral carbon particles can be prevented from reaching the substrate 11. The deflection unit 43 may be provided or may not be provided. Moreover, you may use with a substrate bias.

  In order to ensure the uniformity of the thickness of the carbon film, the substrate may be rotated at the time of film formation by a rotation drive unit 62 connected to the substrate holder as shown in FIG. Further, the substrate may be tilted with respect to the carbon ion bundle. Further, since it is continuously formed in a vacuum with a magnetic layer as a base, the substrate 11 or the substrate 11 is held between the film forming chamber for forming the recording layer and the like and the film forming chamber 44 for forming the carbon film. The substrate holding table 60 may be transported.

Nitrogen gas may be added to the atmospheric Ar gas in the FCA film forming apparatus 40. Nitrogen gas is ionized and taken into the carbon film 16, and the carbon film 16 doped with nitrogen can be formed. Doping with nitrogen can improve wettability and adhesion to the lubricant. The addition amount of nitrogen gas is set such that Ar gas flow rate: nitrogen gas flow rate is 90:10 to 0: 100. The pressure is preferably 1 × 10 ⁻³ Pa to 1 × 10 ⁻² Pa.

  FIG. 11 is a cross-sectional view schematically showing an FCA film forming apparatus equipped with an ion gun. In the figure, portions corresponding to the portions described above are denoted by the same reference numerals, and description thereof is omitted.

Referring to FIG. 11, the FCA film forming apparatus 70 is provided with an ion gun 72 in a film forming chamber 71,
The substrate holder 60 is provided to be inclined toward the ion gun 72. By irradiating the surface of the substrate 11 with nitrogen ions using the ion gun 72, nitrogen is taken into the carbon film and wettability and adhesion to the lubricant as in the film formation in the atmosphere to which the nitrogen gas is added. Can be improved. Similar to the FCA film forming apparatus shown in FIG. 8, the relationship between the distance L1 between the central axis of the carbon ion bundle and the center of the substrate, the substrate radius RD, and the radius RI of the carbon ion bundle is L1> RD + RI. preferable.

  In the present embodiment, the protective film 16 shown in FIG. 2 is formed as described above. When the FCA film forming apparatuses 40 and 70 are used, a carbon film is formed only on one side of the substrate 11. Therefore, when the magnetic recording medium 10 is a double-sided type, an FCA film forming apparatus is provided for each side. Alternatively, it may be formed by one FCA film forming apparatus by turning the substrate surface upside down. The thickness of the carbon film 16 is set to 0.5 nm to 5 nm, and is preferably 0.5 nm to 3 nm from the viewpoint of reducing the spacing between the magnetic head and the magnetic recording medium.

  According to the present embodiment, it is possible to prevent neutral carbon particles from being mixed into the carbon film and to form a thin carbon film with high hardness. As a result, a magnetic recording medium with high long-term reliability can be realized.

(Third embodiment)
A third embodiment of the magnetic storage device of the present invention will be described with reference to FIGS. FIG. 12 is a cross-sectional view showing a main part of a magnetic memory device according to the third embodiment of the present invention. FIG. 13 is a plan view showing the main part of the magnetic memory device shown in FIG.

  Referring to FIGS. 12 and 13, the magnetic storage device 80 generally includes a housing 83. In the housing 83, a motor 84, a hub 85, a plurality of magnetic recording media 86, a plurality of recording / reproducing heads 87, a plurality of suspensions 88, a plurality of arms 89, and an actuator unit 81 are provided. The magnetic recording medium 86 is attached to a hub 85 that is rotated by a motor 84. The recording / reproducing head 87 is an MR element (magnetoresistive element), GMR element (giant magnetoresistive element), TMR element (tunnel magnetic effect type), or CPP element (current perpendicular to plane element) reproducing head. It is composed of a composite head of 87A and a thin film head recording head 87B. Each recording / reproducing head 87 is attached to the tip of a corresponding arm 89 via a suspension 88. The arm 89 is driven by the actuator unit 81. The basic configuration itself of this magnetic storage device is well known, and detailed description thereof is omitted in this specification.

  The magnetic storage device 80 according to the present embodiment is characterized by a magnetic recording medium 86. The magnetic recording medium 86 is, for example, the magnetic recording medium according to the first embodiment and the second embodiment shown in FIGS. The number of magnetic recording media 86 is not limited to three, and may be one, two, or four or more.

  The basic configuration of the magnetic storage device 80 is not limited to that shown in FIGS. The magnetic recording medium 86 used in the present invention is not limited to a magnetic disk.

  According to the present embodiment, the magnetic storage device 80 has high writing performance of the magnetic recording medium 86, excellent thermal stability of the written bits, and low medium noise characteristics. High recording density can be achieved.

  Although the preferred embodiments of the present invention have been described in detail above, the present invention is not limited to the specific embodiments, and various modifications and changes can be made within the scope of the present invention described in the claims. Is possible.

  For example, in the third embodiment, the hard disk device is described as an example of the magnetic storage device, but the present invention is not limited to the hard disk device. For example, the present invention can be applied to a magnetic tape used in a magnetic tape device such as a helical scan video tape device or a computer magnetic tape device in which a large number of tracks are formed in the width direction of the magnetic tape. .

In addition, the following additional notes are disclosed regarding the above description.
(Supplementary Note 1) A method of manufacturing a magnetic recording medium having a substrate, a magnetic layer provided above the substrate, a protective film provided on the magnetic layer, and a lubricating layer provided on the protective film. There,
A protective film forming step of forming the protective film by a vacuum process film forming method using ions of the protective film material,
A method of manufacturing a magnetic recording medium, wherein the substrate bias is set in a range of 0 V or more and less than 80 V as a negative voltage in the protective film forming step.
(Additional remark 2) The said protective film formation process WHEREIN: The atmospheric gas pressure during film-forming is set to the range of 1 Pa-50 Pa, The manufacturing method of the magnetic recording medium of Additional remark 1 characterized by the above-mentioned.
(Additional remark 3) The said vacuum process film-forming method is either a chemical vapor deposition method and FCA method, The manufacturing method of the magnetic recording medium of Additional remark 1 or 2 characterized by the above-mentioned.
(Supplementary Note 4) In the protective film forming step,
Forming a first protective film having a thickness of 0.5 nm or more by setting the first substrate bias value;
Next, a second substrate bias value is set to further form a second protective film on the first protective film,
4. The method of manufacturing a magnetic recording medium according to claim 1, wherein the first substrate bias value is smaller in absolute value than the second substrate bias value. 5.
(Supplementary note 5) The method for manufacturing a magnetic recording medium according to supplementary note 4, wherein the first substrate bias value is set in a range of 0 V or more and less than 80 V as a negative voltage.
(Additional remark 6) The atmosphere gas pressure at the time of forming the said 1st protective film is set higher than the atmospheric gas at the time of forming the said 2nd protective film, The magnetic of Additional remark 4 or 5 characterized by the above-mentioned A method for manufacturing a recording medium.
(Additional remark 7) The atmosphere gas at the time of forming the first protective film and the second protective film includes a process gas including a protective film material and an inert gas. The method for manufacturing a magnetic recording medium according to appendix 6, wherein the atmospheric gas pressure when forming the first protective film by controlling the pressure is increased.
(Supplementary Note 8) The chemical vapor deposition method is an atomic layer deposition chemical vapor deposition method,
The method for manufacturing a magnetic recording medium according to appendix 3, wherein the protective film is any one of a group of aluminum oxide, zirconium oxide, and titanium oxide.
(Supplementary note 9) The method for manufacturing a magnetic recording medium according to supplementary note 3, wherein the protective film is formed by setting the substrate bias value in a range of 0 V or more and 30 V or less as a negative voltage using the FCA method.
(Supplementary Note 10) In a method for manufacturing a magnetic recording medium having a substrate, a magnetic layer provided above the substrate, a protective film provided on the magnetic layer, and a lubricating layer provided on the protective film. There,
A surface modification step of treating the surface of the protective film with ozone water;
A method of manufacturing a magnetic recording medium, further comprising a lubricating layer forming step of forming a lubricating layer by applying a lubricant.
(Supplementary Note 11) After the protective film formation step, a surface modification step of treating the surface of the protective film with ozone water;
The method for manufacturing a magnetic recording medium according to any one of appendices 1 to 10, further comprising a lubricating layer forming step of forming a lubricating layer by applying a lubricant.
(Additional remark 12) The said ozone water process sets the density | concentration of ozone water in the range of 0.3 ppm-50 ppm, The manufacturing method of the magnetic recording medium of Additional remark 10 or 11 characterized by the above-mentioned.
(Supplementary note 13) The magnetic treatment according to one of Supplementary notes 10 to 12, wherein the ozone water treatment is performed by spraying ozone water onto a protective film surface or immersing a magnetic recording medium in ozone water. A method for manufacturing a recording medium.
(Supplementary note 14) The method for manufacturing a magnetic recording medium according to supplementary note 13, wherein the ozone water treatment is performed while applying an ultrasonic wave.
(Supplementary note 15) A magnetic recording medium comprising a substrate, a recording layer formed above the substrate, and a protective film formed on the recording layer,
Magnetic recording, wherein an average film thickness of an interface mixed layer formed by mixing materials constituting the recording layer and the protective film is 0.5 nm or less at the interface between the recording layer and the protective film Medium.
(Supplementary Note 16) A magnetic recording medium comprising a substrate, a recording layer formed above the substrate, and a carbon protective film formed on the recording layer,
The carbon protective film comprises a first protective film formed on the magnetic layer side and a second protective film formed on the first protective film,
The magnetic recording medium according to claim 1, wherein the first protective film has a higher ratio of hydrogen atomic weight to carbon atomic weight than the second protective film.
(Supplementary note 17) A magnetic recording medium comprising a substrate, a recording layer formed above the substrate, and a protective film formed on the recording layer,
A magnetic layer having an average maximum film thickness of 1.0 nm or less of an interface mixed layer formed by mixing materials constituting the recording layer and the protective film at the interface between the recording layer and the protective film. recoding media.
(Supplementary note 18) A magnetic storage device comprising the magnetic recording medium according to any one of supplementary notes 15 to 17 and a recording / reproducing means.
(Additional remark 19) The generation | occurrence | production part which produces | generates a carbon particle group, the filter part which selects a carbon ion from a carbon particle group, and forms a carbon ion bundle, injects a carbon ion bundle, and forms a carbon film on this board | substrate A method for manufacturing a magnetic recording medium, comprising:
A substrate is placed on a substrate holding table and spaced apart from the position where the carbon ion bundle is irradiated when no substrate bias is applied,
A method of manufacturing a magnetic recording medium, comprising applying a substrate bias at a predetermined voltage to attract the carbon ion flux to the substrate surface to form a carbon film.
(Additional remark 20) The said predetermined voltage is set to the range of -10V--150V, The manufacturing method of the magnetic recording medium of Additional remark 19 characterized by the above-mentioned.
(Supplementary note 21) The method of manufacturing a magnetic recording medium according to supplementary note 19 or 20, wherein the substrate is rotated when the carbon film is formed.
(Appendix 22) Of the appendices 19-21, the atmosphere during the formation of the carbon film is that Ar gas is added with any one of a group of nitrogen gas, hydrogen gas, and CF ₄ gas. A method for producing a magnetic recording medium according to claim 1.
(Supplementary note 23) The method for manufacturing a magnetic recording medium according to any one of supplementary notes 19 to 22, wherein the substrate is irradiated with CF ₄ ions or hydrogen ions using an ion gun when the carbon film is formed.

It is sectional drawing which expands and shows the interface of the magnetic layer of the conventional magnetic recording medium, and the carbon film of a protective layer. 1 is a cross-sectional view of a magnetic recording medium according to a first embodiment of the invention. It is sectional drawing of the magnetic-recording medium which concerns on the modification of 1st Embodiment. It is explanatory drawing for calculating | requiring the average film thickness and average maximum film thickness of an interface mixed layer. It is a figure which shows the C1s spectrum of Example 1. It is a figure which shows the peak area ratio of Example 1 and Comparative Example 1. It is a figure which shows the C1s spectrum of the comparative example 1. It is sectional drawing which shows typically the FCA film-forming apparatus used for the manufacturing method of the magnetic-recording medium based on the 2nd Embodiment of this invention. It is a figure which shows the mode of the deflection | deviation of the carbon ion bundle at the time of applying a predetermined substrate bias. It is a characteristic view which shows the relationship between a carbon film and a substrate bias. It is sectional drawing which shows the other FCA film-forming apparatus typically. It is sectional drawing which shows the principal part of the magnetic memory device based on the 3rd Embodiment of this invention. It is a top view which shows the principal part of the magnetic memory device shown in FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10, 20 Magnetic recording medium 11 Substrate 14 Magnetic layer 15 Interface mixed layer 16 Protective film 16A Carbon film 18 Lubricating layer 40, 70 FCA film forming apparatus

Claims (10)

A method for producing a magnetic recording medium comprising a substrate, a magnetic layer provided above the substrate, a protective film provided on the magnetic layer, and a lubricating layer provided on the protective film,
A protective film forming step of forming the protective film by a vacuum process film forming method using ions of the protective film material,
A method of manufacturing a magnetic recording medium, wherein the substrate bias is set in a range of 0 V or more and less than 80 V as a negative voltage in the protective film forming step.   2. The method of manufacturing a magnetic recording medium according to claim 1, wherein in the protective film forming step, an atmospheric gas pressure during film formation is set in a range of 1 Pa to 50 Pa.   3. The method of manufacturing a magnetic recording medium according to claim 1, wherein the vacuum process film forming method is one of a chemical vapor deposition method and an FCA method. In the protective film forming step,
Forming a first protective film having a thickness of 0.5 nm or more by setting the first substrate bias value;
Next, a second substrate bias value is set to further form a second protective film on the first protective film,
4. The method of manufacturing a magnetic recording medium according to claim 1, wherein the first substrate bias value is smaller in absolute value than the second substrate bias value. 5. The chemical vapor deposition method is an atomic layer deposition chemical vapor deposition method,
4. The method of manufacturing a magnetic recording medium according to claim 3, wherein the protective film is any one selected from the group consisting of aluminum oxide, zirconium oxide, and titanium oxide. After the protective film forming step, a surface modification step of treating the surface of the protective film with ozone water;
4. The method of manufacturing a magnetic recording medium according to claim 1, further comprising a lubricating layer forming step of forming a lubricating layer by applying a lubricant.   7. The method of manufacturing a magnetic recording medium according to claim 6, wherein in the ozone water treatment, the concentration of ozone water is set in a range of 0.3 ppm to 50 ppm. A magnetic recording medium comprising a substrate, a recording layer formed above the substrate, and a protective film formed on the recording layer,
Magnetic recording, wherein an average film thickness of an interface mixed layer formed by mixing materials constituting the recording layer and the protective film is 0.5 nm or less at the interface between the recording layer and the protective film Medium. A magnetic recording medium comprising a substrate, a recording layer formed above the substrate, and a carbon protective film formed on the recording layer,
The carbon protective film comprises a first protective film formed on the magnetic layer side and a second protective film formed on the first protective film,
The magnetic recording medium according to claim 1, wherein the first protective film has a higher ratio of hydrogen atomic weight to carbon atomic weight than the second protective film. 10. A magnetic storage device comprising the magnetic recording medium according to claim 8 and recording and reproducing means.

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