JP4185112B2 - Lubricating film forming method, and magnetic recording medium or magnetic head slider manufacturing method using the same - Google Patents

Description

  The present invention relates to a lubricating film forming method and a method of manufacturing a magnetic recording medium or a magnetic head slider using the lubricating film forming method.

  It is necessary to form a lubricant film on the surface of a base material that comes into contact with other members such as the surface of a hard disk or the surface of a head slider in a hard disk drive, or has a possibility of such contact.

For example, as disclosed in Patent Documents 1 to 4, a method of heating the lubricant after applying the lubricant to the surface of the base material and fixing the lubricant to the surface of the base material, or Patent Document 5 In addition, a method of irradiating UV after applying a lubricant to the surface of a substrate, a method of irradiating neutral radicals after applying a lubricant to the surface of a substrate, as disclosed in Patent Document 6, and Patent Document As disclosed in 7-9, as disclosed in Patent Documents 10-14, a method of modifying the surface of the lubricant with plasma or gas during or after the formation of the lubricant on the surface of the substrate. A method of applying a lubricant having a polar group to the surface of a substrate, and applying a lubricant as described in Patent Document 15 and then irradiating a laser of 300 nm or less to blow off a part of the lubricant to form a thin film A method for forming a lubricating film such as a method is known.
JP-A-11-203670 JP 2001-93141 A JP 2000-322734 A JP 2003-228810 A JP 11-35452 A JP-A-6-215367 Japanese Patent Laid-Open No. 7-326151 JP 2004-152462 A JP 2002-109718 A Japanese Patent Laid-Open No. 6-44558 JP-A-5-143975 Japanese Patent Laid-Open No. 5-189975 JP-A-5-205246 JP-A-6-172479 JP 11-66555 A

  However, in the conventional method, the lubricant is not sufficiently fixed to the base material, and the durability of the lubricating film is not sufficient.

  The present invention has been made in view of the above problems, and provides a method for forming a lubricating film capable of exhibiting sufficient durability, and a method for manufacturing a magnetic recording medium or a magnetic head slider using the same. With the goal.

  The method for forming a lubricating film according to the present invention includes a step of irradiating a lubricant having an OH group applied to the surface of a substrate with an infrared laser beam that excites vibrations of OH bonds of OH groups.

  According to the present invention, the vibration of the OH bond of the OH group of the lubricant is excited by irradiation with infrared laser light. Therefore, the reactivity between the OH group of the lubricant and the surface of the substrate is increased, and it becomes easy to chemically bond the lubricant to the surface of the substrate, and the durability of the lubricant is increased.

  Specifically, the following mechanism can be considered. That is, there are terminal bonds called dangling bonds on the surface of the substrate. Usually, this dangling bond includes a state where it is not bonded to other atoms, a state where it is bonded to an OH group, a state where it is hydrogen bonded (adsorbed) to water molecules, and the like. According to the above invention, the vibration of the OH group of the lubricant is excited by the irradiation of the laser beam, the OH group is activated and the reactivity is increased, and the dangling bond on the substrate surface is bonded. It becomes easy. Therefore, the lubricant can be easily covalently bonded to the dangling bond on the surface of the base material through, for example, O atoms derived from OH groups. Therefore, the durability of the lubricating film is increased.

  Here, in the above step, it is preferable to irradiate infrared laser light having a wavelength of 0.9 to 8 μm, or to absorb energy corresponding to light having a wavelength of 0.9 to 8 μm by multiphoton absorption by the infrared laser. . In particular, an infrared laser beam having a wavelength of 0.9 to 1.1 μm or a wavelength of 2.7 to 3.0 μm is irradiated, or a wavelength of 0.9 to 1.1 μm by multiphoton absorption by the infrared laser, or It is preferable to absorb energy corresponding to light having a wavelength of 2.7 to 3.0 μm.

  Also, in the above step, multiphoton absorption is performed, and infrared laser light is irradiated so that a focal point of the infrared laser light is formed on the surface of the base material or a portion of the lubricant on the base material side. It is preferable to do.

  According to this, the OH group of the lubricant in the vicinity of the surface of the base material can be selectively excited by absorption of infrared light, so that it is possible to suppress unnecessary side reactions other than at the interface. Further, multiphoton absorption can be sufficiently performed even if the film formed by the lubricant is thick because light is hardly absorbed except at the focal point.

  Moreover, it is also preferable to use the infrared laser beam which permeate | transmitted the homogenizer as said infrared laser beam. In this case, since the intensity distribution of the laser light is flat in the plane by the homogenizer, a wide area can be quickly processed with a uniform irradiation intensity.

  The lubricant is preferably a layer having a thickness of 2 nm or less.

  According to this, since the infrared laser beam can reach the vicinity of the interface between the lubricant and the base material sufficiently, the absorption of the infrared laser light to the OH group of the lubricant located near the surface of the base material is prevented. It can be done efficiently.

The irradiation intensity of the infrared laser light is preferably 60 J / cm ² or less.

If the irradiation intensity exceeds 60 J / cm ² , the surface of the lubricant or the substrate may be damaged.

Specifically, for example, an infrared pulse laser beam is irradiated as an infrared laser beam, the irradiation intensity of the laser beam is 60 J / cm ² or less, the pulse width is 0.1 to 1 ms, the number of pulses is 1 to 10, and the pulse The frequency is preferably 10 to 50 Hz.

  Moreover, it is preferable to maintain the surface temperature of the substrate at 200 ° C. or lower during infrared laser irradiation.

  When the surface temperature of the substrate exceeds 200 ° C., the lubricant may evaporate or deteriorate, or the substrate may deteriorate.

  The lubricant is preferably a fluorinated organic compound having an OH group. In particular, a fluorinated organic compound having an OH group at the terminal is preferable.

  Fluorinated organic compound-based lubricants have high lubrication performance, but have been difficult to fix to conventional substrates. However, in the present invention, such a lubricant can be sufficiently fixed to the base material, so that a lubricating film excellent in lubricating performance and durability can be easily formed.

  Moreover, it is preferable that the surface of a base material is formed with the carbon material. In particular, the carbon material has sufficient performance as a surface protective film, but it is difficult to fix the lubricant because it is a chemically stable substance. However, according to the present invention, the lubricant can be sufficiently fixed to the surface of the base material formed of the carbon material.

  The method for producing a magnetic recording medium according to the present invention is the above-described method for forming a lubricating film on a lubricant applied to the surface of a magnetic recording medium.

  The method of manufacturing a magnetic head slider according to the present invention performs the above-described lubricating film forming method on the lubricant applied to the surface of the magnetic head slider.

  According to the present invention, there are provided a method for forming a lubricating film capable of exhibiting sufficient durability, and a method for manufacturing a magnetic recording medium or a magnetic head slider using the same.

  Preferred embodiments of the present invention will be described below with reference to the drawings. In the description of the drawings, the same elements are denoted by the same reference numerals, and redundant descriptions are omitted. In the drawings, the dimensional ratio does not necessarily match that described.

(Base material preparation process)
First, as shown in FIG. 1, a base material 10 to be processed is prepared. The material of the base material 10 is not particularly limited. For example, metals such as aluminum, aluminum alloys, titanium, metal oxides such as alumina, ceramics such as Altic (Al ₂ O ₃ -TiC), silicon, glass, inorganic materials such as carbon materials (amorphous carbon), polyethylene Examples include polymer compounds such as terephthalate, polyimide, polyamide, polycarbonate, polysulfone, polyethylene naphthalate, polyvinyl chloride, and cyclic hydrocarbon group-containing polyolefin. In addition, one or more kinds of films selected from NiP, NiP alloys, and other alloys are formed on these substrate surfaces by sputtering, vacuum vapor deposition or other physical vapor deposition (PVD) or electrolytic plating. can do. Of course, it goes without saying that the substrate 10 may have a multilayer structure.

  In the present embodiment, as an example, a case where diamond-like carbon (amorphous carbon), which is a carbon-based protective film created by a CVD (chemical vapor deposition) method, is used as the base material 10 will be described.

  On the surface of the substrate 10, there are usually terminal bonds called dangling bonds 12. The dangling bonds 12 include those that are not bonded to other atoms 12a, those that are bonded to OH groups 12b, and those that are hydrogen bonded (adsorbed) to water molecules 12c. Of course, it may be bound (adsorbed) to other molecules.

  Such dangling bonds 12 are found not only in carbon materials but also in all solid materials, and are particularly noticeable in materials having strong covalent bonds.

Before the lubricant application step, the base material 10 is heated (for example, 80 to 200 ° C., 30 minutes or more), the surface of the base material 10 is irradiated with ultraviolet rays (for example, a wavelength of 50 to 350 nm), or The substrate 10 is held in a reduced pressure atmosphere (for example, 1 × 10 ⁻¹ Torr or less), an inert gas atmosphere (for example, nitrogen, argon, etc.), or a low humidity environment (for example, RH 10% or less). It is preferable to desorb molecules (for example, water or the like) or functional groups (for example, OH group or the like) bonded to the dangling bond 12 by, for example. Heating and ultraviolet irradiation are preferably performed in a vacuum, in an inert gas such as nitrogen or argon, or in a low humidity environment (RH 10% or less). Needless to say, the present invention can be implemented even if molecules or functional groups bonded to dangling bonds remain. In addition, it is preferable to set it as the heating temperature of the grade which does not damage a base material, and the intensity | strength of UV irradiation.
It is also preferable to remove organic substances on the surface by ozone treatment.

(Lubricant application process)
Subsequently, as shown in FIG. 2, a lubricant 21 is applied to the surface of the substrate 10 to form a lubricating film. The lubricant 21 may be a compound having an OH group. Here, the OH group is a concept including an OH group contained in a complicated functional group such as a carboxyl group (—COOH) or a phenol group.

  As such a lubricant 21, in addition to hydrocarbons having an OH group, alcohols (for example, erucyl alcohol, ricinyl alcohol, aracidyl alcohol, capryl alcohol, caprin alcohol, polyolefin alcohol, 2-ethylhexyl alcohol, Polyalkylene glycol, etc.), carboxylic acids (eg, aliphatic carboxylic acids, aromatic carboxylic acids, oxocarboxylic acids, etc.), esters having OH groups (eg, thioesters having OH groups, phosphate esters, nitrate esters, etc.) , Ethers having an OH group (for example, polyphenyl ether having OH group, dimethyl ether, ethyl methyl ether, diethyl ether, etc.), silicon compounds having an OH group (for example, silicone oil having an OH group), Having halogen Organic compounds (halogenated ether having OH group, halogenated alcohols having an OH group, a halogenated carboxylic acid having an OH group). In particular, a fluorinated organic compound having an OH group is preferable. For example, a fluorinated ether, a fluorinated alcohol, a fluorinated carboxylic acid, or a fluorinated carboxylic acid having an OH group, such as a perfluoropolyether having an OH group. Alkyl esters, fluorinated diester dicarboxylic acid compounds having an OH group, fluorinated monoester monocarboxylic acid compounds having an OH group, and the like. Among these, a chain halogenated organic compound having an OH group at the terminal, particularly a chain fluorinated organic compound is preferable.

  In particular, among fluorinated ethers having an OH group, fluoropolyethers having an OH group are preferable, and in particular, a compound of the formula (1) known as Fomblin Z, a compound of the formula (2) known as Fomblin Y, Krytox A chain fluoropolyether having an OH group at its end, such as a compound of the formula (3) known as ## STR4 ## and a compound of the formula (4) known as Demnum, is particularly preferred.

_{X-CF 2 -O (-CF 2} -CF 2 -O-) m (-CF 2 -O-) n CF 2 -X (1)
_{X-CF 2 -O (-CF (} CF 3) -CF 2 -O-) m (-CF 2 -O-) n CF 2 -X (2)
_{X-CF 2 -O (-CF (} CF 3) -CF 2 -O-) m CF 2 -CF 2 -X (3)
_{X-CF 2 -CF 2 -O (} -CF 2 -CF 2 -CF 2 -O-) m CF 2 -X (4)

Here, n and m each represent an integer of 1 or more. X _{is, -CF 3, -CH 2 -OH,} -CH 2 - from _p -OH, the group consisting of _{-CH 2 -O-CH (OH)} -CH 2 -OH (-O-CH 2 -CH 2) Any functional group selected, at least one of each compound having a functional group having an OH group. Here, P represents an integer of 1 or more. The molecular weight of the chain fluoropolyether is not particularly limited, but the central molecular weight is preferably about 500 to 4000.

  Needless to say, the lubricant may contain a compound having no OH group, such as a solvent.

  Such a lubricant can be applied by a known method such as a vacuum deposition method, a PVD method, a CVD method, a dipping method (dip method), a spin coating method, a spray coating method, or the like. In addition, as described in the base material preparation step, when the surface of the base material 10 before applying the lubricant is subjected to a cleaning process such as heating in vacuum or inert gas or ultraviolet irradiation. In order to prevent the cleaned surface of the substrate 10 from being contaminated by atmospheric oxygen, moisture, other highly reactive impurities (contaminants), etc. during application, this application may be carried out in a vacuum or under a vacuum. It is preferable to carry out in an active gas.

  The thickness of the lubricating film 20 applied here is not particularly limited, but is preferably about 2 nm or less so that the infrared laser can efficiently reach the interface between the base material 10 and the lubricating film 20 and the vicinity thereof. In the case of multiphoton absorption, the film thickness is not particularly limited.

  Here, if necessary, the lubricant film 20 is heated after application of the lubricant 21 (for example, 80 to 200 ° C., 30 minutes or more), or the lubricant film 20 is irradiated with ultraviolet rays to have the lubricant 21. An OH group or a functional group other than the OH group (for example, an amino group) may be preliminarily bonded to the dangling bond 12 of the substrate 10. Needless to say, the present invention can be sufficiently implemented without heating or ultraviolet irradiation. In addition, it is preferable to set it as the temperature and UV intensity which do not damage the base material 10 and the lubricating film 20.

(Laser irradiation process)
Subsequently, an infrared laser beam is irradiated to the lubricant 21 of the lubricating film 20 so as to excite the vibration of the OH group of the OH group. Specifically, since the OH bond easily absorbs infrared light having a wavelength of about 0.9 to 8 μm as shown in FIG. 3, the energy corresponding to the wavelength of 0.9 to 8 μm can be absorbed. It is preferable to irradiate possible infrared laser. In FIG. 3, the dotted line b is the base line, and the solid line a is the absorption intensity due to the OH bond of the OH group. In particular, irradiation with an infrared laser capable of absorbing energy corresponding to a wavelength of 0.9 to 1.2 μm (range W2 in FIG. 3) and 2.7 to 3.0 μm (range W1 in FIG. 3). It is preferable to do.

  Specifically, in the case of one-photon absorption, for example, infrared laser light having a wavelength of 0.9 to 8 μm may be irradiated, and particularly 0.9 to 1.2 μm or 2.7 to 3.0 μm. Irradiation with an infrared laser beam having a wavelength of On the other hand, in the case of multiphoton absorption in which two or more photons are absorbed, infrared laser light having a wavelength of 0.9 to 8 μm, preferably 0.9 to 1.2 μm, by infrared laser light having a predetermined wavelength. Alternatively, energy corresponding to infrared laser light having a wavelength of 2.7 to 3.0 μm may be absorbed. For example, a plurality of photons whose sum of energy is in the above energy range may be supplied simultaneously or continuously. That is, in the case of multiphoton absorption, light having a longer wavelength is irradiated than in the case of single photon absorption.

  Although the irradiation method of infrared laser light is not particularly limited, for example, a laser irradiation system LS1 as shown in FIG. The laser light L from the laser light source 50 may be collimated by the collimator 56, and the in-plane intensity distribution may be made uniform by the homogenizer 54 and then irradiated to the lubricant 21 of the lubricating film 20. This form is particularly suitable when exciting the vibration of the OH group using one-photon absorption. Examples of the laser light source 50 include a carbon dioxide gas laser and a YAG laser.

  Here, as the homogenizer 54, a known one such as a combination of two lenses or a diffraction grating can be adopted, and a Gaussian distribution type in-plane intensity distribution can be made into a sufficiently flat in-plane intensity distribution. Is preferred.

  As shown in FIG. 4A, the incident angle of the laser beam to the lubricating film 20 is most effective at 90 °. However, when the light source or the like needs to be protected from the reflected light, the incident angle The angle can be 30 to 60 °.

  What is necessary is just to make the spot diameter of the infrared laser beam irradiated to the lubricating film 20 and the base material 10 correspond to the area of the lubricating film 20. When the irradiation area is very large, the beam spot may be scanned relative to the lubricating film 20.

  Further, a laser irradiation system LS2 as shown in FIG. This irradiation system is particularly suitable for multiphoton absorption such as two-photon absorption. The laser light converted into parallel light by the collimator 56 is scanned by the two-dimensional scanning optical system 56, and the scanned laser light is condensed by the objective lens 58 and the surface of the substrate 10 or the base of the lubricating film 20. Irradiation is performed so that a focal point is formed in the portion on the material 10 side. Thereby, it is possible to concentrate and irradiate infrared laser light on a portion near the interface in the lubricant 21.

  The two-dimensional scanning optical system 56 includes, for example, two galvanometer mirror scanners, and is controlled by a scanner driver (not shown) to scan the laser spot on the lubricating film 20 two-dimensionally on the substrate. Note that the substrate side may be scanned.

  The laser light source 50 may be the above-described light source, but it is preferable to use a laser light source that supplies an ultrashort pulse laser such as a femtosecond laser in order to enable multiphoton absorption.

In any case, the irradiation intensity of the infrared laser light is not particularly limited, but is preferably 60 J / cm ² or less in order to reduce the influence on the base material and the influence of evaporation of the lubricant, It is preferably 0.01 mJ / cm ² or more so as to cause sufficient vibration excitation. The bond energy of the OH group is about 428 to 510 kJ / mol, and in order to break the bond of OH, it is necessary to give an energy exceeding this, but if the energy is too strong, evaporation of the lubricant and unnecessary reaction, Since problems such as damage to the substrate occur, the laser irradiation energy needs to be optimized for each sample.

When irradiating pulsed laser light as infrared laser light, the irradiation intensity of the laser light is 60 J / cm ² or less, the pulse width is 0.1 to 1 ms, the number of pulses is 1 to 10, and the pulse frequency is 10 to 50 Hz. By doing so, an unnecessary temperature rise in the laser processing portion can be suppressed, which is preferable.

  There may be a plurality of laser light sources.

  And the vibration of the OH group of the OH group of the lubricant is excited by irradiation with such infrared laser light. Accordingly, the reactivity between the OH group of the lubricant 21 and the surface of the substrate 10 is increased, and it becomes easy to chemically bond the lubricant 21 to the surface of the substrate 10.

  Specifically, the following mechanism can be considered. That is, the vibration of the OH group of the OH group of the lubricant 21 is excited by the irradiation of the infrared laser light, so that the OH group is activated and the dissociation between O and H occurs, resulting in dangling on the substrate surface. It becomes easy to bond with the bond 12. Therefore, for example, as shown in FIG. 5, the lubricant 21 can be easily covalently bonded to the dangling bonds 12 on the surface of the base material 10 through O atoms derived from OH groups. Therefore, it is considered that the durability of the lubricating film 20 is increased.

  In particular, such immobilization with infrared laser light can selectively heat OH groups compared to heat treatment, UV treatment, etc., so that effective heating with less energy is possible and short-time treatment is possible. Is possible. Therefore, thermal deterioration, thermal strain, unnecessary thermal decomposition, material evaporation, and the like can be reduced. Moreover, according to the two-photon absorption using the apparatus as shown in FIG. 4B, the surface portion of the base material can be selectively processed, which is more efficient.

  Here, if necessary, after the infrared laser irradiation, the lubricating film 20 is heated (for example, 80 to 200 ° C., 30 minutes or more), or the lubricating film 20 is irradiated with ultraviolet rays to An OH group or a functional group other than the OH group (for example, an amino group) can be supplementarily bonded to the dangling bond 12 of the substrate 10. Needless to say, the present invention can be sufficiently implemented without heating or ultraviolet irradiation. In addition, it is preferable to set it as the temperature and UV intensity which do not damage the base material 10 and the lubricating film 20.

(Cleaning process)
Subsequently, unnecessary lubricant in the lubricant 21 of the lubricating film 20, that is, lubricant 21 that is not fixed to the surface of the base material 10, unnecessary by-products, foreign matters, free oil, etc. are lubricated as necessary. A cleaning process for removing the film 20 is performed (see FIG. 6).

Specifically, an organic solvent such as a fluorine-based solvent, ether, hexane, or alcohol, or a cleaning medium such as water or CO ₂ (gas, supercritical fluid) is used, and these cleaning medium and the lubricating film 20 are brought into contact with each other. Just do it. At the time of cleaning, ultrasonic vibration may be applied to the lubricating film 20.

  If removal of low molecular weight substances is the main purpose, cleaning by volatilization by evacuation or heating is also possible. Thereby, it will be in the state where there are few lubricants 21 which are not couple | bonded with the surface of the base material 10. FIG. The thickness of the lubricating film after cleaning is not particularly limited, but is preferably 2 nm or less.

  If necessary, the lubricant is heated as described above after cleaning (for example, 80 to 200 ° C. for 30 minutes or more), or the lubricant is irradiated with ultraviolet rays to leave residual OH groups or Other functional groups can be bonded to the dangling bonds 12 of the substrate 10.

  In this way, the lubricating film forming method according to the preferred embodiment of the present invention is completed.

  (Magnetic head slider and magnetic recording medium)

  Next, a method for manufacturing a magnetic head slider and a magnetic recording medium using such a method for forming a lubricating film will be described.

  FIG. 7 is a schematic configuration diagram of the hard disk drive HDD. The hard disk drive HDD mainly includes a disk-shaped magnetic recording medium 120 and a magnetic head slider 110.

  The magnetic recording medium 120 has a disk shape, and a magnetic recording layer 129 is provided inside. In addition, a motor 130 for rotating the magnetic recording medium 120 is connected to the central portion of the axis of the magnetic recording medium 120, and the magnetic recording medium 120 is rotated around the axis.

  The magnetic head slider 110 has a substantially plate shape, is disposed to face the surface S of the magnetic recording medium 120, and usually from the surface S of the magnetic recording medium 120 due to an air flow generated as the magnetic recording medium 120 rotates. Slightly rise.

  The magnetic head slider 110 includes a magnetic head 140. The magnetic head 140 has a writer (not shown) that writes data to the magnetic recording layer 129 of the magnetic recording medium 120 and / or a reader (not shown) that reads data from the magnetic recording layer 129. A surface facing the surface S of the magnetic recording medium 120 of the magnetic head slider 110 is a medium facing surface ABS. The magnetic head slider 110 is connected to a head drive unit 113 that moves the magnetic head slider 110 to a desired location on the surface of the magnetic recording medium 120.

  As shown in the partial cross-sectional view of FIG. 8A, the magnetic head slider 110 has a base layer 116, a protective film 117, and a lubricating film 118 formed on a substrate 115.

Examples of the material of the substrate 115 include ceramic materials such as alumina / titanium carbide (Al ₂ O ₃ —TiC) sintered body, metal oxides such as alumina Al ₂ O ₃ , metal materials such as Ti, Si, and the like. And non-magnetic insulating materials such as non-metallic inorganic materials such as C.

  Examples of the material of the base layer 116 include silicon and silicon nitride.

Examples of the material for the protective film 117 include carbon materials such as amorphous carbon (for example, diamond-like carbon, graphite carbon, hydrogenated carbon, nitrogen-added carbon, and fluorine-added carbon) and various metal-added carbons, WC, WMoC, ZrN, and BN. Inorganic materials such as B ₄ C, SiO ₂ and ZrO ₂ are suitable, and the thickness can be, for example, about 1 to 3 nm. Here, the protective film 117 corresponds to the above-mentioned “base material”.

  The lubricating film 118 corresponds to the lubricating film 20 described above. Although the material of the lubricant 21 is not particularly limited, a fluorinated organic compound having an OH group such as a fluoropolyether having an OH group can be particularly preferably used.

  As a method for manufacturing such a magnetic head slider 110, after forming the magnetic head 140 on a substrate by a known method, the medium facing surface ABS is formed and polished, and then a vapor deposition method (vacuum vapor deposition method, sputtering method). The underlayer 116 and the protective film 117 are formed by a known method such as a method or a CVD method. And the formation method of the above-mentioned lubricating film should just be implemented by using this protective film 117 as a base material.

  Next, the magnetic recording medium 120 will be described. As shown in the partial cross-sectional view of FIG. 8B, the magnetic recording medium 120 has a base layer 126, a magnetic recording layer 129, a protective film 127, and a lubricating film 128 formed on a substrate 125.

  Examples of the material of the substrate 125 include glass, aluminum, Al-based alloy glass, plastic, ceramic, carbon, silicon, and an Si single crystal substrate having an oxidized surface. In the case of a flexible disk medium or a magnetic tape medium, for example. Examples thereof include synthetic resins such as polyacetate.

  There are no restrictions on the material of the underlayer 126, and in the case of a hard disk magnetic recording medium, Cr, Ni-P, etc. can be exemplified. Further, as the material of the base film 126, in the case of a horizontal magnetic recording medium, a nonmagnetic material such as a Cr alloy can be cited. Is mentioned. In particular, in the case of a perpendicular magnetic recording medium, Ti, Ta, W, Cr, Pt are further provided below the soft magnetic underlayer to improve the crystallinity of the soft magnetic underlayer or the adhesion to the substrate. Or an alloy containing these, or an underlayer made of a material such as an oxide or nitride thereof, and an intermediate layer between the soft magnetic underlayer and the recording layer. , Pd, W, Ti, Ta, Cr, Si, an alloy containing these, or an intermediate layer made of a nonmagnetic material such as an oxide or nitride thereof.

  As a material of the magnetic recording layer 129, for example, a material containing Co as a main component, containing at least Pt, optionally containing Cr, and further containing an oxide can be given.

  Examples of the material of the protective film 127 include a carbon material such as diamond like carbon having a thickness of about 1 to 10 nm. Here, the protective film 127 corresponds to the “base material” described above.

  The lubricating film 118 corresponds to the aforementioned lubricating film 20A. The lubricant is not particularly limited, but a fluorinated organic compound having an OH group such as a fluoropolyether having an OH group is particularly preferable. The molecular weight of the fluorinated organic compound is not particularly limited, but the central molecular weight is preferably about 500 to 4000.

  As a method for manufacturing such a magnetic recording medium 120, a base layer 126, a magnetic recording layer 129, and a protective film 127 are sequentially formed on a substrate 125 by a known method, and the above-described lubricating film forming method is performed. Good.

  According to these inventions, since heating is not essential, thermal demagnetization of the magnetic head 140 and the magnetic recording layer 129 can be suppressed, which is preferable. In addition, when such a magnetic head slider 110 or magnetic recording medium 120 is used, the durability of the lubricating film 20 becomes extremely high, so that a hard disk drive with excellent reliability and life can be obtained. Of course, the same effect can be obtained even when a tape medium or a flexible disk (FD) is used as the magnetic recording medium.

(Examples 1-3)

On the Co substrate, diamond-like carbon was formed in a thickness of 3 nm under vacuum to obtain a base material. Thereafter, a lubricant was applied to the surface of the substrate so as to have a thickness of about 1.2 nm to obtain a lubricating film. Fomblin Z of the formula (1) was used as the lubricant. Thereafter, the lubricating film was irradiated with pulsed infrared laser light (Nd-YAG laser) having a wavelength of 1.064 μm. The laser pulse width was 0.3 ms. The laser irradiation intensity was 9.6, 11.6, and 13.5 J / cm ^{2 in} the order of Examples 1 to 3, respectively. In this way, a sample substrate having a lubricating film was obtained.
(Comparative Example 1)

A sample substrate was obtained in the same manner as in Example 1 except that laser irradiation was not performed.
(Evaluation)

  A scratch test of the lubricating film (thickness: about 1.1 nm) of each sample substrate was performed with a load of 3.98 mN using a diamond tip with an indenter tip of 8 μm in diameter. The depth D and width W of the scratch were measured with a scanning ellipsometer. The results are shown in FIG.

  Moreover, about Example 3 and a comparative example, about the sample surface which is not carrying out a scratch test, mass analysis is carried out with a TOF type secondary ion mass spectrometer (SIMS), and the characteristic CF bond in a lubricant, The ratio with Co atoms present in the magnetic layer of the magnetic recording medium was obtained. The results are shown in FIG.

  As can be understood from FIG. 9, in Examples 1 to 3, sufficient durability of the lubricating film was exhibited as compared with the comparative example in which laser irradiation was not performed.

  Further, as can be understood from FIG. 10, it has been clarified that in the example, the concentration (surface adsorption density) of the lubricant fixed on the base material can be increased as compared with the comparative example. Since the mass spectrometry is performed in a vacuum, the lubricant on the surface of the base material that has not been laser-processed, that is, the lubricant that is not bonded to the base material evaporates. Therefore, it can be considered that the lubricating film thickness of the comparative example (laser intensity 0) is smaller than the lubricating film thickness of the laser machined portion in the example. Furthermore, in the examples, diamond-like carbon that is the protective film and the lubricant molecules react strongly by laser processing, and the surface adsorption density of the lubricant molecules is increased compared to the comparative example. It is possible.

FIG. 1 is a schematic cross-sectional view showing a preferred embodiment of the present invention. FIG. 2 is a schematic cross-sectional view following FIG. 1 showing a preferred embodiment of the present invention. FIG. 3 is a graph showing the absorption wavelength distribution of OH bonds of OH groups. 4A and 4B show an example of a laser irradiation system. FIG. 4A shows a system in which a laser beam is enlarged and irradiated to a spot having a predetermined area. FIG. 4B shows a laser beam condensed and irradiated. It is a system. FIG. 5 is a schematic cross-sectional view subsequent to FIG. 2 showing a preferred embodiment of the present invention. FIG. 6 is a schematic cross-sectional view subsequent to FIG. 5 showing a preferred embodiment of the present invention. FIG. 7 is a schematic diagram showing a hard disk device according to the present invention. 8A and 8B are partial cross-sectional views of FIG. 7, in which FIG. 8A is a cross-sectional view of a slider, and FIG. 8B is a cross-sectional view of a magnetic recording medium. FIG. 9 is a table showing the conditions of Examples 1 to 3 and the comparative example and the results of the scratch test. FIG. 10 is a graph showing the concentration (density) of the lubricant fixed to the substrate surface in Example 3 and Comparative Example.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 10 ... Base material, 21 ... Lubricant, 20 ... Lubricating film, 54 ... Homogenizer, 110 ... Magnetic head slider, 120 ... Magnetic recording medium.

Claims (10)

A method for forming a lubricating film comprising a step of irradiating a lubricant having an OH group applied to a surface of a substrate with an infrared laser beam that excites vibration of an OH bond of the OH group ,
The lubricant is a chain fluoropolyether having an OH group at its end,
In the step, an infrared laser beam having a wavelength of 0.9 to 1.1 μm or a wavelength of 2.7 to 3.0 μm is irradiated, or a wavelength of 0.9 to 1.1 μm or more by multiphoton absorption by the infrared laser beam. A lubricating film forming method for absorbing energy corresponding to infrared light having a wavelength of 2.7 to 3.0 μm. In the step, multi-photon absorption is performed, and the infrared laser light is irradiated so that a focal point of the infrared laser light is formed on the surface of the base material or a portion of the lubricant on the base material side. The method for forming a lubricating film according to claim 1 . The method for forming a lubricating film according to claim 1, wherein an infrared laser beam transmitted through a homogenizer is used as the infrared laser beam. The lubricating film forming method according to claim 1 , wherein the lubricant is a layer having a thickness of 2 nm or less. The method for forming a lubricating film according to any one of claims 1 to 4 , wherein an irradiation intensity of the infrared laser light is 60 J / cm ² or less. Infrared pulse laser light is irradiated as the infrared laser light, the intensity of the laser light is 60 J / cm ² or less, the pulse width is 0.1 to 1 ms, the number of pulses is 1 to 10, and the pulse frequency is 10 to 50 Hz. lubricating film forming method according to any one of claims 1 to 4. The method for forming a lubricating film according to any one of claims 1 to 6 , wherein a surface temperature of the base material is maintained at 200 ° C or lower during the infrared laser light irradiation. Surface of the substrate, the lubricating film forming method according to any one of claims 1 to 7 which is formed by a carbon material. The manufacturing method of the magnetic recording medium which performs the lubricating film formation method in any one of Claims 1-8 with respect to the said lubricant agent apply | coated to the surface of a magnetic recording medium. The manufacturing method of the magnetic head slider which performs the lubricating film formation method in any one of Claims 1-8 with respect to the said lubricant agent apply | coated to the surface of a magnetic head slider.

Images