JP2006031853A - Magnetic recording device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a magnetic recording device which can effectively prevent head crash in not only room temperature environment but also cold environment where the fluidity of lubricant on discrete track medium deteriorates. <P>SOLUTION: The magnetic recording device having a magnetic recording medium which has a substrate, a magnetic layer formed on the substrate and lubricants applied to a surface and furthermore, includes a data area including a pattern of a magnetic layer which makes a recording track in a face of a magnetic layer, a servo area of length s formed between data areas along with a track length direction including a pattern of the magnetic layer utilized as a servo signal, and a non-magnetism layer which separates patterns of these magnetic layers; a magnetic head supported in the floating state above a magnetic recording medium; a head slider in which the length L of the slider moving direction of a pad of which surface facing the recording medium approaches most to above magnetic recording medium is the length s of the above servo area or shorter; and an actuator. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a magnetic recording apparatus using a discrete track medium.

  In recent years, in order to cope with further increase in the density of magnetic recording media, discrete track media in which adjacent recording tracks are separated by a guard band made of a non-magnetic material to reduce magnetic interference between adjacent tracks have attracted attention. Collecting. In order to put such a discrete track medium into practical use, it is required to satisfy various requirements. For example, it is required to effectively prevent head crashes not only in a room temperature environment but also in a cold environment where the fluidity of a lubricant on a discrete track medium deteriorates. In order to meet these requirements, it is necessary to consider the design of the head slider as well as the design of the discrete track medium.

  Conventionally, for flying head sliders used for discrete track media with uneven surfaces, the length of the control signal recording area (servo area) in the circumferential direction (track length direction) is set to the length of the head slider. A magnetic disk device that has a length not exceeding 3/10 has been proposed (Patent Document 1). It is described that in such a magnetic disk device, fluctuations in the flying height of the head slider can be suppressed.

However, this magnetic disk device is intended for a magnetic disk having irregularities and a head slider having a so-called side rail. For this reason, the above design guidelines are not generally applicable to any magnetic disk. As will be described later, inconvenience occurs in the magnetic disk device to which the above design guideline is applied.
Japanese Patent Laid-Open No. 9-204652

  An object of the present invention is to provide a magnetic recording apparatus that can effectively prevent head crashes not only in a room temperature environment but also in a cold environment where the fluidity of a lubricant on a discrete track medium deteriorates.

  A magnetic recording apparatus according to an aspect of the present invention includes a substrate, a magnetic layer formed on the substrate, and a lubricant applied to the surface, and further, a magnetic layer forming a track in the plane of the magnetic layer. A data area including a layer pattern, a servo area having a length s formed between data areas along a track length direction including a magnetic layer pattern used as a servo signal, and a pattern of these magnetic layers A rotatable magnetic recording medium including a nonmagnetic layer to be separated; a head slider having a magnetic head attached to a suspension attached to an actuator arm and supported in a floating state on the magnetic recording medium. Thus, the length L in the slider traveling direction of the pad closest to the magnetic recording medium when flying on the medium facing surface is equal to or less than the length s of the servo area. A head slider; characterized in that said actuator arm equipped with a actuator for moving in a radial direction of the magnetic recording medium.

  According to the present invention, it is possible to increase the restoration rate of the lubricant in the servo region, and it is possible to realize a high-density magnetic recording apparatus that can operate even in a cold environment where the restoration of the lubricant is difficult.

Example 1
A magnetic recording apparatus using a discrete track medium according to an embodiment of the present invention will be described with reference to FIG. The magnetic recording apparatus includes a housing 70, a magnetic disk 71, a head slider 76 including a magnetic head, a head suspension assembly (suspension 75 and actuator arm 74) that supports the head slider 76, and a voice coil motor ( VCM) 77 and a circuit board.

  The magnetic disk 71 is attached to a spindle motor 72 and rotated, and various digital data are recorded by a perpendicular magnetic recording system. The magnetic head incorporated in the head slider 76 is a so-called composite head, and includes a single magnetic pole structure write head and a read head using a shield type MR reproducing element (GMR film, TMR film, etc.). A suspension 75 is held at one end of the actuator arm 74, and the head slider 76 is supported by the suspension 75 so as to face the recording surface of the magnetic disk 71. The actuator arm 74 is attached to the pivot 73. A voice coil motor (VCM) 77 is provided at the other end of the actuator arm 74. A head suspension assembly is driven by a voice coil motor (VCM) 77 to position the magnetic head at an arbitrary radial position of the magnetic disk 71. The circuit board includes a head IC, and generates a drive signal for a voice coil motor (VCM), a control signal for controlling reading and writing by the magnetic head, and the like.

  FIG. 2 shows a cross-sectional view of a magnetic disk according to an embodiment of the present invention. The magnetic disk shown in FIG. 2 is obtained by depositing a soft magnetic underlayer (SUL) 12, a perpendicular magnetic recording layer 13, and a protective layer 14 on a disk substrate 11 and applying a lubricating layer 15 on the protective layer 14. . The perpendicular magnetic recording layer 13 is separated by a nonmagnetic layer 16 and formed in a predetermined pattern. The disk substrate 11 in the present embodiment is made of, for example, glass and has a diameter of 0.85 inch. In order to deposit each layer on the substrate, sputtering, vacuum evaporation, electrolytic plating, or the like can be used.

  FIG. 3 is a plan view schematically showing the surface of the perpendicular magnetic recording layer 13. As shown in FIG. 3, servo areas 22 and data areas 23 are alternately formed in the recording track area 21 formed along the circumferential direction. As shown in this figure, the length of the servo area 22 is represented as s. User data is recorded in the data area 23 as magnetic information. In addition, data regions 23 and nonmagnetic layers (guard bands) 24 are alternately formed along the radial direction. Both the data region 23 and the nonmagnetic layer (guard band) 24 are formed extending in the circumferential direction. Although not shown in FIG. 3, a magnetic layer pattern used as a servo signal is formed in the servo region 22. The guard band may not be in the servo area.

  The magnetic recording medium schematically shown in FIGS. 2 and 3 was produced as follows.

<Stamper production>
First, a master plate from which the pattern was based was prepared.
A photosensitive resin was applied on the Si substrate, an electron beam was applied to the photosensitive resin layer to form a latent image, and the latent image was developed to form a concavo-convex pattern. The concavo-convex pattern was formed using an exposure apparatus having a signal source for irradiating the photosensitive resin on the substrate with an electron beam at a predetermined timing and a stage for moving the substrate with high precision in synchronization with the signal source. . A Ni conductive film was formed on the prepared resist master by an ordinary sputtering method. Next, a nickel electroformed film was formed on the conductive film by electroforming. The liquid used for electroforming was Showa Chemical Co., Ltd. high concentration nickel sulfamate plating solution (NS-160). The thickness of this electroformed film was 300 μm. Thereafter, the electroformed film is peeled off from the resist master, thereby obtaining a stamper provided with the conductive film, the electroformed film and the resist residue. Next, the resist residue is removed by an oxygen plasma ashing method.

  The father stamper thus obtained can be used as an imprint stamper. The above-mentioned electroforming process was repeated on this father stamper, and a large number of stampers were duplicated. First, an oxide film was formed on the surface of the father stamper by passivation using an oxygen plasma ashing method similar to the step of removing the resist residue. Thereafter, a nickel electroformed film was formed by the same method as described above by electroforming. Thereafter, the electroformed film was peeled off from the father stamper to obtain a mother stamper which is an inverted type of the father stamper. Ten or more mother stampers having the same shape were obtained by repeating the process of obtaining the mother stamper from the father stamper. Thereafter, in the same manner as the procedure for obtaining the mother stamper from the father stamper, an oxide film was passivated on the mother stamper surface, and an electroformed film was formed and peeled to obtain a sun stamper having the same uneven shape as the father stamper.

<Imprint>
After ultrasonic cleaning of the sun stamper with acetone for 5 minutes, fluoroalkylsilane [CF ₃ (CF ₂ ) ₇ CH ₂ CH ₂ Si (OMe) ₃ ] was soaked in a solution diluted to 2% with ethanol for 30 minutes or more, and the solution was blown off with a blower. The above magnetic recording medium is coated with a resist (Rohm & Haas Electronic Materials Co., Ltd., trade name S1818 diluted 5 times with propyleneglycol monomethyl ether acetate (PGMEA), or S1801) with a spin coater. The pattern was transferred to the resist by pressing the formed stamper at 450 bar for 60 seconds. Thereafter, the stamper was peeled off, and the uneven surface shape was cured by UV irradiation for 5 minutes, and then heated at 160 ° C. for 30 minutes.

<Medium etching>
In order to remove the resist residue in the recesses on the magnetic recording medium, RIE with oxygen gas was performed. Subsequently, the magnetic recording medium is etched by Ar ion milling. In order to eliminate damage to the ferromagnetic recording layer and suppress reattachment, etching was performed while changing the ion incident angle between 30 ° and 70 °. After etching the magnetic material, oxygen RIE was used to remove the etching mask. After processing the magnetic material, a carbon protective film was formed as a protective film. A lubricant was applied to the produced medium by a dip method.

  Through the above process, a magnetic recording medium having surface irregularities can be produced. For example, the following steps are used to obtain a magnetic recording medium having a substantially flat surface as shown in FIG.

  The stamper manufacturing process is the same as described above. In the imprint process, SOG (Spin On Glass) was applied to the magnetic recording medium with a spin coater. Depending on the chemical structure of the siloxane, SOG uses silica glass, alkylsiloxane polymer, alkylsilsesquioxane polymer (MSQ), hydrogenated silsesquioxane polymer (HSQ), hydrogenated alkylsiloxane polymer (HOSP). ) Etc. Here, T-7 manufactured by Tokyo Ohka Kogyo Co., Ltd. and FOX manufactured by Dow Corning Co., Ltd., diluted 5-fold with methyl isobutyl ketone (MIBK) were used. After applying SOG, it was placed in an oven, pre-baked at 100 ° C. for 20 minutes, the solvent in SOG was blown off, and the stamper was pressed at 450 bar for 60 seconds to transfer the pattern onto the resist.

Next, in the etching process, residue removal of the SOG film was performed using an ICP (Inductively Coupled Plasma) etching apparatus. SF ₆ was used as an etching gas. The milling process of the magnetic recording medium is the same as described above.

  After milling, SOG similar to the SOG used for the resist was applied with a spin coater and embedded. Thereafter, etching back was performed until the magnetic film appeared again by milling.

For filling, a process of forming a film of SiO ₂ , Al ₂ O ₃ , Ta ₂ O ₅ or the like by a normal sputtering method and then etching back by milling can be used. Any material that can be sputtered can be used as the material of the dielectric portion.

  Note that a medium having unevenness on the surface can also be produced by increasing the amount of etch back.

  FIG. 4 shows the pattern of the perpendicular magnetic recording layer in the servo area and the data area in more detail. As shown in FIG. 4, the servo area 22 includes a preamble, an address area 31, an ABCD burst area 32, a mirror portion, and the like. These servo signals are formed by the perpendicular magnetic recording layer 13 and the nonmagnetic layer 16, and the magnetic head reads the servo signal from the change in magnetic flux caused by the presence or absence of the perpendicular magnetic recording layer 13.

  FIG. 5 shows a schematic diagram of the burst region 32. Reference numeral 35 denotes an area for generating one unit of burst signal. When the region 35 is a magnetic material, the surrounding region is a non-magnetic material. Conversely, when the region 35 is a non-magnetic material, the surrounding region is a magnetic material. Whether the region 35 is magnetic or non-magnetic does not affect the effect of the present invention, and the material of the region 35 is determined from the viewpoint of manufacturing cost and signal efficiency.

  On the other hand, FIG. 6 is a plan view showing an example of the medium facing surface (ABS surface) of the head slider 76. The ABS surface of the head slider 76 is not limited to the form shown in FIG. 6, and other forms may be used. In this figure, portions having the same height on the ABS surface are indicated by the same hatching, and 41, 42, 43, and 44 are higher in this order. The head slider 76 moves in the direction of the arrow D relative to the magnetic disk 71 (that is, the magnetic disk 71 moves in the direction opposite to the arrow D). In FIG. 6, the left end is the leading edge, the right end is the trailing edge, and the magnetic head 80 is provided on the trailing edge. During operation, air flows in from the leading edge and flows out to the trailing edge, so that a positive pressure is generated at the pad on the ABS surface of the head slider 76 and the head slider 76 floats on the magnetic disk 71. At this time, the pad 45 having the smallest area (hereinafter referred to as a trailing pad) comes closest to the magnetic disk 71 in the region within 30% of the total length of the head slider 76 from the trailing edge of the ABS surface of the head slider 76, and the trailing. Most of the positive pressure (levitation force) is generated in the pad 45. In order to balance the flying force on the trailing pad 45, a flying force or a suction force is generated by the other pads and recesses on the ABS surface of the head slider 76. As shown in FIG. 6, the length of the trailing pad 45 in the slider traveling direction is represented by L.

  The magnetic recording apparatus shown in FIG. 1 was manufactured using the magnetic disk having the configuration shown in FIGS. 2 to 5 and the head slider 76 having the configuration shown in FIG.

  Japanese Patent Laid-Open No. 9-204652 (Patent Document 1) discloses a technique for defining a ratio between the length of a head slider and the length of a servo area. According to this technology, in order to suppress the difference in flying height between the servo area and the track area, it is necessary to make the pad on the ABS surface (side rail in Patent Document 1) that generates the slider flying force larger than the servo area. is there. According to this technique, the length L of the trailing pad was set to 100 μm, the length s of the servo area was set to 80 μm, and a magnetic recording device with L> s was produced.

  First, a reproduction experiment was performed using a slider manufactured with a low flying height specification for high density recording. As a result, a head crash occurred when the operation was continued for 1000 hours. While examining the cause, it was found that the thickness of the lubricant was reduced in the servo region. In other words, when the thickness distribution of the lubricant was observed over the entire disk surface using an OSA (Optical Surface Analyzer; manufactured by Candela Instruments, USA), it was found that the lubricant was thin particularly in the servo area of the track where many heads passed. I found it almost gone. Since this observation technique cannot determine the thickness of the lubricant, the specific thickness of the lubricant is not known. However, it was estimated that the decrease in lubricant thickness in the servo region was a direct cause of head crash.

  Therefore, the reason why the thickness of the lubricant decreased in the servo region was investigated by a fluid dynamics simulation. As a result, the following was found. As shown in FIGS. 4 and 5, the servo area 22 has isotropic and nonmagnetic patterns. Although the preamble of the servo area 22 has a continuous pattern in the disk radial direction, it can still be said to be isotropic compared to a data area having anisotropy in the circumferential direction as a whole. As a result of observing the surface of the magnetic disk 71 in detail, it was found that the properties of the carbon protective film 14 were slightly different between the magnetic material and the non-magnetic material, and therefore the adhesion state of the lubricant 15 was different. As a result, the adhesion state of the lubricant 15 is different between the servo area and the data area. Specifically, with respect to a phenomenon (referred to as a restoration process) in which the lubricant is supplied from the surroundings and the film thickness of the lubricant is restored after the lubricant becomes thin due to light contact of the head slider 76 or the like. Anisotropy is observed in the restoration speed (coefficient of friction) of the agent. In the data area 23, the restoration speed is fast in the track length direction. On the other hand, in the servo area 22, the repair speed is isotropic, but the repair speed is slower than that of a conventional magnetic disk in which the magnetic material is not processed.

  As described above, on the medium, the greatest levitation force is generated immediately below the trailing pad. That is, the lubricant is strongly pressed by the size of the trailing pad. When the length L of the trailing pad in the slider traveling direction is larger than the length s of the servo area, the lubricant in the entire servo area under the trailing pad is pushed. Most of the pushed lubricant moves to the data area, where it is carried farther due to the higher speed of lubricant movement. Since the surplus lubricant moves to the distant part of the data area in this way, the restoration of the lubricant is delayed after the head slider passes. Further, since the amount of the lubricant pushed in the radial direction of the servo region is small in the first place and the moving speed is slow, the restoration of the lubricant is also delayed. It is considered that the lubricant thickness in the servo area decreases as this phenomenon is repeated many times.

  Based on the above knowledge, we devised a magnetic recording device that does not reduce the lubricant thickness in the servo region. That is, as shown in FIG. 7, a magnetic recording apparatus was produced in which the relationship between the length L of the trailing pad in the slider traveling direction and the length s of the servo area was L <s. 7 indicates a region where a high pressure is generated by the trailing pad 45, and the length L ′ of the region 45 ′ is substantially the same as the length L of the trailing pad 45. It is. Specifically, L was set to 70 μm and s was set to 100 μm. The flow of the lubricant generated at this time is indicated by an arrow R.

  The lubricant pushed away by the pressure by the trailing pad 45 flows in the lateral direction reflecting the isotropic property of the repair speed in the servo region 22, and as a result, the lubricant becomes thick on the lateral side of the region 45 ′. The internal pressure increases. For this reason, as the trailing pad 45 passes, the lubricant flows into the region where the lubricant on the trailing side (left side in FIG. 8) is thin, and is immediately repaired. As described above, in the magnetic recording device of L <s, unlike the case of L> s, the restoration speed of the lubricant is high.

  In order to confirm the above effect, the following experiment was conducted. Magnetic recording devices having different values of L / s were manufactured, and the rate of occurrence of errors due to a delay in lubricant repair (defined as the repair error rate) was examined. Here, the repair error rate was measured as follows. In order to accelerate the lubricant repair error, the magnetic recording apparatus was installed in a low-temperature environment of 0 ° C. to conduct experiments. The head slider was passed for 2 hours continuously on the same track. An AE sensor is attached to the head slider so that the occurrence of vibration due to uneven thickness of the lubricant or light contact can be monitored. A track in which a signal corresponding to an intensity five times the noise level was generated by the AE sensor was determined as an error-occurring track. This experiment was performed at 5 different radial locations and averaged. The result is shown in FIG. As can be seen from FIG. 8, it was found that no error occurred if L ≦ s.

(Example 2)
From the knowledge of Example 1, it is conceivable that irregularities on the surface of the medium also affect the restoration speed of the lubricant. Therefore, the process of filling and planarizing the nonmagnetic layer 16 was changed to produce a magnetic disk in which the thickness of the nonmagnetic layer 16 was thinner than the thickness of the perpendicular magnetic recording layer 13 as shown in FIG. In FIG. 9, t is the unevenness difference between the protective layer on the perpendicular magnetic recording layer 13 and the protective layer on the nonmagnetic layer 16. The unevenness t on the surface of the protective film 14 can be measured by AFM or the like. Generally, the magnetic disk surface has a roughness of about 0.3 to 1 nm. This roughness is generally described by the average roughness Ra. The unevenness difference t may be smaller than Ra. FIG. 10 shows an example where Ra is larger than t. Concavities and convexities on the convex and concave portions are shown with the vertical axis highlighted. In this figure, the unevenness difference t is 0.4 nm.

  Magnetic disks having concavo-convex differences t of 0.4, 5, 20, 50, and 80 nm were produced, magnetic recording devices were produced in the same manner as in Example 1, and the repair error rate was similarly evaluated. At that time, the structure of the head slider was changed to produce head sliders with flying heights of 7, 12, 16, and 22 nm on smooth magnetic disks, respectively, and evaluation was performed using each head slider. The result is shown in FIG. In FIG. 11, ◯ indicates that the repair error rate is less than 10%, and × indicates that the repair error rate is 10% or more.

  As can be seen from FIG. 11, in the case of a magnetic disk having a concavo-convex difference of 20 nm, the repair error rate can be made less than 10% by using a head slider with a designed flying height of 16 nm. Therefore, the repair error rate can be further reduced in the magnetic disk having the unevenness difference of 20 nm or less. In particular, it was found that in the case of a magnetic disk having an unevenness difference smaller than 5 nm, a head slider having a design flying height of 12 nm or less can be used, and a high-density magnetic recording apparatus can be provided.

Example 3
The magnetic disk shown in FIG. 12 was manufactured by changing the manufacturing process as follows. A photoresist was spin coated on the glass substrate 11. A stamper having a pattern corresponding to the servo area 22 and the data area 23 shown in FIG. 3 was pressed against the photoresist to transfer the stamper pattern to the resist. Resist residues at the bottom of the recesses were removed by an oxygen RIE process to expose the glass substrate surface. A portion of the glass substrate 11 was etched by an RIE process using CF ₄ gas to form a recess having a depth of about 50 nm. On this glass substrate 11, a soft magnetic underlayer 12, a perpendicular magnetic recording layer 13, and a protective layer 14 were formed as continuous films. In this case, since the protective layer 14 exists in the concave portion of the perpendicular magnetic recording layer 13, the perpendicular magnetic recording layer 13 is separated by a part of the nonmagnetic protective layer 14 in substantially the same plane. A lubricant 15 was applied on the protective layer 14.

  In addition, the magnetic disk shown in FIG. 13 was manufactured by changing the manufacturing process as follows. In the same manner as described above, a recess having a depth of about 50 nm was formed on the surface of the glass substrate 11. A soft magnetic underlayer 12 and a perpendicular magnetic recording layer 13 were both formed as continuous films on the glass substrate 11. A nonmagnetic layer 16 was embedded in the concave portion of the perpendicular magnetic recording layer 13 and planarized. In this case, the perpendicular magnetic recording layer 13 is separated by the nonmagnetic layer 16 in substantially the same plane. A lubricant 15 was applied on the protective layer 14.

  Using these two types of magnetic disks, magnetic recording devices were produced in the same manner as in Examples 1 and 2, and the repair error rate was evaluated. As a result, the same results as in FIGS. 8 and 11 were obtained. As shown in FIG. 12 and FIG. 13, it was found that even in a magnetic recording apparatus having a magnetic disk using a substrate having irregularities, a repair error due to a decrease in the thickness of the lubricant can be prevented.

  When the magnetic disk of Example 3 is used, the same film formation process as that of the conventional magnetic disk can be used, so that a cheaper magnetic recording apparatus can be provided. However, since the uneven shape of the substrate is not completely reflected on the surface of the magnetic recording layer, performance such as recording density and reliability may be inferior. Therefore, which magnetic disk to select is determined based on the specifications of the product to be used.

  Hereinafter, materials used for each layer of the magnetic recording medium according to the embodiment of the present invention and a laminated structure of each layer will be described.

<Board>
As the substrate 11, for example, a glass substrate, an Al-based alloy substrate, a ceramic substrate, a carbon substrate, an Si single crystal substrate having an oxidized surface, and a substrate in which a NiP layer is formed on the surface of these substrates can be used. Amorphous glass or crystallized glass can be used for the glass substrate. Examples of the amorphous glass include soda lime glass and aluminosilicate glass. Examples of crystallized glass include lithium-based crystallized glass. As the ceramic substrate, a sintered body mainly composed of aluminum oxide, aluminum nitride, silicon nitride or the like, or a fiber reinforced one of these sintered bodies can be used. To form the NiP layer on the surface of the substrate, plating or sputtering is used.

<Soft magnetic underlayer>
The magnetic recording medium shown in FIG. 2 is a so-called perpendicular double-layer medium having a perpendicular magnetic recording layer on a soft magnetic underlayer (SUL). The soft magnetic underlayer of the perpendicular double-layer medium is provided to pass the recording magnetic field from the recording magnetic pole and to return the recording magnetic field to the return yoke disposed in the vicinity of the recording magnetic pole. That is, the soft magnetic underlayer plays a part of the function of the recording head and plays a role of improving the recording efficiency by applying a steep vertical magnetic field to the recording layer.

  For the soft magnetic underlayer, a high magnetic permeability material containing at least one of Fe, Ni, and Co is used. Such materials include FeCo alloys such as FeCo and FeCoV, FeNi alloys such as FeNi, FeNiMo, FeNiCr and FeNiSi, FeAl alloys and FeSi alloys such as FeAl, FeAlSi, FeAlSiCr, FeAlSiTiRu, FeAlO, and FeTa alloys such as Examples thereof include FeZr alloys such as FeTa, FeTaC, and FeTaN, such as FeZrN.

  For the soft magnetic underlayer, a material having a fine crystal structure such as FeAlO, FeMgO, FeTaN, FeZrN or the like containing Fe at 60 at% or more or a granular structure in which fine crystal particles are dispersed in a matrix can be used.

  As another material of the soft magnetic underlayer, a Co alloy containing Co and at least one of Zr, Hf, Nb, Ta, Ti, and Y can be used. Co is preferably contained at 80 at% or more. When such a Co alloy is formed by sputtering, an amorphous layer is easily formed. Amorphous soft magnetic materials do not have magnetocrystalline anisotropy, crystal defects, and grain boundaries, and thus exhibit very excellent soft magnetism. Further, by using an amorphous soft magnetic material, it is possible to reduce the noise of the medium. Suitable examples of the amorphous soft magnetic material include CoZr, CoZrNb, and CoZrTa-based alloys.

  An underlayer may be further provided under the soft magnetic underlayer in order to improve the crystallinity of the soft magnetic underlayer or the adhesion to the substrate. As the underlayer material, Ti, Ta, W, Cr, Pt, alloys containing these, or oxides or nitrides thereof can be used.

  An intermediate layer made of a non-magnetic material may be provided between the soft magnetic underlayer and the perpendicular magnetic recording layer. The role of the intermediate layer is to block the exchange coupling interaction between the soft magnetic underlayer and the recording layer and to control the crystallinity of the recording layer. As the intermediate layer material, Ru, Pt, Pd, W, Ti, Ta, Cr, Si, an alloy containing these, or an oxide or nitride thereof can be used.

  In order to prevent spike noise, the soft magnetic underlayer may be divided into a plurality of layers and antiferromagnetically coupled by sandwiching Ru having a thickness of 0.5 to 1.5 nm. Alternatively, the soft magnetic layer and a pinning layer made of a hard magnetic film having in-plane anisotropy such as CoCrPt, SmCo, or FePt or an antiferromagnetic material such as IrMn or PtMn may be exchange-coupled. In this case, in order to control the exchange coupling force, a magnetic layer such as Co or a nonmagnetic layer such as Pt may be laminated on the upper and lower sides of the Ru layer.

<Perpendicular magnetic recording layer>
For the perpendicular magnetic recording layer, for example, a material containing Co as a main component, containing at least Pt, optionally containing Cr, and further containing an oxide (for example, silicon oxide or titanium oxide) is used. In the perpendicular magnetic recording layer, the magnetic crystal grains preferably have a columnar structure. In the perpendicular magnetic recording layer having such a structure, the orientation and crystallinity of the magnetic crystal grains are good, and as a result, a signal / noise ratio (S / N ratio) suitable for high-density recording can be obtained. In order to obtain the above structure, the amount of oxide is important. The content of the oxide is preferably 3 mol% or more and 12 mol% or less, and more preferably 5 mol% or more and 10 mol% or less with respect to the total amount of Co, Pt, and Cr. When the content of the oxide in the perpendicular magnetic recording layer is in the above range, the oxide is precipitated around the magnetic particles, and the magnetic particles can be isolated and refined. When the content of the oxide exceeds the above range, the oxide remains in the magnetic particles, the orientation and crystallinity of the magnetic particles are impaired, and further, oxides are deposited above and below the magnetic particles. As a result, the magnetic particles However, a columnar structure penetrating the perpendicular magnetic recording layer vertically is not formed. On the other hand, when the oxide content is less than the above range, isolation and miniaturization of the magnetic particles are insufficient, resulting in an increase in noise during recording and reproduction, and a signal / noise ratio suitable for high density recording ( (S / N ratio) cannot be obtained.

  The Pt content in the perpendicular magnetic recording layer is preferably 10 at% or more and 25 at% or less. When the Pt content is in the above range, the uniaxial magnetic anisotropy constant Ku necessary for the perpendicular magnetic recording layer can be obtained, and the crystallinity and orientation of the magnetic particles are improved, which is suitable for high density recording as a result. Thermal fluctuation characteristics and recording / reproduction characteristics can be obtained. When the Pt content exceeds the above range, a layer having an fcc structure is formed in the magnetic particles, and the crystallinity and orientation may be impaired. On the other hand, if the Pt content is less than the above range, Ku suitable for high density recording, and hence thermal fluctuation characteristics, cannot be obtained.

  The Cr content in the perpendicular magnetic recording layer is preferably 0 at% or more and 16 at% or less, and more preferably 10 at% or more and 14 at% or less. When the Cr content is in the above range, high magnetization can be maintained without lowering the uniaxial magnetic anisotropy constant Ku of the magnetic particles, and as a result, recording / reproducing characteristics suitable for high-density recording and sufficient thermal fluctuation characteristics can be obtained. . When the Cr content exceeds the above range, the Ku of the magnetic particles is reduced, so that the thermal fluctuation characteristics are deteriorated, and the crystallinity and orientation of the magnetic particles are deteriorated. As a result, the recording / reproducing characteristics are deteriorated.

  The perpendicular magnetic recording layer contains one or more additive elements selected from B, Ta, Mo, Cu, Nd, W, Nb, Sm, Tb, Ru, and Re in addition to Co, Pt, Cr, and oxide. You may go out. By including these additive elements, it is possible to promote miniaturization of magnetic particles or improve crystallinity and orientation, and to obtain recording / reproduction characteristics and thermal fluctuation characteristics suitable for higher density recording. it can. The total content of these additive elements is preferably 8 at% or less. If it exceeds 8 at%, phases other than the hcp phase are formed in the magnetic particles, so that the crystallinity and orientation of the magnetic particles are disturbed, resulting in recording / reproduction characteristics and thermal fluctuation characteristics suitable for high-density recording. It becomes impossible.

  Other materials for the perpendicular magnetic recording layer include CoPt alloys, CoCr alloys, CoPtCr alloys, CoPtO, CoPtCrO, CoPtSi, and CoPtCrSi. For the perpendicular magnetic recording layer, a multilayer film of Co and an alloy mainly composed of at least one selected from the group consisting of Pt, Pd, Rh, and Ru can be used. In addition, a multilayer film such as CoCr / PtCr, CoB / PdB, or CoO / RhO to which Cr, B, or O is added can be used for each layer of these multilayer films.

  The thickness of the perpendicular magnetic recording layer is preferably 5 to 60 nm, and more preferably 10 to 40 nm. A perpendicular magnetic recording layer having a thickness in this range is suitable for high recording density. If the thickness of the perpendicular magnetic recording layer is less than 5 nm, the reproduction output tends to be too low and the noise component tends to be higher. On the other hand, if the thickness of the perpendicular magnetic recording layer exceeds 40 nm, the reproduction output tends to be too high and the waveform tends to be distorted. The coercive force of the perpendicular magnetic recording layer is preferably 237000 A / m (3000 Oe) or more. When the coercive force is less than 237000 A / m (3000 Oe), the thermal fluctuation resistance tends to be inferior. The perpendicular squareness ratio of the perpendicular magnetic recording layer is preferably 0.8 or more. When the vertical squareness ratio is less than 0.8, the thermal fluctuation resistance tends to be poor.

<Protective layer>
The protective layer functions to prevent corrosion of the perpendicular magnetic recording layer and to prevent damage to the medium surface when the magnetic head comes into contact with the medium. Examples of the material for the protective layer include materials containing C, SiO ₂ , and ZrO ₂ . The thickness of the protective layer is preferably 1 to 10 nm. When the thickness of the protective layer is in the above range, the distance between the head and the medium can be reduced, which is suitable for high density recording.

<Lubrication layer>
As the lubricant, for example, perfluoropolyether, fluorinated alcohol, fluorinated carboxylic acid and the like can be used.

1 is a perspective view of a magnetic recording apparatus according to Embodiment 1. FIG. FIG. 3 is a cross-sectional view of a magnetic disk used in the magnetic recording apparatus according to the first embodiment. FIG. 3 is a plan view schematically showing the surface of the magnetic disk of FIG. 2. FIG. 4 is a plan view showing a servo area and a data area of the magnetic disk of FIG. 3 in more detail. FIG. 5 is a plan view showing the servo area of the magnetic disk of FIG. 4 in more detail. FIG. 3 is a plan view showing an ABS surface of a head slider used in the magnetic recording apparatus according to the first embodiment. FIG. 3 is a diagram schematically illustrating a region where pressure is generated by a pad and a flow of lubricant in a servo region of a magnetic disk used in the magnetic recording apparatus according to the first embodiment. FIG. 4 is a diagram illustrating a relationship between a value of L / s and a repair error rate of the magnetic recording apparatus in the first embodiment. FIG. 6 is a cross-sectional view showing a part of a magnetic disk used in the magnetic recording apparatus in Example 2. The figure which shows typically the relationship between the surface roughness of a magnetic disc, and uneven | corrugated difference t. FIG. 10 is a diagram showing the relationship between the unevenness difference of the magnetic disk, the design flying height of the head slider, and the repair error rate for the magnetic recording device manufactured in Example 2. FIG. 6 is a cross-sectional view of an example of a magnetic recording medium used in the magnetic recording apparatus of Example 3. FIG. 6 is a cross-sectional view of another example of a magnetic recording medium used in the magnetic recording apparatus of Example 3.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 11 ... Disk substrate, 12 ... Underlayer, 13 ... Recording layer, 14 ... Protective layer, 15 ... Lubrication layer, 16 ... Nonmagnetic layer, 21 ... Recording track area, 22 ... Servo area, 23 ... Data area, 45 ... Tray Ring pad, 31 ... address area, 32 ... burst area, 35 ... area generating one unit of burst signal, 45 ... trailing pad, 70 ... housing, 71 ... magnetic disk, 72 ... spindle motor, 73 ... pivot, 74 ... Actuator arm, 75 ... Suspension, 76 ... Head slider, 77 ... Voice coil motor (VCM), 80 ... Magnetic head.

Claims (4)

A data area including a substrate, a magnetic layer formed on the substrate, and a lubricant applied to the surface, and including a pattern of the magnetic layer forming a recording track in the plane of the magnetic layer, as a servo signal Rotating, including a servo region of length s formed between data regions along the track length direction, including the pattern of the magnetic layer utilized, and a non-magnetic layer separating these magnetic layer patterns A magnetic recording medium;
A head slider provided with a magnetic head, which is attached to a suspension attached to an actuator arm and supported in a floating state on the magnetic recording medium, and is closest to the magnetic recording medium when flying on the medium facing surface. A head slider in which a length L in the slider slider traveling direction is equal to or less than a length s of the servo area;
A magnetic recording apparatus comprising: an actuator for moving the actuator arm in a radial direction of the magnetic recording medium.   The magnetic recording apparatus according to claim 1, wherein a difference in height between the magnetic layer and the nonmagnetic layer of the magnetic recording medium is 20 nm or less.   The magnetic recording apparatus according to claim 2, wherein a difference in height between the magnetic layer and the nonmagnetic layer of the magnetic recording medium is 5 nm or less.   The magnetic recording apparatus according to claim 1, wherein the substrate of the magnetic recording medium has irregularities of 1 nm or more on a surface thereof.

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