JP2012043490A - Method for manufacturing magnetic recording medium - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for manufacturing a magnetic recording medium which significantly increases the total number of transferring with one master information carrier.SOLUTION: A method for manufacturing a magnetic recording medium W includes the steps of: magnetically transferring, after a master information carrier M having a transfer pattern corresponding to an information signal is laminated on a magnetic recording medium W having at least a magnetic layer formed on a non-magnetic substrate, the information signal from the master information carrier M to the magnetic recording medium W while applying an external magnetic field to the magnetic recording medium W from a side of the master information carrier M; and wiping a surface of the magnetic recording medium with a wiping tape having micro beads fixed on a surface of the substrate before the lamination of the master information carrier M on the magnetic recording medium W, while the master information carrier M allowed for repeating a magnetic transfer is used.

Description

  The present invention relates to a method for manufacturing a magnetic recording medium used in a hard disk device (HDD) or the like.

  HDD (Hard Disk Drive), which is a kind of magnetic recording / reproducing device, is currently increasing in recording density by 1.5 times or more per year, and it is said that this trend will continue in the future. Accordingly, development of a magnetic head and a magnetic recording medium suitable for increasing the recording density has been advanced. In the latest magnetic recording apparatus, the track density is 320 kTPI or more.

  For this reason, in a magnetic recording medium having a high track density, the tracking servo technology of the magnetic head plays an important role in order to accurately scan the magnetic head on the track. Specifically, in current hard disk drives, tracking servo signals, information signals such as address information signals and reproduction clock signals (hereinafter referred to as servo signals, etc.) are recorded at regular angular intervals during one round of the disk. Has been. Control is performed to correct the position of the magnetic head so that the magnetic head accurately scans the track while detecting the position of the magnetic head based on these signals reproduced from the magnetic head at regular intervals. ing.

  Therefore, the servo signal and the like described above serve as a reference signal for the magnetic head to accurately scan the track, and high positioning accuracy is required for writing these signals. For this reason, in a conventional hard disk drive manufacturing site, a servo signal recording device (hereinafter referred to as a servo writer) incorporating a high-precision position detection device is used to write a servo signal or the like to a magnetic recording medium. It has been broken. Further, the servo writer has a structure in which a large number of magnetic recording media are chucked on one spindle and servo signals and the like are simultaneously written on these magnetic recording media in order to increase productivity.

  However, the writing of servo signals and the like by the servo writer described above has the following problems. That is, it takes a lot of time to write signals over a large number of tracks while positioning the magnetic head with high accuracy, and in order to further increase the productivity, it is necessary to operate many servo writers simultaneously. . However, if the number of servo writers to be introduced is increased, a large amount of cost is required for maintenance. Further, if the number of magnetic recording media that can be chucked at the same time is increased by extending the spindle, blurring is likely to occur during rotation, leading to a decrease in writing accuracy on the magnetic recording medium. Therefore, the number of magnetic recording media that can be chucked on one spindle is naturally limited. These problems become more serious as the track density of the magnetic recording medium improves and the number of tracks increases.

  Therefore, writing the servo signal, etc. to the magnetic recording medium is not performed by a servo writer, but using a master information carrier on which a magnetic transfer pattern corresponding to all servo signals, etc. is written, the signal written on the master information carrier is A method has been proposed in which magnetic transfer is performed collectively on a magnetic recording medium (see, for example, Patent Document 1).

  Specifically, in this method, a signal written on the master information carrier is magnetically transferred to the magnetic recording medium while applying a magnetic field as energy for transfer from the outside while the master information carrier and the magnetic recording medium are in close contact with each other. To do. As a result, it is possible to perform a writing operation such as a servo signal on the magnetic recording medium in a short time. Such a master information carrier can be used repeatedly.

JP 10-40544 A JP 2001-6169 A JP 2000-203889 A

  By the way, when performing the magnetic transfer described above, if there are abnormal projections or the like on the surface of the magnetic recording medium, when the magnetic recording medium and the master information carrier are overlapped, the magnetic recording medium or A problem arises in that a concave portion occurs on the surface of the master information carrier, resulting in incomplete magnetic transfer.

  Since the master information carrier used for magnetic transfer is very expensive, in order to reduce the manufacturing cost of the magnetic recording medium, the total number of times that one master information carrier can be transferred before it is damaged due to wear or the like ( It is important to increase the number of times of use.

  Therefore, the master information is obtained by subjecting the surface of the magnetic recording medium to burnishing and wiping, removing protrusions and dust on the surface, and then superimposing the master information carrier on the magnetic recording medium to perform magnetic transfer. It has been proposed to increase the number of times the carrier is used (see, for example, Patent Document 2).

  However, according to the study by the present inventors, when the contaminants adhering to the surface of the magnetic recording medium described above are removed by wiping, lint falls off the wiping tape and adheres to the surface of the magnetic recording medium. It was revealed that a situation in which magnetic transfer was incomplete occurred.

  In this case, a situation in which the transfer pattern becomes incomplete before the master information carrier is damaged due to wear occurs, so that the total number of times that can be repeatedly transferred by one master information carrier is applied to commercial production. It is very difficult to increase the number of use to a sufficient number.

  The present invention has been proposed in view of such conventional circumstances. When magnetic transfer is performed using a master information carrier that can be repeatedly used, the total number of times that can be repeatedly transferred by one master information carrier. It is an object of the present invention to provide a method for manufacturing a magnetic recording medium in which the quality is greatly improved.

  As a result of intensive studies to solve the above problems, the present inventors have found that the magnetic transfer pattern by the master information carrier is incomplete when the contaminants adhering to the surface of the magnetic recording medium are removed by wiping. In addition, it was clarified that dust such as lint that fell off the wiping tape and adhered to the surface of the magnetic recording medium was the cause.

  Therefore, the inventors wipe the surface of the magnetic recording medium using a wiping tape in which microbeads are fixed to the surface of the support before magnetic transfer to the magnetic recording medium using the master information carrier. By providing the wiping step, it was found that contaminants attached to the surface of the magnetic recording medium can be appropriately removed while preventing the generation of dust such as the above-mentioned lint, and the present invention has been completed.

That is, the present invention provides the following means.
(1) After superimposing a magnetic recording medium having at least a magnetic layer on a nonmagnetic substrate and a master information carrier on which a transfer pattern corresponding to an information signal is formed, an external magnetic field is applied from the master information carrier side. A magnetic recording medium manufacturing method including a wiping step of magnetically transferring an information signal from the master information carrier to the magnetic recording medium while applying
Using a master information carrier that can be repeatedly used when performing the magnetic transfer, and before superimposing the master information carrier and the magnetic recording medium, using a wiping tape having microbeads fixed to the surface of the support, A method of manufacturing a magnetic recording medium, comprising a step of wiping the surface of the magnetic recording medium.
(2) The method for producing a magnetic recording medium according to (1), wherein a lubricant is applied to the wiping tape.
(3) The above-mentioned wiping tape, wherein a microbead made of an acrylic resin having an average particle diameter of 2 to 3 μm is fixed to the surface of a support made of a resin film with a binder. A method for producing a magnetic recording medium according to 1) or (2).
(4) Before the wiping step, another wiping step of wiping the surface of the magnetic recording medium using a cloth wiping tape, and a burnish tape in which abrasive grains are fixed to the surface of the support are used. The method for producing a magnetic recording medium according to any one of (1) to (3), wherein a burnishing step for polishing the surface of the magnetic recording medium is provided.

  As described above, in the present invention, before performing magnetic transfer to the magnetic recording medium using the master information carrier, the surface of the magnetic recording medium is wiped using the wiping tape having the microbeads fixed to the surface of the support. By doing so, it is possible to appropriately remove contaminants attached to the surface of the magnetic recording medium while suppressing the generation of dust from the wiping tape.

  Therefore, according to the present invention, when the master information carrier and the magnetic recording medium are superimposed, it is possible to prevent contaminants attached to the surface of the magnetic recording medium W from being transferred to the master information carrier. When magnetic transfer is performed using a usable master information carrier, the total number of times that can be repeatedly transferred by one master information carrier can be dramatically increased.

FIG. 1 is a cross-sectional view showing an example of a wiping tape used in the wiping process of the present invention. FIG. 1 is a configuration diagram showing an example of a wiping device used in the wiping process of the present invention. FIG. 3 is a cross-sectional view for explaining the magnetic transfer process of the present invention. FIG. 4 is a cross-sectional view showing an example of a magnetic recording medium. FIG. 5 is a perspective view showing an example of a magnetic recording / reproducing apparatus.

  Hereinafter, a method for manufacturing a magnetic recording medium to which the present invention is applied will be described in detail with reference to the drawings. In the drawings used in the following description, in order to make the features easy to understand, the portions that become the features may be schematically shown for convenience, and the dimensional ratios of the portions are not always the same as the actual ones.

  In the method of manufacturing a magnetic recording medium to which the present invention is applied, a magnetic recording medium having at least a magnetic layer formed on a nonmagnetic substrate and a master information carrier on which a transfer pattern corresponding to an information signal is formed are superimposed. And a magnetic transfer step of magnetically transferring an information signal from the master information carrier to the magnetic recording medium while applying an external magnetic field from the master information carrier side, and can be used repeatedly when performing magnetic transfer. In addition to using an information carrier, a wiping step for wiping the surface of the magnetic recording medium using a wiping tape having microbeads fixed to the surface of the support is provided before the magnetic transfer step. is there.

(Wiping process using microbeads)
Specifically, in the wiping process using the microbeads of the present invention, for example, a wiping tape 1 as shown in FIG. 1 is used. The wiping tape 1 includes a support 2 in the form of a tape, and a bead layer 5 to which a number of microbeads 3 are fixed via a binder 4 so as to cover one surface of the support 2. Yes.

  As the support 2, for example, a flexible resin film such as polyethylene terephthalate can be used. As the microbeads 3, those made of an acrylic resin can be suitably used, and among these, acrylic beads having an average particle diameter of 2 to 3 μm are preferably used.

  The binder 4 is not particularly limited as long as it can support the microbeads 3 on the surface of the support 2. For example, a thermosetting resin, a thermoplastic resin, a photosensitive resin, or the like can be used. Specifically, examples of the thermosetting resin include urea resin, melamine resin, phenol resin, epoxy resin, unsaturated polyester resin, alkyd resin, and urethane resin. Examples of the thermoplastic resin include acrylonitrile butadiene styrene (ABS) resin, butadiene styrene resin, polybutadiene resin, and acrylic rubber-based MBS resin. Examples of the photosensitive resin include methacrylic resin, phenol resin, urea resin, melamine resin, polystyrene resin, polyacetal resin, polycarbonate resin, and epoxy resin. Furthermore, one kind of these resins may be used alone, or two or more kinds may be used in combination.

  Then, in the wiping process using the microbeads of the present invention, the wiping tape 1 is used to rotate the disk-shaped magnetic recording medium, and the microbeads 3 of the wiping tape 1 are placed on the surface of the magnetic recording medium. This is performed by pressing a surface (hereinafter referred to as a wiping surface) S provided with the. Thereby, while preventing the generation of dust such as lint, the contaminants attached to the surface of the magnetic recording medium are wiped off, and the surface of the magnetic recording medium is cleaned.

  Specifically, in the wiping process using the microbeads of the present invention, for example, a wiping device 20 as shown in FIG. 2 can be used. As shown in FIG. 2A, the wiping device 20 includes a medium rotation drive mechanism 21 that rotationally drives the magnetic recording medium W, a tape traveling mechanism 22 that travels the wiping tape 1, and a surface of the magnetic recording medium W. And a tape pressing mechanism 23 for pressing the wiping tape 1 against the tape. Further, the wiping device 20 includes a tape traveling mechanism 22 and a tape pressing mechanism 23 on both sides of the magnetic recording medium W in order to simultaneously process both surfaces of the magnetic recording medium W by the wiping tape 1. It has become.

  The medium rotation drive mechanism 21 has a spindle 24 that is rotationally driven by a motor (not shown), and a chuck portion 25 that holds the central portion of the magnetic recording medium W at the tip of the spindle 24. The magnetic recording medium W that is detachably attached to the tip of the spindle 24 is rotated.

  The tape traveling mechanism 22 is a wiping tape 1 disposed so that the wiping surface S faces the main surface of the magnetic recording medium W on both sides of the magnetic recording medium W rotated by the medium rotation driving mechanism 21. Is moved in a direction Ra, Rb opposite to the rotation direction r of the magnetic recording medium W.

  More specifically, the tape running mechanism 22 is configured such that a supply reel and a take-up reel (not shown) and a wiping tape 1 supplied from the supply reel are wound between the supply reel and the take-up reel while being taken up by the take-up reel. A plurality of guide rolls 26a to 26d for guiding the wiping tape 1 therebetween. The wiping tape 1 is parallel to the main surface of the magnetic recording medium W between the guide rolls 26a and 26b, and the main surface of the magnetic recording medium W is between the guide rolls 26b and 26c. And is guided by guide rolls 26a to 26d arranged at respective positions so that the guide rolls 26c and 26d are again parallel to the main surface of the magnetic recording medium W. It is supposed to run. The plurality of guide rolls 26a to 26d are respectively disposed at symmetrical positions with the magnetic recording medium W interposed therebetween.

  The tape pressing mechanism 23 presses the wiping surface 1 of the wiping tape 1 on the magnetic recording medium W while pressing the wiping tape 1 facing the magnetic recording medium W from the surface (back surface) opposite to the wiping surface S. It presses (contacts) the surface. Specifically, the tape pressing mechanism 23 includes a pressing pad 27 between the wiping tape 1 traveling between the guide rolls 26a and 26b and the wiping tape 1 traveling between the guide rolls 26c and 26d. Has a swing arm 28 attached thereto. Further, the swing arm 28 can swing in a direction in which the swing arm 28 can come into contact with and separate from the back surface of the wiping tape 1 on the side facing the magnetic recording medium W by a drive mechanism (not shown). Further, the swing arms 28 to which such pressing pads 27 are attached are respectively arranged at symmetrical positions with respect to the magnetic recording medium W.

  The pressing pad 27 is preferably made of a flexible resin, woven fabric, or the like. Further, instead of such a pressing pad 27, a configuration may be adopted in which a pressing roller made of rubber or the like is attached to the swing arm 28.

  In the wiping process of the present invention using the wiping device 20 having the above-described structure, as shown in FIG. 2B, the back surface of the wiping tape 1 running between the guide rolls 26a and 26b is swung. When the arm 28 is pressed through the pressing pad 27, the wiping tape 1 is pushed out from between the guide rolls 26a and 26b in the direction approaching the magnetic recording medium W, and the wiping surface S of the wiping tape 1 is pressed. Is pressed against the surface of the magnetic recording medium W rotated by the medium rotating mechanism 21. As a result, contaminants and the like adhering to the surface of the magnetic recording medium W are wiped away by the wiping tape 1 and the surface of the magnetic recording medium W is cleaned.

  Here, in the wiping step using the microbeads of the present invention, when the surface of the magnetic recording medium W is wiped by using the wiping tape 1 in which the microbeads 3 are fixed to the surface of the support 2 described above, It is possible to appropriately remove contaminants attached to the surface of the magnetic recording medium W while preventing the generation of dust such as lint from the wiping tape 1.

  As the wiping surface S of the wiping tape 1, as shown in FIG. 1, for example, a material coated with a lubricant 6 such as perfluoropolyether, fluorinated alcohol, or fluorinated carboxylic acid can be used. It is.

  In this case, the contaminant transferred from the surface of the magnetic recording medium W to the wiping tape 1 can be reliably held on the wiping surface S of the wiping tape 1. Further, the lubricant 6 can reduce the dynamic frictional resistance of the wiping tape 1 to the surface of the magnetic recording medium W. As the lubricant 6, the same lubricant that is generally used as the lubricant applied to the surface of the magnetic recording medium W can be used, so that the lubricant 6 is applied from the wiping tape 1 to the surface of the magnetic recording medium W. Even if it is transferred, there is no particular effect. Further, the wiping step using the microbeads of the present invention is preferably performed before the lubricant is applied to the surface of the magnetic recording medium W.

  In addition, before the wiping step using the microbeads of the present invention, another wiping step of wiping the surface of the magnetic recording medium using a cloth wiping tape and the abrasive grains were fixed to the surface of the support. It is preferable to provide a burnishing step for polishing the surface of the magnetic recording medium using a burnish tape.

  That is, although the wiping tape using the microbeads of the present invention generates less dust than the cloth wiping tape, the dust capturing ability is not so high, and abnormal projections formed on the surface of the magnetic recording medium are not generated. Since the effect of polishing removal is low, in addition to the wiping step using the microbeads of the present invention, by using a wiping step using a cloth wiping tape and a burnishing step using a burnish tape, It is possible to make the surface of the magnetic recording medium have a higher level of cleanliness, and to dramatically increase the number of transfers in the subsequent magnetic transfer process.

(Wiping process using cloth wiping tape)
The wiping process using the cloth wiping tape used in the present invention can be performed using the same apparatus as the wiping process using the microbeads. That is, this wiping step is a step of lightly wiping the surface of the medium by pressing the surface of the wiping tape against the surface of the medium with a rubber contact roll or pad while running the cloth wiping tape relative to the surface of the medium. is there. By performing such a wiping process, sputter dust and the like on the surface of the medium is removed, so that the flying height of the magnetic head can be further reduced.

  Here, as the wiping tape made of cloth, a wiping tape obtained by slitting a cloth made of super fine fibers into a belt shape, a woven or knitted fabric of super fine fiber multifilament yarn, or the like is used.

  Further, the wiping method of the magnetic recording medium using such a wiping tape is specifically the surface of the wiping tape (wiping surface) on the surface of the magnetic recording medium while rotating the magnetic recording medium. This is done by pressing. Thereby, sputter dust etc. on the surface of the magnetic recording medium are wiped off, and the surface is cleaned. Here, the wiping tape is stretched between the supply reel and the take-up reel, is sequentially supplied from the supply reel, and is sequentially taken up by the take-up reel. In the middle of running from the supply reel side to the take-up reel side, the surface (back surface) opposite to the wiping surface of the wiping tape is pressed by a backing roll such as rubber or felt, and the wiping surface is magnetically recorded. Pressed against the surface of the medium.

(Vernish process)
The burnish process used in the present invention can be performed using the same apparatus as the wiping process using the microbeads. That is, this burnishing process is performed using a polishing tape or the like coated with alumina abrasive grains, and the medium surface is lightly polished by pressing the polishing tape against the medium surface with a rubber contact roll. . By performing such processing, abnormal projections and the like on the medium surface are removed.

  As the burnish tape used in the burnish process, a tape formed by forming an abrasive layer in which abrasive grains are usually fixed on the surface of a polyester base film (support) can be used. The abrasive layer has an average particle size of about 0.05 μm to 50 μm, chromium oxide, α-alumina, silicon carbide, nonmagnetic iron oxide, diamond, γ-alumina, α, γ-alumina, fused alumina, corundum, Abrasive grains such as artificial diamond are used. Then, by sliding this burnish tape in contact with the magnetic layer side surface of the magnetic recording medium, fine dust adhering to the surface of the magnetic recording medium is removed and abnormal projections existing on the surface are removed. Etc. are polished and removed to smooth the surface.

(Magnetic transfer process)
In the magnetic transfer process, writing of servo signals and the like is performed by magnetic transfer on the magnetic recording medium W whose surface has been cleaned by the wiping process using the microbeads of the present invention. Specifically, in this magnetic transfer process, first, the signal recording surface of the magnetic recording medium W is initially magnetized. This initial magnetization is performed by applying an initial DC magnetic field in one direction in the track direction in the case of the in-plane magnetic recording medium W, and in the direction perpendicular to the medium surface in the case of the perpendicular magnetic recording medium W. This is done by applying an initial DC magnetic field in the direction.

  This initial DC magnetic field can be applied using a permanent magnet or an electromagnet. As the permanent magnet, it is preferable to use an NdFeB-based sintered magnet that is more stable and has a strong magnetic force. In addition, it is preferable to apply the initial DC magnetic field in a non-contact state with the magnetic recording medium W in order to maintain the cleanliness of the surface of the magnetic recording medium W.

  Next, as shown in FIG. 3, the signal recording surface of the magnetic recording medium W after application of the initial DC magnetic field, and the transfer surface of the master information carrier M on which a transfer pattern corresponding to a servo signal or the like is formed, Are brought into close contact with each other with a predetermined pressing force. In this state, an external magnetic field for transfer is applied from the opposite side of the transfer surface of the master information carrier M using the magnetic field generating means G while moving the magnetic field generating means G relatively in the track direction X. To do. This external magnetic field for transfer is a magnetic field in the opposite direction to the initial DC magnetic field. Thereby, in the magnetic recording medium W, magnetization reversal occurs at a position facing the transfer pattern of the master information carrier M, and a magnetization pattern corresponding to a servo signal or the like is written by magnetic transfer.

  The master information carrier M can be manufactured by a known method. Specifically, when manufacturing such a master information carrier M, first, an electron beam resist is applied to the surface of a silicon wafer by spin coating. Thereafter, this resist is irradiated with an electron beam modulated in accordance with a servo signal or the like using an electron beam exposure apparatus, and after exposing and developing the resist, silicon is removed by removing unexposed portions. A resist pattern corresponding to the transfer pattern is formed on the wafer. In addition to the servo signal of the hard disk drive, examples of the transfer pattern include a pre-servo signal and a self-servo signal for generating a servo signal in the hard disk drive.

  Next, using this resist pattern as a mask, a reactive etching process is performed on the silicon wafer, and a portion not masked with the resist is dug down. After this etching process, the resist remaining on the silicon wafer is removed by washing with a solvent. Thereafter, the silicon wafer is dried to obtain a master for producing a master information carrier.

  Next, a conductive layer made of Ni is formed on the master with a thickness of about 10 nm by sputtering. Thereafter, a Ni layer having a thickness of several microns is formed on the master by electroforming using the master on which the conductive layer is formed. Thereafter, the Ni layer is removed from the master, and the Ni layer is washed, etc., to obtain the Ni base material 100 having the convex portions 100a and the concave portions 100b formed on the surface.

  Next, the magnetic layer 101 is formed on the surface of the Ni substrate 100. As the magnetic layer 101, the same magnetic layer used in the magnetic recording medium W can be used. Of the magnetic layer 101 formed on the surface of the Ni base material 100, the portion of the magnetic layer 101 where the convex portion 100a is formed is used for magnetic transfer to the magnetic recording medium W, and the concave portion 100a is formed. The portion of the magnetic layer 101 thus formed is not used for magnetic transfer because it does not contact the magnetic recording medium W.

Further, a protective film (not shown) is formed on the surface of the Ni base 100 similarly to the magnetic recording medium W. This protective film is for enhancing the wear resistance of the master information carrier M, and a hard carbon film having a thickness of about several nm is used.
Through the above steps, a master information carrier M on which a transfer pattern corresponding to a servo signal or the like is formed can be obtained.

  The magnetic field generating means G is composed of an electromagnet or a permanent magnet. In the case of an in-plane magnetic recording medium, an external magnetic field for transfer is generated in the other direction of the track, and in the case of a perpendicular magnetic recording medium, An external magnetic field for transfer is generated in the other direction perpendicular to the medium surface. The magnetic field generating means G can be rotated in the track direction X to the center of the magnetic recording medium W while generating an external magnetic field in the same direction in the radial direction of the magnetic recording medium W.

  Here, the magnetic recording medium W built in the hard disk drive generally has a magnetic layer 201 formed on both surfaces of the non-magnetic substrate 200, and a single hard disk drive has a plurality of magnetic recording media. W is often built-in. For this reason, in a hard disk drive, a plurality of magnetic heads are integrally moved by a stack structure, but the track width of the magnetic recording medium W is becoming increasingly narrower, so that data is written on the signal recording surface of one magnetic recording medium W. It is difficult to position the magnetic head on another signal recording surface using the servo signal or the like because of the accuracy of the stack structure of the head.

  Therefore, in the magnetic transfer process of the present invention, it is preferable to write servo signals and the like on both surfaces of the magnetic recording medium W by magnetic transfer. Specifically, both surfaces of the magnetic recording medium W are sandwiched between a pair of master information carriers M. In this state, an external magnetic field for transfer is applied from the side opposite to the transfer surface of the master information carrier M using the magnetic field generating means G. Thereby, servo signals and the like can be written on both surfaces of the magnetic recording medium W.

  In addition, the coercive force Hc of the magnetic layer 201 is usually 320 kA / m (about 4000 Oe) or more. Therefore, in the magnetic transfer process of the present invention, after the magnetic layer 201 is initially DC magnetized, both sides of the magnetic recording medium are sandwiched between the master information carriers M, and a magnetic field having a magnetic transfer strength is applied via the master information carrier M. It is preferable to perform magnetic transfer.

  In the magnetic transfer process, the master information carrier M and the magnetic recording medium W are overlapped in order to perform magnetic transfer on the magnetic recording medium W whose surface is highly cleaned by the wiping process using the microbeads of the present invention. When they are combined, it is possible to prevent the metal corrosive matter or the like slightly remaining on the surface of the magnetic recording medium W from being transferred and accumulated little by little on the master information carrier M. In particular, it is possible to prevent such accumulated material from entering the concave portion 100b of the transfer surface of the master information carrier M and eroding the convex portion 100a while deteriorating the magnetization pattern written on the magnetic recording medium W. .

  Therefore, according to the present invention, it is possible to dramatically increase the total number of times that can be repeatedly transferred by one master information carrier M, and as a result, it is possible to greatly reduce the production cost of the magnetic recording medium. It is.

  After the magnetic transfer process, a glide inspection is performed on the obtained magnetic recording medium W. The glide inspection is a process for inspecting the surface of the magnetic recording medium W for any projections. That is, when recording / reproduction is performed on the magnetic recording medium W using the magnetic head, if there is a protrusion with a height higher than the flying height (space between the medium and the magnetic head) on the surface of the magnetic recording medium W, the magnetic head May cause damage to the magnetic head or defects in the magnetic recording medium W. In the glide inspection, the presence or absence of such high protrusions is inspected.

  Usually, a certification inspection is performed on the magnetic recording medium W that has passed the glide inspection. The certification inspection is similar to recording / reproduction of a normal hard disk drive, after a predetermined signal is recorded on the magnetic recording medium W by a magnetic head, the signal is reproduced, and the magnetic recording medium W is reproduced by the obtained reproduction signal. Is detected, and the quality of the medium, such as the electrical characteristics of the magnetic recording medium W and the presence or absence of defects, is confirmed.

  The magnetic recording medium W manufactured by applying the present invention is different from the conventional certification test because the servo signal and the like are already written therein. That is, in the magnetic recording medium W manufactured by applying the present invention, an inspection of a format in which the magnetic head is positioned at a specific position and read / write is performed using a servo signal or the like magnetically transferred to the magnetic recording medium W. Do.

(Magnetic recording medium)
Next, an example of the magnetic recording medium W manufactured by applying the present invention is shown in FIG.
As shown in FIG. 4, the magnetic recording medium W includes a soft magnetic underlayer 32 including two soft magnetic layers 32a antiferromagnetically coupled by a spacer layer 32b on a nonmagnetic substrate 31, and an orientation control layer. 33, a perpendicular magnetic layer 34, a protective layer 35, and a lubricant film 36 are sequentially stacked.

  The perpendicular magnetic layer 34 includes three layers of a lower magnetic layer 34a, an intermediate magnetic layer 34b, and an upper magnetic layer 34c, and a nonmagnetic layer 37a is provided between the magnetic layer 34a and the magnetic layer 34b. By sandwiching the nonmagnetic layer 37b between the magnetic layer 34b and the magnetic layer 34c, the magnetic layers 34a to 34c and the nonmagnetic layers 37a and 37b are alternately stacked.

  As the nonmagnetic substrate 31, for example, a metal substrate made of a metal material such as aluminum or an aluminum alloy may be used. For example, a nonmetal substrate made of a nonmetal material such as glass, ceramic, silicon, silicon carbide, or carbon. May be used. In addition, it is also possible to use a substrate in which a NiP layer or a NiP alloy layer is formed on the surface of the metal substrate or nonmetal substrate by using, for example, a plating method or a sputtering method.

  As the glass substrate, for example, amorphous glass or crystallized glass can be used, and as the amorphous glass, for example, general-purpose soda lime glass or aluminosilicate glass can be used. In addition, as the crystallized glass, for example, lithium-based crystallized glass can be used. As the ceramic substrate, for example, general-purpose aluminum oxide, a sintered body mainly composed of aluminum nitride, silicon nitride, or the like, or a fiber reinforced material thereof can be used.

  The nonmagnetic substrate 31 has an average surface roughness (Ra) of 1 nm (10 mm) or less, preferably 0.5 nm or less, from the viewpoint of suitable for high recording density recording with a magnetic head flying low. preferable. Further, it is preferable that the surface fine waviness (Wa) is 0.3 nm or less (more preferably 0.25 nm or less) from the viewpoint of being suitable for high recording density recording with the magnetic head flying low. In addition, it is possible to use a magnetic head having a chamfered portion at the end face and a surface average roughness (Ra) of at least one of the side surface portion of 10 nm or less (more preferably 9.5 nm or less). Preferred for stability. In addition, microwaviness (Wa) can be measured as surface average roughness in a measuring range of 80 μm, for example, using a surface roughness measuring device P-12 (manufactured by KLM-Tencor).

  Further, since the nonmagnetic substrate 31 is in contact with the soft magnetic underlayer 32 containing Co or Fe as a main component, there is a possibility that corrosion proceeds due to the influence of surface adsorption gas, moisture, diffusion of substrate components, and the like. is there. In this case, it is preferable to provide an adhesion layer between the non-magnetic substrate 31 and the soft magnetic underlayer 32, which makes it possible to suppress them. In addition, as a material of the adhesion layer, for example, Cr, Cr alloy, Ti, Ti alloy, or the like can be selected as appropriate. The thickness of the adhesion layer is preferably 2 nm (20 mm) or more.

  As the soft magnetic layer 32a, a material containing Fe: Co in the range of 40:60 to 70:30 (atomic ratio) is preferably used. Moreover, in order to improve the magnetic permeability and corrosion resistance, it is preferable to contain any one selected from Ta, Nb, Zr, and Cr in the range of 1 to 8 atomic%. As the spacer layer 32b, Ru, Re, Cu, or the like can be used. Among these, it is particularly preferable to use Ru.

  The orientation control layer 33 is for improving the recording / reproducing characteristics by refining the crystal grains of the perpendicular magnetic layer 34. The orientation control layer 33 is not particularly limited, but a layer having an hcp structure, an fcc structure, or an amorphous structure is preferably used. In particular, it is preferable to use a Ru alloy, a Ni alloy, a Co alloy, a Pt alloy, or a Cu alloy. Further, these alloys may be multilayered. For example, it is preferable to adopt a multilayer structure of Ni-based alloy and Ru-based alloy, a multilayer structure of Co-based alloy and Ru-based alloy, or a multilayer structure of Pt-based alloy and Ru-based alloy from the substrate side.

  Here, in the initial part of the perpendicular magnetic layer 34 immediately above the orientation control layer 33, disorder of crystal growth is likely to occur, which causes noise. In this case, it is preferable to provide a nonmagnetic underlayer 38 between the orientation control layer 33 and the perpendicular magnetic layer 34. The occurrence of noise can be suppressed by replacing the disturbed portion of the initial portion with the nonmagnetic underlayer 38.

As the nonmagnetic underlayer 38, it is preferable to use a layer made of a material containing Co as a main component and further containing an oxide. The Cr content is preferably 25 atomic% or more and 50 atomic% or less. As the oxide, for example, oxides such as Cr, Si, Ta, Al, Ti, Mg, and Co are preferably used, and among them, TiO ₂ , Cr ₂ O ₃ , SiO _{2, and the} like are preferably used. it can. The content of the oxide is preferably 3 mol% or more and 18 mol% or less with respect to the total mol amount of the magnetic particles, for example, an alloy such as Co, Cr, and Pt calculated as one compound.

As the magnetic layers 34a, 34b, and 34c, it is preferable to use a material mainly containing Co and further containing an oxide. Examples of the oxide include Cr, Si, Ta, Al, Ti, Mg, and Co. The oxide is preferably used. Among _{them, TiO 2, Cr 2 O 3} , SiO ₂ or the like can be suitably used. The lower magnetic layer 34a is preferably made of a composite oxide to which two or more types of oxides are added. Among these, Cr ₂ O ₃ —SiO ₂ , Cr ₂ O ₃ —TiO ₂ , Cr ₂ O ₃ —SiO ₂ —TiO _{2 and the} like can be preferably used.

As a material suitable for the magnetic layers 34a, 34b, and 34c, for example, 90 (Co14Cr18Pt) -10 (SiO ₂ ) {Cr content of 14 atomic%, Pt content of 18 atomic%, and the balance Co consisting of one magnetic particle. molar concentrations calculated as compound 90 mol%, 10 _mol% oxide composition consisting _{SiO 2}, 92 (Co10Cr16Pt)} -8 (SiO 2), other _{94 (Co8Cr14Pt4Nb) -6 (Cr 2} O 3), (CoCrPt _{) - (Ta 2 O 5)} , (CoCrPt) - (Cr 2 O 3) - (TiO 2), (CoCrPt) - (Cr 2 O 3) - (SiO 2), (CoCrPt) - (Cr 2 O 3 _{) - (SiO 2) - (} TiO 2), (CoCrPtMo) - (TiO), (CoCrPtW) - (TiO 2), (CoCr _{tB) - (Al 2 O 3} ), (CoCrPtTaNd) - (MgO), (CoCrPtBCu) - (Y 2 O 3), (CoCrPtRu) - can be exemplified compositions such as (SiO _2).

  In the present invention, the perpendicular magnetic layer 34 may be composed of four or more magnetic layers. For example, in addition to the magnetic layers 34a and 34b, a magnetic layer having a granular structure is composed of three layers, and a magnetic layer 34c containing no oxide is provided thereon, and a magnetic layer containing no oxide is also provided. The layer 34c may have a two-layer structure and be provided on the magnetic layers 34a and 34b.

  In the present invention, it is preferable to provide a nonmagnetic layer 37 between three or more magnetic layers constituting the perpendicular magnetic layer 34. By providing the nonmagnetic layer 37 with an appropriate thickness, the magnetization reversal of individual films can be facilitated, and the dispersion of the magnetization reversal of the entire magnetic particles can be reduced. As a result, the S / N ratio can be further improved.

The protective layer 35 is for preventing corrosion of the perpendicular magnetic layer 34 and preventing damage to the medium surface when the magnetic head comes into contact with the magnetic recording medium W. For the protective layer 35, a conventionally known material can be used. For example, a material containing C, SiO ₂ , ZrO ₂ or the like can be used. The thickness of the protective layer 35 is preferably 1 to 10 nm from the viewpoint of high recording density because the distance between the magnetic head and the magnetic recording medium W can be reduced.

  The lubricant film 36 is formed, for example, by applying a lubricant such as perfluoropolyether, fluorinated alcohol, or fluorinated carboxylic acid on the protective layer 35.

(Magnetic recording / reproducing device)
Next, FIG. 5 shows an example of a magnetic recording / reproducing apparatus (hard disk drive) including the magnetic recording medium W manufactured by applying the present invention.
This magnetic recording / reproducing apparatus records and reproduces information on the magnetic recording medium 70 manufactured by applying the present invention shown in FIG. 4, a medium driving unit 71 that rotationally drives the magnetic recording medium 70, and the magnetic recording medium 70. And a recording / reproducing signal processing system 74. The head driving unit 73 moves the magnetic head 72 relative to the magnetic recording medium 70. Further, the recording / reproducing signal processing system 74 can process data input from the outside and send a recording signal to the magnetic head 72, and can process a reproducing signal from the magnetic head 72 and send the data to the outside. ing. Further, as the magnetic head 72 provided in the magnetic recording / reproducing apparatus, a magnetic head suitable for a higher recording density having a GMR element utilizing a giant magnetoresistive effect (GMR) as a reproducing element can be used.

  According to the magnetic recording / reproducing apparatus, an excellent magnetic recording medium W manufactured by applying the present invention to the magnetic recording medium 70 having high recording density, high speed writing, and excellent electromagnetic conversion characteristics can be used. It can be a hard disk drive.

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

Example 1
In Example 1, first, a cleaned glass substrate (manufactured by Konica Minolta Co., Ltd., 2.5 inches in outer diameter) is accommodated in a film forming chamber of a DC magnetron sputtering apparatus (C-3040 made by Anelva Co., Ltd.), and the ultimate vacuum is achieved. After evacuating the film formation chamber to 1 × 10 ⁻⁵ Pa, an adhesion layer having a thickness of 10 nm was formed on the glass substrate using a 60Cr-40Ti target. Further, on this adhesion layer, a target of 46Fe-46Co-5Zr-3B {Fe content 46 atomic%, Co content 46 atomic%, Zr content 5 atomic%, B content 3 atomic%} was used. A soft magnetic layer having a layer thickness of 34 nm was formed at a substrate temperature of 100 ° C. or less, and a Ru layer was formed thereon with a layer thickness of 0.76 nm, and then a 46Fe-46Co-5Zr-3B soft magnetic layer was further formed. A film thickness of 34 nm was formed and used as a soft magnetic underlayer.

  Next, on the soft magnetic underlayer, Ni-6W {W content 6 atom%, balance Ni} target and Ru target were sequentially formed with a layer thickness of 5 nm and 20 nm, respectively, and these were oriented. The control layer was used.

Then, on the orientation control layer, a magnetic layer of a multilayer structure, Co12Cr16Pt-16TiO ₂ (film thickness _{3nm), Co5Cr22Pt-4SiO 2 -3Cr} 2 O 3 -2TiO 2 ( film thickness 3nm), Ru47.5Co (film Co15Cr16Pt6B (film thickness 3 nm) was laminated.
Next, a carbon protective layer having a thickness of 2.5 nm was formed by CVD, and the magnetic recording medium of Example 1 was obtained.

  Next, a lubricant film made of perfluoropolyether was formed to a thickness of 15 Å on the surface of the magnetic recording medium by dipping.

  Next, a wiping process was performed on the magnetic recording medium coated with the lubricant. As the wiping tape, a peelable composite fiber having a wire diameter of 2 μm made of nylon resin and polyester resin was used. In the wiping process, the rotational speed of the magnetic recording medium was 300 rpm, the wiping tape feed speed was 10 mm / second, the pressing force when pressing the wiping tape against the magnetic recording medium was 98 mN, and the processing time was 5 seconds.

  Next, a burnishing process was performed on the magnetic recording medium subjected to the wiping process. The burnish tape used was a polyethylene terephthalate film on which crystal growth type alumina particles having an average particle size of 0.5 μm were fixed with an epoxy resin. In the burnishing process, the rotation speed of the magnetic recording medium was 300 rpm, the feeding speed of the polishing tape was 10 mm / second, the pressing force when pressing the polishing tape against the magnetic disk was 98 mN, and the processing time was 5 seconds.

  Next, a wiping process using microbeads was performed on the magnetic recording medium subjected to the burnish process. As the wiping tape, a tape-like support made of a polyethylene terephthalate film having a thickness of 20 μm was used in which acrylic beads having an average particle diameter of 3 μm were fixed in layers. In the wiping process, the rotation speed of the magnetic recording medium was 200 rpm, the polishing tape feed speed was 10 mm / second, the pressing force when pressing the polishing tape against the magnetic disk was 70 mN, and the processing time was 5 seconds.

  Next, a servo signal or the like was written by magnetic transfer on a magnetic recording medium subjected to wiping processing using microbeads. Specifically, initial magnetization was applied to both data surfaces of the magnetic recording medium using an NdFeB-based sintered magnet while applying a 10 kOe magnetic field penetrating the magnetic recording medium.

  Then, the master information carrier was brought into close contact with both surfaces of the magnetic recording medium subjected to initial magnetization at a pressure of 98 mN, and a recording magnetic field was applied from the back surface of the master information carrier. The intensity of this recording magnetic field was 4 kOe, and the transfer time was 10 seconds.

A master information carrier having a transfer pattern such as a 271k track / inch servo signal was used. The master information carrier has a track width of 120 nm, a track interval of 60 nm, and a transfer pattern step of 45 nm. This master information carrier is made of a Ru film having a thickness of 10 nm and a 70Co-5Cr-15Pt-10SiO ₂ alloy having a thickness of 20 nm as a magnetic layer on a Ni substrate having a convex portion and a concave portion using a DC sputtering method. The film and an 80Co-5Cr-15Pt alloy film having a layer thickness of 15 nm are sequentially laminated, and then a CVD carbon film having a layer thickness of 20 nm is formed thereon as a protective layer.

The reproduction characteristics such as servo signals of the magnetic recording medium produced by the above method were measured using a read / write analyzer (model number: RWA1632; manufactured by GUZIK, USA) and a spin stand (model number: S1701MP). In this apparatus, a servo signal or the like recorded on a magnetic recording medium is read, and the magnetic head can be positioned using this signal. At this time, a magnetic head using TuMR is used as an evaluation magnetic head, and the S / N ratio at the time of servo signal reading is evaluated. When the S / N ratio is 16.0 dB or less, magnetic transfer is performed. Judged to be bad.
As a result, in Example 1, 121,000 times of magnetic transfer were possible.

(Comparative Example 1)
In Comparative Example 1, magnetic transfer was performed on a magnetic recording medium produced under the same conditions as in Example 1 except that the wiping process using the microbeads was not performed.
As a result, in Comparative Example 1, 25,000 times of magnetic transfer were possible.

DESCRIPTION OF SYMBOLS 1 ... Wiping tape 2 ... Support body 3 ... Microbead 4 ... Binder 5 ... Bead layer 6 ... Lubricant 20 ... Wiping tape 21 ... Medium rotation drive mechanism 22 ... Tape running mechanism 23 ... Tape pushing mechanism 24 ... Spindle 25 ... Chuck part 26a-26d ... Guide roll 27 ... Pressing pad 28 ... Oscillating arm 31 ... Non-magnetic substrate 32 ... Soft magnetic underlayer 32a ... Soft magnetic layer 32b ... Spacer layer 33 ... Orientation control layer 34 ... Vertical magnetic layer 34a, 34b, 34c ... Magnetic layer 35 ... Protective layer 36 ... Lubricant film 37a, 37b ... Nonmagnetic layer 38 ... Nonmagnetic underlayer 70 ... Magnetic recording medium 71 ... Medium drive unit 72 ... Magnetic head 73 ... Head drive unit 74 ... Recording Reproduction signal processing system 100 ... Ni base material 100a ... convex portion 100b ... concave portion 101 ... magnetic layer 200 ... nonmagnetic substrate 201 ... magnetic layer W ... magnetic Gas recording medium M ... Master information carrier G ... Magnetic field generating means

Claims (4)

After superimposing a magnetic recording medium having at least a magnetic layer on a non-magnetic substrate and a master information carrier on which a transfer pattern corresponding to an information signal is formed, an external magnetic field is applied from the master information carrier side. However, a method of manufacturing a magnetic recording medium including a step of magnetically transferring an information signal from the master information carrier to the magnetic recording medium,
Using a master information carrier that can be repeatedly used when performing the magnetic transfer, and before superimposing the master information carrier and the magnetic recording medium, using a wiping tape having microbeads fixed to the surface of the support, A method of manufacturing a magnetic recording medium, comprising a wiping step of wiping the surface of the magnetic recording medium.   2. The method of manufacturing a magnetic recording medium according to claim 1, wherein a lubricant is applied to the wiping tape.   3. The wiping tape, wherein a microbead made of an acrylic resin having an average particle diameter of 2 to 3 [mu] m is fixed to the surface of a support made of a resin film with a binder. A method for producing the magnetic recording medium according to 1.   Prior to the wiping step, another magnetic wiping step using a cloth wiping tape and a burnish tape having abrasive grains fixed on the surface of the support are used. The method of manufacturing a magnetic recording medium according to claim 1, further comprising a burnishing step for polishing the surface of the recording medium.

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