JP2011227964A - Method for manufacturing magnetic recording medium - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for manufacturing a magnetic recording medium by which a frequency repeatedly transferrable by one master information carrier is drastically increased.SOLUTION: A method for manufacturing a magnetic recording medium W comprises a process to magnetically transfer an information signal to the magnetic recording medium W from a master information carrier M while applying an external magnetic field from the master information carrier M side, after the magnetic recording medium W in which at least a magnetic layer is formed on a non-magnetic substrate, and the master information carrier M in which a transfer pattern corresponding to the information signal are formed, are laminated. The master information carrier M repeatedly usable at the magnetic transfer operation is used and also such a process is provided that a cleaning fluid containing alkaline detergent is used before the master information carrier M and the magnetic recording medium W are laminated, and the magnetic recording medium W is cleaned while immersing the magnetic recording medium in a cleaning tank in which the cleaning fluid flows in the laminar flowing state.

Description

  The present invention relates to a method of manufacturing a magnetic recording medium, and more particularly to a technique for cleaning a magnetic recording medium before performing magnetic transfer.

  The recording density of a hard disk drive (hard disk drive), which is a kind of magnetic recording / reproducing apparatus, is currently increasing 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 has reached 320 kTPI.

  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 Japanese Patent Laid-Open No. 10-106229 Japanese Patent Laid-Open No. 11-277339

  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 surface of the magnetic recording medium is burnished to remove protrusions and dust on the surface, and then the master information carrier is superposed on the magnetic recording medium for magnetic transfer, thereby using the master information carrier. It has been proposed to increase the number of times (for example, see Patent Document 2).

  Here, the cleaning of the substrate surface and the like performed in the manufacturing process of the magnetic recording medium is roughly classified into wet cleaning using a cleaning liquid and dry cleaning using a wiping tape or the like. Although the former wet cleaning is superior to the latter dry cleaning, the dirt removed from the magnetic recording medium contained in the cleaning liquid may reattach to the medium surface. For this reason, wet cleaning is mainly used for cleaning nonmagnetic substrates for magnetic recording media such as aluminum alloy and glass, which do not require so high cleaning performance, as described in Patent Document 3, for example.

  In addition, wet cleaning may be used for cleaning the magnetic recording medium. However, in order to prevent re-attachment of corrosion and dirt such as Fe and Co contained in the magnetic recording medium, a short time of about several seconds using pure water. Limited to spin cleaning. Further, many particles such as sputter dust adhere to the surface of the magnetic recording medium, and wiping using a woven fabric or a non-woven fabric is considered to be more effective for removing these particles. .

  However, according to the study by the present inventors, by performing the above-described burnishing treatment on the surface of the magnetic recording medium, wiping treatment using a woven cloth or the like on the surface of the magnetic recording medium and the master information carrier, wet cleaning, etc. It has been found that even when the protrusions and dust on the surface are removed, the transfer pattern becomes incomplete before the master information carrier is damaged due to wear. In this case, it is still difficult to increase the total number of times that can be repeatedly transferred by one master information carrier to a number of times that is sufficient to be applied to commercial production.

  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 due to ions represented by metal corrosives adhering to the surface of the master information carrier. It was elucidated that the slightly corroded metal residue on the surface of the magnetic recording medium was transferred and accumulated little by little on the master information carrier. In addition, metal corrosives and the like slightly remaining on the surface of the magnetic recording medium are of a level that cannot be removed by normal burnishing, wiping, cleaning, etc., and these are accumulated little by little on the master information carrier, It has been clarified that it is difficult to remove these substances by entering the recesses of the information carrier and wiping the transfer surface of the master information carrier. Furthermore, it has been elucidated that the accumulated material entering the concave portion of the master information carrier gradually erodes the convex portion of the master information carrier and reduces the transfer accuracy by the master information carrier.

  Therefore, the present inventors use a cleaning liquid containing an alkaline cleaning agent and perform magnetic recording in a cleaning tank in which the cleaning liquid flows in a laminar flow before magnetic transfer to the magnetic recording medium using the master information carrier. By providing a step of cleaning the magnetic recording medium while immersing the medium, it is possible to prevent the metal corrosive matter remaining slightly on the surface of the magnetic recording medium from being transferred to the master information carrier. It has been found that the number of times of use can be dramatically improved, 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 step of magnetically transferring an information signal from the master information carrier to the magnetic recording medium while applying
A master information carrier that can be used repeatedly when performing the magnetic transfer is used, and before superimposing the master information carrier and the magnetic recording medium, a cleaning liquid containing an alkaline cleaning agent is used, and the cleaning liquid is in a laminar flow state. A method of manufacturing a magnetic recording medium, comprising: a step of cleaning the magnetic recording medium while immersing the magnetic recording medium in a cleaning tank flowing through
(2) The method for manufacturing a magnetic recording medium according to (1), wherein the magnetic recording medium is cleaned while a cleaning liquid is allowed to flow laterally in the cleaning tank.
(3) The flow rate of the cleaning liquid flowing through any one of the supply ports and / or the discharge ports among the plurality of supply ports for supplying the cleaning liquid to the cleaning tank and the plurality of discharge ports for discharging the cleaning liquid from the cleaning tank is adjusted. By doing so, the cleaning liquid in the cleaning tank flows in a laminar flow state. The method for manufacturing a magnetic recording medium according to item (2), wherein
(4) The preceding item (1), wherein the alkaline detergent contains at least one of potassium hydroxide, sodium hydroxide, sodium carbonate, potassium carbonate, ammonia, and tetramethylammonium hydroxide as an active ingredient. )-(3) The manufacturing method of the magnetic-recording medium as described in any one.
(5) The method for producing a magnetic recording medium according to (4), wherein the concentration of the alkaline detergent in the cleaning liquid is in the range of 0.000001 mass% to 0.1 mass%.
(6) The magnetic recording medium is cleaned with a cleaning liquid containing the alkali cleaning agent, and then the magnetic recording medium is cleaned with pure water. The method for producing a magnetic recording medium according to any one of the above.
(7) The method for manufacturing a magnetic recording medium according to any one of (1) to (6), wherein ultrasonic vibration is applied to the cleaning liquid in the cleaning tank.

  As described above, in the present invention, a master information carrier that can be used repeatedly when performing magnetic transfer is used, and before superimposing the master information carrier and the magnetic recording medium, a cleaning liquid containing an alkaline cleaner is used, In addition, by providing a step of cleaning the magnetic recording medium while immersing the magnetic recording medium in a cleaning tank in which the cleaning liquid flows in a laminar flow state, metal corrosives slightly remaining on the surface of the magnetic recording medium are provided. It can be removed efficiently.

  Therefore, according to the present invention, when the master information carrier and the magnetic recording medium are superimposed, it is possible to prevent metal corrosives and the like from being transferred from the magnetic recording medium to the master information carrier. It is possible to dramatically increase the number of times that the information carrier can be repeatedly transferred. As a result, an effect of greatly reducing the production cost of the magnetic recording medium can be obtained.

FIG. 1 is a plan view showing a configuration of a flowing water type cleaning apparatus to which the present invention is applied. FIG. 2 is a cross-sectional view showing a configuration of a flowing water type cleaning apparatus to which the present invention is applied. FIG. 3 is a cross-sectional view for explaining the turbulent flow generated in the cleaning tank. FIG. 4 is a plan view for explaining the turbulent flow generated in the cleaning tank. FIG. 5 is a cross-sectional view for explaining the magnetic transfer process of the present invention. FIG. 6 is a cross-sectional view showing an example of a magnetic recording medium. FIG. 7 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. The method includes a step of magnetically transferring an information signal from the master information carrier to a magnetic recording medium while applying an external magnetic field from the master information carrier side (referred to as a magnetic transfer step). A master information carrier that can be used repeatedly is used, and before superimposing the master information carrier and the magnetic recording medium, a cleaning liquid containing an alkaline cleaning agent is used, and the cleaning liquid flows magnetically in a laminar flow state. A step of cleaning the magnetic recording medium while dipping the recording medium (referred to as a medium cleaning step) is provided.

(Medium washing process)
Specifically, in the medium cleaning process of the present invention, a wet cleaning of the magnetic recording medium is performed using a cleaning liquid containing an alkaline cleaning agent and immersing the magnetic recording medium in a cleaning tank in which the cleaning liquid flows in a laminar flow state. I do. As a result, a small amount of contaminants remain on the surface of the magnetic recording medium and cannot be removed by burnishing, wiping, spin cleaning, conventional wet cleaning, etc., especially ions represented by metal corrosion. Can be efficiently removed.

  In the present invention, it is preferable to clean the magnetic recording medium while flowing the cleaning liquid in the horizontal direction in the cleaning tank. In this case, since the cleaning liquid containing the contaminant can be quickly discharged out of the immersion tank, it is possible to prevent the contaminant from reattaching to the surface of the magnetic recording medium. As a result, it is possible to obtain a magnetic recording medium having a clean surface that cannot be obtained by conventional methods.

Here, for example, an example of the flowing water type cleaning apparatus 1 used in the medium cleaning process of the present invention as shown in FIGS. 1 and 2 will be described.
This flowing water type cleaning apparatus 1 is preferably used for cleaning a magnetic recording medium W mounted on a hard disk drive (magnetic recording / reproducing apparatus) before the transfer step, and holds the magnetic recording medium W. The cleaning tank 2 for cleaning the magnetic recording medium W by immersing the holder 50 in the cleaning liquid L is provided.

  The holder 50 holds a plurality of disk-shaped magnetic recording media W formed with a center hole in parallel with each other. Each magnetic recording medium W is supported by a pair of support plates 51a and 51b provided on the holder 50 at outer peripheral portions on both sides across a vertical center line passing through the center hole. The pair of support plates 51a and 51b are provided with V-shaped grooves (not shown) with which the outer peripheral portions of the respective magnetic recording media W are engaged.

  Each magnetic recording medium W is supported by the pair of support plates 51a and 51b, and is held by the holder 50 in a vertically placed state (a state where the main surface of the magnetic recording medium W is parallel to the vertical direction). . The holder 50 is disposed on the bottom surface of the cleaning tank 2 so that the main surface of each magnetic recording medium W is parallel to the direction in which the cleaning liquid L flows. FIG. 1 shows a state in which five magnetic recording media W are arranged in one row, but in an actual example, magnetic recording media W having a diameter of 3.5 inches are 50 in one row at intervals of about 5 mm. About one sheet is arranged and held in the holder 50.

  The cleaning tank 2 has a rectangular bottom wall 2a, four side walls 2b, 2c, 2d, and 2e that rise from the periphery of the bottom wall 2a, and an opening 2f on the upper surface that faces the bottom wall 2a. Is formed in a substantially rectangular parallelepiped shape, and a substantially rectangular parallelepiped immersion space S in which the holder 50 is immersed is formed inside.

  A plurality of supply ports 3 for supplying the cleaning liquid L are provided on the upstream side wall 2 b of the cleaning tank 2. The plurality of supply ports 3 are arranged at predetermined intervals in the width direction and the height direction of the side wall 2b. Further, a flow rate adjusting valve (flow rate adjusting means) 4 is connected to each supply port 3, and the flow rate of the cleaning liquid L supplied from each supply port 3 by adjusting the opening degree of the flow rate adjusting valve 4. Can be adjusted individually.

  A plurality of outlets 5 for discharging the cleaning liquid L are provided in the side wall 2d on the downstream side of the cleaning tank 2. The plurality of discharge ports 5 are arranged side by side at a predetermined interval in the width direction and the height direction of the side wall 2d. Further, a flow rate adjusting valve (flow rate adjusting means) 6 is connected to each discharge port 5, and the flow rate of the cleaning liquid L discharged from each supply port 3 by adjusting the opening degree of the flow rate adjusting valve 6. Can be adjusted individually.

  In the present embodiment, the supply port 3 and the discharge port 5 are arranged in 7 rows at intervals of 5 cm in the width direction and 6 rows at intervals of 5 cm in the height direction, at positions opposite to the side walls 2b and 2d, respectively. However, the arrangement, number, interval, and the like of the supply port 3 and the discharge port 5 can be changed as appropriate.

  The bottom wall 2a of the cleaning tank 2 is provided with an ultrasonic oscillator (ultrasonic generator) 7 that applies ultrasonic vibrations to the cleaning liquid L in the immersion space S in order to enhance the cleaning capability for the magnetic recording medium W. ing. The ultrasonic oscillator 7 applies ultrasonic vibration of about 500 W at 200 kHz to the cleaning liquid L in the cleaning tank 2 from the bottom wall 2a side of the cleaning tank 2, for example.

  Further, in this flowing water type cleaning apparatus 1, as a mechanism for cyclically reusing the cleaning liquid L flowing in the cleaning tank 2, the cleaning liquid L discharged from the discharge port 5 is sucked and pumped again to the supply port 3. And a filter 9 for purifying the cleaning liquid L pumped by the pump 8.

  In the medium cleaning process of the present invention, the plurality of magnetic recording media W held by the holder 50 are cleaned using the flowing water type cleaning apparatus 1 having the above structure. Specifically, in the medium cleaning process using the flowing water type cleaning device 1, the cleaning liquid L is caused to flow in the lateral direction (horizontal direction) in a laminar flow in the immersion space S of the cleaning tank 2, and ultrasonic vibrations are generated in the cleaning liquid L. The holder 50 holding the plurality of magnetic recording media W is immersed in the cleaning liquid L in the immersion space S.

  At this time, in the cleaning tank 2, the main surface of each magnetic recording medium W held by the holder 50 is parallel to the flowing direction of the cleaning liquid L, and the cleaning liquid L in a laminar flow state is formed between these magnetic recording media W. Will flow. As a result, the surface of each magnetic recording medium W is cleaned with the cleaning liquid L, and remains slightly on the surface of the magnetic recording medium W described above in addition to the dust and foreign matter adhering to the surface of each magnetic recording medium W. In addition, it is possible to efficiently remove contaminants of a level that cannot be removed by burnishing, wiping, spin cleaning, conventional wet cleaning, etc., particularly ionic impurities typified by metal corrosion. .

  Further, in this flowing water type cleaning apparatus 1, the cleaning liquid containing the contaminants and impurities described above is removed from the cleaning tank 2 in order to clean the magnetic recording medium W while flowing the cleaning liquid L in the cleaning tank 2 in the lateral direction. It is possible to discharge quickly. Thereby, it is possible to prevent the contaminants from reattaching to the surface of the magnetic recording medium W, and as a result, it is possible to obtain the magnetic recording medium W having a clean surface that cannot be obtained by the conventional method. It is.

  By the way, when ultrasonic vibration is applied from the bottom surface side of the cleaning tank 2, the liquid level of the cleaning liquid L in the cleaning tank 2 rises, thereby causing the cleaning liquid L flowing in the cleaning tank 2 to be turbulent and magnetic recording medium. The inventors' analysis has revealed that the cleaning ability for W is reduced.

  Specifically, according to the analysis by the present inventors, when the cleaning liquid L is caused to flow in a laminar flow state in the cleaning tank 2 without applying ultrasonic vibration, and then the ultrasonic vibration is applied, the flow of the cleaning liquid L As shown by the direction of the arrow in FIG. 3, the ultrasonic vibration is applied from the bottom surface side of the cleaning tank 2, so that the liquid level of the cleaning liquid L in the cleaning tank 2 rises. However, since a laminar flow is added to the flow of the cleaning liquid L, a complicated flow (turbulent flow) is generated in the cleaning tank 2. Further, as shown in FIG. 4, when the magnetic recording medium W is immersed in the cleaning tank 2, the cleaning liquid L flowing in the cleaning tank 2 is turbulent by the magnetic recording medium W and becomes a turbulent flow. As a result, the cleaning ability for the magnetic recording medium W is lowered.

  FIG. 3 shows the flow of the cleaning liquid L when ultrasonic vibration is applied to the cleaning tank 2 when the cleaning tank 2 is viewed from the side. On the other hand, in FIG. 4, when the cleaning tank 2 is viewed from the upper surface side, the upper layer flow of the cleaning liquid L flowing in the cleaning tank 2 is represented by a broken line, the middle layer flow is represented by an alternate long and short dash line, and the lower layer flow is represented by This is represented by a two-dot chain line.

  Therefore, in the present invention, as shown in FIGS. 1 and 2, the flow rate of the cleaning liquid L flowing through any one of the supply ports 3 and / or the discharge ports 5 is adjusted while controlling the flow rate adjusting valves 4 and 6 described above. The flow of the cleaning liquid L in the cleaning tank 2 is adjusted so that the flow of the cleaning liquid L becomes a uniform flow (laminar flow) without disturbance.

  Thereby, it is possible to flow the cleaning liquid L in the cleaning tank 2 from a turbulent state to a laminar state. In particular, in the present invention, in addition to the supply of the cleaning liquid L from the supply port 3, the flow of the cleaning liquid L from the discharge port 5 is controlled by the flow rate adjusting valves 4, 6. Can be formed with higher controllability, and the laminar flow can be prevented from being disturbed by the ultrasonic vibration or the arrangement of the object to be cleaned.

  Moreover, in this invention, it is preferable to reuse the washing | cleaning liquid L which flows into the washing tank 2 cyclically like the said flushing-type washing | cleaning apparatus 1. FIG. Thus, it becomes easy to quantitatively balance the cleaning liquid L supplied to the cleaning tank 2 and the cleaning liquid L discharged from the cleaning tank 2, and the cleaning liquid L flowing in the cleaning tank 2 is more laminar. It becomes possible to flow stably.

  In the case of the flowing water type cleaning apparatus 1, the cleaning liquid L slightly decreases due to evaporation of the cleaning liquid L from the opening 2f of the cleaning tank 2, and therefore it is preferable to replenish the reduced amount of the cleaning liquid L as appropriate. . In the flowing water type cleaning apparatus 1, a lid can be provided on the opening 2 f of the cleaning tank 2 in order to prevent bubbles from entering the cleaning liquid L due to contact between the cleaning liquid L and air.

  Further, in the present invention, when cleaning a plurality of magnetic recording media W held in parallel in the holder 50 described above, the interval between the plurality of magnetic recording media W held by the holder 50 is determined. Is preferably dense to the extent that the flow resistance of the cleaning liquid L flowing therebetween increases.

  For example, when cleaning a disk-shaped magnetic recording medium W having a diameter of 3.5 inches and a plate thickness of 1.27 mm, the flow resistance of the cleaning liquid starts to increase remarkably when the distance between the substrate surfaces becomes 10 mm or less. .

  On the other hand, in the conventional flowing water type cleaning method, in order to stabilize the laminar flow of the cleaning liquid flowing in the cleaning tank 2, the objects to be cleaned arranged in the cleaning tank 2 are arranged sparsely at intervals. It has been common to provide a space around an object to be cleaned disposed in a cleaning tank. This is for reducing the flow resistance distribution due to the presence or absence of the object to be cleaned in the cleaning tank and stabilizing the laminar flow of the cleaning liquid L flowing in the cleaning tank.

  On the other hand, in the flowing water type cleaning method of the present invention, the substrate (object to be cleaned) W is densely arranged in the cleaning tank 2, thereby increasing the water flow resistance of the cleaning liquid L flowing in the cleaning tank 2, and In this state, a strong and uniform laminar flow is formed by supplying the cleaning liquid L from the supply port 3 and forcibly discharging the cleaning liquid L from the discharge port 5. Thereby, it is possible to stabilize the laminar flow of the cleaning liquid L flowing in the cleaning tank 2 and to increase the cleaning ability of the cleaning tank 2.

  In the present invention, it is preferable that the shortest distance between the inner surface of the cleaning tank 2 and the magnetic recording medium W is not more than one time the diameter of the magnetic recording medium W. In particular, in the present invention, when cleaning a disk-shaped magnetic recording medium W as an object to be cleaned, the magnetic recording medium W is arranged so that the main surface of the magnetic recording medium W is parallel to the direction in which the cleaning liquid L flows. The magnetic recording medium W is placed in the cleaning tank 2 and the shortest distance between the inner surface of the cleaning tank 2 and the magnetic recording medium W is less than or equal to one times the diameter of the magnetic recording medium W. It becomes possible to wash.

  The flowing water type cleaning device used in the medium cleaning process of the present invention is not necessarily limited to the configuration of the above flowing water type cleaning device 1, and various modifications can be made without departing from the spirit of the present invention. Is possible.

  For example, the holder 50 is configured to support the outer peripheral portion of each magnetic recording medium W at two points by a pair of support plates 51a and 51b. The position and the number of the outer peripheral portion to be supported can be changed as appropriate. For example, the outer peripheral portion of each magnetic recording medium W can be supported at three points or supported at four points. Is possible.

  Further, the member that supports the outer peripheral portion of each magnetic recording medium W is not limited to the support plates 51a and 51b, and does not disturb the flow of the cleaning liquid L flowing in the cleaning tank 2. If there is, the shape and the like can be changed as appropriate.

  In the medium cleaning step of the present invention, it is preferable to use a cleaning liquid L containing an alkaline cleaning agent for cleaning the magnetic recording medium W. This is slightly left on the surface of the magnetic recording medium W and cannot be removed by burnishing, wiping, spin cleaning, or the like, especially ionic impurities such as metal corrosives. This is because the corrosion of the magnetic layer containing Fe, Co and the like can be reduced by using the cleaning liquid L containing the alkaline cleaner, and these contaminants can be removed with high cleaning power. .

  Alkaline detergent is a detergent whose liquidity is alkaline. Generally, a surfactant such as polyoxyethylene alkyl ether, an alkali component such as NaOH or KOH, a solvent such as glycol ether, and a thickening agent. Including agents. In this invention, what contains potassium hydroxide, sodium hydroxide, sodium carbonate, potassium carbonate, ammonia, tetramethylammonium hydroxide etc. can be used as an active ingredient of an alkali cleaning agent, and by using these, A high cleaning effect can be obtained.

  Since the magnetic recording medium contains the above-described easily corroding elements such as Fe and Co, cleaning of the magnetic recording medium has been limited to cleaning with a non-aqueous cleaning liquid using a fluorine compound or the like. In the present invention, since a cleaning liquid containing an alkaline cleaning agent is used, the magnetic recording medium is hardly corroded by the cleaning liquid, and contaminants attached to the surface of the magnetic recording medium can be removed with high cleaning power. In particular, by setting the concentration of the alkaline cleaning agent in the cleaning liquid in the range of 0.000001 mass% (0.01 ppm) to 0.1 mass% (1000 ppm), the effect can be enhanced, and more preferably The range is 0.1 to 20 ppm. On the other hand, when the concentration of the alkaline detergent in the cleaning liquid is less than 0.01 ppm, the cleaning effect is reduced. Conversely, when the concentration of the alkaline cleaning agent in the cleaning liquid exceeds 1000 ppm, the alkaline cleaning agent becomes a magnetic recording medium. This causes contamination of the magnetic recording medium and the master information carrier.

  Further, the medium washing process of the present invention may be a multistage process. Specifically, after cleaning the magnetic recording medium using a cleaning liquid containing an alkaline cleaner, the magnetic recording medium is subjected to an extremely short time such as spin cleaning using pure water or pulling and drying using dry air. It is preferable to perform immersion cleaning for a period of time. In the medium cleaning step of the present invention, the cleaning power can be increased by adding an alkaline cleaning agent to the cleaning liquid. However, if these alkaline cleaning agents remain on the surface of the magnetic recording medium, this causes contamination of the magnetic recording medium and the master information carrier.

  In order to prevent this, in the present invention, after the magnetic recording medium is cleaned using a cleaning liquid containing an alkaline cleaner, spin cleaning using pure water or immersion cleaning for a very short time is performed on the magnetic recording medium. By performing the above, it is possible to increase the detergency of the magnetic recording medium without leaving alkali on the surface of the magnetic recording medium. After the cleaning, it is preferable to quickly dry the magnetic recording medium using a spin drying method, a dry air drying method, or the like.

  As described above, in the medium cleaning process of the present invention, in addition to the dust and foreign matter adhering to the surface of the magnetic recording medium W, it slightly remains on the surface of the magnetic recording medium W described above, burnishing, It is possible to efficiently remove an amount of contaminants that cannot be removed by wiping, spin cleaning, conventional wet cleaning, and the like, in particular, an organic polymer film adhering to the surface of the carbon film serving as a protective layer. In addition, after the cleaning, it is possible to perform advanced medium cleaning that prevents these from reattaching to the surface of the magnetic recording medium W. As a result, it is possible to obtain a magnetic recording medium W having a clean surface that cannot be obtained by a conventional method.

(Magnetic transfer process)
In the magnetic transfer process, a writing operation such as a servo signal is performed by magnetic transfer on the magnetic recording medium W whose surface is cleaned by the medium cleaning process 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. 5, 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.

  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 of the present invention, magnetic transfer is performed on the magnetic recording medium W whose surface has been highly cleaned by the medium cleaning process. Therefore, when the master information carrier M and the magnetic recording medium W are overlapped, It is possible to prevent the metal corrosive matter or the like slightly remaining on the surface of the magnetic recording medium W described above 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.

(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. 6, this 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 layers 32a and 32c, it is preferable to use a material containing Fe: Co in the range of 40:60 to 70:30 (atomic ratio). 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.

  By the way, in the conventional method of manufacturing a magnetic recording medium, a wiping process, a burnishing process, and a magnetic transfer process are performed after the above-described lubricant application process. In contrast, in the method of manufacturing a magnetic recording medium to which the present invention is applied, the medium cleaning step is performed before the magnetic transfer step. The medium washing step is preferably performed before the lubricant application step.

  That is, the medium cleaning process of the present invention is performed for the purpose of removing contaminants on the surface of the magnetic recording medium W that cannot be removed by the wiping process or the burnishing process. These contaminants may be difficult to clean and remove after the lubricant application process, wiping process, and burnishing process. The reason is that it is speculated that when the contaminant is covered with the lubricant film 36, it becomes difficult to remove it due to its water repellency. After the wiping process and the burnishing process, the contaminant is removed from the magnetic recording medium W. It is considered that it is applied to the surface and difficult to remove.

  In the medium cleaning process, it is possible to remove a certain amount of powdery substances such as sputter dust. However, the surface of the magnetic recording medium W is scrubbed, wiped, and scraped as in the wiping process and burnishing process. Since the effect is low, it is difficult to remove the powdery substance firmly attached to the surface of the magnetic recording medium W. Therefore, the medium cleaning step is preferably used in combination with the wiping step and the burnishing step.

  The wiping step is performed using a cloth wiping tape or the like as described in Patent Document 4, for example. That is, in this wiping step, the surface of the wiping tape is pressed against the surface of the magnetic recording medium W by a rubber contact roll or pad while the wiping tape is moved relative to the surface of the magnetic recording medium W. This is a process of lightly wiping the surface. By performing such processing, sputter dust and the like adhering to the surface of the magnetic recording medium W are removed, so that the flying height of the magnetic head can be further reduced.

  Further, as the wiping tape used in the wiping step, a wiping tape obtained by slitting a cloth made of ultrafine fibers into a belt shape, a woven or knitted fabric of ultrafine fiber multifilament yarn, or the like is used.

  In addition, the wiping method of the magnetic recording medium W using such a wiping tape is specifically the surface of the wiping tape (on the surface of the magnetic recording medium W on the magnetic layer side while rotating the magnetic recording medium W ( This is done by pressing the wiping surface. As a result, sputter dust and the like adhering to the surface of the magnetic recording medium W are wiped off, and the medium surface is cleaned.

  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 course of traveling from the supply reel side to the take-up reel side, the surface (back surface) opposite to the wiping tape wiping surface is pressed by a backing roll such as rubber or felt, and the wiping surface of the wiping tape becomes magnetic. It is pressed against the surface of the recording medium W.

  The burnishing step is a step of polishing the surface using a polishing tape in order to remove protrusions on the surface of the magnetic recording medium W. As a result, the flying height of the magnetic head in the hard disk drive is further reduced, and a gap is formed between the magnetic recording medium W and the master information carrier M in the magnetic transfer step, resulting in a blurred transfer pattern. It is possible to prevent M from being damaged.

  Such a burnishing process is performed using a polishing tape coated with alumina abrasive grains, as described in Patent Document 5, for example. That is, this burnishing step is a step of lightly polishing the surface of the medium by pressing the polishing tape against the surface of the magnetic recording medium W with a rubber contact roll. By performing such processing, abnormal protrusions and the like on the surface of the magnetic recording medium W are removed.

  As a polishing tape (burnish tape) used in the burnishing process, a tape formed by forming an abrasive layer on a polyester base film is usually used. Then, when this abrasive layer slides in contact with the surface of the magnetic recording medium W, fine dust adhering to the surface of the medium is removed, and abnormal protrusions etc. existing on the surface of the medium are polished and removed. Thus, the surface of the medium is smoothed.

  As an abrasive, chromium oxide, α-alumina, silicon carbide, nonmagnetic iron oxide, diamond, γ-alumina, α, γ-alumina, fused alumina, corundum, artificial, having an average particle size of about 0.05 μm to 50 μm Diamond or the like is used.

  Such burnishing is performed by pressing the abrasive surface of the polishing tape against the surface of the magnetic recording medium W while rotating the magnetic recording medium W. Thereby, the protrusions on the surface of the magnetic recording medium W are polished and removed, and the surface of the medium is smoothed. Here, the polishing 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 traveling from the supply reel side to the take-up reel side, the surface (back surface) opposite to the abrasive grain surface of the polishing tape is pressed by a backing roll such as rubber or felt, and the polishing surface of the polishing tape is It is pressed against the surface of the magnetic recording medium W.

  After the magnetic transfer step, 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 by actually flying the magnetic head to see if there are 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 / reproducing device)
Next, FIG. 7 shows an example of a magnetic recording / reproducing apparatus (hard disk drive) provided with the magnetic recording medium W manufactured by applying the present invention.
This magnetic recording / reproducing apparatus records and reproduces information on a magnetic recording medium 70 manufactured by applying the present invention shown in FIG. 6, a medium driving unit 71 that rotationally drives the magnetic recording medium 70, and a 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.

  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, 84 (Co12Cr16Pt) -16TiO ₂ (film thickness 3nm), Ru47.5Co (thickness 0.5nm), 91 (Co11.5Cr13Pt10Ru) -4SiO 2 -3Cr ₂ O ₃ -2TiO ₂ (film thickness: 3 nm) and Co15Cr16Pt6B (film thickness: 3 nm) were stacked.
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, the magnetic recording medium manufactured by the above method was cleaned using the flowing water type cleaning apparatus 1 shown in FIG. 1 and FIG. Specifically, a cleaning tank 2 made of SUS304 having a length of 40 cm, a width of 40 cm, and a depth of 35 cm is used, and a supply port 3 and a discharge port 5 each having a diameter of 15 mm are respectively relative to the side walls 2b and 2d of the cleaning tank 2. While facing each other, 7 rows are arranged at intervals of 5 cm in the width direction and 6 rows are arranged at intervals of 5 cm in the height direction, for a total of 42 (= 7 × 6), arranged in a grid, and each has flow control valves 4 and 6. It is connected. An ultrasonic oscillator 7 having a frequency of 950 kHz and an output of 600 W is disposed outside the bottom surface of the cleaning tank 2. As the filter 9, a 0.5 micron filter and an ion filter were used in each stage, and the cleaning liquid L flowing in the cleaning tank 2 was reused cyclically.

  Further, the magnetic recording medium W is held in the holder 50 by arranging 5 rows (total of 395 discs) as 39 per row in a direction orthogonal to the main surface at intervals of 10 mm, and then holding the holder 50 on the main recording medium W. It arrange | positioned on the bottom face of the washing tank 2 so that a surface might become parallel to the direction through which the washing | cleaning liquid L flows. Then, with the holder 50 immersed in the cleaning liquid L in the cleaning tank 2, the cleaning liquid L was caused to flow in a laminar flow in the lateral direction, and cleaning was performed while applying ultrasonic vibration to the cleaning liquid L.

  The water temperature of the cleaning liquid L is 23 ± 3 ° C., and the average flow speed of the cleaning liquid L flowing in a laminar state in the cleaning tank 2 (the flow speed in a state where the object to be cleaned is immersed and ultrasonic vibration is applied) is 3 m / The flow rate of the cleaning liquid L flowing through each supply port 3 and the discharge port 5 was adjusted while adjusting the opening degree of the flow rate adjusting valves 4 and 6 connected to each supply port 3 and the discharge port 5 so as to be equal.

  Specifically, as shown in Table 1, the opening degree of the flow rate adjusting valves 4 and 6 connected to the supply ports 3 and the discharge ports 5 was adjusted. Table 1 shows that when the upstream side wall 2b and the downstream side wall 2d are viewed from the inside of the cleaning tank 2, valve openings on the 42 supply ports 3 and the discharge port 5 side in the width direction and the height direction, respectively. Degree (%).

  The cleaning process of Example 1 uses a three-stage cleaning tank 2, each cleaning tank 2 uses ultrapure water as the cleaning liquid L, and the first-stage cleaning tank 2 contains KOH as an active ingredient. An alkaline detergent containing 1 ppm was added. The magnetic recording medium was immersed in this three-stage cleaning tank 2 in order, and each cleaning tank 2 was cleaned for 30 seconds. After washing, the magnetic recording medium was quickly pulled up with dry air and dried.

  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 feeding speed of the wiping tape 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. In the wiping treatment, perfluoropolyether was sprayed on the wiping tape to form a lubricant film of about 0.01 μm on the tape surface.

  Next, burnishing 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, the rotational speed of the magnetic recording medium was 300 rpm, the polishing tape feed speed was 10 mm / second, the pressing force when pressing the polishing tape against the magnetic disk was 98 mN, and the treatment time was 5 seconds.

  Next, a servo signal or the like was written by magnetic transfer on the burnished magnetic recording medium. 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 a 70Co-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 magnetic recording medium produced by the above method was periodically extracted and evaluated. Specifically, the reproduction characteristics such as servo signals 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, 88,000 times of magnetic transfer were possible.

(Example 2)
In Example 2, the magnetic recording produced under the same conditions as in Example 1 except that the opening degree of the flow rate adjusting valves 4 and 6 connected to the supply port 3 and the discharge port 5 of each cleaning tank 2 are all 50%. Magnetic transfer was performed on the medium.
As a result, in Example 2, 71000 times of magnetic transfer were possible.

(Comparative Example 1)
In Comparative Example 1, the same cleaning liquid L as in Example 1 was used in the cleaning step, but a four-surface overflow tank was used as the cleaning tank. Specifically, the cleaning liquid is supplied from 25 supply ports provided at the bottom of a cleaning tank made of SUS304 having a length of 40 cm, a width of 40 cm, and a depth of 35 cm, and the liquid used for cleaning is supplied in four directions from the upper surface of the tank. The discharged cleaning liquid was circulated in the same manner as in Example 1. The flow rate of the cleaning liquid supplied to the cleaning tank was 5 liters / minute. Otherwise, magnetic transfer was performed on the magnetic recording medium produced under the same conditions as in Example 1.
As a result, in Comparative Example 3, 49000 times of magnetic transfer were possible.

DESCRIPTION OF SYMBOLS 1 ... Running water type cleaning apparatus 2 ... Cleaning tank 3 ... Supply port 4 ... Flow rate adjustment valve (flow rate adjustment means) 5 ... Discharge port 6 ... Flow rate adjustment valve (flow rate adjustment means) 7 ... Ultrasonic oscillator (vibration generation means) 8 ... Pump 9 ... Filter 31 ... Nonmagnetic 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 Films 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 DESCRIPTION OF SYMBOLS ... Recessed part 101 ... Magnetic layer 200 ... Nonmagnetic substrate 201 ... Magnetic layer W ... Magnetic recording medium M ... Master information carrier G ... Magnetic field generation means

Claims (7)

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,
A master information carrier that can be used repeatedly when performing the magnetic transfer is used, and before superimposing the master information carrier and the magnetic recording medium, a cleaning liquid containing an alkaline cleaning agent is used, and the cleaning liquid is in a laminar flow state. A method of manufacturing a magnetic recording medium, comprising: a step of cleaning the magnetic recording medium while immersing the magnetic recording medium in a cleaning tank flowing through   The method of manufacturing a magnetic recording medium according to claim 1, wherein the magnetic recording medium is cleaned while a cleaning liquid is allowed to flow laterally in the cleaning tank.   By adjusting the flow rate of the cleaning liquid flowing through any one of the supply port and / or the discharge port among the plurality of supply ports for supplying the cleaning liquid to the cleaning tank and the plurality of discharge ports for discharging the cleaning liquid from the cleaning tank. The method of manufacturing a magnetic recording medium according to claim 2, wherein the cleaning liquid in the cleaning tank flows in a laminar state. The alkaline detergent contains at least one or more of potassium hydroxide, sodium hydroxide, sodium carbonate, potassium carbonate, ammonia, and tetramethylammonium hydroxide as active ingredients. The manufacturing method of the magnetic-recording medium as described in any one. 5. The method of manufacturing a magnetic recording medium according to claim 4, wherein the concentration of the alkaline cleaning agent in the cleaning liquid is in the range of 0.000001% by mass to 0.1% by mass.   6. The magnetic recording medium is cleaned with a cleaning liquid containing the alkaline cleaning agent, and then the magnetic recording medium is cleaned with pure water. A method for producing the magnetic recording medium according to 1.   The method for manufacturing a magnetic recording medium according to claim 1, wherein ultrasonic vibration is applied to the cleaning liquid in the cleaning tank.

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