JP2010182351A - Master disk - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To perform stable magnetic transfer many times by suppressing transfer of a lubricant from a slave disk to a master disk, and stably maintaining a surface state of the slave disk after execution of servo record signal transfer. <P>SOLUTION: The master disk has a non-magnetic substrate and a pattern corresponding to preformat information on a surface or a part of the surface of the non-magnetic substrate, and is used for magnetically transferring the preformat information on a magnetic recording layer of a surface of a magnetic recording medium. The master disk has a protective layer on its surface, and the surface of the protective layer has been subjected to fluorination treatment. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a magnetic transfer master disk, and more particularly to a magnetic recording device used as an external storage device of a computer, in particular, a servo signal, an address signal, and other ordinary data signals to a magnetic recording medium having a large capacity and a high recording density. The present invention relates to a master disk for magnetic transfer used for recording such as.

  In a general HDD device, a magnetic head is recorded and reproduced while flying over a surface of a rotating annular magnetic recording medium with a flying distance of several tens of nanometers by a flying mechanism called a slider. Is done.

  Bit information on the magnetic recording medium is stored in data tracks arranged concentrically on the magnetic recording medium. At the time of data recording / reproducing, the data recording / reproducing head is moved and positioned above the target data track at high speed. On the recording surface of the magnetic recording medium, preformat information such as a tracking servo signal, an address signal or a reproduction clock signal for detecting the relative position between the head and the data track is provided. Preformat information corresponding to one data track is recorded at constant angular intervals concentrically with the data track, and the entire magnetic recording medium has a fan-shaped preformat information provided at regular angular intervals. It is recorded in the (format) preformat area.

  In order to prevent the center of the preformat signal from decentering from the center of the magnetic recording medium or the center of the track of the data recording / reproducing head, the preformat information is stored in a dedicated track called a servo track writer after the magnetic recording medium is installed in the HDD It has been recorded using a writing device.

  On the other hand, as the recording density increases in response to the demand for higher density magnetic recording media, the recording density of the preformat information inevitably increases, and the time for writing the preformat information increases. As a result, it has become an urgent factor that causes a decrease in HDD production efficiency and an increase in cost.

  In recent years, instead of writing a line for each track by a signal writing head of a servo track writer, a method has been proposed in which a master disk carrying preformat information is used, and preformat information is written on a magnetic recording medium by magnetic transfer technology. For example, by using a master disk having a concavo-convex shape, the convex part of which is made of a ferromagnetic material, the preformat information is transferred to a longitudinal magnetic recording medium (slave disk). A method is disclosed. (For example, refer to Patent Document 1.)

JP 10-40544 A Japanese Patent Laid-Open No. 2005-50477

  In the mass production process, in order to apply the above magnetic transfer technology, transfer of contaminants from the slave disk surface to the master disk surface, especially the liquid lubricant applied to the slave disk surface moves to the master disk surface. However, contamination of the master disk surface is a big problem. When such a process is repeated many times, if the preformatting of the magnetic recording medium (slave disk) on which the preformat information is magnetically transferred, the corners of the information recording area may be disturbed or the recording may be lost. Because of this, it has been difficult to record a large number of sheets.

  Patent Document 2 proposes to apply a lubricant that can be diluted with a soluble solvent, which is different from the lubricant used for the slave disk, to the master disk. The lubricant can be easily removed by wiping even if it is transferred.

  However, in Patent Document 2, the wiping process is performed using different types of lubricants for the slave carrier and the master carrier. In this document, it is assumed that lubricant adheres from the slave to the master, but in reality, the possibility of lubricant adherence from the master to the slave cannot be denied. Is not mentioned. According to the present invention, there is no need to use a liquid lubricant on the master surface, and the adhesion phenomenon from the master disk to the slave disk, which is concerned by the above phenomenon, does not occur.

  The problem to be solved by the present invention is to solve the above problems, suppress the transfer of the lubricant from the slave disk to the master disk, and stabilize the surface state of the slave disk by changing the servo recording signal transfer. Thus, the magnetic transfer can be stably performed many times.

  That is, the master disk of the present invention has a pattern corresponding to the preformat information on the surface of the nonmagnetic substrate and the nonmagnetic substrate, or a plurality of soft magnetic layers isolated from each other, A master disk for magnetically transferring preformat information to a magnetic recording layer on the surface of a magnetic recording medium, having a protective layer on the surface, and having a fluorination treatment on the surface of the protective layer It is characterized by.

  According to the present invention, by performing fluorination treatment on the surface of the master disk, it is possible to reduce the surface energy on the master disk and suppress the adhesion amount of the lubricant. As a result, lubricant transfer from the slave disk side to the master disk side can be suppressed, and the magnetic transfer of the servo recording signal from the master disk to the slave disk can be stably performed many times.

It is a figure which shows the master disk production process in the Example of this invention. It is a figure which shows the close_contact | adherence state of the master disk in the Example of this invention, and a slave disk. It is a figure which shows the magnetic transfer process in the Example of this invention. It is a figure which shows the difference in the lubricant amount on the master disk after a transfer process by the presence or absence of a fluorination process. It is a figure which shows the relationship between the lubricant quantity on the master disk after the transfer process in the Example of this invention, and the number of transfer processes. It is a figure which shows the relationship between the lubricant amount on the master disk after a transfer process, and the surface composition ratio F / C of the carbon of a master disk, and a fluorine.

  The master disk of the present invention has a nonmagnetic substrate and a pattern corresponding to preformat information on the surface of the nonmagnetic substrate or on the surface portion. As the nonmagnetic substrate, various glass substrates conventionally used as substrates for magnetic disks and optical disks, plastic substrates such as polycarbonate, metal substrates such as Al alloys, and the like are used.

  FIG. 1 is a schematic diagram showing an example of a master disk manufacturing process. As shown in FIG. 1E, the master disk has a plurality of isolated protrusions made of soft magnetic material in a predetermined pattern on a non-magnetic substrate 4. A portion (soft magnetic layer) 3 'is formed, and a protective layer is formed so as to cover the nonmagnetic substrate 1 and the convex portion 3' made of a soft magnetic material. This soft magnetic layer is composed of a plurality of isolated protrusions formed in a line-shaped periodic region.

  As the soft magnetic material, for example, crystalline NiFe alloy, Sendust (FeSiAl) alloy, CoFe alloy, or the like, microcrystalline FeTaC, CoFeNi, CoNiP, or the like can be used.

  As the protective layer, a conventionally used protective film can be used, but a protective layer mainly composed of carbon is preferably used. A diamond-like carbon layer is preferably used as the protective layer mainly composed of carbon.

  The surface of this protective layer has been subjected to fluorine processing. The method for manufacturing the master disk, including the fluorine processing, will be described with reference to FIG.

First, the soft magnetic layer 3 is formed on the nonmagnetic substrate 4, and then the mask layer 2 used as a mask when the soft magnetic layer is etched is formed by sputtering. After the film formation up to the mask layer 2, a resist layer 1 used for patterning the mask layer 2 is formed (FIG. 1A). As a material for forming the mask layer 2, any material can be used as long as it is a material used for a mask for etching a soft magnetic layer, such as a carbon film, a SiO ₂ film, and a Ti film.

  After forming the resist layer 1, a desired pattern is formed on the resist layer 1 by a nanoimprint process (FIG. 1B). The nanoimprint process is a step of transferring the concavo-convex shape engraved in the mold 5 to the resist layer 1 by pressing the mold 5 engraved with the concavo-convex pattern against the surface on which the resist layer 1 is formed. The nanoimprint includes thermal nanoimprint and optical nanoimprint. In the former case, a thermoplastic resin is used for the resist layer 1, and in the latter case, a photocurable resin is used. When the resist layer 1 is a thermoplastic resin or a thermosetting resin, any resin can be used as long as it is a resin that is usually used as a resist for nanoimprinting.

Patterning of the mask layer 2 is performed by the uneven pattern of the resist layer 1 formed by nanoimprinting. Here, when a carbon film is used for the mask layer 2, the mask layer 2 can be patterned using reactive ion etching using O ₂ as a reactive gas (FIG. 1C).

  After the mask layer 2 is patterned, the soft magnetic layer 3 can be patterned by ion beam etching using the mask layer 2 (FIG. 1D). In this case, a gas in which the mask layer 2 is difficult to be etched is used as the atmospheric gas during the ion beam etching. For example, when the mask layer is made of carbon, Ar gas can be used as the atmospheric gas.

  Thereafter, the remaining mask layer 2 is removed by reactive ion etching, and then the protective layer 6 is formed by sputtering (FIG. 1 (e)). The reactive gas used in the mask layer etching may be the same gas as the reactive gas used in patterning the mask layer.

  The protective layer 6 is preferably made of diamond-like carbon having a thickness of 3 to 30 nm.

  The master disk manufactured by the above process can be fluorinated using an ion beam etching method.

  Although fluorine adheres to the surface of the carbon protective layer 6 that has been subjected to the fluorination treatment, the surface composition ratio F / C of fluorine and carbon on the surface of the protective layer 6 is preferably 0.25 or more, and 0.4 or more It is more preferable that

  The magnetic transfer of the preformat information of the master disk 8 to the magnetic recording layer on the surface of the magnetic recording medium (slave disk) 9 brings the master disk 8 into close contact with one surface or both surfaces of the magnetic recording medium 9 ( 2), after the magnetic recording medium is brought into close contact, a magnetic field is applied in the longitudinal direction. FIG. 2 shows an example in which the master disk 8 is brought into close contact with one surface of the magnetic recording medium 9.

  The surface of the magnetic recording medium (slave disk) 9 is covered with a lubricant, more specifically a fluorine-based lubricant. The recording and writing of data on the magnetic recording medium and the sliding with the magnetic head during the call are lubricated and damaged. Prevent the occurrence of

  As a magnetic head for applying a magnetic field in the longitudinal direction, a ring head 10 in which a yoke is attached to a permanent magnet as shown in FIG. 3 is used. A gap is formed at the tip of the yoke of the ring head 10, and the gap is used so as to face the master disk. In general, the same two ring heads 10 are arranged so as to face each other with the disks (master disk 8 and slave disk 9) as the center (FIG. 3). The magnetic transfer is performed by moving the ring head 10 to a portion where the magnetic layer pattern of the master disk 9 is transferred. After the magnetic transfer, the master disk 8 and the magnetic recording medium 9 are released, and the magnetic transfer process is completed.

  The present invention will be further described below with reference to examples.

<Example 1>
A master disk 8 based on the present invention was manufactured and a verification experiment was performed.

  First, a soft magnetic layer 3 made of CoFeNi was formed on a nonmagnetic substrate 4 made of glass, and then a mask layer 2 made of carbon was formed by sputtering. Next, SOG (Spin On Glass) was used as a resist to form a resist layer 1, and then a desired pattern was formed on the resist layer 1 by a nanoimprint process (FIG. 1B).

Subsequently, the mask layer 2 was patterned by the uneven pattern of the resist layer 1 formed by nanoimprinting. That is, patterning of the mask layer 2 was performed using reactive ion etching using O ₂ as a reactive gas (FIG. 1C).

  Next, after patterning the mask layer 2, the mask layer 2 was used to pattern the soft magnetic layer 3 by ion beam etching using Ar gas (FIG. 1D).

Thereafter, the remaining mask layer was removed by reactive ion etching using O ₂ as a reactive gas, and then a 5 nm thick protective layer 6 made of diamond-like carbon was formed by sputtering (FIG. 1 (e)).

The master disk thus obtained was fluorinated using an ion beam etching method. That is, using a high-density plasma etching apparatus NE-550 manufactured by ULVAC, using CF ₄ as a reactive gas, a flow rate of 40 sccm, an RF power of 200 W, a pressure of 1.5 Pa, and a processing time of 60 seconds by an ion etching method. The surface of the protective layer 6 was fluorinated.

  The surface fluorinated master disk 8 and the magnetic recording medium (slave disk) 9 coated with Z-tetraol (manufactured by Solvay Solexis), which is a fluorine-based lubricant, are brought into close contact with each other, and then in the longitudinal direction. Magnetic transfer was performed by applying a magnetic field. As a magnetic head for applying a magnetic field in the longitudinal direction, two ring heads 10 each having a yoke attached to a permanent magnet as shown in FIG. 3 are used and arranged so as to face each other with the disk as the center. Magnetic transfer was performed by moving the magnetic layer pattern of the disk 8 to the transfer site. A gap is formed at the tip of the yoke of the ring head, and the gap is used so as to face the master disk 8. After the magnetic transfer, the master disk 8 and the magnetic recording medium 9 were released.

  FIG. 4 shows the result of measuring the thickness of the lubricating layer attached to the master disk 8 that has undergone the magnetic transfer process with the slave disk 9 (lubricant film thickness 1.0 nm). It can be seen that by performing fluorination treatment, the transfer amount of the lubricant can be reduced to 1/4 or less and the transfer amount can be suppressed to 0.05 nm or less as compared with the master disk without surface treatment.

  FIG. 5 shows the transition of the lubricant film thickness on the master disk when the transfer process is repeated. It can be seen that the transfer of the lubricant from the slave disk to the master disk is almost saturated by the transfer of 5 times or more, and the film thickness change of 0.1 nm or less can be suppressed even when accumulated.

  Next, FIG. 6 shows the relationship between the surface composition ratio F / C of carbon and fluorine on the master disk surface by the fluorination treatment, and the lubricating layer thickness attached to the master disk that has undergone the magnetic transfer process. The fluorination treatment amount was adjusted by adjusting the treatment time of the ion etching method, and the surface composition ratio F / C was measured by ESCA (Electron Spectroscopy for Chemical Analysis: Quantera SXM manufactured by ULVAC-PHI).

  From the results shown in FIG. 6, if the transfer amount is suppressed to 0.1 nm or less, the surface composition ratio F / C is 0.25 or more, and more desirably, the transfer amount is suppressed to 0.05 nm or less. It can be seen that the composition ratio F / C should be 0.4 or more.

1. Resist layer 2. Mask layer Soft magnetic layer 3 '. 3. Soft magnetic layer (convex part) 4. Non-magnetic substrate Mold 6. Protective layer 7. Servo area 8. Master disk 9. Magnetic recording medium 10. Ring head

Claims (4)

  The preformat information on the surface of the magnetic recording medium has a pattern corresponding to the preformat information on the surface of the nonmagnetic substrate and the nonmagnetic substrate, or a plurality of soft magnetic layers isolated from each other. A master disk for magnetically transferring to a magnetic recording layer, wherein the master disk has a protective layer on the surface, and a fluorination treatment is applied to the surface of the protective layer.   The master disk according to claim 1, wherein the protective layer is a diamond-like carbon layer having a thickness of 3 to 30 nm.   The master disk according to claim 1 or 2, wherein the surface composition ratio F / C of fluorine and carbon on the surface of the protective layer subjected to the fluorination treatment is 0.25 or more.   The master disk according to claim 3, wherein a surface composition ratio F / C of fluorine and carbon on the surface of the protective layer subjected to the fluorination treatment is 0.4 or more.

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