JP2009245544A - Master carrier for magnetic transfer, magnetic transfer method, and magnetic recording medium - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a master carrier for magnetic transfer having a magnetic layer which is initially magnetized to increase the magnetic permeability (B/H), and the like. <P>SOLUTION: The magnetic transfer master carrier 20 includes a substrate 200 having, on a surface thereof, protruding portions 201 arranged corresponding to a pattern of information to be recorded onto a perpendicular magnetic recording medium, and the magnetic layer 40 having perpendicular magnetic anisotropy formed on at least end surfaces 202 of the protruding portions 201. In the magnetic transfer master carrier 20, when a recording magnetic field is applied, the magnetic layer 40 absorbs magnetic flux to form a pattern of magnetic field. An initial magnetic field having a coercive force of Hc or more is applied in advance to the magnetic layer 40 in the same direction as that in which the recording magnetic field is applied. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a magnetic transfer master carrier for magnetically transferring information to a magnetic recording medium, a magnetic transfer method using the magnetic transfer master carrier, and a magnetic recording medium magnetically transferred using the magnetic transfer master carrier.

 As a magnetic recording medium capable of recording information at a high density, a magnetic recording medium of a perpendicular magnetic recording system (hereinafter referred to as a perpendicular magnetic recording medium) is known. The information recording area of this perpendicular magnetic recording medium is composed of narrow tracks. Therefore, in a perpendicular magnetic recording medium, a tracking servo technique for accurately scanning a magnetic head in a narrow track width and reproducing a signal with a high S / N ratio is important. In order to perform this tracking servo, it is necessary to record servo information such as a tracking servo signal, an address information signal, and a reproduction clock signal in a so-called preformat on a perpendicular magnetic recording medium at predetermined intervals.

  As a method for preformatting servo information on a perpendicular magnetic recording medium, for example, a master carrier on which a pattern consisting of a plurality of convex portions having a magnetic layer on the surface corresponding to the servo information is formed is used. There is a method in which a recording magnetic field is applied in a state of being in close contact with the magnetic recording medium, and servo information corresponding to the pattern of the master carrier is magnetically transferred to the perpendicular magnetic recording medium (see, for example, Patent Documents 1 to 3).

  In the method, when a recording magnetic field is applied in a state where the master carrier is in close contact with a perpendicular magnetic recording medium, magnetic flux is absorbed by the magnetic layer arranged in a pattern based on the magnetization state of the master carrier. . As a result, the recording magnetic field is strengthened corresponding to the pattern of the master carrier. Only a predetermined portion of the perpendicular magnetic recording medium is magnetized by the magnetic field strengthened in the pattern. In this way, servo information corresponding to the pattern of the master carrier is magnetically transferred to the perpendicular magnetic recording medium.

  In order to perform high-density magnetic transfer with high signal quality using the master carrier, it is sufficient to reverse the magnetization of the medium at the convex portion having the magnetic layer of the master carrier. It is necessary to generate a magnetic field and to generate a weak magnetic field that can be maintained in an initial magnetization state as much as possible so as not to reverse the magnetization of the medium in the concave portion between the convex portions. It is also necessary to increase the contrast between the magnetic field of the convex portion and the magnetic field of the concave portion.

  Therefore, it is preferable that the magnetic layer of the convex portion of the master carrier can obtain a high magnetization amount with a weak applied magnetic field.

  In view of the above circumstances, a magnetic layer of the master carrier is required that can obtain high magnetization with a weak applied magnetic field.

JP 2003-203325 A JP 2000-195048 A U.S. Pat. No. 7,218,465

  An object of the present invention is to solve the above-described problems and achieve the following objects. That is, the present invention provides a magnetic transfer master carrier having a magnetic layer that is initially magnetized and has an increased B / H, a magnetic transfer method using the magnetic transfer master carrier, and the magnetic transfer master carrier. An object of the present invention is to provide a manufactured magnetic recording medium.

Means for solving the above problems are as follows. That is,
<1> A substrate having convex portions disposed on the surface corresponding to a pattern of information to be recorded on the perpendicular magnetic recording medium, and having perpendicular magnetic anisotropy formed at least on a tip surface of the convex portion. A magnetic transfer master carrier that absorbs a magnetic flux to form a magnetic field pattern when a recording magnetic field is applied to the magnetic layer, wherein the magnetic layer includes the magnetic field for recording. The magnetic transfer master carrier is characterized in that an initialization magnetic field having a coercive force Hc or more is applied in advance from the same direction as the direction in which is applied.
In the magnetic transfer master carrier according to <1>, the magnetic layer has the same strength by applying an initializing magnetic field equal to or greater than the coercive force Hc in advance from the same direction as the direction in which the recording magnetic field is applied. The value of B (magnetic flux density) when a magnetic field is applied increases.
<2> The magnetic transfer master carrier according to <1>, wherein the initialization magnetic field is equal to or higher than a saturation magnetic field Hs.
<3> An initial magnetization step for initial magnetization of a perpendicular magnetic recording medium by applying a magnetic field, and the magnetic transfer master carrier described in <1> or <2> in close contact with the initially magnetized perpendicular magnetic recording medium And applying a recording magnetic field opposite to the magnetic field applied in the initial magnetization step to the perpendicular magnetic recording medium in a state where the perpendicular magnetic recording medium and the magnetic transfer master carrier are in close contact with each other. And a magnetic transfer process for recording information.
<4> A magnetic recording medium produced using the magnetic transfer method according to <3>.
<5> A substrate having a convex portion disposed on the surface corresponding to a pattern of information to be recorded on the perpendicular magnetic recording medium, and has a perpendicular magnetic anisotropy formed at least on a tip surface of the convex portion. An initial magnetization method of a magnetic transfer master carrier in which a magnetic field pattern is formed based on the arrangement of the magnetic layer when a recording magnetic field is applied to the magnetic layer. An initial magnetization method for a master carrier for magnetic transfer, wherein an initialization magnetic field having a coercive force Hc or more is applied in advance from the same direction as the direction in which the recording magnetic field is applied.
<6> The method for initial magnetization of a master carrier for magnetic transfer according to <5>, wherein the initialization magnetic field is equal to or greater than the saturation magnetic field Hs.

  According to the present invention, the above conventional problems can be solved, and a magnetic transfer master carrier having a magnetic layer that has been initially magnetized and has an increased B / H, and a magnetic transfer method using the magnetic transfer master carrier And a magnetic recording medium produced using the magnetic transfer master carrier.

  Hereinafter, a master carrier for magnetic transfer, a magnetic transfer method, and a magnetic recording medium according to an embodiment of the present invention will be described with reference to the drawings.

  FIG. 1 is an explanatory diagram showing an outline of a magnetic transfer method in which information is magnetically transferred to a perpendicular magnetic recording medium using a magnetic transfer master carrier. The magnetic transfer method includes an initial magnetization process, an adhesion process, and a magnetic transfer process. First, an outline of a magnetic transfer technique using the magnetic transfer master carrier will be described with reference to FIG.

[Outline of magnetic transfer technology]
In FIG. 1, reference numeral 10 represents a slave disk that is a perpendicular magnetic recording medium, and reference numeral 20 represents a master disk that is a master carrier for magnetic transfer.
FIG. 1A is an explanatory diagram showing an initial magnetization process. As shown in FIG. 1A, in the initial magnetization step, a DC magnetic field (Hi) is applied to the slave disk 10 so that the slave disk 10 is initially magnetized. The DC magnetic field (Hi) is applied perpendicular to the plane of the slave disk 10.
FIG.1 (b) is explanatory drawing which shows a contact | adherence process. As shown in FIG. 1B, in the adhesion step, the master disk 20 is adhered to the slave disk 10 after the initial magnetization.
FIG. 1C is an explanatory diagram showing a magnetic transfer process. As shown in FIG. 1C, in the magnetic transfer step, a magnetic field (Hd) (recording magnetic field) opposite to the DC magnetic field (Hi) is applied to the slave disk 10 and the master disk 20 that are in close contact with each other. When applied, information based on the master disk 20 is recorded on the slave disk 10.

  Next, the magnetic transfer master carrier, the magnetic transfer method, and the magnetic recording medium will be described in detail with reference to the drawings.

[Master carrier for magnetic transfer]
FIG. 2 is an explanatory diagram showing an outline of a cross section of the magnetic transfer master carrier (master disk) 20. As shown in FIG. 2, the magnetic transfer master carrier 20 includes a substrate 200 and a magnetic layer 40.

(Base material)
There is no restriction | limiting in particular as a material of the said board | substrate 200, Although it can select suitably according to the objective, For example, well-known materials, such as synthetic resins, such as glass and a polycarbonate, metals, such as nickel and aluminum, silicon, and carbon, are used. .

  There is no restriction | limiting in particular as a shape of the said board | substrate 200, According to the objective, it can select suitably. The magnetic transfer master carrier 20 shown in FIG. 2 has a disk shape. The substrate 200 has a plurality of convex portions 201 on the surface.

  The convex portion 201 is disposed on the surface of the substrate 200 corresponding to the pattern of information to be recorded on the perpendicular magnetic recording medium. Examples of information to be recorded on the perpendicular magnetic recording medium include servo information for tracking servo technology such as a servo signal and an address information signal. The convex portion 201 forms a pattern corresponding to the pattern of information to be recorded on the surface of the substrate 200. There is no restriction | limiting in particular as the number of this convex part 201 arrange | positioned on the surface of the said board | substrate 200, According to the objective, it can select suitably.

  FIG. 3 is an explanatory view of the magnetic transfer master carrier 20 (master disk) as viewed from above. As shown in FIG. 3, on the surface (upper surface) of the master carrier 20 for magnetic transfer, a pattern (servo pattern 52) composed of convex portions arranged corresponding to the servo information pattern is formed radially. ing.

  As shown in FIG. 2, the surface of the convex portion 201 includes a front end surface 202 and a side surface 203. In the present embodiment, the tip surface 202 is a flat surface. The outer shape of the distal end surface 202 is not particularly limited and can be appropriately selected depending on the purpose. In the present embodiment, the distal end surface 202 is a quadrangle (square). There is a recess 204 between the protrusions 201.

(Magnetic layer)
The magnetic layer 40 is formed on at least the front end surface 202 of the surface of the convex portion 201. As shown in FIG. 2, in the present embodiment, the magnetic layer 400 is also formed on the surface of the concave portion 204 for reasons such as easy manufacture, in addition to the tip surface 202 of the convex portion 201.

The magnetic layer 40 includes a magnetic material having perpendicular magnetic anisotropy. The magnetic material of the magnetic layer 40 includes at least one ferromagnetic metal of Fe, _CO, and Ni, and at least one nonmagnetic of Cr, Pt, Ru, Pd, Si, Ti, B, Ta, and O. An alloy or a compound composed of a substance is used.
The magnetic layer 40 has magnetic anisotropy in a direction perpendicular to the in-plane direction of the magnetic layer 40.

There is no restriction | limiting in particular as thickness of the said magnetic layer 40, Although it sets suitably according to the objective, 5 nm-100 nm are preferable, 10 nm-60 nm are more preferable, 20 nm-40 nm are still more preferable.
When the thickness of the magnetic layer 40 is less than 5 nm, the transfer magnetic field generated from the convex portion of the pattern may be insufficient, and when the thickness exceeds 100 nm, the transfer magnetic field diverges due to the deterioration of the pattern convex portion shape, There are cases where writing of signals along the target pattern is not possible.

  The thickness of the magnetic layer 40 can be measured by, for example, a transmission electron microscope (TEM). The thickness of the magnetic layer 40 is an average thickness at three locations measured by length measurement from a transmission electron microscope (TEM) (see FIG. 4). As shown in FIG. 4, three measured points (6a, 6b, and 6c (the center portion (6a) of the tip surface of the convex portion 201 and two end portions facing the center portion therebetween ( Edge) (6b and 6c).

  As a method for forming the magnetic layer 40 (film formation method), for example, there is a sputtering method. The magnetic layer 40 can be formed by a sputtering method by appropriately selecting conditions such as the deposition pressure (Pa), the substrate-target distance (mm), and the DC power (W).

  When the magnetic layer 40 is made of CoPt, the perpendicular magnetic anisotropy of the magnetic layer 40 can be controlled mainly by adjusting the type of the underlayer (underlayer).

  In the present specification, “the magnetic layer 40 has“ perpendicular magnetic anisotropy ”means that the magnetization value (Min) of the in-plane magnetization curve and the magnetization value (Mpe) of the perpendicular magnetization curve, which are obtained by the following methods. This is a case where the ratio (Mpe / Min) of (Mpe / Min)> 1. The method for obtaining Min and Mpe is as follows.

The same magnetic layer 40 of the magnetic transfer master carrier is formed on a glass substrate (2.5 inches) under the same conditions as in the production of the master carrier. A sample formed on the glass substrate was cut into a size of 6 mm × 8 mm, and the cut sample was subjected to in-plane direction and vibration sample magnetometer (VSM-C7, manufactured by Toei Kogyo Co., Ltd.). A magnetic field is applied in the vertical direction, and the magnetization curve of the sample is measured.
Based on the obtained magnetization curve, the magnetization value (Min) of the in-plane magnetization curve and the magnetization value (Mpe) of the perpendicular magnetization curve at the externally applied magnetic field strength equivalent to the recording magnetic field are calculated.

(Underlayer)
An underlayer may be formed under the magnetic layer 40 as necessary. Examples of the material for the underlayer include metals, alloys, and compounds containing at least one of Pt, Ru, Pd, Co, Cr, Ni, W, Ta, Al, P, Si, and Ti. The material for the underlayer is preferably a white metal such as Pt or Ru, or an alloy. The underlayer may be a single layer or a multilayer. The underlayer can be formed by a known method such as a sputtering method.
The thickness of the underlayer is preferably in the range of 1 nm to 30 nm, and more preferably in the range of 5 nm to 20 nm.

(Protective layer, etc.)
A protective layer such as diamond-like carbon may be formed on the magnetic layer 40 as necessary. The thickness of the protective layer is usually 10 nm or less. Furthermore, a lubricant layer may be formed on the protective layer.

(Initial magnetization of magnetic layer)
The magnetic layer 40 is initially magnetized. The initial magnetization is caused by applying an initializing magnetic field to the magnetic transfer master carrier 20 having the magnetic layer 40 in the same direction as the recording magnetic field (Hd) application direction (see FIG. 1C) in the magnetic transfer process. This is done by applying.
The strength of the initialization magnetic field is preferably not less than the coercive force Hc of the magnetic layer 40, and particularly preferably not less than the saturation magnetic field Hs of the magnetic layer 40.
If the strength of the initialization magnetic field is less than the coercive force Hc of the magnetic layer 40, sufficient residual magnetization cannot be obtained, and the value of B / H may not increase.
Incidentally, the coercive force Hc and the saturation magnetic field Hs in this specification are those obtained by measuring a magnetic layer formed on a Ni substrate under the condition of a sweep speed of 20,000 Oe / 100 s.

  FIG. 5 is an explanatory diagram showing BH curves of the magnetic layer before and after initial magnetization. The horizontal axis shown in FIG. 5 represents the externally applied magnetic field H, and the vertical axis represents the magnetic flux density B of the magnetic layer. Hc in FIG. 5 represents the coercivity of the magnetic layer, and Hs represents the saturation magnetic field of the magnetic layer. Ha represents the recording magnetization (Hd) applied in the magnetic transfer process. In FIG. 5, the section indicated by the arrow a represents the BH curve of the magnetic layer before the initial magnetization, and the section indicated by the reference b represents the BH curve of the magnetic layer after the initial magnetization. Represents. The initial magnetization of the magnetic layer is performed by applying an initialization magnetic field that is equal to or higher than the saturation magnetic field Hs.

  As shown in FIG. 5, when comparing the magnetization amount with respect to the same external magnetic field (applied magnetic field) H, the magnetization amount (B / H) with respect to the applied magnetic field after the initial magnetization is larger than the magnetization amount with respect to the applied magnetic field before the initial magnetization. It is getting bigger. When the externally applied magnetic field H is zero, the magnetic layer after the initial magnetization has a higher magnetic flux density than the magnetic layer before the initialization. That is, the residual magnetization of the magnetic layer is increased by the initial magnetization.

Thus, by magnetically initializing the magnetic layer, a magnetic layer having a BH curve that increases B / H can be obtained.
Therefore, the magnetic layer after the initial magnetization can obtain a higher magnetic flux density with a smaller external magnetic field than the magnetic layer before the initial magnetization.

If the residual magnetic flux density (residual magnetization) of the magnetic layer is too high, the magnetic recording master carrier is separated from the perpendicular magnetic recording medium after the magnetic transfer is completed. The medium may be magnetized unnecessarily.
Therefore, it is necessary to appropriately select the composition of the magnetic layer and the strength of the initial magnetization magnetic field of the magnetic layer so that the perpendicular magnetic recording medium is not recorded by the residual magnetization of the magnetic layer.

[Method of manufacturing master carrier for magnetic transfer]
A master is used to manufacture the magnetic transfer master carrier 20. First, one manufacturing method of the master will be described with reference to FIG.

(Manufacture of master)
FIG. 6 is an explanatory view showing a manufacturing process of a master used for manufacturing the magnetic transfer master carrier 20.
As shown in FIG. 6A, an original plate 30 made of a silicon wafer (Si substrate) having a smooth surface is prepared, and an electron beam resist solution is applied onto the original plate 30 by a spin coating method or the like. The layer 32 is formed (see FIG. 6B). Thereafter, the resist layer 32 is baked (pre-baked).

  Next, as shown in FIG. 6C, the original plate 30 is set on a stage of an electron beam exposure apparatus (not shown) provided with a high-precision rotary stage or an XY stage, While rotating, the resist layer 32 was irradiated with an electron beam modulated in accordance with a servo signal, and a pattern corresponding to the servo signal was drawn and exposed on the resist layer 32. In FIG. 6C, reference numeral 33 represents an exposed portion.

Next, as shown in FIG. 6D, when the resist layer 32 is developed and the exposed portion (drawing portion) 33 is removed, a patterned resist layer 32 is formed on the original plate 30.
The resist applied on the original plate 30 can be either a positive type or a negative type. Note that the exposure (drawing) pattern is reversed between the positive type and the negative type.
After the development process, a baking process (post-bake) for increasing the adhesion between the resist layer 32 and the original plate 30 is performed.

  Next, as shown in FIG. 6E, the original plate 30 is removed (etched) from the surface by a predetermined depth from the opening 34 of the resist layer 32 using the resist layer 32 as a mask. As the etching, it is preferable to select anisotropic etching in order to minimize undercut (side etching). As the anisotropic etching, reactive ion etching (RIE) is preferable.

  Next, as shown in FIG. 6F, the etched resist layer 32 is removed. As a method for removing the resist layer 32, any of a dry method such as ashing and a wet method such as removal with a stripping solution can be employed. When the resist layer 32 is removed, a master disk 36 is obtained.

(Manufacture of master carrier for magnetic transfer)
A method for manufacturing the magnetic transfer master carrier 20 using the master 36 will be described with reference to FIG.

  As shown in FIG. 7G, a conductive layer 37 having a uniform thickness is formed on the surface of the master disc 36. As a method for forming the conductive layer 37, various metal film forming methods such as PVD (Physical Vapor Deposition), CVD (Chemical Vapor Deposition), sputtering, and ion plating can be employed. The conductive layer 37 is made of a film containing Ni as a main component, for example. Such a film containing Ni as a main component is suitable for the conductive film 37 because it is easy to form and is hard. The thickness of the conductive layer 37 is not particularly limited and may be appropriately selected depending on the intended purpose, but is generally about several tens of nm.

Next, as shown in FIG. 7H, a metal plate 38 having a desired thickness is laminated on the surface of the master 36 by electroforming. Examples of the material of the metal plate include Ni.
Electroforming is performed in a predetermined electroforming apparatus (not shown). The electrolytic apparatus has an electrolytic solution tank containing an electrolytic solution such as Ni sulfamate, and the master 36 is immersed in the electrolytic solution in the electrolytic solution tank. When the master 36 is used as an anode, and a current is passed between the anode and a cathode (not shown), a metal plate is laminated on the master 36. Various conditions such as the concentration of the electrolytic solution, the pH of the electrolytic solution, and the current value are appropriately set.
Thereafter, the master 36 on which the metal plate 38 is laminated is taken out from the electrolytic bath of the electroforming apparatus and immersed in a stripping solution made of pure water or the like. In the stripping solution, the metal plate 38 is peeled off from the master 36. In this way, a substrate 200 having a surface shape in which the uneven shape on the surface of the master disk 36 is inverted as shown in FIG.

  Next, as shown in FIG. 7J, the magnetic layer 40 is formed on the tip surface 202 of the convex portion 201 on the surface of the substrate 200. The material of the magnetic layer 40 is made of, for example, CoPt. The magnetic layer 40 is formed by a sputtering method using the material as a target.

Next, as shown in FIG. 7 (k), an initializing magnetic field H is applied to the magnetic layer 40 to perform initial magnetization of the magnetic layer 40.
Thereafter, if necessary, the master substrate 20 for magnetic transfer is obtained by punching the substrate 200 into a predetermined size.

[Perpendicular magnetic recording medium]
The perpendicular magnetic recording medium that is magnetically transferred using the magnetic transfer master carrier 20 is not particularly limited and may be appropriately selected depending on the intended purpose. FIG. 8 is an explanatory diagram showing an outline of a cross section of a perpendicular magnetic recording medium. Here, the configuration of the perpendicular magnetic recording medium according to an embodiment will be described with reference to FIG.

  As shown in FIG. 8, the perpendicular magnetic recording medium 10 includes a substrate 12, a soft magnetic layer (soft magnetic underlayer: SUL) 13, a nonmagnetic layer (intermediate layer) 14, and a magnetic layer 15. Have. Further, the perpendicular magnetic recording medium 10 shown in FIG. 7 includes a protective layer 16 and a lubricant layer 17 on the magnetic layer 16.

  The substrate 12 has a disk shape and is made of a nonmagnetic material such as glass or Al (aluminum).

  The soft magnetic layer 13 is provided for the purpose of stabilizing the perpendicular magnetization state of the magnetic layer 16 and improving the sensitivity during recording and reproduction. As the material used for the soft magnetic layer 13, soft magnetic materials such as CoZrNb, FeTaC, FeZrN, FeSi alloy, FeAl alloy, FeNi alloy such as permalloy, and FeCo alloy such as permendur are used. The soft magnetic layer 13 has a magnetic anisotropy in a radial direction (radially) from the center of the disk to the outside.

  The nonmagnetic layer 14 is provided for the purpose of increasing the perpendicular magnetic anisotropy of the magnetic layer 15 to be formed later. As the material used for the nonmagnetic layer 14, Ti, Cr, CrTi, CoCr, CrTa, CrMo, NiAl, Ru, Pd, Ta, Pt, or the like is used.

The magnetic layer 15 is made of a perpendicular magnetization film. In the perpendicular magnetization film, the easy axis of magnetization in the film is oriented mainly in the perpendicular direction with respect to the substrate 12. Information is recorded on the magnetic layer 15.
Examples of materials used for the magnetic layer 15 include Co alloys (CoPtCr, CoCr, CoPtCrTa, CoPtCrNbTa, CoCrB, CoPt, CoPtCrO, CoPtCr—SiO ₂ , CoPtCr—TiO ₂ , CoPt—SiO ₂ , CoPt—TiO _2, etc.) Fe, an Fe alloy (FeCo, FePt, FeCoNi, etc.) or the like is used.

  The protective layer 16 is made of C (carbon) or the like, and the lubricant layer 17 is made of a fluorine-based lubricant such as PFPE.

In the perpendicular magnetic recording medium 10, the magnetic layer 15 is formed on one surface of the substrate 12. However, in other embodiments, the magnetic layer 15 may be formed on the front and back surfaces of the substrate 12.
In another embodiment, a plurality of soft magnetic layers 13 and nonmagnetic layers 14 may be formed.

[Magnetic transfer method]
Hereinafter, a method for magnetically transferring information to the perpendicular magnetic recording medium using the magnetic transfer master carrier will be described.
As described in the outline of the magnetic transfer technique, the magnetic transfer method includes an initialization process, an adhesion process, and a magnetic transfer process. Hereinafter, a magnetic transfer method according to an embodiment will be described with reference to FIG.

<Initial magnetization process>
The initialization step is a step of initializing the perpendicular magnetic recording medium 10 by applying a DC magnetic field (Hi) to the perpendicular magnetic recording medium 10 (slave disk).
As shown in FIG. 1A, a DC magnetic field (Hi) is applied to the perpendicular magnetic recording medium 10 in the initial magnetization step. The DC magnetic field (initializing magnetic field) (Hi) is applied perpendicularly to the surface of the perpendicular magnetic recording medium 10. The DC magnetic field (Hi) is applied by a predetermined magnetic field applying means (not shown). The strength of the DC magnetic field (Hi) is set to be equal to or greater than the coercive force of the perpendicular magnetic recording medium 10.

  FIG. 9 is an explanatory diagram showing the magnetization direction of the magnetic layer of the perpendicular magnetic recording medium after the initial magnetization. As shown in FIG. 9, the magnetic layer 15 of the perpendicular magnetic recording medium 10 after the initial magnetization is initially magnetized in one direction perpendicular to the disk surface of the perpendicular magnetic recording medium 10. In addition, the arrow shown with the code | symbol Pi in FIG. 9 represents the magnetization direction of this magnetic layer.

<Adhesion process>
In the adhesion step, the magnetic transfer master carrier (on the perpendicular magnetic recording medium 10 after the initial magnetization)
This is a step of bringing the master disk) 20 into close contact.
As shown in FIG. 1B, the perpendicular magnetic recording medium 10 after initial magnetization and the master carrier 20 for magnetic transfer are superposed and brought into close contact with each other.
In the adhesion step, the magnetic layer 40 on the convex portion 201 on the surface of the magnetic transfer master carrier 20 and the magnetic layer (recording layer) of the perpendicular magnetic recording medium 10 are adhered to each other. The magnetic transfer master carrier 20 is brought into close contact with the perpendicular magnetic recording medium 10 with a predetermined pressing force.

  If necessary, before the magnetic transfer master carrier 20 is brought into intimate contact with the perpendicular magnetic recording medium 10, fine projections or adhering dust on the surface are removed from the perpendicular magnetic recording medium 10 by a glide head, a polishing body, or the like. A cleaning process (burnishing, etc.) may be performed.

  As shown in FIG. 1 (b), the adhesion process is such that the magnetic transfer master carrier 20 is adhered to only one surface of the perpendicular magnetic recording medium 10 in the present embodiment. The magnetic transfer master carrier 20 may be brought into close contact with a perpendicular magnetic recording medium (slave disk) having magnetic layers on both sides.

<Magnetic transfer process>
The magnetic transfer step applies a recording magnetic field, which is a magnetic field (Hd) opposite to the initial magnetic field (Hi), to the perpendicular magnetic recording medium 10 and the magnetic transfer master carrier 20 that are in close contact with each other. In this step, information based on the magnetic transfer master carrier 20 is recorded on the perpendicular magnetic recording medium 10.
As shown in FIG. 1 (c), the perpendicular magnetic recording medium 10 and the magnetic transfer master carrier 20 that are in close contact with each other are reversely directed to the initial magnetic field (Hi) by a predetermined magnetic field applying means (not shown). A magnetic field (Hd) is generated.

FIG. 10 is an explanatory view showing a cross-sectional state of the perpendicular magnetic recording medium 10 and the magnetic transfer master carrier 20 in the magnetic transfer process. As shown in FIG. 10, when a recording magnetic field (Hd) is applied with the perpendicular magnetic recording medium 10 and the magnetic transfer master carrier 20 in close contact, the magnetic flux G generated by the magnetic field (Hd) It enters the transfer master carrier 20 and is absorbed by the magnetic layer 40 of the magnetic transfer master carrier 20. As a result, the magnetic field is strengthened in the region of the convex portion 201 of the master carrier 20 for magnetic transfer. On the other hand, the magnetic field in the region of the concave portion 204 of the magnetic transfer master carrier 20 is weaker than the magnetic field in the region of the convex portion 201. In this way, a magnetic field pattern corresponding to information to be recorded on the perpendicular magnetic recording medium 10 is formed.
As a result, in the region corresponding to the convex portion 201, the magnetization direction of the magnetic layer 15 of the perpendicular magnetic recording medium 10 is reversed and information is recorded. In the region corresponding to the concave portion 204, the magnetization of the magnetic layer 15 is recorded. The direction of is not changed.

  FIG. 11 is an explanatory diagram showing the magnetization direction of the magnetic layer of the perpendicular magnetic recording medium after the magnetic transfer process. As shown in FIG. 11, information such as a servo signal is recorded on the magnetic layer 16 of the perpendicular magnetic recording medium 10 as a recording magnetization Pd in the direction opposite to the initial magnetization Pi.

  The recording magnetic field (Hd) is appropriately selected according to the purpose, but in general, a magnetic field having a strength of 40 to 130% of the coercive force (Hc) of the magnetic layer 16 of the perpendicular magnetic recording medium 10 is preferable, and 50 to 120% is more preferable.

  When information is recorded on the perpendicular magnetic recording medium 10 using the magnetic transfer master carrier 20 (when magnetic transfer is performed), for example, the perpendicular magnetic recording medium 10 and the magnetic transfer master carrier 20 that are in close contact with each other are moved to a predetermined rotating means. The magnetic field for recording (Hd) may be applied by the magnetic field applying means while being rotated by (not shown). In another embodiment, a rotating mechanism may be provided in the magnetic field applying unit, and the magnetic field applying unit may be rotated relative to the perpendicular magnetic recording medium 10 and the magnetic transfer master carrier 20.

  FIG. 12 is an explanatory diagram showing an outline of the magnetic transfer apparatus. The magnetic transfer apparatus has a magnetic field applying means 60 composed of an electromagnet in which a coil 63 is wound around a core 62. The magnetic transfer device is configured to generate a magnetic field perpendicularly to the magnetic transfer master carrier 20 and the perpendicular magnetic recording medium 10 in close contact with each other in the gap 64 when an electric current is passed through the coil 63. The direction of the magnetic field to be generated is changed depending on the direction of the current flowing through the coil 63. Therefore, by such a magnetic transfer device, the initial magnetization and magnetic transfer of the perpendicular magnetic recording medium 10 can be performed.

  The perpendicular magnetic recording medium recorded by the magnetic transfer master carrier 20 is used by being incorporated in a magnetic recording / reproducing apparatus such as a hard disk device, for example. The perpendicular magnetic recording medium provides a high recording density magnetic recording / reproducing apparatus with high servo accuracy and good recording / reproducing characteristics.

  Examples of the present invention will be described below. In addition, this invention is not limited to the Example shown below.

[Example 1]
[Master carrier 1 for magnetic transfer]
(Preparation of master)

  An electron beam resist was applied with a thickness of 100 nm on an 8-inch Si wafer (original plate) by spin coating. After coating, the resist on the original plate was irradiated with an electron beam modulated in accordance with servo information or the like using a rotary electron beam exposure apparatus to expose the resist. Thereafter, the resist was developed, unexposed portions were removed, and a pattern of the resist was formed on the original plate.

  Next, using the patterned resist as a mask, a reactive etching process was performed on the original plate, and a portion not masked with the resist was dug down. After the etching treatment, the resist remaining on the original plate was removed by washing with a solvent. Thereafter, the master plate was dried to obtain a master disc for producing a magnetic transfer master carrier.

(Preparation of master carrier 1 for magnetic transfer)
A conductive layer (thickness: 9 nm) made of Ni was formed on the master by a sputtering method. Thereafter, a Ni layer was formed on the master by electroforming using the master on which the conductive layer was formed as a matrix. Thereafter, the Ni layer was peeled off from the master, and the Ni layer was washed to obtain a Ni substrate having convex portions on the surface.

  Next, the substrate is set in a predetermined chamber, and a Ta film (thickness: 3 nm), a Ru film (thickness: 1 nm), and a CoPt film (as a magnetic layer) are formed on the convex portions of the Ni substrate by sputtering. (Thickness: 20 nm) was formed in this order.

An initializing magnetic field was applied to the Ni substrate on which the magnetic layer was formed, thereby initializing the magnetic layer. The conditions for the initial magnetization of the magnetic layer are as follows.
<Initial magnetization condition of magnetic layer>
Initializing magnetic field strength = 10 kOe

The magnetic transfer master carrier 1 was produced as described above.
The coercive force of the magnetic layer of the magnetic transfer master carrier 1 was 0.5 kOe, and the saturation magnetic field was 4.5 kOe.

(Preparation of perpendicular magnetic recording media)
Each layer was formed on a 2.5-inch glass substrate by the following procedure to produce a perpendicular magnetic recording medium.
The manufactured perpendicular magnetic recording medium includes a first nonmagnetic alignment layer, a first soft magnetic layer, a second nonmagnetic alignment layer, a second soft magnetic layer, a third nonmagnetic alignment layer, a magnetic layer, and a protective layer. A layer and a lubricant layer are sequentially formed.
Note that the first nonmagnetic alignment layer, the first soft magnetic layer, the second nonmagnetic alignment layer, the second soft magnetic layer, the third nonmagnetic alignment layer, the magnetic layer, and the protective layer are formed by a sputtering method. The lubricant layer was formed by a dipping method.

<Formation of first nonmagnetic alignment layer>
As the first nonmagnetic alignment layer, a Ti film was formed with a thickness of 4 nm.
Specifically, the glass substrate was placed facing the Ti target, Ar gas was introduced so that the pressure was 0.1 Pa, and DC sputtering film formation was performed.

<Formation of first soft magnetic layer>
As the first soft magnetic layer, a CoZrNb film was formed to a thickness of 20 nm.
Specifically, the glass substrate on which the first nonmagnetic alignment layer has been formed is arranged to face the CoZrNb target, Ar gas is introduced so that the pressure is 0.15 Pa, and DC sputtering film formation is performed. did.

<Formation of Second Nonmagnetic Orientation Layer>
As the second nonmagnetic alignment layer, a Ru film was formed with a thickness of 1 nm.
Specifically, the glass substrate on which the first soft magnetic layer has been formed is placed facing the Ru target, Ar gas is introduced so that the pressure is 0.1 Pa, and DC sputtering film formation is performed. .

<Formation of Second Soft Magnetic Layer>
A CoZrNb film with a thickness of 15 nm was formed as the second soft magnetic layer.
Specifically, the glass substrate on which the second nonmagnetic alignment layer has been formed is placed facing the CoZrNb target, Ar gas is introduced so that the pressure is 0.15 Pa, and DC sputtering film formation is performed. did.

<Formation of third nonmagnetic alignment layer>
As the second nonmagnetic alignment layer, a Ru film was formed with a thickness of 10 nm.
Specifically, the glass substrate on which the second soft magnetic layer has been formed is placed facing the Ru target, Ar gas is introduced so that the pressure is 0.1 Pa, and DC sputtering film formation is performed. .

<Formation of magnetic layer>
A CoCrPtO film having a thickness of 20 nm was formed as the magnetic layer.
Specifically, the glass substrate on which the third nonmagnetic alignment layer has been formed is arranged to face a CoCrPtO target, Ar gas is introduced so that the pressure becomes 0.1 Pa, and DC sputtering film formation is performed. did.

<Formation of protective layer>
As the protective layer, a C film was formed with a thickness of 3 nm.
Specifically, the glass substrate on which the magnetic layer had been formed was placed facing the C target, Ar gas was introduced so that the pressure was 0.5 Pa, and DC sputtering film formation was performed.

<Formation of lubricant layer>
As the lubricant layer, a layer made of PFPE lubricant was formed with a thickness of 1.5 nm.

  The coercive force of the perpendicular magnetic recording medium was 358 kA / m (4.5 kOe).

<Initial magnetization process>
A magnetic field was applied to the perpendicular magnetic recording medium to perform initial magnetization of the perpendicular magnetic recording medium. The intensity of the applied magnetic field is 10 kOe.

(Adhesion process)
The master carrier 1 for magnetic transfer was brought into close contact with the perpendicular magnetic recording medium after initial magnetization at a pressure of 9 kg / cm ² .

(Magnetic transfer process)
A recording magnetic field was applied in a state where the perpendicular magnetic recording medium and the magnetic transfer master carrier 1 were in close contact with each other. The intensity of the recording magnetic field is 4.5 kOe.
Thereafter, the application of the recording magnetic field was stopped, and the magnetic transfer master carrier was separated from the perpendicular magnetic recording medium.

[Evaluation 1]
B / H of the magnetic layer of the master carrier 1 for magnetic transfer was measured. The measuring method is as follows. The results are shown in Table 1.

The same magnetic layer as the magnetic transfer master carrier 1 was formed on a glass substrate (2.5 inches) under the same conditions as in the production of the master carrier. A sample formed on the glass substrate was cut into a size of 6 mm × 8 mm, and the cut sample was subjected to in-plane direction and vibration sample magnetometer (VSM-C7, manufactured by Toei Kogyo Co., Ltd.). A magnetic field was applied in the vertical direction, and the magnetization curve of the sample was measured.
Based on the obtained magnetization curve, the magnetization value (Min) of the in-plane magnetization curve and the magnetization value (Mpe) of the perpendicular magnetization curve at an externally applied magnetic field strength equivalent to the recording magnetic field were calculated.

[Evaluation 2]
The signal S / N of the perpendicular magnetic recording medium magnetically transferred using the magnetic transfer master carrier 1 was evaluated. The measuring method is as follows. The results are shown in Table 1.

A 40 MHz signal was written, and the media characteristics were compared based on the SNR. The reproduced waveform was acquired by a spin stand. The rotation speed of the spin stand was 5000 rpm, and a GMR head was used. When S: 40 MHz ± 1 MHz and N: 0.5 MHz to 80 MHz, the value of 20 * Log ₁₀ (S / (N−S)) was defined as SNR.

[Comparative Example 1]
(Master carrier 11 for magnetic transfer)
A magnetic transfer master carrier 11 was produced in the same manner as in Example 1 except that the magnetic layer was not initially magnetized.
The coercivity of the magnetic layer of the magnetic transfer master carrier 11 was 0.5 kOe, and the saturation magnetic field was 4.5 kOe.
Magnetic transfer was performed in the same manner as in Example 1 using the magnetic transfer master carrier 11.
Further, the magnetic transfer master carrier 11 was evaluated 1 and 2 in the same manner as in Example 1. The results are shown in Table 1.

[Example 2]
(Master carrier 2 for magnetic transfer)
A magnetic transfer master was formed in the same manner as in Example 1 except that a TaSi film (thickness: 3 nm), a Ru film (thickness: 1 nm), and a CoPt film (thickness: 20 nm) were formed in this order as magnetic layers. Carrier 2 was produced.
The coercivity of the magnetic layer of the magnetic transfer master carrier 2 was 0.5 kOe, and the saturation magnetic field was 5.0 kOe.
Magnetic transfer was performed in the same manner as in Example 1 using the magnetic transfer master carrier 2.
Further, the magnetic transfer master carrier 2 was subjected to Evaluation 1 and Evaluation 2 in the same manner as in Example 1. The results are shown in Table 1.

[Comparative Example 2]
(Master carrier 21 for magnetic transfer)
A magnetic transfer master carrier 21 was produced in the same manner as in Example 2 except that the magnetic layer was not initially magnetized.
The coercivity of the magnetic layer of the magnetic transfer master carrier 21 was 0.5 kOe, and the saturation magnetic field was 5.0 kOe.
Magnetic transfer was performed in the same manner as in Example 1 using the magnetic transfer master carrier 21.
Further, the magnetic transfer master carrier 21 was evaluated 1 and 2 in the same manner as in Example 1. The results are shown in Table 1.

Example 3
(Master carrier 3 for magnetic transfer)
A magnetic transfer master was formed in the same manner as in Example 1 except that a Pt film (thickness: 10 nm), a CoCr film (thickness: 2 nm), and a CoPt film (thickness: 15 nm) were formed in this order as the magnetic layer. Carrier 3 was produced.
The coercivity of the magnetic layer of the magnetic transfer master carrier 3 was 1.5 kOe, and the saturation magnetic field was 4.8 kOe.
Magnetic transfer was performed in the same manner as in Example 1 using the magnetic transfer master carrier 3.
Furthermore, the magnetic transfer master carrier 3 was evaluated 1 and 2 in the same manner as in Example 1. The results are shown in Table 1.

[Comparative Example 3]
(Master carrier 31 for magnetic transfer)
A magnetic transfer master carrier 31 was produced in the same manner as in Example 3 except that the magnetic layer was not initially magnetized.
The coercivity of the magnetic layer of the magnetic transfer master carrier 31 was 1.5 kOe, and the saturation magnetic field was 4.8 kOe.
Magnetic transfer was performed in the same manner as in Example 1 using the magnetic transfer master carrier 31.
Further, the magnetic transfer master carrier 31 was evaluated 1 and 2 in the same manner as in Example 1. The results are shown in Table 1.

As shown in Table 1, in Examples 1 to 3, the initial magnetization was performed, so that the Mpe was larger than the Mpe of Comparative Examples 1 to 3 in which the initial magnetization was not performed. Accordingly, it was confirmed that the B / H of the master carriers of Examples 1 to 3 was larger than the B / H of the master carriers of Comparative Examples 1 to 3, respectively.
In Examples 1 to 3, it was confirmed that the S / N value was improved as B / H increased.

FIG. 1 is an explanatory diagram showing an outline of a magnetic transfer method. FIG. 2 is an explanatory view showing an outline of a cross section of the magnetic transfer master carrier. FIG. 3 is an explanatory diagram of the upper surface of the magnetic transfer master carrier. FIG. 4 is an explanatory diagram showing measurement points of the average thickness of the magnetic layer of the master carrier for magnetic transfer. FIG. 5 is an explanatory diagram showing BH curves of the magnetic layer before and after initial magnetization. FIG. 6 is an explanatory view showing a manufacturing process of a master used for manufacturing a magnetic transfer master carrier. FIG. 7 is an explanatory view showing the manufacturing process of the magnetic transfer master carrier. FIG. 8 is an explanatory diagram showing an outline of a cross section of a perpendicular magnetic recording medium. FIG. 9 is an explanatory diagram showing the magnetization direction of the magnetic layer of the perpendicular magnetic recording medium after the initial magnetization. FIG. 10 is an explanatory view showing a cross-sectional state of a perpendicular magnetic recording medium and a magnetic transfer master carrier in magnetic transfer. FIG. 11 is an explanatory diagram showing the magnetization direction of the magnetic layer of the perpendicular magnetic recording medium after magnetic transfer. FIG. 12 is an explanatory diagram showing an outline of the magnetic transfer apparatus.

Explanation of symbols

10 Perpendicular magnetic recording medium (slave disk)
20 Master carrier for magnetic transfer (master disk)
200 Base material 201 Convex portion 202 Tip surface 203 Side surface 204 Concave portion 40 Magnetic layer

Claims (4)

A substrate having on the surface a convex portion disposed corresponding to a pattern of information to be recorded on a perpendicular magnetic recording medium;
A magnetic layer having perpendicular magnetic anisotropy formed at least on a tip surface of the convex part,
When a magnetic field for recording is applied, the magnetic layer absorbs magnetic flux and forms a magnetic field pattern, which is a magnetic transfer master carrier,
A magnetic transfer master carrier, wherein an initializing magnetic field equal to or greater than a coercive force Hc is applied in advance from the same direction as the direction in which the recording magnetic field is applied to the magnetic layer.   The magnetic transfer master carrier according to claim 1, wherein the initialization magnetic field is equal to or higher than a saturation magnetic field Hs. An initial magnetization step in which a perpendicular magnetic recording medium is initially magnetized by applying a magnetic field;
An adhesion step of closely adhering the magnetic transfer master carrier according to claim 1 to an initially magnetized perpendicular magnetic recording medium;
A magnetic field for recording information on the perpendicular magnetic recording medium by applying a recording magnetic field opposite to the magnetic field applied in the initial magnetization step while the perpendicular magnetic recording medium and the magnetic transfer master carrier are in close contact with each other. A magnetic transfer method comprising: a transfer step.   A magnetic recording medium produced using the magnetic transfer method according to claim 3.