JP2010108558A - Magnetic transfer master carrier, method for producing the same, and magnetic transfer method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a magnetic transfer master carrier with high signal quality, which obtains a highly-oriented magnetic layer whose shape hardly degrades even when an underlying layer is thin, and which is superior in signal quality, and a method for producing the same. <P>SOLUTION: The magnetic transfer master carrier includes an oriented base material, a thin underlying layer formed on the oriented base material and the magnetic layer formed on the thin underlying layer.The method of manufacturing the magnetic transfer master carrier includes: a step of applying thermal treatment before forming a conductive layer on a surface of a pattern side of a patterned silicon substrate, a conductive layer forming step of forming an Ni conductive layer on the silicon substrate after thermal treatment, a plating step of applying Ni plating on the silicon substrate having the conductive layer to form a base material, and a pealing step of pealing the base material from the silicon substrate. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

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

  Conventionally, a perpendicular magnetic recording medium is known as a magnetic recording medium capable of recording information at high density. 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 such tracking servo, it is necessary to record servo information such as tracking servo signals, address information signals, and reproduction clock signals on a perpendicular magnetic recording medium at a predetermined interval as a so-called preformat. .

As a method for preformatting servo information on a perpendicular magnetic recording medium, for example, a magnetic field for recording can be obtained in a state where a magnetic transfer master carrier on which a pattern including a magnetic layer corresponding to servo information is formed is in close contact with the magnetic recording medium. There is a method of applying a (transfer magnetic field) and magnetically transferring a pattern of a master carrier for magnetic transfer to a magnetic recording medium (see Patent Documents 1 to 3).
In this method, when a transfer magnetic field is applied with the magnetic transfer master carrier in close contact with the magnetic recording medium, the magnetic flux is absorbed by the magnetic layer on the pattern based on the magnetization state of the master carrier, and the magnetic field is It is strengthened corresponding to the uneven shape. Only a predetermined portion of the magnetic recording medium is magnetized by the magnetic field strengthened in the pattern. So far, magnetic materials having high saturation magnetization have been actively used as master magnetic layer materials.

  As a result of the study by the present inventors, even if a magnetic material having a high saturation magnetization is simply used as the master magnetic layer material, the high saturation magnetization is utilized due to a large demagnetizing field when a transfer magnetic field is applied during transfer. It became clear that not. In order to solve this problem, it has been proposed that a magnetic material having perpendicular magnetic anisotropy is effective as the master magnetic layer material.

  However, in order for the magnetic layer formed on the base material to have a satisfactory perpendicular magnetic anisotropy using the base material of the conventional magnetic transfer master carrier, between the base material and the magnetic layer, , It is necessary to provide a thick underlayer, and when trying to obtain a sufficient orientation by thickening the underlayer, the shape of the magnetic layer formed on the substrate deteriorates, the distribution of the transfer magnetic field deteriorates, There is a problem that the signal quality of the recording signal deteriorates, and it is currently desired to solve the problem.

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 conventional problems and achieve the following objects. That is, the present invention provides a magnetic transfer master carrier that is highly oriented and has no shape deterioration even when the underlayer is thin, and has excellent signal quality, a method for producing the magnetic transfer master carrier, and the magnetic It is an object of the present invention to provide a magnetic transfer method using a transfer master carrier.

  As a result of intensive studies by the present inventors in order to solve the above-mentioned problems, in the method for producing a magnetic transfer master carrier, Ni (111) is obtained by performing a heat treatment before or after forming the Ni conductive layer. It has been found that the c-axis orientation of the hcp structure magnetic film can be improved only by forming a thin underlayer on the Ni substrate.

The present invention is based on the above findings by the present inventors, and means for solving the above problems are as follows. That is,
<1> A method for producing a master carrier for magnetic transfer, comprising an orientation substrate, a base thin layer formed on the orientation base, and a magnetic layer formed on the base thin layer,
A heat treatment step before forming a conductive layer for heat treating the patterned surface of the patterned silicon substrate; and
A conductive layer forming step of forming a Ni conductive layer on the silicon substrate after the heat treatment;
On the silicon substrate having the conductive layer, Ni plating is performed to form a base material;
A peeling step of peeling the base material from the silicon substrate;
A method for producing a master carrier for magnetic transfer.
<2> The method for producing a master carrier for magnetic transfer according to <1>, wherein the heat treatment is performed at 300 ° C. to 450 ° C. for 20 minutes to 40 minutes.
<3> A method for producing a master carrier for magnetic transfer, comprising an orientation substrate, a base thin layer formed on the orientation base, and a magnetic layer formed on the base thin layer,
A conductive layer forming step of forming a Ni conductive layer on the patterned silicon substrate;
A heat treatment step after the formation of the conductive layer for heat-treating the surface of the Ni conductive layer;
On the silicon substrate having the conductive layer after the heat treatment, Ni plating is performed to form a base material;
A peeling step of peeling the base material from the silicon substrate;
A method for producing a master carrier for magnetic transfer.
<4> The method for producing a magnetic transfer master carrier according to <3>, wherein the heat treatment is performed at 300 ° C. to 450 ° C. for 10 minutes to 30 minutes.
<5> A magnetic transfer master carrier produced by the method for producing a magnetic transfer master carrier according to any one of <1> to <4>.
<6> The magnetic transfer master carrier according to <5>, wherein the thickness of the base thin layer is 1 nm to 30 nm.
<7> an initial magnetization step of initially magnetizing the perpendicular magnetic recording medium in the perpendicular direction;
An adhesion step of bringing the magnetic transfer master carrier according to any one of <5> to <6> into close contact with the perpendicular magnetic recording medium after the initial magnetization step;
A magnetic transfer step of transferring magnetic information to the perpendicular magnetic recording medium by applying a perpendicular magnetic field opposite to the initial magnetization in a state where the perpendicular magnetic recording medium and the magnetic transfer master carrier are in close contact with each other; It is a magnetic transfer method characterized by including.

  According to the present invention, the above-described conventional problems can be solved, the above-mentioned object can be achieved, and a magnetic layer having a high orientation and no shape deterioration can be obtained even if the underlayer is thinned. Master transfer carrier, a method for producing the magnetic transfer master carrier, and a magnetic transfer method using the magnetic transfer master carrier.

(Method for producing magnetic transfer master carrier and magnetic transfer master carrier)
The method for producing a magnetic transfer master carrier of the present invention comprises an alignment substrate, a base thin layer formed on the alignment substrate, and a magnetic layer formed on the base thin layer. A method for producing a carrier.
The first mode includes a heat treatment step before forming the conductive layer, a conductive layer forming step, a plating step, and a peeling step, and further includes other steps as necessary.
The second mode includes a conductive layer forming step, a heat treatment step after forming the conductive layer, a plating step, and a peeling step, and further includes other steps as necessary.
The magnetic transfer master carrier of the present invention is produced by the method for producing a magnetic transfer master carrier of the present invention.
Hereinafter, details of the magnetic transfer master carrier of the present invention will be clarified through the description of the method of manufacturing the magnetic transfer master carrier of the present invention.

<Method for Manufacturing Master Carrier for Magnetic Transfer of First Embodiment>
-Heat treatment process before conductive layer formation-
The heat treatment step before forming the conductive layer is a step of heat-treating the patterned surface of the patterned silicon substrate. Thereby, the concave surface of the Si substrate becomes SiO ₂ amorphous instead of Si. As a result, (111) orientation is facilitated when forming the Ni conductive layer.

The heat treatment step before forming the conductive layer is preferably performed at a temperature of 300 ° C. to 450 ° C. for a time of 20 minutes to 40 minutes, and at a temperature of 400 ° C. to 450 ° C. for a time of 30 minutes to 40 minutes. More preferred.
When the temperature is low or the heat treatment time is short, the effect of improving the orientation by heat treatment may be reduced, and when the temperature is too high or the heat treatment time is too long, the surface is exposed to a high temperature. Another harmful effect may occur.
The heat treatment is not particularly limited and can be appropriately selected depending on the purpose. For example, (1) a method using a clean oven, (2) a method using an apparatus using ultrasonic waves or microwaves, etc. Can do.

-Conductive layer formation process-
The conductive layer forming step is a step of forming a Ni conductive layer on the silicon substrate after the heat treatment. By forming the conductive layer, the effect that the electrodeposition of metal during electroforming can be performed uniformly is obtained.
The formation of the Ni conductive layer is not particularly limited and may be appropriately selected depending on the purpose. Examples thereof include various metal film formation methods such as PVD (Physical Vapor Deposition) and CVD (Chemical Vapor Deposition). . Among these, the sputtering method is particularly preferable.
There is no restriction | limiting in particular in the thickness of the said Ni conductive layer, According to the objective, it can select suitably, It is preferable that it is 1-30 nm.
The Ni conductive layer may contain a material other than Ni, or may have a multilayer structure of the Ni layer and other material layers.

-Plating process-
The plating step is a step of forming a base material by performing Ni plating on a silicon substrate having the conductive layer.
There is no restriction | limiting in particular as the implementation method of the said plating process, According to the objective, it can select suitably, For example, methods, such as electroplating, are suitable.
The electroplating is performed by immersing the master in an electrolytic solution of an electroforming apparatus, using the master as an anode, and energizing the cathode. The concentration, pH, current application method, and the like of the electrolytic solution at this time are carried out under optimum conditions with no distortion in the laminated metal plate (that is, the magnetic transfer master carrier).

-Peeling process-
The peeling step is a step of peeling the base material from the silicon substrate.
There is no restriction | limiting in particular as an implementation method of the said peeling process, According to the objective, it can select suitably, For example, methods, such as physical peeling with a dedicated jig, can be utilized.

-Other processes-
There is no restriction | limiting in particular as said other process, According to the objective, it can select suitably, For example, a base thin film formation process, a magnetic layer formation process, a protective film formation process, etc. are mentioned.

<Method for Producing Magnetic Transfer Master Carrier in Second Embodiment>
-Conductive layer formation process-
The conductive layer forming step is a step of forming a Ni conductive layer on the patterned silicon substrate, and is the same as in the first embodiment.

-Heat treatment process after formation of conductive layer-
The heat treatment step after forming the conductive layer is a step of heat treating the surface of the Ni conductive layer. Thereby, the (111) orientation of the Ni conductive layer can be enhanced.

The heat treatment step after forming the conductive layer preferably has a temperature of 300 ° C. to 450 ° C. and a time of 10 minutes to 30 minutes, and a temperature of 300 ° C. to 400 ° C. and a time of 10 minutes to 20 minutes. More preferred.
When the temperature is low or the heat treatment time is short, the effect of improving the orientation by heat treatment may be reduced, and when the temperature is too high or the heat treatment time is too long, the surface is exposed to a high temperature. Another harmful effect may occur.
The heat treatment is not particularly limited and can be appropriately selected depending on the purpose. For example, (1) a method using a clean oven, (2) a method using an apparatus using ultrasonic waves or microwaves, etc. Can do.

-Plating process-
The plating step is a step of performing Ni plating on a silicon substrate having a conductive layer after the heat treatment to form a base material, and is the same as in the first embodiment.

-Peeling process-
The peeling step is the same as in the first embodiment.

-Other processes-
There is no restriction | limiting in particular as said other process, According to the objective, it can select suitably, For example, a base thin film formation process, a magnetic layer formation process, a protective film formation process, etc. are mentioned.

Here, FIG. 1 to FIG. 3 are explanatory views showing a manufacturing process of a magnetic transfer master carrier (hereinafter sometimes abbreviated as a master disk or a master carrier). Hereinafter, an example of a method for manufacturing a master disk according to an embodiment will be described with reference to FIGS.
As shown in FIG. 1A, an original plate 30 which is a silicon wafer having a smooth surface is prepared, and an electron beam resist solution is applied onto the original plate 30 by a spin coat method or the like to form a resist layer 32. (See FIG. 1B), and baking processing (pre-baking) is performed.

  Next, an original plate 30 is set on a stage of an electron beam exposure apparatus (not shown) equipped with a high-precision rotary stage or an XY stage, and an electron beam modulated in accordance with a servo signal is rotated while the original plate 30 is rotated. A predetermined pattern 33, for example, a pattern corresponding to a servo signal extending linearly from the center of rotation to each track in a radial direction on each track is drawn and exposed on a portion corresponding to each frame on the circumference (subject to irradiation). Electron beam drawing) (see FIG. 1C).

  Next, as shown in FIG. 1D, the resist layer 32 is developed to remove the exposed (drawn) portion, and a coating layer having a desired thickness is formed by the remaining resist layer 32. This coating layer becomes a mask for the next process (etching process). The resist applied on the substrate 30 can be either a positive type or a negative type, but the exposure (drawing) pattern is reversed between the positive type and the negative type. After this development process, a baking process (post-bake) is performed to increase the adhesion between the resist layer 32 and the original plate 30.

  Next, as shown in FIG. 1E, the original plate 30 is removed (etched) from the surface by a predetermined depth from the opening of the resist layer 32. In this etching, anisotropic etching is preferable in order to minimize undercut (side etching). As such anisotropic etching, reactive ion etching (RIE) can be preferably employed.

Next, as shown in FIG. 2F, the resist layer 32 is removed. As a method for removing the resist layer 32, ashing can be employed as a dry method, and a removal method using a stripping solution can be employed as a wet method. Through the above ashing process, a master (silicon substrate) 36 on which a reverse type of a desired concavo-convex pattern is formed is produced.
Here, in the method for manufacturing a magnetic transfer master carrier according to the first embodiment of the present invention, the patterned silicon substrate is placed in a clean oven, and heat is applied to the surface on the substrate pattern side. Heat treatment is performed at ˜450 ° C. for 20 minutes to 40 minutes.

Next, as shown in FIG. 2G, a conductive layer 38 is formed on the surface of the master 36 to a uniform thickness. As a method for forming the conductive layer 38, various metal film forming methods including PVD (Physical Vapor Deposition) and CVD (Chemical Vapor Deposition) can be applied.
Thus, if one layer of the conductive layer (reference numeral 38) is formed, the effect that the electrodeposition of the metal in the next process (electroforming process) can be performed uniformly is obtained. The conductive layer 38 is preferably a film containing Ni as a main component. Such a film containing Ni as a main component is suitable for a conductive layer because it is easy to form and is hard. Although there is no restriction | limiting in particular as the thickness of this conductive layer 38, about several dozen nm is generally employable.
In the method of manufacturing the master carrier for magnetic transfer according to the second embodiment of the present invention, unlike the first embodiment, after forming the Ni conductive layer, the substrate with the Ni conductive layer is placed in a clean oven, Heat is applied to the Ni conductive layer surface on the pattern side, specifically, heat treatment is performed at 300 to 450 ° C. for 10 to 30 minutes.

  Next, as shown in FIG. 2H, a metal plate 40 made of a metal (here, Ni) having a desired thickness is laminated on the surface of the master 36 by electroforming (plating step). This plating process is performed by immersing the master 36 in the electrolyte of the electroforming apparatus, and using the master 36 as an anode and energizing between the cathode and the electrolyte. At this time, the concentration of the electrolyte, pH, and application of current The method is required to be performed under optimum conditions with no distortion in the laminated metal plates 40.

  Then, the master 36 on which the metal plate 40 is laminated as described above is taken out from the electrolytic solution of the electroforming apparatus and immersed in pure water in a peeling tank (not shown).

  Next, in the peeling tank, the metal plate 40 is peeled from the master 36 (peeling step), and a rough master substrate 42A (base material) having a concavo-convex pattern reversed from the master 36 as shown in FIG. obtain.

  Subsequently, the surface of the rough master substrate 42A is etched to roughly remove the conductive layer 38 to obtain a master substrate 42 (alignment base material) as shown in FIG. 3 (j) (etching step).

  Next, as shown in FIG. 3K, a base thin layer 47 is formed on the uneven surface of the master substrate 42. The material of the underlying thin layer 47 is made of, for example, a metal, an alloy, or a compound containing at least one of Pt, Ru, Pd, Co, Cr, Ni, W, Ta, Al, P, Si, and Ti. . The thickness of the underlying thin layer 47 is preferably in the range of 1 nm to 30 nm, and more preferably in the range of 2 nm to 20 nm. The underlying thin layer 47 is formed, for example, by sputtering using the above-described material target.

  Next, as shown in FIG. 3L, a magnetic layer 48 is formed on the underlying thin layer 47. The material of the magnetic layer 48 is made of, for example, CoPt. The thickness of the magnetic layer 48 is preferably in the range of 10 nm to 320 nm, more preferably in the range of 20 nm to 300 nm, and still more preferably 30 nm to 100 nm. The magnetic layer 48 is formed by sputtering using a target of the material described later.

  Thereafter, the inner diameter and the outer diameter of the master substrate 42 are punched into a predetermined size. Through the above process, as shown in FIG. 3L, the master disk 20 having the concavo-convex pattern provided with the magnetic layer 48 is manufactured.

  FIG. 4 is a top view of the master disk 20. As shown in FIG. 4, a servo pattern 52 composed of a concavo-convex pattern is formed on the surface of the master disk 20. Although not shown in the figure, a protective film (protective layer) such as diamond-like carbon is formed on the magnetic layer 48 (see FIG. 3 (l)) on the surface of the master disk 20, and a lubricant layer is formed on the protective film. May be provided.

  The purpose of forming the protective layer is to prevent the magnetic layer 48 from being easily damaged when the master disk 20 and a slave disk to be described later are brought into close contact with each other and cannot be used as the master disk 20. In addition, the lubricant layer has an effect of preventing the occurrence of scratches due to friction generated when contacting the slave disk and improving durability.

  Specifically, a structure in which a carbon film having a thickness of 2 nm to 30 nm is formed as a protective layer and a lubricant layer is further formed thereon is preferable. Further, in order to reinforce the adhesion between the magnetic layer 48 and the protective layer, an adhesion reinforcing layer such as Si may be formed on the magnetic layer 48 and then the protective layer may be formed.

(Master carrier for magnetic transfer)
The magnetic transfer master carrier of the present invention is produced by the above-described method for producing a magnetic transfer master carrier, and includes at least an orientation substrate, a base thin layer formed on the orientation base, and a base thin layer. The magnetic layer is formed, and other layers are further provided as necessary.

FIG. 5A is a partial cross-sectional view of a master disk (master carrier) 20 as an example of the magnetic transfer master carrier of the present invention. The master disk 20 includes an orientation base 202 and a magnetic layer 204 formed on the surface of the orientation base 202. The alignment substrate 202 has a convex portion 206 and a concave portion 207 on its surface. The convex portion 206 has the magnetic layer 204 on the surface thereof. In the present embodiment, the magnetic layer 208 is also formed on the surface of the recess 207 for reasons such as easy manufacture. In other embodiments, the magnetic layer 208 may not be in the recess 207.
The magnetic layer 204 formed on the surface (top surface) of the convex portion 206 of the alignment substrate 202 becomes a bit portion corresponding to the transfer signal. This bit portion is a portion that reverses the initial magnetization, and corresponds to a transfer portion. The concave portion 207 corresponds to a non-transfer portion where magnetization is not reversed.

  FIG. 5B is a partial cross-sectional view of a master disk 20A according to another embodiment. The master disk 20A includes an orientation base 212 and a magnetic layer 214 serving as a bit portion corresponding to a transfer signal on the surface of the orientation base 212. In the master disk 20A, the magnetic layer 214 corresponds to a transfer portion, and a portion (gap) between adjacent magnetic layers 214 corresponds to a non-transfer portion.

<Oriented substrate>
The alignment substrate is manufactured using a known material such as a synthetic resin such as glass or polycarbonate; a metal such as nickel or aluminum; silicon or carbon.

<Magnetic layer>
The magnetic layer preferably has perpendicular magnetic anisotropy and has a magnetic anisotropy energy (Ku) of 3 × 10 ⁶ erg / cm ³ or more. The magnetic anisotropy energy (Ku) can be measured using a known magnetic anisotropy torque meter.

When the magnetic layer has a magnetic anisotropy energy of at least 3 × 10 ⁶ erg / cm ³ , when a transfer magnetic field (Hd) is applied, a demagnetizing field in the magnetic layer when a magnetic field is applied in a vertical direction is applied. Reduction in the amount of magnetization due to the influence is suppressed. On the other hand, when the magnetic anisotropy energy is less than 3 × 10 ⁶ erg / cm ³ , when a transfer magnetic field (Hd) is applied, the influence of the demagnetizing field generated in the magnetic layer appears remarkably. The amount of magnetization of the magnetic layer is reduced, and the magnetic transfer characteristics cannot be ensured.

  The saturation magnetization (Ms) of the magnetic layer is preferably 500 emu / cc or more. When the saturation magnetization is less than 500 emu / cc, it has perpendicular magnetic anisotropy and the magnetic layer magnetization is in a saturated state. May not be secured.

The nucleation magnetic field (Hn) of the magnetic layer is preferably a positive value (Hn> 0). When the nucleation magnetic field (Hn) is Hn ≦ 0, a large magnetic field is generated from the magnetic layer even after the transfer magnetic field is removed after the magnetic transfer is completed, and overrecording occurs, and a desired signal cannot be recorded. is there.
The nucleation magnetic field (Hn) of the magnetic layer is preferably not more than the applied magnetic field (transfer magnetic field, Hd). The saturation magnetization (Ms) of the magnetic layer can be effectively utilized when the applied magnetic field is not more than the applied magnetic field.

  The saturation magnetization (emu / cc) and the nucleation magnetic field (Hn) of the magnetic layer are obtained using a known vibrating sample magnetometer. The saturation magnetization (emu / cc) is obtained from the magnetization curve obtained using the vibrating sample magnetometer, and the saturation magnetic moment (emu) is obtained, and the saturation magnetic moment is divided by the volume (cc) of the magnetic layer. Is required. The nucleation magnetic field (Hn) is obtained from the magnetization curve.

  The remanent magnetization (Mr) of the magnetic layer is preferably a small value. If the remanent magnetization exceeds a certain value, a magnetic field is generated from the master disk even after the application of the transfer magnetic field is cancelled.Therefore, unnecessary transfer occurs when separating the master disk from the slave disk. Signal noise. The remanent magnetization (Mr) of the magnetic layer is preferably 80% or less of the saturation magnetization value, specifically, 400 emu / cc or less.

  If the value of the coercive force (Hc) of the magnetic layer is too large, it is difficult to transfer because the magnetic layer is not magnetized by the applied magnetic field. Application of a large transfer magnetic field strengthens the magnetic field in the recess. Therefore, the coercive force (Hc) of the magnetic layer is preferably less than or equal to the coercivity of the target perpendicular magnetic recording medium, specifically, preferably 6,000 Oe or less, and more preferably 4,000 Oe or less.

  As a material used for the magnetic layer of such a master disk (master carrier), at least one ferromagnetic metal of Fe, Co, and Ni, and Cr, Pt, Ru, Pd, Si, Ti, B, It is an alloy or compound composed of at least one nonmagnetic substance of Ta and O. As the material of the magnetic layer, an alloy (CoPt) composed of Co and Pt is particularly preferable.

Using the master disk on which the hard protective layer and the lubricant layer are formed, magnetic transfer is performed a plurality of times.
By the way, in addition to the presence of minute pinholes in the hard protective layer, the coverage of the lubricant layer is also low, so that moisture penetrates from the pinholes in multiple magnetic transfer processes, and the surface of the conventional master disk In some cases, a magnetic layer oxide was formed. As a result of the formation of the oxide, the volume of the magnetic layer expands, the expanded portion becomes convex, and physical defects may occur on the surface of the slave disk.
In particular, when a conventional master disk having a magnetic layer made of FeCo is brought into contact, there is a problem that corrosion and oxidation of metal elements, particularly Fe, of the magnetic layer are selectively generated.
On the other hand, a master disk having a magnetic layer made of CoPt selected from Co and Pt, which has a lower ionization tendency than Fe, can greatly improve the above problem.

  The magnetic layer of the master disk (master carrier) can be formed by sputtering, for example. For example, when CoPt is used as the magnetic layer, the composition of the magnetic layer can be controlled mainly by the Pt concentration. When the sputtering pressure during the formation of the magnetic layer is set low, the magnetic anisotropy energy (Ku) can be increased. However, when the sputtering pressure is set to less than 0.1 Pa, discharge is usually difficult. The sputtering pressure is preferably from 0.1 Pa to 50 Pa, more preferably from 0.1 Pa to 10 Pa. The Pt concentration is preferably 5 atom% to 30 atom%, more preferably 10 atom% to 25 atom%.

<Thin base layer>
The underlying thin layer is formed under the magnetic layer (magnetic layer) in order to adjust the perpendicular orientation, magnetic anisotropy energy (Ku), and nucleation magnetic field (Hn) of the magnetic layer of the master disk (master carrier). And the alignment substrate).
Examples of the material for the base thin layer include Pt, Ru, Pd, Co, Cr, Ni, W, Ta, Al, P, Si, and a metal, an alloy, or a compound containing at least one of Ti. Is done. As the material for the underlying thin layer, a white metal such as Pt or Ru or an alloy is preferable. The underlying thin layer may be a single layer or a multilayer.

The thickness of the base thin layer is preferably 1 nm to 30 nm, and more preferably 2 nm to 20 nm. If the thickness of the underlying thin layer exceeds 30 nm, the shape of the magnetic layer formed on the pattern of the master disk deteriorates, the distribution of the transfer magnetic field deteriorates, and the signal quality of the recording signal deteriorates. On the other hand, if the thickness of the underlying thin layer is less than 1 nm, the magnetic layer may not be vertically aligned, or the magnetic anisotropy energy and the nucleation magnetic field may not be controlled.
In addition, it is preferable that the thickness of the said foundation | substrate thin layer is 20 nm or less. When the thickness of the underlying thin layer is 20 nm or less, the deterioration of the pattern shape after forming the magnetic layer can be suppressed, and the magnetic transfer characteristics can be greatly improved.

Conventionally, in order to vertically align the magnetic layer, the underlayer has to have a thickness exceeding 30 nm.
In contrast, in the present invention, since the surface orientation of the substrate is high, the magnetic layer can be vertically oriented even if the underlayer is thin. As a result, the total thickness of the underlayer and the magnetic layer formed on the substrate can be suppressed, and as a result, it is possible to obtain excellent transfer signal quality without being affected by the shape deterioration of the magnetic layer.

<Other layers>
There is no restriction | limiting in particular as said other layer, According to the objective, it can select suitably, For example, protective layer formation etc. are mentioned.

<< Protective layer >>
The protective layer is formed on the master disk surface in order to improve mechanical, frictional properties, and weather resistance. As the material of the protective layer, a hard carbon film is preferable, and inorganic carbon, diamond-like carbon, or the like formed by a sputtering method can be used. A layer made of a lubricant (lubricant layer) may be further formed on the hard protective layer.
As this type of lubricant, a fluorine-based resin such as perfluoropolyether (PFPE) is generally used.

(Magnetic transfer method)
The magnetic transfer method of the present invention includes at least an initial magnetization step, an adhesion step, and a magnetic transfer step, and further includes other steps as necessary.

  The outline of the magnetic transfer technique of perpendicular magnetic recording will be described with reference to FIG. FIG. 6 is an explanatory diagram showing the steps of a magnetic transfer method for perpendicular magnetic recording. In FIG. 6, 10 denotes a slave disk (corresponding to a perpendicular magnetic recording medium) as a magnetic disk for transfer, and 20 denotes a master disk as a magnetic transfer master carrier.

As shown in FIG. 6A, a DC magnetic field (Hi) is applied from a direction perpendicular to the disk plane of the slave disk 10 to initially magnetize the slave disk 10 (initial magnetization step).
After the initial magnetization, as shown in FIG. 6B, the slave disk 10 after the initial magnetization and the master disk 20 are brought into close contact (contact process).
Further, after the disks 10 and 20 are brought into close contact with each other, as shown in FIG. 6C, a magnetic field (Hi) applied in the direction opposite to the magnetic field (Hi) applied at the time of initial magnetization is applied. Magnetic transfer to the slave disk 10 (magnetic transfer step).

[Description of slave disk (perpendicular magnetic recording medium)]
As shown in FIG. 7, the slave disk 10 is a disk in which a slave magnetic layer is formed on one surface or both surfaces of a disk-shaped substrate, and specifically includes a high-density hard disk. Taking this slave disk 10 as an example, a perpendicular magnetic recording medium will be described with reference to FIG.

  FIG. 7 is an explanatory diagram showing a cross section of the slave disk 10. As shown in FIG. 7, the slave disk 10 includes a soft magnetic layer (soft magnetic underlayer; SUL) 13, a nonmagnetic layer (intermediate layer) 14, a slave magnetic layer (perpendicular magnetic) on a nonmagnetic substrate 12 such as glass. Recording layer) 16 is sequentially laminated, and the slave magnetic layer 16 is further covered with a protective layer 18 and a lubricating layer 19. Here, an example in which the slave magnetic layer 16 is formed on one surface of the substrate 12 is shown, but an embodiment in which the slave magnetic layer is formed on both front and back surfaces of the substrate 12 is also possible.

  The substrate 12 has a disk shape and is made of a nonmagnetic material such as glass or Al (aluminum). After the soft magnetic layer 13 is formed on the substrate 12, the nonmagnetic layer 14 and the slave magnetic layer are formed. 16 is formed.

  The soft magnetic layer 13 is useful for stabilizing the perpendicular magnetization state of the slave magnetic layer 16 and improving the sensitivity during recording and reproduction. The material used for the soft magnetic layer 13 is preferably a soft magnetic material such as CoZrNb, FeTaC, FeZrN, FeSi alloy, FeAl alloy, FeNi alloy such as permalloy, and FeCo alloy such as permendur. The soft magnetic layer 13 has a magnetic anisotropy having an easy axis in the radial direction from the center of the disk to the outside.

  The thickness of the soft magnetic layer 13 is preferably 20 nm to 2,000 nm, and more preferably 40 nm to 400 nm.

  The nonmagnetic layer 14 is provided for reasons such as increasing the perpendicular magnetic anisotropy of the slave magnetic layer 16 to be formed later. As the material used for the nonmagnetic layer 14, for example, Ti (titanium), Cr (chromium), CrTi, CoCr, CrTa, CrMo, NiAl, Ru (ruthenium), Pd (palladium), Ta, Pt and the like are preferable. The nonmagnetic layer 14 is formed by depositing the above material by a sputtering method. The thickness of the nonmagnetic layer 14 is preferably 10 nm to 150 nm, and more preferably 20 nm to 80 nm.

The slave magnetic layer 16 is formed of a perpendicular magnetization film (with the easy magnetization axis in the slave magnetic layer oriented mainly perpendicular to the substrate), and information is recorded on the slave magnetic layer 16. Examples of the material used for the slave magnetic layer 16 include Co (cobalt), Co alloy (CoPt, CoPtCr, CoCr, CoPtCrTa, CoPtCrNbTa, CoCrB, CoNi, etc.), Co alloy-SiO ₂ , Co alloy-TiO ₂ , and Fe alloy. (FePt, FeCoNi, etc.) are preferred. These materials have a large magnetic flux density and have perpendicular magnetic anisotropy by adjusting film forming conditions and composition. The slave magnetic layer 16 is formed by depositing the above material by a sputtering method. The thickness of the slave magnetic layer 16 is preferably 10 nm to 500 nm, and more preferably 20 nm to 200 nm.

In the present embodiment, a disk-shaped glass substrate having an outer diameter of 65 mm is used as the substrate 12 of the slave disk 10, and the glass substrate is installed in the chamber of the sputtering apparatus to obtain 1.33 × 10 ⁻⁵ Pa (1.0 × 10 6). ^-7 Torr), Ar (argon) gas is introduced into the chamber, the CoZrNb target in the chamber is used, and the temperature of the substrate in the chamber is set to room temperature, and the SUL first layer having a thickness of 80 nm is sputtered. Form a film. Next, a 0.8 nm Ru layer is formed by sputtering using a Ru target in the chamber. Further, a SUL second layer having a thickness of 80 nm is formed by sputtering using a CoZrNb target. Incidentally, when forming the SUL first layer and the second layer, a magnetic anisotropy having an axis of easy magnetization in the radial direction is imparted by applying a magnetic field of 50 (Oe) or more in the radial direction.

  Next, sputtering film formation is performed by using a Ru target and discharging the substrate at a room temperature. Thereby, the nonmagnetic layer 14 made of Ru is formed to a thickness of 20 nm.

Thereafter, Ar gas is introduced in the same manner as described above, and sputtering film formation is performed by using a CoCrPt—SiO ₂ target in the same chamber and discharging the substrate at the same room temperature. Thereby, the slave magnetic layer 16 having a granular structure made of CoCrPt—SiO ₂ is formed to a thickness of 20 nm.

  Through the above process, a magnetic disk for transfer (slave disk) 10 in which a soft magnetic layer, a nonmagnetic layer, and a slave magnetic layer were formed on a glass substrate was produced.

<Initial magnetization process>
As shown in FIG. 6A, the initial magnetization (DC magnetization) of the slave disk 10 is initialized by a device (magnetic field applying means not shown) that can apply a DC magnetic field perpendicular to the surface of the slave disk 10. This is performed by generating the activating magnetic field Hi. Specifically, the initialization magnetic field Hi is generated by generating a magnetic field having a strength equal to or greater than the coercive force Hc of the slave disk 10. By this initial magnetization process, as shown in FIG. 8, the slave magnetic layer 16 of the slave disk 10 is initially magnetized Pi in one direction perpendicular to the disk surface. This initial magnetization step may be performed by rotating the slave disk 10 relative to the magnetic field applying means.

<Adhesion process>
Next, as shown in FIG. 6B, the master disk 20 and the slave disk 10 after the initial magnetization process are overlaid and brought into close contact (contact process). As shown in FIG. 6B, in the contact process, the surface of the master disk 20 on which the projection pattern (uneven pattern) is formed and the surface of the slave disk 10 on which the slave magnetic layer 16 is formed are predetermined. Adhere with the pressing force of.

  Before being brought into close contact with the master disk 20, the slave disk 10 is subjected to a cleaning process (burnishing or the like) for removing minute protrusions or adhering dust on the surface by a glide head, a polishing body, or the like as necessary.

  As shown in FIG. 6 (b), the contact process includes a case where the master disk 20 is brought into close contact with only one side of the slave disk 10 and a case where the transfer magnetic disk having the slave magnetic layer formed on both sides is mastered from both sides. In some cases, the disk is in close contact. The latter case has an advantage that both sides can be transferred simultaneously.

<Magnetic transfer process>
Next, the magnetic transfer process will be described with reference to FIG. In the case where the slave disk 10 and the master disk 20 are brought into close contact with each other in the contact step, a recording magnetic field Hd is generated in a direction opposite to the direction of the initialization magnetic field Hi by a magnetic field applying means (not shown). Magnetic transfer is performed by the magnetic flux generated by generating the recording magnetic field Hd entering the slave disk 10 and the master disk 20.

  In this embodiment, the magnitude of the recording magnetic field Hd is substantially the same value as Hc of the magnetic material constituting the slave magnetic layer 16 of the slave disk 10.

  In the magnetic transfer, a recording magnetic field Hd is applied by a magnetic field applying means while rotating a close contact of the slave disk 10 and the master disk 20 by a rotating means (not shown), and the protruding shape recorded on the master disk 20 is applied. Information consisting of the pattern is magnetically transferred to the slave magnetic layer 16 of the slave disk 10. In addition to this configuration, a mechanism for rotating the magnetic field applying unit may be provided to rotate the slave disk 10 and the master disk 20 relatively.

  FIG. 9 shows a cross-sectional state of the slave disk 10 and the master disk 20 in the magnetic transfer process. As shown in FIG. 9, when the recording magnetic field Hd is applied in a state where the master disk 20 having the uneven pattern is in close contact with the slave disk 10, the magnetic flux G causes the convex area of the master disk 20 and the slave disk 10 to contact each other. The magnetic field for recording Hd aligns the magnetization direction of the magnetic layer 48 of the master disk 20 with the direction of the magnetic field for recording Hd, and magnetic information is transferred to the slave magnetic layer 16 of the slave disk 10. On the other hand, in the concave area of the master disk 20, the magnetic flux G generated by the application of the recording magnetic field Hd is weaker than that of the convex area, the magnetization direction of the slave magnetic layer 16 of the slave disk 10 does not change, and the initial magnetization state Is kept.

  FIG. 10 shows in detail a magnetic transfer apparatus used for magnetic transfer. This magnetic transfer device has a magnetic field applying means 60 composed of an electromagnet having a coil 63 wound around a core 62, and a master disk 20 and a slave that are brought into close contact with each other in a gap 64 by passing an electric current through the coil 63. The magnetic field is generated perpendicular to the slave magnetic layer 16 of the disk 10. The direction of the generated magnetic field can be changed depending on the direction of the current flowing through the coil 63. Therefore, it is possible to perform the initial magnetization of the slave disk 10 and the magnetic transfer by this magnetic transfer device.

  When magnetic transfer is performed after the initial magnetization by the magnetic transfer device, a current having a direction opposite to the direction of the current flowing in the coil 63 when the initial magnetization is performed is supplied to the coil 63 of the magnetic field applying unit 60. As a result, the recording magnetic field can be generated in a direction opposite to the magnetization direction during the initial magnetization. Magnetic transfer is performed by applying a magnetic field for recording Hd by the magnetic field applying means 60 while rotating the disk in which the slave disk 10 and the master disk 20 are in close contact with each other, so that information consisting of a protruding pattern recorded on the master disk 20 is obtained. A rotating means (not shown) is provided for magnetic transfer to the slave magnetic layer 16 of the slave disk 10. In addition to this configuration, a mechanism that rotates the magnetic field applying unit 60 and rotates the slave disk 10 and the master disk 20 relatively may be used.

  In the present embodiment, the recording magnetic field Hd is preferably 40% to 130%, more preferably 50% to 120% of the coercive force Hc of the slave magnetic layer 16 of the slave disk 10 used in the present embodiment. Magnetic transfer is performed by applying a magnetic field.

  As a result, information on the magnetic pattern such as a servo signal is recorded on the slave magnetic layer 16 of the slave disk 10 as the recording magnetization Pd having the magnetization opposite to the initial magnetization Pi (see FIG. 11).

  In carrying out the present invention, the protruding pattern formed on the master disk 20 may be a negative pattern opposite to the positive pattern described in FIG. In this case, the same magnetization pattern can be magnetically transferred to the slave magnetic layer 16 of the slave disk 10 by reversing the direction of the initialization magnetic field Hi and the direction of the recording magnetic field Hd. In the present embodiment, the magnetic field applying unit has been described as being an electromagnet. However, a permanent magnet that similarly generates a magnetic field may be used.

  The perpendicular magnetic recording medium manufactured by the method according to the embodiment of the present invention described above is used by being incorporated in a magnetic recording / reproducing apparatus such as a hard disk device, for example. Thereby, a high recording density magnetic recording / reproducing apparatus having high servo accuracy and good recording / reproducing characteristics can be obtained.

  Examples of the present invention will be described below, but the present invention is not limited to these examples.

(Comparative Example 1)
<Preparation of master disc>
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 original plate was dried to prepare a master for producing a magnetic transfer master carrier.

<Preparation of master carrier for magnetic transfer>
A Ni conductive layer having a thickness of 10 nm was formed on the surface of the produced master (patterned silicon substrate) by the sputtering method under the following film forming conditions.
-Ni conductive layer deposition conditions-
-Target material: Ni
・ Film pressure: 0.1 Pa
・ Distance between substrate and target: 100mm
・ DC power: 500W

Next, a metal plate made of Ni having a thickness of 150 μm was formed on the surface of the master by electroforming. Specifically, the current density of the current passed through the electroforming bath is set to 10 to 50 mA while the master on which the conductive layer is formed is immersed in a Ni electroforming bath having the following composition and rotated at a constant rotation speed. The electroforming process was performed at / cm ² .
-Ni electroforming bath composition and temperature-
・ Nickel sulfamate ... 600g / L
・ Boric acid ... 40g / L
・ Surfactant (sodium lauryl sulfate) ... 0.15 g / L
・ PH = 4.0
・ Temperature = 55 ℃

  Next, the metal plate and the conductive layer were peeled from the master (peeling step) and washed to prepare a base material for a magnetic transfer master carrier.

Next, a base thin layer (Pt) having a thickness of 10 nm was formed on the obtained base material by sputtering under the following film forming conditions.
-Pt underlayer deposition conditions-
・ Target material: Pt
・ Film pressure = 0.12 Pa
・ Distance between substrate and target = 75mm
・ DC power = 300W

Next, a CoPt magnetic layer (Co 80 at% -Pt 20 at%) having a thickness of 20 nm was formed on the underlying thin layer by sputtering under the following film forming conditions. Thus, the magnetic transfer master carrier of Comparative Example 1 was produced.
-Film formation conditions for CoPt magnetic layer-
・ Target material: CoPt
・ Film pressure = 0.15 Pa
・ Distance between substrate and target = 200mm
・ DC power = 1000W

  Next, for the magnetic transfer master carrier of Comparative Example 1 produced, the orientation and the transfer medium were evaluated as follows. The results are shown in Table 1.

<Evaluation of orientation>
The orientation was evaluated by X-ray diffraction.
As an X-ray diffractometer, X'Pert Pro (Panalytic) was used, and measurement was performed by the Bragg Brentano method.
As a means for comparing the orientation, the full width at half maximum (Δθ ₅₀ ) of each peak was used. However, since it is difficult to compare in absolute value, it was expressed as a relative value based on Comparative Example 1.
That is, in Comparative Example 1, the Ni surface (111) orientation on the substrate surface after the peeling step (hereinafter abbreviated as Ni (111)) and the c-axis orientation of the CoPt magnetic layer (hereinafter CoPt (002)). And a half value width (Δθ ₅₀ ) of the peak corresponding to the reference value, and the relative value was evaluated.

<Evaluation of transfer medium>
The waveform of the transferred magnetic signal preamble portion was taken into an oscilloscope, and S / N was calculated. As for the S / N value, the average value of 190 frames (bit length = 100 nm) was obtained to minimize the influence of variation.
The S / N values were compared in dB with reference to the transfer product of the magnetic transfer master carrier of Comparative Example 1.

(Examples 1-17)
In Comparative Example 1, the heat treatment step before forming the Ni conductive layer using the clean oven and (2) the heat treatment step after forming the Ni conductive layer using the clean oven shown in Table 1 were performed. The magnetic transfer master carriers of Examples 1 to 17 were produced in the same manner as in Comparative Example 1 except that the thickness of the Pt base thin layer was changed as necessary.
Using each of the obtained magnetic transfer master carriers, the orientation and the transfer medium were evaluated in the same manner as in Comparative Example 1. The results are shown in Table 1.

From the results in Table 1, it is possible to enhance the c-axis orientation of the CoPt magnetic layer simply by forming a thin underlayer on the Ni substrate by performing heat treatment before or after forming the Ni conductive layer. I understood. Furthermore, it was confirmed that the transfer signal quality (S / N) was improved.
In addition, when the base film Pt is thick, the orientation of the CoPt magnetic layer formed on the master is increased, but the total thickness of the magnetic layer (underlayer + magnetic layer) is increased, so the influence of the deterioration of the shape of the magnetic layer It is considered that the magnetic transfer signal is deteriorated (S / N reduction).
It has also been found that forming a thin underlayer as much as possible is effective for improving the quality of the transfer signal.

  The magnetic transfer master carrier produced by the method for producing a magnetic transfer master carrier of the present invention can suppress the deterioration of the shape of the magnetic film formed on the magnetic transfer master carrier as much as possible, and has excellent transfer signal quality. Therefore, it is preferably used for magnetic transfer of a high-density perpendicular magnetic recording medium.

FIG. 1 is an explanatory diagram of a method for manufacturing a master disk according to an embodiment of the present invention. FIG. 2 is an explanatory diagram of a method for manufacturing a master disk according to an embodiment of the present invention. FIG. 3 is an explanatory diagram of a method for manufacturing a master disk according to an embodiment of the present invention. FIG. 4 is a top view of the master disk. FIG. 5 is a partial cross-sectional view of a master disk according to an embodiment of the present invention. FIG. 6 is an explanatory diagram showing the steps of the perpendicular magnetic recording transfer method. FIG. 7 is an explanatory diagram showing a cross section of the slave disk. FIG. 8 is an explanatory diagram showing the magnetization direction of the magnetic layer (recording layer) after the initial magnetization step. FIG. 9 is an explanatory view showing a magnetic transfer process. FIG. 10 is a schematic configuration diagram of a magnetic application device used in the magnetic transfer process. FIG. 11 is an explanatory diagram showing the magnetization direction of the magnetic layer (recording layer) after the magnetic transfer step.

Explanation of symbols

10 Slave disk (perpendicular magnetic recording medium)
20 Master disk (master carrier for magnetic transfer)
30 Original plate (silicon substrate)
36 Master (silicon substrate)
40 Metal plate 42 Master substrate (orientation substrate)
42A Coarse master substrate (base material)
47 Base thin layer 48 Magnetic layer 202, 212 Oriented substrate 204, 214 Magnetic layer

Claims (7)

A method for producing a master carrier for magnetic transfer, comprising an orientation substrate, a base thin layer formed on the orientation base, and a magnetic layer formed on the base thin layer,
A heat treatment step before forming a conductive layer for heat treating the patterned surface of the patterned silicon substrate; and
A conductive layer forming step of forming a Ni conductive layer on the silicon substrate after the heat treatment;
On the silicon substrate having the conductive layer, Ni plating is performed to form a base material;
A peeling step of peeling the base material from the silicon substrate;
A method for producing a master carrier for magnetic transfer, comprising:   The method for producing a master carrier for magnetic transfer according to claim 1, wherein the heat treatment is performed at 300 ° C to 450 ° C for 20 minutes to 40 minutes. A method for producing a master carrier for magnetic transfer, comprising an orientation substrate, a base thin layer formed on the orientation base, and a magnetic layer formed on the base thin layer,
A conductive layer forming step of forming a Ni conductive layer on the patterned silicon substrate;
A heat treatment step after the formation of the conductive layer for heat-treating the surface of the Ni conductive layer;
On the silicon substrate having the conductive layer after the heat treatment, Ni plating is performed to form a base material;
A peeling step of peeling the base material from the silicon substrate;
A method for producing a master carrier for magnetic transfer, comprising:   The method for producing a magnetic transfer master carrier according to claim 3, wherein the heat treatment is performed at 300 to 450 ° C. for 10 to 30 minutes.   5. A magnetic transfer master carrier produced by the method for producing a magnetic transfer master carrier according to claim 1.   6. The master carrier for magnetic transfer according to claim 5, wherein the thickness of the underlying thin layer is 1 nm to 30 nm. An initial magnetization step of initially magnetizing the perpendicular magnetic recording medium in the perpendicular direction;
An adhesion step of closely attaching the magnetic transfer master carrier according to any one of claims 5 to 6 to the perpendicular magnetic recording medium after the initial magnetization step;
A magnetic transfer step of transferring magnetic information to the perpendicular magnetic recording medium by applying a perpendicular magnetic field opposite to the initial magnetization in a state where the perpendicular magnetic recording medium and the magnetic transfer master carrier are in close contact with each other; A magnetic transfer method comprising: