JP5272936B2 - Method for producing patterned media type magnetic recording medium - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for manufacturing a patterned medium type magnetic recording medium which maintains initial magnetic characteristics of an unprocessed magnetic recording medium when a concavo-convex pattern is formed on a surface of the magnetic recording medium to form the patterned medium type magnetic recording medium. <P>SOLUTION: On a surface of a substrate 10, a soft magnetic layer 11, a seed layer 12, an intermediate layer 13, a magnetic layer 14, a second protective layer 17 made of a noble metal material, and a first protective layer 15 made of diamond-like carbon are stacked in this stated order. A predetermined resist 16 pattern is formed on a surface of the first protective layer 15. Thereafter, the first protective layer 15 is selectively removed by oxygen-based dry etching using the resist 16 as a mask to expose the second protective film 17, and the second protective layer 17 and the magnetic layer 14 are selectively removed by inert gas dry etching. Thereafter, the resist 16 is removed, the first protective layer 15 is removed by oxygen dry etching, and the second protective layer 17 is removed by inert gas dry etching. <P>COPYRIGHT: (C)2011,JPO&amp;INPIT

Description

  The present technology relates to a method of manufacturing a patterned media type magnetic recording medium.

  Conventionally, in order to improve the recording density of magnetic recording media such as hard disks, various measures have been taken, such as changing the constituent materials, making the recording layer finer, miniaturizing the head, or perpendicular magnetic recording. The increase in density is reaching its limit. In order to further improve the recording density, a patterned media type magnetic recording medium such as a discrete track type or a bit pattern type in which the magnetic layer is divided by adding a fine uneven pattern to the surface of the magnetic recording layer of the magnetic recording medium. Has been announced.

  FIG. 2 shows a schematic configuration for forming a desired fine concavo-convex pattern on the surface of such a patterned media type magnetic recording layer. With reference to this FIG. 2, the process of forming the conventional uneven | corrugated pattern is demonstrated.

  First, a carbon protective layer is formed on the surface of a magnetic recording medium having a laminate of a soft magnetic layer 11, a crystalline seed layer 12, an intermediate layer 13 such as Ru, and a magnetic recording layer 14 made of a ferromagnetic material layer on a glass substrate 10. 15 is covered with a thick resist 16 made of SOG (Spin On Glass) (FIG. 2A).

Using a stamper (not shown) having a transfer pattern composed of a desired concavo-convex pattern, the concavo-convex pattern is transferred to the resist 16 by the nanoimprint method (FIG. 2B).
The resist 16 is etched by reactive ion etching using a fluorine-based gas, and the thin portion of the resist 16 is removed to expose the underlying carbon protective layer 15 (FIG. 2C).

The carbon protective layer 15 exposed using the remaining resist 16 is etched by reactive ion etching using O ₂ gas (FIG. 2D). The resist 16 covering the carbon protective layer 15 is removed by reactive ion etching using a fluorine-based gas (FIG. 2E).

Using the carbon protective layer 15 as a mask, a groove 18 is formed in the magnetic recording layer 14 by ion beam etching using an inert gas such as Ar (FIG. 2F).
After processing the grooves 18 in the magnetic recording layer 14, the carbon protective layer 15 used as a mask is removed by reactive ion etching with O ₂ gas (FIG. 2 (g)).

  Thereafter, a nonmagnetic material (not shown) is buried in the groove 18 by a CVD method or the like, the nonmagnetic material formed on the upper surface of the convex portion is removed and planarized, and then a protective layer is formed again. Type magnetic recording medium is formed.

  With respect to such a patterned media type magnetic recording medium, a first mask layer, a second mask layer, and a resist layer are formed, and using these as a mask, an uneven pattern is formed on the continuous recording layer by etching. Description can be seen (Patent Document 1).

Japanese Patent Laying-Open No. 2005-50468 (Claim 1)

In the conventional method for producing a patterned media type magnetic recording medium, in order to peel off the carbon protective layer 15, it is effective that the etching selectivity with the magnetic recording layer (magnetic layer) 14 is large. Reactive ion etching with ₂ gas or O ₃ gas is used.

However, according to the reactive ion etching of O ₂ gas or O ₃ gas, the etching to the magnetic recording layer 14 does not proceed substantially, but on the surface of the magnetic recording layer 14 in contact with the O ₂ gas or O ₃ gas. It is inevitable that existing Co or Cr is oxidized.

  The oxidation of the surface of the magnetic recording layer 14 is the diffusion of oxygen atoms or oxygen ions into the magnetic layer and the bonding reaction (oxidation) of oxygen atoms. Therefore, even if oxidized, the degree of oxidation decreases in the depth direction along with the rapid decrease of oxygen atoms and the oxidation rate decreases. Therefore, the entire patterned convex magnetic recording layer is oxidized during etching. There is virtually no such thing.

  However, since the thickness of the formed oxide layer is the same as the fact that the convex portion of the magnetic recording layer is substantially reduced, the problem of a decrease in signal intensity due to the oxidation occurs. This problem can be countered against the oxidation from the side surface of the convex magnetic recording layer by forming a pattern having a wide convex shape in advance by the thickness of the oxide layer to be formed.

  Further, the oxide layer formed on the upper surface of the convex magnetic recording layer has a problem that the thickness of the oxide layer increases the spacing loss with respect to the magnetic head when incorporated in a hard disk drive.

  Therefore, it is conceivable to perform ion etching using an inert gas such as Ar after the carbon protective layer serving as a mask is removed to remove the above-mentioned oxide layer. However, the characteristics of the magnetic recording medium are as follows. Since it is influenced by the thickness, deterioration of the magnetic characteristics due to the thin magnetic recording layer corresponding to the oxide layer is inevitable.

  In addition, the thickness of the oxide layer to be removed is assumed in advance, the magnetic recording layer is formed thicker by that amount, and the oxide layer is removed by dry etching using Ar gas to obtain the designed thickness. And magnetic properties are not the same. Moreover, since it is difficult to control the thickness by dry etching, there is a problem that it is difficult to obtain good magnetic characteristics with good reproducibility.

  The present invention has been made in view of the above points, and an object of the present invention is to manufacture a patterned media type magnetic recording medium by applying a concavo-convex pattern processing to the surface of the magnetic recording medium. It is an object of the present invention to provide a method of manufacturing a patterned media type magnetic recording medium that can maintain the initial magnetic characteristics of the magnetic recording medium without deteriorating.

The present invention, on the substrate surface, a soft magnetic layer, a seed layer to control the crystal orientation of the upper intermediate layer, and an intermediate layer for controlling the magnetic domain orientation of the magnetic recording layer, a magnetic layer comprising a magnetic recording layer, Pt , A step of laminating and forming a second protective layer using at least one selected from Ir, Rh and Pd and a first protective layer mainly composed of diamond-like carbon in this order, and required on the surface of the first protective layer A step of exposing the second protective layer by selectively removing the first protective layer by oxygen-based dry etching using the patterned resist as a mask after forming the resist having the pattern of And selectively removing the layer and the lower magnetic layer by inert gas dry etching, and then removing the resist, and removing the first protective layer exposed by removing the resist from A method of manufacturing a patterned media type magnetic recording medium having at least in this order a step of peeling off the second protective layer exposed by peeling of the first protective layer by dry etching using an inert gas. Thus, the object of the invention is achieved.

In the present invention, it is desirable that the thickness of the second protective layer is 5 nm or less.

In the present invention, it is preferable that the resist is a resist made of SOG.
In the present invention, it is recommended that the resist pattern made of SOG is formed by a nanoimprint method.

In the present invention, the resist made of SOG is more preferably removed by reactive ion etching using a fluorine-based gas.
In the present invention, the inert gas-based dry etching is more preferably ion beam etching using Ar gas.

In the present invention, the oxygen-based dry etching is more preferably reactive ion etching using O ₂ gas O ₃ gas.

  According to the present invention, when a patterned media type magnetic recording medium is manufactured by applying a concavo-convex pattern processing to the surface of the magnetic recording medium, the patterned magnetic layer that maintains the initial magnetic characteristics of the magnetic recording medium before processing without deteriorating. A method of manufacturing a media type magnetic recording medium can be provided

It is a schematic sectional drawing of the board | substrate which shows the uneven | corrugated pattern formation process in the patterned media type magnetic recording medium as described in Example 1 of this invention. It is a schematic sectional drawing of the board | substrate which shows the uneven | corrugated pattern formation process in the conventional patterned media type magnetic recording medium.

  Embodiments of a method for manufacturing a patterned media type magnetic recording medium of the present invention will be described in detail below with reference to the drawings. The present invention is not limited to the description of the examples described below unless it exceeds the gist.

Hereinafter, a first embodiment according to a method for manufacturing a patterned media type magnetic recording medium of the present invention will be described with reference to the drawings.
FIG. 1 is a schematic cross-sectional view of a substrate showing a concavo-convex pattern forming step in order to explain the method for producing a patterned media type magnetic recording medium of the present invention.

In the magnetic recording medium according to the present invention, a glass substrate is used as the substrate 10. However, a substrate whose main material is aluminum or silicon is also possible.
A soft magnetic layer 11 having a thickness of 5 to 100 nm is formed on the substrate 10 by sputtering a soft magnetic material containing at least one of Co, Ni, Fe and the like. Specifically, the soft magnetic layer 11 made of CoZrNb is formed to a thickness of 45 nm.

  Next, in order to control the crystal orientation of Ru or the like serving as an intermediate layer on the surface of the soft magnetic layer 11, a crystalline seed layer 12 is formed by sputtering with a thickness of 10 nm or less. Specifically, the seed layer 12 made of CoNiFeSi is formed to a thickness of 5 nm. Subsequently, Ru or the like to be the intermediate layer 13 is formed with a thickness of 1 to 10 nm by a sputtering method. Specifically, Ru is formed to a thickness of 10 nm.

Thereafter, a ferromagnetic material containing at least one of Co, Cr, Pt, Ni, Fe and the like to be the magnetic recording layer 14 is formed with a thickness of 5 to 50 nm by a sputtering method or the like. Specifically, a granular layer (not shown) made of CoCrPt—SiO ₂ is formed to a thickness of 8 nm, a Ru layer (not shown) is formed to a thickness of 0.2 nm, and a CoCrPtB layer (not shown) is formed. To be perpendicular magnetic recording layer 14 having a thickness of 8 nm.

  Thereafter, at least one kind of noble metal material is formed as a noble metal thin film layer 17 with a thickness of 0.1 to 5 nm by sputtering or the like from Au, Pt, Ir, Rh and Pd. The film is preferably formed with a thickness of 1 to 2 nm.

  Next, carbon such as DLC (Diamond Like Carbon) is formed as a first protective layer with a thickness of 10 nm to 30 nm by a CVD (Chemical Vapor Deposition) method to form the DLC film 15. The DLC film 15 is used as an etching mask when forming an uneven pattern on the magnetic recording layer 14. Since the pitch width of the concavo-convex pattern formed on the surface of the magnetic recording layer 14 is affected by the thickness of the mask thereon, the film thickness of the DLC film 15 as a mask is equal to the assumed surface concavo-convex pattern of the magnetic recording layer 14. It is determined in consideration of the pitch width.

  Next, in order to pattern-process the DLC film 15 formed in the thickness determined as described above, the thickness of the mask of the resist 16 formed on the surface of the DLC film 15 is also the same as the surface uneven pattern. It is determined in consideration of the pitch width (FIG. 1 (a)). As the resist 16, SOG (Spin On Glass) is applied to the surface of the DLC film 15 with a thickness of 50 to 200 nm by spin coating or spray coating.

  Separately, SOG (Spin) applied to the surface of the DLC film 15 by a nanoimprint method using a stamper in which Ni, silicon, glass or the like is used as a base material, and a concavo-convex pattern having the pitch width is formed on the surface thereof. The concavo-convex pattern is transferred to the resist 16 made of On Glass (FIG. 1B).

  For the resist 16, it is also possible to use a resin material such as an ultraviolet curable type, a thermoplastic, or a thermosetting type mainly composed of an acrylic resin. Since the resist 16 serves as a mask for forming an uneven pattern in the underlying DLC film 15 by etching, it is necessary to select a resist 16 having a high selective etching rate with respect to the DLC film 15. A resist made of SOG is a resist suitable for that purpose.

When the DLC film 15 is used as a mask layer for etching a concavo-convex pattern on the magnetic recording layer, it is effective to perform etching with O ₂ gas plasma from the viewpoint of etching selectivity. In this case, since a resist of a normal resin material cannot provide effective etching selectivity with respect to the DLC film 15, it is desirable to use SOG having selectivity as the resist.

  The concavo-convex pattern formed on the stamper used in the nanoimprint method can improve the storage density by forming the pattern pitch as small as possible using a lithography technique using an electron beam lithography apparatus. This pattern pitch depends on the performance of the electron beam drawing apparatus.

  In the concavo-convex pattern transferred to the resist 16 made of SOG by the nanoimprint method, the remaining film thickness of the resist 16 made of SOG can be formed between the surface of the DLC film 15 also in the resist concave portion. In the nanoimprint method, it is difficult to completely eliminate the thickness of the remaining film, and as the thickness is reduced, the thickness of the remaining film becomes non-uniform in the substrate surface, so that accurate processing in the substrate surface becomes difficult. The remaining film thickness between the resist concave layer and the surface of the DLC film 15 is set to 1/3 to 2/3 of the resist coating thickness so that the remaining film thickness can be made uniform within the substrate surface. (FIG. 1 (b)).

The remaining film portion of the resist 16 made of SOG is removed by reactive ion etching using a fluorine-based gas to expose the surface of the DLC film 15 (FIG. 1C).
At this time, since the convex portion of the resist 16 is also etched by fluorine-based gas ions, when etching with fluorine-based gas ions, the anisotropy of ions is increased by applying a substrate bias or by a grid electrode, and as perpendicular to the substrate as possible. Ions are preferably incident. Specifically, using CF ₄ gas, RF is generated with a power of 100 W to 1000 W, and a substrate bias is applied with a power of 10 W to 200 W, or a voltage of 100 V to 2000 V is applied to the grid electrode. (FIG. 1C).

Next, using the remaining convex portion of the resist 16 as a mask, the DLC film 15 is selected by reactive ion etching using O ₂ gas until the surface of the noble metal thin film layer 17 serving as the second protective layer is exposed. To remove. At this time, the anisotropy of oxygen ions is controlled by the substrate bias or the grid electrode, and the concave side wall taper angle formed in the DLC film 15 is arbitrarily formed, so that the concave portion is formed with respect to the width of the opening at the top of the concave portion. The width of the exposed surface of the noble metal thin film layer 17 at the bottom can be arbitrarily reduced.

Further, the anisotropy of oxygen ions can be controlled by controlling the pressure during the etching process. In addition, the resist 16 made of oxygen ions and SOG is poor in reactivity, and the resist 16 as a mask is only subject to physical etching, so that the reduction in the width of the convex resist is small. Specifically, using O ₂ gas, RF is generated at a power of 100 W to 1000 W, and a substrate bias is applied at a power of 10 W to 200 W, or an ion acceleration voltage of 100 V to 2000 V is applied to the grid electrode. Then, the DLC film 15 is etched (FIG. 1D).

After the DLC film 15 is processed, the resist 16 made of SOG is removed by reactive ion etching using a fluorine-based gas (FIG. 1E).
Thereafter, using the DLC film 15 as an etching mask, the noble metal thin film layer 17 and the magnetic recording layer 14 are processed by ion beam etching using an inert gas such as Ar gas. At this time, the noble metal thin film layer 17 is easy to process since it has a high sputtering rate and a high etching rate with respect to an inert gas such as Ar gas (FIG. 1 (f)).

After the noble metal thin film layer 17 and the magnetic recording layer 14 are etched, the DLC film 15 as an etching mask is removed by reactive ion etching using O ₂ gas (FIG. 1 (g)).

  At this time, since the noble metal thin film layer 17 is left and only the DLC film 15 is removed, it is necessary to suppress physical etching of oxygen ions or oxygen radicals. Therefore, ions are not accelerated by the substrate bias or the grid electrode, only the RF discharge is performed, and the pressure is set high in order to weaken the anisotropy of oxygen ions or oxygen radicals.

Specifically, the DLC film 15 is removed by using O ₂ gas to generate a plasma with a pressure of 1 Pa to 5 Pa and RF of 100 W to 1000 W. As a result, the DLC film 15 is removed without oxidizing the surface of the noble metal thin film layer 17, and the noble metal thin film layer 17 remains. Can be maintained (FIG. 1 (g)).

After removing the DLC film 15, the noble metal thin film layer 17 is removed by ion beam etching using an inert gas such as Ar gas (FIG. 1 (h)).
At this time, it is necessary to remove only the noble metal thin film layer 17 by etching without etching the magnetic recording layer 14. Therefore, only the noble metal thin film layer 17 is etched by making it weaker than the beam intensity in the ion beam etching at the time of performing the uneven processing of the magnetic recording layer 14. Specifically, only the noble metal thin film layer 17 is removed by applying an ion acceleration voltage of 50 V to 500 V to the grid electrode at a pressure of 6 × 10 ⁻² Pa or less using Ar gas.

  As a result, a concavo-convex structure without damage is formed on the convex surface of the magnetic recording layer 14. Thereafter, the steps after the step of filling the recesses of the magnetic recording layer 14 with a nonmagnetic material and flattening are the same as the conventional steps.

  As described above, according to the method for manufacturing the patterned media type magnetic recording medium described in the first embodiment, the magnetic recording layer is substantially formed of an oxide layer as compared with the initial magnetic layer thickness or design thickness. Therefore, the initial magnetic characteristics of the magnetic recording medium before processing can be maintained without deteriorating.

DESCRIPTION OF SYMBOLS 10 Substrate 11 Soft magnetic layer 12 Seed layer 13 Intermediate layer 14 Magnetic recording layer, magnetic layer 15 Carbon protective layer, DLC film 16 Resist 17 Precious metal thin film layer 18 Groove

Claims (7)

On the surface of the substrate, a soft magnetic layer, a seed layer for controlling the crystal orientation of the upper intermediate layer, an intermediate layer for controlling the magnetic domain orientation of the magnetic recording layer, a magnetic layer to be the magnetic recording layer, Pt, Ir, Rh And a step of laminating and forming a second protective layer using at least one selected from Pd and a first protective layer mainly composed of diamond-like carbon in this order, and having a required pattern on the surface of the first protective layer After forming the resist, using the patterned resist as a mask, the first protective layer is selectively removed by oxygen-based dry etching to expose the second protective layer, and the exposed second protective layer and lower layer After selectively removing the magnetic layer by inert gas dry etching, the resist is removed, and the first protective layer exposed by removing the resist is removed from the oxygen dry etch. A patterned media type magnetic recording comprising: a step of peeling off the second protective layer exposed by peeling of the first protective layer by a dry etching using an inert gas. A method for manufacturing a medium. The method for producing a patterned media type magnetic recording medium according to claim 1, wherein the thickness of the second protective layer is 5 nm or less. Method for manufacturing a patterned magnetic recording medium according to any one of claims 1 to 2, wherein the resist is a resist made of SOG. 4. The method of manufacturing a patterned media type magnetic recording medium according to claim 3, wherein the resist pattern made of SOG is formed by a nanoimprint method. 5. The method of manufacturing a patterned media type magnetic recording medium according to claim 4, wherein the resist made of SOG is removed by reactive ion etching using a fluorine-based gas. 2. The method of manufacturing a patterned media type magnetic recording medium according to claim 1, wherein the inert gas based dry etching is ion beam etching using Ar gas. _{2. The} method of manufacturing a patterned media type magnetic recording medium according to claim 1, wherein the oxygen-based dry etching is reactive ion etching using O ₂ gas O ₃ gas.

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