JP2010061722A - Method of manufacturing substrate, substrate manufactured by the method, and magnetic recording medium using the substrate - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method of manufacturing a substrate having a projecting part of a desired shape and high flatness with ease and high accuracy at a high throughput. <P>SOLUTION: In the manufacturing method includes steps of: applying a solution formed by dissolving a structural material which constitutes a projecting part in a solvent on a substrate base material provided with a sacrifice layer in which a recessed part is formed to fill the recessed part with the solution; drying the solvent of the solution filled in the recessed part to form the projecting part; and removing the sacrifice layer so that the projecting part remains. A contact angle θ of the sacrifice layer to the solution is <90°. A value d determined by L×(1-sinθ)/(2cosθ) is <10 nm when the minimum distance between side surfaces of the recessed part passing through the center of gravity of the cross section parallel to the surface of the substrate base material is L. The smaller one of the distance between the position farthest from the substrate base material and the surface of the substrate base material when the recessed part is filled with the solution, and the depth of the recessed part, is d or larger. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a substrate manufacturing method, a substrate manufactured by the method, and a magnetic recording medium using the substrate.

  As a magnetic recording medium, patterned media (PM) has been proposed in which a magnetic layer is patterned and the magnetic layer is physically divided into a plurality of regions in order to further increase the recording density. As a method for producing this PM, for example, a method of forming a pattern by a nanoimprint method has been proposed. In the nanoimprint method, first, the uneven shape of the mold is transferred to the imprint material by pressing a mold having an uneven shape on the surface against the imprint material applied on the substrate substrate, and the uneven shape is transferred. This is a method of obtaining a substrate having a concavo-convex shape on the surface by peeling the mold after solidifying the imprint material. For example, the method of patent document 1 and patent document 2 is mentioned.

  Patent Document 1 discloses a step of forming a transfer target (imprint material layer) on a flat substrate or a mold having a concavo-convex structure, a step of bringing the mold into contact with the transfer target and pressurizing, and the mold. A step of transferring the concavo-convex structure to the transferred body, a step of peeling the mold from the transferred body, and a step of depositing a magnetic recording layer on the transferred body onto which the concavo-convex structure of the mold is transferred. A method of manufacturing a magnetic recording medium is described.

  Patent Document 2 discloses a step of forming a base having a dot-shaped convex portion corresponding to a dot-shaped concave portion of a stamper (template) on the surface, and a ferromagnetic material on the surface of the base provided with the dot-shaped convex portion. And a method of manufacturing a recording medium including a step of forming a layer (magnetic layer) containing the.

  Moreover, as a method for forming a fine structure by filling magnetic particles into a concave portion having a fine concavo-convex shape formed in advance, for example, a method described in Patent Document 3 can be mentioned.

Patent Document 3 discloses a method of manufacturing a disk-shaped magnetic recording medium having a soft magnetic layer, a magnetic recording layer thereabove, and an intermediate layer directly under the magnetic recording layer, the upper surface of the intermediate layer Describes a method for manufacturing a magnetic recording medium, which includes providing a concave portion and a convex portion that repeat irregularities in the radial direction of the disk, and filling the concave portion with magnetic particles in a self-organized manner.
JP 2007-95162 A JP 2004-303302 A JP 2007-220196 A

  According to the nanoimprint method as described in Patent Document 1 and Patent Document 2, for example, an uneven shape can be formed under atmospheric pressure, and a process of evacuating the apparatus is not particularly required. A substrate having a shape and the like can be manufactured easily and with high throughput.

  However, according to the method described in Patent Document 1, it may be difficult to form a desired uneven shape depending on the imprint material. For example, when a spin-on-glass material (SOG) is used as the imprint material, when the solvent in the SOG is dried, the imprint material becomes vitreous and hardens. If the imprint material becomes too hard before pressing the mold, the pressure for pressing the mold is insufficient, the transferability becomes insufficient, and the desired uneven shape cannot be formed. was there. Further, when the pressure to be pressed is increased in order to improve transferability, the mold may be damaged. On the other hand, when the shape of the mold is transferred by pressing the mold while the solvent in the SOG is insufficiently dried, the SOG is sandwiched between the mold and the substrate during the transfer. Since the area in contact with air is very small, the SOG is difficult to dry. For this reason, when the mold is released, it takes time to cure the SOG to such an extent that the shape can be maintained, which hinders high throughput.

  Further, according to the method described in Patent Document 2, since a liquid imprint material is applied onto a mold and dried as it is to form a substrate, the imprint material can be easily dried even during transfer. However, since the surface of the substrate that is not in contact with the mold is in an open state, waviness or the like is generated on the surface and the flatness is sometimes low. In such a case, when the substrate is released from the mold, low flatness such as waviness on the surface of the substrate that is not in contact with the mold may affect the surface to which the uneven shape is transferred. For example, if it is attached to a substrate substrate with high flatness, the waviness of the surface that is not in contact with the mold of the substrate may follow the surface to which the concavo-convex shape is transferred, resulting in low flatness. It was.

  On the other hand, in a magnetic recording device such as a hard disk drive, the magnetic head is separated from the surface of the rotating magnetic recording medium by, for example, about 10 nm when recording information on the magnetic recording medium or reading the recorded information. ing. Accordingly, when a magnetic recording medium obtained by forming a magnetic layer or the like on the surface of a substrate having inferior shape transferability or inferior flatness of the surface to which the uneven shape is transferred, as described above, There is a problem that a head crash occurs when the head contacts the magnetic recording medium. Further, when manufacturing a magnetic recording medium, as described in Patent Document 2, after a magnetic layer having a desired shape is formed, SOG or the like is applied, and a nonmagnetic film made of SOG or the like is provided between the magnetic layers. It is also possible to form a film and then etch back to obtain a uniform surface. However, even if the surface is made uniform in this way, head crush may occur when a substrate having inferior shape transferability, flatness of the surface to which the uneven shape is transferred, etc. is used. In addition, when etch back is performed, there is a problem that high throughput is hindered. For example, when dry etching is used when performing etch back, the inside of the etching apparatus must be evacuated, which hinders high throughput.

  Further, according to Patent Document 3, magnetic particles can be filled only in a fine concave-convex recess formed in advance by spin coating or the like. It is considered that a fine uneven shape can be formed by using a structural material such as the imprint material in place of the magnetic particles and removing a previously formed fine uneven shape as a sacrificial layer. However, when a liquid material such as SOG is used instead of magnetic particles to form a fine uneven shape, even if the liquid material is filled only in the recess, the surface tension of the liquid material, etc. As a result, a so-called meniscus in which the liquid material rises or sinks near the wall surface of the recess is generated. Due to this meniscus, it is difficult to sufficiently improve the flatness of the surface to which the concavo-convex shape is transferred, and there is a possibility that a head crash may occur.

  The present invention has been made in view of such circumstances, and a head having a plurality of convex portions having a desired shape and having a high flatness, for example, a magnetic layer or the like on the surface is used as a magnetic recording medium. It is an object of the present invention to provide a manufacturing method capable of manufacturing a substrate with high flatness that suppresses the occurrence of a crash with high accuracy with a simple and high throughput. It is another object of the present invention to provide a substrate manufactured by the manufacturing method and a magnetic recording medium using the substrate.

  A method for manufacturing a substrate according to an aspect of the present invention is a method for manufacturing a substrate having a plurality of convex portions, on a substrate base material provided with a sacrificial layer in which concave portions corresponding to the convex portions are formed. The step of filling the concave portion with the solution by applying a solution in which the structural material constituting the convex portion is dissolved in a solvent, and the step of drying the solvent of the solution filled in the concave portion. A step of forming a portion, and a step of removing the sacrificial layer so as to leave the convex portion, and a contact angle θ of the sacrificial layer with respect to the solution is less than 90 °, The value d determined by L × (1-sin θ) / (2 cos θ) is less than 10 nm, where L is the minimum distance between the side surfaces passing through the center of gravity in the cross section parallel to the surface of the substrate base material, When the recess is filled with the solution, The distance between the position farthest from the substrate base material of the solution and the surface of the substrate base material, and the smaller length of the depth of the concave portion is not less than d.

  According to the above configuration, a substrate having a plurality of convex portions having a desired shape and having high flatness can be easily manufactured with high accuracy and high throughput. This is considered to be due to the following.

  First, since the contact angle θ of the sacrificial layer with respect to the solution is less than 90 °, the concave portion of the sacrificial layer can be sufficiently filled with the solution before drying. When the distance L between the side surfaces of the recesses is such that the value d determined by L × (1-sin θ) / (2 cos θ) is less than 10 nm, the solution filled in the recesses Even if meniscus is generated on the surface, it is considered that the flatness of the obtained convex portion is sufficiently high. Therefore, the flatness of the surface on which a plurality of convex portions are formed is not greatly reduced, and a substrate with excellent flatness can be easily manufactured with high throughput and high accuracy without performing a special process. Further, when the surface of the solution filled in the concave portion is close to the substrate base material, the solution is affected by the substrate base material, and the shape of the solution depends on the application conditions of the solution such as the number of spin coat rotations. It depends on. Therefore, the distance between the position farthest from the substrate base material of the solution and the surface of the substrate base material, and the smaller length of the depth of the recess satisfy the d or more. By adjusting to the amount of the solution filled in the recess, etc., a substrate with high flatness can be manufactured without being affected by the coating conditions.

  The structural material is a silicon compound, the solvent is at least one selected from ethers and alcohols, and the sacrificial layer is selected from the group consisting of acrylic resins, epoxy resins, and phenolic resins. It is preferable that it is at least one kind. According to the combination as described above, the contact angle θ of the sacrificial layer with respect to the solution can be realized to be less than 90 °, and a substrate having a plurality of convex portions with higher flatness and a desired shape can be easily and with high throughput. It can be manufactured with high accuracy.

  It is preferable that the convex portion has a cylindrical shape. According to this configuration, a substrate having higher flatness and having a plurality of convex portions having a desired shape can be manufactured more easily, with high throughput, and with high accuracy. The obtained substrate is more suitable as a substrate for PM.

  A substrate according to another embodiment of the present invention is obtained by the manufacturing method. According to said structure, the board | substrate which has multiple convex parts of desired shape and has high flatness is obtained. For example, when a magnetic recording medium is provided by providing a magnetic layer or the like on the surface, a substrate that can produce a highly flat substrate that suppresses the occurrence of head crashes can be obtained.

  A magnetic recording medium according to another aspect of the present invention includes the substrate and a magnetic layer provided on the substrate, and the magnetic layer is formed on a convex portion of the substrate. And a magnetic layer formed on the substrate substrate are regularly arranged. According to said structure, the magnetic recording medium with high flatness which can suppress generation | occurrence | production of a head crash is obtained.

  According to the present invention, it is possible to provide a manufacturing method capable of manufacturing a substrate having a plurality of convex portions having a desired shape and having high flatness easily and with high throughput and high accuracy. Further, a substrate manufactured by such a substrate manufacturing method and a magnetic recording medium using the substrate are provided.

  Hereinafter, although the embodiment concerning the manufacturing method of the substrate of the present invention is described, the present invention is not limited to these.

  The substrate manufacturing method according to the present embodiment is a method for manufacturing a substrate having a plurality of convex portions. Specifically, the structural material constituting the convex portion was dissolved in a solvent on the substrate base 11 provided with the sacrificial layer 12 in which the concave portion 13 corresponding to the convex portion as shown in FIG. 1 was formed. The step of filling the recess with the solution by applying a solution, the step of forming the projection by drying the solvent of the solution filled in the recess, and the projection remaining. Removing the sacrificial layer. By such a process, a substrate having a plurality of convex portions can be manufactured. FIG. 1 is a bird's-eye view showing an example of the substrate base 11 provided with the sacrificial layer 12 used in the substrate manufacturing method according to the present embodiment, and shows a part of the substrate base 11. Here, the concave portion 13 is described by taking a cylindrical shape, but is not limited to a cylindrical shape, and may be a polygonal columnar shape such as a quadrangular columnar shape or a hexagonal columnar shape, and extends in a specific direction. It may be groove-shaped. Moreover, when the said board | substrate base material 11 is disk shape, the groove shape extended in the circumferential direction of the said board | substrate base material 11 may be sufficient.

  Further, the substrate manufactured here may be any substrate having a plurality of convex portions on the surface, and examples thereof include a substrate for a patterned magnetic recording medium (patterned media: PM). Moreover, as said convex part, it is a fine convex part, for example, a convex part of nm order etc. are mentioned.

  Then, the sacrificial layer and the kind and shape of the solution satisfy the following relationship as shown in FIGS. FIG. 2 is a top view of the substrate base material 11 in a state where the recess 13 of the sacrificial layer 12 is filled with the solution, as viewed from above the opening of the recess 13. FIG. 3 is a schematic cross-sectional view of the substrate base material 11 shown in FIG. 2 as viewed from the cutting plane line III-III ′.

  First, as shown in FIG. 3, the contact angle θ of the sacrificial layer 12 with respect to the solution 14 is less than 90 °. If such a relationship is satisfied, the solution 14 before drying can be sufficiently filled in the concave portion 13 of the sacrificial increase 12 provided in the substrate base material 11. This is considered to be due to the following. When the contact angle θ of the sacrificial layer 12 with respect to the solution 14 is less than 90 °, the state is generally said to be immersion wet, and the solution 14 is well wet spread over the sacrificial layer 11. Therefore, it is considered that the filling property of the solution 14 can be sufficiently improved. Since the main component of the solution 14 is the solvent before the solvent is dried, the contact angle θ of the sacrificial layer 12 with respect to the solution 14 is substantially equal to the contact angle θ of the sacrificial layer 12 with respect to the solvent. It is considered that the filling property of the solution 14 into the concave portion 13 of the sacrificial layer 12 can be changed by the properties of the sacrificial layer 12 and the solvent. Further, in such a state of immersion wetting, the wettability is further enhanced if the application surface of the solution is slightly roughened. For example, when a 2.5-inch substrate generally used as a magnetic recording medium is used as the substrate base material 11, the substrate base material 11 has a donut shape with an outer diameter of 65 mm and an inner diameter of 20 mm, and is magnetic for PM. In order to obtain a recording medium, the distance between the centers of the adjacent concave portions 13 of the sacrificial layer 12 is as large as several tens of nanometers, which corresponds to a state in which the coated surface is slightly roughened. Further, the wettability is further improved, so that the filling property is further increased. For this reason, even if the area of a board | substrate base material is large, it is suitable also at the point that favorable filling property can be ensured.

  As shown in FIGS. 2 and 3, when L is the minimum distance between the side surfaces of the recess 13 passing through the center of gravity in the cross section parallel to the surface of the substrate base 11, L × (1-sin θ ) / (2 cos θ), the value d is less than 10 nm. Here, L corresponds to the diameter because the concave portion 13 is cylindrical. By setting L so as to satisfy such a relationship, even if meniscus is generated on the surface of the solution 14 filled in the concave portion 13, the flatness of the obtained convex portion is considered to be sufficiently high. It is done.

  Hereinafter, in order to explain the reason why this high flatness is obtained, first, the shape of the meniscus, which is the shape of the surface of the liquid, will be described.

  The shape of the surface of the liquid is generally determined by the surface tension and gravity of the liquid. The pressure inside and outside the liquid in the portion where the meniscus is formed has a pressure difference corresponding to the pressure of Laplace pressure due to the influence of surface tension. That is, the shape of the meniscus is determined by the balance between the Laplace pressure and the fluid pressure due to gravity. For example, when liquid is filled in a recess or the like, if the size of the recess is smaller than a size defined by a length called a capillary length, the Laplace pressure is always greater than the hydraulic pressure. In such a case, the meniscus has a constant curvature.

  Here, the case where SOG is filled as the solution 14 in the cylindrical recess 13 of the sacrificial layer 12 as shown in FIG. 1 will be described. In addition, if the said relationship is satisfy | filled, it is not limited to the shape of the recessed part 13 here or the said solution 14. FIG.

In this case, the capillary length κ ⁻¹ can be expressed by the following formula (1).

κ ⁻¹ = (2γ / ρg) ^1/2 (1)
Here, γ represents the surface tension of the liquid, ρ represents the density of the liquid, and g represents the gravitational acceleration. And since the surface tension of the general organic solvent used for SOG is about 25 mN / m and a density is about 0.9 g / cm < ³ >, capillary length (kappa) ^-1 is 2 mm from said Formula (1). Degree. When the diameter of the concave portion 13 is smaller than the capillary length κ- ¹ , the shape of the meniscus becomes a shape with a constant curvature. Therefore, in the case of a substrate used for a magnetic recording medium, for example, a substrate for PM, the diameter of the convex portion corresponding to the concave portion 13 is far smaller than the capillary length κ ⁻¹ and is several tens of nm or less. For this reason, the meniscus shape, which is the shape of the surface of the solution 14 filled in the concave portion 13, becomes a shape with a constant curvature and a shape obtained by cutting off a part of the sphere, as shown in FIG. Further, since the contact angle θ of the solution 14 to the solution of the sacrificial layer 12 is less than 90 °, the contact angle θ of the recess 13 to the solution of the solution 14 is as shown in FIG. It is less than 90 °.

  A value d determined by L × (1−sin θ) / (2 cos θ) where L is a minimum distance between side surfaces passing through the center of gravity in a cross section parallel to the surface of the substrate base material of the recess. The amount of depression of the meniscus that is the distance between the position of the solution 14 farthest from the substrate base 11 and the position of the solution 14 closest to the substrate base 11 is substantially the same. Therefore, when the distance L between the side surfaces of the recesses is such that the value d determined by L × (1-sin θ) / (2 cos θ) is less than 10 nm, the solution filled in the recesses Even if a meniscus is generated on the surface, the flatness of the obtained protrusion is considered to be sufficiently high so as not to cause a head crash when used in a hard disk device.

  As shown in FIG. 4, when the concave portion 13 is filled with the solution 14, the distance between the position farthest from the substrate base material 11 of the solution 14 and the surface of the substrate base material 11, and the concave portion If the smaller length h of the 13 depths is equal to or greater than d, a substrate with high flatness can be manufactured without being affected by the coating conditions. On the other hand, as shown in FIG. 5, when the concave portion 13 is filled with the solution 14, the distance between the position of the solution 14 farthest from the substrate base material 11 and the surface of the substrate base material 11, When the smaller length h of the depths of the recesses 13 is less than the d, the surface of the solution 14 filled in the recesses 13 is close to the substrate base material 11, and the substrate base It will be affected by the material 11. Therefore, the shape of the solution 14 changes depending on the application conditions of the solution 14 such as the number of spin coating revolutions. FIG. 4 shows a cross-sectional view when h is d or more when the recess 13 of the sacrificial layer 12 is filled with the solution. FIG. 5 shows a cross-sectional view when h is less than d when the recess 13 of the sacrificial layer 12 is filled with the solution.

  Therefore, the distance h between the position farthest from the substrate base material 11 of the solution 14 and the surface of the substrate base material 11, and the smaller length h of the depth of the recess 13 is equal to or greater than d. As described above, by adjusting the amount of the solution filled in the concave portion, a substrate with high flatness can be manufactured without being affected by the coating conditions.

  From the above, if each of the above-described configurations is satisfied, a substrate having a plurality of convex portions having a desired shape and high flatness can be easily manufactured with high accuracy and high throughput. In addition, when a magnetic recording medium is provided by providing a magnetic layer or the like on the surface, it is possible to obtain a substrate that can be manufactured with high flatness that suppresses the occurrence of head crash. Such a substrate manufacturing method is particularly suitable for a method for manufacturing a PM substrate or the like that requires extremely high flatness.

  Hereinafter, a method for manufacturing a substrate according to the present embodiment will be described.

  First, a substrate base 11 provided with a sacrificial layer 12 having a plurality of recesses 13 as shown in FIG. 1 is prepared. The method for producing the sacrificial layer having a plurality of such recesses is not particularly limited, and examples thereof include the following methods. First, a layer made of a material constituting the sacrificial layer is formed by a spin coating method, a dip coating method, or the like, and an electron beam drawing (electron beam lithography) method, a photolithography method, a nanoimprint method, or the like is performed on the layer. A plurality of recesses are formed. Thereafter, if necessary, etching is performed in the recess until the substrate base material surface is exposed. By doing so, a substrate substrate provided with a sacrificial layer having a plurality of recesses is obtained.

  Next, the solution is applied on the surface of the substrate base on the side provided with the sacrificial layer. The application method is not particularly limited as long as the concave portion can be filled with the solution, and a known application method can be used. For example, it may be a drop application by a dispenser, a spin coating method, a dip coating method, or the like, or may be spread using a wire bar, an applicator, or the like. At that time, the kind and shape of the sacrificial layer and the kind and amount of the solution are adjusted so that the contact angles θ, d, and h satisfy the above relationships. Moreover, in order to fill the said recessed part with the said solution, you may adjust the density | concentration of the said solution, and in the case of a spin coat method, you may adjust the rotation speed. In addition, it is preferable that the rotation speed in a spin coat method is 1000-10000 rpm, for example.

  The combination of the sacrificial layer, the structural material, and the solvent is not particularly limited as long as the contact angle θ and the like satisfy the above relationship. For example, it is preferable that the sacrificial layer is a resin, the solvent is an organic solvent, and the structural material is an inorganic material.

  Examples of the resin include polyolefin resins, polystyrene resins, acrylic resins, epoxy resins, and phenol resins. Moreover, as said polyolefin resin, cycloolefin resin etc. are mentioned, for example. Examples of the polystyrene-based resin include those used as an electron beam resist resin. Examples of the acrylic resin include those used as ultraviolet curable resins. When the sacrificial layer is used as an electron beam resist, an electron beam drawing method can be used to form the recess, and when an ultraviolet curable resin is used, An optical imprint method can be used to form the recess.

  Examples of the organic solvent include ketones, ethers, alcohols, and esters. Examples of the ketones include acetone and methyl isobutyl ketone. Examples of the ethers include glyme such as propylene glycol dimethyl ether and ethylene glycol dimethyl ether. Examples of the alcohols include glycol, methanol, ethanol, isopropyl alcohol, and butanol.

  Examples of the inorganic material include silicon compounds such as silicate and siloxane. Examples of the siloxane include silsesquioxanes such as hydrogen silsesquioxane (HSQ).

  Moreover, what consists only of 1 type may be used for the said solvent, and 2 or more types may be used in combination from the point which adjusts the viscosity of a solution, a drying rate, the solubility of a structural material, etc. The structural material may be composed of only one kind, or may be used in combination of two or more kinds from the viewpoint of adjusting the viscosity of the solution, the solubility of the structural material and the hardness after drying and solidification. Also good.

  Further, the structural material is a silicon compound, the solvent is at least one selected from ethers and alcohols, and the sacrificial layer is made of an acrylic resin, an epoxy resin, and a phenol resin. It is more preferable that the combination is at least one selected from. According to the combination as described above, the contact angle θ of the sacrificial layer with respect to the solution can be realized to be less than 90 °, and a substrate having a plurality of convex portions with higher flatness and a desired shape can be easily and with high throughput. It can be manufactured with high accuracy. Moreover, as a solution in which the structural solution is dissolved in the solvent, for example, a material called spin-on-glass (SOG) can be used.

  Next, the solvent of the solution filled in the recess is dried. By doing so, the said solution with which the said recessed part was filled is solidified, and the convex part corresponding to the said recessed part is formed. The drying here may be performed as long as the shape of the formed convex portion can be maintained, and the solvent may not be completely removed. If not completely dried, the sacrificial layer may be removed and further dried. The drying method is not particularly limited, and a known drying method can be used. For example, although it may be allowed to stand at room temperature, it is preferable to further reduce the pressure, blow, and heat from the viewpoint of faster drying. Moreover, when heating, it is preferable that heating temperature does not exceed the boiling point of a solvent. By doing so, since the solution does not boil and the possibility that bubbles remain inside the formed convex portion is reduced, the occurrence of defective shape of the formed convex portion is suppressed.

  Finally, the sacrificial layer is removed so that the convex portion remains. The removal method is not particularly limited as long as only the sacrificial layer can be removed. For example, the sacrificial layer may be removed using a solvent that dissolves the sacrificial layer, for example, an organic solvent, or dry etching or oxygen. It may be removed by ashing or the like.

  By the above manufacturing method, a substrate having a plurality of fine convex portions can be easily manufactured while suppressing shape damage. Therefore, the board | substrate obtained here can be utilized suitably for the board | substrate for PM, for example.

  Further, PM can be formed by forming a magnetic layer on the surface of the substrate. That is, the apparatus includes the substrate and a magnetic layer provided on the substrate, and the magnetic layer includes a magnetic layer formed on the convex portion of the substrate and a magnetic layer formed on the substrate base material. Regularly arranged PMs are obtained. An example of the PM includes, for example, the substrate and a magnetic layer provided on the substrate, and the magnetic layer is formed on the magnetic layer formed on the convex portion of the substrate and the substrate base material. Examples thereof include PM and the like in which the formed magnetic layer is separated. If the convex portion of the substrate is made fine, PM having a high recording density can be obtained. The magnetic layer and its formation method are not particularly limited, and a known magnetic layer or a known formation method can be used. In addition, an underlayer may be provided between the substrate and the magnetic layer.

  EXAMPLES The present invention will be specifically described below with reference to examples, but the present invention is not limited to these examples.

[Example 1]
A substrate was prepared as shown in FIG.

  PAK-02 (manufactured by Toyo Gosei Co., Ltd.), which is an ultraviolet curable resin, was applied on the surface of a 2.5-inch glass substrate for hard disk drive (outer diameter 65 mm, inner diameter 20 mm) as the substrate base material 41. Then, as shown in FIG. 6A, a resin layer 42 having a plurality of columnar concave portions 43 in a square lattice shape was formed on the substrate base material 41 using the optical imprint method. Thereafter, oxygen ashing is performed on the resin layer 42 until the surface of the substrate base material 41 is exposed from the bottom surface of the recess 43. By doing so, as shown in FIG. 6B, a sacrificial layer 44 having a plurality of columnar recesses 45 with a pitch of 50 nm, a depth of 50 nm, and a diameter of 25 nm in a square lattice shape is formed on the substrate base material 41. It was.

  Next, as the solution 46, OCD T-12 900-V (manufactured by Tokyo Ohka Kogyo Co., Ltd.), which is a spin-on-glass material (SOG), was prepared. In this SOG, the solvent is propylene glycol dimethyl ether, and the solute (structural material) is ladder-type hydrogen silsesquioxane. Here, the contact angle θ of the sacrificial layer 44 with respect to the solution 46 was 30 ° and less than 90 °. In addition, d determined by L × (1-sin θ) / (2 cos θ) was 7.2 nm, which was less than 10 nm.

  And as shown in FIG.6 (c), 100 microliters of said solutions 46 were dripped on the said sacrificial layer 44 with the dispenser. Next, the substrate base material 41 provided with the sacrificial layer 44 onto which the solution 46 was dropped was spin-coated at a rotational speed of 4000 rpm for 30 seconds. By doing so, the recess 46 of the sacrificial layer 44 was filled with the solution 46. Moreover, since the solvent of the solution 46 was almost dried at the end of spin coating, drying acceleration such as heating or reduced pressure was not particularly performed. That is, as shown in FIG. 6 (d), a convex portion 47 was formed in the concave portion 45 of the sacrificial layer 44. The substrate base material 41 formed with the protrusions 47 obtained here was split and the cross section was observed with a scanning electron microscope (SEM). As a result, the structural material constituting the protrusions 47 was embedded in the recesses 45. The distance h from the bottom surface of the recess 45 to the uppermost surface of the meniscus was 20 nm and was d or more. Moreover, the amount of depressions of the meniscus was 7 nm, which almost coincided with d.

  Finally, by removing the sacrificial layer 44 by oxygen ashing, a substrate 48 in which a plurality of the protrusions 47 were formed on the substrate base material 41 was obtained as shown in FIG. When the substrate 48 obtained here was divided and the cross section thereof was observed with an SEM, the shape of the convex portion 47 was not particularly changed as compared with the above case, and the obtained substrate 48 caused a head crash. It was found to have a high level of flatness.

[Example 2]
A substrate was prepared as shown in FIG.

  ZEP520A (made by Nippon Zeon Co., Ltd., polystyrene copolymer) is applied on the surface of a 2.5-inch glass substrate (outer diameter 65 mm, inner diameter 20 mm) for hard disk drive, which is the substrate base material 51. did. Then, by electron beam drawing and development, as shown in FIG. 7A, a sacrificial layer having a plurality of cylindrical recesses 53 with a pitch of 50 nm, a depth of 50 nm, and a diameter of 25 nm on a substrate base 51 in a square lattice shape. 52 was formed.

  Next, FOx-16 (manufactured by Toray Dow Corning Co., Ltd.), which is a spin-on-glass material (SOG), was prepared as the solution 54. In this SOG, the solvent is methyl isobutyl ketone and the solute (structural material) is a cage-type hydrogen silsesquioxane. Here, the contact angle θ of the sacrificial layer 52 with respect to the solution 54 was 30 ° and less than 90 °. In addition, d determined by L × (1-sin θ) / (2 cos θ) was 7.2 nm, which was less than 10 nm.

  Then, as shown in FIG. 7B, 100 μl of the solution 54 was dropped onto the sacrificial layer 52 with a dispenser. Next, the substrate base material 51 including the sacrificial layer 52 onto which the solution 54 was dropped was spin-coated at a rotation speed of 4000 rpm for 30 seconds. By doing so, the concave portion 53 of the sacrificial layer 52 was filled with the solution 54. Moreover, since the solvent of the solution 54 was almost dried at the end of spin coating, drying acceleration such as heating or reduced pressure was not particularly performed. That is, as shown in FIG. 7C, a convex portion 55 was formed in the concave portion 53 of the sacrificial layer 52. The substrate base material 51 formed with the convex portions 55 obtained here was divided and the cross section thereof was observed with a scanning electron microscope (SEM). As a result, the structural material constituting the convex portions 55 was embedded in the concave portions 53. The distance h from the bottom surface of the recess 53 to the uppermost surface of the meniscus was 25 nm and was d or more. Moreover, the amount of depressions of the meniscus was 8 nm, which almost coincided with d.

  Finally, the sacrificial layer 52 was removed by dissolving the sacrificial layer 52 using acetone. By doing so, as shown in FIG.7 (d), the board | substrate 56 with which the said convex part 55 was formed in multiple numbers on the said board | substrate base material 51 was obtained. When the substrate 56 obtained here was divided and the cross section thereof was observed by SEM, the shape of the convex portion 55 was not particularly changed as compared with the above case, and the obtained substrate 56 caused a head crash. It was found to have a high level of flatness.

[Comparative Example 1]
A substrate was fabricated in the same manner as in Example 1 except that the height of the sacrificial layer 44 (depth of the recess 45) was 5 nm.

  Here, when the solution 46 is dropped onto the substrate base material 41 including the sacrificial layer 44 and spin-coated at a rotational speed of 4000 rpm for 30 seconds, the recess 46 of the sacrificial layer 44 is filled with the solution 46. However, the solution 46 completely covered the sacrificial layer 44. Therefore, the sacrificial layer 44 could not be removed suitably, and a substrate with high flatness could not be obtained.

  Here, the contact angle θ of the sacrificial layer 44 with respect to the solution 46 was 30 ° as in Example 1, and was less than 90 °. Further, d determined by L × (1-sin θ) / (2 cos θ) was 7.2 nm as in Example 1, and was less than 10 nm. The depth h of the recess 45 is such that the solution 46 covers all the sacrificial layer 44, so that the position of the solution 46 farthest from the substrate base 41 and the surface of the substrate base 41 It was smaller than this distance, 5 nm, and less than d.

[Comparative Example 2]
After forming the sacrificial layer 44 of the substrate base material 41, except that the release tool for coating OPTOOL DSX (manufactured by Daikin Industries, Ltd.), which is a fluorine-based release agent, is applied by a dip coating method. A substrate was produced in the same manner as in Example 1.

  Here, when the solution 46 is dropped onto the substrate base material 41 provided with the sacrificial layer 44 and spin-coated at 4000 rpm for 30 seconds, the solution 46 repels the sacrificial layer 44 and the sacrificial layer. The concave portion 45 of 44 was not filled with the solution 46. Therefore, a substrate having a desired convex portion could not be obtained.

  Here, the contact angle θ of the sacrificial layer 44 with respect to the solution 46 was 100 ° and was 90 ° or more. Moreover, d determined by L × (1-sin θ) / (2 cos θ) was −2.2 nm, which was less than 10 nm. And the depth h of the said recessed part 45 was smaller than the distance of the position farthest from the said substrate base material 41 of the said solution 46, and the surface of the said substrate base material 41, 50 nm, and was d or more.

[Comparative Example 3]
Instead of the sacrificial layer 44 having a plurality of columnar recesses 45 having a pitch of 50 nm, a depth of 50 nm, and a diameter of 25 nm in a square lattice shape, a plurality of columnar recesses 45 having a pitch of 100 nm, a depth of 50 nm, and a diameter of 50 nm are formed in a square lattice shape. A substrate was produced in the same manner as in Example 1 except that the sacrificial layer 44 was formed.

  In the substrate thus obtained, the distance h between the position farthest from the substrate base material 41 of the solution 46 and the surface of the substrate base material 41 is 20 nm, which is d or more, and the amount of depression of the meniscus Was 15 nm. Therefore, it was found that the obtained substrate 48 does not have a flatness that does not cause head crash.

  Here, the contact angle θ of the sacrificial layer 44 with respect to the solution 46 was 30 ° as in Example 1, and was less than 90 °. Moreover, d determined by L × (1-sin θ) / (2 cos θ) was 14.4 nm, which was 10 nm or more.

  From the above, (1) the contact angle θ of the sacrificial layer with respect to the solution is less than 90 °, and (2) the minimum between the side surfaces passing through the center of gravity in the cross section parallel to the surface of the substrate base material of the recess. When the distance is L, the value d determined by L × (1-sin θ) / (2 cos θ) is less than 10 nm. (3) When the solution is filled in the recess, When the distance between the position farthest from the substrate base material and the surface of the substrate base material and the length of the smaller one of the depths of the recesses satisfy all of the above d (implementation) Example 1 and Example 2) A substrate having high flatness so that the obtained substrate did not cause head crash was obtained. On the other hand, when any of the above (1) to (3) is not satisfied (Comparative Examples 1 to 3), a substrate having high flatness that does not cause a head crash cannot be obtained.

  Next, the case where the rotation speed in the spin coating method was changed was examined.

[Example 3]
A substrate was produced in the same manner as in Example 1 except that the rotation speed in the spin coating method was changed to 1000 to 7000 rpm. A substrate having high flatness that does not cause head crashes at all rotation speeds was obtained.

[Comparative Example 4]
A substrate was produced in the same manner as in Comparative Example 1 except that the rotation speed in the spin coating method was changed to 1000 to 7000 rpm. When the rotational speed was 4000 rpm or less, a substrate having high flatness that did not cause head crash could not be obtained.

  From the above, when all of the above (1) to (3) are satisfied (Example 3), high flatness that does not cause head crashes is provided regardless of the coating conditions such as the spin coating rotation speed. A substrate was obtained. On the other hand, when the above (1) is not satisfied (Comparative Example 4), depending on the coating conditions, a substrate having high flatness that does not cause a head crash cannot be obtained. This is presumably because the surface of the liquid filled in the recesses and the surface of the substrate base material are close to each other, so that it is influenced by the substrate base material.

It is a bird's-eye view which shows an example of the board | substrate base material 11 provided with the sacrificial layer 12 used for the manufacturing method of the board | substrate which concerns on this embodiment. FIG. 3 is a top view of the substrate base material 11 in a state where the recess 13 of the sacrificial layer 12 is filled with the solution as viewed from above the opening of the recess 13. It is the schematic sectional drawing which looked at the said board | substrate base material 11 shown in FIG. 2 from cut surface line III-III '. FIG. 4 is a cross-sectional view when h is d or more when the recess 13 of the sacrificial layer 12 is filled with the solution. FIG. 4 is a cross-sectional view when h is less than d when the recess 13 of the sacrificial layer 12 is filled with the solution. 1 is a drawing showing a method for manufacturing a substrate according to Example 1; 10 is a view showing a method for manufacturing a substrate according to Example 2.

Explanation of symbols

11, 41, 51 Substrate base material 12, 44, 52 Sacrificial layer 13, 43, 45, 53 Concave part 14, 46, 54 Solution 42 Resin layer 47, 55 Convex part 48, 56 Substrate

Claims (5)

A method for manufacturing a substrate having a plurality of protrusions,
The concave portion is filled with the solution by applying a solution in which the structural material constituting the convex portion is dissolved in a solvent on a substrate substrate provided with a sacrificial layer in which the concave portion corresponding to the convex portion is formed. A process of
Forming the convex portion by drying the solvent of the solution filled in the concave portion;
Removing the sacrificial layer so as to leave the convex part,
A contact angle θ of the sacrificial layer with respect to the solution is less than 90 °,
A value d determined by L × (1−sin θ) / (2 cos θ) is 10 nm, where L is a minimum distance between side surfaces passing through the center of gravity in a cross section parallel to the surface of the substrate base material. Less than,
When the recess is filled with the solution, the distance between the position of the solution farthest from the substrate base and the surface of the substrate base, and the smaller length of the depth of the recess, A method for producing a substrate, characterized by being d or more. The structural material is a silicon compound;
The solvent is at least one selected from ethers and alcohols;
The method of manufacturing a substrate according to claim 1, wherein the sacrificial layer is at least one selected from the group consisting of an acrylic resin, an epoxy resin, and a phenol resin.   The method for manufacturing a substrate according to claim 1, wherein the convex portion has a cylindrical shape.   A substrate obtained by the method for producing a substrate according to claim 1. A substrate according to claim 4 and a magnetic layer provided on the substrate,
A magnetic recording medium, wherein the magnetic layer is regularly arranged with a magnetic layer formed on a convex portion of the substrate and a magnetic layer formed on the substrate substrate.

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