JP5033615B2 - Imprint substrate - Google Patents

Description

  The present invention relates to an imprint substrate in an optical imprint method.

  Recent advances in IT technology require further development of network technology, software technology, and device technology. In particular, semiconductor integrated circuits are required to have high technologies such as high-speed operation due to miniaturization and integration, and low power consumption operation. At present, photolithographic lithography is moving from KrF laser lithography having a minimum line width of 130 nm to higher-resolution ArF laser lithography. However, the minimum line width at the mass production level of ArF laser lithography is 100 nm, whereas the manufacture of 45 nm devices is about to begin in 2007. Under such circumstances, F2 laser lithography, extreme ultraviolet exposure, electron beam reduced transfer exposure, and X-ray lithography are expected as finer technologies. However, as the miniaturization progresses, the initial cost of the exposure apparatus itself increases exponentially, and there is a problem that the price of a mask for obtaining a resolution comparable to the light wavelength used has soared. .

  On the other hand, there is an imprint technique for forming a fine pattern. This is a technology that transfers a predetermined pattern by embossing a mold having the same pattern as the pattern to be formed on the substrate against the surface of the substrate, and peeling the mold. A fine structure of 50 nm or less can be easily formed. The imprint technique has been studied for application to recording bit formation, semiconductor integrated circuit pattern formation and the like of a large capacity recording medium.

  Nanoimprint technology is roughly divided into two types depending on the material to be transferred. One is a thermal nanoimprint technique in which a material to be transferred is heated, plastically deformed by a mold, and then cooled to form a pattern. The other is photo nanoimprint, in which a liquid photo-curable resist is applied onto a substrate at room temperature, then a light-transmitting mold is pressed against the resist, and light is irradiated to cure the resist on the substrate and form a pattern. Technology. In particular, optical nanoimprint technology enables pattern formation at room temperature, so that distortion due to differences in the linear expansion coefficient between the substrate and mold due to heat is unlikely to occur, and high-precision pattern formation is possible. Have been bathed.

  When the photocurable resist is cured and then peeled off from the mold, the adhesion between the substrate and the resist is not sufficient, and the photocured resist may adhere to the mold, resulting in a defect in the concavo-convex pattern. The defect of the resist concavo-convex pattern after photocuring becomes a defect as it is when the fine concavo-convex pattern is transferred onto the substrate by dry etching or wet etching in a subsequent process.

  In order to solve such problems, Non-Patent Document 1 proposes the following transfer method. Specifically, surface treatment is performed on the substrate surface using 3-methacryloxypropyltrimethoxysilane which is a silane coupling agent. This silane coupling agent makes it possible to form a chemical bond between the substrate surface and the resist via the silane coupling agent, greatly improving the adhesion between the substrate and the resist, and performing transfer without uneven pattern defects.

Langmuir 2005, Vol21, 6127-6130

  In the method of Non-Patent Document 1, it is essential that a Si element capable of forming a siloxane coupling agent and a siloxane bond exists on the substrate. However, when other compound semiconductors or magnetic materials are present on the substrate surface, There was a problem that the reactivity with the coupling agent was low, the adhesion between the resist and the substrate was insufficient, and the resist peeled off from the substrate.

  The present invention has been made in view of the above points, and an object of the present invention is to provide an imprint substrate capable of transferring a concavo-convex pattern with a small defect rate by optical nanoimprint.

  The imprint substrate of the present invention that achieves the above-described object is a substrate used in optical nanoimprint lithography, which is formed by forming a metal compound layer on the substrate, and is applied to the optical nanoimprint lithography on the metal compound layer. It is characterized in that it forms an intermediate layer that has a greater adhesion to the photocurable resin used than the metal compound layer.

  According to the present invention, by forming the intermediate layer on the surface of the substrate on which the metal compound surface is formed, the adhesion between the substrate and the resist is improved, and transfer can be performed without causing resist peeling during pattern transfer. . Further, by applying to a magnetic recording medium or a compound semiconductor, processing accuracy can be improved.

  Next, embodiments of the present invention will be described with reference to the drawings as appropriate. FIG. 1 shows the concept of the nanoimprint process. By pressing the resist 103 disposed on the substrate 102 with the uneven shape forming portion 101 of the mold 100 and curing the resist 103, the spread resist 104 having the shape of the uneven shape forming portion 101 can be obtained. However, if the adhesion between the surface of the substrate 102 and the resist is weak as shown in FIG. 2, the resist is likely to adhere to the mold as shown in FIG. 2C (105b).

  FIG. 3 is a schematic view showing the main part of the substrate 102 according to this embodiment. A metal compound layer 107 is formed on the base substrate 106. For this reason, even if an adhesion treatment using a silane coupling agent or the like is performed in order to improve the adhesion to the resist 103, the effect is not sufficient, and film peeling tends to occur in the transfer of the fine uneven pattern. Therefore, the intermediate layer 108 having more hydroxyl groups than the metal compound layer 107 is formed on the metal compound layer 107.

  Next, the role of the intermediate layer 108 in this substrate will be described with reference to FIGS. FIG. 4 is a diagram in the case where the adhesion process is performed on the substrate 102 on which the metal compound layer 107 is formed. 4A and 4B show the case where the intermediate layer 108 is not formed, and FIGS. 4C and 4D show the case where the intermediate layer 108 is formed. When the adhesion treatment is performed on the substrate 102 on which the metal compound layer 107 is formed with a silane coupling agent, in FIG. 4A and FIG. 4B, the bonding amount of the silane coupling agent to the surface of the metal compound layer 107 is sufficient. In addition, the adhesion between the resist 103 and the substrate 102 cannot be improved. 4C and 4D, the intermediate layer 108 is formed on the surface of the metal compound layer 107. The intermediate layer 108 can form a larger number of hydroxyl groups on the surface than the surface of the metal compound layer 107. When an adhesion treatment with a silane coupling agent is performed, the intermediate layer 108 has a sufficient surface as shown in FIGS. A silane coupling agent can be bonded, and the adhesion between the resist 103 and the substrate 102 can be greatly improved.

  FIG. 5 is a diagram illustrating a state where the mold 100 and the substrate 102 on which the metal compound layer 107 is formed are peeled in the nanoimprint process. For the sake of explanation, the nanoimprint apparatus is omitted. 5A and 5B show the case where the intermediate layer 108 is not formed, and FIGS. 5C and 5D show the case where the intermediate layer 108 is formed. The resist 103 is disposed on the substrate 102 by a technique such as spin coating, dispenser, or ink jet, and the resist 103 is cured by irradiation with ultraviolet light. 5A and 5B, the adhesive force between the resist and the metal compound layer is not sufficient, and the resist adheres to the mold side at the time of peeling. This phenomenon is the same as that shown in FIG. On the other hand, since the intermediate layer 108 is formed in FIGS. 5C and 5D, the adhesion between the resist and the metal oxide layer is improved, and the resist film does not peel off when the mold and the substrate are peeled off. The mold and the substrate can be peeled off.

<Mold>
Examples of the material of the mold 100 include inorganic materials such as quartz, glass, and silicon, metals such as nickel, and various resins. Further, the outer shape of the mold 100 may be any of a circle, an ellipse, and a polygon according to the pressurization method. A center hole may be processed in the mold 100. In addition, the surface of the mold 100, particularly the surface of the concavo-convex shape forming portion 101, can be subjected to a release treatment such as fluorine or silicone in order to promote the peeling between the spread resist 104 and the mold 100. When a photoreactive substance is used as the resist 103, the mold 100 needs to be transparent with respect to the wavelength of light used for the reaction.

  The concavo-convex shape forming portion 101 on the mold 100 is formed by a known processing method according to a desired mold material and accuracy. For example, a technique such as photolithography, focused ion beam lithography, electron beam drawing method, machining such as cutting, or a replica production by a molding method from a mold master or a plating method can be employed.

<Intermediate layer>
The intermediate layer material includes at least one selected from the group consisting of Si, Ti, Al, and Sn, and further includes at least one selected from the group consisting of Ru, Pt, Pd, W, Ti, Ta, and Cr. It is desirable. Although the role of the intermediate layer is as described above, the intermediate layer may be composed of two layers including an inorganic oxide layer 108a and a mask layer 108b as shown in FIG.

  The material of the inorganic oxide layer 108a preferably includes at least one selected from the group consisting of Si, Ti, Al, and Sn. The thickness of the inorganic oxide layer is desirably 10 nm or less so as to be suitable for the etching process.

  As a material of the mask layer 108b, a material containing at least one of Ru, Pt, Pd, W, Ti, Ta, and Cr, or an oxide or nitride thereof can be used. The role of the mask layer is to prevent the inorganic oxide layer and the metal compound layer from coming into contact with each other, and the device characteristics may be affected when the inorganic oxide layer 108a comes into contact with the metal compound layer 107 at the interface. Because there is. Furthermore, as a material for the mask layer, after transferring the fine concavo-convex pattern of the mold onto the substrate by optical nanoimprint lithography, the photocurable resist pattern is etched, and when transferring the fine concavo-convex pattern onto the substrate, the substrate It is desirable that the material is made of a material that does not etch everything during the etching time in which the material is etched to a predetermined depth.

  Examples of the method for producing the intermediate layer include spin coating, dipping, or vapor deposition. The thickness of the intermediate layer should be determined in accordance with the resist etching resistance and the thickness of the base layer. If the pattern height is 100 nm or less, the thickness of the intermediate layer is 100 nm including the thickness of the base layer. The surface roughness Ra is preferably 10 nm or less.

<Board>
As the substrate, for example, a glass substrate, an Al alloy substrate, a ceramic substrate, a carbon substrate, a Si single crystal substrate, or the like can be used. Amorphous glass or crystallized glass can be used for the glass substrate. Examples of the amorphous glass include soda lime glass and aluminosilicate glass. Examples of crystallized glass include lithium-based crystallized glass. As the ceramic substrate, a sintered body mainly composed of aluminum oxide, aluminum nitride, silicon nitride or the like, or a fiber reinforced one of these sintered bodies can be used. The Si single crystal substrate, so-called silicon wafer, may have an oxide film on the surface. In addition, it is also possible to use a substrate in which a NiP layer is formed on the surface of the metal substrate or nonmetal substrate using a plating method or a sputtering method. Further, the outer shape of the substrate 102 may be any of a circle, an ellipse, and a polygon, and the center hole may be processed.

<Coupling agent>
The coupling agent described above is determined by a desired interaction with the functional group of the resist material used in each case. Thereby, for example, a π-π interaction may occur between the functional group of the silane coupling agent and the functional group of the resist material. Alternatively, a covalent reaction can be formed as a result of a chemical reaction. Another suitable interaction is a dipole interaction. Examples of the functional group that a suitable silane coupling agent has are, for example, a phenyl group, an amino group, a carboxylic acid group, an acrylate group, and a methacrylate group. Furthermore, it is desirable to form a covalent bond in order to improve the adhesion between the resist and the substrate. The coupling agent may be a polymer thereof.

Specifically, the coupling agent or the polymer thereof is a silane coupling agent represented by the following chemical formula, or a polymer that is one or more of these water-decomposable condensates or co-hydrolyzed condensates. It is preferable that Further, a titanate coupling agent or an aluminate coupling agent may be used.
[Chemical formula 1]
YnSiX (4-n)
Here, Y is an alkyl group, fluoroalkyl group, vinyl group, amino group, phenyl group, chloroalkyl group, isocyanate group, epoxy group, or an organic group containing these, and X is an alkoxyl group, acetyl group, or halogen Indicates. n is an integer from 0 to 3. The alkoxyl group represented by X is preferably a methoxy group, an ethoxy group, a propoxy group, or a butoxy group. Moreover, it is preferable that the carbon number of the whole organic group shown by Y exists in the range of 1-20, especially in the range of 5-10.

  Specific examples of the silane coupling agent include methyltrichlorosilane, methyltribromosilane, methyltrimethoxysilane, methyltriethoxysilane, methyltriisopropoxysilane, methyltrit-butoxysilane, ethyltrichlorosilane, and ethyltribromosilane. , Ethyltrimethoxysilane, ethyltriethoxysilane, ethyltriisopropoxysilane, ethyltri-t-butoxysilane, n-propyltrichlorosilane, n-propyltribromosilane, n-propyltrimethoxysilane, n-propyltriethoxysilane, n-propyltriisopropoxysilane, n-propyltri-t-butoxysilane, n-hexyltrichlorosilane, n-hexyltribromosilane, n-hexyltrimethoxysilane, n-hexyl Triethoxysilane, n-hexyltriisopropoxysilane, n-hexyltri-t-butoxysilane, n-decyltrichlorosilane, n-decyltribromosilane, n-decyltrimethoxysilane, n-decyltriethoxysilane, n-decyl Triisopropoxysilane, n-decyltri-t-butoxysilane; n-octadecyltrichlorosilane, n-octadecyltribromosilane, n-octadecyltrimethoxysilane, n-octadecyltriethoxysilane, n-octadecyltriisopropoxysilane, n- Octadecyltri-t-butoxysilane, phenyltrichlorosilane, phenyltribromosilane, phenyltrimethoxysilane, phenyltriethoxysilane, phenyltriisopropoxysilane, phenyltri-t-but Sisilane, dimethoxydiethoxysilane, dimethyldichlorosilane, dimethyldibromosilane, dimethyldimethoxysilane, dimethyldiethoxysilane, diphenyldichlorosilane, diphenyldibromosilane, diphenyldimethoxysilane, diphenyldiethoxysilane, phenylmethyldichlorosilane , Phenylmethyldibromosilane, phenylmethyldimethoxysilane, phenylmethyldiethoxysilane, trichlorohydrosilane, tribromohydrosilane, trimethoxyhydrosilane, triethoxyhydrosilane, triisopropoxyhydrosilane, tri-t-butoxyhydrosilane, vinyltrichlorosilane, vinyltri Bromosilane, vinyltrimethoxysilane, vinyltriethoxysilane, vinyltriisopropoxysilane, vinyl Nyltri-t-butoxysilane, γ-glycidoxypropylmethyldimethoxysilane, γ-glycidoxypropylmethyldiethoxysilane, γ-glycidoxypropyltrimethoxysilane, γ-glycidoxypropyltriethoxysilane, γ-glycyl Sidoxypropyltriisopropoxysilane, γ-glycidoxypropyltri-t-butoxysilane, γ-methacryloxypropylmethyldimethoxysilane, γ-methacryloxypropylmethyldiethoxysilane, γ-methacryloxypropyltrimethoxysilane , Γ-methacryloxypropyltriethoxysilane, γ-methacryloxypropyltriisopropoxysilane, γ-methacryloxypropyltri-butoxysilane, γ-aminopropylmethyldimethoxysilane, γ-aminopropyl Methyldiethoxysilane, γ-aminopropyltrimethoxysilane, γ-aminopropyltriethoxysilane, γ-aminopropyltriisopropoxysilane, γ-aminopropyltrit-butoxysilane, γ-mercaptopropylmethyldimethoxysilane, γ- Mercaptopropylmethyldiethoxysilane, γ-mercaptopropyltrimethoxysilane, γ-mercaptopropyltriethoxysilane, γ-mercaptopropyltriisopropoxysilane, γ-mercaptopropyltri-t-butoxysilane, β- (3,4-epoxy Cyclohexyl) ethyltrimethoxysilane, β- (3,4-epoxycyclohexyl) ethyltriethoxysilane, and partial hydrolysates thereof, and mixtures thereof can be used.

  The resist 103 is a target to which a fine pattern formed on the mold 100 is transferred. The resist 103 is most preferably a photocurable resin. The photocurable resin is not particularly limited, and may be a known one such as a radical polymerization system, a cationic polymerization system, or an anionic polymerization system, and a photoreactive resist added with an initiator can be used.

  Specifically, benzyl (meth) acrylate, cyclohexyl (meth) acrylate, cyclopentanyl (meth) acrylate, cyclopentenyl (meth) acrylate, adamantchel (meth) acrylate and the like are preferable. Further, ethoxylated bisphenol A di (meth) acrylate is also preferred, and those having 4 to 17 ethoxy group units in the structure are particularly preferred because of low viscosity. These (meth) acrylate materials can be applied alone or in combination with a plurality of (meth) acrylates. In addition to the above monomers, it is also possible to apply (meth) acrylate oligomers in which a plurality of these monomers are polymerized. Further, in order to promote the peeling between the mold 100 and the photocured resist 104, it is desirable to contain a fluorine compound or a silicone compound. When a photocurable resin is used for the resist 103, at least one of the mold 100 and the substrate 102 needs to be sufficiently transparent to light used for curing, and a light irradiation mechanism needs to be incorporated in the nanoimprint apparatus. . Note that a thermoplastic resin, a thermosetting resin, a high-viscosity material, or the like can be used for the resist 103. In this case, it is necessary to use a mold 100, a substrate 102, and a nanoimprint apparatus corresponding to each resist 103. .

  As a method for applying the resist 103, for example, an inkjet method, a dispensing method, a screen printing method, or the like can be used. In any method, the resist 103 is dropped on the surface of the substrate 102 or the mold 100. The dropped resist 103 is applied to the mold 100 and spreads on the surfaces of the mold 100 and the substrate 102. For the position where the resist 103 is dropped, the spread of the cured resist 104 corresponding to the concavo-convex shape forming portion 101 is evaluated in advance, and the resist 104 after curing the concavo-convex shape forming portion 101 has no gap based on this evaluation result. It is good to decide to cover.

  The substrate 102 onto which the fine pattern is transferred in the embodiment can be applied to an information recording medium such as a magnetic recording medium or an optical recording medium. Further, it can be applied to large-scale integrated circuit components, optical components such as lenses, polarizing plates, wavelength filters, light emitting elements, and optical integrated circuits, and biodevices such as immunoassay, DNA separation, and cell culture.

Example 1
In this embodiment, an example in which a tungsten silicide (WSi) film is formed as an intermediate layer is shown. As the transfer target 1, a magnetic recording medium substrate having a diameter of 65 mm, a thickness of 0.631 mm, and a center hole diameter of 20 mm was used. The substrate is made of glass, and a magnetic recording layer or the like is formed on the surface and is an opaque body. The substrate 102 has a peripheral edge and a center hole that are chamfered with a width of 0.15 mm. A tungsten silicide film having a thickness of 100 nm is formed as an intermediate layer on the substrate 102 by sputtering. The substrate 102 was immersed in a 1% methacryloxypropyltrimethoxysilane solution of the solvent toluene and heated at 50 ° C. for 1 hour. Thereafter, the substrate 102 was washed with toluene, and the adhesion treatment of the intermediate layer was performed. Resin was dropped on both surfaces of the transfer object 1 by a dispensing method. The resin was an acrylate resin to which a photosensitive substance was added, and was prepared so as to have a viscosity of 4 mPa · s. The resin was applied by a coating head in which 512 nozzles (256 × 2 rows) were arranged and the resin was discharged by a piezo method. The nozzle interval of the coating head is 70 μm in the row direction and 140 μm between the rows. Each nozzle was controlled to discharge approximately 5 pL of resin. And the resin material 103 was dripped at the surface of the board | substrate 102 with the inkjet method just before nanoimprint.

  As the mold, a quartz substrate having the same shape as the substrate 102 was used. A plurality of concentric grooves were formed on the surface of the mold facing the substrate 102 by a well-known electron beam direct writing (EB) method. This groove had a width of 50 nm, a depth of 100 nm, and a pitch of 100 nm. The central axis of the groove was made to coincide with the central axis of the mold.

FIG. 7 is a schematic diagram showing an implementation process according to the present embodiment. A silicone rubber layer having a thickness of 0.5 mm is provided on the upper surface of a stainless-made lower stage 109 that can move up and down in the nanoimprint apparatus to form a buffer layer 110. The upper stage 111 of the nanoimprint apparatus is made of a quartz plate having a thickness of 20 mm, and the mold 100 is installed with the concavo-convex shape forming portion 101 facing the lower stage 109. The substrate 102 coated with the resin material 103 is disposed on the buffer layer 110 of the lower stage 109 to raise the lower stage 109 as a reduced pressure atmosphere (about 0.01 atm) and press the substrate 102 against the mold 100 with a pressure of about 1 MPa. Then, ultraviolet rays (intensity 100 mW / cm ² ) from a high-pressure mercury lamp (not shown) were irradiated for 20 seconds. Thereafter, the lower stage 109 was lowered to release the mold 100 from the substrate 102, and a fine shape made of the resin material 104 that was spread out was formed on the substrate 102. This nanoimprint process was performed on the substrate 102. Table 1 shows the defect rate of fine shapes made of the resin material 104 on the substrate 102.

(Example 2)
In this embodiment, an SiO ₂ film is formed as an intermediate inorganic oxide layer and a Ta ₂ O ₅ film is formed as a mask layer by sputtering to a thickness of 10 nm and 100 nm, respectively. In the same manner as in Example 1, a nanoimprint process was performed on the substrate 102 on which the inorganic oxide layer and the mask layer were formed, and a fine shape made of the resin material 104 was formed on the substrate 102. Table 1 shows the defect rate of fine shapes made of the resin material 104 on the substrate 102.

(Comparative Example 1)
A substrate for a magnetic recording medium having a diameter of 65 mm, a thickness of 0.631 mm, and a center hole diameter of 20 mm is used as the transfer target 1. The substrate is made of glass, and a magnetic recording layer or the like is formed on the surface and is an opaque body. A nanoimprint process was performed on the substrate 102 on which the inorganic oxide layer and the mask layer were formed in the same manner as in Example 1 except that the intermediate layer was not formed, and a fine shape made of the resin material 104 was formed on the substrate 102. . Table 1 shows the defect rate of fine shapes made of the resin material 104 on the substrate 102.

(Comparative Example 2)
An example in which a substrate for magnetic recording medium having a diameter of 65 mm, a thickness of 0.631 mm, and a center hole diameter of 20 mm is used as the transfer target 1, and a Ta ₂ O ₅ film is formed as a mask layer to a thickness of 100 nm by sputtering. . The substrate is made of glass, and a magnetic recording layer or the like is formed on the surface and is an opaque body. Except not forming an inorganic oxide layer, it carried out similarly to Example 2, and the nanoimprint process was implemented about the board | substrate 102 with which the mask layer was formed, and the fine shape which consists of the resin material 104 was formed on the board | substrate 102. FIG. Table 1 shows the defect rate of fine shapes made of the resin material 104 on the substrate 102.

(Example 3)
In this embodiment, a method for manufacturing a discrete track medium using the imprint substrate of the present invention will be described with reference to the drawings as appropriate. In the drawings to be referred to, FIG. 8 is a schematic diagram showing a recording medium according to the present embodiment. In this figure, a schematic diagram of a so-called discrete track medium (DTM) in which each recording track is magnetically separated is shown, but the present embodiment is also applied to a bit patterned medium (BPM) in which each recording bit is separated. The process shown in the example is applicable.

  The magnetic recording medium 200 has a disk shape with a diameter of 65 mm and a thickness of 0.631 mm, and has a structure in which a plurality of magnetic layers and other layers are deposited on a substrate 201. A hole 202 having a diameter of 20 mm for fixing the magnetic recording medium 200 to the spindle is provided at the center of the substrate 201.

  The recording track 203 is formed concentrically, and has a structure in which it is magnetically separated from adjacent tracks by a nonmagnetic material. The outermost surface of the magnetic recording medium 200 is flattened, and the difference in height between the recording track 203 and the non-magnetic region is less than 5 nm. The center-to-center distance between adjacent recording tracks 203, that is, the track pitch (Tp) needs to be determined according to the recording density. In this embodiment, Tp is 150 nm at the center. Tp is changed depending on the radius value of the disk on the magnetic recording medium 200. This is to cope with a yaw angle caused by driving a recording / reproducing head by a rotary actuator in a hard disk drive (HDD). When the recording / reproducing head is driven using a linear actuator, a constant Tp may be adopted regardless of the radius value.

  The magnetic recording medium 200 is also provided with a servo pattern 204 for accessing a region on a desired track and performing a recording / reproducing operation. In FIG. 8, the servo pattern 204 is schematically shown as a curve, but a fine pattern exists inside. This pattern structure will be described later. Further, in the present embodiment, one round is divided into 200 so that the servo pattern 204 enters each area. Of course, the number of servo patterns is not limited to 200 and needs to be determined from the recording / reproducing characteristics.

  Further, the magnetic recording medium 200 can be provided with an inner peripheral portion 205 and an outer peripheral portion 206 in which the recording track 203 and the servo pattern 204 are not formed.

  The manufacturing process of this medium will be described with reference to FIG. In the manufacturing process, a soft magnetic backing layer 207 (SUL) was first grown on the substrate 201. The material of the substrate 201 is not limited to glass, and a metal such as aluminum, a semiconductor such as silicon, an insulator such as ceramics or polycarbonate, and the like can be selected. The soft magnetic backing layer 207 employs an Fe—Ta—C alloy and is subjected to necessary heat treatment after sputter deposition in a vacuum chamber. The soft magnetic backing layer 207 is preferably provided with magnetic anisotropy in the medium radial direction. Instead of the Fe—Ta—C alloy, another soft magnetic backing layer 207 may be used, and other growth methods other than sputtering deposition may be employed. Further, if necessary, an adhesion layer for improving the adhesion between the substrate 201 and the soft magnetic backing layer 207, an intermediate layer for controlling the crystallinity of the soft magnetic backing layer 207, or the like may be inserted. After the formation of the soft magnetic backing layer 207, the recording layer 208 is subsequently grown by sputtering deposition in a vacuum. In this embodiment, a Co—Cr—Pt film is used as the recording layer 208. This material is characterized by having an easy axis of magnetization in a direction perpendicular to the film surface direction. Therefore, in this embodiment, the sputter deposition conditions are selected so that the axis of magnetic anisotropy is substantially perpendicular to the substrate surface. The magnetic material used for the recording layer 208 is not limited to the Co—Cr—Pt alloy, and other materials may be used. Further, as described in Example 1, the intermediate layer 209 was formed. The substrate 201 shown in FIG. 9A is formed by the above process.

  Subsequently, the nanoimprint process shown in FIGS. 8B, 8C, and 8D is performed. In this figure, the nanoimprint apparatus is omitted for simplification. Hereinafter, the process up to the end of photocuring is performed under ultraviolet cut. An acrylate photocurable resin (hereinafter referred to as a resist 210) to which a liquid photosensitive material is added is applied on the flat structure completed by the above process. In this embodiment, the resist 210 is applied using the ink jet method described in the first embodiment.

  The substrate 201 thus coated with the resist 210 is placed on the lower stage on the nanoimprint apparatus with the resist coating surface facing upward as shown in FIG. 9B. The mold 211 having a diameter of 65 mm and a thickness of 1 mm is arranged on the upper stage of the nanoimprint apparatus so that the resist coating surface of the substrate 201 and the unevenness forming surface of the mold 211 face each other. In this embodiment, the mold 211 is made of quartz, but other materials may be used as long as they can transmit light having a wavelength necessary for curing the resist 210. In this embodiment, the mold 211 is also formed with a central hole 202 having a diameter of 20 mm, which is the same as that of the substrate. This center hole 202 was used to mechanically align the center position with respect to the mold 211 and the substrate 201. Although not used in this embodiment, a feedback mechanism based on optical measurement may be used as necessary. The moving mechanism used for alignment can move in a horizontal plane, move up and down, rotate, and tilt. The mold 211 is formed with a concave and convex shape corresponding to the recording track 203 and the servo pattern 204 formed on the magnetic recording medium 200 and having a mirror-like relationship. The depths of the recesses formed in the mold 211 are all 100 nm.

After the positioning, as shown in FIG. 9C, the mold 211 and the substrate 201 were contacted with a pressure of 0.9 MPa and then irradiated with light. In this embodiment, a 100 mW / cm ² high-pressure mercury lamp was used as the light source. Although the irradiation amount depends on the type of the resist 210, it is set to 0.3 mJ / cm ^{2 in} this embodiment. This value needs to be changed according to the type of resist 210 used, irradiation conditions, and the like. The light intensity was measured in advance and controlled by the irradiation time so as to reach the required energy. Of course, a photodetector may be installed in the chamber, and the amount of light may be measured by monitoring the amount of light in real time. After photocuring, as shown in FIG. 9D, the substrate 201 and the mold 211 were vacuum-sucked from the back surface, and peeling was performed by applying a tensile stress in a direction perpendicular to the surface of the substrate 201. A resist 212 cured by this step was formed on the substrate 201.

  Next, the disk was taken out from the nanoimprint apparatus and milled with ions from above with an ion milling apparatus. In this embodiment, Ar is used as the ionic species, but other ionic species may be used. Alternatively, pattern transfer may be performed by reactive ion etching (RIE) or wet etching instead of ion milling. Through this step, the entire cured resist 212 is thinned, and the intermediate layer 209 and the recording layer 208 under the thin region of the cured resist 212 are removed by exposure to argon ions. Through this step, the uneven shape of the cured resist 212 is formed on the recording layer 208 as shown in FIG. Although not performed in this step, the resist 212 previously cured with oxygen plasma is etched before ion milling, and the thin region of the cured resist 212 is removed so that the underlying magnetic film 208 is directly behind. In the ion milling step, exposure to argon ions is more preferable in terms of improving pattern accuracy.

  Thereafter, the hardened resist 212 is removed by a rinsing step, and the recording layer 208 having the uneven shape shown in FIG. 9F can be formed. Thereafter, if necessary, the nonmagnetic material 213 is embedded in the groove. For example, Si—O can be grown from the top of the substrate and planarized by etch back or chemical mechanical polishing (CMP). Further, if necessary, a protective film 214 and a lubricating film (not shown) are further grown to complete the magnetic recording medium 200 shown in FIG. In this embodiment, by forming the intermediate layer 209 on the recording layer 208, the pattern defect rate can be reduced, so that highly accurate processing can be performed.

The conceptual diagram of a nanoimprint process. The conceptual diagram of the nanoimprint process when a photocurable resist peels from the board | substrate. FIG. The schematic diagram which shows the effect of the intermediate | middle layer in this invention. The schematic diagram which shows the effect at the time of applying the intermediate | middle layer in this invention to nanoimprint. The block diagram of the intermediate | middle layer in this invention. FIG. 3 is a schematic diagram showing a transfer process of Example 1. FIG. 6 is a schematic diagram illustrating a recording medium of Example 3. FIG. 6 is a schematic diagram showing a manufacturing process of a recording medium of Example 3.

Explanation of symbols

100, 211 Mold 101 Concavity and convexity forming portions 102 and 201 Substrate 103 Photocurable resist 104 Photocurable resist 105a spread and spread by mold Photocurable resist 105b having concave and convex shape transferred onto the substrate Light attached to the mold Curable resist 106 Underlying substrate 107 Metal compound layer 108 Intermediate layer 108a Inorganic oxide layer 108b Mask layer 109 Lower stage 110 Buffer layer 111 Upper stage 200 Magnetic recording medium 202 Hole 203 Recording track 204 Servo pattern 205 Outer peripheral part 206 Inner peripheral part 207 Soft magnetic backing layer 208 Recording layer 209 Intermediate layer forming part 210 Resist 212 Hardened resist 213 Nonmagnetic material 214 Protective film

Claims (2)

A substrate used in optical nanoimprint lithography,
And a metal compound layer having a magnetic layer formed on a substrate,
An intermediate layer formed on the surface of the metal compound layer ,
The intermediate layer is composed of two or more layers of an outermost inorganic oxide layer and a mask layer formed between the metal compound layer and the inorganic oxide layer,
The inorganic oxide layer is made of a material including at least one selected from the group consisting of Si, Ti, Al, and Sn;
The mask layer is made of a material containing at least one of a metal group consisting of Ru, Pt, Pd, W, Ti, Ta, Cr,
The imprint substrate, wherein the inorganic oxide layer is surface-treated with a coupling agent . The imprint substrate according to claim 1, wherein the inorganic oxide layer has a thickness of 10 nm or less.

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