JP2010250940A - Imprinting apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an imprinting apparatus that easily separates a stamper pressed to a resist on the surface of a medium substrate after imprinting. <P>SOLUTION: The imprinting apparatus includes: a first die for holding a disc-shaped stamper having a concavo-convex pattern formed thereon; a second die for holding a disc-shaped substrate with a resist applied thereon to face the stamper held by the first die; and a suction ring that is arranged around the first die and has an outer groove for sucking in a vacuum the circumference of the stamper held by the first die and an inner groove for opening the circumference of the stamper to air. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to an imprint apparatus used when a pattern is transferred to a resist by an imprint method.

  As a magnetic recording medium capable of improving the recording density, a discrete track type magnetic recording medium has been proposed. In the discrete track type magnetic recording medium, a magnetic recording layer between recording tracks is removed or modified to form a non-recording portion, and interference between adjacent recording tracks is suppressed.

  Discrete track type magnetic recording media are manufactured using an imprint method in consideration of production efficiency. A method of manufacturing a discrete track magnetic recording medium using the imprint method will be schematically described.

  A resist is applied on the master substrate, and a resist master having a concavo-convex pattern formed by electron beam lithography is produced. A conductive film is formed on the resist master, a Ni electroformed film is deposited by electroforming, and the Ni electroformed film is peeled off from the resist master to produce a Ni stamper. On the other hand, a magnetic recording layer is formed on the medium substrate, and a resist is applied on the magnetic recording layer. Next, an imprint apparatus having first and second molds is prepared, a stamper is held in the first mold, a medium substrate is held in the second mold, and the stamper and the medium substrate are mutually connected. Make them face each other. In this state, the stamper is pressed against the resist on the surface of the medium substrate to transfer the uneven pattern of the stamper to the resist, and then the stamper is peeled off. Thereafter, the magnetic recording layer is etched using the resist having the concavo-convex pattern transferred thereon as a mask to form a magnetic pattern such as a discrete track.

  As an imprint apparatus, for example, an apparatus described in Patent Document 1 is known. In this apparatus, gas is supplied to the lower surface of the medium substrate, and imprinting is performed from the central portion of the medium substrate toward the peripheral portion.

  However, in the conventional imprint apparatus, it is difficult to remove the stamper pressed against the resist on the surface of the medium substrate after imprinting.

  FIG. 1 schematically shows a perspective view of a stamper. As shown in FIG. 1, when the stamper 1 is viewed from the upper surface (pattern surface), it is warped so that the central portion is low and the peripheral portion is high. The height of the warp measured from the plane indicated by the broken line is, for example, a maximum value Hmax of 1.0 mm, a minimum value Hmin of 0.5 mm, and an average value of 0.75 mm.

  With reference to the cross-sectional views shown in FIGS. 7A to 7C, problems that occur when using an example of a conventional imprint apparatus will be described. As shown in FIG. 7A, the stamper 1 having warpage is placed on the lower mold 11, and these center holes are inserted into the pins 12. On the other hand, the medium substrate 2 coated with the resist 3 is held on the upper mold 13, and these center holes are inserted into the pins 12. As shown in FIG. 7B, the lower mold 11 and the upper mold 13 are uniformly pressed to transfer the pattern of the stamper 1 to the resist 3 on the medium substrate 2. As shown in FIG. 7C, the stamper 1 is peeled off from the resist 3 on the surface of the medium substrate 2 by using the restoring force of the stamper 1 that raises the upper mold 13 and returns to the warped state. However, if only the restoring force of the stamper 1 is used, a part of the stamper 1 may not be peeled off from the resist 3. When an external force is applied to an unpeeled portion and the film is forcibly separated, a transfer defect occurs at that portion. Since this transfer defect is displayed in white in an OSA (Optical surface analyzer) inspection image, it is called a “white unevenness” defect.

  8A and 8B show another conventional imprint apparatus. FIG. 8A is an exploded perspective view in which the imprint apparatus, a stamper held by the imprint apparatus, and the medium substrate are partially broken. FIG. 8B is a perspective view illustrating a state in which the stamper and the medium substrate are held in the imprint apparatus, partially broken. The center hole of the lower mold 11 is inserted into the pin 12. A suction ring 14 is disposed around the lower mold 11. A groove 15 is formed between the upper outer peripheral surface of the lower mold 11 and the upper inner peripheral surface of the suction ring 14. The groove 15 communicates with the suction path 16 through a communication hole (not shown) provided in a part of the bottom surface in the groove 15. The suction path 16 is connected to a vacuum pump (not shown). The center hole of the stamper 1 is inserted into the pin 12. On the other hand, the adhesive sheet 4 is attached to the lower surface of the upper mold 13, and the medium substrate 2 is adhered to the adhesive sheet 4.

  With reference to the cross-sectional views shown in FIGS. 9A to 9D, problems that occur when another conventional imprint apparatus is used will be described. As shown in FIG. 9A, the stamper 1 having warpage is placed on the lower mold 11, and these center holes are inserted into the pins 12. On the other hand, the adhesive sheet 4 is attached to the lower surface of the upper mold 13, the medium substrate 2 is adhered and held on the adhesive sheet 4, and these center holes are inserted into the pins 12. As shown in FIG. 9B, the lower surface of the stamper 1 is attracted to the upper surfaces of the lower mold 11 and the suction ring 14 by evacuating the groove 15. At this time, since the gap between the lower surface of the stamper 1 and the upper surfaces of the lower mold 11 and the suction ring 14 is entirely reduced, the stamper 1 is in a state close to a plane. As shown in FIG. 9C, the lower mold 11 and the upper mold 13 are uniformly pressed to transfer the pattern of the stamper 1 to the resist 3 on the medium substrate 2. As shown in FIG. 9D, the upper mold 13 is raised. However, when the stamper 1 is in a state close to a flat surface, a large external force is required for peeling, and it is difficult to peel the stamper 1 from the resist 3 on the surface of the medium substrate 2. In some cases, separation may occur between the medium substrate 2 and the adhesive sheet 4.

JP 2007-305895 A

  An object of the present invention is to provide an imprint apparatus that can easily peel off a stamper pressed against a resist on the surface of a medium substrate after imprinting.

  According to one embodiment of the present invention, a first mold for holding a disk-shaped stamper on which a concavo-convex pattern is formed and a disk-shaped substrate to which a resist is applied are held by the first mold. A second mold held opposite to the stamper, and an outer periphery disposed around the first mold for vacuum suction of the outer periphery of the stamper held by the first mold. There is provided an imprint apparatus comprising a suction ring formed with a side groove and an inner groove for opening the outer periphery of the stamper to the atmosphere.

  Since the imprint apparatus of the present invention has an adsorption ring in which an inner groove that is open to the atmosphere and an outer groove that is vacuum-sucked are formed, the stamper pressed against the resist on the surface of the medium substrate can be easily peeled off after imprinting. Can do.

The perspective view which shows a stamper. FIG. 2 is an exploded perspective view showing the imprint apparatus according to the embodiment of the present invention with a part thereof broken. Sectional drawing which shows the imprint method using the imprint apparatus which concerns on embodiment of this invention. The figure which shows the result of having simulated the shape of the stamper in this invention and the conventional imprint method. Sectional drawing which shows the manufacturing method of a discrete track | truck type | mold magnetic recording medium. 1 is a block diagram of a magnetic recording apparatus incorporating a discrete track type magnetic recording medium. Sectional drawing which shows the imprint method using the imprint apparatus which concerns on an example of the past. FIG. 12 is an exploded perspective view showing a partially broken imprint apparatus according to another conventional example. Sectional drawing which shows the imprint method using the imprint apparatus which concerns on the other conventional example.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 2 shows an imprint apparatus according to an embodiment of the present invention. FIG. 2 is an exploded perspective view showing the imprint apparatus, a stamper held by the imprint apparatus, and a medium substrate, partially cut away. The center hole of the lower mold 11 is inserted into the pin 12. A suction ring 21 is disposed around the lower mold 11. An inner groove 22 is formed between the upper outer peripheral surface of the lower mold 11 and the upper inner peripheral surface of the suction ring 21. The inner groove 22 communicates with the atmosphere release path 23 through a communication hole (not shown) provided in a part of the bottom surface in the inner groove 22. An outer groove 24 is formed on the upper surface of the lower mold 11 at a position outside the inner groove 22. The outer groove 24 communicates with the suction path 25 through a communication hole provided in a part of the bottom surface in the outer groove 24. The suction path 25 is connected to a vacuum pump (not shown). As shown in FIG. 1, the center hole of the stamper 1 that has warped is inserted into the pin 12, and the stamper 1 is placed on the lower mold 11 and the suction ring 21. On the other hand, a groove 26 is formed on the inner peripheral side lower surface of the upper mold 13, and this groove 26 communicates with a plurality of communication holes 27 penetrating the upper mold 13 vertically. The plurality of communication holes 27 are connected to a vacuum pump (not shown). The medium substrate 2 is held on the lower surface of the upper mold 13.

  In addition, it is preferable that the width | variety of the inner side groove | channel 22 is 0.1-2 mm, the width | variety of the outer side groove | channel 24 is 0.1-3 mm, and the space | interval between both grooves is 0.5-2 mm. The dimensions of the lower mold 11, the pins 12, and the upper mold 13 are appropriately designed according to the size of the medium substrate 2.

  With reference to the cross-sectional views shown in FIGS. 3A to 3D, an imprint method using the imprint apparatus according to the embodiment of the present invention will be described. As shown in FIG. 3A, the stamper 1 having warpage is placed on the lower mold 11, and these center holes are inserted into the pins 12. On the other hand, the inner peripheral portion of the back surface of the medium substrate 2 is vacuum-sucked and held by the groove 26 on the lower surface of the upper mold 13, and these center holes are inserted into the pins 12. As shown in FIG. 3B, the outer peripheral groove 15 is evacuated to adsorb the lower surface peripheral portion of the stamper 1 to the upper surface of the adsorption ring 21. Since the inside of the inner groove 22 is open to the atmosphere, the upper surface and the lower surface of the stamper 1 are at atmospheric pressure, and the inner peripheral portion of the stamper 1 is not adsorbed by the lower mold 11. At this time, the stamper 1 warps contrary to FIG. 3A, and the inner peripheral side is higher and the outer peripheral side is lower. As shown in FIG. 3C, the lower mold 11 and the upper mold 13 are uniformly pressed to transfer the pattern of the stamper 1 to the resist 3 on the medium substrate 2. As shown in FIG. 3D, when the upper mold 13 is raised, the stamper 1 tries to return to the state shown in FIG. For this reason, the separation of the stamper 1 from the resist 3 on the surface of the medium substrate 2 starts from the outer peripheral side and proceeds concentrically toward the inner peripheral side. In this case, the last separation occurs on the innermost periphery of the medium substrate 2. Since the innermost circumference of the medium substrate 2 is not used as a data area, no problem occurs even if a transfer failure occurs in this portion.

  FIGS. 4 (a) and 4 (b) show the simulation results of the stamper shape in the present invention and the conventional imprint method, respectively. The horizontal axis of each figure is a radius coordinate, and the position of the radius coordinate 0 mm is the center of the center hole. The vertical axis of each figure is the stamper bottom surface height.

  FIG. 4A shows the state of FIG. 3B in the imprint apparatus according to the present invention, in which the inner peripheral side of the stamper is warped by about 0.15 mm. As shown in FIG. 3D, when the upper die is raised after imprinting, a restoring force is exerted to return the stamper to the state where the inner peripheral side of the stamper is warped. Therefore, the stamper 1 is improved from the resist 3 on the surface of the medium substrate 2. Peel off.

  FIG. 4B is the state of FIG. 9B in the conventional imprint apparatus, and the stamper is substantially flat. For this reason, when the upper mold is raised after imprinting as shown in FIG. 9D, the resist 3 on the surface of the medium substrate 2 and the stamper 1 are brought into close contact with each other, and peeling becomes difficult.

  In FIG. 2, the groove 26 and the communication hole 27 are provided in the upper mold 13 so that the medium substrate 2 is vacuum-sucked. However, an adhesive sheet is attached to the upper mold 13 and the medium substrate 2 is attached to the adhesive sheet. It may be adhered.

  3A to 3D, the case where the inner groove 22 is always opened to the atmosphere has been described. On the other hand, not only the outer groove 23 but also the inner groove 22 is vacuumed at the time of imprinting in FIG. 3B, so that the stamper 1 is flattened, and the inner groove 22 is released to the atmosphere at the time of peeling in FIG. The stamper 1 may be peeled off from the resist 3 on the surface of the medium substrate 2 by raising the mold 12.

  In order to adopt such a method, in the apparatus shown in FIG. 2, the inner groove 22 is opened to the atmosphere through a three-way valve or vacuumed, and the outer groove 24 is vacuumed. Good.

  As shown in FIG. 1, when the stamper 1 that has been warped unevenly is held only by the pressurization between the lower mold 11 and the upper mold 13, a secondary component of RRO (repeatable runout) is generated. Sometimes. On the other hand, if the stamper 1 is made flat by vacuum suction of the inner groove 22 in the step of FIG. 3B, RRO can be reduced.

  Next, a method for manufacturing a magnetic recording medium using the imprint method according to the present invention will be described with reference to FIGS.

  As shown in FIG. 5A, a soft magnetic underlayer 52 and a magnetic recording layer 53 are formed on a substrate 51, and a resist 60 is applied thereon.

  Examples of the substrate 51 include a glass substrate, an Al-based alloy substrate, a ceramic substrate, a carbon substrate, a Si single crystal substrate having an oxide surface, and those substrates plated with NiP or the like.

  As the soft magnetic underlayer 52, a material containing Fe, Ni, or Co is used. More specifically, FeCo alloys such as FeCo and FeCoV, FeNi alloys such as FeNi, FeNiMo, FeNiCr and FeNiSi, FeAl alloys and FeSi alloys such as FeAl, FeAlSi, FeAlSiCr, FeAlSiTiRu, FeAlO and the like, FeTa alloys Examples thereof include FeTa, FeTaC, and FeTaN, and FeZr alloys such as FeZrN.

  As the magnetic recording layer 53, for example, a magnetic material containing Co as a main component, containing at least Pt, further containing an oxide, and having perpendicular magnetic anisotropy is used. As the oxide, silicon oxide and titanium oxide are particularly preferable.

  The resist 60 is used as a mask material for performing uneven processing of the magnetic recording layer 53 after transferring the uneven pattern by imprint described later. As the resist material, a material that can be transferred by imprinting after imprinting is used, and examples thereof include polymer materials, low-molecular organic materials, and liquid Si resists such as spin-on-glass (SOG).

  In FIG. 5B, the concavo-convex pattern is transferred by imprinting. A stamper (not shown) in which a desired uneven pattern is formed on the entire surface of the resist 60 is evenly pressed to transfer the uneven pattern to the surface of the resist 60. The concave portion of the resist 60 formed by this transfer process corresponds to the concave portion formed in the magnetic recording layer 53.

  In FIG. 5C, the magnetic recording layer 53 is processed. The resist residue remaining in the recesses of the resist 60 having the concavo-convex pattern obtained in FIG. 5B is removed, and the magnetic recording layer 53 is exposed. Next, a concave portion is formed in the magnetic recording layer 53 by ion milling using the remaining patterned resist 60 as a mask.

  In FIG. 5D, the remaining resist is removed by etching.

In FIG. 5E, the buried layer 54 having a sufficient thickness is formed by sputtering. As the buried layer 54, a nonmagnetic material is used, and examples thereof include carbon (C), oxides such as SiO ₂ and Al ₂ O _3, and metals such as Ti.

  In FIG. 5F, the buried layer 54 is etched back until the magnetic recording layer 53 is reached, and the buried layer 54 is buried in the recess, thereby flattening the surface.

Thereafter, a protective layer is formed on the surface. The protective layer has the purpose of preventing corrosion of the perpendicular recording layer and preventing damage to the medium surface when the magnetic head comes into contact. Examples of the protective layer include materials containing carbon (C), SiO ₂ , and ZrO ₂ . Further, a lubricant is applied to the surface.

  Next, a magnetic recording apparatus equipped with the magnetic recording medium manufactured as described above will be described. FIG. 6 shows a block diagram of the magnetic recording apparatus. In this figure, the head slider is shown only on the upper surface of the magnetic recording medium. However, perpendicular magnetic recording layers having discrete tracks are formed on both sides of the magnetic recording medium, and the down head / up is formed on the upper and lower surfaces of the magnetic recording medium. Each head is provided.

  The disk drive includes a main body called a head disk assembly (HDA) 100 and a printed circuit board (PCB) 200.

  A head / disk assembly (HDA) 100 includes a magnetic recording medium (DTR medium) 70, a spindle motor 101 that rotates the magnetic recording medium 70, an actuator arm 103 that rotates about a pivot 102, and a tip of the actuator arm 103. A suspension 104 mounted on the head, a head slider 105 supported by the suspension 104 and including a read head and a write head, a voice coil motor (VCM) 106 that drives the actuator arm 103, and a head amplifier that amplifies the input / output signals of the head. (Not shown). A head amplifier (HIC) is provided on the actuator arm 103 and connected to a printed circuit board (PCB) 200 through a flexible cable (FPC) 120. If the head amplifier (HIC) is provided on the actuator arm 103 as described above, the noise of the head signal can be effectively reduced, but the head amplifier (HIC) may be fixed to the HDA body.

  As described above, the magnetic recording medium 70 has the perpendicular magnetic recording layers formed on both surfaces, and the servo areas are formed on each of the both surfaces so as to coincide with the trajectory of the head movement. The specifications of the magnetic recording medium satisfy the outer diameter and inner diameter suitable for the drive, recording / reproducing characteristics, and the like. The radius of the arc formed by the servo area is given as the distance from the pivot to the magnetic head element.

  The printed circuit board (PCB) 200 is equipped with four main system LSIs. These are a disk controller (HDC) 210, a read / write channel IC 220, an MPU 230, and a motor driver IC 240.

  The MPU 230 is a control unit of the drive drive system, and includes a ROM, a RAM, a CPU, and a logic processing unit that realize the head positioning control system according to the present embodiment. The logic processing unit is an arithmetic processing unit configured by a hardware circuit, and performs high-speed arithmetic processing. The operation software (FW) is stored in the ROM, and the MPU controls the drive according to the FW.

  A disk controller (HDC) 210 is an interface unit in the hard disk, and exchanges information between the disk drive and a host system (for example, a personal computer), an MPU, a read / write channel IC, and a motor driver IC. Manage.

  The read / write channel IC 220 is a head signal processing unit related to read / write, and includes a circuit for processing recording / reproduction signals such as head amplifier (HIC) channel switching and read / write.

  The motor driver IC 240 is a drive driver unit for the voice coil motor (VCM) 106 and the spindle motor 101. The motor driver IC 240 controls driving of the spindle motor 101 at a constant rotation, or supplies the VCM operation amount from the MPU 230 to the VCM 106 as a current value. Drive the moving mechanism.

  DESCRIPTION OF SYMBOLS 1 ... Stamper, 2 ... Medium substrate, 3 ... Resist, 11 ... Lower metal mold, 12 ... Pin, 13 ... Upper metal mold, 21 ... Adsorption ring, 22 ... Inner groove, 23 ... Air release path, 24 ... Outer groove, 25 ... Suction path, 26 ... Groove, 27 ... Communication hole, 51 ... Substrate, 52 ... Soft magnetic underlayer, 53 ... Magnetic recording layer, 54 ... Embedded layer, 55 ... Protective layer, 60 ... Resist, 70 ... DTR medium DESCRIPTION OF SYMBOLS 100 ... Head disk assembly (HDA) 101 ... Spindle motor 102 ... Pivot 103 ... Actuator arm 104 ... Suspension 105 ... Head slider 106 ... Voice coil motor (VCM) 120 ... Flexible cable (FPC) , 200 ... printed circuit board (PCB), 210 ... disk controller (HDC), 220 ... read / write channel IC, 230 ... PU, 240 ... motor driver IC.

Claims (7)

A first mold for holding a disc-shaped stamper on which an uneven pattern is formed;
A second mold for holding a disk-shaped substrate coated with a resist so as to face the stamper held by the first mold;
An outer groove disposed around the first mold and vacuum-sucked at the outer periphery of the stamper held by the first mold; and an inner groove for releasing the outer periphery of the stamper to the atmosphere. An imprinting apparatus comprising: a suction ring formed with an ink.   The imprint apparatus according to claim 1, wherein the first mold and the suction ring are integrated.   The imprint apparatus according to claim 1, wherein the second mold is provided with a groove for vacuum suction of the substrate.   The imprint apparatus according to claim 3, wherein the groove of the second mold is provided so as to vacuum-suck the inner peripheral portion of the substrate. A first mold for holding a disc-shaped stamper on which an uneven pattern is formed;
A second mold for holding a disk-shaped substrate coated with a resist so as to face the stamper held by the first mold;
An outer groove that is disposed around the first mold and vacuum-sucks the outer periphery of the stamper held by the first mold and the outer periphery of the stamper is opened to the atmosphere via a three-way valve; or An imprinting apparatus comprising an adsorption ring having an inner groove for vacuum suction.   The outer periphery of the stamper is vacuumed through the inner and outer grooves during imprinting, the outer periphery of the stamper is released to the atmosphere through the inner groove during peeling, and the outer periphery of the stamper is vacuumed through the outer groove. The imprint apparatus according to claim 5. Using the imprint apparatus according to any one of claims 1 to 6,
Placing the suction ring around the first mold, and placing a disk-shaped stamper having a concavo-convex pattern formed on the first mold and the suction ring;
The outer peripheral portion of the stamper is evacuated through the outer groove, and the outer peripheral portion of the stamper is released to the atmosphere or evacuated through the inner groove, thereby adsorbing the lower peripheral edge of the stamper on the upper surface of the suction ring. ,
Holding a disk-shaped substrate coated with a resist on the lower surface of the second mold, facing the stamper held in the first mold;
Pressurizing the first mold and the second mold to transfer the stamper pattern to a resist on the substrate;
An imprinting method, wherein the stamper is peeled off from the resist on the surface of the substrate by moving the second mold upward and progressing from the outer peripheral side toward the inner peripheral side.

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