JP2007109293A - Resin layer forming apparatus, resin layer forming method and manufacturing method of optical disk - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a resin layer forming apparatus and a resin layer forming method capable of suppressing a protrusion generated at an outermost peripheral part and forming a resin layer having a uniform thickness, and to provide a manufacturing method of an optical disk. <P>SOLUTION: The resin layer forming apparatus is constituted of a spinner table 21, a center pin 22, a uniaxial robot 23 and a spot UV head 24 installed on the uniaxial robot 23. The spot UV head 24 is installed at the tip of the uniaxial robot 23 and has such a structure that a substrate 31 can be irradiated with spot UV from an inner peripheral part to an outer peripheral part so that the vicinity of the outermost peripheral part of the substrate 31 is not irradiated with UV. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  TECHNICAL FIELD The present invention relates to a resin layer forming apparatus, a resin layer forming method, and an optical disc manufacturing method. For example, resin layer formation for forming resin layers such as a cover layer, an intermediate layer, and a lubricant layer in a high-density recording optical disc to a uniform thickness The present invention relates to an apparatus, a resin layer forming method, and an optical disc manufacturing method.

  High-density recording of an optical disk can be realized, for example, by shortening the wavelength of laser light used in an optical pickup, increasing the numerical aperture NA (Numerical Aperture) of the objective lens, and reducing the size of the focused spot.

  For example, a CD (Compact Disc) has a laser beam wavelength of 780 nm, a numerical aperture NA of 0.45, and a recording capacity of 650 MB (megabytes). A DVD-ROM (Digital Versatile Disc-ROM) has a laser beam wavelength of 650 nm and a numerical aperture of 0.6, and has a recording capacity of 4.7 GB (gigabytes).

  Further, in the next generation high-density recording optical disc, the wavelength of the laser beam is 450 nm or less, and the NA is 0.78 or more, which makes it possible to increase the capacity of 22 GB or more with a single layer. In a high-density recording optical disk, a light-transmitting protective film called a cover layer is formed on the signal reading surface side of the disk. The cover layer has a thickness of, for example, 100 μm (0.1 mm).

  In CD and DVD, the distance from the signal reading surface (disc surface) of the disc to the information recording layer where the signal is recorded is relatively large. In the case of CD, this distance is about 1 mm. In the case of DVD, This distance is about 0.6 mm.

  On the other hand, in a high-density recording optical disk, this distance is about 0.1 mm. When a high-density recording optical disk having two information recording layers is formed, the intermediate layer between the two information recording layers needs to be as thin as about 20 μm to 30 μm. In some cases, a lubricant layer such as a hard coat is formed on the surface of the cover layer, the surface of the cover layer is protected by the lubricant layer, and is processed smoothly. This lubricant layer is formed with a very thin thickness.

  The cover layer, the intermediate layer, and the lubricant layer described above are required to have high thickness accuracy. As a method for forming the cover layer, the intermediate layer, and the lubricant layer, a spin coating method has been proposed. The spin coating method is a method in which a liquid resin material is applied to a thin film forming surface of a substrate, and the substrate is spread at high speed around the center of the substrate by rotating the substrate at a high speed with a spin coater. . Hereinafter, the formation of the cover layer by the spin coating method will be described with reference to FIG.

  First, as shown in FIG. 8A, a liquid ultraviolet curable resin (hereinafter appropriately referred to as UV resin) 102 is dropped onto the inner periphery of the substrate 101. Next, as shown in FIG. 8B, the substrate 101 is rotated at a high speed to spread the UV resin uniformly over the entire surface of the substrate, and the excess UV resin 102 on the substrate 101 is shaken off. Thereafter, the high-speed rotation is stopped, and the UV resin 102 is cured by irradiating the substrate 101 with ultraviolet rays by the ultraviolet lamp 103 as shown in FIG. 8C. Thus, the cover layer is formed.

  However, since the spin coating method described above has a hole in the center portion, the UV resin dropping position cannot be the center position of the substrate 101, and thus a cover layer having a uniform thickness is obtained. I can't. That is, as shown in FIG. 9, the UV resin 102 applied to the substrate 101 on which the information recording layer 104 is formed becomes thicker from the inner periphery to the outer periphery, and the inner periphery and the outer periphery of about 5 μm to 10 μm. The difference in thickness occurs. Further, as indicated by reference numerals 105a and 105b, there is a problem in that the outer periphery of the substrate is raised due to the influence of the surface tension.

  In order to solve this problem, as shown in FIG. 10, a method of applying the UV resin 102 by a spin coating method in a state where the hole 111 in the center portion is closed with a cap 112 is employed. In this method, first, as shown in FIG. 10A, the substrate 101 is placed on the spinner table 113, and the hole 111 at the center of the substrate is closed with a cap 112.

  Next, as shown in FIG. 10B, while rotating the spinner table 113 on which the substrate 101 is fixed, the UV resin 102 is dropped on the center of the disk, and as shown in FIG. 10C, the uniform thickness of the UV resin 102 is obtained. A cover layer having a thickness is formed.

  Next, as shown in FIG. 10D, the rotation of the spinner is stopped. Then, as shown in FIG. 10E, the cap 112 closing the hole 111 in the center of the disk is removed, and the cap 112 is washed for reuse. As described above, the UV resin 102 is applied to the substrate 101, and a cover layer is formed on the substrate 101.

  However, when the high speed rotation of the UV resin 102 shaken off by the spin coating is stopped, the UV resin 102 on the outer peripheral portion of the substrate 101 is attracted by the surface tension of the UV resin 102 itself. That is, as shown in FIG. 11, the hole 111 in the center portion is closed with a cap 112 to prevent the height difference generated between the inner periphery and the outer periphery, so that the intermediate periphery signal area has a flat shape, but the outer periphery end 113a. And 113b will be in the form of rising several tens of μm.

  As described above, it is difficult to form a cover layer having a uniform thickness even by the spin coating method using the cap 112. Further, when the cap 112 is used, work such as cleaning of the cap 112 becomes indispensable, and workability is lowered and the apparatus becomes complicated. Further, when the cap 112 that is not sufficiently cleaned is used, a cover layer having a uniform thickness cannot be formed.

  Patent Document 1 below describes a method for preventing the bulge of the outer peripheral portion by covering the bulge with a mask. In this method, the outermost peripheral part of the substrate is covered with a light-shielding mask so that the outermost peripheral part of the substrate is not irradiated with light. Next, the photocurable resin other than the raised portion is cured. Then, the substrate is rotated again, and the photocured resin at the resin bulge portion is shaken off and removed. Next, the remaining photocurable resin is cured by irradiation with light. As a result, a resin layer having a uniform thickness is formed.

Japanese Patent Laid-Open No. 11-73691

  In the method described in Patent Document 1, if the position of the light-shielding mask is shifted even a little, ultraviolet light enters the outer peripheral bulge portion, and a uniform thickness cannot be ensured. Furthermore, even if a light-shielding mask is arranged, there is a problem in that the diffused light is irradiated to the outer peripheral bulge portion and the thickness accuracy is lowered.

  Accordingly, an object of the present invention is to provide a resin layer forming apparatus, a resin layer forming method, and an optical disc manufacturing method capable of suppressing the swell generated in the outermost peripheral portion and forming a resin layer having a uniform thickness.

  Another object of the present invention is to provide a resin layer forming apparatus, a resin layer forming method, and an optical disc manufacturing method capable of forming a resin layer having a uniform thickness without using a cap.

In order to solve the above-described problem, the present invention provides a table on which a substrate is placed and which is rotationally driven when a photocurable resin is applied on the substrate;
A light source portion disposed above the substrate and irradiating the photo-curing resin with ultraviolet rays in a spot shape, and having a light source part capable of adjusting the irradiation position of the ultraviolet rays and the moving speed during irradiation,
In the resin layer forming apparatus, the light source unit irradiates ultraviolet rays while moving in the radial direction of the substrate so that the ultraviolet rays are not irradiated near the outermost periphery of the substrate while the table is rotating.

The present invention includes a step of dripping a photocurable resin on a substrate;
While rotating the substrate to stretch the photo-curing resin on the surface of the substrate, the photo-curing resin is moved while the light source part arranged above the substrate moves in the radial direction so that the vicinity of the outermost periphery of the substrate is not irradiated with ultraviolet rays. And a step of irradiating with spot-like ultraviolet rays.

The present invention is a method of manufacturing an optical disc having a resin layer on a substrate,
Resin layer,
A light source disposed above the substrate so that the photo-curing resin is dropped on the substrate, the substrate is rotated to extend the photo-curing resin on the surface of the substrate, and ultraviolet rays are not irradiated near the outermost periphery of the substrate. A method of manufacturing an optical disc, characterized in that the portion is formed by irradiating a photo-curing resin with spot-like ultraviolet rays while moving in the radial direction.

  According to this invention, it is possible to suppress the rise of the outermost peripheral portion of the substrate, and it is possible to form a resin layer having a uniform thickness. In addition, a resin layer having a uniform thickness can be formed without using a cap.

  Embodiments of the present invention will be described below with reference to the drawings. First, an example of an optical disc to which an embodiment of the present invention can be applied will be described. FIG. 1 shows an example of a high-density recording optical disk according to an embodiment of the present invention. In this optical disc, information signals are recorded and reproduced by irradiating the information recording layer 2 with laser light from the cover layer 3 side. For example, a laser beam having a wavelength of 400 nm to 410 nm is collected by the objective lens 4 having a numerical aperture of 0.84 to 0.86 and irradiated to the information recording layer 2 from the cover layer 3 side, thereby Recording and playback are performed.

  As shown in FIG. 1, this optical disc has a configuration in which an information recording layer 2 and a cover layer 3 are sequentially laminated on one main surface of a substrate 1. The optical disk has a substantially disk shape with a center hole (not shown) opened at the center. The optical disk has, for example, a disk diameter of 120 mm, a center hole diameter of 15 mm, a disk thickness of 1.2 mm, and a substrate thickness of 1.1 mm.

  As the substrate 1, for example, a low-absorbency resin such as polycarbonate (PC) or cycloolefin polymer can be used. The information recording layer 2 is a reflective film, a recording film or the like formed on the unevenness of the substrate. The information recording layer 2 is a reflective film made of, for example, gold (Au), silver (Ag), silver alloy, aluminum (Al), aluminum alloy or the like when the optical disk is a read-only type. When the optical disc is a write-once type, the information recording layer 2 is configured by sequentially laminating a recording layer made of a reflective film and an organic dye material, for example. When the optical disc is of a rewritable type, the information recording layer 2 is configured by sequentially laminating a reflective film, a lower dielectric layer, a phase change recording layer, and an upper dielectric layer, for example.

  As the cover layer 3, a UV resin can be used. Further, if necessary, a lubricant layer (not shown) such as a hard coat may be formed on the surface of the cover layer 3. The lubricant layer is for protecting the surface of the cover layer 3 and smoothing the surface.

  Another example of a high-density recording optical disk to which an embodiment of the present invention can be applied will be described with reference to FIG. As shown in FIG. 2, the optical disc has a configuration in which an L0 layer, an intermediate layer 12, an L1 layer, and a cover layer 13 are sequentially laminated on a substrate 11. The substrate 11 is made of a low-absorbency resin such as polycarbonate (PC) or cycloolefin polymer.

  The L0 layer and the L1 layer that are information recording layers are a reflective film, a recording film, and the like formed on the unevenness of the substrate 11. The L0 layer and the L1 layer are reflective films made of, for example, gold (Au), silver (Ag), silver alloy, aluminum (Al), or aluminum alloy when the optical disk is a read-only type. When the optical disc is a write-once type, the L0 layer and the L1 layer are configured by sequentially laminating, for example, a reflective film and a recording layer made of an organic dye material. When the optical disc is a rewritable type, the L0 layer and the L1 layer are configured by sequentially laminating, for example, a reflective film, a lower dielectric layer, a phase change recording layer, and an upper dielectric layer.

  An intermediate layer 12 is formed on the L0 layer formed on the substrate 11. An L1 layer is formed on the intermediate layer 12. A cover layer 13 is formed on the L1 layer formed in the intermediate layer 12. The cover layer 13 is formed for the purpose of protecting the optical disc. Information signals are recorded and reproduced, for example, by focusing laser light on the information recording layer through the cover layer 15 by the objective lens 14.

  A UV resin can be used as the intermediate layer 12 and the cover layer 13. The thickness of the intermediate layer 12 is, for example, 25 μm, and the thickness of the cover layer 13 is, for example, 75 μm, and it is required to form a layer having a uniform thickness. For example, a UV resin and a PC sheet can be used as the cover layer 13.

  Next, a resin layer forming apparatus according to an embodiment of the present invention will be described with reference to FIG. The resin layers such as the cover layer, the intermediate layer, and the lubricant layer of the optical disk described above can be formed with a uniform thickness by this resin layer forming apparatus.

  As shown in FIG. 3, the resin layer forming apparatus includes a spinner table 21, a center pin 22, a single-axis robot 23, and a spot UV head 24 installed at the tip of the single-axis robot.

  The spinner table 21 is a table on which the substrate 31 is placed when performing spin coating. Further, the spinner table 21 rotates together with the substrate 31. The center pin 22 has a function of positioning the substrate 31 placed on the spinner table 21 and closing the opening at the center of the substrate 31.

  The spot UV head 24 is a spot UV light source unit. The spot UV head 24 is installed in the single-axis robot 23 and has a structure capable of irradiating the spot UV from the inner periphery to the outer periphery of the substrate. Here, the spot UV is ultraviolet light that irradiates the substrate with a spot in a fine range. On the surface of the substrate 31, the spot size of the spot UV is preferably about 1 mm to 10 mm in diameter, and more preferably about 2 mm to 5 mm in diameter.

  The spot UV head 24 may have a structure having a lens holder (not shown). The lens holder has a lens disposed therein, and has a structure that can be removed from the spot UV head and replaced. By exchanging the lens holder, light can be condensed, or diffused light and parallel light can be obtained. That is, the irradiation range for the substrate can be changed. Further, the spot UV may be emitted by using a power source that can be used even in a dimmed state with an inverter type.

  Next, a resin layer forming method using this resin layer forming apparatus will be described with reference to FIG. Here, an example of forming a cover layer of an optical disc will be described as an example of the resin layer.

  First, the UV resin 32 is dropped near the center of the substrate 31. Next, the spinner table 21 is rotated at a high speed, the UV resin is spread on the substrate 31 by centrifugal force, and the excess UV resin 32 on the substrate is shaken off. During this high-speed rotation, the spot UV head 24 is moved from the inner periphery to the outer periphery in the radial direction of the substrate 31 to irradiate the spot UV from the inner periphery to the outer periphery.

  Here, as shown in FIG. 4, the UV resin 32 on the substrate 31 at the time of the spinner shows a change mode depending on the irradiation amount of the ultraviolet light, the irradiation speed of the spot UV, and the rotation speed of the spinner. That is, the change modes of FIGS. 4A to 4G are shown in time series according to the rotation speed and speed. Therefore, in order to adjust the thickness of the cover layer to be uniform, an optimum spinner rotation speed and an optimum irradiation speed are selected and the spot UV is irradiated onto the UV resin 32.

  The spot UV head 24 is sent at a speed synchronized with the rotation speed of the spinner table 21. Further, the spot UV head 24 may be sent by changing the moving time without synchronizing with the rotation speed of the spinner table 21. By controlling the moving speed in the radial direction of the spot UV head 24 in this way, the thickness of the cover layer can be adjusted to an optimum thickness.

  In one embodiment, as shown in FIG. 5, the UV light 41 does not irradiate the vicinity of the outermost periphery of the substrate 31 in a state where the substrate 31 is rotated so that an uncured portion 42a is left at the outer peripheral end. The spot UV head 24 is moved. As a result, the UV resin 32 remaining on the outer peripheral edge of the substrate is shaken off by centrifugal force, and the amount of the UV resin 32 located at the outer peripheral edge of the substrate is reduced, so that the surface tension is several tens of μm. Occurrence of the bulge at the outer peripheral edge can be suppressed.

  Furthermore, in order to reliably reduce the rise at the outer peripheral edge, it is effective to increase the accuracy of the boundary where the UV light 41 is irradiated in the vicinity of the outer periphery. Specifically, for example, as shown in FIG. 6, a ring-shaped light shielding mask 51 that covers the vicinity of the outermost periphery of the substrate 31 is provided above the substrate surface with a gap therebetween.

  By combining the UV light 41 that performs spot-shaped irradiation and the light-shielding mask 51 that covers the vicinity of the outermost periphery, the UV light irradiation in the vicinity of the outermost periphery is reliably blocked, leaving the uncured portion 42b and the vicinity of the outermost periphery. It is possible to increase the accuracy of the boundary irradiated with UV light.

  As the light shielding mask 51, for example, a ring-shaped metal stencil mask having a matte black coating for suppressing surface reflection can be used. For example, the light shielding mask 51 is installed above the surface of the substrate 31 with an interval of about 1 mm.

  Furthermore, instead of the light shielding mask 51, a transmissive mask with controlled light transmission, such as a chrome mask, may be used. In the case of using a transmissive mask, a transparent circular opening having a diameter slightly shorter than the outer diameter of the substrate and the outside thereof are completely shielded from light.

  As described above, by using the UV light that performs spot-shaped irradiation and further providing the light shielding mask 51 that blocks the UV light at the outermost peripheral portion, not only the rising of the UV resin at the outer peripheral end can be suppressed. As shown in FIG. 7, the cover layer 63 formed on the information recording layer 62 can be adjusted to have a structure in which the thickness of the outer peripheral end is made thinner than the middle peripheral signal area. Furthermore, the rise of the outer peripheral portion can be stably suppressed, and as a result, a manufacturing margin can be increased.

  As described above, the above-described method secures a uniform thickness of the resin layer, and then cures by overall exposure or partial exposure of the outer peripheral edge, thereby providing excellent film thickness uniformity and the outer peripheral edge. It is possible to form a resin layer in which the swelling is suppressed.

  Next, an optical disk manufacturing method using the resin layer forming method according to one embodiment of the present invention will be described. Here, a method of manufacturing an optical disc having two information recording layers shown in FIG. 2 will be described.

  First, the board | substrate 11 is shape | molded by the injection molding which provided the uneven surface on the one main surface, for example. On the surface of the substrate 11, for example, a recording film, a reflection film, or the like is formed as an L0 layer on the concavo-convex surface by a sputtering method. Note that a recording film, a reflective film, and the like are formed on the concavo-convex surface in accordance with the reproduction type optical disc, the write-once optical disc, and the rewritable optical disc. The film configuration is different for each optical disc.

  The intermediate layer 12 is formed by applying a UV resin on one main surface of the substrate 11 and irradiating it with ultraviolet rays to be cured using the resin forming apparatus described above. The irradiation amount of ultraviolet rays when curing the UV resin is first adjusted so that the UV resin is in a semi-cured state. A resin stamper having an uneven surface for transfer is pressed against the UV resin in a semi-cured state, and the uneven surface is transferred. While maintaining the state in which the resin stamper is pressed against the ultraviolet curable resin, ultraviolet rays are irradiated from above the resin stamper to completely cure the UV resin.

  On the concavo-convex surface formed in the intermediate layer 12, a recording film, a reflection film, or the like is formed as the L1 layer by, for example, a sputtering method. Note that a recording film, a reflective film, and the like are formed on the concavo-convex surface in accordance with the reproduction type optical disc, the write-once optical disc, and the rewritable optical disc. The film configuration is different for each optical disc.

  The cover layer 13 is formed by applying a UV resin on the concavo-convex surface of the intermediate layer using the resin forming apparatus described above, and irradiating with ultraviolet rays and curing. Thus, an optical disk is manufactured.

  In one embodiment of the present invention, the cover layer, the intermediate layer, the lubricant layer, and the like of the optical disk can be easily manufactured as a uniform layer with little difference between the inner and outer circumferences. In one embodiment, it is easy to form an intermediate layer using a UV resin with a uniform thickness in the manufacture of a two-layer disc.

  Further, when the cover layer is made of UV resin, the cover layer can be easily produced with a uniform thickness. Further, even when a hard coat or the like is generally coated on the surface for protecting the cover layer, it can be easily produced with a uniform thickness. Furthermore, a high-density recording optical disk can be manufactured without a center cap by a method using a UV resin.

  Furthermore, the inclination of the cover layer (thickness difference between the inner and outer circumferences) can be controlled. For example, when the spot UV is irradiated from the inner periphery to the outer periphery at a high speed, the inner periphery can be adjusted to be thick and the outer periphery can be adjusted to be thin. When the spot UV is irradiated from the inner periphery to the outer periphery at a slow speed, the inner periphery is thin and the outer periphery can be adjusted to be thick. Therefore, the film thickness can be controlled by controlling the moving speed of the spot UV.

  The present invention is not limited to the above-described embodiment of the present invention, and various modifications and applications can be made without departing from the gist of the present invention. For example, in the optical disc according to the above-described embodiment, the description has been given by taking the single-layer optical disc and the single-sided dual-layer optical disc as examples. However, the present invention is not limited thereto. It is also applicable to.

  In the above-described embodiment, the substrate is fixed to the spinner table using the center pin, but may be fixed using means such as vacuum suction.

  Further, the material used for the resin layer forming apparatus according to the embodiment of the present invention is not limited to the UV resin, and other thin film forming coating materials such as an adhesive can be used. Furthermore, although the resin layer forming apparatus according to the embodiment of the present invention has been described as forming the resin layer on the substrate of the optical disk, the object to be coated is not limited to this.

It is sectional drawing which shows an example of the optical disk by one Embodiment of this invention. It is sectional drawing which shows the other example of the optical disk by one Embodiment of this invention. It is the schematic which shows the resin layer forming apparatus by one Embodiment of this invention. It is the schematic which shows the motion of UV resin at the time of a spinner. It is the schematic which shows an example of the resin layer forming method by one embodiment of this invention. It is the schematic which shows the other example of the resin layer formation method by one Embodiment of this invention. It is a schematic sectional drawing which shows the example of the resin layer by one embodiment of this invention. It is the schematic which shows the conventional spin coat method. It is a schematic sectional drawing which shows an example of the conventional resin layer. It is the schematic which shows the spin coat method using a center cap. It is a schematic sectional drawing which shows the other example of the conventional resin layer.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Substrate 2 ... Information recording layer 3 ... Cover layer 4 ... Objective lens 11 ... Substrate 12 ... Intermediate layer 13 ... Cover layer 14 ... Objective lens 15 ... Cover layer 21 ... Spinner table 22 ... Center pin 23 ... Single axis robot 24 ... Spot UV head 31 ... Substrate 32 ... UV resin 42a, 42b ... Uncured part 51 ... Shading mask

Claims (6)

A table on which a substrate is placed and driven to rotate when applying a photo-curing resin on the substrate;
A light source unit disposed above the substrate and irradiating the photo-curing resin with ultraviolet rays in a spot shape, and having an ultraviolet irradiation position and a moving speed during irradiation adjustable.
The resin layer forming apparatus, wherein the light source unit irradiates the ultraviolet rays while moving in the radial direction of the substrate so that the ultraviolet rays are not irradiated near the outermost periphery of the substrate during rotation of the table. . In claim 1,
A resin layer forming apparatus comprising a mask covering the vicinity of the outermost periphery of the substrate. In claim 1,
The resin layer forming apparatus, wherein the light source unit includes a removable lens holder in which a lens is disposed. Dropping a photocurable resin on the substrate;
The light source part arranged above the substrate moves in the radial direction so that the substrate is rotated and the photo-curing resin is stretched on the surface of the substrate, and ultraviolet rays are not irradiated near the outermost periphery of the substrate. And a step of irradiating the photocured resin with spot-like ultraviolet rays. In claim 4,
A method for forming a resin layer, characterized by covering the vicinity of the outermost periphery of the substrate with a mask. A method of manufacturing an optical disc having a resin layer on a substrate,
The resin layer
A photo-curing resin is dropped on the substrate, the substrate is rotated to extend the photo-curing resin on the surface of the substrate, and ultraviolet rays are not irradiated near the outermost periphery of the substrate. A method for producing an optical disc, comprising: forming a light source portion disposed above by irradiating the photocurable resin with spot-like ultraviolet rays while moving in a radial direction.

Images