JP2009043330A - Manufacturing method of optical disk - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a manufacturing method of an optical disk capable of preventing generation of deformation, distortion and wrinkles of a sheet-shaped substrate member and a rugged pattern and forming the rugged pattern nearly free from eccentricity. <P>SOLUTION: According to the manufacturing method of the optical disk, formation of the rugged pattern to the sheet shaped substrate member 80 can be performed at a temperature lower than a glass transition point by providing a base member 90 and generation of deformation, distortion and wrinkles can be prevented. Since a punch of the sheet-shaped substrate member 80 is performed when the rugged pattern is transferred to the sheet-shaped substrate member 80, a center position of a thin layer substrate and a nearly center position of the rugged pattern can be made coincident with each other and the thin layer substrate B having the rugged pattern nearly free from eccentricity can be manufactured. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a method of manufacturing an optical disc in which information signals are reproduced or recorded by irradiating laser light from the outside, and in particular, an optical disc capable of forming an uneven pattern with less deformation and distortion on a thin substrate sheet. It relates to a manufacturing method.

  As recording media for acoustic data, image data, and other digitized information signals, recording and reproduction of information signals by irradiating laser light from the outside in terms of recording capacity, random accessibility, portability, price, etc. Optical discs that are used are widely spread from industrial use to consumer use. As these optical discs, reproduction-only types such as CD (Compact Disc) and DVD (Digital Versatile Disc), write-once types such as CD-R and DVD-R, which can be recorded only once, CD-RW, DVD-RW, etc. Various rewritable types such as DVD-RAM, which can be recorded any number of times, and BD (Blu-ray Disc) have been developed as large-capacity optical discs.

  These optical discs have an information surface for recording information signals, and this information surface is generally composed of a fine concavo-convex pattern and a functional layer formed along the concavo-convex pattern. In the read-only optical disc, the above-described concave / convex pattern is constituted by pit rows, and in the recordable / rewritable optical disc such as a write once type / rewritable type, it is constituted by guide grooves such as grooves and lands. These uneven patterns are arranged concentrically or spirally on the information surface of the optical disk. The reproduction of information signals recorded on these optical discs reflects the laser beam incident from the incident surface of the optical disc on the information surface, and the intensity of the reflected light differs depending on the presence or absence of pits or the presence or absence of recording marks formed in the guide grooves. Determine that.

  In recent years, information communication, image processing technology, and the like have been developed rapidly, and the amount of information processed accordingly has increased dramatically. In order to cope with the increase in the amount of information, the optical disc is required to have a higher recording capacity. In order to increase the recording capacity of an optical disc, it is effective to further refine the uneven pattern formed on the information surface and increase the recording density on the information surface.

  However, in the above-described method for increasing the recording density on the information surface, it is necessary to reduce the spot diameter of the laser beam irradiated in accordance with the miniaturized guide grooves and pits. Generally, the spot diameter is reduced by shortening the wavelength of the laser beam and increasing the numerical aperture NA of the objective lens for irradiating the laser beam.

  However, when the numerical aperture NA of the objective lens is increased, the depth of focus of the laser light becomes shallow, and the allowable amount of the angle (tilt angle) at which the information surface of the optical disk deviates from the perpendicular to the optical axis of the laser light becomes small. The problem arises. For this reason, in order to make the concavo-convex pattern fine and improve the recording density on the information surface, it is necessary to shorten the distance from the laser light incident surface to the information surface in the optical disk.

  For example, in the above-mentioned BD, by miniaturizing the shortest pit length to 0.15 μm and the track pitch to 0.32 μm, using a blue laser beam having a wavelength of 405 nm and an objective lens having a numerical aperture NA of 0.85, A high recording capacity of 25 gigabytes per side is achieved. The distance from the incident surface to the information surface in this BD is about 0.1 mm, which is 1/6 of DVD.

  However, it is difficult to reduce the wavelength of the laser beam beyond this and increase the numerical aperture NA of the objective lens with the current technical level, and the actual situation is that the increase in capacity of the optical disk by miniaturization of the concave / convex pattern has reached its limit. It is. For this reason, in order to further increase the capacity of the optical disk, a multilayer technology for stacking a plurality of information surfaces in a three-dimensional direction has been developed, and a high-capacity optical disk having a plurality of information surfaces with a high recording density has already been put into practical use. Yes.

  By the way, the concavo-convex pattern constituting the information surface of the optical disc is generally formed at the same time as the substrate molding using an injection molding method. However, when a plurality of information surfaces having a high recording density are formed on an optical disc, the concave / convex pattern on the information surface (this is the first information surface) located on the far side (back side) from the laser light incident surface is the same as before. Although it is possible to form by using an injection molding method, it is necessary to form an uneven pattern on the information surface (this is the second information surface) located on the side closer to the laser light incident surface (front side). It is difficult to use a molding method. This is because the distance from the incident surface to the first information surface is too short, and it is difficult to form a fine uneven pattern on such a thin substrate with high accuracy by the injection molding method.

  Here, in [Patent Document 1] below, a second information surface is formed between the incident surface of the optical disc and the first information surface on the back side using a radiation curable resin and a resin stamper having optical transparency. The invention is disclosed. In the invention disclosed in [Patent Document 1], first, a radiation curable resin is applied on a first information surface of a first substrate or a flat thin substrate formed by a conventional injection molding method or the like. Next, a light-transmitting resin stamper on which the master pattern of the concave / convex pattern of the second information surface located on the near side is pressed against the applied radiation curable resin layer, and predetermined radiation is irradiated through the resin stamper. . Thereby, the radiation curable resin is cured, and a concavo-convex pattern of the second information surface is formed on the cured radiation curable resin layer. And when the uneven | corrugated pattern of the 2nd information surface was formed on the 1st information surface, after forming a predetermined functional layer on this uneven | corrugated pattern, a protective layer was formed on this functional layer, and two layers were formed. An optical disc having an information surface is produced. Further, when the concave / convex pattern of the second information surface is formed on the thin substrate, after forming a predetermined functional layer on the concave / convex pattern, the thin substrate having the second information surface and the substrate having the first information surface And an optical disc having a two-layer information surface.

  However, the above-mentioned resin stamper is inferior in durability to the metal stamper, and there is a problem that the number of substrates that can be manufactured with one resin stamper is small and the manufacturing efficiency is low.

  Further, when the second information surface is formed on the first information surface of the first substrate using the invention disclosed in [Patent Document 1], the formed second information surface is a laser from the functional layer side. Light will enter. In general, the concave / convex pattern shape of the functional layer is inferior to the concave / convex pattern shape formed on the substrate. Therefore, reading the information signal from the functional layer side like the above-mentioned optical disc does not improve the quality of the reproduced signal. It is not preferable from the viewpoint. By using the invention disclosed in [Patent Document 1], a concave / convex pattern of the second information surface is formed on a thin substrate, and after the functional layer is formed, this is reversed and bonded to the first substrate. In this case, the incident surface of the laser light can be the substrate side. However, in this case, the handling property for the thin substrate after the formation of the concave-convex pattern is extremely poor, and it is necessary to form the functional layer and bond with the first substrate after being held by a reinforcing member such as a support substrate. In addition to being complicated, the production efficiency is also poor.

  In this regard, in the invention disclosed in the following [Patent Document 2], the concave / convex pattern is formed by pressing the stamper against the sheet-like substrate member heated to a temperature equal to or higher than the glass transition point. For this reason, it is possible to use a metal stamper having excellent durability, and the manufacturing efficiency is high. In addition, since the functional layer is continuously formed, the protective layer is formed, and the optical disk is punched into the shape of the optical disc after forming the concavo-convex pattern, the handling property is excellent.

JP 2002-260307 A JP-A-11-185291

  However, generally, when the sheet-like substrate member is heated to a temperature equal to or higher than the glass transition point, the sheet-like substrate member is softened and the transferability is improved, but the sheet-like substrate member may be wrinkled or distorted. Furthermore, in the invention disclosed in [Patent Document 2], the uneven pattern is formed in a state where the sheet-like substrate member is pulled in the longitudinal direction. There is a possibility of exhibiting an elliptical shape deformed in the longitudinal direction of the substrate member. Such a deformed concavo-convex pattern makes it difficult to follow the laser beam with high accuracy, and there is a possibility that the performance as an optical disk is significantly deteriorated, and further improvement is desired.

  In the invention disclosed in [Patent Document 2], the punching of the sheet-like substrate member is performed in a separate process after the formation of the concavo-convex pattern. As described above, when the concave / convex pattern forming step and the sheet-shaped substrate member punching step are temporally and spatially separated, there is a possibility that a deviation occurs between the center position of the optical disc and the substantially central position of the concave / convex pattern. The information surface on which the concave / convex pattern having such a shifted center position is eccentrically rotated from the center position of the optical disc, and similarly, it is difficult to follow the laser beam with high accuracy, and further improvement is desired. The deviation between the center position of the optical disc and the substantially center position of the concave / convex pattern is referred to as eccentricity here.

  The present invention has been made in view of the above circumstances, and is an optical disc capable of preventing the deformation, distortion, and wrinkle generation of a sheet-like substrate member and a concavo-convex pattern and forming a concavo-convex pattern with less eccentricity. An object is to provide a manufacturing method.

The present invention
(1) In an optical disc manufacturing method for manufacturing an optical disc by forming an uneven pattern on a sheet-like member heated to a predetermined transfer temperature and then bonding the sheet-like member and a substrate thicker than the sheet-like member.
One side of the sheet-like member (sheet-like substrate member 80) is held by a base member 90 having a hardness lower than the hardness of the sheet-like member at the transfer temperature, and the other side of the sheet-like member is A heating step of placing a stamper 26 that has a concavo-convex pattern (matrix 22a) as a matrix of the concavo-convex pattern 22 and presses the concavo-convex pattern against the sheet-like member, and heating the sheet-like member to the transfer temperature; ,
In a state where the stamper 26 is pressed against the sheet-like member heated to the transfer temperature in the heating step, the sheet-like member and the base member 90 are punched into a predetermined shape, and the other side of the sheet-like member is Forming a concavo-convex pattern 22 and forming an adhesion structure having the predetermined shape in which the sheet-like member and the base member 90 are detachably adhered; and
A film forming step of forming a functional film (functional layer) having a predetermined function on the uneven pattern 22 after the adhesion structure forming step;
After the film formation step, a bonding step of bonding the sheet-like member (thin layer substrate B) and the substrate (disk substrate A) in the adhesion structure;
After the bonding step, a peeling step of peeling the base member 90 from the adhesion structure;
Have
The above-mentioned problem is solved by providing a method of manufacturing an optical disc, wherein the transfer temperature in the heating step is lower than the glass transition temperature of the sheet-like member.
(2) In an optical disc manufacturing method for manufacturing an optical disc by forming an uneven pattern on a sheet-like member heated to a predetermined transfer temperature and then bonding the sheet-like member and a substrate thicker than the sheet-like member.
A film forming step of forming a functional film (functional layer) having a predetermined function on one surface side of the sheet-like member (sheet-like substrate member 80);
After the film forming step, one surface side of the sheet-like member is held by a base member 90 having a hardness lower than the hardness of the sheet-like member at the transfer temperature, and the unevenness is formed on the other surface side of the sheet-like member. A heating step of placing a stamper 26 having a concavo-convex pattern (matrix 22a) as a matrix of the pattern 22 and pressing the concavo-convex pattern against the sheet-like member, and heating the sheet-like member to the transfer temperature;
The sheet-like member and the base member 90 are punched into a predetermined shape while the stamper 26 is pressed through the functional film against the sheet-like member heated to the transfer temperature in the heating step, and the sheet Forming the concave-convex pattern 22 covered with the functional film on one surface side of the sheet-like member, and forming an adhesion structure having the predetermined shape in which the sheet-like member and the base member 90 are detachably adhered A structure forming step;
A bonding step of bonding the sheet-like member (thin layer substrate B) and the substrate (disk substrate A) in the adhesion structure after the adhesion structure forming step;
After the bonding step, a peeling step of peeling the base member 90 from the adhesion structure;
Have
The above problem is solved by providing a method of manufacturing an optical disc, wherein the transfer temperature in the heating step is lower than the glass transition temperature of the sheet-like member.
(3) The transfer temperature according to (1) or (2) above, wherein the transfer temperature is a temperature not lower than a glass transition temperature of the base member 90 or a temperature not lower than a melting point of the base member 90. The above problem is solved by providing a method for manufacturing an optical disc.

According to the optical disc manufacturing method of the present invention, the above procedure
(1) Since the concavo-convex pattern can be formed at a temperature lower than the glass transition point of the sheet-like substrate member, it is possible to prevent the sheet-like substrate member and the concavo-convex pattern from being deformed, distorted and wrinkled. Thereby, it is possible to produce a good optical disk that can follow the laser light with high accuracy.
(2) Further, since the sheet-like substrate member is punched when forming the concavo-convex pattern, a good optical disc having a concavo-convex pattern (information surface) with less eccentricity in which the center position of the optical disc matches the substantially central position of the concavo-convex pattern Can be produced.

  Embodiments of an optical disk manufacturing method according to the present invention will be described with reference to the drawings. Here, an explanation will be given by taking an optical disc having two layers of information as an example. FIG. 1 is a schematic cross-sectional view of an optical disc having two layers of information surfaces. 2, FIG. 4, and FIG. 5 are schematic cross-sectional views for explaining an embodiment of an optical disk manufacturing method according to the present invention. FIG. 3 is a graph showing the relationship between the temperature and hardness of the sheet-like substrate member and the base member. FIG. 6 is a schematic configuration diagram of a stamper press suitable for the optical disk manufacturing method according to the present invention. FIG. 7 is a partially enlarged view of a stamper press suitable for the optical disk manufacturing method according to the present invention. FIG. 8 is a schematic cross-sectional view showing an example of an optical disk to which the optical disk manufacturing method according to the present invention is applied.

  First, FIG. 1 shows a schematic cross-sectional view of an optical disc D that can be produced by the method for producing an optical disc according to the present invention. The optical disc D includes a thick first substrate 11 (disc substrate A) provided with a first information surface 14, a second substrate 21 (thin layer substrate B) thinner than that provided with a second information surface 24, and a first substrate. A light-transmitting adhesive layer 16 provided between the information surface 14 and the second information surface 24 is formed so as to penetrate the first substrate 11, the second substrate 21, and the adhesive layer 16. And a center hole 15 for mounting the optical disk D in the recording / reproducing apparatus. The first information surface 14 of the first substrate 11 is composed of the concave / convex pattern 12 and the first functional layer 13, and the second information surface 24 of the second substrate 21 is the concave / convex pattern 22 and the second functional layer. 23. The above is the main component of the optical disc D having two information surfaces, the first information surface 14 and the second information surface 24.

  The concavo-convex pattern 12 and the concavo-convex pattern 22 are composed of pit rows of a predetermined size when the optical disc D is a read-only type, and are guide grooves such as grooves and lands when the optical disc D is a write-once type or a rewritable type. Composed. Further, the concave / convex pattern 12 and the concave / convex pattern 22 are formed concentrically or spirally on the information surfaces of the first substrate 11 and the second substrate 21, and their approximate center positions and the centers of the first substrate 11 and the second substrate 21. The position is almost the same position.

  In the case of the aforementioned BD, the diameter of the optical disk D is 120 mm, the diameter of the center hole 15 is 15 mm, the thickness of the first substrate 11 is about 1.1 mm, and the thickness of the second substrate 21 is about 1.1 mm. By setting the thickness to 0.1 mm, the total thickness of the optical disk D is set to about 1.2 mm. Further, the surface on the second substrate 21 side is a laser light incident surface, and the surface on the first substrate 11 side is a label surface on which a title label or the like is formed.

  Next, an optical disk manufacturing method according to an embodiment of the present invention will be described using the optical disk D shown in FIG. 1 as an example. The optical disk manufacturing method according to the present invention is particularly characterized by the method of manufacturing the second substrate 21 which is the thin layer substrate B in the optical disk D. Therefore, here, the description will focus on the method of forming the second information surface 24 on the second substrate 21, but the method of manufacturing the optical disc according to the present invention is not particularly limited to the formation of the second information surface. The present invention can also be applied to formation of each information surface in a single-layer or two-layer or more optical disc.

  First, as shown in FIG. 2A, for example, a sheet shape wound in a rectangular shape or a roll shape as a base of the second substrate 21 at a predetermined position of a substrate molding machine such as a stamper press machine 30 described later. The substrate member 80 and the base member 90 wound in the same rectangular shape or roll shape are overlapped and installed. As the substrate molding machine here, it is possible to heat the sheet-like substrate member 80, the base member 90, and the metal stamper 26 in which the matrix 22a of the concave-convex pattern 22 is formed on one surface to a predetermined temperature. A combination of heating means and pressing means capable of pressing the stamper 26 against the sheet-like substrate member 80 is used. When the stamper press machine 30 is used as the substrate molding machine, the sheet-like substrate member 80 and the base member 90 are between the movable die 32 and the fixed die 34, and the mother die 22a of the stamper 26 installed in the movable die 32. And the sheet-like substrate member 80 are arranged to face each other.

  As a material of the sheet-like substrate member 80, a glass having a sufficient light transmittance with respect to a laser beam having a specific wavelength used for recording and reproduction of the optical disc D and an appropriate temperature range (preferably a temperature range of 80 ° C. to 200 ° C.). A synthetic resin having a transition temperature is suitable, and specific examples include polycarbonate, acrylic, poreolyfin, PET (polyethylene terephthalate), PEN (polyethylene naphthalate), and the like.

  The width and length of the sheet-like substrate member 80 are not particularly limited as long as they are equal to or larger than the diameter of the optical disc D, but a relatively large one is used with respect to the diameter of the optical disc D, and used when punching in the surplus area. It is preferable to provide an alignment marker for alignment and a region used for fixing and adsorbing the sheet-like substrate member 80. Further, it is preferable that the thickness of the sheet-like substrate member 80 is equal to that of the second substrate 21 and the thickness thereof is uniform. Further, a protective film is provided in close contact with the surface of a general sheet-like substrate member 80, and it is preferable that this protective film is peeled off immediately before being installed in the substrate molding machine from the viewpoint of preventing foreign matter adhesion. .

  As the material of the base member 90, a thermoplastic resin whose hardness at a transfer temperature described later is lower than that of the sheet-like substrate member 80, specifically, the Shore D hardness at normal temperature is in the range of 20 to 70. There are polyethylene film, polyester film, cyclopolyolefin and the like.

  The width and length of the base member 90 are not particularly limited as long as they are equal to or larger than the diameter of the optical disc D, but are preferably equal to the sheet-like substrate member 80. The thickness of the base member 90 is not particularly limited, but is preferably in the range of 1/2 to 2 times the thickness of the sheet-like substrate member 80, particularly equal to the thickness of the sheet-like substrate member 80. In addition, it is preferable that the surface state of the surface of the base member 90, particularly the surface in contact with the sheet-like substrate member 80, is a smooth or fine textured surface, and if there are large unevenness on the surface of the base member 90, This is because the unevenness is transferred to the sheet-like substrate member 80 and adversely affects the characteristics of the optical disc D. Further, if the surface state of the base member 90 is set to the embossed state, it is possible to prevent air from being caught between the base member 90 and the sheet-like substrate member 80.

  Next, the sheet-like substrate member 80 and the base member 90 are heated and held at a predetermined transfer temperature or a temperature in the vicinity thereof by the heating means of the substrate molding machine. The transfer temperature at this time is lower than the glass transition point of the sheet-like substrate member 80, and the hardness of the base member 90 at this transfer temperature is lower than the hardness of the sheet-like substrate member 80 at this transfer temperature. To do. More specifically, the transfer temperature is set to a temperature 5 to 80 ° C., preferably 10 to 40 ° C. lower than the glass transition point of the sheet-like substrate member 80, and higher than the glass transition point of the base member 90. It is preferable to do. If the transfer temperature is too lower than the glass transition point of the sheet-like substrate member 80, the polymer constituting the sheet-like substrate member 80 is not softened and flowed smoothly, and the transferability of the concavo-convex pattern is deteriorated. Further, if the transfer temperature is in the vicinity of the glass transition point of the sheet-like substrate member 80, cooling takes time and productivity is lowered. Therefore, it is necessary to set the transfer temperature in consideration of these points. The above corresponds to the heating step.

  Next, as shown in FIG. 2B, the sheet-like substrate member 80 heated and held at a predetermined transfer temperature or a temperature in the vicinity thereof is similarly heated and held at a predetermined transfer temperature or a temperature in the vicinity thereof. The stamper 26 is pressed with a predetermined pressure. Then, by maintaining this state for a predetermined time, the master die 22a of the stamper 26 is transferred to one surface of the sheet-like substrate member 80, and the base member 90 is brought into close contact with the opposite surface. At this time, the sheet-like substrate member 80 is punched into a predetermined disk shape together with the base member 90.

  Next, after the sheet-like substrate member 80, the base member 90, the stamper 26, and the like are cooled to a predetermined temperature, the pressing of the stamper 26 against the sheet-like substrate member 80 is released. As a result, as shown in FIG. 2C, the uneven pattern 22 is formed on the sheet-like substrate member 80, and the sheet-like substrate member 80 has a predetermined inner and outer diameter size while the base member 90 is in close contact therewith. The second substrate 21 having the center hole 15 is punched out. The above corresponds to the adhesion structure forming step.

  As described above, the optical disk manufacturing method according to the present invention does not transfer the concave / convex pattern by viscous deformation by heating the sheet-like substrate member 80 to a temperature equal to or higher than the glass transition point as in the prior art. The concavo-convex pattern is transferred by elastic plastic deformation by heating to a relatively low temperature below.

  Here, FIG. 3 shows the relationship between the temperature and hardness of the sheet-like substrate member 80 and the base member 90. In FIG. 3, curve A represents the hardness curve of the sheet-like substrate member 80, curve B represents the hardness curve of the base member 90, Tg represents the glass transition temperature of the sheet-like substrate member 80, and Tg ′ represents The glass transition temperature of the base member 90 shall be shown. From FIG. 3, the hardness of the sheet-like board | substrate member 80 will fall rapidly, if the glass transition point Tg is exceeded. Therefore, when the concavo-convex pattern is transferred at a temperature equal to or higher than the glass transition point Tg, the transferability is good, but on the other hand, deformation, distortion, wrinkles and the like are likely to occur in the sheet-like substrate member 80. In addition, when the concavo-convex pattern is transferred at a temperature lower than the glass transition point Tg, deformation, distortion, wrinkles and the like are difficult to occur, but the transferability of the concavo-convex pattern deteriorates because the hardness of the sheet-like substrate member 80 is high. .

  For this reason, in the optical disk manufacturing method according to the present invention, the base member 90 whose hardness at the transfer temperature is lower than the hardness of the sheet-like substrate member 80 is disposed under the sheet-like substrate member 80. By disposing the base member 90, the base member 90 becomes a deformation region (escape region) of the sheet-like substrate member 80 when the stamper 26 is pressed, and the sheet-like substrate member 80 has a temperature region lower than the glass transition point Tg. Even in this case, excellent transferability can be obtained. This is particularly noticeable when the transfer temperature is lower than the glass transition point Tg of the sheet-like substrate member 80 and higher than the glass transition point Tg ′ of the base member 90. The base member 90 may be melted at the time of transfer. In this case, the buffering property of the base member 90 is increased, and the transfer property is further improved.

  Further, the pressing force of the stamper 26 is uniformly applied to the sheet-like substrate member 80 by the base member 90, and uneven transfer to the sheet-like substrate member 80 can be reduced. Further, due to the effect of reducing the transfer unevenness by the base member 90, it is possible to omit the adjustment work of the parallelism between the stamper 26 and the fixed die 34, which has been performed every time the stamper 26 is replaced. Furthermore, by providing the base member 90, it is possible to prevent the sheet-like substrate member 80 from adhering to the fixed mold 34 side and to improve the peelability. At this time, if the base member 90 is likely to adhere to the fixed mold 34 side, a release agent may be applied between the base member 90 and the fixed mold 34 or a release sheet may be provided. Since the base member 90 is peeled and removed in a later step, the surface condition of the release agent or the release sheet does not adversely affect the second substrate 21.

  Further, in the method for manufacturing an optical disk according to the present invention, the stamper 26 is pressed against the sheet-like substrate member 80 to transfer the concavo-convex pattern 22, and the sheet-like substrate member 80 and the base member 90 are punched. As a result, it is possible to form, on the second substrate 21 (thin layer substrate B), the concavo-convex pattern 22 with little eccentricity in which the substantially center of the concavo-convex pattern 22 substantially coincides with the center of the second substrate 21.

  Next, the second substrate 21 produced by the adhesion structure forming step is removed from the substrate molding machine such as the stamper press machine 30 while the base member 90 is in close contact, and as it is, as shown in FIG. In addition, the second functional layer 23 is formed on the concave / convex pattern 22 of the second substrate 21. In addition, since the base member 90 that is in close contact with the second substrate 21 functions as a reinforcing member, the handling property with respect to the second substrate 21 is good, and a special process for closely adhering the reinforcing member is not required, so that the production efficiency is also reduced. There is nothing.

  For the film formation of the second functional layer 23, a well-known film formation method such as a vacuum evaporation method using an electron beam heating method, a resistance heating method, and a laser heating method, or a sputtering method such as a direct current sputtering method or a high frequency sputtering method is used. Can be used.

In addition, when the optical disk D to be manufactured is a read-only type, the second functional layer 23 is a simple substance such as Al (aluminum), Ag (silver), Au (gold), Cu (copper), Si (silicon), Or it is comprised with the reflective film which has a translucency which consists of an alloy or these oxides, nitride, carbide | carbonized_material, etc. When the optical disk D to be manufactured is a rewritable or write-once type, for example, a well-known dielectric film such as ZnS (zinc sulfide) -SiO ₂ (silicon dioxide) and Ge—Sb—Te (germanium / ammotine / tellurium) are used. ) System or Sb—Te system and other semi-transparent recording films made of a known phase change material, and a plurality of films made of the above-described known reflective films. Further, when the optical disk D to be manufactured is a write-once optical disk using an organic dye, the second functional layer 23 includes an organic dye film in which a known organic dye is formed by a spin coat method or a wet coater, and the aforementioned known reflection. It is composed of a plurality of films composed of films. The uneven pattern 22 and the second functional layer 23 constitute the second information surface 24 of the second substrate 21. The above corresponds to the film forming process.

  Next, the first substrate 11 (disk substrate A) having the first information surface 14 manufactured separately and the second substrate 21 having the second information surface 24 are bonded to each other. The material of the first substrate 11 is a resin material such as polycarbonate, acrylic or poreolyfin, or a ceramic material such as glass. In particular, when the resin material is used, the first substrate 11 is injection-molded together with the concavo-convex pattern 12. It is preferable to prepare by the method. Further, the first functional layer 13 is formed on the concave-convex pattern 12 of the first substrate 11 in the same manner as the second functional layer 23, and the first information surface 14 is formed. In addition, the 1st board | substrate 11 and the 1st functional layer 13 do not need to have a light transmittance in particular.

  For example, the first substrate 11 and the second substrate 21 are joined as follows. First, the central hole 15 of the first substrate 11 is inserted into the central axis of the spin coater so that the first information surface 14 faces upward. While rotating this at a low speed, an ultraviolet curable resin is dropped onto the inner peripheral portion of the first substrate 11, and then the central hole 15 of the second substrate 21 is placed on the central axis of the spin coater so that the second information surface 24 faces downward. Drop it. Next, the first substrate 11 and the second substrate 21 are rotated at a high speed, and the dropped ultraviolet curable resin is spread uniformly in the gap between the first substrate 11 and the second substrate 21. At this time, the viscosity of the ultraviolet curable resin may be adjusted by heating with an infrared lamp or the like. Next, the rotation of the spin coater is stopped, and ultraviolet rays are irradiated to cure the ultraviolet curable resin. As a result, as shown in FIG. 4B, the cured ultraviolet curable resin becomes the adhesive layer 16, and the first substrate 11 having the first information surface 14 and the second substrate 21 having the second information surface 24. Are bonded so that the first information surface 14 and the second information surface 24 face each other. The above corresponds to the bonding step.

  The first substrate 11 and the second substrate 21 may be joined using a thermosetting resin that is cured by heating or using a sheet-like pressure-sensitive adhesive. In the case where a sheet-like pressure-sensitive adhesive is used for joining the first substrate 11 and the second substrate 21, the pressure-sensitive adhesive cut out in a shape substantially the same as the first substrate 11 is used as the first adhesive of the first substrate 11. The pressure is applied on the information surface 14 and then the second substrate 21 is pressed and bonded to the pressure-sensitive adhesive.

  Finally, as shown in FIG. 4C, the base member 90 that is in close contact with the second substrate 21 is physically peeled off by vacuum suction or the like. Thereby, an optical disc D having a two-layer information surface is produced. The above corresponds to the peeling step. The base member 90 also has a function as a protective sheet that protects the incident surface of the optical disc D from scratches and dust until it is peeled off. Therefore, it is preferable to peel off the base member 90 at the end of the process from the viewpoint of preventing external damage to the optical disc D and the adhesion of foreign matter.

  The second substrate 21 may be manufactured by the following procedure. First, as a film forming process, as shown in FIG. 5A, the second functional layer 23 is formed on one surface of the sheet-like substrate member 80 by a known film forming method such as a vacuum evaporation method or a sputtering method. . When the sheet-like substrate member 80 is wound in a roll shape, the second functional layer 23 is formed while sequentially feeding the sheet-like substrate member 80, and the sheet-like substrate member 80 is wound after the film formation. Try to take. When the second functional layer 23 is composed of a plurality of films, the above operation is performed for each film.

  Next, the sheet-like substrate member 80 on which the second functional layer 23 is formed and the base member 90 are installed in a substrate molding machine such as the stamper press machine 30. At this time, the second functional layer 23 side of the sheet-like substrate member 80 is the side where the stamper 26 is installed, and the base member 90 is positioned on the opposite side where the second functional layer 23 is not formed. Next, as shown in FIG. 5B, the concave / convex pattern 22 is formed by pressing the stamper 26 having the mother die 22a with a predetermined pressure on the second functional layer 23 formed on the sheet-like substrate member 80 for a predetermined time. To do. At this time, the temperatures of the sheet-like substrate member 80 and the base member 90 are heated to the transfer temperature described above. At this time, the sheet-like substrate member 80 is punched into the shape of the second substrate 21 together with the base member 90.

  After these members are cooled to a predetermined temperature, the pressing by the stamper 26 is released. As a result, as shown in FIG. 5C, the second substrate 21 having the second information surface 24 to which the base member 90 is in close contact is manufactured. The above corresponds to the heating step and the adhesion structure forming step.

  The second substrate 21 produced by the adhesion structure forming process becomes the optical disc D having the two-layer information surface through the bonding process and the peeling process.

  According to the optical disk manufacturing method in which the film forming step is performed first, the second functional layer 23 can be continuously formed, particularly when the sheet-like substrate member 80 is in the form of a roll. high.

  Next, the structure and operation of the stamper press 30 suitable for the heating process and the adhesion structure forming process of the optical disk manufacturing method according to the present invention will be described with reference to FIGS. The stamper press machine 30 shown in FIG. 6 has a movable mold 32 and a fixed mold 34, and the movable mold 32 is connected to, for example, a pressure cylinder 36 as a pressing means. A plurality of guide rods 38 parallel to each other are provided between the fixed die 34 and the pressure cylinder 36, and the movable die 32 is fitted into the guide rod 38 in a movable state. Therefore, the movable mold 32 can be moved forward or backward in the direction of the fixed mold 34 along the guide rod 38 by the operation of the pressure cylinder 36. The pressurizing cylinder 36 may be operated by any driving mechanism such as hydraulic pressure, pneumatic pressure, or motor driving.

  A temperature adjuster 42a and a temperature sensor 44a are provided on a pedestal 40a disposed on the fixed mold 34 side of the movable mold 32. The temperature sensor 44a measures the temperature of the pedestal 40a and outputs the measured temperature to the feedback circuit 46a. The feedback circuit 46a controls a heater and cooling pipe (not shown) embedded in the pedestal 40a via the temperature controller 42a. Predetermined temperature rise, heat retention, and cooling operations for 40a are performed. The stamper 26 is attached to the surface of the base 40a on the fixed mold 34 side.

  Further, a pedestal 40b disposed on the movable mold 32 side of the fixed mold 34 is provided with a temperature controller 42b and a temperature sensor 44b. The temperature sensor 44b measures the temperature of the pedestal 40b and outputs the measured temperature to the feedback circuit 46b. The feedback circuit 46b controls a heater or cooling pipe (not shown) embedded in the pedestal 40b via the temperature controller 42b. Predetermined temperature rise, heat retention, and cooling operations for 40b are performed. The fixed die 34 may be provided with a correction plate 56 having a triangular cross section for maintaining parallelism with the movable die 32 at the base of the base 40b.

  Next, the bases 40a and 40b of the stamper press 30 will be described in more detail with reference to FIG. In FIG. 7, the description of the temperature sensors 44a and 44b is omitted.

  FIG. 7 is a partially enlarged view of the pedestals 40 a and 40 b of the movable mold 32 and the fixed mold 34 of the stamper press machine 30. The pedestal 40a shown in FIG. 7A has a movable base plate 58a and a stamper block 60, and a temperature adjustment groove 62a for accommodating a heater and a cooling pipe constituting the temperature controller 42a in the stamper block 60. Is provided.

  The pedestal 40b has a fixed base plate 58b and a mirror block 70 having a mirror surface on the movable mold 32 side. The mirror block 70 accommodates a heater and a cooling pipe constituting the temperature controller 42b. A groove 62b is provided.

  Further, the pedestal 40a of the movable mold 32 serves as a punching means for punching the sheet-like substrate member 80 into a predetermined shape together with the base member 90. The inner periphery for punching the central hole 15 in the second substrate 21 provided at the center of the pedestal 40a. The punch 64 and a ring-shaped outer peripheral punch 66 provided in the peripheral portion of the base 40 a and punching the sheet-like substrate member 80 into the shape of the second substrate 21 are provided. The pedestal 40b of the fixed mold 34 is provided as a punching means for punching out the sheet-like substrate member 80, and is provided at the center of the pedestal 40b and an inner peripheral die 74 for receiving the inner peripheral punch 64, and at the periphery of the pedestal 40b. It has a ring-shaped outer peripheral die 76 for receiving the outer peripheral punch 66.

  Further, a retainer 67 is provided around the inner peripheral punch 64 of the pedestal 40a so that the stamper 26 can be held on the surface of the stamper block 60. And between the base 40a and the base 40b, it inserts so that the sheet-like board | substrate member 80 may be located in the stamper 26 side, and the base | substrate member 90 may be located in the mirror surface block 70 side. The stamper 26 may be installed on the fixed mold 34 side, but the sheet-like substrate member 80 is also positioned on the stamper 26 side at this time.

  Next, the operation of the stamper press machine 30 will be described. First, the sheet-like substrate member 80, the base member 90, and the stamper 26 are installed at predetermined positions. Next, the temperature of the bases 40a and 40b is measured by the temperature sensors 44a and 44b, and the stamper block 60, the mirror surface block 70, the sheet-like substrate member 80, and the base member 90 are measured by the feedback circuits 46a and 46b and the temperature adjusters 42a and 42b. The stamper 26 is heated and held at a predetermined transfer temperature or a temperature in the vicinity thereof. The temperature on the stamper 26 side and the mirror surface block 70 side does not necessarily have to be the same. By setting the temperature on the mirror surface block 70 side to be slightly lower than that on the stamper 26 side, the sheet-like substrate member 80 is not wrinkled. Further suppression can be achieved.

  Next, the pressure cylinder 36 is driven. When the pressure cylinder 36 is driven, the movable die 32 moves in the direction of the fixed die 34, and the mother die 22a of the stamper 26 is placed on the sheet-like substrate member 80 by the pressure cylinder 36 as shown in FIG. The pressure is pressed. This pressed state is maintained for a predetermined time, whereby the concave / convex pattern 22 is formed on one surface of the sheet-like substrate member 80, and the base member 90 is in close contact with the other surface of the sheet-like substrate member 80. At this time, the inner peripheral punch 64 and the outer peripheral punch 66 of the pedestal 40a protrude toward the pedestal 40b, and the inner peripheral die 74 and the outer peripheral die 76 of the pedestal 40b retreat accordingly. As a result, the sheet-like substrate member 80 is punched into the shape of the second substrate 21 together with the base member 90.

In addition, each speed | rate and time of temperature rising, heat retention, and cooling of each member are preset so that the transferability of the uneven | corrugated pattern 22, the curvature of the sheet-like board | substrate member 80, peelability, etc. satisfy | fill predetermined specifications. The pressing pressure of the stamper 26 is set in advance so that the groove depth of the uneven pattern 22 formed on the second substrate 21 is 80% or more of the groove depth of the master die 22a of the stamper 26. Furthermore, since the accuracy of attaching the inner peripheral punch 64, the outer peripheral punch 66, the inner peripheral die 74, and the outer peripheral die 76 to the stamper 26 is extremely high, the center of the punched second substrate 21 and the approximate center of the concave / convex pattern 22 are aligned. Then, the uneven pattern 22 with less eccentricity can be formed on the second substrate 21. Then, the second substrate 21 is removed from the stamper press 30 together with the base member 90, and the second functional layer 23 is not formed. If the second functional layer 23 has been formed, the process proceeds to the bonding process.

  First, an outer diameter of 138 mm, an inner diameter of 22 mm, and a thickness in which a pit row of the BD-ROM format having a track pitch of 0.32 μm and a mark length of 0.149 μm to 0.596 μm is formed on one surface side. A nickel stamper 26 of 295 μm is installed on the stamper block 60 of the stamper press machine 30. At this time, the mother die 22a formed on the stamper 26 is positioned on the fixed die 34 side.

  Next, a sheet-like substrate member 80 made of polycarbonate having a thickness of 95 μm, a width of 200 mm, and a length of 180 mm (Pure Ace glass transition point = 162 ° C., hardness Shore D = 80, manufactured by Teijin Chemicals Ltd.), and a polyethylene having a thickness of 75 μm The base member 90 (melting point = 80 ° C., hardness shore D = 60) is placed at a predetermined position between the stamper 26 and the mirror block 70. At this time, the sheet-like substrate member 80 is placed on the stamper 26 side.

  Next, the temperature controller 42 a is controlled to heat and hold the stamper block 60 and the stamper 26 on the movable mold 32 side at 130 ° C. Further, the mirror controller 70 on the fixed mold 34 side, the base member 90, and the sheet-like substrate member 80 are heated and held at 120 ° C. by controlling the temperature controller 42b.

  Next, the pressure cylinder 36 is driven to press the stamper 26 against the sheet-like substrate member 80 with a force of 35 kN (kilonewtons) for 1 second. As a result, the master 22 a of the stamper 26 is transferred to one surface of the sheet-like substrate member 80 to form the uneven pattern 22, and the base member 90 is in close contact with the other surface of the sheet-like substrate member 80. At this time, the sheet-like substrate member 80 is punched together with the base member 90 into a disk shape having a diameter of 120 mm having a center hole 15 having a diameter of 15 mm by the punching means of the stamper press machine 30, thereby forming the second substrate 21.

  Next, after cooling the second substrate 21, the base member 90 is removed from the stamper press 30. Next, as a second functional layer 23 on the concavo-convex pattern 22 of the second substrate 21, a semi-transparent silicon hydride film is formed by reactive sputtering using a mixed gas of Si target, argon and hydrogen. A film is formed by an apparatus. As a result, the second information surface 24 including the concave / convex pattern 22 and the second functional layer 23 is formed on the second substrate 21.

  Separately, a nickel stamper having a concave / convex pattern 12 matrix formed on one side is attached to an injection molding machine, and is made of polycarbonate having a concave / convex pattern 12 of 120 mm in diameter and 1.1 mm in thickness by an injection molding method. The first substrate 11 is produced. Next, a 50 nm Ag-Ni-Cu alloy reflective film is formed as a first functional layer 13 on the concave-convex pattern 12 of the first substrate 11 by sputtering. Thereby, the first information surface 14 is formed on the first substrate 11.

  Next, the center hole 15 of the first substrate 11 is inserted into the spindle pin of the spin coater so that the first information surface 14 faces upward. Next, an ultraviolet curable resin is dropped onto the inner peripheral portion of the first substrate 11 while rotating the spin coater at a low speed of 100 rpm. Next, the center hole 15 of the second substrate 21 is dropped into the spindle pin of the spin coater so that the second information surface 24 faces downward. Next, after the first substrate 11 and the second substrate 21 are rotated at a high speed of 1000 rpm, the ultraviolet curable resin is cured by irradiating ultraviolet rays from the second substrate 21 side. Thereby, the cured ultraviolet curable resin becomes the adhesive layer 16 and the first substrate 11 and the second substrate 21 are bonded. Finally, the base member 90 that is in close contact with the second substrate 21 is peeled off by vacuum suction, thereby producing an optical disc D having two layers of information surfaces.

  The optical disk D produced by the above procedure is installed in a reproduction apparatus, the numerical aperture (NA) of the objective lens is 0.85, the reproduction laser beam wavelength is 405 nm, the rotation speed of the optical disk D is 4.9 m / s (linear velocity), Reproduction was performed under conditions of a reproduction laser beam power of 0.35 mW. Note that the incident surface of the laser beam with respect to the optical disc D was on the second substrate 21 side.

  As a result, the eccentricity of the first information surface 14 of the optical disc D was 40 μm, and the eccentricity of the second information surface 24 was 48 μm, both of which were good values within the standard 50 μm. Moreover, the jitter (fluctuation with respect to the time axis of the signal) of the first information surface 14 is 5.5%, and the jitter of the second information surface 24 is 6.2%, both of which are within the standard 6.5%. I took the value. Furthermore, the reflectance of the first information surface 14 was 28%, the reflectance of the second information surface 24 was 26%, and the reflectance of both information surfaces was equal and stable reproduction could be performed.

  From the above, according to the above-described optical disk manufacturing method, it is possible to form the concavo-convex pattern on the sheet-like substrate member 80 by providing the base member 90 at a temperature lower than the glass transition point. Generation of deformation, distortion, and wrinkles on the member 80 and the concavo-convex pattern 22 can be prevented.

  Further, since the heating temperature of the sheet-like substrate member 80 is a relatively low temperature lower than the glass transition point, the cooling time is short and the production efficiency can be improved.

  Further, since the sheet-like substrate member 80 is punched when the uneven pattern is transferred to the sheet-like substrate member 80, the center position of the thin-layer substrate can be matched with the substantially center position of the uneven pattern. A thin layer substrate B having an uneven pattern with few cores can be produced.

  In addition, since the information surface of the thin layer substrate B manufactured by the above-described optical disc manufacturing method is the laser light incident surface, a reproduction signal with good quality can be obtained.

  In this example, the optical disk D having two layers of information has been described as an example. However, the optical disk manufacturing method according to the present invention is performed on a flat disk substrate A as shown in FIG. The thin layer substrate B on which the information surface is formed may be bonded to the optical disk D2 having a single layer information surface, or a flat disk substrate A as shown in FIG. The thin layer substrates B1 and B2 on which the information surface is formed may be bonded together to apply to the production of the optical disc D3 having the two layers of information surface. When forming the optical disk D3, the disk substrate A and the thin layer substrate B1 were bonded together, then the base member 90 of the thin layer substrate B1 was peeled off, and the thin layer substrate B2 was bonded thereon. Thereafter, the base member 90 of the thin layer substrate B2 may be peeled off. In this optical disc D3, since the laser light is also incident on the information surface on the back side from the substrate side, it is possible to obtain a reproduction signal with good quality from both information surfaces. Furthermore, the manufacturing method of the optical disk according to the present invention can be applied to the manufacturing method of the optical disk D4 having an information surface of two or more layers as shown in FIG. 8C, and the present invention is the gist of the present invention. It is possible to change and implement within a range that does not deviate from.

It is a schematic cross section of an optical disc having two information surfaces. It is a figure explaining one Embodiment of the manufacturing method of the optical disk which concerns on this invention. It is a graph which shows the relationship between the temperature of a sheet-like board | substrate member and a base member, and hardness. It is a figure explaining one Embodiment of the manufacturing method of the optical disk which concerns on this invention. It is a figure explaining one Embodiment of the manufacturing method of the optical disk which concerns on this invention. It is a schematic block diagram of the stamper press suitable for the manufacturing method of the optical disk based on this invention. It is the elements on larger scale of the stamper press suitable for the manufacturing method of the optical disk concerning the present invention. It is a figure which shows the example of the optical disk to which the manufacturing method of the optical disk which concerns on this invention is applied.

Explanation of symbols

11 First substrate (disk substrate)
21 Second substrate (thin layer substrate)
22 Uneven pattern
23 Second functional layer
24 Second information surface
26 Stamper
80 Sheet substrate member
90 Base material
A disk substrate
B Thin layer substrate
D Optical disc

Claims (3)

In the method of manufacturing an optical disc, after forming a concavo-convex pattern on a sheet-like member heated to a predetermined transfer temperature, the optical disc is produced by bonding the sheet-like member and a substrate thicker than the sheet-like member.
The one surface side of the sheet-like member is held by a base member having a hardness lower than the hardness of the sheet-like member at the transfer temperature, and the unevenness serving as a matrix of the uneven pattern is formed on the other surface side of the sheet-like member. A heating step of placing a stamper having a pattern and pressing the uneven pattern against the sheet-like member, and heating the sheet-like member to the transfer temperature;
In the state where the stamper is pressed against the sheet-like member heated to the transfer temperature in the heating step, the sheet-like member and the base member are punched into a predetermined shape, and the uneven pattern is formed on the other surface side of the sheet-like member. Forming an adhesion structure having the predetermined shape in which the sheet-like member and the base member are detachably adhered, and
A film forming step of forming a functional film having a predetermined function on the uneven pattern after the adhesion structure forming step;
After the film formation step, a bonding step of bonding the sheet-like member and the substrate in the adhesion structure;
After the bonding step, a peeling step of peeling the base member from the adhesion structure,
Have
The method for producing an optical disc, wherein the transfer temperature in the heating step is lower than the glass transition temperature of the sheet-like member. In the method of manufacturing an optical disc, after forming a concavo-convex pattern on a sheet-like member heated to a predetermined transfer temperature, the optical disc is produced by bonding the sheet-like member and a substrate thicker than the sheet-like member.
A film forming step of forming a functional film having a predetermined function on one surface side of the sheet-like member;
After the film forming step, one surface side of the sheet-like member is held by a base member having a hardness lower than the hardness of the sheet-like member at the transfer temperature, and the uneven pattern is formed on the other surface side of the sheet-like member. And a heating step of heating the sheet-like member to the transfer temperature by disposing a stamper that has a concave-convex pattern serving as a mother mold and pressing the uneven pattern against the sheet-like member;
In the state where the stamper is pressed through the functional film to the sheet-like member heated to the transfer temperature in the heating step, the sheet-like member and the base member are punched into a predetermined shape, and the sheet-like member Forming an adhesion structure having the predetermined shape in which the sheet-like member and the base member are detachably adhered to each other while forming the uneven pattern covered with the functional film on one surface side When,
After the adhesion structure forming step, a bonding step of bonding the sheet-like member and the substrate in the adhesion structure;
After the bonding step, a peeling step of peeling the base member from the adhesion structure,
Have
The method for producing an optical disc, wherein the transfer temperature in the heating step is lower than the glass transition temperature of the sheet-like member. 3. The method of manufacturing an optical disk according to claim 1, wherein the transfer temperature is a temperature equal to or higher than a glass transition temperature of the base member or a temperature equal to or higher than a melting point of the base member.

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