JP2008159187A - Optical recording medium, stamper for manufacturing optical recording medium and manufacturing method of stamper for manufacturing optical recording medium - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To solve the problem that a boundary between a rugged region to be a data signal region and a mirror region can not be identified by using white light having a long wavelength on a mastering original plate, a stamper and an optical recording medium when high density progresses and groove depth and pit depth are made shallow and thereby alignment is made impossible. <P>SOLUTION: In a stamper for forming an optical recording medium wherein a data recording region including ruggedness and an alignment region including ruggedness are provided, depth or height of the ruggedness recorded in the data recording region and depth or height of an alignment signal recorded in the alignment region are different from each other. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an optical recording medium, an optical recording medium manufacturing stamper, and an optical recording medium manufacturing stamper manufacturing method.

  Compact discs (hereinafter abbreviated as CDs) developed as optical recording media for recording audio signals as digital signals have been used as recording media for digital signals other than audio signals. Media for recording digital signals is demanded to improve recording density due to demands for further improvement in storage capacity for personal computer backup, image recording, etc., and is a digital versatile disc (hereinafter abbreviated as DVD). Was developed.

  However, with higher definition and digitization of televisions, higher density is required, and at present, Blu-ray DISK (registered trademark) (hereinafter abbreviated as BD) and High Definition DVD (hereinafter referred to as HD DVD). (Abbreviated as (registered trademark)).

  In general, the recording density of an optical disk greatly depends on the wavelength λ of the laser beam of the recording / reproducing optical system and the numerical aperture NA of the objective lens. That is, the spatial frequency of the record pits capable of signal reproduction is about 2 NA / λ. For this reason, research on increasing the recording density using a short wavelength technique and a high NA technique has been actively conducted. The recording capacity of the optical recording medium is, for example, 650 nm with a recording / reproducing laser beam wavelength of 780 nm and a lens numerical aperture of 0.45 for a CD, whereas the DVD has a laser beam wavelength of 650 nm and a lens aperture. The number is 0.6 and the capacity is 4.7 GB.

  In order to further expand the capacity of the DVD, BD and HD DVD were developed in which the laser wavelength of the recording / reproducing optical system was shortened to 405 nm. HD DVD uses a lens with a numerical aperture of 0.65, and BD uses a lens with a numerical aperture of 0.85. The recording capacity of the BD using a lens with a large numerical aperture can be increased, and a recording capacity of more than 23 GB is obtained in one layer compared to 15 GB, which is the recording capacity of one layer of HD DVD.

  As the recording mark becomes finer due to the shorter wavelength of the laser light of the recording / reproducing optical system and the higher NA, the track pitch becomes narrower. For example, in BD, the track pitch is narrow from 740 nm to 320 nm of DVD. The track depth also decreases in proportion to the wavelength λ as the wavelength is shortened. In BD, the groove depth is very shallow, 20 nm to 30 nm.

  On the other hand, research is being actively conducted to increase the capacity by stacking a plurality of recording surfaces. For example, in DVD and BD, double recording capacity is realized by laminating two recording surfaces. BD is also developing four-layer media aimed at high integration in the next generation.

  The applicant has proposed a method of manufacturing a multilayer optical recording medium having three or more layers in Japanese Patent Application Laid-Open No. 2006-221767. As shown in FIG. 14 (a), a plurality of sheet-like recording medium sheets 141 each having a recording surface are stacked in a state where they are in close contact with each other, and the inner and outer diameters are punched out at once using a punching device 143. This is a method of forming a multilayer optical recording medium 142 that is a laminate.

  In JP-A-2006-221767, as a method for adhering the recording medium sheet 141, a method of adhering the respective layers by pressing the inner peripheral portion and the outer peripheral portion, or an adhesive for bonding to the sheet in advance is applied. A method has been proposed in which the layers are bonded together. Further, an example in which the inside of the punching machine is in a vacuum state when the recording medium sheet is brought into close contact with a certain degree has been proposed. Further, there is a multilayer optical recording medium 144 shown in FIG.

  The multilayer optical recording medium 144 includes a support substrate on which a signal pattern and a recording layer 16 are formed in advance and punched into a disk shape, and a laminate in which the above-described recording medium sheet 141 is laminated via an adhesive layer. It is to be pasted together.

  When the recording medium sheet 141 is laminated, and when the laminated recording medium sheets and the substrate are laminated, the data signal recorded on each recording surface and the disc center hole are aligned so that there is no eccentricity. There is a need. This alignment is performed by an alignment mark provided outside the area to be punched or at least outside the information recording area of the disc.

In a dual-layer DVD, two substrates with a thickness of 0.6 mm are stacked, and a recording layer is formed on the stacked surface of the stacked substrates. Non-Patent Document 1 discloses two types of manufacturing methods as a general method for manufacturing a DVD having a two-layer structure.
(1) A pattern for forming a first recording layer is formed on a first substrate using a stamper. Thereafter, an intermediate layer for forming the second recording layer is laminated on the first recording layer, and then a pattern for forming the second recording layer is formed on the intermediate layer using a stamper. Thereafter, a cover substrate is laminated via an adhesive layer.
(2) A pattern for forming the first recording layer is formed on the first substrate using a stamper. Similarly, a pattern for forming the second recording layer is formed on the second substrate using a stamper. Thereafter, the first substrate and the second substrate are arranged and bonded so that the recording layers face each other.

  In any of the manufacturing methods, the second recording layer is transferred onto the intermediate layer using a stamper. When the recording layer is transferred using a stamper, the substrate having the 0th recording surface and the substrate having the 1st recording surface are aligned using the center pin as a guide with respect to the position of the substrate center hole. It was. Further, the amount of eccentricity between the data signal recorded on the recording surface on the substrate and the central hole depends on the amount of eccentricity between the data signal on the stamper for manufacturing the substrate and the central hole.

  In the case of a DVD, the punching of the center hole when producing a stamper is performed by optically observing the boundary between a data recording area including irregularities consisting of pits or lands and grooves and a flat mirror area without irregularities using a microscope or CCD. However, the eccentricity was adjusted.

  Hereinafter, the reason why the boundary between the data recording area including unevenness and the flat mirror area without unevenness can be optically observed will be briefly described. When the data signal area (irregularity area) is irradiated with light, the reflected light from the bottom of the pit or groove interferes with the reflected light from the part other than the pit or groove, so that the mirror area (area without any irregularity) ), The reflectivity is lower than when light is irradiated. In general, the condition that the reflectance is reduced by interference is expressed by 2nd = λ (2m + 1) / 2 (n = refractive index of optical path, d = depth of groove or pit, m = 0, 1, 2,...・). The boundary between the data recording area and the mirror area is identified by the difference in reflectance.

  As described above, in the optical recording medium, the wavelength of laser light used for recording / reproduction is shortened in order to increase the recording density. With the shortening of the wavelength λ of the reproduction light, the depth d of the pit or groove generally becomes shallower in proportion to λ.

  This depth is determined so that a sufficient amplitude of the tracking signal can be obtained as a groove used as a tracking guide groove at the time of recording / reproducing of a recordable / rewritable optical disk. In the case of a “push-pull signal” that is a typical “tracking signal”, the maximum amplitude is obtained when the groove depth is d = λ / 8n, which is also proportional to the wavelength λ.

  Substituting 1.5 for the wavelength of the blue laser used in BD and HD DVD, λ = 405 nm, and the refractive index n of a plastic member such as polycarbonate, the depth of the groove is about 34 nm, and the groove of the DVD of wavelength 650 nm Compared to the depth of 54 nm, the depth is shallower in proportion to the wavelength.

Also, since the influence of the groove shape on the recording signal characteristics is very large, the depth is generally determined by optimization within a range in which a required amount of tracking signal can be obtained. Therefore, for example, in a phase change type disk using a blue light source of λ = 405 nm, the groove depth is d = 20 to 25 nm, which is further shallower than the above-mentioned λ / 8n (d = 34 nm).
JP 2006-221767 A JP 2003-296976 A “DVD / CD media (RICHO), media technical information (DVD + RW / + R)” [online], [searched on July 4, 2005], Internet <URL: http: // www. ricoh. co. jp / media / techinfo / dvd / index. html>

  When the groove depth is reduced to about 20 nm to 30 nm, the difference in reflectance between the data recording area including unevenness and the flat mirror area without unevenness is reduced in white light. The boundary cannot be identified. That is, the boundary between the data recording area and the mirror area cannot be identified on the recording medium, the recording medium manufacturing stamper, or the mastering master. For this reason, there is a case where the eccentric alignment cannot be performed at the time of punching the center hole of the stamper.

  Also, when laminating sheet-like recording medium sheets, as in the conventional DVD example, if the center pin is aligned with the center hole as a reference, the center hole of the sheet is distorted, The center pin collides with the sheet and damages the sheet, making it difficult to align the center. Again, it is desirable to perform alignment based on the boundary between the data recording area and the mirror area. However, for the above reason, the boundary cannot be identified with white light. There was a case that I could not do.

  For this reason, Japanese Patent Application Laid-Open No. 2003-296976 discloses that a signal part and a marker part on the outer periphery thereof are provided on a stamper. The signal portion is formed with an uneven shape for a signal portion having a depth of 30 nm or less, and the marker portion is formed with an uneven shape for a marker portion having a track pitch of 0.4 to 1.6 μm. Position alignment is performed by the concave / convex shape for the marker portion having a track pitch of 0.4 to 1.6 μm.

  However, sufficient visualization cannot be expected with the pitch alone, and alignment is particularly difficult when stacking sheet-like recording medium sheets.

  The present invention has been made in view of the above-described conventional problems, and an object of the present invention is to provide an optical recording medium manufacturing stamper, an optical recording medium manufacturing stamper manufacturing method, and an optical recording medium that can be easily aligned. It is to provide.

  In order to solve the above-described problems, the present invention provides an optical recording medium having two or more recording layers, the optical recording medium being either a data recording area and at least an inner periphery or an outer periphery of the data recording area. One of them has an alignment region for aligning the positions of the two or more recording layers, and the depth of the alignment pattern formed in the alignment region is deeper than the depth of the signal pattern formed in the data region. An optical recording medium is characterized.

  And a stamper manufacturing method for forming an optical recording medium provided with a data recording area including irregularities on a recording surface and an alignment area including irregular alignment marks for alignment. The method for manufacturing a stamper for manufacturing an optical recording medium is characterized in that the depth of the unevenness differs from the depth of the unevenness included in the alignment region, and the depth of the unevenness can be changed according to the light irradiation conditions for exposure. The resist material is used as a resist, and the resist data recording area and the alignment area are subjected to exposure by changing the light intensity for exposure and / or the speed of light for exposure, followed by development, and further using a material such as nickel. A stamper manufacturing method for manufacturing an optical recording medium, wherein casting is performed and then peeling is performed.

  According to the present invention, alignment with a small amount of eccentricity can be easily performed with white light.

  Next, an embodiment of the present invention will be described.

  FIG. 1 is a schematic configuration diagram of an optical recording medium substrate having a recording surface according to the present invention.

  1A is a plan view of the optical recording medium substrate of the present invention as viewed from above, and FIG. 1B is a schematic cross-sectional view of the optical recording medium of FIG. 1A taken along line AB. .

  The optical recording medium is provided with a data recording area 11 and an alignment mark area 12 on the inner periphery of the data recording area. In the present embodiment, an example in which the alignment mark area is provided in the inner peripheral part of the data recording area will be described. However, the alignment mark area may be provided in the outer peripheral part or in both the inner peripheral part and the outer peripheral part.

  In the data recording area 11, concavities and convexities 13 formed of pits or continuous grooves are formed concentrically or spirally. On the other hand, the alignment mark region is formed with an alignment 14 formed of pits or continuous grooves having a depth at which a reflectance that can be easily identified with white light is obtained, for example, a depth of 35 nm or more.

  Next, a stamper manufacturing method for manufacturing the optical recording medium substrate will be described.

  FIG. 2 is a schematic diagram for explaining a method of creating a mastering master according to the present invention.

  As shown in FIG. 2A, a resist 22 is formed on a glass master 21 to form a resist master. A material whose properties are changed by light irradiation for exposure and whose depth of unevenness can be changed depending on the light irradiation conditions for exposure and development conditions is used as a resist. As the resist, a photon mode resist whose properties are changed by exposure to light or a heat mode resist whose properties are changed by heat may be used.

  As the photon mode resist, for example, a novolak type i-line resist, a polyrose hydroxystyrene type resist for KrF, or an acrylic type ArF resist can be used.

  As the heat mode resist, it is preferable to use a material whose properties are changed by the heat of light for exposure and whose volume and film quality are changed depending on exposure conditions.

  As the material whose volume changes depending on the exposure conditions, the details will be described later, but a material mainly composed of a chalcogen element such as Te other than oxygen and oxygen, or an inorganic material containing an incomplete oxide of a transition metal is used as a resist. Available. Here, the incomplete oxide means a compound shifted in a direction in which the oxygen content is smaller than the stoichiometric composition corresponding to the valence that the transition metal can take.

  In the present embodiment, a negative heat mode resist will be described as an example.

  Next, as shown in FIG. 2B, the exposure light 23 is condensed on the resist 22 and the exposure light (exposure light source) passes through the center of rotation of the resist master while rotating the resist master. By moving on a straight line, a spiral exposure pattern is formed on the resist. Here, different exposure conditions are used for the data recording area and the alignment mark area. The exposure conditions are, for example, the linear velocity and exposure power during exposure. For example, as shown in FIG. 2C, exposure conditions are set such that the volume change amount of the alignment mark area is larger than that of the data recording area.

  In this embodiment, the exposure light source is moved on a straight line passing through the rotation center of the master, and the master is rotated to irradiate the resist with light from the exposure light source. In this case, the amount of light irradiated to a unit area on the master (hereinafter referred to as exposure) is proportional to the light intensity of the exposure light source (hereinafter also referred to as exposure power), and the master rotates. Inversely proportional to the linear velocity due to.

  The method of making the exposure amount of the alignment mark area larger than the exposure amount of the data recording area is roughly divided into the following two methods. The first method is a method of making the exposure power the same and lowering the linear velocity than the exposure condition of the data recording area. The second method is to increase the exposure power by making the linear velocity the same as the exposure condition in the data recording area. The first method and the second method can be combined.

  Note that the method of reducing the exposure amount can be achieved by reversing the above-described conditions.

  In the case of a photon mode type resist, in order to make the depth of the unevenness of the alignment pattern deeper than the depth of the unevenness of the signal pattern, the exposure amount when forming the alignment pattern is set to the exposure amount when forming the signal pattern. This can be achieved by increasing the amount.

  The detailed principle of the WO-type resist, which is a heat mode resist, is unknown, but the volume tends to change according to the change of the linear velocity under the condition of constant exposure power. Therefore, in the case of a negative-type WO resist, it is possible to adjust the groove depth by using this tendency to cause a volume change.

  An exposure pattern having a height d ′ (d) is formed in the data recording area, and a convex exposure pattern having a height d ′ (am) is formed in the alignment area. In order to form an alignment mark having no eccentricity with respect to the recording area, it is necessary to continuously form the recording area and the alignment area using the same exposure light source.

  Here, “continuous” means that the recording area and the alignment area are continuously formed without removing the resist master from the exposure apparatus. The linear velocity is determined by the rotation speed of the glass master, and the exposure power can be changed by changing the intensity of the laser beam by electric means.

  When an inorganic material containing an incomplete oxide of a transition metal is used for the resist 22, the exposed area and the unexposed area have different etching rates. Etching can be performed using an alkali or acid-based etching material.

  Next, as shown in FIG. 2D, the resist in the unexposed area is developed under the condition that the groove depth in the data recording area becomes a desired depth d (d) while leaving the resist in the exposed area. (Etch away). At this time, the alignment mark is exposed under the condition that a desired groove depth (a depth that can be identified with white light) d (am) is obtained after the above development. The master obtained here is referred to as a mastering master 25.

  Although an example using a negative resist has been described, it can be similarly manufactured using a positive resist.

  Next, a stamper is produced from the mastering master.

  FIG. 3 is a schematic view for explaining a stamper manufacturing method according to the present invention.

  As shown in FIG. 3 (a), the mastering master 31 according to the present invention is electroformed with a material such as nickel and then peeled to form a stamper 32 for producing an optical recording medium substrate. On the surface of the above-described stamper 32, a concavo-convex shape is formed in which the concavo-convex shape is reversed from the mastering master. Here, in consideration of the polarity of the concavo-convex shape finally produced on the optical recording medium, an inversion step by a glass 2P (Photo Polymer) method or the like may be included.

  The stamper according to the present invention is formed with an alignment mark composed of pits or continuous grooves at a depth at which a reflectance that can be easily identified with white light is obtained. A small amount of alignment is possible. The center hole can be formed using a punching machine. FIG. 3B.

  The optical recording medium substrate shown in FIG. 1 can be manufactured by performing, for example, injection molding using the stamper thus manufactured.

  Here, the alignment mark will be described. A case where a plurality of optical recording medium substrates and optical recording medium sheets having a recording surface on one surface are stacked will be described. Each of the optical recording medium substrate and the optical recording medium sheet having one recording surface is referred to as a “layer”.

  FIG. 4 is a conceptual diagram illustrating an example of an alignment mark according to the present invention.

  For example, alignment marks AM1, AM2, and AM3 having different radii such as r1, r2, r3,... Are formed on the first layer 41, the second layer 42, the third layer 43,. Further, for example, the reference alignment marks AMB1, AMB2, and AMB3 corresponding to the alignment marks are formed on the B-layer 40 serving as at least one reference. This reference alignment mark may be formed in any layer.

  The alignment mark may be formed outside the data recording area, and may be formed at a radius that is finally transferred to the disk, or a radius that is not transferred to the disk (for example, a radius smaller than the center hole of the disk, or the disk May be formed with a radius larger than the outer diameter. Further, it may be an intermittent shape instead of a continuous linear shape.

FIG. 5 is a schematic view showing an example of a method for producing an optical recording medium sheet according to the present invention.
The stamper for producing the optical recording medium sheet can be produced by the same method as the stamper for producing the optical recording medium substrate described above.

  As shown in FIG. 5A, for example, a stamper is applied to a material capable of transferring an uneven shape, such as a thermosetting resin or an ultraviolet curable resin, or a material capable of transferring an uneven shape by pressure. The optical recording medium sheet 53 is formed by pressing 51 to transfer the uneven shape onto the surface. Next, as shown in FIG. 5C, a recording layer or a reflective layer 54 is formed on the surface on which the concavo-convex shape is formed, for example, by sputtering. If necessary, a dielectric layer, a recording layer, a semi-transmissive reflective layer, and a reflective layer are formed.

  Here, in the case where the recording layer or the reflective layer makes it impossible to detect the alignment mark when the layers are laminated, the recording layer or the reflective layer may be configured not to be formed in the alignment region. Further, in the case where the alignment mark is identified better by forming the recording layer or the reflective layer, the recording layer or the reflective layer may be formed in the alignment region.

  In the optical recording medium according to the present invention, since the alignment irregularities made of pits or continuous grooves are formed at a depth at which a reflectance that can be easily identified with white light is obtained, the optical recording formed in a sheet shape. When a plurality of media sheets are stacked, alignment with a small amount of eccentricity can be performed using a microscope.

(Example 1)
Hereinafter, although the detailed Example of the optical recording medium according to this invention is described, it is not a thing limited to this structure.

  In this embodiment, a substrate having a recording surface on at least one surface and a structure in which sheets are stacked are taken as an example. Specifically, the substrate is the 0th layer, the first layer, the second layer, and the third layer are An optical recording medium having a four-layer structure in which sheets are laminated will be described as an example.

A negative type tungsten oxide WO _1-x having a composition in which oxygen is deficient in a trace amount from a stoichiometric composition will be described as an example of the resist. Tungsten oxide WO _1-x in which a small amount of oxygen is lost from the stoichiometric composition changes the state of the layer by irradiating light for exposure, the volume increases, and the exposed portion becomes convex. Furthermore, the volume change amount can be adjusted by the moving speed and intensity of the exposure light.

Tungsten oxide WO _1-x in which a small amount of oxygen is lost from the stoichiometric composition can be formed by sputtering. Sputtering in an atmosphere of inert gas (excluding nitrogen) using tungsten as a target and sputtering in an oxygen atmosphere and tungsten oxide WO _{1-x in} which a small amount of oxygen is lost from the stoichiometric composition as a target Also good.

The negative type tungsten oxide WO _1-x is alkali-soluble in the sputtered state. Alkali insolubility can be achieved by changing the state of the layer by exposure. For resist design, select the optimal composition and layer thickness in consideration of optical characteristics for exposure light, volume variation with respect to exposure light, etching characteristics with respect to solvent for development, groove shape to be formed, etc. Can do. In this example, tungsten oxide having a layer thickness of 100 nm was formed.

  The case where the inside of the recording area is used as the alignment mark area and the concentric circle shape is used as the alignment mark shape will be described as an example.

  FIG. 6 is a schematic diagram for explaining a method for producing a mastering master for producing an optical recording medium according to the first embodiment.

As shown in FIG. 6 (a), tungsten oxide in which a small amount of oxygen was lost from the stoichiometric composition was formed on a quartz master 61 to obtain a resist master. Tungsten oxide deficient in oxygen from a stoichiometric composition was formed by sputtering a target containing W in an atmosphere of Ar gas and O ₂ gas.

The amount of oxygen in tungsten oxide can be adjusted by changing the ratio of Ar gas to O ₂ gas. The layer thickness can be adjusted by the sputtering time. In Example 1, the layer thickness was 100 nm, and the composition had an absorptivity of 30% with respect to the wavelength of 351 nm as exposure light.

  The resist made of the metal oxide can form a film having an absorptance of about 30% at a wavelength of 351 nm depending on the composition. Therefore, a substrate having a high ultraviolet region transmittance such as a synthetic quartz substrate is used as a resist master. Can be used as a transparent stamper instead of a transparent stamper using a resin. In this case, since it is not necessary to use a disposable stamper made of resin, production efficiency can be improved.

  Next, exposure is performed. As shown in FIG. 6B, the exposure light 63 is condensed on the resist from the exposure source, and the exposure source is moved in the radial direction 64 of the disk while rotating the resist master, so that the resist is moved onto the resist. A convex spiral exposure pattern was formed.

  In this embodiment, the wavelength of the exposure light 63 is 351 nm. The exposure conditions for the data recording area were a linear velocity of 0.7 m / s and a power of 1.4 mW, and the exposure conditions for the alignment mark area were a linear speed of 2 m / s and a power of 1.4 mW. Both track pitches TP were 320 nm.

  As a result, as shown in FIG. 6C, a convex exposure pattern having a width of 150 nm and a height d ′ (d) = 5 nm is formed in the data recording area, and the alignment area has a width of 120 nm and a high height. A convex exposure pattern of d ′ (am) = 30 nm was formed. Here, the volume change of 13 resists will be briefly considered. The resist heating time, the temperature gradient to be heated, and the cooling state change depending on the linear velocity at the time of exposure. As a result, it is considered that the crystal state of the resist changes and the volume changes.

  Next, development is performed. As shown in FIG. 6D, unexposed resist is removed using an alkali developer (TMAH (tetramethylammonium hydroxide: 0.5%)), and the groove depth of the data recording area is removed. Is developed so that the length of the groove in the alignment mark region is d (am) = 35 nm.

  As the alkaline developer, KOH, NaOH, or the like can be used.

  Next, the alignment mark will be described. In Example 1, as shown in FIG. 7A, the alignment mark area is provided on the inner peripheral side of the data recording area. As the shape, an alignment mark as shown in FIG. 8 was used. Alignment marks AM1, AM2, and AM3 were formed on the first layer, the second layer, and the third layer, respectively. On the 0th layer, alignment marks AM01, AM02, AM03 corresponding to the alignment marks AM1, AM2, AM3 were formed.

  The alignment mark is a concentric circle as a whole image, but includes a plurality of spiral tracks as shown in the enlarged view of FIG. The alignment marks AM1, AM2, and AM3 have different radii so that they do not overlap each other. The corresponding alignment marks have different radii so that AM1 and AM01, AM2 and AM02, and AM3 and AM03 do not overlap.

  In this embodiment, the alignment marks AM1, AM2, and AM3 were formed at positions having radii of 20.75 mm to 20.85 mm, 20.45 mm to 20.55 mm, and 20.15 mm to 20.25 mm, respectively.

  An aggregate of grooves formed at a pitch of 0.32 μm in an alignment region having a width of 0.1 mm can be considered as a circle. The width of the alignment mark only needs to be observable with a microscope used for observation, and preferably 5 μm or more can be selected.

  Corresponding alignment marks AM01, AM02 and AM03 were formed to have a radius of 20.6 mm to 20.7 mm, 20.3 mm to 20.4 mm, and 20 mm to 20.1 mm.

  The alignment mark of Example 1 is concentric (spiral) and formed continuously with the data signal, so there is almost no eccentricity.

  Although the above description has been made using a spiral, the same effect can be obtained by forming concentric circles instead of the spiral.

  A mastering master for the 0th layer, a mastering master for the first layer, a mastering master for the second layer, and a mastering master for the third layer, each having the alignment marks described above, were prepared.

  Next, as shown in FIG. 7B, Ni electroforming is performed on each mastering master, and the 0th layer forming stamper, the 1st layer forming stamper, the 2nd layer forming stamper, and the 3rd layer forming stamper. Was made.

  Next, as shown in FIG. 9A, a center hole 91 was formed by punching in the central portion of the stamper 94 for forming the 0th layer. The center hole was formed using a punching machine, for example, by observing the alignment mark AM03 with a microscope and adjusting the position of the eccentric alignment, thereby forming the center hole with a small amount of eccentricity. Since the alignment mark of the present invention is provided with irregularities having a groove depth of 35 nm, the alignment mark can be identified with a microscope.

  Next, as shown in FIG. 9B, a zeroth-layer optical recording medium substrate was formed. In Example 1, the 0th layer forming stamper was set in an injection mold, and the 0th layer optical recording medium substrate was molded using a polycarbonate resin having a thickness of 1.1 mm.

  As a result, the 0th layer optical recording medium substrate 93 was formed on the surface of the substrate in which the concave and convex portions of the data recording area and the alignment mark area and the central hole having almost no eccentricity were formed.

  Next, first layer, second layer, and third layer optical recording medium sheets were prepared using a first layer forming stamper, a second layer forming stamper, and a third layer forming stamper.

  FIG. 10 is a schematic diagram showing an example of a method for producing an optical recording medium according to the present invention. As the sheet thickness, sheet thicknesses of 12 μm, 13 μm, and 14 μm were used. By changing the thickness of the sheet of each layer, it was possible to change the interlayer distance without changing the thickness of the adhesive, and to suppress the signal interference of each layer. A thermoplastic resin can be used as a material for the sheet. In this embodiment, a polycarbonate resin sheet base material was used.

  As shown in FIG. 10A, the stamper 101 was pressed against the sheet 103 while being heated to a temperature higher than the heat distortion temperature of the polycarbonate resin by the heater 102, thereby transferring the irregularities on the stamper to the sheet surface. Next, after the stamper was cooled, the stamper and the sheet were peeled off. Thereby, the optical recording medium sheet 104 of each layer in which the unevenness of the data recording area and the alignment mark area was formed on the surface of the sheet 103 was formed. Here, the heat distortion temperature of the polycarbonate resin was 120 ° C. The material of the sheet and the material of the substrate are not particularly limited as long as they are materials that do not optically interfere with recording, reproduction, and erasing.

  A recording layer is formed on each optical recording medium manufactured as described above. As the configuration of the recording layer, for example, a dielectric layer, a recording layer, a dielectric layer, a reflective layer, or a reflective layer is formed. In the first embodiment, as shown in FIG. 11, a recording layer is formed in the alignment region by covering portions other than the data recording region (the alignment portion on the inner periphery of the substrate and the outer periphery of the substrate) with a mask. The configuration was not.

  As an optical recording film material, at least one kind of materials such as Te, In, Ga, Sb, Se, Pb, Ag, Au, As, Co, Ni, Mo, W, Pd, Ti, Bi, Zn, and Si are used. Alloys made of and the like are widely known. Many of these materials already exist as known techniques.

  In addition, alloys made of at least one of Tb, Fe, Co, Cr, Gd, Dy, Nd, Sm, Ce, Ho, and other rare earth-transition metal alloys are often used as magneto-optical recording materials. Many of these materials already exist as known techniques.

  Al, Al alloy, Si, SiN, Ag, Ag alloy, and the like are also used as the reflective film material, and many materials already exist as known techniques.

  Furthermore, organic dye-based materials such as cyanine-based, phthalocyanine-based, and azo-based materials can be used as the recording layer.

The film thickness of the recording layer or the reflective layer can be arbitrarily set, but since the light attenuation occurs in each recording layer and the reflective layer from the light incident surface side, the transmittance at the wavelength of the light used is closer to the incident surface side. It is desirable to increase. Further, it is preferable to adjust the composition and film thickness of each recording layer and the reflective layer so as not to hinder the recording / reproducing / erasing of each layer.
As the film forming method, a sputtering method, a vapor deposition method, a CVD method, a dipping coating, a spin coating coating, and the like can be considered, and any method that is optimal for each production process, production apparatus, and recording medium to be produced is particularly limited. is not.

  By optimizing the composition, film thickness, film forming conditions, and the like for each sheet base material and substrate, a recording layer and a reflective layer having arbitrary transmittance and reflectance can be formed.

  In the present invention, there is no particular limitation by using a recording layer material suitable for the required optical recording medium.

  Next, an optical recording medium of each layer was laminated.

  FIG. 12 is a schematic diagram for explaining the superposition process of the first embodiment.

  The 0th layer 120 includes the optical recording medium substrate and the recording layer described with reference to FIG. 11, and the first layer 121, the second layer 122, and the third layer 123 include the optical recording medium sheet and the recording layer.

  In Example 1, each layer was bonded using a transparent pressure-sensitive adhesive sheet. The pressure-sensitive adhesive sheet may be a material having a high transmittance with respect to the wavelength of the laser beam used for recording / reproduction.

  First, a pressure-sensitive adhesive sheet (not shown) is sandwiched between the 0th layer 120, the first layer 121, the second layer 122, and the third layer 123, and the layers are overlapped with each other being in close contact with each other.

  Regarding the alignment in the direction B perpendicular to the paper surface, the alignment driving device 124 precisely aligned each layer. The alignment in the direction of the arrow A was performed precisely by the roller 126 holding each layer.

  Here, the alignment by the alignment mark will be described. As shown in FIG. 8C, for example, the positions of four locations A, B, C, and D on the circumference are aligned so that the distances between AM01 and AM1 at the four locations are the same. Similarly, the distance between AM02 and AM2 and the distance between AM03 and AM3 were adjusted to be the same.

  In FIG. 8, alignment was performed using a microscope.

  The distance was measured using a scale memory in which 10 mm formed on a 40 × objective lens and a 10 × eyepiece of the microscope were divided into 100 equal parts. When measuring with a scale memory obtained by equally dividing 10 mm formed on a 40 × objective lens and a 10 × eyepiece lens into 100 equal parts, since the size of one scale is 2.50 μm, sufficient alignment can be performed.

  Since the alignment mark of the present embodiment is formed with irregularities with a groove depth of 35 nm, it is easy to identify with white light. Therefore, the alignment mark is recognized through the plurality of layers, and the alignment of the multilayer is performed. Can be done together. Furthermore, since the alignment marks of the respective layers are aligned with respect to the reference alignment marks provided on the reference layer, deviations in eccentricity are not accumulated. Further, since the alignment mark is formed outside the data signal region, it is not necessary to reduce the area of the data region.

  If the depth of the alignment pattern was 35 nm or more, alignment could be performed without any problem using white light.

  After laminating in this manner, the first layer 121, the second layer 122, and the third layer 123 formed in a sheet shape are pressure-bonded by a punching device (not shown) and simultaneously punched. At this time, the inner diameter was collectively punched to a radius larger than that of the 0th layer optical recording medium substrate, and the outer diameter was collectively punched to a radius smaller than that of the 0th layer optical recording medium. However, the punching machine was adjusted so as not to punch the 0th layer optical recording medium substrate. As shown in FIG. 12B, a four-layer optical recording medium was formed. Further, a 75 μm protective sheet 127 having no uneven pattern was laminated on the uppermost layer to complete a four-layer optical recording medium.

  When reproduction evaluation was performed using a laser beam having a wavelength of 405 nm from the protective coating surface side of the completed optical recording medium having a four-layer structure, each layer had a small amount of eccentricity and good reproduction was achieved.

  According to the present embodiment, other layers can be stacked on the 0th layer having a center hole having almost no eccentricity with respect to the data signal in a state where there is almost no eccentricity. Can be adjusted to 20 μm P-P or less.

(Example 2)
In Example 2, a recording layer was formed on the optical recording medium substrate 93 of the 0th layer produced in Example 1, and a 100 μm protective sheet having no concavo-convex pattern was laminated on the uppermost layer to complete the optical recording medium. . When reproduction was evaluated using a laser beam having a wavelength of 405 nm from the protective coating surface side of the completed optical recording medium, each layer had a small amount of eccentricity and good reproduction was possible.

(Example 3)
In example application 3, a photon mode resist that is exposed to light and changes from alkali-insoluble to alkali-soluble is described as an example.

  In the 13-photon mode resist, the amount of exposure of the resist, that is, the changing depth varies depending on the exposure light irradiation amount. Therefore, the depth of the unevenness can be changed depending on the exposure light irradiation condition and the development condition.

  As shown in FIG. 13A, a novolac i-line resist was formed on a quartz master 131 to a thickness of 100 nm.

  Next, exposure is performed. As shown in FIG. 13B, the exposure light 133 is condensed on the resist, the exposure light (exposure light source) is moved in the radial direction 134 of the disk while rotating the resist master, and the resist master is moved. A spiral exposure pattern was formed on the resist. The exposure conditions for the data recording area were a linear speed of 2.0 m / s and a power of 0.2 mW, and the exposure conditions for the alignment mark area were a linear speed of 2 m / s and a power of 0.5 mW. The track pitch TP in the data recording area was 320 nm, and the track pitch TTP in the alignment mark area was 1 μm.

  Next, development is performed. As shown in FIG. 13D, the portion of the resist changed by exposure is removed using an alkali developer TMAH 0.5%, the groove depth of the data recording area is d (d) = 20 nm, and the alignment mark area Development was performed so that the groove depth was d (am) = 100 nm.

  Here, since the groove depth was deep and the track pitch was wide, the alignment mark of Example 3 was better identified with the microscope than the alignment mark of Example 1.

  Except for the above, an optical recording medium was produced in the same steps as in Example 1. When reproduction evaluation was performed in the same manner as in Example 1, the eccentricity of each layer with respect to the center of the center hole could be adjusted to 10 μm P-P or less, and good reproduction was possible.

Example 4
In Example 4, an optical recording medium was manufactured in the same process as in Example 1 except that the track pitch of the alignment mark was 1 μm. Here, the alignment mark of Example 3 was better identified with a microscope than the alignment mark of Example 1. When reproduction evaluation was performed in the same manner as in Example 1, the eccentricity of each layer with respect to the center of the center hole could be adjusted to 15 μm P-P or less, and good reproduction was possible.

1 is a schematic configuration diagram of an optical recording medium substrate having a recording surface according to the present invention. The schematic diagram explaining the preparation method of the mastering original disc by this invention. The schematic diagram explaining the manufacturing method of the stamper by this invention. The conceptual diagram explaining an example of the alignment mark by this invention. The schematic diagram which shows an example of the preparation method of the optical recording medium sheet | seat by this invention. FIG. 3 is a schematic diagram illustrating a method for creating a mastering master for manufacturing an optical recording medium according to Embodiment 1. FIG. 3 is a schematic diagram for explaining an alignment mark region according to Embodiment 1 and a schematic diagram for explaining a stamper manufacturing method. FIG. 3 is a conceptual diagram illustrating alignment marks according to the first embodiment. FIG. 6 is a schematic diagram illustrating a method for manufacturing a 0th layer according to Example 1; FIG. 3 is a schematic diagram illustrating a method for manufacturing a first layer, a second layer, and a third layer according to Example 1. FIG. 3 is a schematic diagram illustrating a film formation region of a recording layer according to Example 1. FIG. 3 is a schematic diagram for explaining an overlay process according to the first embodiment. FIG. 9 is a schematic diagram for explaining a method for creating a mastering master for manufacturing an optical recording medium according to a second embodiment. The schematic diagram for demonstrating a prior art example.

Explanation of symbols

11 Data recording area 12 Alignment mark area 13 Concavity and convexity 14 Concavity and convexity 21 Glass master 21
22 resist 22
23 Light 23 for exposure
25 Mastering master 31 Mastering master 32 Stamper 33 Center hole 40 B layer 41 First layer 42 Second layer 43 Third layer 51 Stamper 53 Optical recording medium sheet 54 Recording film 61 Quartz master disk 62 Resist 63 Light for exposure 91 Center hole 92 Center hole 93 0th layer optical recording medium substrate 94 0th layer forming stamper 101 stamper 102 heater 103 sheet 104 optical recording medium sheet 111 recording film 120 0th layer 121 1st layer 122 2nd layer 123 3rd layer 124 alignment Driving device 125 Optical microscope 126 Roller 127 Protective sheet 131 Quartz master disk 132 Resist 135 Mastering master disk 141 Recording medium sheet 142 Multi-layer optical recording medium 143 Punching machine 144 Multi-layer optical recording medium 145 Support substrate

Claims (16)

An optical recording medium having two or more recording layers,
The optical recording medium has an alignment area for aligning the position of the two or more recording layers with either a data recording area and at least one of an inner periphery and an outer periphery of the data recording area,
An optical recording medium, wherein an alignment pattern formed in the alignment region is deeper than a signal pattern formed in the data region. The optical recording medium is a laminate of a substrate or sheet on which a first information recording layer is formed and a sheet on which at least one surface has a second information recording layer formed,
A first alignment region on either the inner periphery or the outer periphery of the first recording region on which the first information recording layer of the optical recording medium is formed;
2. The optical recording medium according to claim 1, further comprising a second alignment area on either the inner periphery or the outer periphery of the second recording area on which the second information recording layer of the sheet is formed. .   The unevenness depth of the signal pattern formed in the data region is 30 nm or less, and the unevenness depth of the alignment pattern formed in the alignment region is greater than 35 nm. Optical recording medium.   4. The optical recording medium according to claim 1, wherein the alignment pattern is a group of irregularities formed by grooves or patterns that are spirally or concentrically formed. 5.   There are at least two or more sheets, and the alignment patterns formed on the two or more sheets are formed at different positions on each sheet, and at least one of the substrate or the sheet includes the alignment pattern on each sheet. The optical recording medium according to claim 2, wherein an alignment pattern is formed at an opposing position.   6. The optical recording medium according to claim 1, wherein each of the alignment patterns is concentric with different radii. The alignment in which the alignment region is provided with a data recording region in which a signal pattern is formed and a sheet and a substrate having an alignment region in which an alignment pattern is formed at least either on the inner periphery or the outer periphery of the data recording region An optical recording medium manufacturing stamper for manufacturing the substrate or the sheet of optical recording media laminated using a pattern,
A stamper for manufacturing an optical recording medium, wherein an alignment pattern formed in the alignment region is deeper than a signal pattern formed in the data region of the stamper.   The depth of the unevenness of the signal pattern formed in the data region is 30 nm or less, and the depth of the unevenness of the alignment pattern formed in the alignment region is greater than 35 nm. Stamper for manufacturing optical recording media.   8. The optical recording medium manufacturing stamper according to claim 7, wherein a central hole concentric with the alignment mark formed in the alignment region is formed.   8. The optical recording medium manufacturing stamper according to claim 7, wherein the alignment mark formed in the alignment region is spiral or concentric. A method of manufacturing a stamper for forming an optical recording medium provided with a data recording area including unevenness on a recording surface and an alignment area including uneven alignment marks for alignment, the unevenness included in the data recording area And a method of manufacturing a stamper for manufacturing an optical recording medium, wherein the depth of the unevenness included in the alignment region is different,
Using a resist that can change the depth of the unevenness according to the light irradiation conditions for exposure, exposure is performed by changing the light intensity for exposure and / or the speed of light for exposure between the resist data recording area and the alignment area. A method for producing a stamper for producing an optical recording medium, comprising: performing development, then developing, further electroforming with a material such as nickel, and then peeling.   12. The method of manufacturing a stamper for manufacturing an optical recording medium according to claim 11, wherein the resist is a material whose volume change amount varies depending on the intensity or linear velocity of the light irradiation for exposure.   13. The method for manufacturing a stamper for manufacturing an optical recording medium according to claim 12, wherein the resist material is an inorganic material containing an incomplete oxide of a transition metal.   7. The optical recording medium manufacturing stamper according to claim 6, wherein the unevenness included in the data recording area and the unevenness included in the alignment area are continuously exposed using the same exposure light. Production method.   12. The exposure amount of the data recording area and the alignment area is controlled by controlling a linear velocity of the glass master and changing an irradiation amount of light from the exposure light source. A method for producing a stamper for producing an optical recording medium as described in 1 above.   12. The exposure amount of the data recording area and the alignment area is controlled by controlling the irradiation amount of light from the exposure light source to be constant and changing the linear velocity of the glass master. A method for producing a stamper for producing an optical recording medium as described in 1 above.

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