JPH08287525A - Production of optical master disk - Google Patents

Abstract

PURPOSE: To facilitate the production of a stamper by dividing the patterns to be displayed to two; a main subject material and a background, and forming stage groups for discretely forming the background partial patterns and the pattern parts of the main subject material. CONSTITUTION: A substrate for development formed with a photoresist layer 31 on a glass substrate 32 is prepd. A master mask disk 25 is placed as a mask on the photoresist layer 31 and is integrally exposed from above the disk, by which the latent images of the background display patterns are formed as a first exposing stage. A negative film 33 for the main display patterns transferred with the patterns of, for example, characters, symbols, pictures, etc., which are the main subject material is arranged on the photoresist layer 31 formed with the latent images of the background display patterns and the photoresist layer is again integrally exposed, by which the latent images are formed as a second exposing stage. Finally, metallic conductive films are uniformly laminated on the surface of the master disk and resist dummy pit arrays as an electroforming stage.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing an optical disk master, and more particularly to a method for manufacturing an optical disk master for a reflection type optical disk composed of translucent circular substrates bonded to each other.

[0002]

2. Description of the Related Art Generally, in an optical disc, a CD is read by irradiating a laser beam from only one side.
In the single plate disc as described above, the identification display of the recorded content is based on a visible print pattern or label on the protective film on the back side of the recording surface. A digital video disc (hereinafter referred to as a DVD) in which a pair of discs each having an information recording area on a transparent substrate are bonded on the information recording area side,
There is also a laminated double-sided type such as a laser disk (hereinafter referred to as LD). Also on this double-sided type optical disc, a recorded content is displayed with a label and a print pattern.

Further, as to an optical disk manufacturing method in which a label and a print pattern are displayed in an external process, for example, as disclosed in Japanese Patent Publication No. 5-797, a label area and an information recording area around a center hole of the optical disk. There is a method in which a visible character pattern or the like is formed inside the disc in the information non-recording area adjacent to the area. However, since the pattern display area area is small and narrow between such a label area and the information recording area, especially in a small high-density optical disk such as a DVD, it is not possible to display a sufficiently large pattern and the display information amount is limited. Has been done.

Further, as disclosed in Japanese Utility Model Application Laid-Open No. 2-30126, a method of forming a hologram pattern in an information non-recording area adjacent to an information recording area, that is, a display pattern is recorded in advance on an optical disc master, a so-called stamper. There is also a method of forming it together with the region and displaying it in an internal process, but similarly, the display information amount is limited.

On the other hand, in a conventional method of manufacturing a stamper for mass-producing optical disks, a method of forming a predetermined pattern of sequential or scanning exposure and etching on a photoresist layer is used. As a method of manufacturing an optical disk stamper, first, as a laser cutting process, a resist substrate having a positive resist layer uniformly formed on the main surface of a glass substrate is rotated, and a laser beam modulated according to a predetermined signal is used as a substrate. By moving in the radial direction, a latent image of a minute spot array corresponding to predetermined information is formed on the resist layer in a spiral or concentric pattern at a predetermined track pitch, and the sequentially exposed resist substrate is developed, and the resist layer is dried and fixed. (Post-baking) A substrate having recesses corresponding to signals to be recorded is obtained on the resist substrate.
Next, as an electroforming step, a metal is laminated as a conductive film on the resist layer. The base with a conductive film is immersed in an electroforming tank to form a thick metal layer, that is, a stamper on the conductive film. Here, in the case of continuous irradiation of the laser beam, the concave portion becomes a pre-groove, and in the case of intensity modulation which causes blinking, it becomes a pit row.
(Hereinafter, pregrooves and pits are also collectively referred to as pits) Finally, the stamper is separated from the glass substrate, and the resist layer and conductive film remaining on the stamper are removed to obtain the stamper.

An optical disk replica having a predetermined information recording surface is produced by an injection molding device using this stamper. An optical disc is formed by forming a reflective layer on the information recording surface of the obtained replica and further forming a protective film on the reflective layer.

[0007]

Here, in the conventional method for manufacturing an optical disk master, as described in Japanese Patent Publication No. 5-797, the information is recorded on the photoresist layer in the laser cutting process. A display pattern is recorded, and a stamper is created by a developing and electroforming process. When the display pattern is formed in the laser cutting process as described above, there arises a problem that the manufacturing yield of the stamper is lowered. Furthermore, in a small-diameter optical disk such as a DVD, the display area is small, and a sufficient pattern display portion cannot be provided.

Therefore, an object of the present invention is to provide a method of manufacturing an optical disk master having a high yield and capable of displaying a clear and large pattern such as a large character.

[0009]

According to the method of manufacturing an optical disc master according to the present invention, one of the recording surfaces has a recording track formed in a concentric circle shape or a spiral shape consisting of a pit row carrying an information signal, and the recording surface. The other has a diffraction grating area that produces diffracted light by incident light and a display pattern area that is formed in the diffraction grating area and does not produce diffracted light by the incident light.Pit rows are formed on both recording surfaces. A method of manufacturing an optical disk master for a reflective optical disk to be obtained, comprising a translucent substrate, and an opaque thin film formed on the translucent substrate and having an opening for forming the diffraction grating region. A step of forming a mask master, a step of forming a display pattern mask having a light-transmitting portion for forming a display pattern area, and a developing step having a photoresist layer on the main surface. A step of forming a plate, a first exposure step of arranging the mask master on the photoresist layer of the developing substrate, and exposing the photoresist layer collectively through the opening of the opaque thin film; A second exposure step of arranging the display pattern mask on the photoresist layer of the substrate and exposing the photoresist layer collectively through the light transmitting portion; and exposing in the first and second exposure steps. Developing the development substrate having the photoresist layer formed as described above.

Further, in the optical disc master manufacturing method, the order of the first exposure step and the second exposure step is exchanged, or the mask master and the display pattern mask are arranged on the photoresist layer in an overlapping manner. ,
The first exposure step and the second exposure step may be performed simultaneously. Furthermore, in the above optical disc master manufacturing method, it is preferable that the diffraction grating region is a hologram, or a dummy pit row or a pre-groove formed in a spiral shape or a concentric shape at a predetermined pitch, or in a parallel straight line shape at a predetermined pitch. .

[0011]

According to such a method for manufacturing an optical disk master, in the method for manufacturing an optical disk, for example, a mask master having a partial pattern as a background is formed by making the rainbow color display by the reflected and diffracted light from the diffraction grating common and collectively exposing. Since it is composed of a process group and a process group in which the pattern portion of the main subject on the background is individually and collectively exposed, the mask master of the background display pattern can be repeatedly used,
As a master disc family, it is possible to easily duplicate the signal of the background display pattern. Further, unlike the conventional case, it is not necessary to perform laser cutting for each main pattern each time, and a variety of combinations of the background pattern and the main display pattern are provided, so that various stampers can be easily manufactured.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A method of manufacturing an optical disk and an optical disk master according to an embodiment of the present invention will be described below with reference to the accompanying drawings. (Reflective Double-sided Optical Disk) As shown in FIG. 1, the optical disk 42 of the embodiment is a double-sided type optical disk in which the information recording disk portion 12 and the dummy disk portion 11 are joined together via the adhesive layer 5.

The information recording disk section 12 has a circular substrate 8 formed on one side of a plurality of information pits 10 forming a concentric circular or spiral recording track for carrying an information signal, and a substrate 8 thereof. Metal reflective layer 7 formed on the information pit forming surface of the above, and a protective film 6 covering the reflective layer 7.
It consists of and. The dummy disk unit 11 includes a circular substrate 2 having a plurality of pits having no relation to information signals, that is, dummy pits 9 formed as a pit group on one surface,
It is composed of a metal reflection layer 3 formed on the dummy pit formation surface of the substrate 2 and a protective film 4 covering the reflection layer 3. The dummy pit 9 is formed in order to obtain a vivid rainbow color generated by reflected diffracted light.

Two circular substrates 2 and 8 having the same circular size are
A double-sided optical disk 42 made of a transparent synthetic resin or the like and bonded by an adhesive layer 5 between the protective films 4 and 6 formed on one surface of each disk portion.
Are formed. In both disc parts, the pre-pits and dummy pits corresponding to the data to be reproduced are already injection-molded (injection-molded) on the plastic substrate.

The substrate is not limited to an integrally formed injection-molded resin substrate, but a so-called 2P (photo-polymer) is used, in which a fluid ultraviolet curable resin is formed on a transparent substrate as a transfer layer such as a pre-groove. The substrate may be formed by the method). The transparent substrate material in the present invention, acrylic resin such as polymethylmethacrylate (PMMA), polycarbonate (PC), polyvinyl chloride, polyimide, polyamide, cellulose triacetate, in addition to polymeric materials such as polyethylene terephthalate, glass and ceramics And so on.

Examples of the material for the reflective layer in the present invention include metals with high reflectance such as gold (Au), copper (Cu), aluminum (Al), and alloys thereof. For example, a vacuum deposition method, a sputtering method, The reflection layer can be formed by the ion plating method. The protective film in the present invention is formed by spin-coating an ultraviolet curable resin and applying it, and then irradiating it with ultraviolet rays to cure the coating film. In addition, epoxy resin, acrylic resin, silicone resin,
Urethane resin or the like is used as the protective film material. Also,
The protective film may be omitted if the reflective layer has durability.

As the adhesive layer in the present invention, an adhesive such as a hot melt adhesive, an ultraviolet curable resin, a rubber adhesive, a urethane adhesive, an epoxy adhesive, a roll coat method, a spin coat method, It can be used by a screen printing method or the like. In addition, in the present invention, in addition to the ROM type reflection type optical disc in which the information recording disc portion 12 having the information recording area of the above-mentioned embodiment is a prepit and a reflection film,
The recording layer of the information recording area may be, for example, a write-once type optical disc made of a light absorbing film made of a cyanine organic dye and a metal film, or a phase change type optical disc made of a metal alloy film making a crystalline-amorphous phase change. . Further, it may be a magneto-optical disk including a recording layer of a rare earth-transition metal amorphous alloy and a dielectric layer. As a method of forming this information recording area, a sputtering method, a vacuum vapor deposition method or the like can be appropriately used.

As is apparent from the perspective view of the main part of the optical disc of the present invention shown in FIG. 2, the optical disc 42 has a pit formation region 42a in which pits are formed and a non-information recording region 4
It is divided into 2b. In the pit formation area 42a of the substrate 2 of the dummy disk portion 11, a pattern display area P representing the character "A" is surrounded by a group of dummy pits.
The dummy pit group is not formed in the character pattern portion "A", but is formed in the portion excluding the character pattern. That is, the pattern display area P of the pattern of the character "A" is a mirror surface. As shown in the figure, the dummy pit group is formed not only around the pattern display area P but also over the entire recording surface of the dummy disk portion 11. In addition,
The arrow R in the figure indicates the radial direction of the disk.

On the recording surface of the dummy disk portion 11 of the optical disk 42, reflected diffracted light is generated in the portion where the dummy pit 9 is formed, but reflected diffracted light is not generated in the mirror surface portion where the dummy pit 9 is not formed. Therefore, the display pattern becomes visible depending on the presence or absence of the reflected diffracted light. Further, a group of dummy pits may be formed inside and outside the pattern display area P, and the depth or density of the dummy pits formed inside the pattern display area and the dummy pits formed outside the pattern display area may be different. In such a case, since the intensity or the diffraction angle of the reflected diffracted light is different inside and outside the pattern display area, the pattern becomes visible.

In the above embodiment, the character is shown by the non-formed portion surrounded by the dummy pit group, but the character is not limited to the character. For example, it is possible to form patterns such as graphics and photographs showing the contents of the information signal recorded on the optical disc. Further, the dummy pit row group is formed in a concentric circle shape or a spiral shape at a predetermined pitch, or even if dummy pits are arranged on parallel straight lines at a predetermined pitch as long as they form a plane diffraction grating, for example, the Qinghai wave. It may be formed by a mosaic arrangement such as. Further, instead of the dummy pit group, a phase hologram may be formed in which the intensity distribution of the interference fringes between the reference light and the predetermined recording light such as a pattern is recorded as fine irregularities on the surface of the reflecting layer,
Rainbow holograms are particularly preferable.

As the disc accompanying information carried by the pattern display area P, the type of the optical disc such as LD, CD, DVD, CD, MO and the information recording area such as music information, graphic information, patent information, compression format information, etc. Examples include the type of recorded information, its index information, and content information such as title information. Further, the pattern display area P may be provided with a visually recognizable title, an optical pattern of characters, symbols, pictures for identification or the like, or a pattern readable by an optical device such as a barcode. The optical disk of the embodiment is specifically a DVD, for example, a substrate having a diameter of 12 cm and a thickness of 0.6 mm, 500 to 1500.
It can be formed as a double-sided optical disc including an angstrom-thick reflective film, a protective film having a thickness of 5 to 20 μm, and an adhesive layer having a thickness of several tens of μm. (Method of Manufacturing Optical Disc Master) Next, a method of manufacturing the optical disc master of the present invention will be described. To outline the manufacturing method of the present invention, a pattern to be displayed is divided into, for example, a main subject and a background, and a background portion pattern of a rainbow color display is collectively exposed by diffracted light reflected from a diffraction grating of a dummy pit. It is composed of a forming process group and a forming process group in which a pattern portion of a main subject on the background is individually and collectively exposed.

(Process for forming mask master for diffraction grating region) FIG. 3 shows a process for forming a mask master for a diffraction grating region which is a background in the method for manufacturing an optical disc master according to the first embodiment. First, as shown in FIG. 3a, chromium (Cr)
An opaque metal thin film 21 such as is formed on the main surface of the glass circular substrate 22 by sputtering or vapor deposition.

Next, as shown in FIG. 3b, a positive photoresist layer 23 is uniformly formed on the metal film 21 by spin coating. Next, as shown in FIG. 3c, the substrate 22 is rotated, and the spot of the recording beam 24 whose intensity is modulated according to the dummy signal is moved in the radial direction of the substrate at a constant speed, for example, to be irradiated and exposed to expose the photoresist layer 23. Then, latent images of dummy pit rows (or pregrooves) having a predetermined pitch are sequentially formed.

Next, as shown in FIG. 3d, a photoresist layer 23 having a latent image of dummy pit rows of photoresist is formed.
Are developed to dry the substrate 22, and post-baking is performed to form dummy pit rows. Next, as shown in FIG. 3e, the opaque metal film 21 is etched through dummy pit rows of a plurality of through holes of the photoresist layer 23 as a mask to spirally or concentrically circle the opaque metal thin film 21 at a predetermined pitch. Forming an opening.

Next, as shown in FIG. 3f, the photoresist layer is removed, and a mask master 25 having an opaque metal film for forming a diffraction grating region, in which openings are formed concentrically or spirally over substantially the entire surface, is formed. Form. By forming this mask master for each background display pattern, it is possible to store the mask master as a family of various backgrounds that can be repeatedly used. By using only this dummy master mask 25 for dummy signals, a dummy disk portion whose entire surface serves as a background for iridescent display can be created.

(Display Pattern Mask Forming Step) A display pattern mask having a light-transmitting portion on which a pattern such as a character, a symbol, or a picture, which is a main material for forming the display pattern area inside the diffraction grating area, is formed. Form. The display pattern mask may be a negative or positive film such as a monochrome photographic film on which a predetermined image is taken, or the like, and may have a light shielding portion and a light transmitting portion. Here, the film for the main display pattern and the like can be stored as various common subject families that can be repeatedly used.

(Developing Substrate Forming Step) A positive photoresist layer is uniformly formed on the main surface of the glass circular substrate by a spin coating method to form a developing substrate. (Exposure / Development Step) FIG. 4 shows an exposure / development step in the method for manufacturing an optical disk master according to the first embodiment.

First, as shown in FIG. 4a, the glass substrate 3
2 is provided with a developing substrate having a photoresist layer 31 formed thereon, and the mask master 25 is placed on the photoresist layer 31 as a mask, and then a collective exposure is performed from above to form a latent image of a background display pattern. It is formed as one exposure process. Here, the mask master 25 is collectively exposed so that the opaque metal film 21 on the glass substrate 32 faces the photoresist layer 31 side.

Next, as shown in FIG. 4b, a negative film 33 for the main display pattern, which is a pattern of the main subject such as characters, symbols and pictures, is used as a photo on which a latent image of the background display pattern is formed. It is arranged on the resist layer 31 and is exposed once again to form a latent image as a second exposure step. The order of the first and second exposure steps shown in FIGS. 4a and 4b can be exchanged, and a display pattern film is inserted between the mask master 25 and the resist layer 31 of the glass substrate 32 to perform both steps. Can be a single exposure step.

Next, as shown in FIG. 4c, the photoresist layer 31 is developed to form a master disk carrying a background dummy pit array and a portion surrounded by the dummy pit array of the main display pattern. To do. (Electroforming Step) Finally, as an electroforming step, a metal conductive film is uniformly laminated on the surface of the master disk and the resist dummy pit row. This is immersed in an electroforming tank to grow a metal film to form a stamper, and the stamper is separated from the glass substrate to prepare a stamper, that is, an optical disc master.

As described above, according to the present invention, the mask master can be repeatedly used, and it is not necessary to perform laser cutting for each pattern each time as in the conventional case, and not only the main display pattern (negative film) but also the background display pattern. Each (mask master) can be saved as a family, the combinations of them will be rich, and stamper duplication will be easier.

(Duplicate Assembling Step) Using this stamper, a replica plastic substrate is prepared by resin injection molding, and a reflective film and a protective film are sequentially laminated on the pit surface of the replica to prepare a dummy disk portion. The separately formed information recording disk portion is attached via an adhesive layer to obtain the double-sided optical disk shown in FIG.

In the thus obtained double-sided optical disc, so-called pit art is obtained in which the entire background shines rainbow-colored, and the main display pattern portion becomes a mirror surface and is deeply reflected from the whitish whole of the dummy pit area. The manufacturing yield of double-sided optical disks is improved. (Manufacturing Method of Optical Disc Master by Other Mask Master Making Process) FIG. 5 shows a background mask master making process in the optical disc master manufacturing method according to the second embodiment. The first embodiment includes a background mask master disk forming process using lithography using a photoresist layer, but the second embodiment does not use lithography in the background mask master disk manufacturing process, so the process is simplified. .

First, as shown in FIG. 5a, an opaque metal thin film 51 of chromium or the like is formed on a glass substrate 52 by sputtering or vapor deposition. Next, as shown in FIG. 5b, without forming a photoresist layer, the photoresist layer 53 is irradiated with a laser beam 54 whose intensity is modulated by a dummy signal to selectively melt and vaporize or sublimate the photoresist layer 53 to form a pit. It is possible to form a mask master in which rows (through holes) are directly formed.

This makes it possible to form a mask master of an opaque metal thin film having pit row openings on the entire surface. Thus, according to the second embodiment, the number of steps can be reduced. In the case of forming a phase hologram, if an amplitude hologram in which interference fringes are recorded in shades is formed in advance and the photoresist layer is exposed using this as a mask, an optical disc master can be obtained by the exposure and development process shown in FIG. it can.

[0036]

As described above, according to the present invention, in the method for manufacturing an optical disk master, the pattern to be displayed is divided into, for example, the main material and the background, and the background is a rainbow caused by the diffracted light reflected from the diffraction grating. It consists of a group of steps to form a background pattern by using common color display or hologram display, and a group of steps to form a pattern part of the main subject individually, so that the mask master of the background display pattern can be used repeatedly. , It is possible to easily duplicate the signal of the background display pattern as a master disc family. Further, unlike the conventional case, it is not necessary to perform laser cutting for each main pattern each time, and a variety of combinations of the background pattern and the main display pattern are provided, so that various stampers can be easily manufactured. In addition, it is possible to display a sufficiently large pattern even with a small high-density optical disk such as a DVD.

[Brief description of drawings]

FIG. 1 is a schematic partial cross-sectional view of an optical disc according to an embodiment of the present invention.

FIG. 2 is a perspective view of an optical disc according to an embodiment of the present invention.

FIG. 3 is a cross-sectional view of a substrate in a method of manufacturing an optical disc master according to the present invention.

FIG. 4 is a cross-sectional view of a substrate in a method for manufacturing an optical disc master according to the present invention.

FIG. 5 is a cross-sectional view of a substrate in a method for manufacturing an optical disc master according to the present invention.

[Explanation of symbols for main parts]

 2, 8 substrate 3, 7 reflective layer 4, 6 protective film 5 adhesive layer 9 dummy pit 10 information pit 11 dummy disk section 12 information recording disk section P pattern display area 21, 51 opaque metal thin film 22, 32, 52 glass substrate 23, 31 photoresist 24, 54 laser beam 33 negative film for main display pattern 42 optical disc 43 dummy disc master

Claims (6)

[Claims] 1. One of the recording surfaces has a recording track formed of concentric circles or spirals composed of a pit row for carrying an information signal, and the other of the recording surfaces has a diffraction grating region for generating diffracted light by incident light. A method of manufacturing an optical disc master for a reflective optical disc having a pit row on both recording surfaces, which has a display pattern area that does not generate diffracted light by the incident light formed in the diffraction grating area. And a step of forming a mask master comprising a translucent substrate and an opaque thin film formed on the translucent substrate and having an opening for forming the diffraction grating region, and forming a display pattern region Forming a mask for a display pattern having a light-transmitting portion for forming, a step of forming a developing substrate having a photoresist layer on a main surface, and the photoresist of the developing substrate. A first exposure step in which the mask master is placed on a photoresist layer, and the photoresist layer is collectively exposed through the openings of the opaque thin film; and the display pattern mask on the photoresist layer of the developing substrate. And exposing the photoresist layer collectively through the light transmitting portion, and developing the development substrate having the photoresist layer exposed in the first and second exposure steps. A method of manufacturing an optical disc master, comprising: 2. The method of manufacturing an optical disc master according to claim 1, wherein the diffraction grating region is a dummy pit row or a pre-groove formed in a spiral shape or a concentric shape at a predetermined pitch. 3. The method of manufacturing an optical disk master according to claim 1, wherein the diffraction grating region is a dummy pit row or a pre-groove formed in parallel straight lines at a predetermined pitch. 4. The method of manufacturing an optical disk master according to claim 1, wherein the diffraction grating region is a hologram. 5. The method of manufacturing an optical disk master according to claim 1, wherein the order of the first exposure step and the second exposure step is exchanged. 6. The method according to claim 1, wherein the mask master and the display pattern mask are superposed on the photoresist layer, and the first exposure step and the second exposure step are performed simultaneously. Optical disc master manufacturing method.