KR20030071044A - Photo Disc and Method for manufacturing the same - Google Patents

Abstract

PURPOSE: An optical disk and a method for fabricating the optical disk are provided to fabricate the optical disk using upper and lower substrates that have different thicknesses and different components. CONSTITUTION: An optical disk includes the first substrate(101) to which a pre-groove or a pre-pit track is transferred, the first information recording layer(103) formed on the first substrate, and a semitransparent layer(105) formed on the first information recording layer. The optical disk further includes the first adhesive layer(107) formed on the semitransparent layer, the second information recording layer(109) and a reflection film(111) formed on the second substrate, the second adhesive layer(113) formed on the reflection film, and the third substrate(113) whose flat face adhere onto the second adhesive layer, corresponding to the first substrate.

Description

Optical Disc and Method for Manufacturing the Same {Photo Disc and Method for manufacturing the same}

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical disk and a method of manufacturing the same, and to an optical disk and a method of manufacturing the same, which can use a substrate having a flat surface corresponding to the thinning of the substrate or the change of the substrate material.

Recently, read-only memory (ROM) of CD, DVD (Digital Versatile Disc) system, recordable (-R) that can record information once, and can read, write and erase information repeatedly Rewritable (-RAM, -RW) optical discs have been developed and commercialized. Such optical disks take the principle that a laser light source first enters through a transparent substrate medium, passes through an information recording layer, is reflected on a reflective layer, and a photo detector detects the reflected laser.

Such a DVD is currently based on a form in which two substrates having a thickness of 0.6 mm and a diameter of 12 cm are bonded to each other. However, even in the same DVD system, much research has been made to improve the recording density of an optical disk.

As a result, DVD (-5 / -9 / -10 / -18) type discs with various structures have been developed to form a new optical disc market. DVD-5 type optical discs have a recording capacity of 4.7 Gbyte on one side. That's about seven times the size of a CD's 780MB.

Further, the improvement of the recording density can be achieved by miniaturization of optical spots, efficiency of signal processing of modulation codes or error correction codes, physical changes of optical disks, ie pit size, reduction of track pitch, increase of information recording layers, The distance between the light incident surface and the light reflecting surface is reduced (thickness reduction CD: 1.2 mm, DVD: 0.6 mm). Here, a read-only memory (-ROM) disk will be described as an example.

Among the overall production process of the DVD family optical disc, let's take a look at the production process of the DVD-5type.

1A to 1D are sectional views of the manufacturing process of the DVD-5 type.

As shown in Figs. 1A to 1D, the overall manufacturing process of a DVD-5 type optical disc is firstly a mastering process for making a stamper 1 and a first process based on the stamper 1; It comprises a molding process for injection or compression molding the substrate (2). In this case, the second substrate 3 facing the first substrate 2 is a flat substrate formed using a stamper that undergoes the injection or compression molding process but does not have any surface shape.

Further, the information recording layer 4 is formed by vacuum deposition of the information recording layer 4 and the reflective film 5 on the first substrate 2, and by using an adhesive 6 such as a UV light reactive adhesive. And a bonding process for bonding the first substrate 2 and the second substrate 3 on which the reflective film 5 is deposited.

Here, a pre-groove (7 in FIG. 1B) between the protrusions and the protrusions formed on the surface of the first substrate 2 on which the molding process is performed using the stamper 1 (a write-once and a repeatable recording disc). In this case, a separate information recording layer is formed by using a dye or a recording film on the pre-groove, whereas in the case of reproduction only, the pre-fit pattern is formed even after the reflective layer on the pre-pit track is formed. A track with a pre-pit pattern will be present and this surface will be referred to as an information recording layer), and after forming a small hole instead of the pregroove 7, the small hole will be a disc. What is formed in a spiral shape on the surface is called a free fit track (8 in FIG. 1B). Of course, the pregroove 7 and the prepit track 8 may be formed at the same time.

In addition, the information recording layer 4 may be formed at an interface between the first substrate 2 and the reflective film 5 to store information.

This type of DVD-5 has a single information recording layer, so the storage density of the information is low. Therefore, in recent years, DVDs (-9 / -10 / -18 types) having a large number of information recording layers have emerged to increase the amount of information storage.

As shown in Figs. 2A to 2C, the optical disc according to the prior art has multilayer information recording layers 4a, 4b, 4c and 4d. Among them, DVD-9 (FIG. 2A) and DVD-18 (FIG. 2C) format discs having a single-side dual-layer structure on a single surface are generally called dual layer discs. Let's look at an example of a ROM type disk for a conventional production method for making a dual layer disk.

First, after forming the first information recording layer 4a on the first substrate 2 and forming the translucent film 9 on the substrate having the free fit track, the adhesive layer 11 is formed on the translucent film 9. After forming a predetermined thickness of a material called 'photo-polymerizable polymer' on the adhesive layer, another free-fit track is made by bonding the stamper with the stamper to form a second information recording layer 4b.

By forming a reflective film on the new free-fit track thus produced, a second information recording layer 4b can be made to produce a dual-layer disc having two information recording layers on a single-sided single substrate on which a laser light source is incident.

Second, as in the method of manufacturing a DVD-10 type disk, a reflective film 10a is formed on one substrate and a reflective film 10b is formed on the other side, and then a bonding method is performed.

However, the first method has a disadvantage in that productivity is low in mass production due to the complicated manufacturing process, while the second method is suitable when both substrates have the same thickness as in the DVD system, but as in the example of the next-generation optical disk. If one substrate is very thin, it will be difficult to manufacture.

In order to realize such next-generation high-density optical disk, a method of increasing recording capacity while maintaining the current DVD disk structure and largely changing the disk structure has been attempted. In the first case, the short wavelength of the light source and the new signal processing are attempted. It is possible to increase the recording density to about 15GB by the technique.In the second case, the numerical aperture of the objective lens (NA) is increased not only by shortening the wavelength of the light source but also by reducing the beam spot diameter by about 20 to 25GB. Capacity can be realized.

On the other hand, when a lens having a high numerical aperture is used, acomer aberration, which is a kind of wavefront aberration, is rapidly increased, and there is a method of reducing the distance that the laser beam passes through the disk, that is, the thickness of the light transmitting layer, in order to reduce such aberration.

For example, a structure using a 0.1 mm cover layer has been proposed in a next-generation optical disk of 20 GB or more. An existing disk (eg, CD) in which a light source is incident and reflected back to a thick substrate including free groove or free fit track information is proposed. Or DVD), which enters a thin cover layer (which acts as an optical guide), passes through a recording layer formed on a pre-groove or pre-fit track previously transferred from a stamper to a 1.1 mm thick substrate surface, and then back on the reflective layer. It is characterized by having a return structure. Therefore, unlike the conventional cover layer need to be optically transparent, but the substrate is not necessarily transparent is an important difference from the DVD-based or early HD (high definition) class optical discs that have been developed up to now.

As described above, an optical disk having a multilayer information recording layer of the prior art has the following problems.

In the manufacturing process of the multi-layered information recording layer according to the prior art, when a plurality of information recording layers are molded and bonded to each of the first substrate and the second substrate, the manufacturing process becomes complicated and the productivity is lowered. It is suitable when the thickness of the second substrate is the same, but it is difficult to manufacture when one substrate (preferably a cover layer) is very thin as in an example of the next generation optical disk or when a strong material such as metal is required. .

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and includes two information recording layers and a flat surface on a single optical guide on which a laser light source is incident in order to cope with the thinning of the substrate or the change of the substrate material. An optical disk capable of bonding to another substrate having a face.

1A to 1D are sectional views of the manufacturing process of the DVD-5 type.

2A to 2C are cross-sectional views of the DVD (-9 / -10 / -18 type).

3 is a cross-sectional view of an optical disk of the present invention.

4A to 4E are cross-sectional views of the manufacturing process of the optical disk according to the present invention.

Explanation of symbols for main parts of the drawings

101: first substrate 103: first information recording layer

105: semi-permeable membrane 107: first adhesive layer

109: second information recording layer 111: reflective film

113: second adhesive layer 115: third substrate

117: second substrate

An optical disk of the present invention for achieving the above object comprises a first substrate on which a pre-groove or pre-pit track is transferred, and a first information recording layer formed on the first substrate. And a translucent layer formed on the first information recording layer, a first adhesive layer formed on the translucent layer, a second information recording layer and a reflective film formed from a second substrate and stripped on the first adhesive layer, and on the reflective film image And a third substrate having a flat surface adhered to the second adhesive layer in correspondence with the first substrate. Further, another feature of the present invention is a process of transferring a pre-groove or pre-pit track on a first substrate to form a first information recording layer, and the first information recording. Forming a translucent layer on the layer, forming a first adhesive layer on the translucent layer, forming a reflective film and a second information recording layer on a second substrate, and forming the first and second substrates. Peeling the second information recording layer and the reflective film from the second substrate after adhesion; forming a second adhesive layer on the reflective film; and forming a third adhesive layer on the second adhesive layer corresponding to the first substrate. An optical disk manufacturing method comprising the step of positioning a substrate.

The optical disk of the present invention is bonded to another substrate having two information recording layers and a flat surface on a single substrate serving as an optical guide through which the laser light source is incident to increase the recording density.

Hereinafter, an optical disk according to the present invention will be described in detail with reference to the drawings.

3 is a cross-sectional view of an optical disk according to the first embodiment of the present invention.

As shown in FIG. 3, the optical disk according to the first embodiment of the present invention includes a first substrate 101 on which a pre-groove or a pre-pit track is formed, and the first substrate. A first information recording layer 103 formed on the substrate 101, a translucent film 105 formed on the first information recording layer 103, and a first formed on the first information recording layer 105. An adhesive layer 107, a second information recording layer 109 transferred from a second substrate (not shown) formed with a pregroove or a prefit track corresponding to the first information recording layer 103, and the second A third film adhered to the first substrate 101 by the reflective film 111 formed on the information recording layer 109, the second adhesive layer 113 formed on the reflective layer 111, and the adhesive layer 113. It is configured to include a substrate (115).

In the optical disk of the present invention, a reflective film 111 and a second information recording layer 109 are sequentially formed on the second substrate by using a material having poor interfacial adhesion with the reflective film 111. From the second substrate, the second information recording layer 109 and the reflective film 111 are attached to the first adhesive layer 107 on the first substrate 101. In addition, the second information recording layer 109 and the reflective film 111 are separated from the second substrate, and the second adhesive layer 113 is formed after the second adhesive layer 113 is formed on the reflective film 111. The third substrate 115 is adhered to it.

In this case, when the second substrate is made of a material having a strong interface adhesive force with the reflective film 111, a process in which ions of the target material of the reflective film 111 are deposited on the second substrate through electrical and physical post processing. Since the surface adhesive force can be weakened in the above, when the translucent film 105 formed on the first substrate 101 and the second information recording layer 109 or the reflective film 111 of the second substrate are adhered, the first The interfacial adhesion between the adhesive layer 107, the translucent film 105, the first adhesive layer 107, the second information recording layer 109, the second information recording layer 109, and the reflective film 111 is the same. By better than the interfacial adhesion between the reflective film 111 and the second substrate, the second information recording layer 109 and the reflective film 111 can be separated cleanly and transferred to the first substrate 101. Diversification and separation of options for materials or bonding processes The ease can be achieved.

Therefore, the second substrate requires a material having good transfer characteristics and poor interfacial adhesion with the reflective film in order to form a pre-groove or a pre-fit track on the surface, but one of the representative characteristics of the polymer resin of the 'fluoropolymer' type is low. It has a low frictional coefficient.

Such a 'fluoropolymer' polymer resin is PTFE (Polytetrafluoroethylene), which has a low crystallinity due to its high crystallinity and melting point, and thus a low molecular PTFE or fluorine-replaced 'fluoropolymer'. Polymeric resin of the type can be used.

Substrates made of such 'fluoropolymer' polymer resins have excellent chemical resistance and are insoluble in general organic solvents and are not significantly affected by high temperature and high concentrations of acids and bases. Particles (particles) can be easily removed chemically and physically has the advantage of recycling. In addition, a polymer resin or other material having poor interface adhesion with the reflective film can be used.

On the other hand, since a reflective film is present on the second substrate in the bonding process and is optically opaque, bonding is performed by irradiating and curing UV to the optically transparent first substrate 101 and the translucent film 105, or to A component and B The component can be bonded by using a two-component adhesive or the like where the components meet and bond chemically.

Therefore, the optical disk of the present invention is optically transparent on one side and the other is transparent or not on the other side without the same thickness of the upper and lower substrates as in the example of the next-generation optical disk structure using a 0.1mm cover layer And an optical disk that can use a flat substrate using a material such as a metal.

Although not shown, an optical disk according to another embodiment of the present invention has a DVD-18 type having two information recording layers on both upper and lower substrates instead of the first and third substrates 101 and 115. As in the above, an optical disc having a total of four information recording layers or two layers on one side, one layer on one side, and three information recording layers on one side.

Referring to the drawings with respect to the manufacturing method of the optical disk of the present invention configured as described above in detail as follows.

4A to 4E are cross-sectional views of the manufacturing process of the optical disk according to the first embodiment of the present invention.

First, as shown in FIG. 4A, a pregroove or a prefit track is formed on the second substrate 117 using a stamper, and then a reflective film is formed through a sputtering process, and the like on the reflective film 111. The second information recording layer 109 is formed on the substrate.

At the same time, as shown in Fig. 4B, a pre groove or pre-fit track on the stamper surface is transferred to the first substrate 101 to form a first information recording layer 103, and the first information recording layer 103 ), A semitransparent film 105 is formed through a sputtering process or the like.

In addition, as shown in Figure 4c, after the first adhesive layer 107, such as UV light adhesive on the adhesive surface of the first substrate 101 and the second substrate 117 is applied (bonding, such as UV curing) Through the process or the like, the first substrate 101 and the second substrate 117 are separated as shown in FIG. 4D.

In this case, a first information recording layer 103, a translucent film 105, a first adhesive layer 107, a second information recording layer 109, and a reflective film 111 layer are sequentially formed on the first substrate 101. do.

Finally, as shown in FIG. 4E, a second adhesive layer 113, such as a UV light adhesive, is formed on the reflective film 111 of the first substrate 101, and is free on the second adhesive layer 113. After the third substrate 115 without grooves or pre-fit tracks is positioned, the second adhesive layer 113 is integrated through a bonding process such as UV curing, thereby completing the manufacturing process of the dual layer optical disc of the dual information recording layer. do.

On the other hand, although not shown, the optical disk manufacturing method according to the second embodiment of the present invention is a reflective film and the second information recording layer on the first substrate in the reverse order of the optical disk manufacturing method according to the first embodiment of the present invention. After forming a first information recording layer and a semi-transparent film on the second substrate, the second information recording layer and the semi-transparent film are bonded using a first adhesive layer, and the second substrate is separated.

In addition, after forming a second adhesive layer on the translucent film formed on the first substrate, a third substrate having a flat surface (which serves as a light guide to which a laser light source is incident) is placed, and the bonding process of the second adhesive layer is performed. Integrate through the back.

In the same manner as described above, a multi-layer optical disc according to the present invention having three and four information recording layers can be produced.

Therefore, in the optical disk of the present invention, since the third substrate 115 has a flat surface, it is difficult to form a pregroove or a prepit track using a stamper, or a thin film having a thickness of 0.1 mm or less may be formed on the third substrate 115. Can be used as)

As a result, even when the upper and lower substrate thicknesses of the optical disk composed of two substrates are not the same, or when the materials forming the upper and lower substrates are different, the dual layer disk manufacturing method of the present invention can be easily applied. It offers advantages.

As described above, the optical disk having the multilayer information recording layer of the present invention has the following effects.

In the optical disk having the multi-layered information recording layer of the present invention, since one of the upper and lower substrates has a flat surface, the thickness of the upper and lower substrates is different or the upper and lower substrates are made of materials of different components. There is an effect that can produce an optical disk.

Claims (9)

A first substrate to which a pre-groove or pre-pit track has been transferred; A first information recording layer formed on said first substrate, A translucent layer formed on said first information recording layer, A first adhesive layer formed on the translucent layer, A second information recording layer and a reflective film formed from a second substrate and stripped on said first adhesive layer; A second adhesive layer formed on the reflective film; And a third substrate having a flat surface adhered to the second adhesive layer corresponding to the first substrate. The optical disc of claim 1, wherein the first substrate uses a transparent material. 2. The interfacial adhesion between the semitransmissive film and the first adhesive layer, the first adhesive layer and the second information recording layer, and the second information recording layer and the reflective film is superior to that of the second substrate and the reflective film. An optical disk, characterized in that. A first substrate to which a pre-groove or pre-pit track has been transferred; A reflective film formed on the first substrate; A first information recording layer formed on the reflective film; A first adhesive layer formed on said first information recording layer, A second information recording layer and a semi-permeable film formed from a second substrate and peeled off on the first adhesive layer; A second adhesive layer formed on the transflective film, And a third substrate having a flat surface adhered to the second adhesive layer corresponding to the first substrate. 5. The method according to claim 4, wherein the interfacial adhesion between the first information recording layer, the first adhesive layer, the first adhesive layer, and the second information recording layer, the second information recording layer, and the semi-permeable film is determined by An optical disk, which is superior to interfacial adhesion. The optical disc according to any one of claims 1 to 4, wherein the first adhesive layer and the second adhesive layer are UV light adhesives. Transferring a pre-groove or re-pit track onto the first substrate to form a first information recording layer; Forming a translucent layer on the first information recording layer; Forming a first adhesive layer on the translucent layer; Forming a reflective film and a second information recording layer on the second substrate; Peeling the second information recording layer and the reflective film from the second substrate after adhering the first and second substrates; Forming a second adhesive layer on the reflective film; And positioning a third substrate on the second adhesive layer corresponding to the first substrate. Transferring a pre-groove or pre-pit track onto the first substrate to form a reflective film and a first information recording layer; Forming a first adhesive layer on the first information recording layer; Forming a translucent film and a second information recording layer on the second substrate; Peeling the second information recording layer and the translucent film from the second substrate after adhering the first and second substrates; Forming a second adhesive layer on the translucent film; And positioning a third substrate on the second adhesive layer corresponding to the first substrate. 9. The method of any one of claims 7 and 8, further comprising the step of transferring the pregroove or prefit track onto the second substrate.