JPH052785A - Reproducing method for optical disk - Google Patents

Abstract

PURPOSE:To provide the reproducing method for an optical disk which can rapidly peel the contact surface of a stamper and a radiation curing resin. CONSTITUTION:The region where the radiation curing resin 6 is formed is irradiated with radiations 8 by having the prescribed distribution of radiation doses prior to press welding of the stamper 10 to the above-mentioned radiation curing resin 6 at the time of reproducing the optical disk by press welding the stamper 10 to the radiation curing resin 6 formed on a substrate 2. The resin is half cured in this way and the adhesive force at the peeling initiation point is decreased.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for reproducing an optical disc on which information such as a video disc, a digital audio disc, a document file disc or the like is recorded.

[0002]

2. Description of the Related Art Conventionally, injection molding, compression molding,
The hot stamp method, cast molding method and the like are known. The injection molding method is a method in which a molten thermoplastic resin is injected and injected under high pressure into a cavity of a mold under high temperature and high pressure to reproduce, and the compression molding method is performed by inserting the thermoplastic resin into the mold. After molding under high temperature and high pressure, it is a method of replicating by cooling the mold and curing the resin, and the hot stamper method is a mold cooled to a film of heated thermoplastic resin. It is a method of pressing and molding. Each of these methods has excellent productivity, but in recent years, densities have been increasing, and very minute irregularities (inverted pits or grooves) on the mold have been achieved.
However, there are disadvantages in that the transfer accuracy is inferior for replicating, and the manufacturing equipment is large-scale and expensive because the process is performed under high temperature and high pressure.

On the other hand, the injection molding method is a so-called injection molding method in which the resin is cured by irradiation with ultraviolet rays or electron beams.
By using a radiation-curable resin, the molding time is shortened and the transfer accuracy is good, so that attention has been paid to it. As a method of duplicating an optical disc using this radiation-curable resin, a stamper having pits or groups formed on the surface thereof and a transparent resin substrate are opposed to each other, and the radiation-curable resin is injected into the gap to form a transparent resin substrate. By irradiating ultraviolet rays from the back side to cure the radiation curable resin and to bond it to the transparent resin substrate, and then peeling between the stamper and the radiation curable resin, pits in which the transparent resin substrate and the stamper are reversed, or There is a method of obtaining a duplicate disk in which the groove-transferred radiation-curing resin is integrated.

[0004]

By the way, in recent years, optical discs on which various types of information are recorded or which can be recorded have a tendency to be produced in small quantities and in a large variety of products. As a production system therefor, production management is easy, Moreover, single-wafer production systems with short lead times are receiving attention. In this production system, it is required that the individual processes be synchronized and have high speed and high reliability. However, the above-mentioned cast molding method using a radiation curable resin having good transferability will reduce productivity in the molding process. There were the following drawbacks. That is, in the conventional cast molding method using a radiation curable resin, a liquid radiation curable resin is injected or dropped between the stamper and the transparent substrate, and then these are pressed to spread the radiation curable resin thinly, and thereafter, Ultraviolet rays were irradiated from the substrate side to cure.

However, in the method of bringing the liquid resin into close contact with the stamper to cure it, in order to separate the substrate, which is integrated with the radiation-curable resin having the uneven pits or grooves transferred to the surface after the curing, from the stamper, It was necessary to perform the treatment slowly so that there was no residue on the stamper, and to prevent the substrate from being destroyed, the substrate was bent with a small force so that the peeling point gradually moved on the peeling surface. Therefore, in such a conventional method, a step of injecting or dropping a radiation curable resin between the transparent substrate and the stamper to spread the pressure, a step of irradiating with radiation and curing, and a step of peeling the substrate from the stamper are performed. The productivity was extremely poor because they were all performed on the same stage.

Therefore, the present inventor has devised a method for improving productivity by separating the above steps. In this method, a radiation-curable resin is applied in a semi-cured state on a transparent substrate in advance, and then a stamper is pressure-bonded to the semi-cured radiation-cured resin surface to transfer pits or grooves.
Although this method is slightly inferior to the transfer method in the conventional method, the signal characteristic is superior to that in the conventional injection molding method. Further, in this method, a resin having an excellent adhesion to the transparent substrate can be used, and since it is in a semi-cured state, the releasability from the stamper is relatively good. However, in this method, the substrate had to be bent in order to set the peeling start point. Moreover, since the adhesion force between the contact surface of the stamper and the radiation curable resin is rapidly changing within the contact surface, a large force is required at the time of peeling, and at the peeling start point There was room for improvement because minute breakage occurred, which could reduce product quality and cause stamper deterioration.

The present invention focuses on the above problems,
It was created to solve this effectively. It is an object of the present invention to provide a method for duplicating an optical disc, which can quickly separate the contact surface between the stamper and the radiation curable resin.

[0008]

In order to solve the above-mentioned problems, the present invention provides a method of copying an optical disk by pressing a stamper onto a radiation-curable resin formed on a substrate, wherein the stamper is radiation-cured. Prior to pressure-bonding to the resin, irradiation is performed so that the stamper after the pressure-bonding and the radiation-curable resin are easily separated from each other, so that a region where the radiation-curable resin is formed has a predetermined distribution of radiation dose. Then, there is a step of bringing the radiation-curable resin into a semi-cured state.

[0009]

Since the present invention is configured as described above, a predetermined distribution is formed in the adhesive force between the stamper and the radiation curable resin, and the contact between the stamper and the radiation curable resin is extremely small. Therefore, the peeling is started with a small force at the peeling start point, and the peeling point moves smoothly, so that the peeling operation can be performed accurately and at high speed.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An optical disk duplication method according to the present invention will be described in detail below with reference to the accompanying drawings. FIG. 1 is an explanatory diagram for explaining one embodiment of the method of the present invention. First, the overall flow of this duplication method will be briefly described. As shown in FIG. 1A, reference numeral 2 is a substrate made of a radiation-transmissive material formed in a circular flat plate shape, and a central hole 4 is formed in the central portion of the substrate 2. The substrate 2 is made of, for example, a transparent resin in order to transmit radiation. Here, the radiation includes not only electromagnetic waves in the range of ultraviolet rays to infrared rays but also electromagnetic waves having a short wavelength such as γ-rays and particle beams such as electron beams.

First, the radiation curable resin 6 is applied in a ring shape on the upper surface of the substrate 2. The applied portion is only the area to which the pits, grooves, etc., which are information signals, are to be transferred, and an effective means therefor is, for example, a printing method. In this printing method, for example, as a screen used in the case of screen printing, a screen having a high mesh number, a wire having a small diameter, or preferably a metal sheet which has been subjected to surface treatment by etching into an appropriate pattern, It is preferable that the resin surface after printing is flat. This resin surface is made smooth by a heating roller or the like, if necessary. Further, as the radiation curable resin 6, a thin film can be obtained by using a resin having a low viscosity.
The amount of warp can be reduced. As a method for obtaining a thin coating film having a smooth surface, a spray method may be used instead. For example, a radiation-curable resin having a viscosity of 10 to 50 centipoise is spray-coated on the substrate 2 in which only the information area is exposed by masking, unlike the case of screen printing, there is no contact with the substrate surface. There is an advantage that the bonding surface between the cured resin 6 and the substrate 2 can be cleaned and the bonding can be performed firmly.

Next, as shown in FIG. 1B, with the substrate 2 placed on the transparent substrate holding plate 3, the radiation-curable resin 6 application surface 2a of the substrate 2, that is, the stamper transfer surface. As seen from the back side, for example, ultraviolet rays 8 are applied as radiation from the back side. The ultraviolet rays 8 pass through the substrate 2 and are absorbed by the radiation curable resin 6. At this time, the amount of ultraviolet rays to be irradiated is set so that the radiation curable resin 6 is in a semi-cured state in which the resin 6 still has viscosity. Here, on the lower surface of the substrate holding plate 3, a metal film 5 is formed in a donut shape so as to have a predetermined distribution of the radiation dose which is a feature of the present invention, as described later. Next, as shown in FIG. 1C, the stamper 1 is placed on the upper surface of the radiation-cured resin 6 in the semi-cured state.
0 is pressure-bonded to the stamper 10, and the pit 12 or groove previously formed as information on the stamper 10 is reversely transferred.

Next, the stamper 10 and the radiation transparent substrate 2
Is peeled off on the transfer surface 14, and at this time, maintaining the transferred pit shape on the upper surface of the radiation curable resin 6 is the reason why the radiation curable resin 6 is in the semi-cured state as described above. .. When the pit shape is not sufficiently retained, the ultraviolet ray 8 may be irradiated from the back surface side of the radiation transmissive substrate 2 under pressure. The semi-cured radiation-curable resin 6 that retains the pit or groove shape is shown in FIG.
As shown in (d), it is completely cured by further irradiating with ultraviolet rays 8b from the back side of the radiation transmissive substrate 2,
Thereby, the optical disc 16 is completed.

By the way, as shown in FIG. 1B, when the radiation transmitting resin 6 is brought into a semi-cured state, the substrate holding plate 3 having the ring-shaped metal film 5 formed on its lower surface is used. However, this metal film 3 is formed by vapor deposition or the like so that the ultraviolet transmittance thereof has a distribution as shown in FIG. That is, it has a large UV transmittance near the center and the vicinity of the outer periphery of the substrate 2, a relatively small transmittance between them, and is set to be point-symmetrical at the center of the substrate 2. The transfer area A-B to which the information of the stamper 10 is actually transferred is set to have a constant transmittance with a relatively low value, and the radiation-curable resin is formed or applied between the application areas A1-B1. It is set to be wider than the transfer area, and the radiation transmittance is continuously increased in the coating area outside the transfer area. With this configuration, the radiation curable resin 6 corresponding to the transfer area is semi-cured to a hardness suitable for the next transfer operation, and the resin of the inner and outer parts thereof is semi-cured to be slightly harder. Therefore, the degree of adhesion at that portion is reduced, and the stamper 10 can be easily peeled off. In this case, the transmittance distribution may be set so as to increase the transmittance only at the inner peripheral end of the ring-shaped resin 6 as shown by the one-dot chain line in FIG.

As a means for setting the amount of ultraviolet rays radiated by the resin to a predetermined distribution as shown in FIG. 2, for example, as shown in FIG. 3, a transparent circular light shielding plate 18 is detachably attached to the substrate holding plate. 3 on the surface of the light-shielding plate 18 shown in FIG.
You may make it form the ring-shaped metal film 5 similar to what is shown to (b). Then, when the radiation curable resin 6 is semi-cured, the light shielding plate 18 is superposed so as to be interposed between the substrate holding plate 3 and the substrate 2, and ultraviolet rays are irradiated from below. In this case, since the replacement of the light shielding plate 18 is very easy, the light shielding amount can be changed by immediately using the corresponding light shielding plate according to the change in the light amount of the ultraviolet light source, and therefore, the semi-curing of the radiation curable resin can be performed. It is possible to maintain a constant degree.

As another means, as shown in FIG. 4, a circular rotating disk 22 made of, for example, a metal plate having an opening 20 is formed, and the center of rotation O coincides with the central hole 4 of the substrate 2. Then, it may be rotated between the substrate 2 and the ultraviolet source. The shape of the opening 20 is set so that the distribution of the amount of ultraviolet rays passing through the opening 20 draws a curve similar to that of FIG. 2, so that the radian of the opening width in the circumferential direction of the opening 20 is shown in FIG. Determine to be the same as the curve. As such a rotating disk 22, a metal film may be formed on a circular transparent glass substrate, and an opening may be formed on the metal film by pattern etching or the like. In this case, if the glass surface of the opening is rough, the transmitted ultraviolet rays become diffused light, so that uniform ultraviolet irradiation can be performed.

As shown in FIG. 1 (c), pits or grooves are transferred and peeled from the radiation-cured resin 6 semi-cured as described above. In this case, for example, FIG.
The apparatus shown in FIG. As shown in the figure, the stamper 10 is integrally bonded and fixed to the lower end of the stamper holding block 26. At the center of the stamper block 26, the small chamber 2 opened downward
In this small chamber 28, a vertically movable disc pressing rod 32 partially supported by a sliding sealing member 30 such as an O-ring is provided. A gas pressure inlet 34 for supplying pressurized gas to the small chamber 28 is connected to the small chamber 28. The circular substrate 2 is placed on the substrate holding plate 3 by being aligned by the center alignment protrusion 36, and the semi-cured radiation curing resin 6 is placed on the donut on the substrate 2. It is patterned. The transfer of pits or grooves is performed by applying pressure between the stamper holding block 26 and the substrate holding plate 3 so that the stamper 10 and the radiation curable resin 6 are pressure bonded. When the semi-curing of the resin is insufficient during this pressurization, an appropriate amount of ultraviolet rays 8 may be irradiated from the back surface of the substrate holding plate 3.

In order to perform the peeling operation, first, the stamper 10 and the substrate 2 are pressure-bonded to each other, the pressure is stopped, and the stamper 10 is lifted together with the stamper holding block 26. At this time, the disc pressing rod 32 is projected from the stamper holding block 26 to press the central portion of the substrate,
Pressurized air or pressurized nitrogen gas is supplied into the small chamber 24 through the gas pressure inlet 34 to increase the pressure in the small chamber 24. Then, the gas pressure causes the substrate 2 and the stamper 10 to
The substrate 2 is peeled from the inner circumference toward the outer circumference, and the substrate 2 is returned onto the substrate holding plate 3. At the time of this peeling, the inner peripheral edge and the outer peripheral edge of the ring-shaped pattern of the radiation curable resin 6 have a higher semi-curing degree than the information transfer area. Adhesion is lost, and therefore peeling starts from the inner peripheral end of the ring-shaped pattern of the radiation curable resin 6, and this peeling point gradually and smoothly moves toward the outer periphery of the pattern. ..

As described above, the ring-shaped radiation curable resin 6 is used.
Since the adhesion force at the inner peripheral edge or the outer peripheral edge of the resin is made relatively small, peeling is started with a minute force at the peeling start point, and this peeling point moves smoothly. No residue is generated, and the peeling operation can be performed quickly and without breaking the substrate. Further, at the peeling start point, since the curing degree of the radiation curable resin is increased, the transferability is deteriorated. However, since the peeling start point corresponds to the portion outside the signal area in the stamper, the characteristics of the optical disc are affected. Never give. Also,
Since the peeling operation can be easily performed, the device having the structure shown in FIG. 6 may be used by removing the disc pressing rod 36 having a complicated structure from the device shown in FIG.

That is, as shown in the figure, the substrate holding plate 3 is provided with a pressure reducing exhaust port 42 having a pressure reducing valve 40 interposed therebetween.
The substrate 2 is held on the substrate holding plate 3 by a vacuum chuck method. Further, in the small chamber 28 of the stamper holding block 26,
The pressurized air port 46 provided with the pressurizing valve 44 is connected, and the stamper holding block 26 is raised together with the stamper 10 while supplying the pressurized gas into the small chamber 28, and the peeling operation is completed. According to this method, the dust left on the stamper surface and the signal transfer surface of the substrate is blown by the compressed air simultaneously with the peeling, and it is possible to remove the dust. In the above embodiment, the peeling is started from the inner peripheral end of the ring-shaped radiation curable resin, but the invention is not limited to this, and the peeling may be started from the outer peripheral end.

Further, in the above-mentioned embodiment, the example in which the radiation curable resin is provided on only one side of the substrate has been shown, but the present invention is not limited to this, and for example, for the purpose of increasing the surface hardness or reducing the warp, the both sides are covered. It can also be applied to the case of having a resin. Further, although the radiation curable resin is cured by using ultraviolet rays as the radiation, it is not limited to this, and other radiation such as infrared rays or electron beams may be used depending on the properties of the cured resin.

[0022]

As described above, according to the present invention,
The following excellent operational effects can be exhibited. The semi-cured state of the radiation curable resin can be controlled so that the contact force between the contact surface of the stamper and the stamper has a predetermined distribution. Therefore, the adhesive force at the end of the contact surface between the stamper and the radiation curable resin is reduced. In addition, it is possible to prevent a sudden change in the adhesive force within the contact surface. Therefore, the peeling can be easily started and the movement of the peeling point can be smoothly performed, so that the peeling operation can be shortened, the productivity can be improved, and the resin residue on the stamper can be extremely reduced. The amount can be reduced and the yield can be improved.

[Brief description of drawings]

FIG. 1 is an explanatory diagram for explaining a method of copying an optical disc according to the present invention.

FIG. 2 is a distribution chart showing the transmittance of radiation.

FIG. 3 is a diagram showing a modified example when the radiation curable resin is semi-cured.

FIG. 4 is a view showing a rotating disk used when semi-curing a radiation curable resin.

FIG. 5 is a cross-sectional view showing an example of a device when performing a transfer peeling operation.

FIG. 6 is a cross-sectional view showing another device example when performing a transfer peeling operation.

[Explanation of symbols]

2 ... Substrate, 3 ... Substrate holding plate, 4 ... Center hole, 5 ... Metal film,
6 ... Radiation curable resin, 8 and 8b ... Radiation (ultraviolet), 1
0 ... Stamper, 12 ... Pit, 14 ... Transfer surface, 16 ... Optical disc, 26 ... Stamper holding block.

Claims (1)

Claim: What is claimed is: 1. A method of replicating an optical disk by press-bonding a stamper to a radiation-curable resin formed on a substrate, which comprises: In order to facilitate the separation of the stamper and the radiation curable resin, the radiation curable resin is irradiated with radiation so as to have a predetermined distribution of the radiation irradiation amount in the region where the radiation curable resin is formed, and the radiation curable resin is in a semi-cured state. A method of duplicating an optical disc, comprising: