JPH0729219A - Production of optical disk - Google Patents

Abstract

PURPOSE:To mass-produce optical disks only for reproduction such as CD-ROM at a low cost in a short time. CONSTITUTION:An information pattern on a master is transferred to a transparent substrate of plastic, etc., by a 2P method using a UV-curing resin to produce a replicated master 8. Many such replicated masters 8 are two-dimensionally arranged on a plate 9 of plastic, etc., fixed and plated with Ni to produce an Ni stamper having many information patterns by a single plating process. This Ni stamper is fed into an injection molding machine and a substrate having many information patterns is molded by a single molding process, or the many information patterns of the Ni stamper are cut into Ni stampers, these stampers are fed into an injection molding machine and optical disk substrates are simultaneously produced.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of manufacturing a read-only type optical disk such as a CD-ROM, and more particularly to a method of manufacturing an information pattern transfer stamper and a substrate molding method using the stamper.

[0002]

2. Description of the Related Art Optical discs include a read-only type and a readable / writable type. The former includes a laser disk (LD) and a compact disk (CD), which are currently mass-produced. In addition to these, there are CD-ROMs, CD-Is, etc. as multimedia media in the read-only disc
These are now undergoing great development. In particular, there are great expectations for CD-ROMs as electronic publications. Current,
CD-ROMs are used in dictionaries, navigation maps, telephone directories, patent specifications, teaching materials, encyclopedias, game software, and the like. Furthermore, it is expected that it will be applied to fields such as newspapers and weekly magazines that require immediacy and a large number of copies. Compared to conventional paper, the weight and volume per information volume will be much smaller, which should be advantageous in terms of forest resources and waste. In addition, the plastic material of the optical disc has a high possibility of being recycled.

The manufacturing process of a read-only optical disc according to the prior art is as follows. First, a positive photoresist is applied on a glass substrate. The photoresist film is irradiated with a laser beam modulated in accordance with information. This is called the cutting process. When this is developed, the light irradiation portion is dissolved and removed, and information is formed in the photoresist film as concave pits. This is called the master.

Next, a conductive film such as Ni is provided on the photoresist film of the master by a sputtering method, a vapor deposition method or an electroless plating method. Using this conductive film as an electrode, a Ni layer having a thickness of about 300 μm is formed by a plating method. This plating takes a long time of 3 to 6 hours. Moreover, only one can be done. Ni
Peel the layers from the master. At this time, the photoresist is N
When it remains on the surface of the i layer, it is removed by plasma ashing of oxygen. The outer periphery of this Ni layer is processed to form a Ni stamper.

In such a process, only one Ni stamper can be obtained from one master. Also this 1
The second Ni stamper is plated once again and the second N
You can make an i stamper. The information pit on the surface of the second stamper is concave. When injection molding is performed using a concave pit stamper, it is difficult for the melted material of plastic, which is the optical disk substrate material, to enter the concave pits.
Therefore, there is a problem that a substrate having information pits with a predetermined depth cannot be formed. However, if a third stamper is formed from this second stamper by a plating method, a stamper having convex pits can be obtained, and normal injection molding can be performed.

There are two methods for molding a substrate using the obtained Ni stamper. One is the above-mentioned injection molding method, and the second is the 2P method using an ultraviolet curable resin. Currently, CDs, CD-ROMs, and LDs are manufactured by the injection molding method. In this method, molten polycarbonate is filled at high pressure in a mold equipped with a Ni stamper, then cooled and taken out. It takes about 10 seconds to cool the resin at about 350 ° C to about 80 ° C. A reflective film of Al or the like is provided on the surface of the thus formed substrate having the information pits.
An optical disk is completed by forming a protective film using an ultraviolet curable resin on the surface of this Al film.

On the other hand, in order to apply the CD-ROM to newspapers and weekly magazines, it is necessary to manufacture stampers and replicas at a speed comparable to that of the current printing technology. However, in the conventional technique, the manufacturing speed is too slow as described above, and it is not possible to respond to this. Specifically, as soon as the original information is obtained from the user, a master is made. Next, the first Ni stamper is manufactured by the plating method. This first Ni stamper is a convex pit and can be used as it is for injection molding. However, with only one stamper,
Since the injection molding speed is low, it is not possible to make a large number of sheets.

Therefore, a large number of Ni stampers are produced and replica substrates are produced by a plurality of injection molding machines. There are two ways to do that. One is a method in which cutting of the same information is repeated to produce a large number of masters and Ni stampers are made from the individual masters. The second is 1.
This is a method of making a large number of stampers by plating a large number of Ni stampers.

In the former case, 30 times are required for one cutting process.
It takes as long as -60 minutes and the produced master is strictly inspected, so its yield is limited. Further, the cutting device is very expensive, and it is inefficient to spend a long time on only one piece of information. On the other hand, in the second method, if plating is repeated, the number of stampers obtained will increase by a factor of two. However, in this case, half of the stampers are concave pits and cannot be applied to the injection molding device. Moreover, 3 ~ for plating
It takes 6 hours. That is, it takes too much time to make a large number of Ni stampers, and it is not possible to satisfy the demand for immediacy.

Further, at the conventional injection molding speed, even if the stamper can be formed for a short time, it is not possible to satisfy the requirements of immediacy and a large number of copies.

[0011]

SUMMARY OF THE INVENTION The present invention solves the above-mentioned drawbacks of the prior art and provides a method for producing a large number of read-only optical disks in a short time.

[0012]

Means for Solving the Problems An information pattern on the master is transferred from a master to a plastic or glass substrate by a 2P (Photopolymerization) method using an ultraviolet curable resin (UV resin). This transferred substrate will be called a replica master. This process can transfer in a short time, and more than one transfer can be performed from one master. A large number of replica masters thus obtained are two-dimensionally arranged and fixed on a plate made of plastic or the like. After providing a metal thin film of Ni or the like on this, Ni plating is performed. Thus, one Ni stamper having many information patterns is manufactured by one plating process. This Ni stamper is applied to an injection molding device to mold a substrate having a large number of information patterns by one molding process. Further, a large number of information patterns are separated into Ni stampers one by one, and each is subjected to an injection molding apparatus to simultaneously manufacture optical disk substrates.

[0013]

[Function] A large number of Ni sheets can be produced from one master in a short time.
Since a stamper can be obtained and a large number of substrates can be made at once by one injection molding process, CD-ROM
Can be manufactured at high speed and at low cost.

[0014]

EXAMPLE As shown in FIG. 1A, a negative photoresist 2 is applied on a glass substrate 1 to a thickness of 0.1 to 0.2 μm. This is applied to a cutting device to irradiate the laser beam 3 modulated according to information. When this is developed, as shown in FIG. 1 (b), a convex mark 4 is obtained where the light is irradiated.

As the negative type resist, a positive type image reversal resist can be used. This is a positive resist from the beginning, but it is a negative resist when it is subjected to a heat treatment after exposure (reversal bake) and then developed.

On top of this, as a release film, Ti, Al, Al
-A film of Ti alloy or the like is formed by a sputtering method or the like. A liquid UV resin 5 is placed thereon, and a plastic or glass plate 7 that transmits UV light is pressed from above to spread the UV resin. Next, UV from the transparent plate 7 side
After irradiating light to cure the resin, the release film and the cured U
When peeled from the V resin layer, a replica master having information marks transferred thereon is obtained as shown in FIG. In this case, the information mark 6 is concave. By repeating such transfer with the UV resin, it is possible to make several tens of replica masters from one master.

Next, as shown in FIG. 1D, these replica masters 8 are attached to a plate 9 made of plastic, glass or the like. The plate 9 is preliminarily formed with a recess into which the replica master is exactly inserted. If there is a gap between the replica substrate and the recess, it is filled with an adhesive or the like to be flat. A thin film of Ni or the like is provided on this. For this, an electroless plating method, a sputtering method, or a vapor deposition method can be used. Next, this is immersed in a nickel sulfamate aqueous solution and plating is performed until the thickness of the Ni layer becomes approximately 300 μm.

Then, the Ni plating layer is peeled off from the plate 9. The information pit of the stamper thus obtained has a convex shape suitable for injection molding. A large number of CD-ROM patterns having the same information are formed on one nickel plate. If this is set as it is in the injection molding device, a large number of patterns can be transferred by one molding. A reflective film of Al or the like is provided on the surface of the molded plastic plate by a sputtering method or the like. Further, a thin plastic film is adhered on it as a protective film. Next, the center of the concentric or spiral pattern is detected, and the inner and outer peripheries are mechanically punched to make the CD-R.
The OM disc is completed. Alternatively, the disc may be formed by punching at the stage of the injection-molded plate and then forming the reflection film and the protective film.

In making a master, as shown in FIG. 2, a positive type photoresist 10 is used instead of the negative type photoresist.
Can also be used. In this case, as shown in FIG. 2C, first, a first replica master is made from the master. The recording mark 11 has a convex shape, and if Ni plating is performed as it is, it becomes a concave stamper and is not suitable for injection molding. Therefore, as shown in FIG.
Take the first replica master and send it to the next plating process. After that, the optical disc can be manufactured by the same method as described above.

On the other hand, a replica master can also be produced by the method shown in FIG. First, a recording film 13 whose transmittance is reduced by a laser beam is provided on a circular substrate 12 made of glass or transparent plastic. As this recording film, for example, a chalcogenide film or a dye film in which fine holes are formed by a laser beam can be used. Further, if a guide groove for tracking the laser beam is formed between the substrate 12 and the recording film 13, an expensive cutting device is not required, and information is recorded by a commercially available inexpensive optical disk device. be able to. The guide groove is 2P using UV resin in case of glass substrate
Method, or in the case of a plastic substrate, an injection molding method.

A hole 14 is formed as a recording mark of information on this substrate with a recording film, and this is used as a photomask. As shown in FIG. 3C, the photomask is brought into close contact with the negative photoresist 2 coated on the glass substrate 1 and exposed to UV light. If this is developed,
As shown in (d), the recording mark 4 has a convex shape. From now on 2
A replica master (e) is obtained by the P method. The Ni stamper is made from this as described above. When a positive photoresist is used instead of the negative photoresist, a convex stamper can be obtained by taking the replica master twice as shown in FIG.

The present technique can be applied not only to the read-only type optical disc as described above, but also to the production of a write-once type or reversible type optical disc substrate.

(Example 1) As a negative resist 2, a positive image reversal photoresist AZ-5200E was spin-coated to a thickness of 0.11 μm on a glass substrate 1 having a thickness of 10 mm, and then at 80 ° C. for 1 hour. I baked. This was applied to a cutting device equipped with an Ar ion laser beam, and
As shown in (a), the laser light beam 3 modulated according to information is irradiated. The recording marks were recorded spirally and the track pitch was set to 1.6 μm. Next, this is 12
After heat treatment (reversal bake) at 0 ° C. for 5 minutes, uniform exposure over the entire surface was performed, and then development processing was performed. In this case, the recording mark 4 irradiated with light is formed in a convex shape as if it were a negative type.

After this was post-baked, a Ti release layer was formed to a thickness of 50 nm by a sputtering device. Acrylic liquid UV resin 5 on the surface of this Ti film
Then, a disk-shaped PMMA (acrylic) substrate 7 having a thickness of 2 mm is pressed from above to spread the UV resin. UV light was irradiated from the acrylic substrate side to cure the UV resin. Next, the Ti film and the UV resin layer are separated from each other, and a replica master as shown in FIG. 1C is completed. By repeating this UV resin process, seven replica masters were produced.

Next, as shown in FIG. 1 (d), a thickness of 5
A recess for accommodating the replica master 8 was made in the PMMA plate 9 of mm, and the replica master was adhered therein. The gap was also filled with an adhesive to make it flat. A Ni film having a thickness of 60 nm was provided on this by a sputtering method.

Next, this was immersed in a nickel sulfamate bath and a Ni layer having a thickness of about 300 μm was plated. UV
By peeling between the resin layer and the Ni layer, a Ni stamper having seven information patterns could be obtained. The information mark of this stamper has a convex shape suitable for injection molding. This stamper was set in an injection molding device, and a substrate was molded using polycarbonate.

This polycarbonate substrate having seven information patterns was continuously passed through a sputtering apparatus to form an Al reflection film having a thickness of about 60 nm. Next, on the Al film, a 100 μm-thick plastic film with an adhesive was adhered. Finally, the center of each information pattern was detected by optical means, and punched out as a 3.5-inch CD-ROM. At this time, center detection was performed with one pattern, and punching was performed on seven sheets at the same time.

The electrical signal characteristics of the obtained CD-ROM are as follows:
It was equivalent to a conventional CD-ROM. In addition, write-once and reversible optical disk substrates were also manufactured by this process. In this case, instead of the reflective film of Al, each Te
System hole forming type recording film, GeSbTe phase change recording film, TbF
When an eCo magneto-optical recording film or the like was laminated and evaluated, it was confirmed that the substrate was a good quality.

(Embodiment 2) This will be described with reference to FIG. First, a polycarbonate substrate 12 having a diameter of 3.5 inches and a thickness of 1.2 mm was prepared. On this substrate, a guide groove having a track pitch of 1.6 μm, a width of 0.5 μm and a depth of 0.08 μm is spirally formed. As a base film on this substrate,
An F-based polymer film having a thickness of about 40 nm was formed by the sputtering method (not shown in the figure).

Next, as the recording film 13 on the surface of the base film,
TeSePb having a thickness of about 25 nm was also laminated by sputtering. Information was recorded by applying this to a commercially available write-once optical disc device. As shown in FIG. 3B, it is recorded as a fine hole 14, and the reflectance at the hole is reduced. This recorded substrate is used as a photomask. On the other hand, as a negative resist 2, a positive image reversal photoresist was applied to a thickness of 0.11 μm on a glass substrate 1 having a thickness of 2 mm. Next, as shown in FIG. 3C, the resist film was brought into close contact with the recording film side of the photomask, and UV light 15 was exposed. When this is reversal baked and then developed, the recording marks 4 are convex as shown in FIG. However, in this case, the guide groove is not transferred. This is because the groove is covered with the recording film and does not transmit UV light. This is shown in FIG.
This corresponds to the master shown in (b). After that, a CD-ROM was manufactured by the same process as in Example 1.

The electric signal characteristics of the obtained CD-ROM are as follows:
It was equivalent to a conventional CD-ROM.

[0032]

[Effects of the Invention] By performing Ni plating on a plurality of replica masters, producing a Ni stamper having a plurality of information patterns, and performing injection molding, a plurality of optical disk substrates can be produced in a single process. As a result, the CD
-The ROM can be applied to newspapers, weekly magazines, magazines, etc. that require immediacy and mass production.

[Brief description of drawings]

FIG. 1 is an explanatory view of a replica master and stamper manufacturing process according to the present invention.

FIG. 2 is an explanatory view of a second manufacturing process of a replica master according to the present invention.

FIG. 3 is an explanatory view of a third manufacturing process of a replica master according to the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Glass substrate, 2 ... Negative photoresist, 3 ... Laser light beam, 4 ... Convex recording mark, 5 ... UV curable resin, 6 ... Recessed recording mark, 7 ... Glass or plastic substrate, 8 ... Replica master, 9 ... a plastic plate.

Claims (3)

[Claims] 1. A photoresist is coated on a glass substrate,
A plurality of transparent substrates on which information patterns have been transferred by using an ultraviolet curable resin are arranged on a resin plate from a master obtained by irradiation with a laser light beam modulated according to information and development, and Ni is formed on the transparent substrate. A method for manufacturing an optical disk, characterized by performing injection molding using a stamper obtained by plating. 2. A recording film, the light transmittance of which is changed by light irradiation, is formed on the transparent substrate having guide grooves formed in a spiral shape or a concentric shape, and then the light beam is used to form the recording film. A method for manufacturing an optical disc, which uses a master mask obtained by exposing a recording film on which information is written to a photo mask for transfer, and bringing this into close contact with a photoresist film coated on a glass substrate. 3. The method for manufacturing an optical disc according to claim 1, wherein a release layer is provided on the surface of the master.