JPH0573968A - Method and device for forming optical disk substrate - Google Patents

Abstract

PURPOSE:To obviate the formation of defects on the rear surface of a stamper and fine ruggedness on the front surface of the stamper. CONSTITUTION:A photosensitive resin 2 is inserted between a a base plate 3 and the stamper 1. A stamper base 8 consists of a mounting base 4, a double- coated adhesive tape 5, an elastic material 6, and a vinyl sheet 7. Since the elastic material 6 is disposed on the rear surface of the stamper 1, the uniform disk substrate is formed even if there are the unequal thickness of the stamper, the projecting parts of the rear surface of the stamper, etc.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to an optical disk substrate molding method and molding apparatus.

[0002]

2. Description of the Related Art Generally, an optical disk is manufactured by forming a plastic substrate by a 2P (Photo-polymer) method or the like and applying a recording material on the plastic substrate.
As the speed increases, the demands on the flatness of the substrate have become stricter. In order to solve such a situation, Japanese Patent Laid-Open No. 2-126434 discloses, for example, a device for preventing air bubbles from being entrapped between the stamper and the ultraviolet curable resin. In this publication, a rubber bag is arranged on the back surface of the stamper, and gas or liquid is injected into the rubber bag and pressurized to press the stamper in a convex shape. The Japanese Patent Publication No. 3-5975 uses a pressing body having a spherical convex structure whose surface is elastically deformable. In Japanese Patent Laid-Open No. 2-113456, a stamper is formed of a curved elastic body whose recording both sides are convex. Further, in JP-A-59-9012, the back surface of the stamper is backed and reinforced.

There are injection molding method, compression molding method, injection compression molding method, photosensitive resin method (Photo-polymer method, 2P method) and the like as methods for producing a disk substrate using a stamper. It is a popular method, and is a method of injecting and molding a disk material into a mold equipped with a stamper. The molding cycle is short and the productivity is excellent, but the transferability is poor.
In the compression molding method, the material is plasticized by an extruder, then preformed, then put into a mold, and it is compressed to form a disk, which has better transferability than the injection molding method, but the cycle time is longer. It becomes long and the production efficiency is poor.

Like the injection molding method, the injection compression molding method comprises an injection device and a mold clamping device. After the mold is closed once,
When injection is performed without clamping, the injection pressure causes the mold to open by a predetermined size. After that, the mold is clamped, and the resin in the mold cavity is spread and formed by the pressure of the mold clamping. Although this can be said to be a further improved method as compared with the compression molding method, it has drawbacks that the cycle time is longer and the stamper life is shorter than the injection molding method. What is common to these three methods is that the equipment cost is high, a large space and a large amount of power are required, and the efficiency of intermittent use becomes extremely poor compared to continuous use. Is there.

The 2P method is a method of manufacturing a disk substrate using a resin that is cured by ultraviolet irradiation, and not only excels in transferability of fine irregularities of a stamper,
The feature is that the disk can be produced with simple equipment whenever necessary. Therefore, the 2P method is used not only for the production of disk substrates, but also for checking the stamper when the disk substrates are mass-produced using the above methods. However, as in the conventional method, there is not only a defect that air bubbles are easily trapped, but also a defect that defects on the back surface of the stamper are formed as fine irregularities on the stamper surface and are transferred to the disk substrate. There is also a method of lining the stamper, but once it is lining, it has the drawback that it cannot be used except for the 2P method.

FIGS. 6 (a) to 6 (j) are views showing a conventional method for manufacturing a disk master (stamper), in which 11 is a glass disk, 12 is a photoresist adhesive, 13 is a photoresist, and 14 is a photoresist. Is a latent image, 15 is unevenness, 16 is a conductive surface, 17 is nickel electroforming, and 18 is a stamper. A glass disk 11 is prepared, and after the surface is polished and washed, a photoresist adhesive 12 and a photoresist 13 are applied by spin coating, and laser cutting is performed by a conventional method to form a latent image 14. Next, the irradiated portion of the laser beam is dissolved and removed by development to form minute irregularities 15. After that, the surface 16 is made conductive and electroforming 17 is performed to a predetermined thickness. The electroformed plate is peeled off from the glass disk 11, and the adhesive 12 and the photoresist 13 remaining on the surface are washed and removed to obtain a stamper 18. When lining the stamper 18,
A backing stamper can be obtained by adhering the backing plate to the electroformed plate in a state where the electroformed plate is attached to the glass disc 11 and then peeling the backing plate from the glass disc 11.

7 (a) to 7 (d) are diagrams showing a conventional disk substrate manufacturing process by the 2P method, FIG. 7 (a) is a diagram showing preparation of a mold and a base plate, and FIG. FIG. 6C is a diagram showing filling with a functional resin, FIG. 8C is a diagram showing curing by ultraviolet rays, and FIG. In the figure, 21 is a mold (nickel stamper), 22 is a photosensitive resin, 22a is a cured photosensitive resin, 23 is a base plate, and 24 is a completed disk substrate. First, stamper 2
2P resin 22 is applied on 1, and the base plate 23 is placed on it. Then, pressure is applied from above the base plate 23 to spread the 2P resin 23 between the stamper 21 and the base plate 23. Next, ultraviolet rays are radiated through the base plate 23 to cure the 2P resin 22. Two
After the P resin 22 is hardened, the base plate 23 and the hardened 2P resin 22a are separated from the stamper 21 to obtain the disk substrate 24.

However, not only the stamper 21 has a non-uniform thickness, but the back surface of the stamper is rough,
According to the 2P method, it has been confirmed that the obtained disk substrate has unevenness in thickness and minute unevenness. A method of bending the stamper using a rubber bag has been proposed for the purpose of preventing air bubbles from being entrapped, but it is not preferable because the stamper may be deformed.

FIGS. 8 (a) and 8 (b) are views showing a stamper mounting base, in which 25 is a magnet, 26 is a mounting base, 27 is a groove for a vacuum chuck, and other functions similar to those in FIG. The same reference numerals are given to the parts to be applied. In FIG. 7, the method of manufacturing the disk substrate by the 2P method has been described, but actually, when manufacturing the 2P disk substrate, a table for fixing the stamper in some form is required. FIG. 8A shows a method of fixing the stamper by using the magnet 25, and FIG. 8B shows a configuration diagram of the method of fixing the stamper by the vacuum chuck 27, but a mechanical holding method or the like is also conceivable. However, in any case, the stamper fixing base is made hard assuming that pressure is applied from above the base plate.

[0010]

[Object] The present invention has been made in view of the above-mentioned circumstances, and when manufacturing a disk substrate from a stamper by the 2P method, a method of not forming defects on the back surface of the stamper or fine irregularities on the stamper surface, that is, 2P The object of the present invention is to provide a disk substrate molding method and a molding apparatus by a method in which only the unevenness on the surface of the stamper is transferred by 2P without transferring it to a transfer disk.

[0011]

In order to achieve the above object, the present invention provides (1)
By inserting the ultraviolet curable resin between the transparent substrate and the stamper and pressing them against each other, the ultraviolet curable resin is spread to a predetermined size and irradiated with ultraviolet rays, and the stamper is cured by curing the ultraviolet curable resin. In the optical disk substrate molding method of molding the optical disk substrate by transferring the concavities and convexities of (1) to the ultraviolet curable resin on the transparent substrate, an elastic body is arranged on the back surface of the stamper, and (2) the elastic body is sponge, Using a material having water absorbency such as cloth, non-woven fabric, cotton, paper, and further, (3) above (2)
In (4), the elastic body is made to absorb a fluid such as water, oil, gel, and (4) In (1), an air bag is used as the elastic body. In 4), the air bag is filled with a gas, and (6) In (5), the gas in the air bag is an inert gas such as nitrogen, argon, or helium. Further, (7) In (4), the fluid is enclosed in the air bag.
Further, (8) in (7), the fluid is water,
Encapsulating liquid such as oil, or (9) stamper,
A base plate provided on the stamper, a photo-curable resin filled between the stamper and the base plate, a mounting base for holding the stamper, and an elastic body provided between the mounting base and the stamper. It consists of and. Hereinafter, description will be given based on examples of the present invention.

FIG. 1 is a block diagram for explaining an embodiment of an optical disk substrate molding method according to the present invention, in which 1 is a mold (nickel stamper), 2 is a photosensitive resin (liquid),
3 is a base plate, 4 is a stamper mount, 5 is double-sided adhesive tape, 6 is sponge, 7 is a vinyl sheet, and 8 is a stamper stand. In the present invention, the stamper mount 4
It is characterized in that the elastic body 6 is interposed between the stamper 1 and the stamper 1. That is, the double-sided adhesive tape 5 is put on the stamper mount 4, an elastic body (sponge 6 in the figure) larger than the stamper is arranged in the substantially central portion thereof, a vinyl sheet 7 is covered as necessary, and the stamper 1 is placed thereon. To place. In the following, the 2P disk substrate may be manufactured by the method as described above.

The stamper is manufactured according to the standard method (example of FIG. 4).
Use the one that you made. Below are the main steps in the stamper manufacturing process.
The conditions and materials are shown. (1) Glass disk φ250mm x 6mmt (2) Photoresist adhesive Hexamethylene disilaza
(3) Photoresist positive type (Tokyo Ohka's OF
RP-800) (4) Developer Alkaline developer (Tokyo Oh
DE-3) (5) Surface electrification Nickel stamper approx.
500Å Thickness (6) Electroforming Nickel electroforming Bath composition Nickel sulfamate 450g / l Nickel bromide 5g / l Boric acid 30g / l Bath temperature 50 ℃ ph4.0 Current density 0-60A / cm²  Thickness 0.3mm In this way, the stamper is made of nickel about 0.3mm thick.
To obtain a flat plate (the size can be freely processed
I).

The stamper mount 4 in FIG. 1 may be made of aluminum, iron, plastic, or any other solid material.
Aluminum is suitable in consideration of workability and weight.
This stamper mount is preferably 20 mm to 100 mm larger in diameter than the stamper. The thickness is not particularly limited, but 10 mm to 20 mm is easy to handle. The double-sided adhesive tape 5 is applied on the stamper mount, and the sponge 6 is attached to the center of the stamper mount in a shape larger than the stamper size and smaller than the stamper mount size. The sponge 6 also has no particular limitation on the thickness, but 3 mm to 10 mm is easy to use. Then, the vinyl sheet 7 is attached so as to cover the sponge 6. This vinyl sheet 7 is not always necessary, but since the stamper is made of nickel and the sponge 6 is soft, the sponge easily breaks when they are brought into contact with each other. .2mm) 7 should be attached. Place the stamper on the stamper base 8 assembled in this way,
In the following, a 2P disk substrate is manufactured according to a conventional method.

FIGS. 2 (a) and 2 (b) are views showing a comparison of the thickness of the 2P layer according to the method of the present invention and the conventional method using the same stamper. FIG. 2 (a) shows the conventional method. Figure (b) is the method of the present invention. According to the conventional method, the thickness unevenness was 0.05 mm, but with the method of the present invention, it was 0.02 mm or less.
The sponge used in the method of the present invention has a thickness of 2 mm and a size of φ.
A 230 mm thick sheet was used with water and covered with a 0.2 mm thick vinyl sheet. In the method of the present invention, the sponge was taken as the elastic body for explanation.
Materials such as cotton, cloth, paper and non-woven fabric can be used. Also, good results can be obtained by using a fluid such as water or oil absorbed in these materials.

FIG. 3 is a view showing another embodiment of the disk substrate molding method according to the present invention, in which 9 is an air bag,
Reference numeral 10 is a stamper base, and other parts having the same functions as those in FIG. 1 are designated by the same reference numerals. The basic structure is the same as that shown in FIG. 1, except that an air bag 9 is used instead of the sponge. Although the air bag 9 is used in FIG. 3, not only the air bag 9 is necessarily used in the air bag 9, but a bag in which other gas bodies such as nitrogen gas and argon gas are enclosed can also be used. It's obvious. Further, according to experiments, similar results were obtained even when a fluid (water, oil, gel, etc.) was enclosed in the air bag. The variation of the 2P layer when water was enclosed was 0.05 mm in the conventional method, but was 0.0 in the method of the present invention.
It became less than 015 mm. Further, if there is a convex portion generated on the back surface of the stamper during electroforming, the 2P layer is thinned by the conventional method, but it has been found that the 2P layer of a uniform thickness can be obtained by the method of the present invention. ..

FIGS. 4 (a) to 4 (c) are 2P's of a conventional method in which the back surface of the stamper has a convex portion and a method according to the present invention.
It is a figure which shows the comparison of the thickness of a layer, Drawing (a) is a convex part of the back of a stamper, Drawing (b) is a conventional method, Drawing (c) is a method of the present invention. This is because if the stamper base is hard, the convex portion on the back surface of the stamper 1 cannot be absorbed, and when the base plate 3 is pressed in the 2P transfer process, the surface of the stamper 1 becomes convex and is directly transferred to the 2P layer. As shown in FIG. 2B, the shape of the stamper 1 is the same as that of the conventional method.
If the back surface of the stamper is in contact with an elastic body that is a soft material, the stamper 1
The convex portion on the back surface of the stamper penetrates into the elastic body, and even if the base plate 3 is pressed in the 2P transfer process, the surface of the stamper 1 remains flat.
There is no effect on the back side of. This not only absorbs the convex shape on the back surface of the stamper 1 generated in the stamper manufacturing process,
The same effect is obtained when a foreign substance such as dust is inserted between the stamper 1 and the stamper base in the 2P transfer process.

FIG. 5 is a view showing still another embodiment of the disc substrate molding method according to the present invention, in which 11 is a frame and 12 is a frame.
Is a rubber bag, 13 is a fluid, and other parts having the same functions as those in FIG. 3 are denoted by the same reference numerals. In the embodiment shown in FIG. 5, the pressurizing side also has elasticity. By filling the rubber bag 12 with the fluid 13 and putting it in the frame 11 to pressurize and depressurize the fluid 13. , Base plate 3
By making the pressure applied to the base plate uniform so that the pressure applied to the entire surface of the base plate becomes uniform, the pressure applied to the stamper 1 through the base plate 3, 2P layer becomes uniform, and uneven thickness is less likely to occur.

[0019]

[Effect] As is apparent from the above description, the present invention has the following effects. (1) In the disk substrate molding method, since the elastic body is arranged on the back surface of the stamper, a uniform disk substrate can be formed even if there is unevenness in the thickness of the stamper or a protrusion on the back surface of the stamper. 5). (2) Handling is easy because a soft absorbent material is used (corresponding to claim 2). (3) Since the elastic body absorbs the fluid, the effect is greater than when the fluid is not absorbed (corresponding to claim 3). (4) Workability is good because an air bag is used as the elastic body (corresponding to claim 4). (5) Workability is good because gas is enclosed in the air bag. (6) The safety is high because an inert gas is used as the gas. (7) The effect is great because the fluid is enclosed in the air bag. (8) Since liquid is used as the fluid, workability and effect are well balanced.

[Brief description of drawings]

FIG. 1 is a configuration diagram for explaining an embodiment of a disc substrate molding method according to the present invention.

FIG. 2 is a diagram showing a comparison of the thickness of the 2P layer according to the method of the present invention and the conventional method using the same stamper.

FIG. 3 is a diagram showing another embodiment of the disc substrate molding method according to the present invention.

FIG. 4 is a conventional method when there is a convex portion on the back surface of the stamper,
FIG. 5 shows a comparison of the thickness of the 2P layer with the method according to the invention.

FIG. 5 is a view showing still another embodiment of the disc substrate molding method according to the present invention.

FIG. 6 is a diagram showing a method of manufacturing a conventional disk master (stamper).

FIG. 7 is a diagram showing a disk substrate manufacturing process by a conventional 2P method.

FIG. 8 is a diagram showing a stamper mount.

[Explanation of symbols]

1 ... Mold (nickel stamper), 2 ... Photosensitive resin (liquid), 3 ... Base plate, 4 ... Stamper mount, 5 ...
Double-sided adhesive tape, 6 ... sponge, 7 ... vinyl sheet,
8 ... Stamper stand.

Claims (5)

[Claims] 1. An ultraviolet curable resin is inserted between a transparent substrate and a stamper and pressed against each other to spread the ultraviolet curable resin to a predetermined size and perform ultraviolet irradiation.
In the optical disk substrate molding method of molding the optical disk substrate by transferring the unevenness of the stamper to the ultraviolet curable resin on the transparent substrate by curing the ultraviolet curable resin, an elastic body is arranged on the back surface of the stamper, and the back surface of the stamper is arranged. A method for forming an optical disk substrate, characterized in that the convex portion of the optical disk is embedded in the elastic body. 2. The sponge, cloth, and
2. The method for molding an optical disk substrate according to claim 1, wherein a material having a water absorbing property such as non-woven fabric, cotton or paper is used. 3. The optical disk substrate molding method according to claim 2, wherein the elastic body is made to absorb a fluid such as water, oil or gel. 4. The optical disk substrate molding method according to claim 1, wherein an air bag is used as the elastic body. 5. A stamper, a base plate provided on the stamper, a photo-curable resin filled between the stamper and the base plate, a mount for holding the stamper, the mount and the stamper. And an elastic body provided between the optical disk substrate molding apparatus and the optical disk substrate molding apparatus.