JPH04246188A - Method for electroforming stamper for forming optical recording medium - Google Patents

Abstract

PURPOSE:To prevent the sticking of an electroformed film 6 to a conductive ring 3 and to obtain the electroformed film uniform in thickness at the time of producing a stamper used for forming an optical recording medium by electroforming. CONSTITUTION:A conductive ring 3 with one end stretched to a specified length and at a specified angle is set between an original disk 1 and an original disk holder 2, a current is applied from the periphery of the original disk, and electroforming is carried out.

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 recording medium, and more particularly to a method for electroforming a stamper for manufacturing an optical recording medium for optically recording and reproducing information.

0002

2. Description of the Related Art Conventionally, magnetic materials such as magnetic tapes and magnetic disks, various semiconductor memories, and the like have been mainly used to record various types of information. Such magnetic memories and semiconductor memories have the advantage that information can be easily written and read, but on the other hand, they have the problem that the information content can be easily tampered with and high-density recording cannot be performed. there were. In order to solve these problems, an optical information recording method using an optical recording medium has been proposed as a means to efficiently handle a wide variety of information, and an optical information recording carrier, a recording/reproducing method, and a recording/reproducing device for this purpose have been proposed. has been done. Such optical recording media as information recording carriers generally use laser light to evaporate a part of the optical recording layer on the information recording carrier, cause a change in reflectance, or cause deformation. Information is recorded or reproduced based on differences in optical reflectance and transmittance. In this case, the optical recording layer is a so-called DRAW (Direct Read After Write) medium that does not require any development treatment after information is written and can be "directly read after writing", and is capable of high-density recording. It is also possible to write additional information, so it is effective as an information recording/storage medium. FIG. 4 is a schematic cross-sectional view of a general optical recording medium (optical disk, optical card, optical tape, etc.). Recording and reproduction of information is performed while positioning is performed using the fine irregularities of the track groove portion 22 and the phase difference of laser beams. And in such optical recording media,
The transparent substrate 21 is made of thermoplastic resin such as polycarbonate resin or polymethyl methacrylic resin, and this resin substrate is made of
A stamper on which a concavo-convex pattern corresponding to the track and information is recorded is used to transfer the concavo-convex pattern to form the groove portion 22.

As shown in FIG. 5, the general method for manufacturing this stamper is as follows: A resist or photosensitive resin layer 32 is placed on a well-polished glass plate.
After forming a concavo-convex pattern 33 of a predetermined depth thereon (FIG. 5a), a conductive film 34 is formed to make it conductive (FIG. 5b), and electroforming is performed to a predetermined thickness. An electroformed film 35 is formed to obtain a metal stamper (FIG. 5c). In the conventional electroforming method, the following is performed. That is, when performing electroforming, a baffle plate is inserted between the anode and cathode of the electroforming tank to improve the plate thickness distribution. (Unexamined Japanese Patent Publication No. 59
-177388, 60-17089, 61-279
699) To prevent pinholes, foreign matter such as insoluble oxide slime and smut generated in the electroforming tank is removed into a preliminary tank. (Utility Model Application No. 58-141435) Furthermore, the traces of the energizing jig during electroforming are sealed with ultraviolet curable resin to prevent abrasives from penetrating during polishing. (Japanese Unexamined Patent Publication No. 62-209746) However, when electroforming is performed, the conductive ring 3 on the outer circumference of the master 2 is also electroformed, as shown in part A of FIG. There is a problem that they stick together and become integrated, and when removing the conductive ring 3 after electroforming, separation occurs between the master 2 and the electroformed film 6, and the polishing liquid may seep into the master 2 during polishing. There is a problem that the electroformed film 6 may peel off. For this purpose, as mentioned above, the traces of the current-carrying jig are sometimes sealed with ultraviolet curing resin, but the areas sealed with resin swell up as shown in Figure 2B, causing problems after polishing. A problem arises in that the thickness distribution of the electroformed stamper becomes non-uniform.

0004

[Problems to be Solved by the Invention] The present invention has been made to solve the above-mentioned problems, and it is possible to create a stamper by electroforming a master disc on which a concave-convex pattern corresponding to the information to be recorded is formed. - in a method of producing
An object of the present invention is to provide a method for electroforming a stamper that prevents the electroformed film from sticking to the conductive ring, prevents the electroformed film from peeling off from the master, and has a uniform film thickness.

[0005]

[Means for Solving the Problems (and Effects)] The electroforming method of the present invention forms an optical recording medium by performing electroforming on a master disk on which a concavo-convex pattern corresponding to information to be recorded in advance on an optical recording medium is formed. In a method for manufacturing a stamper for forming a cathode, a conductive plate protruding into the electroforming liquid at a predetermined length and at a predetermined angle is placed between a master plate forming a cathode and a master plate holder holding the master plate. The method is characterized in that a ring is installed and electroforming is performed by applying electricity through the conductive ring from the outer periphery of the master.

The present inventors found that if the tip of the conductive ring 3 in contact with the master 2 is slightly separated from the master 2, the electroformed film 6 can be prevented from adhering to the conductive ring 3, and the master can be easily removed. The present invention was made based on the discovery that electroforming can be performed without peeling between the electroformed film 6 and the electroformed film 6. That is, by using the electroforming method of the present invention, by using a conductive ring having a bent portion protruding into the electroforming solution at a predetermined length and at a predetermined angle, as shown in part A of FIG. The thickness of the electroformed film on the bent portion 4 of the conductive ring 3 is reduced to prevent the electroformed film from adhering to the conductive ring, so that the electroformed film does not peel off from the master and the thick part of the electroformed film (Fig. 2B ) is advantageous in that an electroforming stamper with a uniform thickness can be obtained.

The present invention will be explained in detail below with reference to the drawings. FIG. 1 is a sectional view showing an embodiment of the stamper electroforming method of the present invention. Master disc 2 is installed in master disc holder 1, and master disc holder 1 and master disc 2 are arranged at a certain angle.
Electricity is supplied through a conductive ring 3 having a long bent portion 4. The conductive ring 3 in the manufacturing method of the present invention is
It has a bent part 4 bent at a certain length and angle. The length of the folded part 4 is determined as the electroformed film in the part below the folded part 4 is thinner than in other parts (Fig. 1).
A) Depending on the size of the master and the size of the effective area used after electroforming, it can generally be used in the range of 1 to 200 mm. Generally, the thinner part of the electroformed film is longer than the length of the bent part 4, so the length is preferably 10 to 50.
It is mm. Generally, the bending angle of the bending part 4 can be any angle as long as the thickness of the electroformed film below the bending part (FIG. 1A) can be made thinner than in other parts. However, it can be used within a range of 1 to 60 degrees. If this angle is small, a step will be created between the thinner part of the electroformed film shown in FIG. 1A and other parts. Moreover, if the angle is large, the thickness of the electroformed film tends to become non-uniform. Therefore, a more preferable angle is in the range of 10 to 45 degrees. When using a shallow angle, conductive ring 3
By making the surface of the tip of the bent portion 4 in contact with the master 2 rough, peeling of the master 2 and the electroformed film 6 can be prevented. Further, in the present invention, the shape of the bent portion 4 of the conductive ring 3 may be bent in two or more stages as required, other than the shape shown in FIG. At that time, the angle and length of each bent portion can be freely selected as long as they are within the above range.

The conductive ring 3 may be made of any material as long as it does not dissolve in the electroforming solution, but copper, stainless steel, etc. are preferable. Conductive ring 3
The length of the contact portion with the master disc 2 is 1 mm or more in order to absorb unevenness in the thickness of the master disc 2 and conduct electricity. More preferably, it is in the range of 3 to 10 mm. Similarly, the length of the contact portion between the conductive ring 3 and the master holder 1 is 1 mm or more. In order to prevent the electroforming liquid from entering from the end face of the master holder 1, it is preferable that the conductive ring 3 extends up to the end face of the master holder 1. Next, the method of electroforming is shown in Figure 3.
To explain using , after the conductive ring 3 is installed on the master disc 2 and the master disc holder 1, it is firmly fixed with the upper cover 5. It is necessary that the electroforming liquid does not mix between the conductive ring 3 and the master 2. A cathode 11 consisting of a master disc holder 1 on which a master disc 2 and a conductive ring 3 are installed is placed in an electroforming bath 13 at a position opposite to an anode 12. The cathode 11 is rotated about a shaft by a motor 14 while facing downward. The effect of the bent portion 4 of the conductive ring 3 differs somewhat depending on the rotation speed. For this reason, the preferred rotation speed is 20 to 15
It is 0 rpm. The current value can be selected within a range that does not cause warping or stress in the electroformed film. The effect of the bent portion 4 of the conductive ring 3 differs somewhat depending on the current value. Generally 200-2000A/m2, preferably 3
It can be used in the range of 00 to 800 A/m2.

[0009]

[Function] The electroforming stamper of the present invention performs electroforming using a conductive ring having a bent portion at a predetermined angle and length, so that the thickness of the electroformed film below the bent portion is thinned. This prevents the electroformed film from adhering to the conductive ring and allows the electroformed stamper to be created without peeling of the electroformed film from the master.
It provides: In addition, since the conductive ring is conductive, the electroformed film adheres to the tip of the folded part, which prevents the electroformed film from swelling on the master outside the folded part of the conductive ring, resulting in a uniform thickness. An electroforming stamper is provided.

0010

[Examples] Hereinafter, the present invention will be explained in more detail with reference to Examples, but the present invention is not limited thereto.

Example 1 Glass plate with a thickness of 10 mm and a diameter of 355 mm (Asahi Glass Co., Ltd.)
A photoresist (AZ1300, Hoechst Japan) was applied to a thickness of 0.11 μm on a photoresist (manufactured by Matsushita Electric Co., Ltd.), and a pattern was exposed and developed using a laser exposure machine (manufactured by Matsushita Electric Co., Ltd.).
A concentric concavo-convex pattern with a pitch of 1.6 μm, a width of 0.7 μm, and a depth of 1100 Å was formed. Thereafter, nickel was sputtered to a thickness of 1000 Å to make it conductive, thereby obtaining a glass master disk. Copper with a thickness of 0.5 mm and an outer diameter of 400 m
It was cut into a donut shape with an inner diameter of 325 mm, and both sides were polished with sandpaper until it became a mirror surface. The inner 10 mm of this conductive ring was bent at 35 degrees to form a bent portion. The glass master disk on which the uneven pattern was formed was placed in a master disk holder having an outer diameter of 40.0 mm. Then, the conductive ring was brought into contact with the master at an outer circumference of 5 mm, and a lid having an outer diameter of 400 mm and an inner diameter of 345 mm was placed and firmly fixed. The anode used was a nickel ball placed in a titanium cage and covered with cotton cloth to prevent waste from washing away. As the electroforming solution, use 500 liters of a solution mixed with the following composition, and prepare an electroforming tank of 150 liters and a preliminary tank of 350 liters.
Place the entire liquid in an electroforming tank and heat it 10 times at a liquid temperature of 45°C.
circulated through the cycle of time.

Nickel sulfamate (tetrahydrate) 450g/l
Boric acid
30g/l anti-pitting agent
5ml
/l current condition is to first flow 3A for 30 minutes, then 50
Raise the current to A (current density 530A/m2), 13
Perform electroforming until the cumulative current value reaches 000A, and then
An electroformed stamper with a thickness of 0 μm was obtained. After the electroforming was completed, we observed that there was no adhesion between the conductive ring and the electroformed film. Therefore, there was no separation between the conductive film and the master. When we measured the thickness of the electroformed film (micrometer, Mitutoyo), we found that it was φ300 mm inside the bent part of the conductive ring.
The film thickness was 300±5 μm, and the film thickness distribution was sufficiently good.

Example 2 A glass plate (manufactured by Asahi Glass Co., Ltd.) with a thickness of 10 mm and a size of 300 x 340 mm was used, and an uneven pattern of the same size with a pitch of 12 μm, a width of 3.0 μm, and a depth of 3000 A was formed on the surface. An ultraviolet curing resin (manufactured by Nippon Kayaku Co., Ltd., INC118) was sandwiched between the photomask and the photomask to a thickness of 50 μm and cured. After curing, the photomask was removed to obtain a glass master disk. A 270 x 310 mm hole was drilled in the center of a conductive ring with an outer diameter of 500 mm and the same thickness and material as in Example 1, and a 25 degree bend with a length of 10 mm was formed around the entire circumference of the hole. I made it. This master has an external diameter of φ500
It was installed in a mm master holder. After that, Example 1
Similarly, a conductive ring was placed in contact with the conductive ring at a distance of 5 mm from the outer circumference of the master. As in Example 1, it was firmly fixed using a lid with an outer diameter of 500 mm and a hole of 290 x 330 mm inside. Using the same electroforming solution, anode, and electroforming tank as in Example 1, the current value was 1A for 30 minutes, and then 30A.
(current density 290A/m2), electroforming was performed until the cumulative current value reached 9600A, and 20
An electroformed stamper of 0 μm was obtained. When observed in the same manner as in Example 1, there was no peeling between the master and the electroformed film. When the thickness of the electroformed film was measured in the same manner as in Example 1, it was found to have a good distribution of 200±4 μm in a range of 250×300 mm.

Example 3 A plate made of the same material and thickness as in Example 1 was made with an outer diameter of 400 mm.
The conductive ring was cut into a donut shape with an inner diameter of 315 mm, and the inner 15 mm of the conductive ring was bent at 45 degrees to form a bent portion. The same glass master disc as in Example 1 was used, the same master disc holder as in Example 1, the same anode, electroforming liquid, and electroforming tank as in Example 1. A master disc, a conductive ring, and a lid were installed in the same manner as in Example 1. Electroforming was performed using the same current conditions as in Example 1 to the same integrated current value as in Example 1. When the electroformed stamper produced in the same manner as in Example 1 was observed, there was no peeling between the master and the electroformed film. When the film thickness was measured,
The distribution was sufficiently good at 300±5 μm.

Comparative Example 1 Using the same glass master as in Example 1, the same master holder as in Example 1, and a conductive ring of the same material and thickness as in Example 1 with a center hole of φ345 mm, without bending. It was created in The same anode, electroforming solution, and electroforming tank as in Example 1 were used. Electroforming was performed using the same current conditions as in Example 1 to the same integrated current value as in Example 1. When we observed the electroformed stamper in the same manner as in Example 1, we found that the electroformed film adhered to the conductive ring during electroforming, and when the conductive ring was peeled off,
Peeling occurred between the electroformed film and the master disc. When the thickness of the electroformed film was measured, it was found to be 300±10 μm with good distribution.

[0016]

[Effects of the Invention] When the electroforming method of the present invention is used, electroforming is performed using a conductive ring having a bent portion at a predetermined angle and length, so that the electroformed film below the bent portion is The thickness can be reduced, thereby preventing the electroformed film from adhering to the conductive ring, and making it possible to obtain an electroformed stamper without peeling off the electroformed film from the master. In addition, since the conductive ring is conductive, the electroformed film adheres to the tip of the folded part, which prevents the electroformed film from swelling on the master outside the folded part of the conductive ring, resulting in a uniform thickness. An electroformed stamper can be obtained.

[Brief explanation of the drawing]

FIG. 1 is a schematic cross-sectional view of a conductive ring used in manufacturing the stamper of the present invention.

FIG. 2 is a schematic cross-sectional view of a conductive ring used in manufacturing a conventional stamper.

FIG. 3 is a schematic cross-sectional view of an electroforming device used for manufacturing a conventional stamper.

FIG. 4 is a general cross-sectional view of a general optical recording medium. (a) Optical disk, (b) Optical card

FIG. 5 is a schematic cross-sectional view showing a conventional stamper manufacturing method.

[Explanation of symbols]

1 Master disc holder 2　Original recording 3 Conductive ring 4 Bending part 5 Top lid 6 Electroformed film 7 Master holding part 11 Cathode 12 Anode 13 Electroforming tank 14 Motor 15 Electroforming tank lid 16 Baffle board 21 Transparent substrate 22 Track groove part 23 Optical recording layer 24 Spacer 25 Adhesive layer 26 Protective board 27 Center hole 31 Glass substrate 32 Resist layer 33 Track groove 34 Conductive film 35 Electroformed film

Claims (1)

[Claims] Claim 1. A method for manufacturing a stamper for molding an optical recording medium by electroforming a master disk on which a concavo-convex pattern corresponding to information to be recorded in advance on the optical recording medium is formed, comprising: a cathode; A conductive ring protruding into the electroforming liquid is installed at a predetermined length and at a predetermined angle between the master disc forming the master disc and the master disc holder that holds the master disc,
A method for electroforming a stamper for manufacturing an optical recording medium, characterized in that electroforming is carried out by applying current through the conductive ring from the outer periphery of the master.