JPH05114175A - Method for electrocasting stamper for production of information recording medium - Google Patents

Abstract

PURPOSE:To obtain the stamper which is free from 'cavities', projections, recesses, etc., by executing electrocasting while applying a pressure fluctuation to an electrocasting liquid at an arbitrary point of the time from the start of the electrocasting before the end of the electrocasting. CONSTITUTION:A cathode 1a and an anode 2 consisting of glass disks formed with conducting films on the surfaces are disposed in an electrocasting chamber 3. The cathode 1a is rotated by a motor 4 and a vacuum pump 6 is connected to the electrocasting chamber 3 so that the pressure in the chamber 3 can be reduced. The bubbles generated on the surfaces of the cathode 1a by the electrocasting are rapidly expanded when the inside of the chamber 3 is evacuated by the pump 6 after the start of the electrocasting. The buoyancy is thereby increased and the bubbles are parted from the electrodes. A valve 8 is opened to restore the atm. pressure in the chamber 3 after the bubbles are removed from the electrodes. The bubbles sticking or generated to or on the surface of the cathode 1a can be removed by repeating such operation. The stamper free from the 'cavities', projections, recesses, etc., is thus obtd.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an information recording medium for recording and reproducing information such as an optical card, an optical disc, a magneto-optical disc or a substrate of the medium (hereinafter referred to as an information recording medium etc.).
The present invention relates to an electroforming method of a stamper for molding an information recording medium, etc.

[0002]

2. Description of the Related Art Conventionally, a stamper for molding an information recording medium or the like is usually disclosed in JP-A-61-284843 and JP-A-5-58.
It is manufactured by a method as described in Japanese Patent Laid-Open No. 8-141435, "Point No. 5 of optical disk process technology" (Japan Industrial Technology Center) and the like.

That is, specifically speaking, FIG. 3 (a)
As shown in (e) to (e), first, a photoresist 21 is applied to the surface of the glass substrate 22 (see FIG. 3A), and a fine pattern 21a of irregularities such as tracking grooves and information pits is formed thereon. By doing the glass master 1
To get (See Fig. 3 (b))

Next, a conductive film 23 is formed on the surface of the glass master 1 (see FIG. 3C) to obtain a glass master 1a on which the conductive film is formed, and then the conductive film 23 is formed. A metal film 24 is formed on the glass by electroforming (see FIG. 3 (d)), and the conductive film 23 and the metal film 24 are integrally separated from the glass master 1 at the same time, and a stamper (mother for molding an information recording medium, etc.) is formed. , Master) 25 is manufactured. (Fig. 3
(See (e))

General electroforming method (Electroform)
ing) process is as described above. In particular,
3 (c) to 3 (d) of the electroforming process will be described in detail, the conductive film 23 in FIG. 3 is formed by a method such as vapor deposition of metal in vacuum or sputtering, and the material is gold or nickel. And nickel is often used.
It is common to deposit a nickel layer having a thickness of 50 to 100 nm on the fine pattern 21a having irregularities such as tracking grooves and information pits by a sputtering method.

Next, as shown in FIG. 3 (d) of the electroforming step, in the preceding step, organic impurities of nickel sulfamate electroforming solution are segregated by periodical activated carbon treatment, and metal ions are segregated by electrolytic cleaning. , We are trying to remove it.
The liquid composition of the nickel sulfamate electroforming liquid used here has the following composition.

[0007] nickel sulfamate tetrahydrate _{[Ni (NH 2 SO 3)} 2 · 4H 2 O] 500g / l boric acid _{[H 3 BO 3] 35~38g /} l pit inhibitor 2.5 ml / l nickel sulfamate The pH of the electroforming liquid is usually adjusted to 3-5. Fluctuations in pH cause internal strain and curling of the stamper, so adjustment is made by direct addition of nickel bromide, sulfamic acid, caustic soda, or the like.

Next, as shown in FIG.
Is used as an anode, and the glass master 1a having the conductive film formed thereon is used as a cathode, while the motor 4 rotates the glass master 1a having the conductive film formed thereon, electricity is applied in the nickel sulfamate electroforming solution 5. By doing so, only nickel metal can be deposited on the glass master 1a on which the conductive film is formed. The heater 10 is used to control the liquid temperature,
The set temperature is 50 to 55 ° C.

When performing electroforming, a baffle plate should be inserted between the anode and the cathode of the electroforming tank to improve the plate thickness distribution (JP-A-59-177388 and JP-A-60-1).
7089, JP-A-61-2799699),
In order to prevent pinholes, foreign matters such as insoluble oxide slime and smut generated in the electroforming tank are removed in a preliminary tank (Japanese Utility Model Laid-Open No. 58-141435), and the electrode surface during electroforming. Ultrasonic waves are applied to the electroforming liquid in order to remove the gas generated or adhering to it (Japanese Patent Application No. 3-5610).
No.) things are being done.

[0010]

Conventionally, as shown in FIG. 4, a glass master 1a having a conductive film for a cathode is directed downward and fixed so as to face the anode 2, and electroforming is performed. There is. This is because if insoluble dust (slime or smut) of the anode generated from the anode 2 is generated during electroforming, and the cathode 1a is facing upward or sideways, these dust will not be discharged to the cathode. This is to prevent them from adhering to the surface or coprecipitating these foreign substances on the surface of the cathode.

When electroforming is performed with the glass master disk 1a on which the conductive film of the cathode is formed facing downward, when gas or the like is trapped, or when gas is generated, these gases are deposited on the surface of the cathode 1a. There is a problem in that the formation rate of the electroformed film becomes non-uniform due to being confined, and “spots” (voids), protrusions, and depressions are generated.

The present invention has been made for the purpose of solving the above problems, and a stamper for manufacturing an information recording medium, which records and reproduces information by changing the optical characteristics by irradiation of a light beam, is used as a master disc. It is intended to provide an electroforming method capable of obtaining a stamper free from "su" (voids), protrusions and dents in a method of manufacturing by performing electroforming.

[0013]

That is, according to the present invention, the optical characteristics are changed by irradiation of a light beam to record / record information.
In a method of manufacturing a stamper for manufacturing an information recording medium to be reproduced by electroforming on a master having an uneven pattern corresponding to information to be recorded, at any time from the start to the end of electroforming Then, the electroforming method of the stamper for manufacturing an information recording medium is characterized in that the electroforming is performed while the pressure of the electroforming liquid is changed.

The present invention will be described in detail below. According to the present invention, an information recording medium manufacturing stamper that records and reproduces information by changing the optical characteristics by irradiation of a light beam is electroformed on a master having a concavo-convex pattern corresponding to the information to be recorded. In the method of manufacturing a stamper by, in the gap where the anode and the cathode face each other, at any time from the start to the end of electroforming,
An object of the present invention is to provide a method of electroforming a stamper that does not have "su" (voids), protrusions, or dents by performing electroforming while applying pressure fluctuations to the electroforming liquid.

That is, by using the electroforming method of the present invention, it is possible to effectively remove the gas generated or attached on the cathode.
There is an advantage that an electroformed stamper without a dent can be obtained.

FIG. 1 is a sectional view showing an example of an electroforming apparatus used in the electroforming method of a stamper for producing an information recording medium of the present invention,
FIG. 2 is a sectional view showing another example of the electroforming apparatus used in the electroforming method of the stamper for manufacturing an information recording medium of the present invention. Figure 3
(A)-(e) is process explanatory drawing which shows the manufacturing method of the stamper for information recording media by a general electroforming method.

In the electroforming apparatus of FIG. 1, 5 is a nickel sulfamate electroforming liquid for depositing nickel metal for electroforming, 3 is an electroforming tank for containing the nickel sulfamate electroforming liquid, 1 l Is a filtration filter that removes dust and impurities by circulating the nickel sulfamate electroforming solution in the electroforming tank, 9 is a nickel chip for forming a metal film on a glass master that has been subjected to electroconductivity, and 10 is a solution temperature. It is a heating heater for adjusting.

Further, in FIG. 1, reference numeral 12 indicates that when the liquid composition of the electroforming liquid is controlled, a required amount of the electroforming liquid composition is added in advance and the mixture is rapidly mixed with the electroforming liquid in the electroforming tank. An electroforming liquid adjusting tank for enabling 14 is a pressurizing pump P for feeding the electroforming liquid or the electroforming liquid adjusting liquid from the adjusting tank to the electroforming tank.
Reference numerals 1 and 13 denote pressurizing pumps P2 for feeding the electroforming liquid from the electroforming tank into the liquid adjusting tank.

Reference numeral 1 denotes a glass master disk having a conductive film formed on a glass master disk having an uneven fine pattern such as tracking grooves and information pits, and 15 a holder for holding the glass master disk 1a having the conductive film formed thereon. 4 is a motor for rotating the holder and the glass master, 16 is a holder 1
A shaft that connects the motor 5 and the motor 4 and transmits the rotational force,
Reference numeral 17 is a hatch, and reference numeral 18 is a seal material that substantially shuts off the electroforming tank from the outside while the holder unit is mounted in the electroforming tank.

On the other hand, in the process chart of the general electroforming method showing the method of manufacturing the stamper for molding the information recording medium of FIG. 3, 22 is a glass substrate such as soda lime glass, and 21 is for patterning on the glass substrate. Photoresist, 21
Reference numeral a is a fine pattern of irregularities such as tracking grooves and information pits obtained by exposing and developing the photoresist, and 1 is a fine pattern of irregularities such as tracking grooves and information pits formed on a glass substrate. The glass master 23 obtained by the above-mentioned process, 23 is a conductive film provided by a pretreatment for forming a metal film on the glass master, and 1a is provided with a concavo-convex pattern such as a tracking groove or an information pit pattern. A glass master having a conductive film formed on the glass master, 24 is a metal film formed on the glass master having the conductive film formed by electroforming, and 25 is a glass master that is a combination of the conductive film and the metal film. It is a stamper for molding an information recording medium or the like obtained by further peeling.

In a method of manufacturing a stamper for molding an information recording medium or the like, as shown in FIGS. 3A to 3E, first, a photoresist 21 is applied to the surface of a glass substrate 22 (see FIG.
(Refer to (a)), and the glass master 1 is obtained by further forming a fine pattern 21a of irregularities such as tracking grooves and information pits. (See Fig. 3 (b))

Next, a conductive film 23 is formed on the surface of the glass master 1 (see FIG. 3C) to obtain a glass master 1a having the conductive film formed thereon, and then the conductive film 23 is formed. A metal film 24 is formed by electroforming on the substrate (see FIG. 3D), and the conductive film 23 and the metal film 24 are integrally separated from the glass master 1 at the same time to form a stamper 25 for molding an information recording medium or the like. obtain. (See Fig. 3 (e))

FIG. 1 is a sectional view showing the electroforming step of FIG. 3D, in which the anode 2 and the cathode 1 are placed in the electrocasting tank 3 at positions facing each other. The cathode 1 is rotated around a shaft by a motor 4 while facing downward. A vacuum pump 6 is connected to the electroforming tank 3 so as to reduce the pressure inside the electroforming tank. The bubbles generated on the surface of the cathode 1a by electroforming expand rapidly when the electroforming tank is evacuated by the vacuum pump 6,
Buoyancy increases and bubbles move away from the electrode. A trap 7 is provided between the vacuum pump 6 and the electroforming tank 3 so that vapor of the electroforming liquid does not enter the vacuum pump. After the bubbles are removed from the electrode, the valve 8 is opened and the pressure in the electroforming tank is returned to normal pressure. By repeating this operation during electroforming, it is possible to repeatedly remove the bubbles that have adhered to or generated on the surface of the cathode. If the electroforming liquid is continuously placed under vacuum for a long time, a large amount of the electroforming liquid will evaporate, which is not preferable. The time for which the electroforming liquid is placed under vacuum is, for example, within 10 minutes at 50 ° C. and 100 mmHg, preferably within 5 minutes. The degree of vacuum is preferably equal to or lower than the saturated vapor pressure of the electroforming liquid at that temperature.

Next, FIG. 2 shows another embodiment of the electroforming method for a stamper according to the present invention. In this case, the electroforming tank 3 is applied with pressure so that the inside of the electroforming tank can be pressurized. The pressure pump 6a is connected. The bubbles generated on the cathode surface by electroforming are reduced by pressurizing the inside of the electroforming tank by the pressure pump 6a. Next, when the valve 8 is opened and returned to normal pressure, the bubble expands rapidly, the buoyancy increases, and the bubble separates from the electrode. The higher the pressure applied, the more effective it is, but if it is too high, the electroforming tank must be strengthened. It is preferably about 10 atm. After the bubble is removed from the electrode, the valve 8 is closed and the pressure is applied again. By repeating this operation while electroforming is performed, it is possible to repeatedly remove the air bubbles adhered to or generated on the surface of the cathode.

[0025]

The stamper electroforming method of the present invention removes the gas generated or adhering to the cathode master surface by changing the pressure of the electroforming liquid at any time from the start to the end of electroforming. By doing so, it is possible to obtain an electroformed stamper having no "su" (void), protrusions, or dents.

[0026]

EXAMPLES The present invention will be described in detail below based on examples, but the present invention is not limited to the examples described below.

Example 1 A photoresist (AZ1300, manufactured by Hoechst Japan) was spin-coated on a glass plate (Asahi glass) having a thickness of 10 mm and a diameter of 355 mm to a thickness of 0.11 μm, and then a laser exposure machine (manufactured by Matsushita Electric Co., Ltd.) was used. ) To expose and develop the pattern,
A concavo-convex pattern having a pitch of 1.6 μm, a width of 0.7 μm and a depth of 1100 Å was formed. Then 1 nickel
The film was sputtered to a thickness of 000Å for conductivity treatment. The outer diameter of the glass plate having this uneven pattern is 400 m
It was fixed to a round master holder having a taper of m, an angle of 45 degrees, and a length of 10 mm, and electroforming was performed using the apparatus shown in FIG. The anode used was one in which a nickel ball was placed in a titanium basket and covered with a cotton cloth to prevent dust from flowing away.

As an electroforming liquid, 500 liters of a liquid mixed with the following composition was placed in an electroforming bath having an electroforming tank of 150 liters and a preliminary tank of 350 liters, and a liquid temperature of 45 ° C. and pH.
In the state of 4.0, the whole liquid was circulated in a cycle of 10 times / hour.

Nickel sulfamate (tetrahydrate) 450 g / l Boric acid 30 g / l Pit preventive agent 5 ml / l The current condition is to initially flow at 3 A for 30 minutes, then increase the current to 50 A, and integrate 13000 A minutes. Electroforming was performed until the current value was reached. For evacuation, a vacuum pump was used to reduce the pressure to 70 mmHg over 5 minutes, and then the valve was opened to rapidly return to normal pressure. After 10 minutes, the pressure was reduced again, and the pressure was reduced to 70 mmHg over 5 minutes in the same manner, and the valve was similarly opened. This operation was repeated from the beginning to the end of electroforming. In this way, an electroformed stamper having a thickness of 300 μm was obtained.

The surface of the stamper thus obtained was visually observed, and no "su" (void), protrusions or dents were found.
Even if you try to polish this stamper to half the thickness,
No "su" (voids), protrusions, or dents were found.

Example 2 Using the apparatus shown in FIG. 2, electroforming was performed in the same manner as in Example 1 except that the pressurizing operation was performed. The pressurizing operation was carried out by pressurizing to 7 atm over 5 minutes, then opening the valve and rapidly returning the pressure to normal pressure. After 10 minutes, the pressurization was started again, the pressure was similarly increased to 7 atm over 5 minutes, and the valve was similarly opened. This operation was repeated from the beginning of electroforming to the end thereof, as in Example 1. In this way, electroforming was performed up to the same integrated current value as in Example 1.

When the electroformed stamper thus obtained was observed, no "su" (void), protrusions, or dents were observed on the stamper surface. Even when polishing was performed to a half thickness as in Example 1, no "voids" (voids), protrusions, or depressions were observed.

Comparative Example 1 Using the same glass master as in Example 1, the same master holder as in Example 1, the same anode as in Example 1, an electroforming liquid, and an electroforming tank were used. This time, the electroforming tank was not pressurized or depressurized, and the pressure inside the electroforming tank was constant from the beginning of electroforming to the end of electroforming. The current conditions were the same as in Example 1, and electroforming was performed up to the same integrated current value as in Example 1.

Observation of the electroformed stamper surface in the same current condition as in Example 1 and in the same manner as in Example 1 revealed that
No (voids), protrusions, or dents were observed. When polishing was performed to half the thickness in the same manner as in Example 1, a large number of dents having a diameter of 0.1 to 0.2 mm were observed over the entire surface of the stamper.

[0035]

As described above, when the electroforming method of the present invention is used, the pressure can be changed even if bubbles are present in the cathode master plate or the taper part of the master holder housed in the electroforming tank. Since the bubbles can be removed by this, the generation of the electroformed film is not disturbed, and the formation speed of the electroformed film becomes uniform. Therefore, it is possible to obtain the effect that "su" (void), protrusions, and depressions are not generated in the electroformed film. In particular, when electroforming is performed using a square master, the gas is likely to stay at the corners, so the effect of removing the gas by varying the pressure is large.

[Brief description of drawings]

FIG. 1 is a sectional view showing an example of an electroforming apparatus used in an electroforming method of a stamper for manufacturing an information recording medium of the present invention.

FIG. 2 is a cross-sectional view showing another example of the electroforming apparatus used in the electroforming method of the stamper for manufacturing an information recording medium of the present invention.

FIG. 3 is a process explanatory view showing a method for manufacturing a stamper for an information recording medium by a general electroforming method.

FIG. 4 is a sectional view showing an example of an electroforming apparatus used in a conventional electroforming method of a stamper for manufacturing an information recording medium.

[Explanation of symbols]

 1 glass master 1a conductive film forming glass master (cathode) 2 anode 3 electroforming tank 4 motor 5 electroforming liquid 6 vacuum pump 7 trap 8 valve 9 nickel tip 10 heating heater 11 filter 12 adjusting tank 13 pressurizing pump P2 14 addition Pressure pump P1 15 Master holder 16 Shaft 17 Hatch 18 Flexible hatch 21 Photoresist 21a Fine pattern 22 Glass substrate 23 Conductive film 24 Metal film 25 Stamper for molding information recording medium etc.

 ─────────────────────────────────────────────────── ─── Continued Front Page (72) Inventor Toshiya Yuasa 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc. (72) Inventor Hisanori Hayashi 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Co., Ltd. (72) Inventor Hirofumi Uetakahara 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc. (72) Inventor Naoki Kushida 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc.

Claims (1)

[Claims] 1. A stamper for manufacturing an information recording medium, which records / reproduces information by changing optical characteristics by irradiation of a light beam, is electroformed on a master having a concavo-convex pattern corresponding to information to be recorded. In the method of producing by performing the electroforming, the electroforming of the stamper for producing an information recording medium is characterized in that the electroforming is performed while varying the pressure of the electroforming liquid at any time from the start to the end of electroforming. Casting method.