JPH0525676A - Holder of master disk for producing stamper and delectroforming method with the same used therefor - Google Patents

Abstract

PURPOSE:To diminish the difference of thickness of an electroforming film in the face of a master disk by providing a dummy cathode to the outer circumferential part of the master disk used as a cathode and preventing a power line from being assembled in this outer circumferential part in the case of performing electroforming at a time for producing a stamper. CONSTITUTION:In the case of performing electroforming at a time for producing a stamper, the holder 103 of a master disk 101 for producing a stamper is used to hold the master disk 101 used as a cathode in the central part. Unevennesses are formed in the master disk 101 and a dummy cathode 102 having area of (1/1000-1/10) of the area of the master disk 101 is provided to the outer circumferential part. In the case of performing the above-mentioned electroforming, the potential difference between an anode 202 and the dummy cathode 102 is regulated to 1-1.5 times of potential difference between the anode 202 and the master disk 101. Further current density is regulated to 1-30A/m<2>.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electroforming method carried out for manufacturing an optical recording medium in which information is optically recorded / reproduced.

[0002]

2. Description of the Related Art Conventionally, magnetic materials such as magnetic tapes and magnetic disks and various semiconductor memories have been mainly used for recording various information. Such magnetic materials and semiconductor memories have the advantage that information can be easily written and read, but on the other hand, the contents of information can be easily tampered with, and high-density recording cannot be performed. I had one.

An optical information recording method using an optical recording medium has been proposed as a means for efficiently handling a wide variety of information for solving such problems, and an optical information recording carrier, a recording / reproducing method and A recording / reproducing device has been proposed.

The recording method on an optical recording medium as an information recording carrier is generally carried out by using a laser beam to volatilize a part of the optical recording layer on the information recording carrier or to change the reflectance. Alternatively, by deforming, information is recorded and reproduced by a difference in optical reflectance or transmittance.
In this case, the optical recording layer is a so-called DRAW (direct read after write) medium that can be "read directly after writing" without the need for development processing after writing the information, and high density recording. Since it is possible to write and additionally write, it is extremely effective as a recording / storing medium of information.

FIG. 4 is a diagram showing a general manufacturing process of a stamper for manufacturing an optical recording medium having the above characteristics.

As shown in FIG. 4 (a), a master having a concave / convex pattern 402 of a predetermined depth formed on a plate 401 made of glass or the like having a good flatness by using a resist or a photosensitive resin is prepared. . Next, as shown in FIG. 4B, a conductive film 403 is formed on the concave-convex pattern 402, the conductive film 403 is made conductive, and electroforming is performed as shown in FIG. 404 is formed.

Regarding the manufacturing method of such a stamper,
Various proposals have been made as described below. JP-A-5
In each of JP-A-9-177388, JP-A-60-017089 and JP-A-61-279699, a baffle plate is inserted between an anode and a cathode of an electroforming tank when performing electroforming. To improve the plate thickness distribution. Japanese Utility Model Application Laid-Open No. 58-141435 describes that foreign matter such as insoluble oxide slime and smut generated in an electroforming tank is removed in a preliminary tank in order to prevent the generation of pinholes. Further, Japanese Patent Application Laid-Open No. 62-209746 discloses that the traces of a current carrying jig at the time of electroforming are sealed with an ultraviolet curable resin to prevent penetration of an abrasive or the like during polishing.

[0008]

In the electroformed film formed by electroforming, the outer side of the master on which electric lines of force concentrate is thicker than the central part. For this reason, when polishing the back surface of an electroformed stamper, a two-step polishing process is performed, in which the thick portion of the electroformed film on the outer peripheral portion is roughly polished to the same thickness as the central portion and then the entire surface of the stamper is precisely polished. There is a problem that it is required and the processing steps are complicated.

Since the stress strength of the electroformed film is proportional to the film thickness, a strong stress is applied to the outer peripheral portion. Therefore, when peeling the electroformed film from the master, there is a problem that the electroformed film is peeled off so as to be rolled up.

The non-uniformity of the electroformed film thickness is caused by other than circular shape.
For example, it becomes particularly noticeable when a square master is used.

The present invention has been made in view of the above problems of the prior art, and an object of the present invention is to manufacture a stamper having a small difference in the thickness of the electroformed film in the master surface.

A holder for a stamper manufacturing master according to the present invention is a holder for a stamper manufacturing master which holds a master having an unevenness to be used as a cathode when performing electroforming during stamper manufacturing. Further, at least one or more pseudo cathodes are provided on the outer peripheral portion of the master held at the central portion.

Also, the electroforming method of the present invention is an electroforming method using the above-mentioned holder of the stamper manufacturing master, and a pseudo cathode is used together with the master as a cathode when performing electroforming.

[0013]

Since the pseudo cathode provided on the outer peripheral portion of the master together with the master can be used as the cathode during electroforming, it is possible to prevent electric lines of force from concentrating on the outer peripheral portion during electroforming. This makes it possible to reduce the difference in the thickness of the electroformed film on the master surface.

[0014]

Embodiments of the present invention will now be described with reference to the drawings.

1A and 1B are views showing the configuration of an embodiment of the present invention. FIG. 1A is a sectional view and FIG. 1B is a top view.

A disk-shaped master holder 103 supports the master 101 at its central portion, and a pseudo cathode 102 is provided on the upper surface of its outer peripheral portion.

FIG. 2 is a diagram showing a state in which electroforming processing is performed using the master holder 103 shown in FIG.

As shown in the drawing, the cathode 201 is a master disc 10.
1 and the pseudo-cathode 102 are arranged on the master disk holder 103, and are provided in the electroforming tank 203 so as to face the anode 202 with the baffle plate 206 interposed therebetween. The cathode 201 is a motor 204 provided outside the electroforming tank 203.
The electrocasting tank 203 is closed by the electrocasting tank lid 205. Further, a potential difference V1 is generated between the master 101 and the anode 202, and the pseudo cathode 102 and the anode 20
2, so that a potential difference V2 is generated between
08 are provided respectively.

In this embodiment, as described above, the master 1
01, not only the pseudo electrode 1 provided on the outer peripheral surface thereof
Since a voltage is also applied to 02, electroforming is performed in a state where the lines of electric force are averaged, and the electroformed film thickness formed is also averaged. As a result, for the polishing of the back surface of the stamper, it suffices to perform precision polishing once with the entire surface as a mirror surface, and the number of processing steps can be reduced compared to the conventional case.

The pseudo cathode 102 in the present invention is the master 1.
01 is a position where there is no electrical contact due to direct contact, and any position and shape can be freely selected as long as it can alleviate the concentration of electric lines of force around the outer periphery of the master 101. can do. The master 101 and the pseudo cathode 102 are preferably provided at positions separated by 1 mm or more.

FIG. 3 is a diagram showing the configuration of the second embodiment of the present invention.

The first embodiment shown in FIG. 1 is a pseudo cathode 10.
2 encountered a shape that continuously surrounds the entire outer periphery of the master 101, while the master holder 303 of this embodiment has a master 301
The outer peripheral portion of is surrounded by a plurality of pseudo cathodes 302 in a discontinuous manner. The plurality of pseudo cathodes 302 are the master 301
However, some of them may be arranged on the side surface of the master holder 303 if necessary.

In any of the embodiments shown in FIGS. 1 and 3, if the area of the pseudo cathode is too large, the efficiency of deposition on the master decreases, and if it is too small, electric lines of force concentrate on the outer periphery of the master. You can't prevent what you do. The size is preferably within the range of 1/1000 to 1/10 of the area of the master.

Next, regarding the two potential differences V1 and V2, if V1 is larger than V2, it becomes impossible to prevent electric lines of force from concentrating on the outer peripheral portion of the master 101.
If V2 is significantly larger than V1, deposition on the master 101 will not occur. A preferable relationship between the potentials V1 and V2 is that V2 is slightly larger than or equal to V1 and V2 is smaller than 1.5 times V1. Regarding the current density at the time of electroforming, it is sufficient to select a range in which no warp or stress occurs in the electroformed film, 1 to 30 A / dm ² can be selected, and a range of 3 to 10 A / dm ² is preferable. Can be used.

As the material of the pseudo cathode 102, any material can be used as long as it is an electroforming liquid used and does not cause dissolution, etching or corrosion. It is preferable to use a metal to be electroformed. Glass, ceramics or iron, which has been subjected to a conductive treatment with a metal with a low ionization tendency,
It is a metal or metal compound material such as chromium or nickel, and more preferably a metal material such as gold, copper or stainless steel. The surface of the pseudo cathode 102 may be flat or rough.

The present invention is described in more detail below by showing specific examples, but the present invention is not limited to these.

[Example 1] 300 × with a thickness of 10 mm
50 μ between a 340 mm glass plate and a photomask having the same size as the glass plate and an uneven pattern with a pitch of 12 μm, a width of 3.0 μm and a depth of 3000 Å on the surface.
The resin was cured by irradiating it with ultraviolet rays while sandwiching the ultraviolet curable resin having a thickness of m. After curing the resin, the photomask was removed to obtain a glass master. After making nickel 1000 Å by sputtering to make this conductive,
Outer diameter φ550mm with square opening of 0 × 330mm
It was installed on the circular master holder. As shown in FIG. 1, the master holder has an outer diameter of φ45 with a thickness of 0.5 mm.
A pseudo cathode (made of SUS304) having a 0 mm round shape and a square opening of 300 × 340 mm provided inside is installed on the same surface as the master of the upper lid of the master holder.

As the anode, a nickel ball was placed in a titanium basket and covered with a cotton cloth to prevent the outflow of dust.
As an electroforming liquid, 500 liters of a liquid mixed with the following composition was put into an electroforming bath of an electroforming bath of 150 liters and a preliminary bath of 350 liters, and the whole liquid was circulated at a cycle of 10 times / hour at a liquid temperature of 45 ° C. It was

Nickel sulfamate (tetrahydrate) 450 g / l Boric acid 30 g / l Pit inhibitor 5 ml / l The current density between the master and the anode was 0.1 A / dm ² for 30 minutes, then, The current density was increased to 5 A / dm ² and electroforming was performed until the integrated current value reached 10000 A · min, and an electroformed stamper with a thickness of 300 μm was obtained. In this electroforming process, the pseudo cathode and the master were always kept at the same potential.

After the electroforming was completed, the film thickness of the master was measured, and the film thickness in the central portion was in the range of 200 ± 5 μm.
The film thickness at the peripheral portion was in the range of 200 ± 10 μm and was sufficiently uniform.

[Example 2] The same master and the same master holder as in Example 1 were used. On the same surface of the master of the master holder as the master, at a position of 470 mm from the center of the master, circular pseudo cathodes having a thickness of 0.5 mm and a diameter of φ50 mm were arranged so that three pseudo cathodes were arranged on each side of the master evenly. The same electroforming apparatus and electroforming solution as in Example 1 were used, and the current density to the master was also the same as in Example 1. Further, regarding the potential difference between each of the master and the pseudo cathode and the anode, they were kept at the same potential as in Example 1. When the thickness of the electroformed film was measured in the same manner as in Example 1, both the central portion and the outer peripheral portion were in the range of 200 ± 10 μm, and the film thickness was sufficiently uniform.

[Example 3] The same master and the same master holder as in Example 1 were used. On the same surface as the master of the master lid of the master holder, at the position of 470 mm from the center of the master, pentagonal pseudo cathodes with a thickness of 0.500 and a diameter of 2 mm, three pentagonal cathodes are arranged evenly on each side of the master. Placed in. The same electroforming apparatus and electroforming solution as in Example 1 were used, and the current density to the master was also the same as in Example 1. The potential difference between the pseudo cathode and the anode was 1.2 times the potential difference between the master and the anode.

When the thickness of the electroformed film was measured in the same manner as in Example 1, both the central portion and the outer peripheral portion were 200 ± 10.
The thickness was in the range of μm and the film thickness was sufficiently uniform.

Comparative Example 1 The same master and the same master holder as in Example 1 were used. No pseudo cathode was provided. The same electroforming apparatus and electroforming solution as in Example 1 were used, and the current density to the master was also the same as in Example 1.

When the thickness of the electroformed film was measured in the same manner as in Example 1, the central portion was in the range of 200 ± 10 μm and the outer peripheral portion was in the range of 300 ± 10 μm, and the outer peripheral portion was thick. I got it.

[0036]

Since the present invention is constructed as described above, it has the following effects.

According to the first aspect of the present invention, by using the master and the pseudo cathode as the cathode during electroforming, it is possible to prevent the lines of electric force from being concentrated on the outer peripheral portion.

According to the second aspect, the above effect can be produced without lowering the deposition efficiency on the master.

In the method according to the third aspect, it is possible to prevent the electric lines of force from concentrating on the outer peripheral portion during electroforming, and to provide an electroformed stamper having a small difference in the thickness of the electroformed film in the master surface. There is an effect that can be produced.

In the method according to the fourth aspect, there is an effect that an electroformed stamper having a uniform film thickness in the master surface can be manufactured without lowering the deposition efficiency on the master disk.

In the method according to the fifth aspect, there is an effect that an electroformed stamper having a uniform film thickness within the surface of the master can be manufactured without causing warping or stress in the electroformed film. .

[Brief description of drawings]

FIG. 1 is a diagram showing a configuration of an embodiment of the present invention,
(A) is sectional drawing, (b) is a top view.

FIG. 2 is a diagram showing a state where an electroforming process is performed using the master holder 103 shown in FIG.

FIG. 3 is a diagram showing a configuration of a second exemplary embodiment of the present invention.

4A to 4C are diagrams showing a general manufacturing process of a stamper for manufacturing an optical recording medium.

[Explanation of symbols]

101,301 Master 102,302 pseudo cathode 103,303 Master holder 201 cathode 202 anode 203 Electroforming tank 204 motor 205 Electroforming tank lid 206 Baffle 207, 208 power supply

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Toshiya Yuasa             3-30-2 Shimomaruko, Ota-ku, Tokyo             Non non corporation (72) Inventor Kai Hill             3-30-2 Shimomaruko, Ota-ku, Tokyo             Non non corporation (72) Inventor Osamu Kaname             3-30-2 Shimomaruko, Ota-ku, Tokyo             Non non corporation (72) Inventor Naoki Kushida             3-30-2 Shimomaruko, Ota-ku, Tokyo             Non non corporation

Claims (5)

[Claims] 1. A holder for a stamper manufacturing master, which holds a master having concaves and convexes used as a cathode during electroforming during stamper manufacturing, the outer peripheral portion of the master being held at a central portion. Is provided with at least one or more pseudo cathodes. 2. The stamper manufacturing master holder according to claim 1, wherein the area of the pseudo cathode is 1/1000 to 1/10 of the master area.
Master holder for stamper manufacturing, characterized in that 3. An electroforming method using a holder for a stamper manufacturing master according to claim 1, wherein a pseudo cathode is used together with the master as a cathode when performing electroforming. 4. The electroforming method according to claim 3, wherein the potential difference between the anode and the pseudo cathode during electroforming is 1 to 1.5 times the potential difference between the anode and the master. An electroforming method characterized by: 5. The electroforming method according to claim 3, wherein the current density when performing electroforming is 1 to 30 A / dm ² .