JPH01285039A - Production of substrate for optical disk - Google Patents

Abstract

PURPOSE:To prevent the camber of a stamper and to enable the transfer of the patterns possessed by the stamper with high accuracy by providing a release agent layer which is formed of a low mol.wt. release agent and has <=80Angstrom thickness on the surface of the stamper having the prescribed patterns. CONSTITUTION:The release agent layer 13 which is formed of the low mol.wt. release agent and has <=80Angstrom thickness is provided on the surface of the stamper 1. Lubricants such as stearic amide and barium stearate are used as the release agent. A substrate 3 for optical disks is then brought into pressurized contact with the top of the developed radiation curing type resin 2 and is irradiated with radiations such as UV rays from above by a radiation source 4 by which the substrate is adhered to the resin. The substrate 3 adhered with the resin 2 on the surface and the stamper 1 are then stripped and the substrate for optical disks transferred with the patterns on the surface of the stamper 1 on the surface is obtd. The generation of the camber in the stamper 1 is thereby substantially obviated and the transfer of the patterns possessed by the stamper with the high accuracy is enabled.

Description

[Detailed Description of the Invention] <Industrial Application Field> The present invention relates to a method of manufacturing a substrate for an optical disk such as an optical recording disk or a magneto-optical recording disk that records and reproduces information using light such as a laser beam. Regarding.

<Prior Art> Optical discs are usually constructed by providing a recording film and a reflective film directly or indirectly on a transparent substrate having group bits for tracking control, addressing, etc. on the surface.

For example, magneto-optical recording disks usually include an amorphous magnetic thin film of rare earth elements and transition metals as a recording layer on a substrate.
Information is recorded by applying an external magnetic field while heating this recording layer to near the Curie point by irradiating the recording layer with light such as a laser beam.In addition, information is reproduced by irradiating the recording layer with light such as a laser beam. This is done by reading the change in the Kerr rotation angle.

The substrate used for such magneto-optical recording disks includes
Grooves or bits for tracking control and bits for addressing are formed.

In addition, optical discs such as compact discs (CDs)
A reflective film is provided on the bit side of the substrate on which bits carrying information are formed, and light such as a laser beam is irradiated from the opposite side of the substrate to the side on which the bits are formed. Read changes and reproduce information.

In addition to bits carrying information as described above, grooves or bits for tracking control and bits for addressing are also formed on substrates used in optical recording media.

In order to provide such grooves or bits on the surface of the substrate, for example, the so-called 2P method described below is used.

In the 2P method, first, a radiation-curable resin is spread on the surface of a stamper having a predetermined pattern on the surface, and a substrate is pressed onto the radiation-curable resin to transfer the pattern on the stamper surface to the resin. Next, the resin is cured by irradiation with radiation to bond the resin and the substrate, and then the resin layer and the stamper are peeled off to obtain an optical disk substrate to which the pattern on the surface of the stamper has been transferred.

In such a 2P method, if the mold releasability between the stamper and the resin layer is poor, the transfer to the resin surface may be poor or the stamper may easily warp.

Therefore, in order to improve the mold releasability, the surface of the stamper is coated with a film of a mold release agent. JP-A-62-293535 proposes the use of a polymer resin (polyethylene) as a mold release agent.

In this publication, a polyethylene resin solution is prepared, this solution is applied to the stamper surface using a spin cord, and heat treatment is performed to form a polyethylene film with a thickness of 0.01 μm (100 layers).

<Problems to be Solved by the Invention> However, since the pattern transferred to the surface of the substrate for an optical disk is minute, if a stamper having a release agent coating of the above thickness is used on the surface, it is difficult to transfer the pattern to the substrate surface. becomes defective, and the reproducibility of information decreases.

Furthermore, as described in JP-A No. 62-293535, when the mold release agent is formed from a high molecular weight substance such as polyethylene, a process such as heat treatment or irradiation with ultraviolet rays or electron beams is required. When using this method, the stamper tends to be deformed and it is difficult to obtain a highly accurate surface, and it is also difficult to obtain a uniform thin film.

SUMMARY OF THE INVENTION An object of the present invention is to provide a method for manufacturing an optical disc substrate in which warpage is less likely to occur in a stamper and a pattern of the stamper is transferred with high precision.

Means to solve problems〉 Such objects are achieved by the invention described below.

That is, the present invention spreads a radiation-curable resin on the surface of a stamper having a predetermined pattern, presses an optical disc substrate onto the spread radiation-curable resin, and then irradiates the radiation to remove the radiation. A method for manufacturing an optical disc substrate, in which a curable resin and the optical disc substrate are bonded, and then the optical disc substrate and the stamper are peeled off to obtain an optical disc substrate on which a pattern on the surface of the stamper is transferred to the surface. A method for manufacturing an optical disk substrate, characterized in that the stamper surface has a mold release agent layer made of a low molecular weight mold release agent and has a thickness of 80 Å or less.

Hereinafter, the specific configuration of the present invention will be explained in detail.

A cross-sectional view illustrating the invention in detail is shown in FIG.

In FIG. 1, a stand bar 1 is usually made of Ni or the like, and its shape can be various depending on the purpose, such as a disk shape. Further, its dimensions are also appropriately determined depending on the purpose. Further, on its surface, grooves and bits carrying information to be transferred to the optical disk substrate, or a matrix pattern of address bits are formed. The stand bar 1 is usually formed by electrolytic plating. Further, the pattern formed on the surface is a transfer of a pattern formed by photoetching or the like.

In the present invention, the surface of such a stand bar 1 is provided with a mold release agent layer 13 made of a low molecular weight mold release agent and having a thickness of 80 Å or less.

As the low molecular weight release agent, lubricants such as stearamide, barium stearate, zinc stearate, butyl stearate, and ethylene bisstearylamide are preferred.6 Among these, it is particularly preferable to use stearamide and zinc stearate. Preferably, if the thickness of the release agent layer exceeds 80 mm, poor pattern transfer is likely to occur.
In addition, more preferable results are obtained when the thickness of the mold release agent layer is 10 to 50.

Such a release agent layer can be formed using a vapor deposition method or a Langmuir method.
Preferably, the layer is laid by the projector method. There are no particular restrictions on the vapor deposition method or Langmuir-Prodgett method used, and the layer formation conditions may be appropriately selected depending on the type of mold release agent used.

When transferring the above-mentioned matrix pattern onto the surface of the optical disc substrate, first, the mold release agent layer 1 provided on the surface of the standber 1 is applied.
Radiation-curable resin 2 is spread on the surface of 3. As a method for spreading the radiation-curable resin, it is preferable to use a method of, for example, setting the stand bar 1 on a jig and discharging the radiation-curable resin onto it. The resin used in the method may be used, and there are no particular limitations.

Next, the optical disc substrate 3 is pressed onto the spread radiation curable resin 2 by a pressure means (not shown). A radiation source 4 irradiates radiation such as ultraviolet rays from above the pressed optical disc substrate 3 to harden the radiation curable resin 2, thereby bonding the radiation curable resin 2 and the optical disc substrate 3. Next, the optical disc substrate 3 on whose surface the radiation-curable resin 2 is adhered and the stand bar 1 are separated to obtain an optical disc substrate on which the pattern on the surface of the stand bar 1 has been transferred.

Note that the optical disc substrate 3 is made of a material that is transparent to the radiation irradiated from the radiation source 4 and to the information recording light and reproduction light. In the present invention, it is preferable to use glass or resin. As the resin, it is preferable to use acrylic resin, polycarbonate resin, epoxy resin, polyolefin resin, etc.

The thickness of the optical disc substrate 3 is usually about 0.5 to 3 mm, and the external shape is selected depending on the purpose.

The optical disc substrate thus obtained can be used as a magneto-optical recording medium by providing an amorphous magnetic thin film of rare earth element-transition metal as a recording layer. Also,
A reflective film such as Al1 can be provided on the surface of such a substrate, and the substrate can be used as an optical recording medium such as a compact disk.

<Example> Hereinafter, the present invention will be explained in further detail by giving specific examples of the present invention.

A Ni sukumba with a diameter of 150 mm and a thickness of 0.3 mm,
Manufactured by electrolytic plating. As a matrix pattern,
Groups with a pitch of 1.6 μm and a width of 0.8 μm were formed on the surface of the stand bar by a normal mask ring process. A mold release agent layer made of stearic acid amide was formed on the surface of this stamper to a thickness of 50 mm by vacuum deposition to obtain a stamper sample of the present invention (sample No. 1).

In addition, a stamper (Sample No. 2) having a release agent layer made of stearic acid amide and having a thickness of 100 mm was produced in the same manner as Sample No. 1. Furthermore, for comparison, a stamper (sample N
Sample No. 3) and a stamper without a release agent layer (Sample No. 4) were prepared.

Each of these stampers is placed in a jig, and after discharging radiation-curable resin (ultraviolet-curable acrylate) onto the stamper, a 130 mm diameter, 130 mm thick plate made of bisphenol A-based optical disc grade polycarbonate resin is placed on top of the radiation-curable resin. An optical disk substrate with a diameter of 1.2 mm was pressed. Next, ultraviolet rays were irradiated from the optical disc substrate side using a mercury lamp to bond the radiation curing resin and the optical disc substrate.

Next, the optical disk substrate was peeled off from each stamper, and optical disk substrates N were obtained from samples No. 1 to 4, respectively.
o, 11-14 were obtained. Optical disc substrate No. 11
The optical disk substrate No. 14 gave a signal at almost the same level, and the optical disk substrate No. 12 had a few defects but gave a signal at an acceptable level. On the other hand, optical disc substrate No. 13 had many defects and also had a low signal level.

Furthermore, when transfer was continued using samples No. 1 and 4, no signal disturbance occurred on the optical disc substrate transferred using samples No. In the case manufactured using No. 4, disturbances occurred in the outer peripheral tracking signal after 10 transfers.

In addition, a silicon nitride film and a Tbz+Fetz film were deposited on the surfaces of optical disc substrates Nos. 11 to 14 by sputtering.
A CC1y film was formed, and magneto-optical recording disk No.
, 21-24 were prepared.

When the tracking characteristics and recording/reproducing characteristics of these were measured, it was found that the magneto-optical recording disk No. 21.2
2 and 24 operated normally, but magneto-optical recording disk No. 23 was prone to errors and tracking loss.

From the above results, the effects of the present invention are clear.

<Operations and Effects of the Invention> Since the present invention uses a mold release agent layer with a thickness of 80 Å or less made of a low molecular weight mold release agent, according to the present invention, the mold releasability between the stamper and the optical disk substrate is good, and the stamper does not flex. It is possible to obtain an optical disc substrate in which the pattern of the stamper is transferred with high precision and which is less likely to occur.

[Brief explanation of the drawing]

FIG. 1 is a sectional view for explaining the present invention in detail. Explanation of the symbol ■...Stamper. 13... Mold release agent layer, 2... Radiation curable resin, 3... Optical disc substrate, 4... Radiation source

Claims (3)

[Claims] (1) Spread a radiation-curable resin on the surface of a stamper having a predetermined pattern, press an optical disc substrate onto the spread radiation-curable resin, and then irradiate the radiation-curable resin with radiation. and the optical disc substrate, and then peeling off the optical disc substrate and the stamper to obtain an optical disc substrate having a pattern on the surface of the stamper transferred to the surface. 1. A method for manufacturing an optical disc substrate, comprising: a mold release agent layer formed from a low molecular weight mold release agent and having a thickness of 80 Å or less on the surface of a stamper. (2) The method for manufacturing an optical disk substrate according to claim 1, wherein the release agent layer is formed by a vapor deposition method. (3) The method for manufacturing an optical disk substrate according to claim 1, wherein the mold release agent layer is formed by a Langmuir-Prodgett method.