KR100364136B1 - Stamper-supporting mold coated with diamond-like carbon film for molding data-recording disks and its manufacturing method - Google Patents

Abstract

The present invention relates to a stamper paper mold for forming an information recording disk coated with a diamond-like carbon film, and a manufacturing method thereof, comprising: a stamper for transferring a certain shape to a disk, and a stamper that is in close contact with the stamper and supports the stamper at the bottom of the stamper. An information recording disk molding comprising a stamper mould, a press mold movable up and down with a predetermined space on the stamper, and a ring formed around the stamper and in close contact with the stamper and stamper mould. In the apparatus, the stamper-type die has an amorphous silicon layer formed on a surface in contact with the stamper, and forms a first diamond-like carbon film on the amorphous silicon layer and a lower hardness on the first diamond-like carbon film. 2 diamond-like carbon film is formed It provides a diamond-like carbon film-coated information storage disc for supporting a mold forming a stamper and a method for manufacturing the same that.

Description

STAMPER-SUPPORTING MOLD COATED WITH DIAMOND-LIKE CARBON FILM FOR MOLDING DATA-RECORDING DISKS AND ITS MANUFACTURING METHOD}

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a stamper mold for forming an information recording disk coated with a diamond-like carbon film and a manufacturing method thereof.

Stampers used in molding machines for information recording discs such as CDs, CD-ROMs, DVDs, MDs, magneto-optical discs are susceptible to damage as the molding process is repeated.

1 shows an example of a mold apparatus for forming a disk. The disc for manufacturing the information recording disk is composed of a stamper (1), a stamper gripping mold (2) for supporting the stamper, and a press mold core (3) moving back and forth from the opposite side of the stamper gripping mold. The presence of the ring 4 forms a closed molding space for these four parts. In the molding step, the plastic 5 is charged into the closed space and press-molded, whereby the step of transferring the shape of the stamper at the same time as the molding is performed. In this process, the stamper is a key part that has the information to be recorded. In order to improve the productivity of this process, the stamper supporting type (2) supporting the stamper is used to protect the stamper (1) from being damaged. Action should be taken. If damage occurs to the stamper, the expensive stamper must be replaced, resulting in increased costs and reduced productivity, thus increasing production costs.

The stamper moss mold 2 is made of a material in which the surface hardness is improved by heat-treating carbon steel, and the surface in contact with the stamper is precisely ground to prevent damage to the stamper during the molding process. This precision polishing is a measure to suppress the damage of the stamper caused by friction between the surface of the stamper mold and the back of the stamper as the expansion and contraction of the stamper occurs due to heat during the forming process, but the coefficient of friction between the stamper mold and the spamper Because of its large size, precise polishing alone does not sufficiently suppress the damage to the stamper. Moreover, since high pressure is applied between the stamper and the stamper mold, not only damage to the surface of the stamper may occur, but also severe cracking of the stamper may occur, and thus traces of cracks may be transferred to the surface of the disk to be formed. Therefore, in order to improve the wear resistance of the stamper, TiN or the like was coated on the surface of the stamper girder in contact with the stamper to obtain some improvement effect, but it was not possible to suppress the damage of the stamper surface or to obtain lubricity between the stamper girders and the stamper. Not enough

Japanese Patent Laid-Open No. Hei 10-202668 discloses a disk forming method which improves the damage of the stamper surface by coating a diamond-like carbon film on the back of the spamper. However, in order to coat the back side of the stamper, the stamper needs to be cleaned and loaded into a vacuum chamber, and there is a high risk of damaging the information recording layer of the expensive stamper during handling and coating of the stamper. In addition, in order to suppress the damage of the stamper due to the temperature rise during the coating of the stamper, a complicated coating apparatus such as a cooling apparatus must be provided.

It is therefore an object of the present invention to suppress damage to the surface of the stamper of the information recording disk forming apparatus and to provide excellent lubricity between the stamper mold and the stamper, thereby prolonging the life of the stamper and thus preventing the quality of the disk to be manufactured.

1 is a configuration diagram of an information recording disk molding die apparatus.

Figure 2 is a schematic diagram of the synthesis equipment used in the present invention.

3 is a photograph of a mold coated by the present invention.

*** Explanation of symbols for main parts of drawing ***

1: stamper 2: stamper now type

3: Press mold core 4: Ring

11: Chamber 13: Gas supply part

16: Power supply 17: Vacuum meter

In order to achieve the above object, the present invention provides a stamper which transfers a certain shape to a disk, a stamper which is in close contact with the stamper and supports the stamper at the bottom of the stamper, and has a predetermined space above the stamper. And a press mold movable downward, and a ring formed around the stamper and in close contact with the stamper and the stamper mould, wherein the stamper mould is formed on a surface in contact with the stamper. A second diamond-like carbon film having an amorphous silicon (Si) layer formed thereon, and forming a first diamond-like carbon film on the amorphous silicon layer, and having a lower hardness than the first diamond-like carbon film on the first diamond-like carbon film. Diamond-shaped carbon film characterized in that the nose The information provides recording disk molding mold for a stamper support.

The first diamond-like carbon film has a hardness of 10 to 40 GPa, the film has a thickness of 1 to 10 µm, the second diamond-like carbon film has a hardness of less than 10 GPa, and the film has a thickness of 0.01 to 2 µm. The thickness of the amorphous silicon layer is 5 to 100 nm.

In addition, the present invention is to place the mold on the cathode in the chamber and then pump the chamber to a vacuum, supply the discharge gas to the chamber and discharge the high-frequency discharge gas to the chamber dry cleaning the surface of the mold, supplying SiH ₄ to the chamber And discharging at high frequency to coat an amorphous silicon (Si) layer on the surface of the mold, supplying a hydrocarbon compound to the chamber, and discharging at high frequency to coat a first diamond-like carbon film on the amorphous Si layer formed on the mold. Provided on the diamond-like carbon film is a stamper-shaped manufacturing method for forming a diamond-shaped carbon film coated information recording disk comprising the step of coating a second diamond-like carbon film having a lower hardness.

Enhances the stamper's durability by forming a bonding layer to improve adhesion with diamond-like carbon film on the stamper-type surface where friction occurs in contact with the stamper, and coating a diamond-like carbon film having excellent lubricity and wear resistance on the bonding layer. You can.

Diamond-like carbon (DLC) film is one of the solid carbon films having physicochemical properties similar to diamond, and has the advantages of low synthesis temperature, smooth surface and easy control of physical properties. In particular, the surface energy is very low, it has the advantage of excellent releasability with heterogeneous materials and excellent chemical stability. In addition, the material has excellent wear resistance and lubrication properties, and is highly applicable to wear resistant solid lubricants. Therefore, the material is used in many fields such as computer hard disks, video heads and head drums, as well as tools for machining such as drills.

Diamond-like carbon film has a very wide range of physical properties depending on the synthetic conditions. For example, the hardness of the film may vary from 7 to 70 GPa depending on the energy of the carbon-containing particles reaching the substrate. In the case of diamond-like carbon film, the wear resistance also increases with increasing hardness, but the coefficient of friction between the substrate steel and the film is maintained at 0.1 to 0.2. Therefore, in the present invention, in order to protect the stamper, after coating the diamond-like carbon film having a high hardness as a first layer on the stamper support type with a thickness of 1 to 10 µm, the diamond-like carbon film having a low hardness as the second layer is 0.01 to Coating at a thickness of 2 μm gives the stamper high wear resistance and lubricity. If the thickness of the first layer and the second layer is too large, the residual stress increases, so that stable coating is difficult. As for the hardness of a diamond-like carbon film, 10-40 GPa is suitable for a 1st layer, since it is difficult to form a stable film because a residual stress becomes high when hardness becomes too large similarly to the thickness of a film. Since the second layer is for imparting lubricity rather than wear resistance, a hardness of less than 10 GPa is suitable.

For the synthesis of diamond-like carbon film, carbon ions must be formed and these ions collide with the surface to be synthesized with high energy. Various methods such as plasma CVD method, sputtering method, ion beam synthesis method, laser ablation, etc. Combined synthesis techniques are used.

In the embodiment of the present invention, the plasma CVD method was mainly used as a method of synthesizing the diamond-like carbon film. However, the scope of the present invention is not limited to this method. Any method for synthesizing the diamond-like carbon film having a smooth surface and excellent lubricity and wear resistance can be used for the purpose of the present invention.

Hereinafter, the present invention will be described in more detail with reference to the accompanying drawings.

2 is a schematic diagram of the synthesis apparatus used in the present invention. The synthesizing apparatus is largely divided into four parts, such as the synthesis chamber 11, the vacuum system 17, the gas supply unit 13, and the high frequency (RF) power supply system 16 of 13.56 MHz. The mold 15 to which the film is synthesized is positioned at the cathode 14 in the chamber 11. In order to prevent the distortion of the plasma caused by the height of the mold 15, the cathode 15 has the same surface height as that of the cathode. Design it. Reference numeral 12 denotes a plasma generated by high frequency.

An example of the coating of the diamond-like carbon film is as follows. Using a vacuum system in the mold for 60 minutes at pressure conditions of 4 mTorr, 8 W / cm ² after pumping pressure to 10 ⁵ Torr or less, while supplying argon (Ar) as discharge gas using a high frequency discharge in argon in the chamber The surface was dry washed. In order to further improve the adhesion of the film after dry cleaning, the synthetic gas was changed to SiH ₄ , and an amorphous Si layer of about 50 nm was synthesized as an adhesion promoting layer at a synthesis pressure of 20 mTorr and 0.3 W / cm ² for 2 minutes.

Various hydrocarbon compounds may be used for the synthesis of the diamond-like carbon film by plasma CVD. In the present invention, benzene is used which has a high synthesis rate and easy film property control. In addition to benzene, methane, ethane, acetylene and the like can also be used. The synthesis pressure was fixed at 10 mTorr, the synthesis temperature was changed from 20 ℃ to 50 ℃, and the high frequency power density was changed from 0.05 to 1.5 W / cm ² synthesized the first and second diamond-like carbon film. As the high frequency power density applied for synthesis increased, the hydrogen content in the film decreased, but the density, hardness, and residual stress of the film monotonously increased, but the characteristics of the film were independent of temperature changes. In this embodiment, as the power density increases, the film properties change from polymer to diamond.

As a result of using a die coated with a diamond-like carbon film in a disk forming process for information recording, when only the first diamond-like carbon film of high hardness was coated on the stamper, damage was observed on the back side of the stamper as the forming process proceeded. When the low hardness second diamond-like carbon film was also coated, no damage to the stamper was observed even in 300,000 operations.

Figure 3 is a photograph showing a stamper current mold coated by the above plasma CVD method.

The thickness of the coated film was adjusted from 1 to 4 μm according to the example. The adhesion of the coating layer tested by the scratch test was 30N. The friction coefficient of the coating layer on the bearing ball had a value between 0.1 and 0.2 regardless of the high frequency power density.

As a result of applying the diamond-coated carbon film-coated die to the disk forming process, it was confirmed that the stamper had an effect of significantly improving the life of the stamper under optimum coating conditions.

A die coated with TiN and a die coated with a diamond-like carbon film according to the present invention were used in an information recording disk forming process to obtain the following results. The life span of the stamper was 250,000 to 300,000 times when the diamond-like carbon film was coated, which was 6 to 10 times longer than the 30,000 to 50,000 times when TiN was coated. In addition, as a result of examining the quality of the molded disk, when TiN was coated, there was a tendency to decrease forging according to the number of stamping, but when the diamond-like carbon film was coated, no degradation of the disk quality was observed during the life of the stamper. It wasn't.

According to the present invention, a die coated with a diamond-like carbon film having high lubrication and wear resistance is used for an information recording disk forming apparatus, which not only significantly improves the life of the stamper under the optimum coating conditions but also manufactures the end of the life of the stamper. The quality of the burned disc does not decrease. In addition, due to the excellent corrosion resistance of the diamond-like carbon film it is possible to improve the corrosion resistance of the stamper mold. Therefore, the productivity of the disk forming process can be increased. In addition, the diamond-coated carbon film coated mold can be re-coated after removing the diamond-like carbon film can be reduced cost effect.

Claims (10)

A stamper for transferring a predetermined shape to the disk, a stamper mold in close contact with the stamper and supporting the stamper at the bottom of the stamper, a press mold movable up and down with a predetermined space above the stamper; An information recording disk forming apparatus comprising a ring formed around the stamper and in close contact with a stamper and a stamper mould, wherein the stamper mould is provided with an amorphous silicon (Si) layer on a surface in contact with the stamper. And a first diamond-like carbon film is formed on the amorphous silicon layer, and a second diamond-like carbon film having a lower hardness is formed on the first diamond-like carbon film. Stamper for molding information recording discs now. The stamper paper mold for forming an information recording disk coated with a diamond-like carbon film according to claim 1, wherein the first diamond-like carbon film has a hardness of 10 to 40 GPa and a film thickness of 1 to 10 µm. The stamper-shaped mold for stamping an information recording disc according to claim 1, wherein the second diamond-like carbon film has a hardness of less than 10 GPa and a film thickness of 0.01 to 2 µm. 2. The stamper mold for forming an information recording disk coated with a diamond-like carbon film according to claim 1, wherein the amorphous silicon layer has a thickness of 5 to 100 nm. Place the mold on the cathode in the chamber and pump the chamber into a vacuum, Supplying a discharge gas to the chamber and high frequency discharge of the discharge gas to dry clean the surface of the mold, Supplying SiH ₄ to the chamber and discharging at a high frequency to coat an amorphous silicon (Si) layer on the surface of the mold, The hydrocarbon compound is supplied to the chamber and subjected to high frequency discharge to coat the first diamond-like carbon film on the amorphous Si layer formed on the mold, and the second diamond-like carbon film having a lower hardness is coated on the first diamond-like carbon film. Stamper-shaped now manufacturing method for forming a diamond-shaped carbon film coated information recording disk comprising a step. 6. The method of claim 5, wherein the dry washing step is performed at a pressure of 4 mTorr and a high frequency power density of 8 W / cm ² . 6. The method of claim 5, wherein the amorphous silicon layer coating step is performed at a pressure of 20 mTorr and a high frequency power density of 0.3 W / cm ² . The method of claim 5, wherein the first and second diamond-like carbon film coating step is a diamond-like carbon film made under the conditions of pressure 10 mTorr, temperature 20 ℃ ~ 50 ℃, high frequency power density of 0.05 ~ 1.5 W / cm ² Manufacturing method of stamper mold now for forming coated information recording disc. The method of claim 5, wherein the hydrocarbon compound is any one of benzene, methane, ethane, and acetylene. 6. The method of claim 5, wherein the discharge gas is argon (Ar).