JPH06187673A - Stamper for producing optical disk and its production - Google Patents

Abstract

PURPOSE:To prevent foreign matter such as dust from affecting the front side of a stamper even if the foreign matter gets between the rear side of the stamper and a metal mold. CONSTITUTION:A three-layered structure consisting of 1st, 2nd and 3rd layers 2, 3, 4 of materials different from each other in hardness from the surface is imparted to a stamper 1. The material of the 2nd layer 3 is harder than that of the 3rd layer 4. When the stamper 1 is fitted to a molding machine, even if foreign matter gets between the rear side of the stamper 1 and a metal mold on the fitting side, the relatively soft 3rd layer 4 absorbs the foreign matter, the relatively hard 2nd layer 3 acts as a barrier and the foreign matter is prevented from affecting the 1st layer 2 or the front side of the stamper 1 without considerably increasing the thickness of the stamper 1.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a stamper for manufacturing an optical disk and a manufacturing method thereof.

[0002]

2. Description of the Related Art Generally, this type of stamper is made of a single material such as nickel. Explaining the outline of the manufacturing process, first, a surface conductive treatment (nickel sputtering) is performed on a glass master after exposure and development to form a nickel film. Then, the thickness of the stamper is increased to about several 100 μm by nickel electroforming. After that, a mirror polishing step on the back surface, a glass master disc removing step, a resist removing step, and an outer diameter / inner diameter cutting step are performed to complete an optical disk manufacturing stamper.

[0003]

However, in the case of using such a stamper, in injection molding, foreign matters such as dust and dust enter between the stamper rear surface and the stamper mounting side mold, and the influence appears on the stamper surface. Sometimes.

Generally, since the mold is harder than the stamper, foreign matters such as dust are caught by the pressure at the time of injection molding on the stamper side. Here, when the stamper is sufficiently thick, the influence on the stamper surface can be ignored, but in the case of a typical stamper having a thickness of about several hundreds of μm, the stamper surface may be deformed into a convex shape. . Such deformation of the stamper not only causes a product defect of the disk to be manufactured, but also causes a problem that the stamper itself cannot be used.

[0005]

According to a first aspect of the present invention, a first layer, a second layer, and a third layer made of materials having different hardness are sequentially provided from the stamper surface side, and at least the second layer is provided. The stamper has a three-layer structure formed of a material harder than the three layers.

In this case, in the second aspect of the invention, the second layer is formed of bright nickel having a Vickers hardness in the range of 300 to 400 Hv, and in the third aspect of the invention.
The layer is made of pure copper having a Vickers hardness in the range of 100 to 150 Hv, and in the invention according to claim 4, the hardness of the third layer is made sufficiently smaller than the hardness of the mounting side die.

As a method of manufacturing such a stamper for manufacturing an optical disk, in the invention according to claim 5, a three-step electroforming process in which three kinds of electroforming liquids having different hardness are sequentially used,
The first layer, the second layer, and the third layer are sequentially provided from the front surface side of the stamper to manufacture a stamper for manufacturing an optical disc having a three-layer structure in which at least the second layer is harder than the third layer.

At this time, in the invention according to claim 6, the glass master is peeled off after the completion of the three-step electroforming process.

According to the seventh aspect of the invention, a mirror polishing step for the back surface of the stamper is provided between the electroforming step for the first layer and the electroforming step for the second layer.

[0010]

According to the first aspect of the present invention, there is provided a three-layer structure made of materials having different hardness, the third layer on the back side of the stamper.
Since the second layer, which is the intermediate layer, is harder than the layer, even if foreign matter is caught between the back surface of the stamper and the mold on the mounting side, the softer third layer absorbs the foreign matter and the harder second layer acts as a barrier. Therefore, the influence on the first layer or the surface can be prevented as much as possible without increasing the thickness of the stamper, and the stamper failure can be reduced.

According to the second aspect of the present invention, the second layer to be made hard is formed of bright nickel having a Vickers hardness in the range of 300 to 400 Hv, so that it is sufficiently hard while utilizing a general nickel stamper manufacturing process. Can be any layer.

According to the third aspect of the present invention, the third layer located on the back surface is formed of pure copper having a Vickers hardness in the range of 100 to 150 Hv, so that the electroforming step is performed as in a general nickel stamper. Available and
A sufficiently soft layer can be obtained, and since the thermal conductivity is high, the temperature control between the stamper and the mold becomes smooth.

In the invention according to claim 4, since the hardness of the third layer located on the back surface is sufficiently smaller than the hardness of the mounting side die, the die is less likely to be damaged and the life of the die is reduced. It will grow.

According to the fifth aspect of the invention, a stamper having a three-layer structure is manufactured by a three-step electroforming process in which three kinds of electroforming liquids are sequentially used, so that an electrode mounting portion for an electroforming bath, etc. Can be standardized, and can be manufactured at low cost and with high efficiency.

According to the sixth aspect of the invention, since the glass master is not peeled off during the electroforming process of three steps, it is possible to prevent foreign matter from entering the surface of the stamper.

According to the invention of claim 7, there is a mirror polishing step for the back surface of the stamper between the electroforming step for the first layer and the electroforming step for the second layer. Therefore, the first layer and the second layer are formed. The interface with and becomes flat, and a stamper with more excellent smoothness can be manufactured.

[0017]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described with reference to the drawings. The stamper 1 for manufacturing an optical disk according to the present embodiment basically has a three-layer structure in which a first layer 2, a second layer 3 and a third layer 4 are sequentially laminated as shown in FIG. Here, the stamper surface is on the side of the first layer 2, and the minute irregularities 5 for transfer are formed on the surface of the first layer 2. In such a three-layer structure, in this embodiment, each of the layers 2, 3 and 4 is formed of a material having different hardness, and the hardness is as follows: second layer 3> first layer 2> third layer 4. It is set to a size relationship.

More specifically, the first layer 2 is made of a nickel material having a Vickers hardness of 200 to 300 Hv, and the second layer 3 is made of nickel.
Is a bright nickel material having a Vickers hardness of 300 to 400 Hv, and the third layer 4 has a Vickers hardness of 100 to 150.
It is made of pure copper material in the Hv range. The bright nickel for the second layer 3 is a mixture of nickel and impurities,
Various variations can be obtained. Further, the copper for the third layer 4 is softer than nickel and can be formed by electroforming like nickel. The hardness of the third layer 4 must be sufficiently small (soft) with respect to the hardness of the mold so as not to damage the mold.

The stamper 1 having a three-layer structure having such hardness distribution has an advantage that it is hardly affected by foreign matter. The principle is shown in FIG. Stamper 1
The third layer 4 on the back side is mounted on the mounting side mold 6 of the molding machine to be used for optical disk production by injection molding. When mounting on the mounting side mold 6, as shown in FIG. Even if a foreign matter 7 such as dust enters between the stamper 1 and the stamper 1, a soft third layer 4 exists under the hard second layer 3 as shown in FIG. It will be taken in and absorbed inside. The arrow in the figure indicates the strain direction that occurs during uptake and absorption. Therefore, even if the stamper 1 has a normal thickness, the surface of the first layer 2 or the fine irregularities 5 is hardly deformed into a convex shape due to the influence of the foreign matter 7.

A method of manufacturing the stamper 1 will be described with reference to FIGS. 3 and 4. In the case of the conventional nickel stamper, the nickel electroforming process is basically the main component, but in producing the stamper 1 of this embodiment, a bright nickel electroforming process and a copper electroforming process were added. It is manufactured through a three-step electroforming process.

First, as shown in FIG. 3A, there is prepared a glass master disk 10 on which exposure / development has been completed and fine irregularities 9 have been formed by the resist 8. Next, as shown in FIG. 3B, a surface conductive treatment is performed to form a nickel film 11 by nickel sputtering on the developing surface of the glass master 10. Next, as shown in FIG. 3C, a nickel electroforming process is performed using a nickel electroforming solution to form the first layer 2 of nickel. After forming the first layer 2, as shown in FIG.
A bright nickel electroforming process is performed on the back surface side of the first layer 2 to form the second layer 3 of bright nickel. On this occasion,
The first layer 2 is used as a conductive layer. The bright nickel electroforming may be performed by mixing various organic brightening agents in a nickel electroforming bath. As a general theory, bright nickel has characteristics that the crystals are fine and the hardness increases. After the second layer 3 is formed, a copper electroforming step is performed on the back surface side of the second layer 3 to form the third layer 4 of pure copper, as shown in FIG.

After that, a polishing process is performed on the back surface of the stamper 1, a glass master 10 and a resist peeling process are performed as shown in FIG. 3F, and finally, an outer diameter / inner diameter cutting process of the stamper 1 is performed. Therefore, as shown in FIG.
The layered stamper 1 is completed. That is, since it is basically formed by sequentially performing the three-step electroforming process, it is possible to share the electrode mounting portion and the like to the electroforming bath and to manufacture at low cost. Further, since the glass master 10 is not peeled off in the middle of each electroforming step, and the glass master 10 is peeled off in the final step, it is possible to prevent foreign matters and the like from entering the surface side as much as possible. That is, when mirror-polishing the back surface in a later step, it is better to keep the glass master 10 in close contact until the end in order to prevent foreign substances such as abrasives that cause defects from entering the stamper surface. is there.

If a mirror polishing step for the back surface of the stamper (back surface of the first layer) at that stage is added between the nickel electroforming step and the bright nickel electroforming step, the first layer 2 and the second layer to be formed will be formed. Since the interface with the two layers 3 becomes extremely flat, the stamper 1 having more excellent flatness can be obtained.

[0024]

According to the first aspect of the invention, the stamper structure has a three-layer structure made of materials having different hardness, and the second layer which is the intermediate layer is harder than the third layer on the back side of the stamper. Therefore, even if foreign matter is caught between the back surface of the stamper and the mold on the mounting side, the soft third layer absorbs the foreign matter,
Since the harder second layer serves as a barrier, the influence on the first layer or the surface can be prevented as much as possible without increasing the stamper thickness, and the occurrence of stamper failure can be reduced.

According to the second aspect of the present invention, since the second layer to be hardened is made of bright nickel having a Vickers hardness of 300 to 400 Hv, it is generally sufficiently hard while utilizing the nickel stamper manufacturing process. Can be any layer.

According to the third aspect of the present invention, the third layer located on the back surface is formed of pure copper having a Vickers hardness of 100 to 150 Hv. Therefore, the electroforming step is performed as in the case of a general nickel stamper. A layer that can be used and is sufficiently soft is obtained, and since the thermal conductivity is high, the temperature control between the stamper and the mold becomes smooth.

According to the invention of claim 4, since the hardness of the third layer located on the back surface is made sufficiently smaller than the hardness of the die on the mounting side, the die is less likely to be scratched. The life can be extended.

According to the fifth aspect of the invention, the stamper having a three-layer structure is manufactured by a three-step electroforming process in which three kinds of electroforming liquids are sequentially used. The mounting portion and the like can be made common, and the manufacturing can be performed at low cost and with high efficiency.

According to the sixth aspect of the invention, since the glass original plate is not peeled off during the three-step electroforming process, foreign matter is prevented from entering the stamper surface and the occurrence of defects is reduced as much as possible. You can

According to the invention of claim 7, a mirror polishing step for the back surface of the stamper is added between the electroforming step for the first layer and the electroforming step for the second layer. The interface with the two layers becomes flat, and a stamper having more excellent smoothness can be manufactured.

[Brief description of drawings]

FIG. 1 is a sectional structural view of a stamper showing an embodiment of the present invention.

FIG. 2 is a cross-sectional structural view showing the principle of the effect of foreign matter mixing.

FIG. 3 is a cross-sectional view showing a stamper manufacturing process in order.

FIG. 4 is a block diagram sequentially showing a manufacturing process.

[Explanation of symbols]

 1 Stamper 2 1st Layer 3 2nd Layer 4 3rd Layer 6 Mounting Side Mold 10 Glass Master

Claims (7)

[Claims] 1. A first layer, a second layer, and a third layer made of materials having different hardness are provided in order from the stamper surface side, and at least the second layer is made of a material harder than the third layer.
A stamper for manufacturing an optical disc, which has a layered structure. 2. The second layer has a Vickers hardness of 300 to 4
The stamper for manufacturing an optical disc according to claim 1, wherein the stamper is formed of bright nickel within a range of 00Hv. 3. The third layer has a Vickers hardness of 100-1.
The stamper for manufacturing an optical disk according to claim 1 or 2, wherein the stamper is made of pure copper within a range of 50 Hv. 4. The stamper for manufacturing an optical disk according to claim 1, wherein the hardness of the third layer is made sufficiently smaller than the hardness of the mounting die. 5. A first layer, a second layer and a third layer are provided in order from the stamper surface side by a three-step electroforming process in which three kinds of electroforming liquids having different hardness are sequentially used, and at least the second layer is formed. A stamper manufacturing method, characterized in that a stamper for manufacturing an optical disc having a three-layer structure of which the layer is harder than the third layer is manufactured. 6. The stamper manufacturing method according to claim 5, wherein the glass master is peeled off after completion of the three-step electroforming process. 7. The stamper manufacturing method according to claim 5, further comprising a mirror polishing step for the back surface of the stamper between the electroforming step for the first layer and the electroforming step for the second layer.