JPH08335335A - Electroforming device of stamper for optical disk - Google Patents

Abstract

PURPOSE: To stably form a stamper for optical disks having high accuracy. CONSTITUTION: This electroforming device has a nozzle 4 opened with plural injection ports 4-1 (i=1, 2,...n) for injecting an electroforming liquid in a direction perpendicular to a master disk 6 formed with a conductive metallic film between an anode 3 of an electroforming metal and a cathode 2 set with the master disk 6 within an electroforming main vessel 1 in which the electroforming liquid 7 is housed. The opening areas of these injection ports 4-1 are set successively larger from the center of the master disk 6 toward the outside end. The electroforming liquid injected to the master disk 6 is so injected as to be made uniform when the cathode 2 rotates around a shaft 2a, by which the electric lines of force are made uniform and the thickness of the electroforming film is made uniform.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electroforming apparatus for stampers for optical discs, and more particularly to an electroforming apparatus for making a replica of an optical information recording medium with a highly precise thickness. The apparatus is used in the industrial field such as precision electroforming surface treatment.

[0002]

2. Description of the Related Art Optical discs, which are products utilizing laser light capable of forming minute spots, have uniform technical specifications worldwide and are highly convenient for both users and producers. It is expanding. Further, due to the diversification of needs, the information density stored in the optical disc is rapidly increasing. In order to increase the information density, not only the optical technology but also the precision of the optical disc itself is required, and accordingly, the precision and processing of the stamper for replica manufacturing the optical disc are required to be rationalized.

The stamper is obtained by precisely polishing a glass master plate, finishing it to a flat and high surface roughness, and coating a photoresist on the polished glass substrate by spin coating so that the photoresist has a constant thickness, and then baking it. Done,
After this is exposed by a laser beam modulated corresponding to information, development is carried out to form a fine concavo-convex shape according to information by the photoresist layer. A conductive Ni film is formed on the upper surface of the fine concavo-convex shape by a film forming method such as a sputtering method or a vacuum evaporation method, and a Ni electroformed layer is further formed on the conductive Ni film. A stamper is obtained by peeling. in this way,
The thickness of the formed electroformed layer is an important factor that defines the accuracy of the stamper.

The Ni electroformed layer uses a substrate coated with a conductive Ni film as a cathode and reduces Ni ions produced in an electroforming solution in an electroforming bath in which Ni for electroforming is used as an anode. It is known that the thickness of the electroformed layer becomes non-uniform when the density of the lines of electric force during electroforming is not constant. As means for solving this, Japanese Patent Laid-Open No. 7-64
No. 13 discloses an electroforming apparatus and an electroforming method for a stamper for manufacturing an optical recording medium.

In the stamper electroforming method disclosed in Japanese Patent Laid-Open No. 7-6413, a circular opening having a diameter smaller than the effective portion of the master is provided in the gap between the anode and the cathode of the electroforming apparatus, and the opening is formed around the opening. A baffle plate having small holes with a diameter smaller than that of the portion or a baffle plate having a variable opening diameter is provided, and the stamper is electroformed while the diameter of the opening is changed.

Generally, electric lines of force at the time of electroforming are more likely to be concentrated on the peripheral end portion than the central portion, and the film thickness at the peripheral end portion is thicker accordingly. By providing a circular opening whose diameter is smaller than the effective part of, the electric force lines at the outer end are blocked, and the electric force lines on the master are made constant,
This is intended to make the thickness of the electroformed layer uniform.

[0007]

However, the baffle plate used in the above-mentioned method of the prior art is provided with an opening for controlling the film thickness, and the shape of the opening is selected to control the film thickness. However, even with this method, the tendency of the thickness of the electroformed film to increase from the center of the opening to the peripheral portion cannot be prevented, and in order to obtain a uniform electroformed film thickness distribution, the opening distribution of the opening is It is practically difficult to make fine adjustments for managing the film thickness distribution, such as changing the opening area and adjusting the electric current with the lapse of electroforming.

The present invention solves the above-mentioned problems of the prior art, the electroformed film thickness of the stamper is uniform with no difference between the inner and outer circumferences, and the condition of the electroformed film thickness can be easily controlled. Furthermore, it is an object of the present invention to provide an electroforming apparatus that can obtain a stable electroformed film thickness and a stable and highly accurate stamper with improved surface roughness.

[0009]

[Means for Solving the Problems]

(1) In an electroforming apparatus for forming a conductive Ni coating on the upper surface of a fine uneven shape of a track groove provided in a photoresist layer on a glass substrate and performing Ni electroforming on the conductive Ni coating, A cylindrical nozzle having a plurality of injection ports for ejecting an electroforming liquid in a direction substantially perpendicular to the Ni coating film is arranged in the radial direction of the glass substrate, and the injection ports are provided from the central portion to the peripheral end portion of the substrate. And (2) in (1) above, the nozzle provided with the plurality of injection ports has an opening / closing mechanism capable of changing the opening area of the injection ports. In (1) or (2) above, (3) two or more nozzles provided with the plurality of injection ports are combined.

[0010]

When the electroforming liquid is jetted perpendicularly to the surface from the semi-rearwardly-opened master onto the rotating cathode-side electroconductive Ni-coated master, the sprayed electroforming liquid is evenly distributed on the master surface. The opening area of the injection port is gradually increased from the center to the peripheral end side so that the electric power line density is kept constant and the electroformed film thickness is made uniform.

[0011]

【Example】

[Embodiment 1] (corresponding to claim 1) FIG. 1 is a view for explaining an electroforming apparatus for an optical disk stamper according to the present invention. FIG. 1A is a side sectional view of the electroforming apparatus. 1B is a cross-sectional view taken along the line AA of FIG. 1A, in which 1 is an electroforming main tank, 2 is a cathode, 3 is an anode, 4 is a nozzle, 5 is a baffle plate, and 6 Is a master, and 7 is an electroforming liquid.

The electroforming apparatus shown in FIG. 1 (A) has an electroforming liquid 7
A plate-shaped anode 3 made of an electroformed metal Ni electrode material is attached to an electrocasting main tank 1 for accommodating an electroformed metal, and the anode 3 is made of an annular insulating material for controlling electric lines of force at a peripheral end portion. Buckle plate 5
Are joined. Further, a plate-shaped cathode 2 is attached in parallel with the anode 3 so as to be rotatable around an axis 2a, and a master 6 having a Ni conductive film formed on the surface of the cathode 2 facing the anode 3 is set. ing. Between the anode 3 and the cathode 2, a cylindrical nozzle 4 which is substantially parallel to each surface and has a closed tip is provided penetrating the bottom of the electroforming main tank 1. The nozzle 4 discharges the electroforming liquid in a direction perpendicular to the master 6, and has a plurality of injection ports 4 _-1 , -4- _i , -4- _{n in} the radial direction from the center of the master 6 to the outer periphery. Open at equal intervals.

As shown in FIG. 1 (B), the opening areas of the injection ports 4 _-1 , 〜 4 _-i , 〜 4 _-n gradually increase from the center of the master 6 to the outer periphery, and this size is the same. The relationship is selected so that the amount of electroforming liquid sprayed onto the master 6 rotating with the cathode 2 is uniform over the entire area of the master 6. If the areas of the injection ports are equal, the discharge amount of the electroforming liquid injected onto the rotated master 6 decreases from the center toward the peripheral edge.

When the master 6 is rotated, the injection port 4 becomes 1
Comparing the area of the rotary master 6 scanned by the individual pieces with the area S ₁ from the center radius r ₁ to r ₁ ′ and the radius r ₂ to r ₂ ′ of the peripheral edge, S ₁ = π (r ₁ ′ ² −r ₁ ² ) S ₂ = π (r ₂ ′ ² −r ₁ ² ), and since S ₂ > S ₁ , if the area of the injection port in the central portion is the same as that in the outer peripheral portion, each unit The discharge amount of the electroforming liquid per area decreases on the outer peripheral side. On the other hand, by making the opening area of the jet port on the peripheral end side larger than the opening area on the central side and selecting the opening area at a ratio corresponding to, for example, 1,5S ₂ > S ₁ , The discharge amount of the electroforming liquid is increased and the electroforming liquid is uniformly discharged over the entire area of the master 6.

According to the first embodiment, since the electroforming liquid is evenly applied to the discharge surfaces of the central portion and the peripheral end portion of the master 6, the lines of electric force can be made uniform and the precision of the electroformed film thickness can be improved.

[Second Embodiment] (Corresponding to Claim 2) FIG. 2 is a view for explaining a second embodiment of the electroforming apparatus for an optical disk stamper according to the present invention, and FIG. 2B is a front view of the nozzle as seen from the injection port side, in which 10 is a nozzle and 11 and 12 are opening and closing plates.

The nozzle 10 which is closed in FIG.
Of the injection port 10 on the tip side of
_-1 is an example having an open wall of the nozzle 10 to a square, the opening 10 in _-1, opening rotates in the circumferential direction along the wall surface 10
The opening / closing plates 11 and 12 for adjusting the opening area of _-1 are provided. As shown in FIG. 2B, by rotating the opening / closing plates 11 and 12, the opening area is adjusted so as to be gradually increased toward the peripheral end portion of the master 6. The opening shape is not limited to the quadrangular shape, and the opening / closing plates 11 and 12 may be opened or closed individually or in combination with a plurality of injection ports.

According to the second embodiment, since the area of the injection port can be arbitrarily adjusted, the injection amount of the electroforming liquid can be freely adjusted, and the thickness of the electroformed film can be easily controlled.

FIG. 3 is a view for explaining a third embodiment of the electroforming apparatus for optical disk stampers according to the present invention.
3A is a side sectional view of an electroforming apparatus, FIG. 3B is a plan view of a nozzle, in which 8 is an electroforming liquid flow tube, 20, 21, 22, 2
Reference numeral 3 is a nozzle, and a portion having the same function as in FIG.
The same reference numerals as in FIG. 1 are attached.

The nozzle according to the third embodiment is an example in which two or more nozzles are provided. In FIG. 3 (B), the nozzles 20, 21,
In the case where four nozzles 22 and 23 are provided, they are arranged in a cross shape on the same plane. Each injection port 20
_-i , 21 _-i , 22 _-i , 23 _-i (i = 1, 2, ..., n) is
As in the case of the nozzle 4 shown in FIG. 1 (B), the area gradually increases from the central portion toward the outer end portion, and the electroforming liquid common to each nozzle is provided in the central portion where the nozzles intersect. An electroforming liquid flow pipe 8 for supplying is provided. Electroformed flow tube 8
3A penetrates through the central portion of the anode 3 at a right angle as shown in FIG. 3A, and is indicated by an arrow from the injection ports 20 _-i , 21 _-i , 22 _-i , 23 _-i toward the master 6. Is sprayed at a right angle.

In the third embodiment, the amount of electroforming liquid ejected increases in proportion to the number of nozzles and is evenly ejected, so that the gas adhering to the master, for example, hydrogen gas generated at the cathode is effectively removed. As a result, the surface roughness of the electroformed film is reduced and a flat surface is obtained.

[0022]

As is apparent from the above description, the present invention has the following effects. (1) Effect corresponding to claim 1: Since the nozzle having an injection port for ejecting the electroforming liquid is provided and the opening area of the injection port is increased from the central portion of the master toward the peripheral end, the cathode (master) rotates. At this time, the electroforming liquid is evenly applied to the injection surfaces of the central portion and the peripheral edge portion, and the lines of electric force can be made uniform to improve the accuracy of the film thickness. (2) Effect corresponding to claim 2: Since the injection port of the nozzle with an injection port of claim 1 is provided with a function that can be opened and closed, the injection amount of the electroforming liquid can be freely adjusted by opening and closing the injection port. Therefore, the film thickness can be easily controlled and various film thickness conditions can be dealt with. (3) Effect corresponding to claim 3: Since the number of nozzles having the mechanism of claim 1 or 2 is two or more, the number of injection ports is increased and the injection amount of electroforming liquid is increased in proportion thereto, and further, Can be sprayed evenly on the master. As a result, it is possible to effectively remove the gas adhering to the master and prevent the formation of protrusions and dents in the electroformed film, and it is possible to form electroformed with more improved surface roughness. The effect that the time required for polishing can be shortened and the manufacturing cost can be reduced.

[Brief description of drawings]

FIG. 1 is a diagram for explaining an electroforming apparatus for an optical disk stamper according to the present invention.

FIG. 2 is a diagram for explaining a second embodiment of an electroforming apparatus for an optical disk stamper according to the present invention.

FIG. 3 is a view for explaining a third embodiment of the electroforming apparatus for an optical disk stamper according to the present invention.

[Explanation of symbols]

1 ... Electroformed main tank, 2 ... Cathode, 3 ... Anode, 4 ... Nozzle, 5 ...
Baffle plate, 6 ... Master, 7 ... Electroforming liquid, 10 ... Nozzle, 1
1, 12 ... Open / close plate, 8 ... Electroforming liquid flow tube, 20, 21,
2, 23 ... Nozzles.

Claims (3)

[Claims] 1. An electroforming apparatus for forming a conductive Ni coating on the upper surface of a fine uneven shape of a track groove provided in a photoresist layer on a glass substrate and performing Ni electroforming on the conductive Ni coating, Cylindrical nozzles having a plurality of injection ports for ejecting the electroforming liquid in a direction substantially perpendicular to the conductive Ni coating are arranged in the radial direction of the glass substrate, and the injection ports are surrounded by the central portion of the substrate. An electroforming device for an optical disk stamper, characterized in that the opening area is gradually increased toward the end. 2. The electroforming apparatus for an optical disk stamper according to claim 1, wherein the nozzle provided with the plurality of ejection ports has an opening / closing mechanism capable of changing the opening area of the ejection ports. 3. The electroforming apparatus for an optical disk stamper according to claim 1, wherein two or more nozzles provided with the plurality of ejection ports are combined.