JPH01165053A - Method for forming stamper for reproducing optical disk - Google Patents

Abstract

PURPOSE:To simultaneously obtain two stampers from one substrate, to attain a cost down and to improve a planeness hardly difficult to produce a deformation such as the curvature of the substrate by executing various processings simultaneously on both the surfaces of a glass substrate and forming the stamper. CONSTITUTION:Photoresists 2a, 2b are is applied to both-face of the glass substrate 1, a laser exposure is carried out at every face to form a fine rugged form and apply conductive coats 3a, 3b. Ni electro casts 4a, 4b are formed thereon, Al disks 5a, 5b are lined by room temperature curing adhesives 6a, 6b, completely cured, thereafter, removed to obtain the two stampers. Ultraviolet cured resins 7a, 7b are applied on the washed stamper, to mount acrylic plates 8a, 8b, removed from the stamper after curing by the projection of the ultraviolet ray, recording materials are applied on surfaces, the surfaces are opposed through a spacer to obtain an air sandwich type optical disk 11.

Description

DETAILED DESCRIPTION OF THE INVENTION Technical Field The present invention relates to a method for producing an optical disk duplication stamper for optical disks such as laser disks and compact disks.

BACKGROUND OF THE INVENTION Generally, this type of optical disk is manufactured using the so-called 2P method, in which a stamper is coated with an ultraviolet curing resin and then irradiated with ultraviolet rays. To create a stamper for this purpose, first, a photoresist is applied to one side of a glass substrate, a fine unevenness is formed by photolithography, a conductive film is formed thereon, and then Ni electroforming is performed. However, after such Ni electroforming process, glass and N
Since the coefficient of linear expansion is different from that of Ni, the difference generates tensile stress in the electroformed Ni, pulling the glass substrate and causing warping.

Therefore, conventionally, the flatness of the glass substrate has been corrected by bonding an aluminum plate or the like to the glass substrate using an adhesive or the like and backing the glass substrate.

However, even with this kind of lining, the flatness can be reduced to 30
It is not possible to correct the condition to a level smaller than μm.

For this reason, the conventional stamper manufacturing method causes non-uniformity in the thickness of the ultraviolet curable resin and non-uniformity in the thickness of the recording material, resulting in large variations in the signal values obtained.

In other words, it is extremely difficult to produce a high-quality optical disc.

the purpose .

The present invention has been made in view of the above points, and provides a method for manufacturing a stamper for optical disk duplication, which can easily and inexpensively manufacture a high-quality stamper with good flatness without causing warping of the glass substrate. The purpose is to provide.

Structure In order to achieve the above object, the present invention includes a step of applying a photoresist to both sides of a glass substrate, a step of exposing both sides of the glass substrate coated with a photoresist film with a laser beam, and a step of applying a laser beam to the glass substrate after exposure. A step of applying a conductive film to both sides of the glass substrate, a step of electroforming Ni on both sides of the glass substrate to which the conductive film has been applied, and a step of lining the Ni electrodeposited surfaces of both sides of the Ni electroformed glass substrate. It is characterized by:

Hereinafter, one embodiment of the present invention will be described based on the drawings. First, as shown in FIG. 1(a), a glass substrate 1 is prepared,
As shown in the same figure (b), photoresist 2a is applied on both sides.
, 2b. After pre-baking, one side is exposed to laser light to form fine irregularities in the photoresist 2a as shown in FIG. 2(C). After single-sided exposure, flip the glass substrate 1 over and apply the photoresist 2.
Laser exposure is similarly performed on the b side to form fine irregularities on the photoresist 2b as well. By such double-sided laser exposure, a glass substrate 1 as shown in FIG. 2(d) is obtained. Actually, the uneven shape is formed by development and post-baking treatment after exposure.

Next, as shown in FIG. 3(e), conductive coatings 3a and 3b are applied to both surfaces, and the conductive coating 3a.

Ni electroforming is performed on the stampers 3b to form stampers 4a and 4b as shown in FIG. 3(f). Then, the Ni electrodeposited surfaces on both sides are lined with AΩ disks 5a and 5b with room temperature curing adhesives 6a and 6b, as shown in FIG. 2(g). This adhesive 6a.

After the stamper 6b is completely cured, the stampers 4a, 4b (Afl disk plate 5a) are applied to both sides of the glass substrate 1.

5b is also integral). In this way, two stampers 4a and 4b are obtained from one glass substrate 1, as shown in FIG. 4(h).

In this state, after removing the residual photoresist by ashing with a solvent and oxygen plasma, the ultraviolet curing resin 7a is applied to the surfaces of the stampers 4a and 4b as shown in FIG.
. As a result, the ultraviolet curing resins 7a and 7b are completely cured, and the fine irregularities on the stampers 4a and 4b are transferred. Then, the ultraviolet curing resin 7a is obtained by curing the acrylic plates 8a and 8b from the stampers 4a and 4b.

After peeling off together with 7b, recording materials 9a and 9b are applied to the surface as shown in FIG. 7(j). After this, the same figure (h)
As shown in FIG. 9, recording materials 9a, 9. An air sandwich type optical disk 11 is obtained by facing each other with the spacer 10 interposed therebetween, with the b side as the inner surface.

Regarding the optical disc 11 manufactured in this way, RF
When evaluated using signal and TE scratch signal drive,
The characteristics shown by plotting white circles in FIG. 2 were obtained. That is, even if the radial position of the optical disc 11 changes, the reflectance of the land remains almost constant. Incidentally, the characteristics plotted with triangles in the same figure are the characteristics of the optical disk manufactured by the Juto method, and it can be seen that there are variations in reflectance.

Prior to such measurements, the thickness of the transferred ultraviolet curing resin was measured using the method of this embodiment and the conventional method, and the results shown in Figure 3 were obtained (the white circles indicate the original Examples).

As described above, according to this embodiment, two stampers 4a and 4b can be produced simultaneously from one glass substrate 1, and therefore costs can be reduced (conventionally, it is 1:1). In addition, various treatments for producing a stamper are performed on both sides of the glass substrate 1 to ensure balance, so that warping or the like is less likely to occur in the glass substrate 1. Therefore, the resulting stamper 4a , 4
b also has good flatness. As a result of the second result, the thickness of the ultraviolet curable resin on the disk to be duplicated is also made uniform, and the variation in signal values on the obtained optical disk becomes small.

Effects In the present invention, as described above, various treatments are performed on both sides of the glass substrate to produce a stand bar.
Two stampers can be obtained from one glass substrate at the same time, reducing costs.Double-sided processing provides a good balance, making it difficult for the glass substrate to warp or otherwise deform. It can be made to have good flatness and can be used for good duplication of optical discs.

[Brief explanation of the drawing]

The drawings show one embodiment of the present invention. Fig. 1 is a sectional view showing the process order, Fig. 2 is a radial position-land reflectance characteristic diagram showing a comparison with the conventional method, and Fig. 3 is the conventional method. FIG. 3 is a radial position--thickness characteristic diagram of ultraviolet curing resin shown in comparison with FIG. 1... Glass substrate, 2a, 2b... Photoresist, 3a, 3b... Conductive coating, 5a, 5b... Lining Applicant Ricoh Co., Ltd. -3Z space + diameter (r + tm) - Size anal turtle ml-

Claims (1)

[Claims] A step of applying a photoresist to both sides of a glass substrate, a step of exposing both sides of the glass substrate coated with a photoresist film to a laser beam, a step of applying a conductive coating to both sides of the exposed glass substrate, A method for producing a stamper for optical disk duplication, comprising the steps of electroforming Ni on both sides of a glass substrate provided with a conductive film, and lining the Ni electrodeposited surfaces on both sides of the electroformed glass substrate. .