JPH04345934A - Production of stamper for optical disk - Google Patents

Abstract

PURPOSE:To facilitate the stable and mass production of the stampers having good character transferability and uniform groove characteristics by providing continuous grooves at the time of forming characters for recognition on the stampers, thereby enhancing the flowability of a resin at the time of forming optical substrates. CONSTITUTION:A resist film 2 is deposited on an optically polished glass substrate 1 and is subjected to laser cutting to form fine rugged patterns having, for example, 1.6mum inter-groove spacing and 0.1mum strength in a 6 to 118mm diameter range. This range is used as a symbol recording region. The entire surface inclusive of this range is coated with a conducting film 3 and an Ni plating layer 4 is formed by a plating method thereon, by which the stamper 5 is produced. Prescribed pulse modulation signals are recorded to the patterns of the recording region in such a manner and the characters for identification of 10 characters are constituted of the spirally continuous grooves while these grooves are arrayed on the same circumference within the range of 40 to 44mm diameter off the recording region. In addition, the beam of the light intensity varying with the character parts and the part where there are no characters is used.

Description

[Detailed description of the invention]

0001

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

0002

2. Description of the Related Art There are two conventional methods for manufacturing character portions of stampers for optical discs: a method using a light beam and a method using machining.

In the first method, a positive photoresist is coated on an optically polished glass substrate, and a light beam is irradiated (in this case, (He--Cd laser was used.) After that, a development process is performed to obtain a desired uneven pattern.

[0004] In this case, the character area is divided into a part where the character exists, which is formed by irradiating the light beam, and a part where the character does not exist, which is formed by not irradiating the light beam.

The character formation area is formed in an area other than the signal recording area of the optical disc stamper.

[0006] Moreover, the characters are formed on the same circumference with a desired size and a desired spacing.

[0007] A conductive film of Ni is formed on the glass substrate, and then a film of about 300 μm is formed by electroforming plating.
A Ni plating layer is then formed. Next, the plated surface was polished to ensure a predetermined thickness of the plated layer, and the inner and outer diameters were finished to obtain a stamper with the desired character.

[0008] In the second method, a character is formed by machining an area other than the signal recording area of an optical disc stamper using a cutting tool (such as a milling cutter or drill).

[0009] In this case, high speed rotation (5000~1000
Machining is performed by pressing a cutting tool running at 0 rpm onto the stamper surface, and chips generated during machining are removed by cleaning after machining of the character portion is completed.

[0010] In this way, a stamper containing a desired character was obtained.

[0011]

[Problems to be Solved by the Invention] However, in the above-mentioned prior art, in the first method, an optical disc stamper having a character area and a signal recording area is used, and the area where the character exists and the area where the character exists are located on the same circumference. When molding the substrate of an optical disc using a stamper with a blank part, the signal characteristics of the signal recording area close to the area where characters exist and the signal characteristics of the signal recording area close to the area where no characters exist are different. It turned out that there is a difference.

This is a problem in that the shape of the groove changes slightly depending on the presence or absence of a character in the inner peripheral portion of the signal recording area of the optical disc substrate.

In addition to the problems of the first method described above, the second method also has the problem of a worsening of the error rate due to adhesion of chips generated during machining to the stamper.

Furthermore, there is a problem in that the stamper is deformed due to unreasonable stress being applied to the stamper due to changes in the sharpness of the cutting tool, processing conditions, etc.

SUMMARY OF THE INVENTION The present invention is intended to solve these problems, and its purpose is to provide a stamper that can form high-quality substrates even if characters are present on the stamper. It is in.

[0016]

[Means for Solving the Problems] In the method for manufacturing an optical disc stamper of the present invention, when adding a character pattern for recognition (hereinafter referred to as a character) to an area other than the signal recording area, a continuous spiral groove is formed. (hereinafter referred to as groove).

Furthermore, the character portion is characterized in that grooves are continuously formed using light beams of different light intensities.

[0018]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a diagram showing the state of character formation according to the present invention. FIG. 2 is a partially enlarged view of FIG. 1. Figure 3
is a process explanatory diagram.

As shown in FIG. 3, a resist film 2 is formed on an optically polished glass substrate 1, and laser cutting is performed using a dedicated laser exposure device, so that the groove spacing is 1.6.
A fine uneven pattern with a depth of 0.1 μm and a diameter of 4
It is formed in the range of 6 mm to 118 mm. (This range is referred to as a signal recording area.) Next, a conductive film 3 is formed, and a Ni plating layer 4 is formed by a plating method to obtain a stamper 5.

The concavo-convex pattern in the signal recording area records a predetermined pulse-modulated signal, and in this case, the EF
A so-called CD signal modulated by M was used.

Regarding the stamper identification character in the present invention, the diameter of the character other than the above-mentioned signal recording area is 40 mm.
It was formed within the range of 44 mm to 44 mm. The number of characters at this time was 10, and they were lined up on the same circumference.

When forming the character, two types of feed pitch of the laser exposure device, 0.8 μm and 1.6 μm, were selected, and the rotation method was a CLV method with a constant linear velocity of 1.4 m/1.
The test was conducted by selecting two types: s and CAV method with a constant angular velocity of 900 rpm.

There are two light beams in the laser exposure device. Furthermore, it has the ability to arbitrarily adjust the interval between the light beams.

In the first method of the present invention, two light beams are used, and the interval between the two light beams is eliminated in advance.
Adjust so that they are on the same track, expose the character part with the first light beam, and make the second light beam follow the exposed part of the first light beam. Furthermore, exposure was performed by providing a difference in the light intensity of the first light beam and the light intensity of the second light beam. (In this case, the first beam was greater than the second beam.) In the second method of the present invention, one light beam was used. In this case, an appropriate amount of offset is set in advance for the light intensity with which the character is exposed. The necessary offset amount was set so that the light intensity could be maintained at about 0.5 times the light intensity of the character part. To set the offset amount, a new circuit board was added to the laser exposure device so that the desired light intensity could be obtained. (FIG. 4) Table 1 shows the results of the first method and the second method in the present invention.

[Table 1] Further, the groove formation state in the character portion was as shown in FIGS. 1 and 2.

[0025]

[Effects of the Invention] As described above, according to the present invention, the character portion is formed by a continuous spiral groove, and the character portion and the non-character portion are formed using light beams with different light intensities. After creating a stamper and manufacturing an optical disc substrate, we were able to find that the fluidity of the resin in the inner circumference of the signal recording area was uniform, resulting in good transferability and consistent groove characteristics. .

[Brief explanation of the drawing]

FIG. 1 is a character formation state diagram of the present invention.

FIG. 2 is a partially enlarged view of FIG. 1.

FIG. 3 is a process explanatory diagram.

FIG. 4 is a circuit diagram added in the embodiment of the present invention.

[Explanation of symbols]

1 Glass substrate 2 Resist 3 Conductive film 4 Plating layer 5 Stamper 6 Character 7 Groove

Claims (2)

[Claims] 1. When adding a character pattern (hereinafter referred to as a character) for recognizing the stamper to an area other than the signal recording area of an optical disc stamper,
A continuous spiral groove (hereinafter referred to as a groove)
A method for producing a stamper for an optical disc, characterized in that the stamper is formed by: 2. A method for producing a stamper for an optical disc, characterized in that, in the method for forming a character portion, grooves are successively formed using light beams having different light intensities.