JP3428064B2 - Manufacturing method of optical disk substrate - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing an optical disk substrate for manufacturing an optical disk stamper. 2. Description of the Related Art For example, an optical disk stamper used for manufacturing an optical disk, a magneto-optical disk or the like by the 2P method is manufactured according to the following procedure. First, as shown in a flowchart of FIG. 4, a glass substrate serving as a master is precision-cleaned in step ST101. Next, in step ST102, the glass substrate is baked. Subsequently, in step ST103, a resist is applied to one main surface of the glass substrate. After pre-baking the glass substrate in step ST104, signal information is laser-cut in step ST105. Next, development is performed in step ST106. As a result, the resist corresponding to the preformat data pattern is removed. Next, at step ST107, the temperature of 100 ° C.
Perform post-bake in 60 minutes. Then, step S
Electroless plating is performed in T108, and then in step ST1.
At 09, electroplating is performed. Next, after polishing the back surface of the glass substrate in step ST110, the stamper is peeled off from the glass substrate. Next, in step ST111, the resist adhering to the stamper is removed. As a result, step ST
At 112, a stamper is made. In order to regenerate the glass substrate in step ST113, Ni is removed in step ST114. Then, after alkali treatment in step ST115, polishing is performed in step ST116 to regenerate the glass substrate. The recycled glass substrate is placed in step ST10.
Returning to step 1, the above-described steps are sequentially repeated, and the process is again performed to manufacture a stamper. However, in the current process, the adhesion between the glass substrate and the resist is insufficient, and therefore, when the stamper is peeled off from the cut glass substrate (resist master). , The resist layer is destroyed,
There is a disadvantage that it adheres to the stamper. Therefore, a step of dissolving the resist adhering to the stamper with acetone or the like after peeling is required. As described above, according to the above-described manufacturing method, only one stamper can be manufactured from one glass substrate, which is extremely disadvantageous in mass-producing the stamper. (Steps ST101 to ST101)
Man-hours (steps up to step ST106) (about 3 days)
It takes. Accordingly, the present invention has been proposed in view of such a conventional situation, and is an optical disk substrate having high quality and excellent productivity which enables a plurality of stampers having the same characteristics to be manufactured from one master substrate. It is an object of the present invention to provide a method for producing the same. In order to achieve the above-mentioned object, the present invention provides a glass substrate on which signal information is recorded in advance by laser cutting, as a master substrate, and an optical disk by transfer from the master substrate. In the method of manufacturing an optical disc substrate for manufacturing a stamper, when forming the first stamper, the master substrate is subjected to ultraviolet irradiation and baking in an inert atmosphere after laser cutting and development, and then to chemical plating. A first stamper is obtained in the steps from pretreatment, chemical plating and electrolytic plating. Then, after the master substrate and the first stamper are separated, the master substrate is subjected to solvent cleaning, application of a protective film, removal of Ni plating, removal of the protective film, solvent cleaning, and baking. Then, in forming a stamper subsequent to the second stamper, the steps from the chemical plating pretreatment to which an acid is added to chemical plating, electrolytic plating, and separation of the master substrate and the stamper are repeated. In the present invention, when the master substrate subjected to the laser cutting and developing treatment is irradiated with ultraviolet rays, the photoresist is polymerized and polymerized. Subsequently, when this is baked, the adhesion between the glass and the resist increases. Therefore, even if the stamper is subsequently peeled off from the master substrate, the resist does not adhere to the stamper, and the master substrate can be reused several times. Embodiments of the present invention will be described below in detail with reference to the drawings. In the present embodiment, a manufacturing process of an optical disk substrate will be described with reference to a flowchart shown in FIG. In order to manufacture an optical disk substrate serving as an optical disk stamper, first, a disk-shaped glass substrate (220 mm in diameter) is precision-cleaned in step ST1. Specifically, IPA drying is performed after the silane treatment. Next, at step ST2, at 120.degree.
Glass baking is performed under the condition of 0 minutes. Next, in step ST3, a resist is applied to one main surface of the glass substrate. In applying the resist, since the baking after the irradiation of ultraviolet rays performed in the later-described step is quite hard at 200 ° C., the amount of photoresist thinning is taken into account, and the resist is applied slightly thicker. In the conventional method, the value is 103 ± 1 nm, but in the present embodiment, it is set to about 108 ± 1 nm. Next, prebaking is performed on the glass substrate on which the resist has been formed in step ST4 at 60 ° C. for 60 minutes. Thereafter, signal information is laser-cut in step ST5. Next, development is performed in step ST6. Then, the resist corresponding to the preformat data pattern is removed. After the development is completed, step ST7
The remaining resist is irradiated with ultraviolet rays (UV) in N ₂ for about 30 seconds. When irradiating with ultraviolet light, as shown in FIG. 2, the glass substrate 2 after development is placed on a stage 1 (400 × 400 mm) which can be moved ± 25 mm in the left-right direction indicated by an arrow X. Then, a UV light is applied to the resist on the glass substrate 2 from a light source 3 provided at a predetermined distance opposite to the glass substrate 2. As the light source 3, seven 100 W low-pressure straight tube mercury lamps having short wavelengths of 185 nm and 254 nm are used.
For example, in this apparatus, the thickness of the glass substrate 2 is set to 10
mm, and when the facing distance between the upper surface of the glass substrate 2 on which the resist is formed and the light source 3 is 15 mm, the light intensity is 7 to 8 mW / cm ² . The irradiation amount of the ultraviolet light at this time is 210 to 240 mJ / cm ^{2 in} irradiation for about 30 seconds.
It becomes. The amount of N ₂ is, for example, about 20 to 50 l / min, and the introduction pressure is about 3 kg / cm ² .
The stage 1 includes cooling water (5
Liters / minute). When the resist is irradiated with ultraviolet rays, the photoresist is polymerized and polymerized. As a result, harder baking conditions can be achieved in post bake 1 in the next step. Next, in order to increase the adhesion between the glass and the resist, at step ST8, the temperature (10
(0 ° C.), that is, baking is performed at 200 ° C. for 3 hours. The baking was carried out at a flow rate of 20 liters of N ₂ /
The glass substrate 2 irradiated with ultraviolet rays is placed in a glass case under an introduction pressure of 3 to 5 kg / cm ² , and baked with the lid closed. As shown in FIG. 3, the temperature is raised to 200 ° C. over about 1 hour, kept at that temperature for 3 hours, and then nitrogen cooled to room temperature over 5 to 6 hours.
Save as is. In FIG. 3, a broken line indicated by A indicates an actual temperature state. By performing such ultraviolet irradiation and baking, the adhesion between the glass and the resist is increased. Next, chemical plating is performed. Since the resist surface is hydrophobic because post-baking is strengthened, about 1N-HCl is used as a chemical plating pretreatment in step ST9. Make the resist surface hydrophilic. Subsequently, a hydrophilic catalyst (Catalyst 9F) is applied, and activated by an accelerator. Then, in step ST10, chemical plating is performed. Chemical plating, when electrolytic plating in the next process,
This is performed to energize the electrodes. Such electroless plating is performed from the side surface of the glass substrate 2 to a part of the back surface, and the resist surface is plated at 1000 °. Next, in step ST11, electroless plating for forming a stamper is performed. In this embodiment, the thickness of the electroless plating is set to 300 μm. Next, at step ST12, the glass substrate 2
In order to remove the stamper by polishing (lapping) the back surface of the substrate, Ni on the end surface of the glass substrate 2 is scraped off. Then, in step ST13, the glass substrate 2
Peel off the stamper. At this time, since the resist is firmly fixed to the glass substrate 2, even if the stamper is peeled off from the glass substrate 2, the resist does not remain on the stamper. That is, the resist remains provided on the glass substrate 2 as it is. Next, the manufactured stamper is inserted into the step S
The resist is washed at T14. The stamper cleaning is performed with acetone. This completes the first stamper. The method for drying the stamper is as follows.
Replace acetone with IPA and shake off and dry at high speed (500 rpm). Then, after checking the thickness of the stamper manufactured in step ST15, a defect check is performed in step ST16 to check for irregularities on the surface of the stamper. Next, in step ST17, a 2P disk is set, and then in step ST18, a signal check is performed to check the signal by actually driving the drive. Next, the stamper is completed by trimming in step ST19. On the other hand, the glass substrate 2 from which the stamper was peeled off
Is reproduced according to the following procedure. In this embodiment,
The glass substrate 2 after laser cutting and development is referred to as a glass master after step ST20. Since the glass master is insoluble in the solvent, the glass master is washed with acetone in step ST21.
PA spin dry. Next, in step ST22, a protective film (clean coat S) is applied to the resist surface. This is to eliminate the influence (stain etc.) due to the salt iron. Next, Ni is removed in step ST23. This is immersed in a ferric chloride solution for about 1 to 2 hours to remove Ni on the edge and the back of the glass master. Then, in step ST24, the protective film is peeled off, and IPA spin-drying is performed again in step ST25 in order to wash the remaining protective film and the like. Next, in step ST26, post bake 2
I do. Here, the glass master is baked again at 200 ° C. for 3 hours. Finally, the chemical plating pretreatment is started in step ST27. Since the glass master has its end face once shaved, silane (about 0.1%) is impregnated with bencot, and the end face and the back face are rubbed by hand. Thereafter, in the step ST where hydrochloric acid is added,
Perform the process of No. 9 and start chemical plating. Further, the steps from the electrolytic plating in step ST11 to the peeling of the stamper in step ST13 are repeated to produce a second stamper. The produced second stamper is obtained by being transferred from the same glass master from which the first stamper is manufactured, and thus has the advantage of having the same characteristics. By repeating the above flow, a plurality of stampers having the same characteristics can be efficiently manufactured. That is, the cost, time (about 3 days), etc., of the process from the precise cleaning in step ST1 to the development in step ST6 can be reduced, and as a result, the cost of the stamper can be reduced. Here, actually, the diameter is set to approximately 64 mm,
A stamper used for manufacturing an optical disk or a magneto-optical disk capable of recording a music signal for approximately 74 minutes was manufactured according to the above-described flow. As a comparative example, similar stampers were manufactured by a conventional method, and the signal characteristics of these stampers in 2P evaluation were examined.
Table 1 shows the results. In Table 1, PP indicates the width of the groove or pit, and RC indicates the height of the groove or pit. [Table 1] As can be seen from the results, by controlling the thickness of the resist and the conditions of laser cutting, signal characteristics equivalent to those of the conventional stamper were obtained.
In addition, the signal characteristics of the first and second sheets of the stamper manufactured by the glass master according to the present invention are almost the same, and it can be seen that the reproducibility is very good. Also,
The groove shape is several steps smoother than that of the conventional product in SEM observation. This is considered a hard baking difference. Although the specific embodiments to which the present invention is applied have been described, the present invention is not limited to the above-described embodiments, and various modifications can be made. For example, the method of the present invention can be applied to the manufacture of a stamper used in manufacturing any optical disk such as a 5.25-inch magneto-optical disk, a 3.5-inch magneto-optical disk, and a write-once optical disk. As is clear from the above description, according to the method of the present invention, the master substrate subjected to the laser cutting and the developing treatment is irradiated with ultraviolet rays and then subjected to the baking treatment. The adhesion between the glass and the resist is increased, so that the resist is prevented from adhering to the stamper when the stamper is peeled off from the master substrate in a subsequent step, and the master substrate can be reused several times. Therefore, a plurality of stampers having the same characteristics can be manufactured from one master substrate, and the quality assurance of the process can be smoothly controlled. According to the method of the present invention, the steps from precision cleaning to development in the stamper manufacturing process can be omitted, and the productivity can be greatly improved. Furthermore, the cost of the stamper, which has been expensive until now, can be significantly reduced by using the present invention.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a flowchart sequentially showing steps of manufacturing a stamper. FIG. 2 is a view showing a step of irradiating a resist with ultraviolet rays in a step of manufacturing a stamper. FIG. 3 is a view showing a processing temperature and a time in a baking processing step after laser cutting, development, and irradiation of ultraviolet rays in a step of manufacturing a stamper. FIG. 4 is a flowchart sequentially showing steps of manufacturing a stamper by a conventional method. [Description of Signs] 1 stage, 2 glass substrate, 3 light source,

Claims (1)

(57) [Claim 1] In a method for manufacturing an optical disk substrate, a glass substrate on which signal information is recorded in advance by laser cutting is used as a master substrate, and an optical disk stamper is manufactured by transfer from the master substrate. In forming the first stamper, the above-mentioned master substrate is subjected to ultraviolet irradiation and baking in an inert atmosphere after laser cutting and development, followed by chemical plating pretreatment, chemical plating and electrolytic plating.
The first stamper is obtained by the steps described above , and thereafter, the master substrate and the first stamper are separated.
After that, the solvent cleaning of the master substrate, the application of the protective film, the Ni plating
When removing the protective film, removing the protective film, washing with a solvent, and baking, and forming the stamper after the second stamper , the chemical plating pretreatment including the addition of acid,
Until plating, peeling of master board and stamper
A method of manufacturing an optical disk substrate, characterized by repeating the steps.