JP3366537B2 - Optical disk, method for manufacturing optical disk, blank master for optical disk, and method for manufacturing blank master for optical disk - Google Patents

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 an optical disc, and more particularly to a method for manufacturing an optical disc for high density recording / reproduction.

[0002]

2. Description of the Related Art Conventionally, there is an optical information disc on which optically readable information is recorded and which is read out by using a laser beam spot. Particularly, in recent years, a compact disc (CD) has been used. ) And CD-ROM
The spread of optical discs, such as that of, is remarkable. As the above CD-ROM, not only for computers but also for multifunctional games, CD-ROMs have recently appeared, and switching from computers to game magnetic disks (floppy disks) and ROM cartridges to CDs is progressing. Further, in recent years, commercialization of a DVD (digital video disk) having a high density of CD has been considered, and it is expected to be used for multimedia other than movies.

As described above, various types of optical discs have appeared, but in manufacturing any optical disc, the process starts with the step of forming a stamper in which pits or grooves of information signals are formed. Then they have in common.

An example of a conventional stamper manufacturing process will be described below with reference to FIG. First, a positive type (or negative type) photoresist 21 is uniformly applied to the surface of a disc-shaped glass substrate 20 that has been precisely polished by an spinner method through an adhesive (not shown), and then a hot plate or the like. To bake. This is called a blank master ((A) in the figure). Next, the laser light 22 modulated by the signal to be recorded is condensed by the lens 23, and this is irradiated onto the photoresist 21 to expose a predetermined portion ((B) in the same figure). The pattern of the exposure unit 24 is a read-only optical disc (CD, LD, CD-ROM, DVD, etc.).
In the case of (1), it is a pit group, and in the case of a recordable / reproducible optical disk (phase change optical disk, magneto-optical disk, write-once optical disk, etc.), it is a groove group. Next, the photoresist 21 is developed by using an alkaline solution such as an aqueous solution of sodium hydrogen phosphate to dissolve the exposed portion 24 to obtain a concavo-convex pattern of the photoresist 21 composed of pit groups or groove groups (see FIG. 7C). ).

Next, a conductive film (not shown) of nickel or the like is formed on the photoresist 21 by a sputtering method or the like.
Is formed, and nickel 25 is formed by using this conductive film as an electrode.
Is plated to a predetermined thickness ((D) in the figure). As a result, the reverse pattern of the concavo-convex pattern of the photoresist 21 is copied onto the nickel 25. Next, this nickel 2
The stamper is completed by peeling 5 from the glass substrate 20 and removing the resist 21 ((E) in the figure). After that, injection molding is performed using this stamper to form a reflection film (recording film), a protective film, and the like, whereby an optical disk is manufactured. The optical disc is subjected to pasting, printing, etc., if necessary.

By the way, one of the indexes for measuring the performance of the signal recorded on the optical disk is the jitter of the reproduced signal. The jitter value represents the degree of dispersion of the reproduced signal, and the smaller the value, the higher the quality of the optical disc. That is, if the optical disc has a small jitter value, it has a margin against the warp of the disc caused by the inclination of the disc and the change in temperature and humidity when used in the drive, and stable reproduction can be performed. On the other hand, in the case of an optical disc with a large jitter value, when the jitter value further increases due to changes in the usage environment,
It becomes difficult to separate pits (separation of reproduced signals) by the pickup, C1 errors increase in some cases, and in the worst case, signal reproduction itself of the optical disc becomes impossible. In the DVD, the jitter (a value obtained by normalizing the fluctuation of the signal after waveform equalization in the time axis direction by the channel bit clock) is required to be 8% or less.

[0007]

However, there is a problem that the jitter value of the reproduction signal of the optical disk becomes a large value depending on the stamper used at the time of manufacturing. That is, a stamper with a large jitter value and a stamper with a small jitter value are mixed. This is not desirable in terms of quality control, and the fact that a disc with a large jitter value is distributed in the market leads to consumers who can or cannot play the disc depending on the usage environment.

On the other hand, at the manufacturing site, there is a problem that the resist film may flow in the post-exposure development with a small probability. If even a small amount of pits flow, signals will be lost in that part, resulting in a defective product. As described above, in the manufacture of the optical disc, there are two problems of instability of jitter and instability of development, and it is necessary to take measures against these problems.

[0009]

As a means for achieving the above object, it is an object of the present invention to provide a manufacturing method for manufacturing a blank master in which the interval between the glass plate polishing step and the resist coating step is within 24 hours. . First of the present invention
Of the invention is a method for producing a blank master for an optical disc, in which at least a glass disc polishing step, a cleaning step, a drying step, an adhesive coating step, a resist coating step and a baking step are performed in this order, and the adhesive agent In the coating process
The welding agent used is hexamethyldisilazane,
The resist used in the resist coating step is ethyl lactate, propylene glycol monomethyl ether acetate, butyl acetate, ethyl pyruvate, methyl-3-methoxypropionate, methyl-3-ethoxypropionate, methylamylketone, cyclohexanone and has been diluted in at least any one solvent of ethyl cellosolve acetate, so as to perform the resist coating process from the glass plate of the polishing process is completed within 24 hours, the within 24 hours , The polisher
Between the end of the process and the cleaning process,
A first storage time for storing the glass master after the end,
From the end of the drying process to the step of applying the adhesive
Store the glass master after the drying process in between.
A method for manufacturing a blank master for an optical disc is provided, which is a time obtained by adding two storage times . A second invention provides an optical disc blank master manufactured by the method for manufacturing an optical disc blank master according to claim 1. According to a third aspect of the present invention, after the resist of the blank master for an optical disk according to claim 2 is irradiated with light to form a latent image, development is performed to produce a stamper on which an information signal is formed, and the stamper is used. Provided is a method for manufacturing an optical disk, which comprises manufacturing an optical disk. A fourth invention provides an optical disc manufactured by the optical disc manufacturing method according to the third aspect.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION There are two problems in the conventional manufacturing method, but the inventors of the present invention have made earnest studies, and as a result, the present invention has been made to solve these problems. That is, when the manufacturing records were examined for the two causes of instability, the cause was the quality of the blank master, and these problems occurred when the time interval between the polishing process day and the resist coating process day was large. I knew that. Then, it was found that when the polishing day and the coating day were the same day, the least jitter was stably obtained and no development flow occurred.

The reason for this seems to be that the adhesion between the glass plate and the resist plate is involved. That is, the glass immediately after polishing is the most active and shows the strongest adhesion to the resist. It is considered that after polishing, the surface activity decreases with time and the adhesive force of the resist also decreases. Therefore, the latent image of uniform pits formed by exposure causes uneven image formation on a board with weak adhesion when forming a shape by development, and when the adhesion is extremely small, the resist film develops. It will flow with liquid. In the case of non-uniform image formation, this is observed as a fluctuation of the reproduction signal, and the jitter value fluctuates significantly.
Therefore, it is desirable to apply the resist immediately after polishing, but the fluctuation of the jitter value can be reduced by setting the interval between the polishing step of the glass plate and the resist applying step within approximately 24 hours.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the method for manufacturing a blank master for an optical disk of the present invention will be described below with reference to FIG. Figure 1
(A)-(I) is process drawing for demonstrating one Example of the manufacturing method of the blank master for optical disks of this invention. The results of Examples 1 to 9 and Comparative Examples 1 to 7 are shown in Table 1.
Shown in.

<Example 1> Method for manufacturing a disk: FIGS. 1A to 1I. First, a disk-shaped glass substrate is precisely polished with cerium oxide (A). Then, it was temporarily stored in isopropyl alcohol ((B), storage time t1 = 0.1 hour). Then, the substrate is cleaned by brush cleaning and ultrasonic cleaning in ultrapure water (C). Furthermore, the washing process was completed by spin drying (D). This was temporarily stored in clean air ((E), storage time t2 = 0.1 hour). And
The adhesive agent was left in saturated vapor of hexamethyldisilazane (HMDS) for 3 minutes to apply the adhesive agent (F). Then, the photoresist TSMR-V3 (Tokyo Ohka Kogyo Co., Ltd.) was diluted with ethyl cellosolve acetate (ECA), and applied with a spinner to a film thickness of 70 nm (G). Finally, bake this at 80 ° C (H)
A blank master (see FIG. 2 (A)) was completed (I).

The blank master is laser-emitted.
The FM signal was used to form a latent image with a shortest pit length of 0.254 μm and a track pitch of 0.6 μm (see FIG. 2B). After that, development was performed with a 0.2 N sodium hydrogen phosphate aqueous solution to form pits of information signals (see FIG. 2C).
After that, the stamper was created by the usual method. Then, in the same manner, 30 stampers were prepared, and one reproduction-only optical disk was prepared for each of these stampers. The thickness of the injection-molded substrate was 0.6 mm, and the total thickness was 1.2 mm by adopting a two-sheet bonding structure. However, the substrate to be bonded is an optical disc in which pits for information signals are formed on only one surface and the other substrate surface has no mirror surface signal.

Evaluation method 1: Jitter evaluation is carried out by using a laser wavelength of 4 for each optical disk produced by the above method.
The signal after passing through the equalizer was measured by a drive device having an optical head of 13 nm (Kr) and a lens NA of 0.6, and the average value was obtained.

Evaluation method 2: Stripping of the resist film at the time of development was visually detected, and it was judged by an optical microscope whether or not it was stripped. Table 1 shows the number of stripped optical disks among the 30 sheets.

As a result of Evaluations 1 and 2, the average jitter value of the optical discs obtained from 30 stampers was 6.0%. Further, no development peeling occurred.

[0018]

[Table 1]

<Examples 2 to 6> [storage time t1, storage time t2] are [4, 2], [20, 0.1],
[0.1, 20], [24, 0.1], [0.1, 2
4] (time) and otherwise the same as in Example 1, 30 stampers were prepared, and one reproduction-only optical disc was prepared using each of these stampers.
Then, the evaluations according to Evaluation Method 1 and Evaluation Method 2 were performed. It can be seen that the average jitter value of the optical disk is at most 7.4%, and the shorter the total time of the storage times t1 and t2, the better the value. Then, no development peeling occurred.

<Example 7> 30 stampers were prepared in the same manner as in Example 1 except that isopropyl alcohol was not stored (storage time t1 = 0), and the washing step was performed. One reproduction-only optical disc was prepared for each. The storage time t2 =
It is 0.1. Then, the evaluations according to Evaluation Method 1 and Evaluation Method 2 were performed. In the case of the storage time t1 = 0, if the storage time t2 = 0.1, the time interval from the glass plate polishing step to the resist coating step is the shortest in the examples, and the average jitter value is 6.0%. It was the smallest value. Further, neither development peeling nor single sheet occurred.

<Examples 8 and 9> Thirty stampers were prepared in the same manner as in Example 1 except that the solvent for diluting the resist was replaced with ethyl lactate (EL) and propylene glycol monomethyl ether acetate (PGMEA). A reproduction-only optical disc was prepared for each of these stampers. Then, the evaluations according to Evaluation Method 1 and Evaluation Method 2 were performed. Even when the solvent for diluting the resist was replaced with ethyl lactate or propylene glycol monomethyl ether acetate, the evaluation results did not change, the average jitter values of the optical disc were 6.2% and 6.0%, and no development peeling occurred.

<Comparative Examples 1 to 7> [storage time t1, storage time t2] are [28, 0.1] and [0.1, 2], respectively.
8], [42, 0.1], [0.1, 42], [80,
0.1], [168,0.1], [360,0.1]
(Hours), and otherwise the same as in Example 1, and 3
0 stampers were produced, and one read-only optical disc was produced by each of these stampers. Then, the evaluations according to Evaluation Method 1 and Evaluation Method 2 were performed. The average jitter value of the optical disk is 7.1 when the total time of the storage times t1 and t2 is 28.1 hours and when the time t2 is 0.1 hour.
Although the value of 6% is obtained, it is not necessarily good because t2 is 8.0% at 28 hours. The longer the total storage time t1 and t2, the worse the jitter value. Further, when the total time of the storage times t1 and t2 exceeds 80 hours, development peeling occurred and it was judged that the development was defective.

As described above in each embodiment, the optical disc manufactured according to the present invention always has a jitter of 8.0%.
It is as small as less than 1 and there is no peeling of development. Further, the present invention is not limited to the above-mentioned embodiments. For example,
As for the resist solvent, ethyl pyruvate, methyl-3-, as well as ethyl cellosolve acetate and ethyl lactate, and propylene glycol monomethyl ether acetate are used.
Methoxypropionate, methyl-3-ethoxypropionate, butyl acetate, methyl amyl ketone, cyclohexanone, etc. may be used. Furthermore, Example 1 shown in FIG.
In FIG. 7B, the storage shown in FIG. The cleaning shown in FIG. 6 (C) may be a detergent cleaning, the drying shown in FIG. 5 (D) may be hot water pull-up drying, or another coupling agent may be used instead of HMDS shown in FIG. Alternatively, spin coating may be performed instead of the above coating. Moreover, you may dry and bake after application. And, in each of the above-mentioned examples, the bonded single-layer disc was taken up, but a double-sided disc,
The present invention can be applied to a multi-layer disc or the like.
Further, it goes without saying that the recording / playback type disc, the partial ROM disc, a combination thereof and the like are also effective.

[0024]

The optical disk manufacturing method of the present invention has the effect of providing an optical disk with a small jitter value and a stamper with no development flow.

[Brief description of drawings]

FIG. 1 is a process chart for explaining an embodiment of a method for manufacturing a blank master for an optical disc of the present invention.

FIG. 2 is a process drawing for explaining a stamper manufacturing process.

[Explanation of symbols]

20 disk-shaped glass substrate 21 Positive photoresist 22 Laser light 23 lenses 24 Exposure section 25 Nickel (Stamper)

Continued front page       (56) References JP-A-8-273217 (JP, A)                 Japanese Unexamined Patent Publication No. 8-273216 (JP, A)                 JP-A-8-273215 (JP, A)                 JP-A-6-28720 (JP, A)                 JP-A-55-67742 (JP, A)                 JP-A-7-235084 (JP, A)

Claims (4)

(57) [Claims] 1. A method of manufacturing a blank master for an optical disc, wherein at least a polishing step, a cleaning step, a drying step, an adhesive applying step, a resist applying step and a baking step of a glass plate are performed in this order. The welding agent used in the agent application process is hexamethy
The resist used in the resist coating step is rudysilazane, and is ethyl lactate, propylene glycol monomethyl ether acetate, butyl acetate, ethyl pyruvate, methyl-3-methoxypropionate, methyl-3-ethoxypropionate, methylamyl. One diluted with at least one of the solvents of ketone, cyclohexanone, and ethyl cellosolve acetate, and the resist coating step is performed within 24 hours after the polishing step of the glass plate is completed. And before
Within 24 hours, after the polishing process is completed, the cleaning process is performed.
During the process, the glass raw material after the polishing process is completed.
The first storage time to store the board, and after the drying process
After completion of the drying process before the adhesion agent coating process
And the second storage time for storing the glass master disk
A method for manufacturing a blank master for an optical disk, which is characterized by time . 2. A blank master for an optical disk, which is manufactured by the method for manufacturing a blank master for an optical disk according to claim 1. 3. A blank master for an optical disk according to claim 2 is irradiated with light to form a latent image and then developed to prepare a stamper having an information signal formed thereon, and the stamper is used to form an optical disk. A method for manufacturing an optical disc, comprising: 4. An optical disc manufactured by the optical disc manufacturing method according to claim 3.