JPH0762916B2 - Read-only optical disc - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to an optical disc for reading information using a laser, and more particularly to a read-only optical disc excellent in reliability and weather resistance.

(Prior Art) A compact disc (hereinafter referred to as a CD) is widely known as a read-only optical disc. The CD has a structure in which a reflection film made of aluminum and a protective film made of a UV curable resin are provided on a polycarbonate substrate (hereinafter, referred to as a PC substrate), and minute unevenness (hereinafter, referred to as a fine irregularity) formed on the PC substrate in advance. , Pits) is used to enable sound reproduction.

In recent years, the CD-ROM has been used not only for the audio reproduction described above.
Read-only optical disks for various types of data called "data" are also being used in various fields. For example, it is being applied to data media for personal computers and electronic publishing media.

(Problems to be solved by the invention) Although a CD-ROM can be easily manufactured using a conventional CD manufacturing technique using a PC substrate, it is strongly required to have reliability of reading and data storability (weather resistance of CD-ROM). If so, it will be a problem with the PC board. That is, due to the water absorption and moisture permeability of the PC substrate, warpage or deterioration of the reflective film such as corrosion and peeling is likely to occur. Further, even in the case of a CD, for example, when it is installed in a vehicle, the environmental conditions are severe, and higher quality is required.

An object of the present invention is to provide a read-only optical disc having high reliability and high weather resistance.

(Means for Solving the Problems) The present invention will be described below with reference to FIG. FIG. 1 is a schematic sectional view of the present invention.

According to the present invention, a glass substrate having neither hygroscopicity nor moisture permeability is used, and first, the diffusion prevention layers 2a and 2b are formed on both surfaces. next,
A baking layer 3 of metal alcoholate having a glass-like pit pattern obtained by baking an organometallic compound is formed on one surface of the diffusion preventing layer by using a so-called sol-gel method. A highly reliable read-only optical disc can be obtained by sequentially stacking the anticorrosion reflective film 4 and the protective film 5.

Usual soda lime glass, aluminosilicate glass, or the like is used as the glass substrate 1, but from the viewpoint of reliability as an optical disc, a chemically strengthened one is preferable.

However, in order to carry out normal chemical strengthening, the glass
It is necessary to contain alkali metals such as Li and Na. This alkali metal, when the glass is placed under high temperature and high humidity,
It is well known that it diffuses on the glass surface and changes into a salt such as Na ₂ CO ₃ . Such a change becomes an obstacle when performing reading by irradiating a laser beam and is not preferable in terms of characteristics as an optical disc. Therefore, diffusion prevention layers 2a and 2b that prevent such salt precipitation are required. Various inorganic oxides can be used as the diffusion prevention layers 2a and 2b, but considering the characteristics of the optical disk, Si, Ti, Ta, Z
It is preferable to use r, Al, Sn, and Cr oxides alone or in combination. In addition, Si ₃ N ₄ also shows good results.
These oxides or nitrides can be easily formed by a sputtering method or the like.

A desired pit pattern can be easily formed on the diffusion preventing layer by using a sol-gel method as shown below.

First, a coating solution containing a metal alcoholate, water, hydrochloric acid, alcohol, etc. is prepared and spin-coated on a glass substrate so as to have a predetermined thickness. Then, press a resin mold designed to have the desired pit pattern,
Primary firing is performed at a temperature of about 60 to 120 ° C. After that, the glass substrate is released from the mold, the secondary baking is performed at 250 to 400 ° C., the solvent,
By removing organic components such as additives, the amorphous metal oxide layer 3 having a desired pit pattern can be formed.

As the metal alcoholate used here, various metal alcoholates, for example, alcoholates such as Si, Ti, Zr, Al, and B can be used. Alcoholate or
A mixed system of Si-based alcoholate and Ti-based alcoholate is preferable.

In this way, a transparent glass substrate having a desired pit pattern can be obtained.

Next, on the fired layer having the obtained pit pattern,
The reflective film 4 is attached by a sputtering method, and the protective film 5 is further added.
A read-only optical disc is obtained by coating the above with.

As the material of the reflective film 4, various metals, metal nitrides, etc. can be used, but those showing high corrosion resistance are preferable, and Au, Au-based alloys and TiN satisfy the object of the present invention.

As the protective film 5, an inorganic oxide such as SiO ₂ or an inorganic nitride such as Si ₃ N ₄ or an organic one such as a UV curable resin can be used alone or in combination.

(Operation) Since the read-only optical disc according to the present invention has the glass substrate with the diffusion prevention layer having excellent moisture resistance and the reflective film having excellent corrosion resistance, high reliability can be realized.

(Example) Hereinafter, it demonstrates in detail based on an Example.

Example 1 On a chemically strengthened glass substrate, a SiO ₂ film of 1000 liters was formed on both surfaces of the glass substrate by a sputtering method to form a diffusion prevention layer. Next, an ethyl alcohol solution containing tetraethoxysilane, hydrochloric acid, water, and polyethylene glycol was spin-coated on one of the SiO ₂ films, and an organometallic compound was added to 2000
~ 3000Å formed. Then, a resin mold having a predetermined pit pattern on the surface is pressed against the organometallic compound layer,
The pit pattern was transferred and primary firing was performed at 120 ° C. After that, the glass substrate was released, and secondary firing was performed at 350 ° C.

On the fired layer having a pit pattern produced in this way, an Au-Ta alloy film was formed as a reflective film by a sputtering method in an amount of about 10 μm.
00Å and 1000Å SiO ₂ film was sequentially formed as a protective film.

When the weather resistance of the obtained optical disk was evaluated at 80 ° C. and 90% RH, the block error rate, which had an initial value of 1.8 × 10 ⁻³ , slightly increased to 2.1 × 10 ⁻³ after 500 hours. However, such a change does not cause any problem in reproduction characteristics. Also, under the conditions of 80 ℃ and 90% RH, 1
After leaving it for about an hour, taking it out and playing it,
I was able to reproduce without any abnormalities.

Example 2 Si was sputtered on both sides of a chemically strengthened glass substrate.
An O ₂ —Ta ₂ O ₅ film was formed at 1000 Å. Then one of the SiO ₂ -T
An ethyl alcohol solution containing tetraethoxysilane, hydrochloric acid, water, and polyethylene glycol was spin-coated on the a ₂ O ₅ film to form an organometallic compound layer at 2000 to 3000 Å. Next, a resin mold having a predetermined pit pattern on the surface was pressed against the organometallic compound layer to transfer the pit pattern and perform primary baking at 120 ° C. After that, the glass substrate was released, and secondary firing was performed at 350 ° C.

An Au-Ta alloy film of about 1000 Å and an SiO ₂ film of 1000 Å were sequentially formed on the fired layer having a pit pattern thus produced by a sputtering method.

The resulting 80 ° C. The optical disc was evaluated for weather resistance under 90% RH, the block error rate that the initial value was 2.2 × 10 ^-3 it is after 500 hours showed a slight increase in the 2.4 × 10 ^-3. However, such a change does not cause any problem in reproduction characteristics. Also, after leaving it for about 1 hour under the conditions of 80 ° C. and 90% RH, and taking it out and regenerating it, it could be regenerated without any abnormality.

Example 3 Both sides of a chemically strengthened glass substrate were sputtered.
A SiO ₂ —TiO ₂ film of 1000 Å was formed. Next, as in Example 2, a firing layer, a reflective film, and a protective film were sequentially formed.

When the weather resistance of the obtained optical disk was evaluated at 80 ° C. and 90% RH, the block error rate, which had an initial value of 1.3 × 10 ⁻³ , slightly increased to 1.9 × 10 ⁻³ after 500 hours. However, such a change does not cause any problem in reproduction characteristics. Also, under the conditions of 80 ℃ and 90% RH, 1
After leaving it for about an hour, taking it out and playing it,
I was able to reproduce without any abnormalities.

Example 4 Both sides of a chemically strengthened glass substrate were sputtered.
A SiO ₂ —ZrO ₂ film was formed at 800 Å. Next, as in Example 2, a firing layer, a reflective film layer, and a protective film layer were sequentially formed.

When the weather resistance of the obtained optical disk was evaluated at 80 ° C. and 90% RH, the block error rate, which had an initial value of 3.1 × 10 ⁻³ , slightly increased to 3.9 × 10 ⁻³ after 500 hours. However, such a change does not cause any problem in reproduction characteristics. Also, under the conditions of 80 ℃ and 90% RH, 1
After leaving it for about an hour, taking it out and playing it,
I was able to reproduce without any abnormalities.

Example 5 Both sides of a chemically strengthened glass substrate were sputtered.
A SiO ₂ —CrO ₂ film was formed at 800 Å. Next, as in Example 2, a firing layer, a reflective film layer, and a protective film layer were sequentially formed.

When the weather resistance of the obtained optical disk was evaluated at 80 ° C. and 90% RH, the block error rate, which had an initial value of 2.3 × 10 ⁻³ , slightly increased to 2.9 × 10 ⁻³ after 500 hours. However, such a change does not cause any problem in reproduction characteristics. Also, under the conditions of 80 ℃ and 90% RH, 1
After leaving it for about an hour, taking it out and playing it,
I was able to reproduce without any abnormalities.

Example 6 Both sides of a chemically strengthened glass substrate were sputtered.
A SiO ₂ —Al ₂ O ₃ film was formed at 800 Å. Next, as in Example 2, a firing layer, a reflective film, and a protective film were sequentially formed.

When the weather resistance of the obtained optical disk was evaluated at 80 ° C. and 90% RH, the block error rate, which had an initial value of 2.6 × 10 ⁻³ , slightly increased to 3.1 × 10 ⁻³ after 500 hours. However, such a change does not cause any problem in reproduction characteristics. Also, under the conditions of 80 ℃ and 90% RH, 1
After leaving it for about an hour, taking it out and playing it,
I was able to reproduce without any abnormalities.

Example 7 Both sides of a chemically strengthened glass substrate were sputtered.
A SiO ₂ —SnO ₂ film of 1000 Å was formed. Next, as in Example 2, a firing layer, a reflective film, and a protective film were sequentially formed.

When the weather resistance of the obtained optical disk was evaluated at 80 ° C. and 90% RH, the block error rate, which had an initial value of 2.2 × 10 ⁻³ , slightly increased to 2.6 × 10 ⁻³ after 500 hours. However, such a change does not cause any problem in reproduction characteristics. Also, under the conditions of 80 ℃ and 90% RH, 1
After leaving it for about an hour, taking it out and playing it,
I was able to reproduce without any abnormalities.

Example 8 Both sides of a chemically strengthened glass substrate were sputtered.
An SiO ₂ —Ta ₂ O ₅ film of 1000 Å was formed. Then one of the SiO ₂
An ethyl alcohol solution containing tetraethoxysilane, tetrabutoxytitanium, hydrochloric acid, water, and polyethylene glycol was spin-coated on the Ta ₂ O ₅ film to form an organometallic compound layer of 2000 to 3000 liters. Then, a resin mold having a predetermined pit pattern on the surface was pressed against the organometallic compound layer to transfer the pit pattern and perform primary baking at 100 ° C. After that, the glass substrate was released, and secondary firing was performed at 350 ° C.

On the fired layer having the pit pattern produced in this manner, an Au-Ge alloy film was formed as a reflective film by a sputtering method to about 10
00Å and 1000Å SiO ₂ films were sequentially formed. Furthermore, it was covered with a UV curable resin layer.

When the weather resistance of the obtained optical disk was evaluated at 80 ° C. and 90% RH, the block error rate, which had an initial value of 1.5 × 10 ⁻³ , slightly increased to 2.0 × 10 ⁻³ after 500 hours. However, such a change does not cause any problem in reproduction characteristics. Also, under the conditions of 80 ℃ and 90% RH, 1
After leaving it for about an hour, taking it out and playing it,
I was able to reproduce without any abnormalities.

Example 9 A Si ₃ N ₄ film having a thickness of 800 Å was formed on the both sides of a chemically strengthened glass substrate by a sputtering method. Then one of
An ethyl alcohol solution containing tetraethoxysilane, tetrabutoxytitanium, hydrochloric acid, water and polyethylene glycol was spin-coated on the Si ₃ N ₄ film to form an organometallic compound layer of 2000 to 3000 liters. Then, a resin mold having a predetermined pit pattern on the surface was pressed against the organometallic compound layer to transfer the pit pattern and perform primary baking at 100 ° C. After that, the glass substrate was released, and secondary firing was performed at 350 ° C.

On the fired layer having a pit pattern thus produced, an Au—Ge alloy film of about 1000 Å and a SiO ₂ film of 1000 Å were sequentially formed by a sputtering method. Furthermore, it was covered with a UV curable resin layer.

The resulting 80 ° C. The optical disc was evaluated for weather resistance under 90% RH, the block error rate that the initial value was 1.4 × 10 ^-3 it is after 500 hours showed a slight increase in the 1.6 × 10 ^-3. However, such a change does not cause any problem in reproduction characteristics. Also, after leaving it for about 1 hour under the conditions of 80 ° C. and 90% RH, and taking it out and regenerating it, it could be regenerated without any abnormality.

Example 10 A TiN film of about 1 was formed by a cluster ion beam method on a firing layer having a pit pattern produced in the same manner as in Example 2.
000Å, Si ₃ N ₄ film was sequentially formed by 800 to 10000Å by the sputtering method. Furthermore, it was covered with a UV curable resin layer.

When the weather resistance of the obtained optical disk was evaluated at 80 ° C. and 90% RH, the block error rate, which was an initial value of 2.0 × 10 ⁻³ , slightly increased to 2.5 × 10 ⁻³ after 500 hours. However, such a change does not cause any problem in reproduction characteristics. Also, under the conditions of 80 ℃ and 90% RH, 1
After leaving it for about an hour, taking it out and playing it,
I was able to reproduce without any abnormalities.

Example 11 On the pit pattern layer produced in the same manner as in Example 2, an Au film of about 1000 Å and a Si ₃ N ₄ film of 800 were formed by the sputtering method.
~ 1000Å The film was formed sequentially. Furthermore, it was covered with a UV curable resin layer.

When the weather resistance of the obtained optical disk was evaluated at 80 ° C. and 90% RH, the block error rate, which had an initial value of 2.4 × 10 ⁻³ , slightly increased to 3.3 × 10 ⁻³ after 500 hours. However, such a change does not cause any problem in reproduction characteristics. Also, under the conditions of 80 ℃ and 90% RH, 1
After leaving it for about an hour, taking it out and playing it,
I was able to reproduce without any abnormalities.

Comparative Example When the weather resistance of a commercially available music CD disk was evaluated in the same manner, the block error rate was 5 ×.
It changed significantly from 10 ^-4 (initial value), and it became impossible to measure after 500 hours. Also, after leaving it under conditions of 80 C and 90% RH for about 1 hour, it was taken out and regenerated, and it was impossible to regenerate because of a large warp.

(Effects of the Invention) As described above, the read-only optical disk according to the present invention is excellent in reliability and weather resistance, and can be applied to an application field that cannot be used conventionally.

[Brief description of drawings]

FIG. 1 is a schematic sectional view of a read-only optical disc according to the present invention. 1 ... glass substrate, 2a, 2b ... diffusion prevention layer, 3 ... metal alcoholate firing layer, 4 ... reflection film layer, 5 ... protective film layer

Front Page Continuation (72) Inventor Mikiko Saito 5-33-1 Shiba, Minato-ku, Tokyo NEC Corporation Stock company (72) Yuji Tsukamoto 5-33-1 Shiba, Minato-ku, Tokyo NEC Corporation In-house (72) Inventor Akinobu Sato 5-33-1 Shiba, Minato-ku, Tokyo NEC Corporation In-house (72) Inventor Yoshihiro Matsuno 3-5-11 Doshomachi, Chuo-ku, Osaka-shi, Osaka Nippon Sheet Glass Incorporated (72) Inventor Toshio Kaku 3-5-11 Doshumachi, Chuo-ku, Osaka-shi, Osaka Inside Nippon Sheet Glass Co., Ltd. (72) In-house Shinya Katayama 3-5-11 Dosho-cho, Chuo-ku, Osaka Within Nippon Sheet Glass Co., Ltd. (72) Inventor Atsunori Matsuda 3-5-11 Doshomachi, Chuo-ku, Osaka City, Osaka Prefecture Within Nippon Sheet Glass Co., Ltd. (56) Reference JP-A-3-30132 (JP, A) Flat 3-30133 (JP, A) JP 3-40243 (JP, A)

Claims (3)

[Claims] 1. A diffusion preventive layer is formed on both sides of a transparent glass substrate, and one of the diffusion preventive layers is a metal alcoholate calcined layer having fine irregularities, A.
A read-only optical disk comprising a reflective film and a protective film, which are made of u, Au alloy or TiN, sequentially laminated. 2. The diffusion preventing layer is an oxide composed of at least one element selected from Si, Ti, Ta, Al, Zr, Sn and Cr. The read-only optical disc according to item 1. 3. The read-only optical disk according to claim 1, wherein the diffusion prevention layer is Si ₃ N ₄ .